WO2021168551A1 - Method of coating a carbon surface - Google Patents

Method of coating a carbon surface Download PDF

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Publication number
WO2021168551A1
WO2021168551A1 PCT/CA2021/050208 CA2021050208W WO2021168551A1 WO 2021168551 A1 WO2021168551 A1 WO 2021168551A1 CA 2021050208 W CA2021050208 W CA 2021050208W WO 2021168551 A1 WO2021168551 A1 WO 2021168551A1
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WO
WIPO (PCT)
Prior art keywords
coating composition
sec
external surface
aqueous
kpa
Prior art date
Application number
PCT/CA2021/050208
Other languages
French (fr)
Inventor
Maria V. TORREALBA
Ghislain GONTHIER
Claude Allaire
Lobna JERBI
Original Assignee
Laboratoire Cir Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Laboratoire Cir Inc. filed Critical Laboratoire Cir Inc.
Publication of WO2021168551A1 publication Critical patent/WO2021168551A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/89—Coating or impregnation for obtaining at least two superposed coatings having different compositions
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/44—Carbon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
    • C25C3/12—Anodes
    • C25C3/125—Anodes based on carbon
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0087—Uses not provided for elsewhere in C04B2111/00 for metallurgical applications
    • C04B2111/00879—Non-ferrous metallurgy

Definitions

  • the subject matter disclosed generally relates to methods of coating a carbon material, and more particularly to methods of coating a carbon material with an aqueous priming coating composition for covering surfaces of said carbon materials to form a first layer thereon.
  • Coating a substrate can be thought of as a simple and common task. Beyond all the variables to be considered in the coating process, standard procedures and methods have been developed over the years according to many different applications required in the market. However, when developing a new product or process, each variable must be taken into account to select the best method, perform it in the most effective way and accomplish the desired duty.
  • carbon anode surfaces possess what could be termed a partial wetting surface that requires the application of a large amount of energy from a liquid to break the high energy that is intrinsic to the surface.
  • the coating when the coating is applied to the anode substrate, it shows a typical behaviour of a liquid with high cohesion force, which results in the coating intending to keep its droplet shape instead of spreading easily onto and into the surface; so it may be said that the carbon anode surface energy is weaker than the surface tension of the coating.
  • the interaction between the carbon anode and the coating is not strong enough to reach the necessary level of interfacial tension between the carbon anode and the coating, which leads to a poor wettability from the anode surface and therefore creates a challenge when applying the coating directly to the carbon surface.
  • a method of coating a carbon material with an aqueous priming coating composition for covering an external surface exposed to air of said carbon material, to form a first layer thereon the aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water; the method comprising the step of applying to said external surface a stream of said aqueous priming coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa, from a first distance from said external surface of about 8 cm to about 30 cm, perpendicular to said external surface, and simultaneously applying a curtain of air at a velocity of about 35 m/s to about 55 m/s, from a second distance from said external surface of about 10 mm to about 40 mm perpendicular to said external surface
  • the carbon material may be a carbon anode.
  • the carbon anode may be a prebaked consumable carbon anode.
  • the layer of said aqueous priming coating composition on said external surface may have a wet film thickness of about 0.100 mm to about 0.50 mm.
  • the layer of said aqueous priming coating composition on said external surface may have a wet film thickness of about 0.100 mm to about 0.150 mm.
  • the stream of said aqueous priming coating composition may comprise an application pattern of from about 8 cm to about 40 cm.
  • the application pattern may be from about 20 cm to about 35 cm.
  • Applying said stream of said aqueous priming coating composition may be at a flow rate of about 0.4 L/min to about 1 L/min.
  • the flow rate may be of about 0.55 L/min.
  • the velocity may be from about 45 m/s to about 50 m/s.
  • the velocity may be about
  • the stream of said aqueous priming coating composition and said curtain of air may be displaced perpendicular to said external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec.
  • the displacement velocity may be from about 4 to about 17 cm/sec.
  • the aqueous priming coating composition may be dried at room temperature for about 2 minutes or more, prior to application of a subsequent aqueous priming coating composition layer.
  • said external surface may have a surface temperature of about 5°C to about 50°C.
  • the aqueous priming coating composition may be applied at a temperature of about
  • the aqueous priming coating composition may be streamed through gas at about 275 kPa.
  • the first distance from said external surface may be of about 15 cm to about 20 cm.
  • the first distance from said external surface may be of about 10 cm.
  • the second distance from said external surface may be of about 13 mm to about 30 mm.
  • the distance between a central axis of said stream of said aqueous priming coating composition and a central axis of said curtain of air may be from about 100 mm to about 300 mm.
  • the distance may be from about 125 mm to about 200 mm.
  • the method may further comprise applying an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
  • an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
  • the aqueous coating composition may form a layer having a wet film thickness of about 0.15 mm to about 0.50 mm.
  • the aqueous coating composition may form a layer having a wet film thickness of about 0.25 ⁇ 0.05 mm.
  • said dry layer may have a surface temperature of about 74°C to about 100°C.
  • the aqueous coating composition may be applied at a temperature of about 48°C to about 52°C.
  • the second or more layer of said aqueous priming coating composition may be applied by the method of claim 1 , by spray coating, or a combination thereof.
  • a system for coating a carbon material with a fluid coating composition for covering an external surface exposed to air of said carbon material comprising: a) a spray gun, configured to apply to said external surface a stream of fluid coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa, said spray gun positioned at a first distance from said external surface of about 8 cm to about 30 cm, perpendicular to said external surface, b) an apparatus for producing an air curtain, configured to apply a curtain of air at a velocity of about 35 m/s to about 55 m/s, from a second distance from said external surface of about 10 mm to about 40 mm perpendicular to said external surface, wherein said system may be configured for application of said fluid coating composition as a stream under pressure simultaneously with said air curtain, to provide an even distribution of said fluid coating composition.
  • the system may further comprise a fluid coating composition reservoir, in fluid communication with said spray gun.
  • the fluid coating composition reservoir may be a high-pressure reservoir.
  • the fluid coating composition reservoir may further comprise an agitator.
  • the system may further comprise a compressor in fluid communication with said apparatus for producing an air curtain, to provide compressed air thereto.
  • the system may further comprise an air dehumidifier.
  • the spray gun may provide an application pattern of from about 8 cm to about 40 cm.
  • the application pattern may be from about 20 cm to about 35 cm.
  • the velocity may be from about 45 m/s to about 50 m/s.
  • the velocity may be about
  • the spray gun and said apparatus for producing an air curtain may be displaced perpendicular to said external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec.
  • the displacement velocity may be from about 4 cm/sec to about 17 cm/sec.
  • the spray gun may be configured to stream through gas at about 275 kPa.
  • the first distance from said external surface may be of about 15 cm to about 20 cm.
  • the first distance from said external surface may be of about 10 cm.
  • the second distance from said external surface may be of about 13 mm to about 30 mm.
  • the distance between a central axis of said spray gun and a central axis of said apparatus for producing an air curtain may be from about 100 mm to about 300 mm.
  • the distance may be from about 125 mm to about 200 mm.
  • the fluid coating composition may be an aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water.
  • AI2O3 aluminum oxide
  • the fluid coating composition may be an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of said aqueous priming coating composition.
  • solution is intended to mean a homogeneous mixture composed of two or more substances.
  • aqueous solution is when one of the solvents is water.
  • a solute is a substance dissolved in another substance, known as a solvent.
  • the mixing process of a solution happens at a scale where the effects of chemical polarity are involved, resulting in interactions that are specific to solvation.
  • the solution assumes the phase of the solvent when the solvent is the larger fraction of the mixture, as is commonly the case.
  • concentration of a solute in a solution is the mass of that solute expressed as a percentage of the mass of the whole solution.
  • carbon material is intended to mean an object or item that is made from carbon (i.e., graphite, petroleum or metallurgical coke or any other partially graphitized carbon, amorphous carbon) such as prebaked consumable carbon anodes used in the process of aluminum smelting.
  • liquid binder is intended to mean a liquid or a colloidal suspension that can bind, at room temperature, following chemical transformations such as reactions, gelling or hydration, a set of particles. The latter, originally in the pulverulent state, are transformed by the action of the liquid binder into a rigid material (non-zero modulus of elasticity).
  • time sufficient is intended to mean the time necessary to obtain the desired drying effect.
  • pressurized is intended to mean to confine the contents (i.e. the coating compositions) under a pressure greater than that of the outside atmosphere especially, for example at a pressure of from about 200 kPa to about 415 kPa. For example, this is achieved by maintaining the coating in a container at the indicated pressure.
  • the term “streamed through gas” is intended to mean that a stream of gas is employed to project the stream of the coating composition.
  • the stream of gas may be air.
  • the pressure of this air stream, streamed through for example a paint gun, may be from about 275 kPa to about 414 kPa.
  • air curtain is intended to mean is a controlled flow of air supplied by a fan powered device which has been designed with an air output of a rectangular shape in order to create a flat pattern and low turbulent air stream with a specific feed rate (e.g. 42 m/s at the contact area).
  • a specific feed rate e.g. 42 m/s at the contact area.
  • an air curtain may be obtained by blowing air through a rectangular groove having dimensions of 10 inches (25.4 cm) and by 0.197 inches (0.5 cm). The velocity of the air jet and the force of the air mass create a high laminar flow at the contact area with the anode surface.
  • gas is intended to mean the fundamental state of matter which is characterized by vast separation of the individual gas particles.
  • gas may mean pure gas, which may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide). It also encompasses gas mixture, such as air, contains a variety of pure gases. In a preferred embodiment, the gas is air.
  • the term “application pattern” is intended to mean the underlying structure that organizes application of the coating compositions in a consistent, regular manner.
  • the application pattern can be described as a repeating unit of shape or form (e.g., a circle, a rectangle), or a determined size (e.g., 8 cm to about 40 cm).
  • displacement velocity is intended to mean a speed or velocity of a vector which points from the initial position of an object (e.g., the stream, the spray gun, the air curtain, or the apparatus for producing an air curtain) to its final position.
  • the standard units of displacement are meters and herein velocity is a vector which shows the direction and rate of motion. According to embodiments, velocity may be of about 35 m/s to about 55 m/s.
  • FIG. 1 illustrates schematically the method of coating according to an embodiment of the present invention.
  • the stream of coating (or coating) and the air curtain are shown as side by side, but as described below in the parameters of the present method, coating stream and air curtain are applied simultaneously such that when the coating contacts the external surface of the carbon material, it is already under the influence of the air curtain that will contribute to its spread across the surface.
  • Fig. 2 illustrates schematically a system air gun-air curtain according to an embodiment of the present invention.
  • Fig. 3 illustrates a representation of a section of a carbon anode selected for the test, to be coated according to an embodiment of the present invention.
  • Fig. 4 illustrates a section of a carbon anode surface coated with an embodiment of the method of the present invention.
  • Fig. 5 illustrates a section of a carbon anode with 3 layers of coating applied.
  • the first layer was applied by the method of the present invention while the second and third layers were applied using a convention spray coating method.
  • Fig. 6 illustrates an air curtain according to an embodiment used in the present invention.
  • Fig. 7 illustrates an air output and rectangular groove as may be used to generate an air curtain according to an embodiment used in the present invention.
  • Fig. 8 Illustrates a system for testing and determination of air velocity at target surface.
  • Fig. 9 illustrates the measured air velocity of air projected from a given distance.
  • Fig. 10 illustrates the manual application of the primer using an airless spraying system.
  • the top panel is a view of the sprayed paint on an anode surface and the bottom view is a zoom on the painted zone showing several unfilled surface cavities.
  • Fig. 11 illustrates an automatic painting system according to an embodiment of the present invention.
  • Fig. 12A is a schematic representation of a top view for the top surface painting by moving both paint gun and blower along the length of the anode, according to an embodiment of the present invention.
  • Fig. 12B is a schematic representation of a side view for the top surface painting by moving both paint gun and blower along the length of the anode, according to an embodiment of the present invention.
  • Fig. 13A is a schematic representation of the paint spray and paint wake orientation with respect to the blower, which shows a view along the anode length, according to an embodiment of the present invention.
  • Fig. 13B is a schematic representation of the paint spray and paint wake orientation with respect to the blower, which shows a view along the anode width, according to an embodiment of the present invention.
  • Fig. 14 illustrates an air gun and blower configuration according to the configuration tested in example 4, according to an embodiment of the present invention.
  • Fig. 15 illustrates side surface painting by moving both paint gun and blower along the length of the anode, according to an embodiment of the present invention.
  • Fig. 16 illustrates an air gun and blower configuration according to the configuration tested in example 5, according to an embodiment of the present invention.
  • Fig. 17A illustrates the appearance of the first tested anode side surface after the first primer layer application in example 5.
  • Fig. 17B illustrates the appearance of the first tested anode side surface after the second primer layer application in example 5.
  • Fig. 17C illustrates the appearance of the first tested anode side surface after the third primer layer application in example 5.
  • Fig. 17D illustrates the appearance of the first tested anode side surface after the fourth primer layer application in example 5.
  • Fig. 18 illustrates the appearance of the first tested anode side surface during primer application in example 5.
  • Fig. 19A illustrates the appearance of the second tested anode side surface during the fourth primer layer application in example 5.
  • Fig. 19B illustrates the appearance of the second tested anode side surface after the fourth primer layer application in example 5.
  • Fig. 20A illustrates the magnified appearance of the painted zone of the second tested anode in example 5 shown in Fig. 19, showing the appearance of the paint wake during the fourth primer layer application.
  • Fig. 20B illustrates the magnified appearance of the painted zone of the second tested anode in example 5 shown in Fig. 19, showing how much the wake allows to completely fill the anode surface cavities and cover its protuberances at least to the naked eye.
  • Fig. 20C illustrates the magnified appearance of the painted zone of the second tested anode in example 5 shown in Fig. 19, showing how much the wake allows to completely fill the anode surface cavities and cover its protuberances at least to the naked eye.
  • Fig. 21 illustrates side surface painting by moving both paint gun and blower along the height of the anode (from top to bottom), according to an embodiment of the present invention.
  • Fig. 22 illustrates an air gun and blower configuration according to the configuration tested in example 6, according to an embodiment of the present invention.
  • Fig. 23A illustrates the appearance of the tested anode side surface zone in example
  • Fig. 23B illustrates the appearance of the tested anode side surface zone in example
  • a method of coating a carbon material with an aqueous priming coating composition for covering an external surface exposed to air of the carbon material, to form a first layer thereon.
  • the aqueous priming coating composition comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water.
  • AI2O3 aluminum oxide
  • the aqueous priming coating composition is described in greater details below.
  • the carbon material is a carbon anode, preferably a prebaked consumable carbon anode.
  • the method of the present invention comprises the step of applying to the external surface a stream of the aqueous priming coating composition pressurized at about 200 to about 415 kPa, or from about 200 to about 400 kPa, or from about 200 to about 350 kPa, or from about 200 to about 300 kPa, or from about 200 to about 250 kPa, or from about 250 to about 415 kPa, or from about 250 to about 400 kPa, or from about 250 to about 350 kPa, or from about 250 to about 300 kPa, or from about 300 to about 415 kPa, or from about 300 to about 400 kPa, or from about 300 to about 350 kPa, or from about 350 to about 415 kPa, or from about 350 to about 400 kPa, or from about 400 to about 415 kPa.
  • the stream of the aqueous priming coating composition is streamed through gas at about 275 kPa to about 414kPa, or from about 275 kPa to about 400 kPa, or from about 275 kPa to about 350 kPa, or about 275 kPa to about 300 kPa, or about 300 kPa to about 414kPa, or from about 300 kPa to about 400 kPa, or from about 300 kPa to about 350 kPa, or about 350 kPa to about 414kPa, or from about 350 kPa to about 400 kPa, or about 400 kPa to about 414kPa..
  • the stream may be applied from a first distance from the external surface of about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, or about 25 cm to about 30 cm, or 8, 10, 15, 20, 25, or 30, and preferably 10 cm.
  • the stream is applied perpendicularly to the external surface of the carbon material.
  • a curtain of air is applied, at a velocity of about 35 m/s to about 55 m/s, or about 35 m/s to about 50 m/s, or about 35 m/s to about 45 m/s, or about 35 m/s to about 40 m/s, or about 40 m/s to about 55 m/s, or about 40 m/s to about
  • 50 m/s or about 50 m/s to about 55 m/s, or about 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, and 55, preferably 42 m/s, also perpendicular to the external surface being coated.
  • the curtain of air is applied from a second distance from the external surface of about 10 mm to about 40 mm, or about 10 mm to about 35 mm, or about 10 mm to about 30 mm, or about
  • the stream of aqueous priming coating composition may comprise an application pattern of from about 8 cm to about 40 cm, or about 8 cm to about 35 cm, or about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, from about 10 cm to about 40 cm, or about 10 cm to about 35 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, from about 15 cm to about 40 cm, or about 15 cm to about 35 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, from about 20 cm to about 40 cm, or about 20 cm to about 20 cm to
  • applying the stream of aqueous priming coating composition may be performed at a flow rate of about 0.4 L/min to about 1 L/min, or about 0.4 L/min to about 0.9 L/min, or about 0.4 L/min to about 0.8 L/min, or about 0.4 L/min to about 0.7 L/min, or about 0.4 L/min to about 0.6L/min, or about 0.4 L/min to about 0.5 L/min, or about 0.5 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.5 L/min to about 0.8 L/min, or about 0.5 L/min to about 0.7 L/min, or about 0.5 L/min to about 0.6L/min, or about 0.6 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.6 L/min to about 0.8 L/min, or about 0.6 L/min to about 0.7 L/min, or about 0.7 L/min, or about 0.5
  • the stream of aqueous priming coating composition and the curtain of air are displaced perpendicular to the external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec, or from about 2 cm/sec to about 18 cm/sec, or from about 2 cm/sec to about 16 cm/sec, or from about 2 cm/sec to about 15 cm/sec, or from about 2 cm/sec to about 14 cm/sec, or from about 2 cm/sec to about 12 cm/sec, or from about 2 cm/sec to about 10 cm/sec, or from about 2 cm/sec to about 8 cm/sec, or from about 2 cm/sec to about 6 cm/sec, or from about 2 cm/sec to about 4 cm/sec, or about 4 cm/sec to about 20 cm/sec, or from about 4 cm/sec to about 18 cm/sec, or from about 4 cm/sec to about 16 cm/sec, or from about 4 cm/sec to about 15 cm/sec, or from about 4 cm/sec to about 14 cm/sec, or from about 4 cm/
  • a distance between a central axis of the stream of aqueous priming coating composition and a central axis of the curtain of air may be from about 100 mm to about 300 mm, or about 100 mm to about 250 mm, or about 100 mm to about 200 mm, or about 100 mm to about 150 mm, or about 100 mm to about 125 mm, or about 125 mm to about 300 mm, or about 125 mm to about 250 mm, or about 125 mm to about 200 mm, or about 125 mm to about 150 mm, or about 150 mm to about 300 mm, or about 150 mm to about 250 mm, or about 150 mm to about 200 mm, or about 200 mm to about 300 mm, or about 200 mm to about 250 mm, or about 250 mm to about 300 mm, or 100, 125, 150, 200, 250, or 300 mm.
  • aqueous priming coating composition refers to an aqueous priming coating composition as disclosed in PCT/CA2018/051083 which is incorporated herein by reference, for application to a carbon material which comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide select from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water.
  • AI2O3 aluminum oxide
  • the aqueous coating of the present invention is preferably applied on an intermediate substrate, such as a priming coating composition described herein.
  • the priming coating composition of the present invention is a formulation of water-based coating (designated aqueous priming coating composition) that highly adheres mechanically on carbon materials, such as anodes, by filling their surface defects, such as open pores and microcracks or microfissures.
  • This coating is preferably containing up to 94 to 96% w/w alumina - aluminum oxide - (on a dry basis).
  • Colloidal binders may be included to act as substrate for the aqueous coating composition.
  • the dissolved salts of sodium and potassium carbonate contained into the aqueous coating composition penetrate the open pores of the aqueous priming coating while most of the lithium salt of carbonate (e.g. U2CO3) from the aqueous coating composition is accumulated on the aqueous priming coating surface.
  • the lithium salt of carbonate e.g. U2CO3
  • the concentration of the calcined aluminum oxide may be from about 32% to 41% w/w, or from about 32% to 40% w/w, or from about 32% to 39% w/w, or from about 32% to 38% w/w, or from about 32% to 37% w/w, or from about 32% to 36% w/w, or from about 32% to 35% w/w, or from about 32% to 34% w/w, or from about 32% to 33% w/w, or from about 33% to 41% w/w, or from about 33% to 40% w/w, or from about 33% to 39% w/w, or from about 33% to 38% w/w, or from about 33% to 37% w/w, or from about 33% to 36% w/w, or from about 33% to 35% w/w, or from about 33% to 34% w/w, or from about 34% to 41% w/w, or from about 34% w/w, or
  • the concentration of reactive aluminum oxide may be from about 6% to 9% w/w, or from about 6% to 8% w/w, or from about 6% to 7% w/w, or from about 7% to 9% w/w, or from about 7% to 8% w/w, or from about 8% to 9% w/w, or from about 7.41 % to 7.99% w/w or 6%, 7%, 8%, 9%, or 7.41% or 7.99% w/w of the aqueous priming coating composition.
  • the concentration of white fused aluminum oxide may be from about
  • the white fused aluminum oxide may have particle size of up to about 0.2 mm and less (i.e., passing across the No. 70 ASTM Tyler Mesh screen).
  • the aqueous priming coating composition may further comprise a calcium salt of carbonate, and the calcium salt of carbonate may be selected from the group consisting of calcium carbonate (CaCC>3), calcium bicarbonate [Ca(HCC>3)2], and combinations thereof.
  • the concentration of the calcium carbonate may be up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 5%, or about 0.5%, 1%, 2%, 3%, 4%, or from about 4% to about 5%, or about 0.5%, 1%, 2%, 3%
  • the concentration of the colloidal silica may be up to 12% w/w, or up to 11 % w/w, or up to 10% w/w, or up to 9% w/w, or up to 8% w/w, or up to 7% w/w, or up to 6% w/w, or up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 12%, or from about 0.5% to about 11%, or from about 0.5% to about 10%, or from about 0.5% to about 9%, or from about 0.5% to about 8%, or from about 0.5% to about 7%, or from about 0.5% to about 6%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 2%
  • the concentration of the colloidal alumina may be up to 14% w/w, or up to 13% w/w, or up to 12% w/w, or up to 11% w/w, or up to 10% w/w, or up to 9% w/w, or up to 8% w/w, or up to 7% w/w, or up to 6% w/w, or up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 14%, or from about 0.5% to about 13%, or from about 0.5% to about 12%, or from about 0.5% to about 11%, or from about 0.5% to about 10%, or from about 0.5% to about 9%, or from about 0.5% to about 8%, or from about 0.5% to about 7%, or from about 0.5% to about 6%, or from about about 0.5% to about a
  • the liquid binder may also comprise a deflocculant, which is a compound that is added to the composition to minimize settling out, prevent flocculation and disperse the other ingredients, increase fluidity of the composition, and help form a colloid or suspension.
  • the deflocculant may be selected from the group consisting of polyethylene glycol graft polymers such as castament® FS10, FS20 or FS60.
  • the deflocculant may be from about 6% to about 10% w/w, or from about 6% to about 9% w/w, or from about 6% to about 8% w/w, or from about 6% to about 7% w/w, or from about 7% to about 10% w/w, or from about 7% to about 9% w/w, or from about 7% to about 8% w/w, or from about 8% to about 10% w/w, or from about 8% to about 9% w/w, or from about 9% to about 10% w/w, or about 7.42% to about 7.64% w/w, or about 6%, 7%, 8%, 9%, 10%, or 7.42%, or 7.64% w/w of the aqueous priming coating composition.
  • the layer of the aqueous priming coating composition on the external surface may have a wet film thickness of about 0.100 mm to about 0.150 mm.
  • multiple applications of the aqueous priming coating composition are made.
  • a second or more layer of the aqueous priming coating composition may be applied by the method of the present invention, by conventional spray coating, or a combination thereof.
  • the aqueous priming coating composition may be dried at room temperature for about 2 minutes or more, prior to application of a subsequent aqueous priming coating composition layer.
  • the external surface when applying the aqueous priming coating composition to the external surface, may have a surface temperature of about 5°C to about 50°C. According to another embodiment, the aqueous priming coating composition may applied at a temperature of about 5°C to about 50°C.
  • the method of the present invention may further comprise applying an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
  • an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
  • aqueous carbonate coating composition or carbonate composition or aqueous coating composition refers to an aqueous coating composition as disclosed in PCT/CA2018/051083 which is incorporated herein by reference, for preventing or reducing air oxidation of a carbon material (for example graphite, petroleum or metallurgical coke or any other partially graphitized carbon, amorphous carbon) comprising an aqueous solution comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate, and water, the aqueous coating having a melting temperature of from about 600°C.
  • a carbon material for example graphite, petroleum or metallurgical coke or any other partially graphitized carbon, amorphous carbon
  • the aqueous coating composition for preventing or reducing air oxidation of a carbon material comprises an aqueous solution comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate, a lithium salt, and water, the aqueous coating having a melting temperature of from about 370°C to about 430°C.
  • an equivalent LhO molar content varying between about 17% and 74% of the composition is added.
  • the equivalent U2O molar content is to be provided by lithium carbonate (U2CO3), lithium bicarbonate (UHCO3), LiF, a mixture of LiF and NaF, or a combination or all of the above, to reach a theoretical melting temperature of 370°C to 430°C, and preferably 400°C, although they have a very low solubility in water.
  • U2CO3 LiF and NaF, the former has the lowest density (2.11 , versus 2.64 and 2.56 g/cm 3 , respectively).
  • U2CO3 leads to the lowest sedimentation rate into concentrated aqueous solutions of Na2CC>3 and K2CO3.
  • An embodiment of the present invention concerns the formulation of a water coating which may be made from a mixture sodium salts of carbonate, potassium salts of carbonate.
  • the sodium salt of carbonate and a potassium salt of carbonate are mixed in quantities that provide an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, to provide an aqueous coating having a melting temperature of up to 600°C.
  • the equivalent molar ratio for sodium and potassium salts of carbonate may be derived according to the following:
  • the equivalent Na20:K20 molar ratio is from about 0.4 to about 2.0, or about 0.4 to about 1.9, or about 0.4 to about 1 .8, or about 0.4 to about 1 .7, or about 0.4 to about
  • Such aqueous coatings comprising the sodium salts and potassium salts of carbonate, such as Na2CC>3, K2CO3, and in the indicated equivalent molar ratio display melting temperatures that may be up to 600°C, such that they can prevent and/or reduce air oxidation from that temperature and above.
  • this invention concerns the formulation of a water coating which may be made from a mixture sodium salts of carbonate, potassium salts of carbonate, and lithium salts.
  • the sodium salt of carbonate and a potassium salt of carbonate are mixed in quantities that provide an equivalent Na20:K20 molar ratio of about 0.4 to about 1.8, to provide an aqueous coating having a melting temperature of between about 370°C and 430°C, and preferably about 400°C.
  • the combination of the sodium salt of carbonate and the potassium salt of carbonate provide an equivalent Na20:K20 molar ratio varying between about 0.4 to about 1.8, or from about 0.4 to about 1.7, or from about 0.4 to about 1.6, or from about 0.4 to about 1 .5, or from about 0.4 to about 1 .4, or from about 0.4 to about 1 .3, or from about 0.4 to about 1 .2, or from about 0.4 to about 1 .0, or from about 0.4 to about 0.9, or from about 0.4 to about 0.8, or from about 0.4 to about 0.7, or from about 0.4 to about 0.6, or from about 0.4 to about 0.5, or from about 0.5 to about 1 .8, or from about 0.5 to about 1.7, or from about 0.5 to about 1 .6, or from about 0.5 to about 1.5, or from about 0.5 to about 1.4, or from about 0.5 to about 1.3, or from about 0.5 to about 1 .2, or from about 0.5 to about 1 .0, or
  • Such aqueous coatings comprising the sodium salts and potassium salts of carbonate, such as Na 2 CC> 3 , K2CO3, in the indicated equivalent molar ratio, and the lithium salt, such as U2CO3, display melting temperatures that may be between about 370°C and 430°C, and preferably about 400°C, such that they can prevent and/or reduce air oxidation from that temperature and above.
  • the sodium salt of carbonate may be selected from the group consisting of sodium carbonate (Na2CC>3), and sodium bicarbonate (NaHCC>3), and combinations thereof.
  • the potassium salt of carbonate may be selected from the group consisting of potassium carbonate (K2CO3), and potassium bicarbonate (KHCO3), and combinations thereof.
  • the combination of a sodium salt of carbonate and a potassium salt of carbonate is a combination of sodium carbonate and potassium carbonate.
  • the combination of a sodium salt of carbonate and a potassium salt of carbonate is a combination of sodium bicarbonate and potassium bicarbonate.
  • the concentration of sodium carbonate may be from about 7% to about 17% w/w, or from about 7% to about 16% w/w, or from about 7% to about 15% w/w, or from about 7% to about 14% w/w, or from about 7% to about 13% w/w, or from about 7% to about 12% w/w, or from about 7% to about 11% w/w, or from about 7% to about 10% w/w, or from about 7% to about 9% w/w, or from about 7% to about 8% w/w, or 8% to about 17% w/w, or from about 8% to about 16% w/w, or from about 8% to about 15% w/w, or from about 8% to about 14% w/w, or from about 8% to about 13% w/w, or from about 8% to about 12% w/w, or from about 8% to about 11% w/w, or from about 8%
  • the concentration of sodium bicarbonate may be from about 11% to about 31% w/w, or from about 11% to about 30% w/w, or from about 11% to about 29% w/w, or from about 11% to about 28% w/w, or from about 11% to about 27% w/w, or from about 11% to about 26% w/w, or from about 11% to about 25% w/w, or from about 11% to about 24% w/w, or from about 11% to about 23% w/w, or from about 11% to about 22% w/w, or from about 11% to about 21% w/w, or from about 11% to about 20% w/w, or from about 11% to about 19% w/w, or from about 11% to about 18% w/w, or from about 11% to about 17% w/w, or from about 11% to about 16% w/w, or from about 11% to about 15% w/w, or from about 11% to about 31% w/
  • the concentration of potassium carbonate may be from about 15% to about 25% w/w, or from about 15% to about 24% w/w, or from about 15% to about 23% w/w, or from about 15% to about 22% w/w, or from about 15% to about 21% w/w, or from about 15% to about 20% w/w, or from about 15% to about 19% w/w, or from about 15% to about 18% w/w, or from about 15% to about 17% w/w, or from about 15% to about 16% w/w, or from about 16% to about 25% w/w, or from about 16% to about 24% w/w, or from about 16% to about 23% w/w, or from about 16% to about 22% w/w, or from about 16% to about 21% w/w, or from about 16% to about 20% w/w, or from about 16% to about 19% w/w, or from about 16% to about 18% w/w, or or
  • the concentration of potassium bicarbonate may be from about 19% to about 43% w/w, or from about 19% to about 42% w/w, or from about 19% to about 41% w/w, or from about 19% to about 40% w/w, or from about 19% to about 39% w/w, or from about 19% to about 38% w/w, or from about 19% to about 37% w/w, or from about 19% to about 36% w/w, or from about 19% to about 35% w/w, or from about 19% to about 34% w/w, or from about 19% to about 33% w/w, or from about 19% to about 32% w/w, or from about 19% to about 31% w/w, or from about 19% to about 30% w/w, or from about 19% to about 29% w/w, or from about 19% to about 28% w/w, or from about 19% to about 27% w/w, or from
  • the equivalent U2O molar content should be between about 17% and about 74% of the composition.
  • the equivalent U2O molar content may be provided from a lithium salt which may be selected from the group consisting of lithium carbonate (U2CO3), lithium bicarbonate (UHCO3), LiF, a mixture of LiF and NaF, and combination of all of the above.
  • the equivalent molar ratio for lithium salts may be derived according to the following:
  • U2CO3 U2O + C0 2 de U2O equivalent 2
  • the equivalent U2O molar content may be from about 17% to about 74% of the composition, or from about 20% to about 74%, or from about 25% to about 74%, or from about 30% to about 74%, or from about 35% to about 74%, or from about 40% to about 74%, or from about 45% to about 74%, or from about 50% to about 74%, or from about 55% to about 74%, or from about 60% to about 74%, or from about 65% to about 74%, or from about 70% to about 74%, or from 17% to about 70%, or from about 20% to about 70%, or from about 25% to about 70%, or from about 30% to about 70%, or from about 35% to about 70%, or from about 40% to about 70%, or from about 45% to about 70%, or from about 50% to about 70%, or from about 55% to about 70%, or from about 60% to about 70%, or from about 65% to about 70%, or from 17% to about 65%, or from about 20% to about 65%, or from about 25% to about 65%, or from about 30% to about 70%, or
  • the lithium salt is lithium carbonate.
  • the lithium carbonate may be in suspension in the aqueous coating composition.
  • the lithium carbonate may be any powdered form of lithium carbonate. However, smaller particles may be used in order to favor the homogeneity of the suspension. For example, nano-sized particles of lithium carbonate may be used to obtain stable suspensions.
  • Lithium bicarbonate may also be used in the composition of the present invention. It is however mostly available in solution form at maximum concentration of 5.39% w/w.
  • the concentration of the lithium carbonate may be from about 8% to about 18% w/w, or from about 8% to about 17% w/w, or from about 8% to about 16% w/w, or from about 8% to about 15% w/w, or from about 8% to about 14% w/w, or from about 8% to about 13% w/w, or from about 8% to about 12% w/w, or from about 8% to about 11% w/w, or from about 8% to about 10% w/w, or from about 8% to about 9% w/w, or from about 9% to about 18% w/w, or from about 9% to about 17% w/w, or from about 9% to about 16% w/w, or from about 9% to about 15% w/w, or from about 9% to about 14% w/w, or from about 9% to about 13% w/w, or from about 9% to about 12% w/w, or from about
  • the LiF or LiF mixed with NaF may be used as salts of lithium according to concentrations that provide the adequate equivalent U2O molar content.
  • the aqueous coating of the present invention may further comprise a liquid binder.
  • a liquid binder means a liquid or a colloidal suspension that can, bind at room temperature, following chemical transformations such as reactions, gelling or hydration, a set of particles. The latter, originally in the pulverulent state, are transformed by the action of the liquid binder into a rigid material (non-zero modulus of elasticity).
  • the liquid binder may comprise colloidal silica, colloidal alumina, a deflocculant and combinations thereof.
  • the concentration of colloidal silica may be up to 5% w/w, or up to
  • the concentration of colloidal alumina may be up to 8% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 5%, or about 0.5%, 1%, 2%, 3%, 4%, 5%, or 0.65% w/w of the aqueous coating composition.
  • the concentration of colloidal alumina may be up
  • w/w 7% w/w, or up to 6% w/w, or up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 8%, or from about 0.5% to about 7%, or from about 0.5% to about 6%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 8%, or from about 1% to about 7%, or from about 1% to about 6%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 8%, or from about 2% to about 7%, or from about 2% to about
  • the liquid binder may also comprise a deflocculant, which is a compound that is added to the composition to minimize settling out, prevent flocculation and disperse the other ingredients, increase fluidity of the composition, and help form a colloid or suspension.
  • the deflocculant may be selected from the group consisting of polyethylene glycol graft polymers, such as castament® FS10, FS20 or FS60.
  • the concentration of the deflocculant may be up to 6% w/w, or up to
  • the layer aqueous coating composition may have a wet film thickness of about 0.15 mm to about 0.50 mm, or a wet film thickness of about 0.25 ⁇ 0.05 mm. In embodiments, the layer aqueous coating composition may have a residual water content of about 12% w/w or less.
  • a method of coating a carbon material with a chemical treatment for preventing or reducing air oxidation of the carbon material comprising a first layer comprising an aqueous priming coating composition covering an external surface exposed to air of the carbon material; and a second layer, covering the first layer, comprising an aqueous coating composition.
  • the aqueous priming coating composition comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water, as detailed above.
  • AI2O3 aluminum oxide
  • the aqueous priming coating composition comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water, as detailed above.
  • the aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C.
  • the dry layer when applying the aqueous coating composition to the dry layer, has a surface temperature of about 74°C to about 100°C. In embodiments, the aqueous coating composition is applied at a temperature of about 48°C to about 52°C.
  • a system for coating a carbon material with a fluid coating composition for covering an external surface exposed to air of the carbon material comprises a spray gun, and an apparatus for producing an air curtain.
  • the spray gun is configured to apply to the external surface a stream of fluid coating composition pressurized at about 200 to about 415 kPa, or from about 200 to about 400 kPa, or from about 200 to about 350 kPa, or from about 200 to about 300 kPa, or from about 200 to about 250 kPa, or from about 250 to about 415 kPa, or from about 250 to about 400 kPa, or from about 250 to about 350 kPa, or from about 250 to about 300 kPa, or from about 300 to about 415 kPa, or from about 300 to about 400 kPa, or from about 300 to about 350 kPa, or from about 350 to about 415 kPa, or from about 350 to about 400 kPa, or from about 400 to about 415 kPa.
  • the fluid coating composition may be streamed through gas at about 275 kPa to about 414kPa, or from about 275 kPa to about 400 kPa, or from about 275 kPa to about 350 kPa, or about 275 kPa to about 300 kPa, or about 300 kPa to about 414kPa, or from about 300 kPa to about 400 kPa, or from about 300 kPa to about 350 kPa, or about 350 kPa to about 414kPa, or from about 350 kPa to about 400 kPa, or about 400 kPa to about 414kPa.
  • the fluid coating composition may be streamed through a paint gun configured to stream of air at the indicated pressure.
  • the spray gun may be positioned at a first distance from said external surface of about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, or about 25 cm to about 30 cm, or 8, 10, 15, 20, 25, or 30, perpendicular to said external surface.
  • the apparatus for producing an air curtain is configured to apply a curtain of air at a velocity of about 35 m/s to about 55 m/s, or about 35 m/s to about 50 m/s, or about 35 m/s to about 45 m/s, or about 35 m/s to about 40 m/s, or about 40 m/s to about 55 m/s, or about 40 m/s to about
  • 50 m/s or about 50 m/s to about 55 m/s, or about 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, and 55, also perpendicular to the external surface being coated.
  • the curtain of air is applied from a second distance from the external surface of about 10 mm to about 40 mm, or about 10 mm to about 35 mm, or about 10 mm to about 30 mm, or about
  • the system is configured for application of the fluid coating composition as a stream under pressure simultaneously with the air curtain, to provide an even distribution of the fluid coating composition.
  • the spray gun may provide an application pattern of from about 8 cm to about 40 cm, or about 8 cm to about 35 cm, or about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, from about 10 cm to about 40 cm, or about 10 cm to about 35 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, from about 15 cm to about 40 cm, or about 15 cm to about 35 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, from about 20 cm to about 40 cm, or about 20 cm to about 35 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, from about 25 cm to about 40 cm, or about 25 cm to about 35 cm, or about 25 cm to about 30 cm, or from about 20 cm to about 25 cm,
  • applying the stream of fluid coating composition may be performed at a flow rate of about 0.4 L/min to about 1 L/min, or about 0.4 L/min to about 0.9 L/min, or about 0.4 L/min to about 0.8 L/min, or about 0.4 L/min to about 0.7 L/min, or about 0.4 L/min to about 0.6L/min, or about 0.4 L/min to about 0.5 L/min, or about 0.5 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.5 L/min to about 0.8 L/min, or about 0.5 L/min to about 0.7 L/min, or about 0.5 L/min to about 0.6L/min, or about 0.6 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.6 L/min to about 0.8 L/min, or about 0.6 L/min to about 0.7 L/min, or about 1 L/min, or about 0.5 L/min to about
  • the spray gun and the apparatus for producing an air curtain are displaced perpendicular to the external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec, or from about 2 cm/sec to about 18 cm/sec, or from about 2 cm/sec to about 16 cm/sec, or from about 2 cm/sec to about 15 cm/sec, or from about 2 cm/sec to about 14 cm/sec, or from about 2 cm/sec to about 12 cm/sec, or from about 2 cm/sec to about 10 cm/sec, or from about 2 cm/sec to about 8 cm/sec, or from about 2 cm/sec to about 6 cm/sec, or from about 2 cm/sec to about 4 cm/sec, or about 4 cm/sec to about 20 cm/sec, or from about 4 cm/sec to about 18 cm/sec, or from about 4 cm/sec to about 16 cm/sec, or from about 4 cm/sec to about 15 cm/sec, or from about 4 cm/sec to about 14 cm/sec, or from about 4 cm/sec to about 12 cm
  • a distance between a central axis of the spray gun and a central axis of the apparatus for producing an air curtain may be from about 100 mm to about 300 mm, or about 100 mm to about 250 mm, or about 100 mm to about 200 mm, or about 100 mm to about 150 mm, or about 100 mm to about 125 mm, or about 125 mm to about 300 mm, or about 125 mm to about 250 mm, or about 125 mm to about 200 mm, or about 125 mm to about 150 mm, or about 150 mm to about 300 mm, or about 150 mm to about 250 mm, or about 150 mm to about 200 mm, or about 200 mm to about 300 mm, or about 200 mm to about 250 mm, or about 250 mm to about 300 mm, or 100, 125, 150, 200, 250, or 300 mm.
  • the system of the present invention may further comprise a fluid coating composition reservoir, in fluid communication with said spray gun.
  • the fluid coating composition reservoir is a high-pressure reservoir.
  • the fluid coating composition reservoir may further comprises an agitator.
  • system of the present invention may further comprise a compressor in fluid communication with the apparatus for producing an air curtain, to provide compressed air thereto.
  • system of the present invention may further comprise an air dehumidifier.
  • the fluid coating composition may be an aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water, as described above.
  • AI2O3 aluminum oxide
  • the fluid coating composition may be an aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water, as described above.
  • the fluid coating composition may be an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C, which may be applied over a dry layer of the aqueous priming coating composition described above.
  • FIG. 1 illustrates schematically the method of coating according to an embodiment of the present invention.
  • the stream of coating 20 and the air curtain 18 are shown as side by side, but as described below in the parameters of the present method, coating stream and air curtain are applied simultaneously such that when the coating contacts the external surface (i.e. coated anode 12) of the carbon material (anode 10), it is already under the influence of the air curtain that will contribute to its spread across the surface.
  • the coating may be applied to the surface with a conventional spray gun 16 by mixing the coating at 30 to 40 psi, preferably 30 psi (i.e. 200 to about 280 kPa) of pressure with streaming of gas (i.e. air) current at a pressures (e.g. about 275 kPa to about 414 kPa).
  • the coating pressure is set at these values to produce a layer with a wet film thickness of about 0.125 mm.
  • the spray gun 16 may be placed perpendicularly to and about 10 cm (4 inches) from the surface. These specific parameters produce a lightly dense stream of coating that drips on the surface of the carbon anode 10, simulating a coating shower.
  • an air output is located at 5 inches (about 12.7 cm) from the air gun (although it could be located anywhere near the air-gun, as long at the stream of coating 20 is avoided) and at about 2 inches (about 5.1 cm) from the anode surface (although this distance could be varied, as long as the targeted air velocity of 35 m/s to 45 m/s, preferably 42 m/s is obtained near the surface of the carbon anode 10), resulting in a system formed by the air gun and the air output.
  • the air output is connected to an air blower that supplies the air so that the speed at the contact area with the external surface of the carbon anode 10 is close to 42 m/s.
  • the air curtain 18 is blown perpendicularly to the carbon anode 10 surface through a rectangular groove 22. See Fig. 2.
  • one face of the anode was selected as a sample.
  • the top section is notably more porous than the others faces of the carbon anode 10; it also shows in most of the cases the very uneven structure of pores.
  • the system moves parallel to the carbon anode 10 face selected.
  • the parameters for the air gun were set so that the fan width was about 6 inches. Additionally, the air output had a length of 10 inches, and it was placed centered with the gun to ensure that one third of the section of the face was covered with one pass as is shown in Fig. 3.
  • the air gun is turned on at the edge of the face.
  • the air curtain that is simultaneously applied forces the coating stream to flow into the pores, waves and asperities of the carbon anode 10 and spreads evenly on the surface. While the system moves along the surface, this effect is reproduced until a thin uniform layer of coating is achieved all over the surface section.
  • Fig. 4 a close up of the coated surface can be seen.
  • wet film thickness of the layers was measured using a wet film thickness gauge (Wet Film Thickness Gauge, Dual Scale Micron & Mils). The results showed a thickness from 0.100 to 0.150 mm, which indicates a wet film thickness that approaches greatly to the one required.
  • Fig. 6 illustrates an air curtain according to a prototypical embodiment of such curtain.
  • Fig. 7 illustrates an air output device comprising a rectangular groove through which such an air curtain may be obtained.
  • Fig. 8 there is shown a system for determination of the distance between a source of air to obtain an appropriate air velocity at the contact area. The air speed was measured in 3 different points with an anemometer: center (c) and two sides (S1 and S2, as shown in Fig. 6) at 3 different distances (here, 2, 4 or 6 inches - 5.08, 10.16 and 15.24 cm) and the flow of air is profiled.
  • Fig. 9 shows the profiled velocities.
  • a conventional commercial airless spraying system 100 is used for applying manually three layers of primer on a carbon anode 10 surface (Fig. 10, Top).
  • the total primer wet thickness was about 0.5 mm and its appearance after application of the third (last) layer is shown on Fig. 10, bottom.
  • the surface 10 With such conventional painting technique and heterogeneous material (i.e., the surface 10), it is not possible to fill and cover all surface defects, such as cavities (see Fig. 1 , bottom, unfilled cavities 110), even when increasing the paint final film thickness up to 1 - 1.5 mm.
  • this conventional technique does not allow the application of a 0,5 mm thick primer coat in only a single or two layers without causing paint loss by dripping of more than 10 wt. %.
  • an automatic painting system of the present invention was used for applying the primer on the top surface of carbon anodes 10 (see Fig. 11).
  • This system uses an automatic paint gun 111 (a BINKS “TROPHY” SERIES AUTOMATIC SPRAY GUNS, from Carlisle), having the specifications in Table 2 below. It is connected to a high- pressure tank with agitator 113 (such as model 236153 from Graco) that contains the primer.
  • agitator 113 such as model 236153 from Graco
  • the system also uses a “WindJet Air Knife” blower 112 to provide an air curtain.
  • the air curtain follows the paint gun 111 during its displacement along the length of the anode 10 (see Fig. 12A and 12B) at constant velocity.
  • the air curtain creates a wake of paint moving at the same velocity as the paint gun 111 on the anode 10 surface, ahead of the blower 112 air slot (see Figs. 13A and 13B).
  • the amount of paint locally carried out by this wake must be just sufficient for filling and/or covering all surface cavities and/or protuberances that can be detected by the naked eye.
  • the blower 112 also increases paint drying rate after each applied layer.
  • Table 3 painting set-up parameters [00191] These parameters allowed to reach an average 0.5 mm thick primer coating on the anode top surface test zone after application of 4 layers.
  • the paint wake ahead of the blower 112 air slot that started to form during application of the fourth layer completely filled the anode 10 surface cavities and also covered its protuberances, at least to the naked eye. Paint loss by dripping was less than 10% wt.
  • the appearance of the final primer coating was similar to that shown on Fig. 11.
  • the automatic painting novel system described in example 3 was used to apply the primer on a side surface of two carbon anodes by moving both paint gun and blower along their length (see Fig. 15).
  • the distance between the paint gun 111 and the blower 112, as well as their position with respect to the anode side surface were in both cases as shown on Fig. 16.
  • the other painting set-up parameters were the same as those given in example 2 except the air gun and blower displacement velocity as shown below.
  • Fig. 21 - 23 the novel automatic painting system described in example 3 was used for applying the primer on a side surface of a carbon anode 10 by moving both paint gun 111 and blower 112 from bottom to top (see Fig. 21).
  • the paint application procedure started at the left side of the anode 10 and was then repeated at different positions toward the right side of anode 10. Paint overlapping between each position was about 50%.
  • the distance between the paint gun and the blower as well as their position with respect to the anode side surface were as shown on Fig. 22.
  • the other painting set-up parameters were the same as those given in examples 2 and 3 except the air gun and blower displacement velocity as shown below:

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Abstract

The present document describes methods of coating a carbon material with an aqueous priming coating composition for covering an external surface exposed to air of the carbon material to form a first layer thereon. The method comprises applying to the external surface a stream of aqueous priming coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa. Also described are systems for coating a carbon material with a fluid coating composition.

Description

METHOD OF COATING A CARBON SURFACE
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of US provisional patent application No. 62/980,551 filed on February 24, 2020, the specification of which is hereby incorporated by reference in its entirety.
BACKGROUND
(at Field
[0002] The subject matter disclosed generally relates to methods of coating a carbon material, and more particularly to methods of coating a carbon material with an aqueous priming coating composition for covering surfaces of said carbon materials to form a first layer thereon.
(b) Related Prior Art
[0003] Coating a substrate can be thought of as a simple and common task. Beyond all the variables to be considered in the coating process, standard procedures and methods have been developed over the years according to many different applications required in the market. However, when developing a new product or process, each variable must be taken into account to select the best method, perform it in the most effective way and accomplish the desired duty.
[0004] In the instant case, coating carbon materials such as a prebaked carbon anode using a rapid and effective method is required for use in an automated and industrialized setting.
[0005] Some factors are critical to consider in the development of this method. Firstly, a key factor is the type of substrate to be coated. Carbon surfaces, in particular prebaked carbon anodes have a very particular surface due to their manufacturing process. No one side of such anodes is similar to the other. In fact, each anode face may contain variations of waviness and roughness, with diverse heights and widths such that it difficult to define an even profile for carbon anode surfaces. The disparity of the roughness results in several pores and asperities of very different structures over the total surface area, making the surface of the anode a highly porous and uneven substrate.
[0006] Secondly, carbon anode surfaces possess what could be termed a partial wetting surface that requires the application of a large amount of energy from a liquid to break the high energy that is intrinsic to the surface.
[0007] On the other hand, when the coating is applied to the anode substrate, it shows a typical behaviour of a liquid with high cohesion force, which results in the coating intending to keep its droplet shape instead of spreading easily onto and into the surface; so it may be said that the carbon anode surface energy is weaker than the surface tension of the coating. [0008] As a consequence, the interaction between the carbon anode and the coating is not strong enough to reach the necessary level of interfacial tension between the carbon anode and the coating, which leads to a poor wettability from the anode surface and therefore creates a challenge when applying the coating directly to the carbon surface.
[0009] Therefore, there is a need for processes for coating carbon surfaces, particularly carbon anode surfaces.
[0010] After experimenting with many different coating techniques and methods, the method described herein has been developed to mitigate the difficulties mentioned above.
SUMMARY
[0011] According to an embodiment, there is provided a method of coating a carbon material with an aqueous priming coating composition for covering an external surface exposed to air of said carbon material, to form a first layer thereon, the aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water; the method comprising the step of applying to said external surface a stream of said aqueous priming coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa, from a first distance from said external surface of about 8 cm to about 30 cm, perpendicular to said external surface, and simultaneously applying a curtain of air at a velocity of about 35 m/s to about 55 m/s, from a second distance from said external surface of about 10 mm to about 40 mm perpendicular to said external surface, wherein application of said aqueous priming coating composition as a stream under pressure simultaneously with said air curtain provides an even distribution of said aqueous priming coating composition over said external surface.
[0012] The carbon material may be a carbon anode.
[0013] The carbon anode may be a prebaked consumable carbon anode.
[0014] The layer of said aqueous priming coating composition on said external surface may have a wet film thickness of about 0.100 mm to about 0.50 mm.
[0015] The layer of said aqueous priming coating composition on said external surface may have a wet film thickness of about 0.100 mm to about 0.150 mm. [0016] The stream of said aqueous priming coating composition may comprise an application pattern of from about 8 cm to about 40 cm.
[0017] The application pattern may be from about 20 cm to about 35 cm.
[0018] Applying said stream of said aqueous priming coating composition may be at a flow rate of about 0.4 L/min to about 1 L/min. The flow rate may be of about 0.55 L/min.
[0019] The velocity may be from about 45 m/s to about 50 m/s. The velocity may be about
42 m/s.
[0020] The stream of said aqueous priming coating composition and said curtain of air may be displaced perpendicular to said external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec.
[0021] The displacement velocity may be from about 4 to about 17 cm/sec.
[0022] Multiple applications of said aqueous priming coating composition may be made.
[0023] The aqueous priming coating composition may be dried at room temperature for about 2 minutes or more, prior to application of a subsequent aqueous priming coating composition layer.
[0024] When applying said aqueous priming coating composition to said external surface, said external surface may have a surface temperature of about 5°C to about 50°C.
[0025] The aqueous priming coating composition may be applied at a temperature of about
5°C to about 50°C.
[0026] The aqueous priming coating composition may be streamed through gas at about 275 kPa.
[0027] The first distance from said external surface may be of about 15 cm to about 20 cm.
The first distance from said external surface may be of about 10 cm.
[0028] The second distance from said external surface may be of about 13 mm to about 30 mm.
[0029] The distance between a central axis of said stream of said aqueous priming coating composition and a central axis of said curtain of air may be from about 100 mm to about 300 mm. The distance may be from about 125 mm to about 200 mm.
[0030] The method may further comprise applying an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
[0031] The aqueous coating composition may form a layer having a wet film thickness of about 0.15 mm to about 0.50 mm.
[0032] The aqueous coating composition may form a layer having a wet film thickness of about 0.25 ± 0.05 mm.
[0033] When applying the aqueous coating composition to said dry layer, said dry layer may have a surface temperature of about 74°C to about 100°C.
[0034] The aqueous coating composition may be applied at a temperature of about 48°C to about 52°C.
[0035] The second or more layer of said aqueous priming coating composition may be applied by the method of claim 1 , by spray coating, or a combination thereof.
[0036] According to another embodiment, there is provided a system for coating a carbon material with a fluid coating composition for covering an external surface exposed to air of said carbon material, comprising: a) a spray gun, configured to apply to said external surface a stream of fluid coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa, said spray gun positioned at a first distance from said external surface of about 8 cm to about 30 cm, perpendicular to said external surface, b) an apparatus for producing an air curtain, configured to apply a curtain of air at a velocity of about 35 m/s to about 55 m/s, from a second distance from said external surface of about 10 mm to about 40 mm perpendicular to said external surface, wherein said system may be configured for application of said fluid coating composition as a stream under pressure simultaneously with said air curtain, to provide an even distribution of said fluid coating composition.
[0037] The system may further comprise a fluid coating composition reservoir, in fluid communication with said spray gun. The fluid coating composition reservoir may be a high-pressure reservoir. The fluid coating composition reservoir may further comprise an agitator.
[0038] The system may further comprise a compressor in fluid communication with said apparatus for producing an air curtain, to provide compressed air thereto. [0039] The system may further comprise an air dehumidifier.
[0040] The spray gun may provide an application pattern of from about 8 cm to about 40 cm.
[0041] The application pattern may be from about 20 cm to about 35 cm.
[0042] When applying said stream of said aqueous priming coating composition may be provided at a flow rate of about 0.4 L/min to about 1 L/min. The flow rate may be of about 0.55 L/min.
[0043] The velocity may be from about 45 m/s to about 50 m/s. The velocity may be about
42 m/s.
[0044] The spray gun and said apparatus for producing an air curtain may be displaced perpendicular to said external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec.
[0045] The displacement velocity may be from about 4 cm/sec to about 17 cm/sec.
[0046] The spray gun may be configured to stream through gas at about 275 kPa.
[0047] The first distance from said external surface may be of about 15 cm to about 20 cm.
[0048] The first distance from said external surface may be of about 10 cm.
[0049] The second distance from said external surface may be of about 13 mm to about 30 mm.
[0050] The distance between a central axis of said spray gun and a central axis of said apparatus for producing an air curtain may be from about 100 mm to about 300 mm. The distance may be from about 125 mm to about 200 mm.
[0051] The fluid coating composition may be an aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water.
[0052] The fluid coating composition may be an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of said aqueous priming coating composition.
[0053] The following terms are defined below. [0054] The term “solution” is intended to mean a homogeneous mixture composed of two or more substances. Also, as used herein, the term aqueous solution is when one of the solvents is water. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. The mixing process of a solution happens at a scale where the effects of chemical polarity are involved, resulting in interactions that are specific to solvation. The solution assumes the phase of the solvent when the solvent is the larger fraction of the mixture, as is commonly the case. The concentration of a solute in a solution is the mass of that solute expressed as a percentage of the mass of the whole solution.
[0055] The term “carbon material” is intended to mean an object or item that is made from carbon (i.e., graphite, petroleum or metallurgical coke or any other partially graphitized carbon, amorphous carbon) such as prebaked consumable carbon anodes used in the process of aluminum smelting.
[0056] The term “liquid binder” is intended to mean a liquid or a colloidal suspension that can bind, at room temperature, following chemical transformations such as reactions, gelling or hydration, a set of particles. The latter, originally in the pulverulent state, are transformed by the action of the liquid binder into a rigid material (non-zero modulus of elasticity).
[0057] The term “time sufficient” is intended to mean the time necessary to obtain the desired drying effect.
[0058] The term “pressurized” is intended to mean to confine the contents (i.e. the coating compositions) under a pressure greater than that of the outside atmosphere especially, for example at a pressure of from about 200 kPa to about 415 kPa. For example, this is achieved by maintaining the coating in a container at the indicated pressure.
[0059] The term “streamed through gas” is intended to mean that a stream of gas is employed to project the stream of the coating composition. For example, the stream of gas may be air. The pressure of this air stream, streamed through for example a paint gun, may be from about 275 kPa to about 414 kPa.
[0060] The term “air curtain” is intended to mean is a controlled flow of air supplied by a fan powered device which has been designed with an air output of a rectangular shape in order to create a flat pattern and low turbulent air stream with a specific feed rate (e.g. 42 m/s at the contact area). For example, an air curtain may be obtained by blowing air through a rectangular groove having dimensions of 10 inches (25.4 cm) and by 0.197 inches (0.5 cm). The velocity of the air jet and the force of the air mass create a high laminar flow at the contact area with the anode surface. [0061] The term “gas” is intended to mean the fundamental state of matter which is characterized by vast separation of the individual gas particles. As used herein, the term gas may mean pure gas, which may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide). It also encompasses gas mixture, such as air, contains a variety of pure gases. In a preferred embodiment, the gas is air.
[0062] The term “application pattern” is intended to mean the underlying structure that organizes application of the coating compositions in a consistent, regular manner. The application pattern can be described as a repeating unit of shape or form (e.g., a circle, a rectangle), or a determined size (e.g., 8 cm to about 40 cm).
[0063] The term “displacement velocity” is intended to mean a speed or velocity of a vector which points from the initial position of an object (e.g., the stream, the spray gun, the air curtain, or the apparatus for producing an air curtain) to its final position. The standard units of displacement are meters and herein velocity is a vector which shows the direction and rate of motion. According to embodiments, velocity may be of about 35 m/s to about 55 m/s.
[0064] Features and advantages of the subject matter hereof will become more apparent in light of the following detailed description of selected embodiments, as illustrated in the accompanying figures. As will be realized, the subject matter disclosed and claimed is capable of modifications in various respects, all without departing from the scope of the claims. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive and the full scope of the subject matter is set forth in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0065] Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
[0066] Fig. 1 illustrates schematically the method of coating according to an embodiment of the present invention. The stream of coating (or coating) and the air curtain are shown as side by side, but as described below in the parameters of the present method, coating stream and air curtain are applied simultaneously such that when the coating contacts the external surface of the carbon material, it is already under the influence of the air curtain that will contribute to its spread across the surface.
[0067] Fig. 2 illustrates schematically a system air gun-air curtain according to an embodiment of the present invention. [0068] Fig. 3 illustrates a representation of a section of a carbon anode selected for the test, to be coated according to an embodiment of the present invention.
[0069] Fig. 4 illustrates a section of a carbon anode surface coated with an embodiment of the method of the present invention.
[0070] Fig. 5 illustrates a section of a carbon anode with 3 layers of coating applied. The first layer was applied by the method of the present invention while the second and third layers were applied using a convention spray coating method.
[0071] Fig. 6 illustrates an air curtain according to an embodiment used in the present invention.
[0072] Fig. 7 illustrates an air output and rectangular groove as may be used to generate an air curtain according to an embodiment used in the present invention.
[0073] Fig. 8 Illustrates a system for testing and determination of air velocity at target surface.
[0074] Fig. 9 illustrates the measured air velocity of air projected from a given distance.
[0075] Fig. 10 illustrates the manual application of the primer using an airless spraying system. The top panel is a view of the sprayed paint on an anode surface and the bottom view is a zoom on the painted zone showing several unfilled surface cavities.
[0076] Fig. 11 illustrates an automatic painting system according to an embodiment of the present invention.
[0077] Fig. 12A is a schematic representation of a top view for the top surface painting by moving both paint gun and blower along the length of the anode, according to an embodiment of the present invention.
[0078] Fig. 12B is a schematic representation of a side view for the top surface painting by moving both paint gun and blower along the length of the anode, according to an embodiment of the present invention.
[0079] Fig. 13A is a schematic representation of the paint spray and paint wake orientation with respect to the blower, which shows a view along the anode length, according to an embodiment of the present invention.
[0080] Fig. 13B is a schematic representation of the paint spray and paint wake orientation with respect to the blower, which shows a view along the anode width, according to an embodiment of the present invention. [0081] Fig. 14 illustrates an air gun and blower configuration according to the configuration tested in example 4, according to an embodiment of the present invention.
[0082] Fig. 15 illustrates side surface painting by moving both paint gun and blower along the length of the anode, according to an embodiment of the present invention.
[0083] Fig. 16 illustrates an air gun and blower configuration according to the configuration tested in example 5, according to an embodiment of the present invention.
[0084] Fig. 17A illustrates the appearance of the first tested anode side surface after the first primer layer application in example 5.
[0085] Fig. 17B illustrates the appearance of the first tested anode side surface after the second primer layer application in example 5.
[0086] Fig. 17C illustrates the appearance of the first tested anode side surface after the third primer layer application in example 5.
[0087] Fig. 17D illustrates the appearance of the first tested anode side surface after the fourth primer layer application in example 5.
[0088] Fig. 18 illustrates the appearance of the first tested anode side surface during primer application in example 5.
[0089] Fig. 19A illustrates the appearance of the second tested anode side surface during the fourth primer layer application in example 5.
[0090] Fig. 19B illustrates the appearance of the second tested anode side surface after the fourth primer layer application in example 5.
[0091] Fig. 20A illustrates the magnified appearance of the painted zone of the second tested anode in example 5 shown in Fig. 19, showing the appearance of the paint wake during the fourth primer layer application.
[0092] Fig. 20B illustrates the magnified appearance of the painted zone of the second tested anode in example 5 shown in Fig. 19, showing how much the wake allows to completely fill the anode surface cavities and cover its protuberances at least to the naked eye.
[0093] Fig. 20C illustrates the magnified appearance of the painted zone of the second tested anode in example 5 shown in Fig. 19, showing how much the wake allows to completely fill the anode surface cavities and cover its protuberances at least to the naked eye.
[0094] Fig. 21 illustrates side surface painting by moving both paint gun and blower along the height of the anode (from top to bottom), according to an embodiment of the present invention. [0095] Fig. 22 illustrates an air gun and blower configuration according to the configuration tested in example 6, according to an embodiment of the present invention.
[0096] Fig. 23A illustrates the appearance of the tested anode side surface zone in example
6, prior to painting completion at the last most right anode position.
[0097] Fig. 23B illustrates the appearance of the tested anode side surface zone in example
6, after painting completion at the last most right anode position.
[0098] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
DETAILED DESCRIPTION
[0099] In embodiments there is disclosed a method of coating a carbon material with an aqueous priming coating composition for covering an external surface exposed to air of the carbon material, to form a first layer thereon. The aqueous priming coating composition comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water. The aqueous priming coating composition is described in greater details below.
[00100] In embodiments, the carbon material is a carbon anode, preferably a prebaked consumable carbon anode.
[00101] The method of the present invention comprises the step of applying to the external surface a stream of the aqueous priming coating composition pressurized at about 200 to about 415 kPa, or from about 200 to about 400 kPa, or from about 200 to about 350 kPa, or from about 200 to about 300 kPa, or from about 200 to about 250 kPa, or from about 250 to about 415 kPa, or from about 250 to about 400 kPa, or from about 250 to about 350 kPa, or from about 250 to about 300 kPa, or from about 300 to about 415 kPa, or from about 300 to about 400 kPa, or from about 300 to about 350 kPa, or from about 350 to about 415 kPa, or from about 350 to about 400 kPa, or from about 400 to about 415 kPa.
[00102] The stream of the aqueous priming coating composition is streamed through gas at about 275 kPa to about 414kPa, or from about 275 kPa to about 400 kPa, or from about 275 kPa to about 350 kPa, or about 275 kPa to about 300 kPa, or about 300 kPa to about 414kPa, or from about 300 kPa to about 400 kPa, or from about 300 kPa to about 350 kPa, or about 350 kPa to about 414kPa, or from about 350 kPa to about 400 kPa, or about 400 kPa to about 414kPa..
[00103] The stream may be applied from a first distance from the external surface of about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, or about 25 cm to about 30 cm, or 8, 10, 15, 20, 25, or 30, and preferably 10 cm.
[00104] The stream is applied perpendicularly to the external surface of the carbon material.
[00105] Simultaneously to application of the stream of coating, a curtain of air is applied, at a velocity of about 35 m/s to about 55 m/s, or about 35 m/s to about 50 m/s, or about 35 m/s to about 45 m/s, or about 35 m/s to about 40 m/s, or about 40 m/s to about 55 m/s, or about 40 m/s to about
50 m/s, or about 40 m/s to about 45 m/s, or about 45 m/s to about 55 m/s, or about 45 m/s to about
50 m/s, or about 50 m/s to about 55 m/s, or about 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, and 55, preferably 42 m/s, also perpendicular to the external surface being coated.
[00106] The curtain of air is applied from a second distance from the external surface of about 10 mm to about 40 mm, or about 10 mm to about 35 mm, or about 10 mm to about 30 mm, or about
10 mm to about 25 mm, or about 10 mm to about 20 mm, or about 10 mm to about 15 mm, or about
12 mm to about 40 mm, or about 12 to about 35 mm, or about 12 mm to about 30 mm, or about 12 mm to about 25 mm, or about 12 mm to about 20 mm, or about 12 mm to about 15 mm, or 13 mm to about 40 mm, 13 about to about 35 mm, or about 13 mm to about 30 mm, or about 13 mm to about 25 mm, or about 13 mm to about 20 mm, or about 13 mm to about 15 mm, or 14 mm to about 40 mm, or about 14 mm to about 35 mm, or about 14 mm to about 30 mm, or about 14 mm to about 25 mm, or about 14 mm to about 20 mm, or about 14 mm to about 15 mm, or 16 mm to about 40 mm, or about 16 mm to about 35 mm, or about 16 mm to about 30 mm, or about 16 mm to about 25 mm, or about 16 mm to about 20 mm, or 18 mm to about 40 mm, or about 18 mm to about 35 mm, or about 18 mm to about 30 mm, or about 18 mm to about 25 mm, or 20 mm to about 40 mm, or about 20 mm to about 35 mm, or about 20 mm to about 30 mm, or 25 mm to about 40 mm, or about 25 mm to about 35 mm, or about 25 mm to about 30 mm, or 30 mm to about 40 mm, or about 30 mm to about 35 mm, or 35 mm to about 40 mm, or about 10, 15, 20, 25, 30, 35, or 40 mm, perpendicular to the external surface.
[00107] Application of the aqueous priming coating composition as a stream under pressure simultaneously with the air curtain provides an even distribution of the aqueous priming coating composition over the external surface. [00108] In embodiments, the stream of aqueous priming coating composition may comprise an application pattern of from about 8 cm to about 40 cm, or about 8 cm to about 35 cm, or about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, from about 10 cm to about 40 cm, or about 10 cm to about 35 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, from about 15 cm to about 40 cm, or about 15 cm to about 35 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, from about 20 cm to about 40 cm, or about 20 cm to about 35 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, from about 25 cm to about 40 cm, or about 25 cm to about 35 cm, or about 25 cm to about 30 cm, or from about 30 cm to about 40 cm, or about 30 cm to about 35 cm, or from about 35 cm to about 40 cm, or 8, 10, 15, 20, 25, 30, 35, or 40 cm.
[00109] In embodiments, applying the stream of aqueous priming coating composition may be performed at a flow rate of about 0.4 L/min to about 1 L/min, or about 0.4 L/min to about 0.9 L/min, or about 0.4 L/min to about 0.8 L/min, or about 0.4 L/min to about 0.7 L/min, or about 0.4 L/min to about 0.6L/min, or about 0.4 L/min to about 0.5 L/min, or about 0.5 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.5 L/min to about 0.8 L/min, or about 0.5 L/min to about 0.7 L/min, or about 0.5 L/min to about 0.6L/min, or about 0.6 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.6 L/min to about 0.8 L/min, or about 0.6 L/min to about 0.7 L/min, or about 0.7 L/min to about 1 L/min, or about 0.7 L/min to about 0.9 L/min, or about 0.7 L/min to about 0.8 L/min, or about 0.8 L/min to about 1 L/min, or about 0.8 L/min to about 0.9 L/min, or about 0.9 L/min to about 1 L/min, or about 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95. 1.0 L/min.
[00110] In embodiments, the stream of aqueous priming coating composition and the curtain of air are displaced perpendicular to the external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec, or from about 2 cm/sec to about 18 cm/sec, or from about 2 cm/sec to about 16 cm/sec, or from about 2 cm/sec to about 15 cm/sec, or from about 2 cm/sec to about 14 cm/sec, or from about 2 cm/sec to about 12 cm/sec, or from about 2 cm/sec to about 10 cm/sec, or from about 2 cm/sec to about 8 cm/sec, or from about 2 cm/sec to about 6 cm/sec, or from about 2 cm/sec to about 4 cm/sec, or about 4 cm/sec to about 20 cm/sec, or from about 4 cm/sec to about 18 cm/sec, or from about 4 cm/sec to about 16 cm/sec, or from about 4 cm/sec to about 15 cm/sec, or from about 4 cm/sec to about 14 cm/sec, or from about 4 cm/sec to about 12 cm/sec, or from about 4 cm/sec to about 10 cm/sec, or from about 4 cm/sec to about 8 cm/sec, or from about 4 cm/sec to about 6 cm/sec, or about 6 cm/sec to about 20 cm/sec, or from about 6 cm/sec to about 18 cm/sec, or from about 6 cm/sec to about 16 cm/sec, or from about 6 cm/sec to about 15 cm/sec, or from about 6 cm/sec to about 14 cm/sec, or from about 6 cm/sec to about 12 cm/sec, or from about 6 cm/sec to about 10 cm/sec, or from about 6 cm/sec to about 8 cm/sec, or about 8 cm/sec to about 20 cm/sec, or from about 8 cm/sec to about 18 cm/sec, or from about 8 cm/sec to about 16 cm/sec, or from about 8 cm/sec to about 15 cm/sec, or from about 8 cm/sec to about 14 cm/sec, or from about 8 cm/sec to about 12 cm/sec, or from about 8 cm/sec to about 10 cm/sec, or about 10 cm/sec to about 20 cm/sec, or from about 10 cm/sec to about 18 cm/sec, or from about 10 cm/sec to about 16 cm/sec, or from about 10 cm/sec to about 15 cm/sec, or from about 10 cm/sec to about 14 cm/sec, or from about 10 cm/sec to about 12 cm/sec, or about 12 cm/sec to about 20 cm/sec, or from about 12 cm/sec to about 18 cm/sec, or from about 12 cm/sec to about 16 cm/sec, or from about 12 cm/sec to about 15 cm/sec, or from about 12 cm/sec to about 14 cm/sec, or about 14 cm/sec to about 20 cm/sec, or from about 14 cm/sec to about 18 cm/sec, or from about 14 cm/sec to about 16 cm/sec, or from about 14 cm/sec to about 15 cm/sec, or about 15 cm/sec to about 20 cm/sec, or from about 15 cm/sec to about 18 cm/sec, or from about 15 cm/sec to about 16 cm/sec, or about 16 cm/sec to about 20 cm/sec, or from about 16 cm/sec to about 18 cm/sec, or about 18 cm/sec to about 20 cm/sec, or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15,16, 17, 18, 19, or 20 cm/sec.
[00111] According to another embodiment, a distance between a central axis of the stream of aqueous priming coating composition and a central axis of the curtain of air may be from about 100 mm to about 300 mm, or about 100 mm to about 250 mm, or about 100 mm to about 200 mm, or about 100 mm to about 150 mm, or about 100 mm to about 125 mm, or about 125 mm to about 300 mm, or about 125 mm to about 250 mm, or about 125 mm to about 200 mm, or about 125 mm to about 150 mm, or about 150 mm to about 300 mm, or about 150 mm to about 250 mm, or about 150 mm to about 200 mm, or about 200 mm to about 300 mm, or about 200 mm to about 250 mm, or about 250 mm to about 300 mm, or 100, 125, 150, 200, 250, or 300 mm.
Priming coating composition
[00112] As used herein, aqueous priming coating composition refers to an aqueous priming coating composition as disclosed in PCT/CA2018/051083 which is incorporated herein by reference, for application to a carbon material which comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide select from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water.
[00113] Carbon materials, such as carbon anodes, are not wetted by molten salts. The aqueous coating of the present invention is preferably applied on an intermediate substrate, such as a priming coating composition described herein. The priming coating composition of the present invention is a formulation of water-based coating (designated aqueous priming coating composition) that highly adheres mechanically on carbon materials, such as anodes, by filling their surface defects, such as open pores and microcracks or microfissures. This coating is preferably containing up to 94 to 96% w/w alumina - aluminum oxide - (on a dry basis). Colloidal binders may be included to act as substrate for the aqueous coating composition. During the application of the aqueous coating composition on the aqueous priming coating, the dissolved salts of sodium and potassium carbonate contained into the aqueous coating composition penetrate the open pores of the aqueous priming coating while most of the lithium salt of carbonate (e.g. U2CO3) from the aqueous coating composition is accumulated on the aqueous priming coating surface. Due to the much lower solubility of the NaHCC>3 and KHCO3 salts compared to Na2CC>3 and K2CO3, respectively, a lesser degree of penetration into the aqueous priming coating is obtained with the alternative aqueous coating composition whose adherence is consequently lower, as it has been observed that it is easier to dislodge a coating made with bicarbonates.
[00114] In embodiments, the concentration of the calcined aluminum oxide may be from about 32% to 41% w/w, or from about 32% to 40% w/w, or from about 32% to 39% w/w, or from about 32% to 38% w/w, or from about 32% to 37% w/w, or from about 32% to 36% w/w, or from about 32% to 35% w/w, or from about 32% to 34% w/w, or from about 32% to 33% w/w, or from about 33% to 41% w/w, or from about 33% to 40% w/w, or from about 33% to 39% w/w, or from about 33% to 38% w/w, or from about 33% to 37% w/w, or from about 33% to 36% w/w, or from about 33% to 35% w/w, or from about 33% to 34% w/w, or from about 34% to 41% w/w, or from about 34% to 40% w/w, or from about 34% to 39% w/w, or from about 34% to 38% w/w, or from about 34% to 37% w/w, or from about 34% to 36% w/w, or from about 34% to 35% w/w, or from about 35% to 41% w/w, or from about 35% to 40% w/w, or from about 35% to 39% w/w, or from about 35% to 38% w/w, or from about 35% to 37% w/w, or from about 35% to 36% w/w, or from about 36% to 41% w/w, or from about 36% to 40% w/w, or from about 36% to 39% w/w, or from about 36% to 38% w/w, or from about 36% to 37% w/w, or from about 37% to 41% w/w, or from about 37% to 40% w/w, or from about 37% to 39% w/w, or from about 37% to 38% w/w, or from about 38% to 41% w/w, or from about 38% to 40% w/w, or from about 38% to 39% w/w, or from about 39% to 41% w/w, or from about 39% to 40% w/w, or is from about 35.29% to 38.07% w/w or from about 40% to 41% w/w, or about 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 35.29% or 38.07% w/w of the aqueous priming coating composition.
[00115] In embodiments, the concentration of reactive aluminum oxide may be from about 6% to 9% w/w, or from about 6% to 8% w/w, or from about 6% to 7% w/w, or from about 7% to 9% w/w, or from about 7% to 8% w/w, or from about 8% to 9% w/w, or from about 7.41 % to 7.99% w/w or 6%, 7%, 8%, 9%, or 7.41% or 7.99% w/w of the aqueous priming coating composition. [00116] In embodiments, the concentration of white fused aluminum oxide may be from about
31 % to 40% w/w, or from about 31 % to 39% w/w, or from about 31 % to 38% w/w, or from about 31 % to 37% w/w, or from about 31% to 36% w/w, or from about 31% to 35% w/w, or from about 31% to 34% w/w, or from about 31% to 33% w/w, or from about 31% to 32% w/w, or from about 32% to 40% w/w, or from about 32% to 39% w/w, or from about 32% to 38% w/w, or from about 32% to 37% w/w, or from about 32% to 36% w/w, or from about 32% to 35% w/w, or from about 32% to 34% w/w, or from about 32% to 33% w/w, or from about 33% to 40% w/w, or from about 33% to 39% w/w, or from about 33% to 38% w/w, or from about 33% to 37% w/w, or from about 33% to 36% w/w, or from about 33% to 35% w/w, or from about 33% to 34% w/w, or from about 34% to 40% w/w, or from about 34% to 39% w/w, or from about 34% to 38% w/w, or from about 34% to 37% w/w, or from about 34% to 36% w/w, or from about 34% to 35% w/w, or from about 35% to 40% w/w, or from about 35% to 39% w/w, or from about 35% to 38% w/w, or from about 35% to 37% w/w, or from about 35% to 36% w/w, or from about 36% to 40% w/w, or from about 36% to 39% w/w, or from about 36% to 38% w/w, or from about 36% to 37% w/w, or from about 37% to 40% w/w, or from about 37% to 39% w/w, or from about 37% to 38% w/w, or from about 38% to 40% w/w, or from about 38% to 39% w/w, or from about 39% to 40% w/w, or is from about 34.13% to 36.81% w/w, or about 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 34.13% or 36.81% w/w of the aqueous priming coating composition.
[00117] In embodiments, the white fused aluminum oxide may have particle size of up to about 0.2 mm and less (i.e., passing across the No. 70 ASTM Tyler Mesh screen).
[00118] In embodiments, the aqueous priming coating composition may further comprise a calcium salt of carbonate, and the calcium salt of carbonate may be selected from the group consisting of calcium carbonate (CaCC>3), calcium bicarbonate [Ca(HCC>3)2], and combinations thereof.
[00119] In embodiments, the concentration of the calcium carbonate may be up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 5%, or about 0.5%, 1%, 2%, 3%, 4%, 5%, or 3.8% w/w of the aqueous priming coating composition. [00120] In embodiments, the aqueous priming coating composition may further comprise a liquid binder. The liquid binder may comprise colloidal silica, colloidal alumina, a deflocculant and combinations thereof.
[00121] In embodiments, the concentration of the colloidal silica may be up to 12% w/w, or up to 11 % w/w, or up to 10% w/w, or up to 9% w/w, or up to 8% w/w, or up to 7% w/w, or up to 6% w/w, or up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 12%, or from about 0.5% to about 11%, or from about 0.5% to about 10%, or from about 0.5% to about 9%, or from about 0.5% to about 8%, or from about 0.5% to about 7%, or from about 0.5% to about 6%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 12%, or from about 1% to about 11%, or from about 1% to about 10%, or from about 1% to about 9%, or from about 1% to about 8%, or from about 1% to about 7%, or from about 1 % to about 6%, or from about 1 % to about 5%, or from about 1 % to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 12%, or from about 2% to about 11%, or from about 2% to about 10%, or from about 2% to about 9%, or from about 2% to about 8%, or from about 2% to about 7%, or from about 2% to about 6%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 12%, or from about 3% to about 11%, or from about 3% to about 10%, or from about 3% to about 9%, or from about 3% to about 8%, or from about 3% to about 7%, or from about 3% to about 6%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 12%, or from about 4% to about 11%, or from about 4% to about 10%, or from about 4% to about 9%, or from about 4% to about 8%, or from about 4% to about 7%, or from about 4% to about 6%, or from about 4% to about 5%, or from about 5% to about 12%, or from about 5% to about 11%, or from about 5% to about 10%, or from about 5% to about 9%, or from about 5% to about 8%, or from about 5% to about 7%, or from about 5% to about 6%, or from about 6% to about 12%, or from about 6% to about 11%, or from about 6% to about 10%, or from about 6% to about 9%, or from about 6% to about 8%, or from about 6% to about 7%, or from about 7% to about 12%, or from about 7% to about 11%, or from about 7% to about 10%, or from about 7% to about 9%, or from about 7% to about 8%, or from about 8% to about 12%, or from about 8% to about 11%, or from about 8% to about 10%, or from about 8% to about 9%, or from about 9% to about 12%, or from about 9% to about 11%, or from about 9% to about 10%, or from about 10% to about 12%, or from about 10% to about 11%, or from about 11% to about 12%, or from about 1.22% to about 9.49% w/w, or about 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, or 1.22%, or 9.49% w/w of the aqueous priming coating composition. [00122] In embodiments, the concentration of the colloidal alumina may be up to 14% w/w, or up to 13% w/w, or up to 12% w/w, or up to 11% w/w, or up to 10% w/w, or up to 9% w/w, or up to 8% w/w, or up to 7% w/w, or up to 6% w/w, or up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 14%, or from about 0.5% to about 13%, or from about 0.5% to about 12%, or from about 0.5% to about 11%, or from about 0.5% to about 10%, or from about 0.5% to about 9%, or from about 0.5% to about 8%, or from about 0.5% to about 7%, or from about 0.5% to about 6%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 14%, or from about 1% to about 13%, or from about 1% to about 12%, or from about 1% to about 11%, or from about 1% to about 10%, or from about 1% to about 9%, or from about 1% to about 8%, or from about 1% to about 7%, or from about 1% to about 6%, or from about 1 % to about 5%, or from about 1 % to about 4%, or from about 1 % to about 3%, or from about 1% to about 2%, or from about 2% to about 14%, or from about 2% to about 13%, or from about 2% to about 12%, or from about 2% to about 11%, or from about 2% to about 10%, or from about 2% to about 9%, or from about 2% to about 8%, or from about 2% to about 7%, or from about 2% to about 6%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 14%, or from about 3% to about 13%, or from about 3% to about 12%, or from about 3% to about 11%, or from about 3% to about 10%, or from about 3% to about 9%, or from about 3% to about 8%, or from about 3% to about 7%, or from about 3% to about 6%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 14%, or from about 4% to about 13%, or from about 4% to about 12%, or from about 4% to about 11%, or from about 4% to about 10%, or from about 4% to about 9%, or from about 4% to about 8%, or from about 4% to about 7%, or from about 4% to about 6%, or from about 4% to about 5%, or from about 5% to about 14%, or from about 5% to about 13%, or from about 5% to about 12%, or from about 5% to about 11%, or from about 5% to about 10%, or from about 5% to about 9%, or from about 5% to about 8%, or from about 5% to about 7%, or from about 5% to about 6%, or from about 6% to about 14%, or from about 6% to about 13%, or from about 6% to about 12%, or from about 6% to about 11%, or from about 6% to about 10%, or from about 6% to about 9%, or from about 6% to about 8%, or from about 6% to about 7%, or from about 7% to about 14%, or from about 7% to about 13%, or from about 7% to about 12%, or from about 7% to about 11%, or from about 7% to about 10%, or from about 7% to about 9%, or from about 7% to about 8%, or from about 8% to about 14%, or from about 8% to about 13%, or from about 8% to about 12%, or from about 8% to about 11%, or from about 8% to about 10%, or from about 8% to about 9%, or from about 9% to about 14%, or from about 9% to about 13%, or from about 9% to about 12%, or from about 9% to about 11%, or from about 9% to about 10%, or from about 10% to about 14%, or from about 10% to about 13%, or from about 10% to about 12%, or from about 10% to about 11%, or from about 11% to about 14%, or from about 11% to about 13%, or from about 11% to about 12%, or from about 12% to about 14%, or from about 12% to about 13%, or from about 13% to about 14%, or about 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 10.36% w/w of the aqueous priming coating composition.
[00123] In embodiments, the liquid binder may also comprise a deflocculant, which is a compound that is added to the composition to minimize settling out, prevent flocculation and disperse the other ingredients, increase fluidity of the composition, and help form a colloid or suspension. The deflocculant may be selected from the group consisting of polyethylene glycol graft polymers such as castament® FS10, FS20 or FS60.
[00124] In embodiments, the deflocculant may be from about 6% to about 10% w/w, or from about 6% to about 9% w/w, or from about 6% to about 8% w/w, or from about 6% to about 7% w/w, or from about 7% to about 10% w/w, or from about 7% to about 9% w/w, or from about 7% to about 8% w/w, or from about 8% to about 10% w/w, or from about 8% to about 9% w/w, or from about 9% to about 10% w/w, or about 7.42% to about 7.64% w/w, or about 6%, 7%, 8%, 9%, 10%, or 7.42%, or 7.64% w/w of the aqueous priming coating composition.
[00125] In embodiments, the layer of the aqueous priming coating composition on the external surface may have a wet film thickness of about 0.100 mm to about 0.150 mm. In embodiments, multiple applications of the aqueous priming coating composition are made. Indeed, according to some embodiments, a second or more layer of the aqueous priming coating composition may be applied by the method of the present invention, by conventional spray coating, or a combination thereof.
[00126] In embodiments, the aqueous priming coating composition may be dried at room temperature for about 2 minutes or more, prior to application of a subsequent aqueous priming coating composition layer.
[00127] According to some embodiments, when applying the aqueous priming coating composition to the external surface, the external surface may have a surface temperature of about 5°C to about 50°C. According to another embodiment, the aqueous priming coating composition may applied at a temperature of about 5°C to about 50°C.
[00128] According to another embodiment, the method of the present invention may further comprise applying an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
Aqueous coating composition
[00129] As used herein, aqueous carbonate coating composition or carbonate composition or aqueous coating composition refers to an aqueous coating composition as disclosed in PCT/CA2018/051083 which is incorporated herein by reference, for preventing or reducing air oxidation of a carbon material (for example graphite, petroleum or metallurgical coke or any other partially graphitized carbon, amorphous carbon) comprising an aqueous solution comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate, and water, the aqueous coating having a melting temperature of from about 600°C.
[00130] In an embodiment the aqueous coating composition for preventing or reducing air oxidation of a carbon material comprises an aqueous solution comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate, a lithium salt, and water, the aqueous coating having a melting temperature of from about 370°C to about 430°C. To the salts of sodium and potassium carbonate, an equivalent LhO molar content varying between about 17% and 74% of the composition is added. The equivalent U2O molar content is to be provided by lithium carbonate (U2CO3), lithium bicarbonate (UHCO3), LiF, a mixture of LiF and NaF, or a combination or all of the above, to reach a theoretical melting temperature of 370°C to 430°C, and preferably 400°C, although they have a very low solubility in water. Among U2CO3, LiF and NaF, the former has the lowest density (2.11 , versus 2.64 and 2.56 g/cm3, respectively). Among these salts, U2CO3 leads to the lowest sedimentation rate into concentrated aqueous solutions of Na2CC>3 and K2CO3.
[00131] An embodiment of the present invention concerns the formulation of a water coating which may be made from a mixture sodium salts of carbonate, potassium salts of carbonate. The sodium salt of carbonate and a potassium salt of carbonate are mixed in quantities that provide an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, to provide an aqueous coating having a melting temperature of up to 600°C.
[00132] The equivalent molar ratio for sodium and potassium salts of carbonate may be derived according to the following:
Figure imgf000021_0001
[00133] In embodiments, the equivalent Na20:K20 molar ratio is from about 0.4 to about 2.0, or about 0.4 to about 1.9, or about 0.4 to about 1 .8, or about 0.4 to about 1 .7, or about 0.4 to about
1 .6, or about 0.4 to about 1.5, or about 0.4 to about 1.4, or about 0.4 to about 1.3, or about 0.4 to about 1.2, or about 0.4 to about 1.1 , or about 0.4 to about 1.0, or about 0.4 to about 0.9, or about 0.4 to about 0.8, or about 0.4 to about 0.7, or about 0.4 to about 0.6, or about 0.4 to about 0.5, or about 0.5 to about 2.0, or about 0.5 to about 1.9, or about 0.5 to about 1.8, or about 0.5 to about 1.7, or about 0.5 to about 1.6, or about 0.5 to about 1.5, or about 0.5 to about 1.4, or about 0.5 to about 1 .3, or about 0.5 to about 1.2, or about 0.5 to about 1.1 , or about 0.5 to about 1 .0, or about 0.5 to about 0.9, or about 0.5 to about 0.8, or about 0.5 to about 0.7, or about 0.5 to about 0.6, or from about 0.6 to about 2.0, or about 0.6 to about 1.9, or about 0.6 to about 1 .8, or about 0.6 to about 1 .7, or about 0.6 to about 1.6, or about 0.6 to about 1.5, or about 0.6 to about 1.4, or about 0.6 to about 1 .3, or about 0.6 to about 1.2, or about 0.6 to about 1.1 , or about 0.6 to about 1.0, or about 0.6 to about 0.9, or about 0.6 to about 0.8, or about 0.6 to about 0.7, or from about 0.7 to about 2.0, or about 0.7 to about 1.9, or about 0.7 to about 1 .8, or about 0.7 to about 1.7, or about 0.7 to about 1 .6, or about 0.7 to about 1 .5, or about 0.7 to about 1.4, or about 0.7 to about 1 .3, or about 0.7 to about 1 .2, or about 0.7 to about 1.1 , or about 0.7 to about 1.0, or about 0.7 to about 0.9, or about 0.7 to about 0.8, or from about 0.7 to about 2.0, or about 0.7 to about 1.9, or about 0.7 to about 1.8, or about 0.7 to about
1 .7, or about 0.7 to about 1.6, or about 0.7 to about 1.5, or about 0.7 to about 1.4, or about 0.7 to about 1.3, or about 0.7 to about 1 .2, or about 0.7 to about 1.1 , or about 0.7 to about 1 .0, or about 0.7 to about 0.9, or from about 0.7 to about 2.0, or about 0.7 to about 1.9, or about 0.7 to about 1.8, or about 0.7 to about 1.7, or about 0.7 to about 1.6, or about 0.7 to about 1.5, or about 0.7 to about 1 .4, or about 0.7 to about 1.3, or about 0.7 to about 1 .2, or about 0.7 to about 1.1 , or about 0.7 to about 1 .0, or about 0.7 to about 0.9, or from about 0.7 to about 2.0, or about 0.7 to about 1 .9, or about 0.7 to about 1 .8, or about 0.7 to about 1.7, or about 0.7 to about 1 .6, or about 0.7 to about 1 .5, or about 0.7 to about 1.4, or about 0.7 to about 1.3, or about 0.7 to about 1.2, or about 0.7 to about 1.1 , or about 0.7 to about 1.0, or about 0.7 to about 0.9, or from about 0.8 to about 2.0, or about 0.8 to about 1.9, or about 0.8 to about 1.8, or about 0.8 to about 1.7, or about 0.8 to about 1.6, or about 0.8 to about 1.5, or about 0.8 to about 1 .4, or about 0.8 to about 1.3, or about 0.8 to about 1.2, or about 0.8 to about 1.1 , or about 0.8 to about 1 .0, or about 0.8 to about 0.9, or from about 0.9 to about 2.0, or about 0.9 to about 1.9, or about 0.9 to about 1.8, or about 0.9 to about 1.7, or about 0.9 to about 1 .6, or about 0.9 to about 1.5, or about 0.9 to about 1 .4, or about 0.9 to about 1 .3, or about 0.9 to about 1 .2, or about 0.9 to about 1.1 , or about 0.9 to about 1 .0, or from about 1.0 to about 2.0, or about 1.0 to about 1 .9, or about 1.0 to about 1 .8, or about 1.0 to about 1 .7, or about 1.0 to about 1 .6, or about 1 .0 to about 1.5, or about 1.0 to about 1.4, or about 1.0 to about 1 .3, or about 1.0 to about 1.2, or about 1.0 to about 1.1 , or from about 1.1 to about 2.0, or about 1.1 to about 1.9, or about 1.1 to about 1 .8, or about 1.1 to about 1.7, or about 1.1 to about 1.6, or about 1.1 to about 1.5, or about 1.1 to about 1.4, or about 1.1 to about 1.3, or about 1.1 to about 1.2, or from about 1.2 to about 2.0, or about 1.2 to about 1.9, or about 1.2 to about 1.8, or about 1.2 to about 1.7, or about 1.2 to about 1 .6, or about 1.2 to about 1.5, or about 1.2 to about 1 .4, or about 1 .2 to about 1.3, or from about 1 .3 to about 2.0, or about 1.3 to about 1 .9, or about 1.3 to about 1.8, or about 1.3 to about 1 .7, or about 1 .3 to about 1 .6, or about 1.3 to about 1.5, or about 1.3 to about 1 .4, or from about 1 .4 to about 2.0, or about 1.4 to about 1.9, or about 1.4 to about 1.8, or about 1.4 to about 1.7, or about 1.4 to about 1 .6, or about 1.4 to about 1 .5, or from about 1.5 to about 2.0, or about 1 .5 to about 1.9, or about 1 .5 to about 1.8, or about 1.5 to about 1.7, or about 1.5 to about 1.6, or from about 1.6 to about 2.0, or about 1 .6 to about 1.9, or about 1.6 to about 1 .8, or about 1.6 to about 1 .7, or from about 1 .7 to about 2.0, or about 1.7 to about 1.9, or about 1.7 to about 1.8, or from about 1 .8 to about 2.0, or about 1.8 to about 1.9, or from about 1.9 to about 2.0, or about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0. Such aqueous coatings comprising the sodium salts and potassium salts of carbonate, such as Na2CC>3, K2CO3, and in the indicated equivalent molar ratio display melting temperatures that may be up to 600°C, such that they can prevent and/or reduce air oxidation from that temperature and above.
[00134] According to another embodiment, this invention concerns the formulation of a water coating which may be made from a mixture sodium salts of carbonate, potassium salts of carbonate, and lithium salts. The sodium salt of carbonate and a potassium salt of carbonate are mixed in quantities that provide an equivalent Na20:K20 molar ratio of about 0.4 to about 1.8, to provide an aqueous coating having a melting temperature of between about 370°C and 430°C, and preferably about 400°C. In these embodiments, the combination of the sodium salt of carbonate and the potassium salt of carbonate provide an equivalent Na20:K20 molar ratio varying between about 0.4 to about 1.8, or from about 0.4 to about 1.7, or from about 0.4 to about 1.6, or from about 0.4 to about 1 .5, or from about 0.4 to about 1 .4, or from about 0.4 to about 1 .3, or from about 0.4 to about 1 .2, or from about 0.4 to about 1 .0, or from about 0.4 to about 0.9, or from about 0.4 to about 0.8, or from about 0.4 to about 0.7, or from about 0.4 to about 0.6, or from about 0.4 to about 0.5, or from about 0.5 to about 1 .8, or from about 0.5 to about 1.7, or from about 0.5 to about 1 .6, or from about 0.5 to about 1.5, or from about 0.5 to about 1.4, or from about 0.5 to about 1.3, or from about 0.5 to about 1 .2, or from about 0.5 to about 1 .0, or from about 0.5 to about 0.9, or from about 0.5 to about 0.8, or from about 0.5 to about 0.7, or from about 0.5 to about 0.6, or from about 0.6 to about 1 .8, or from about 0.6 to about 1.7, or from about 0.6 to about 1.6, or from about 0.6 to about 1.5, or from about 0.6 to about 1 .4, or from about 0.6 to about 1.3, or from about 0.6 to about 1 .2, or from about 0.6 to about 1.0, or from about 0.6 to about 0.9, or from about 0.6 to about 0.8, or from about 0.6 to about 0.7, or from about 0.7 to about 1 .8, or from about 0.7 to about 1.7, or from about 0.7 to about 1 .6, or from about 0.7 to about 1 .5, or from about 0.7 to about 1.4, or from about 0.7 to about 1 .3, or from about 0.7 to about 1.2, or from about 0.7 to about 1.0, or from about 0.7 to about 0.9, or from about 0.7 to about 0.8, or from about 0.8 to about 1.8, or from about 0.8 to about 1 .7, or from about 0.8 to about 1.6, or from about 0.8 to about 1.5, or from about 0.8 to about 1.4, or from about 0.8 to about 1 .3, or from about 0.8 to about 1 .2, or from about 0.8 to about 1.0, or from about 0.8 to about 0.9, or from about 0.9 to about 1 .8, or from about 0.9 to about 1.7, or from about 0.9 to about 1 .6, or from about 0.9 to about 1.5, or from about 0.9 to about 1.4, or from about 0.9 to about 1.3, or from about 0.9 to about 1 .2, or from about 0.9 to about 1.0, or from about 1 .0 to about 1 .8, or from about 1 .0 to about 1.7, or from about 1.0 to about 1.6, or from about 1 .0 to about 1.5, or from about 1.0 to about 1 .4, or from about 1.0 to about 1 .3, or from about 1.0 to about 1.2, or from about 1.1 to about 1.8, or from about 1.1 to about 1.7, or from about 1.1 to about 1.6, or from about 1.1 to about 1.5, or from about 1.1 to about 1.4, or from about 1.1 to about 1.3, or from about 1.2 to about 1.8, or from about 1 .2 to about 1 .7, or from about 1.2 to about 1.6, or from about 1 .2 to about 1 .5, or from about 1 .2 to about 1 .4, or from about 1. 2 to about 1 .3, or from about 1.3 to about 1.8, or from about 1 .3 to about 1 .7, or from about 1.3 to about 1 .6, or from about 1.3 to about 1.5, or from about 1.3 to about 1 .4, or from about 1.4 to about 1 .8, or from about 1.4 to about 1.7, or from about 1 .4 to about 1 .6, or from about 1.4 to about 1.5, or from about 1.5 to about 1.8, or from about 1.5 to about 1.7, or from about 1 .5 to about 1 .6, or from about 1.6 to about 1.8, or from about 1 .6 to about 1 .7, or from about 1.7 to about 1.8, or about 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, and 1.8. Such aqueous coatings comprising the sodium salts and potassium salts of carbonate, such as Na2CC>3, K2CO3, in the indicated equivalent molar ratio, and the lithium salt, such as U2CO3, display melting temperatures that may be between about 370°C and 430°C, and preferably about 400°C, such that they can prevent and/or reduce air oxidation from that temperature and above.
[00135] Therefore, in embodiments of the present invention, the sodium salt of carbonate may be selected from the group consisting of sodium carbonate (Na2CC>3), and sodium bicarbonate (NaHCC>3), and combinations thereof. The potassium salt of carbonate may be selected from the group consisting of potassium carbonate (K2CO3), and potassium bicarbonate (KHCO3), and combinations thereof. In preferred embodiments, the combination of a sodium salt of carbonate and a potassium salt of carbonate is a combination of sodium carbonate and potassium carbonate. In another preferred embodiments, the combination of a sodium salt of carbonate and a potassium salt of carbonate is a combination of sodium bicarbonate and potassium bicarbonate.
[00136] According to some embodiments, the concentration of sodium carbonate may be from about 7% to about 17% w/w, or from about 7% to about 16% w/w, or from about 7% to about 15% w/w, or from about 7% to about 14% w/w, or from about 7% to about 13% w/w, or from about 7% to about 12% w/w, or from about 7% to about 11% w/w, or from about 7% to about 10% w/w, or from about 7% to about 9% w/w, or from about 7% to about 8% w/w, or 8% to about 17% w/w, or from about 8% to about 16% w/w, or from about 8% to about 15% w/w, or from about 8% to about 14% w/w, or from about 8% to about 13% w/w, or from about 8% to about 12% w/w, or from about 8% to about 11% w/w, or from about 8% to about 10% w/w, or from about 8% to about 9% w/w, or 9% to about 17% w/w, or from about 9% to about 16% w/w, or from about 9% to about 15% w/w, or from about 9% to about 14% w/w, or from about 9% to about 13% w/w, or from about 9% to about 12% w/w, or from about 9% to about 11% w/w, or from about 9% to about 10% w/w, or 10% to about 17% w/w, or from about 10% to about 16% w/w, or from about 10% to about 15% w/w, or from about
10% to about 14% w/w, or from about 10% to about 13% w/w, or from about 10% to about 12% w/w, or from about 10% to about 11% w/w, or 11% to about 17% w/w, or from about 11% to about 16% w/w, or from about 11% to about 15% w/w, or from about 11% to about 14% w/w, or from about 11% to about 13% w/w, or from about 11% to about 12% w/w, or 12% to about 17% w/w, or from about
12% to about 16% w/w, or from about 12% to about 15% w/w, or from about 12% to about 14% w/w, or from about 12% to about 13% w/w, or 13% to about 17% w/w, or from about 13% to about 16% w/w, or from about 13% to about 15% w/w, or from about 13% to about 14% w/w, or 14% to about
17% w/w, or from about 14% to about 16% w/w, or from about 14% to about 15% w/w, or 15% to about 17% w/w, or from about 15% to about 16% w/w, or 16% to about 17% w/w, or about 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or about 12.75%, or about 13.59% w/w of the aqueous coating composition.
[00137] According to another embodiment, the concentration of sodium bicarbonate may be from about 11% to about 31% w/w, or from about 11% to about 30% w/w, or from about 11% to about 29% w/w, or from about 11% to about 28% w/w, or from about 11% to about 27% w/w, or from about 11% to about 26% w/w, or from about 11% to about 25% w/w, or from about 11% to about 24% w/w, or from about 11% to about 23% w/w, or from about 11% to about 22% w/w, or from about 11% to about 21% w/w, or from about 11% to about 20% w/w, or from about 11% to about 19% w/w, or from about 11% to about 18% w/w, or from about 11% to about 17% w/w, or from about 11% to about 16% w/w, or from about 11% to about 15% w/w, or from about 11% to about 14% w/w, or from about 11% to about 13% w/w, or from about 11% to about 12% w/w, or from about 12% to about 31% w/w, or from about 12% to about 30% w/w, or from about 12% to about 29% w/w, or from about 12% to about 28% w/w, or from about 12% to about 27% w/w, or from about 12% to about 26% w/w, or from about 12% to about 25% w/w, or from about 12% to about 24% w/w, or from about 12% to about 23% w/w, or from about 12% to about 22% w/w, or from about 12% to about 21% w/w, or from about 12% to about 20% w/w, or from about 12% to about 19% w/w, or from about 12% to about 18% w/w, or from about 12% to about 17% w/w, or from about 12% to about 16% w/w, or from about 12% to about 15% w/w, or from about 12% to about 14% w/w, or from about 12% to about 13% w/w, or from about 13% to about 31% w/w, or from about 13% to about 30% w/w, or from about 13% to about 29% w/w, or from about 13% to about 28% w/w, or from about 13% to about 27% w/w, or from about 13% to about 26% w/w, or from about 13% to about 25% w/w, or from about 13% to about 24% w/w, or from about 13% to about 23% w/w, or from about 13% to about 22% w/w, or from about 13% to about 21% w/w, or from about 13% to about 20% w/w, or from about 13% to about 19% w/w, or from about 13% to about 18% w/w, or from about 13% to about 17% w/w, or from about 13% to about 16% w/w, or from about 13% to about 15% w/w, or from about 13% to about 14% w/w, or from about 14% to about 31% w/w, or from about 14% to about 30% w/w, or from about 14% to about 29% w/w, or from about 14% to about 28% w/w, or from about 14% to about 27% w/w, or from about 14% to about 26% w/w, or from about 14% to about 25% w/w, or from about 14% to about 24% w/w, or from about 14% to about 23% w/w, or from about 14% to about 22% w/w, or from about 14% to about 21% w/w, or from about 14% to about 20% w/w, or from about 14% to about 19% w/w, or from about 14% to about 18% w/w, or from about 14% to about 17% w/w, or from about 14% to about 16% w/w, or from about 14% to about 15% w/w, or from about 15% to about 31% w/w, or from about 15% to about 30% w/w, or from about 15% to about 29% w/w, or from about 15% to about 28% w/w, or from about 15% to about 27% w/w, or from about 15% to about 26% w/w, or from about 15% to about 25% w/w, or from about 15% to about 24% w/w, or from about 15% to about 23% w/w, or from about 15% to about 22% w/w, or from about 15% to about 21% w/w, or from about 15% to about 20% w/w, or from about 15% to about 19% w/w, or from about 15% to about 18% w/w, or from about 15% to about 17% w/w, or from about 15% to about 16% w/w, or from about 16% to about 31% w/w, or from about 16% to about 30% w/w, or from about 16% to about 29% w/w, or from about 16% to about 28% w/w, or from about 16% to about 27% w/w, or from about 16% to about 26% w/w, or from about 16% to about 25% w/w, or from about 16% to about 24% w/w, or from about 16% to about 23% w/w, or from about 16% to about 22% w/w, or from about 16% to about 21% w/w, or from about 16% to about 20% w/w, or from about 16% to about 19% w/w, or from about 16% to about 18% w/w, or from about 16% to about 17% w/w, or from about 17% to about 31% w/w, or from about 17% to about 30% w/w, or from about 17% to about 29% w/w, or from about 17% to about 28% w/w, or from about 17% to about 27% w/w, or from about 17% to about 26% w/w, or from about 17% to about 25% w/w, or from about 17% to about 24% w/w, or from about 17% to about 23% w/w, or from about 17% to about 22% w/w, or from about 17% to about 21% w/w, or from about 17% to about 20% w/w, or from about 17% to about 19% w/w, or from about 17% to about 18% w/w, or from about 18% to about 31% w/w, or from about 18% to about 30% w/w, or from about 18% to about 29% w/w, or from about 18% to about 28% w/w, or from about 18% to about 27% w/w, or from about 18% to about 26% w/w, or from about 18% to about 25% w/w, or from about 18% to about 24% w/w, or from about 18% to about 23% w/w, or from about 18% to about 22% w/w, or from about 18% to about 21% w/w, or from about 18% to about 20% w/w, or from about 18% to about 19% w/w, or from about 19% to about 31% w/w, or from about 19% to about 30% w/w, or from about 19% to about 29% w/w, or from about 19% to about 28% w/w, or from about 19% to about 27% w/w, or from about 19% to about 26% w/w, or from about 19% to about 25% w/w, or from about 19% to about 24% w/w, or from about 19% to about 23% w/w, or from about 19% to about 22% w/w, or from about 19% to about 21% w/w, or from about 19% to about 20% w/w, or from about 20% to about 31% w/w, or from about 20% to about 30% w/w, or from about 20% to about 29% w/w, or from about 20% to about 28% w/w, or from about 20% to about 27% w/w, or from about 20% to about 26% w/w, or from about 20% to about 25% w/w, or from about 20% to about 24% w/w, or from about 20% to about 23% w/w, or from about 20% to about 22% w/w, or from about 20% to about 21% w/w, or from about 21% to about 31% w/w, or from about 21% to about 30% w/w, or from about 21% to about 29% w/w, or from about 21% to about 28% w/w, or from about 21% to about 27% w/w, or from about 21% to about 26% w/w, or from about 21% to about 25% w/w, or from about 21% to about 24% w/w, or from about 21% to about 23% w/w, or from about 21% to about 22% w/w, or from about 22% to about 31% w/w, or from about 22% to about 30% w/w, or from about 22% to about 29% w/w, or from about 22% to about 28% w/w, or from about 22% to about 27% w/w, or from about 22% to about 26% w/w, or from about 22% to about 25% w/w, or from about 22% to about 24% w/w, or from about 22% to about 23% w/w, or from about 23% to about 31% w/w, or from about 23% to about 30% w/w, or from about 23% to about 29% w/w, or from about 23% to about 28% w/w, or from about 23% to about 27% w/w, or from about 23% to about 26% w/w, or from about 23% to about 25% w/w, or from about 23% to about 24% w/w, or from about 24% to about 31% w/w, or from about 24% to about 30% w/w, or from about 24% to about 29% w/w, or from about 24% to about 28% w/w, or from about 24% to about 27% w/w, or from about 24% to about 26% w/w, or from about 24% to about 25% w/w, or from about 25% to about 31% w/w, or from about 25% to about 30% w/w, or from about 25% to about 29% w/w, or from about 25% to about 28% w/w, or from about 25% to about 27% w/w, or from about 25% to about 26% w/w, or from about 26% to about 31% w/w, or from about 26% to about 30% w/w, or from about 26% to about 29% w/w, or from about 26% to about 28% w/w, or from about 26% to about 27% w/w, or from about 27% to about 31% w/w, or from about 27% to about 30% w/w, or from about 27% to about 29% w/w, or from about 27% to about 28% w/w, or from about 28% to about 31% w/w, or from about 28% to about 30% w/w, or from about 28% to about 29% w/w, or from about 29% to about 31% w/w, or from about 29% to about 30% w/w, or from about 30% to about 31% w/w, or about 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, or about 21.68% w/w, of the aqueous coating composition.
[00138] According to another embodiment, the concentration of potassium carbonate may be from about 15% to about 25% w/w, or from about 15% to about 24% w/w, or from about 15% to about 23% w/w, or from about 15% to about 22% w/w, or from about 15% to about 21% w/w, or from about 15% to about 20% w/w, or from about 15% to about 19% w/w, or from about 15% to about 18% w/w, or from about 15% to about 17% w/w, or from about 15% to about 16% w/w, or from about 16% to about 25% w/w, or from about 16% to about 24% w/w, or from about 16% to about 23% w/w, or from about 16% to about 22% w/w, or from about 16% to about 21% w/w, or from about 16% to about 20% w/w, or from about 16% to about 19% w/w, or from about 16% to about 18% w/w, or from about 16% to about 17% w/w, or from about 17% to about 25% w/w, or from about 17% to about 24% w/w, or from about 17% to about 23% w/w, or from about 17% to about 22% w/w, or from about 17% to about 21% w/w, or from about 17% to about 20% w/w, or from about 17% to about 19% w/w, or from about 17% to about 18% w/w, or from about 18% to about 25% w/w, or from about 18% to about 24% w/w, or from about 18% to about 23% w/w, or from about 18% to about 22% w/w, or from about 18% to about 21% w/w, or from about 18% to about 20% w/w, or from about 18% to about 19% w/w, or from about 19% to about 25% w/w, or from about 19% to about 24% w/w, or from about 19% to about 23% w/w, or from about 19% to about 22% w/w, or from about 19% to about 21% w/w, or from about 19% to about 20% w/w, or from about 20% to about 25% w/w, or from about 20% to about 24% w/w, or from about 20% to about 23% w/w, or from about 20% to about 22% w/w, or from about 20% to about 21% w/w, or from about 21% to about 25% w/w, or from about 21% to about 24% w/w, or from about 21% to about 23% w/w, or from about 21% to about 22% w/w, or from about 22% to about 25% w/w, or from about 22% to about 24% w/w, or from about 22% to about 23% w/w, or from about 23% to about 25% w/w, or from about 23% to about 24% w/w, or from about 24% to about 25% w/w, or about 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, or about 20.32% or about 21.67% w/w of the aqueous coating composition. [00139] According to another embodiment, the concentration of potassium bicarbonate may be from about 19% to about 43% w/w, or from about 19% to about 42% w/w, or from about 19% to about 41% w/w, or from about 19% to about 40% w/w, or from about 19% to about 39% w/w, or from about 19% to about 38% w/w, or from about 19% to about 37% w/w, or from about 19% to about 36% w/w, or from about 19% to about 35% w/w, or from about 19% to about 34% w/w, or from about 19% to about 33% w/w, or from about 19% to about 32% w/w, or from about 19% to about 31% w/w, or from about 19% to about 30% w/w, or from about 19% to about 29% w/w, or from about 19% to about 28% w/w, or from about 19% to about 27% w/w, or from about 19% to about 26% w/w, or from about 19% to about 25% w/w, or from about 19% to about 24% w/w, or from about 19% to about 23% w/w, or from about 19% to about 22% w/w, or from about 19% to about 21% w/w, or from about 19% to about 20% w/w, or from about 20% to about 43% w/w, or from about 20% to about 42% w/w, or from about 20% to about 41% w/w, or from about 20% to about 40% w/w, or from about 20% to about 39% w/w, or from about 20% to about 38% w/w, or from about 20% to about 37% w/w, or from about 20% to about 36% w/w, or from about 20% to about 35% w/w, or from about 20% to about 34% w/w, or from about 20% to about 33% w/w, or from about 20% to about 32% w/w, or from about 20% to about 31% w/w, or from about 20% to about 30% w/w, or from about 20% to about 29% w/w, or from about 20% to about 28% w/w, or from about 20% to about 27% w/w, or from about 20% to about 26% w/w, or from about 20% to about 25% w/w, or from about 20% to about 24% w/w, or from about 20% to about 23% w/w, or from about 20% to about 22% w/w, or from about 20% to about 21% w/w, or from about 21% to about 43% w/w, or from about 21% to about 42% w/w, or from about 21% to about 41% w/w, or from about 21% to about 40% w/w, or from about 21% to about 39% w/w, or from about 21% to about 38% w/w, or from about 21% to about 37% w/w, or from about 21% to about 36% w/w, or from about 21% to about 35% w/w, or from about 21% to about 34% w/w, or from about 21% to about 33% w/w, or from about 21% to about 32% w/w, or from about 21% to about 31% w/w, or from about 21% to about 30% w/w, or from about 21% to about 29% w/w, or from about 21% to about 28% w/w, or from about 21% to about 27% w/w, or from about 21% to about 26% w/w, or from about 21% to about 25% w/w, or from about 21% to about 24% w/w, or from about 21% to about 23% w/w, or from about 21% to about 22% w/w, or from about 22% to about 43% w/w, or from about 22% to about 42% w/w, or from about 22% to about 41% w/w, or from about 22% to about 40% w/w, or from about 22% to about 39% w/w, or from about 22% to about 38% w/w, or from about 22% to about 37% w/w, or from about 22% to about 36% w/w, or from about 22% to about 35% w/w, or from about 22% to about 34% w/w, or from about 22% to about 33% w/w, or from about 22% to about 32% w/w, or from about 22% to about 31% w/w, or from about 22% to about 30% w/w, or from about 22% to about 29% w/w, or from about 22% to about 28% w/w, or from about 22% to about 27% w/w, or from about 22% to about 26% w/w, or from about 22% to about 25% w/w, or from about 22% to about 24% w/w, or from about 22% to about 23% w/w, or from about 23% to about 43% w/w, or from about 23% to about 42% w/w, or from about 23% to about 41% w/w, or from about 23% to about 40% w/w, or from about 23% to about 39% w/w, or from about 23% to about 38% w/w, or from about 23% to about 37% w/w, or from about 23% to about 36% w/w, or from about 23% to about 35% w/w, or from about 23% to about 34% w/w, or from about 23% to about 33% w/w, or from about 23% to about 32% w/w, or from about 23% to about 31% w/w, or from about 23% to about 30% w/w, or from about 23% to about 29% w/w, or from about 23% to about 28% w/w, or from about 23% to about 27% w/w, or from about 23% to about 26% w/w, or from about 23% to about 25% w/w, or from about 23% to about 24% w/w, or from about 24% to about 43% w/w, or from about 24% to about 42% w/w, or from about 24% to about 41% w/w, or from about 24% to about 40% w/w, or from about 24% to about 39% w/w, or from about 24% to about 38% w/w, or from about 24% to about 37% w/w, or from about 24% to about 36% w/w, or from about 24% to about 35% w/w, or from about 24% to about 34% w/w, or from about 24% to about 33% w/w, or from about 24% to about 32% w/w, or from about 24% to about 31% w/w, or from about 24% to about 30% w/w, or from about 24% to about 29% w/w, or from about 24% to about 28% w/w, or from about 24% to about 27% w/w, or from about 24% to about 26% w/w, or from about 24% to about 25% w/w, or from about 25% to about 43% w/w, or from about 25% to about 42% w/w, or from about 25% to about 41% w/w, or from about 25% to about 40% w/w, or from about 25% to about 39% w/w, or from about 25% to about 38% w/w, or from about 25% to about 37% w/w, or from about 25% to about 36% w/w, or from about 25% to about 35% w/w, or from about 25% to about 34% w/w, or from about 25% to about 33% w/w, or from about 25% to about 32% w/w, or from about 25% to about 31% w/w, or from about 25% to about 30% w/w, or from about 25% to about 29% w/w, or from about 25% to about 28% w/w, or from about 25% to about 27% w/w, or from about 25% to about 26% w/w, or from about 25% to about 43% w/w, or from about 25% to about 42% w/w, or from about 25% to about 41% w/w, or from about 25% to about 40% w/w, or from about 25% to about 39% w/w, or from about 25% to about 38% w/w, or from about 25% to about 37% w/w, or from about 25% to about 36% w/w, or from about 25% to about 35% w/w, or from about 25% to about 34% w/w, or from about 25% to about 33% w/w, or from about 25% to about 32% w/w, or from about 25% to about 31% w/w, or from about 25% to about 30% w/w, or from about 25% to about 29% w/w, or from about 25% to about 28% w/w, or from about 25% to about 27% w/w, or from about 26% to about 43% w/w, or from about 26% to about 42% w/w, or from about 26% to about 41% w/w, or from about 26% to about 40% w/w, or from about 26% to about 39% w/w, or from about 26% to about 38% w/w, or from about 26% to about 37% w/w, or from about 26% to about 36% w/w, or from about 26% to about 35% w/w, or from about 26% to about 34% w/w, or from about 26% to about 33% w/w, or from about 26% to about 32% w/w, or from about 26% to about 31% w/w, or from about 26% to about 30% w/w, or from about 26% to about 29% w/w, or from about 26% to about 28% w/w, or from about 27% to about 43% w/w, or from about 27% to about 42% w/w, or from about 27% to about 41% w/w, or from about 27% to about 40% w/w, or from about 27% to about 39% w/w, or from about 27% to about 38% w/w, or from about 27% to about 37% w/w, or from about 27% to about 36% w/w, or from about 27% to about 35% w/w, or from about 27% to about 34% w/w, or from about 27% to about 33% w/w, or from about 27% to about 32% w/w, or from about 27% to about 31% w/w, or from about 27% to about 30% w/w, or from about 27% to about 29% w/w, or from about 29% to about 43% w/w, or from about 29% to about 42% w/w, or from about 29% to about 41% w/w, or from about 29% to about 40% w/w, or from about 29% to about 39% w/w, or from about 29% to about 38% w/w, or from about 29% to about 37% w/w, or from about 29% to about 36% w/w, or from about 29% to about 35% w/w, or from about 29% to about 34% w/w, or from about 29% to about 33% w/w, or from about 29% to about 32% w/w, or from about 29% to about 31% w/w, or from about 29% to about 30% w/w, or from about 30% to about 43% w/w, or from about 30% to about 42% w/w, or from about 30% to about 41 % w/w, or from about 30% to about 40% w/w, or from about 30% to about 39% w/w, or from about 30% to about 38% w/w, or from about 30% to about 37% w/w, or from about 30% to about 36% w/w, or from about 30% to about 35% w/w, or from about 30% to about 34% w/w, or from about 30% to about 33% w/w, or from about 30% to about 32% w/w, or from about 30% to about 31% w/w, or from about 31% to about 43% w/w, or from about 31% to about 42% w/w, or from about 31% to about 41% w/w, or from about 31% to about 40% w/w, or from about 31% to about 39% w/w, or from about 31% to about 38% w/w, or from about 31% to about 37% w/w, or from about 31% to about 36% w/w, or from about 31% to about 35% w/w, or from about 31% to about 34% w/w, or from about 31% to about 33% w/w, or from about 31% to about 32% w/w, or from about 32% to about 43% w/w, or from about 32% to about 42% w/w, or from about 32% to about 41% w/w, or from about 32% to about 40% w/w, or from about 32% to about 39% w/w, or from about 32% to about 38% w/w, or from about 32% to about 37% w/w, or from about 32% to about 36% w/w, or from about 32% to about 35% w/w, or from about 32% to about 34% w/w, or from about 32% to about 33% w/w, or from about 33% to about 43% w/w, or from about 33% to about 42% w/w, or from about 33% to about 41% w/w, or from about 33% to about 40% w/w, or from about 33% to about 39% w/w, or from about 33% to about 38% w/w, or from about 33% to about 37% w/w, or from about 33% to about 36% w/w, or from about 33% to about 35% w/w, or from about 33% to about 34% w/w, or from about 34% to about 43% w/w, or from about 34% to about 42% w/w, or from about 34% to about 41% w/w, or from about 34% to about 40% w/w, or from about 34% to about 39% w/w, or from about 34% to about 38% w/w, or from about 34% to about 37% w/w, or from about 34% to about 36% w/w, or from about 34% to about 35% w/w, or from about 35% to about 43% w/w, or from about 35% to about 42% w/w, or from about 35% to about 41% w/w, or from about 35% to about 40% w/w, or from about 35% to about 39% w/w, or from about 35% to about 38% w/w, or from about 35% to about 37% w/w, or from about 35% to about 36% w/w, or from about 36% to about 43% w/w, or from about 36% to about 42% w/w, or from about 36% to about 41% w/w, or from about 36% to about 40% w/w, or from about 36% to about 39% w/w, or from about 36% to about 38% w/w, or from about 36% to about 37% w/w, or from about 37% to about 43% w/w, or from about 37% to about 42% w/w, or from about 37% to about 41% w/w, or from about 37% to about 40% w/w, or from about 37% to about 39% w/w, or from about 37% to about 38% w/w, or from about 38% to about 43% w/w, or from about 38% to about 42% w/w, or from about 38% to about 41% w/w, or from about 38% to about 40% w/w, or from about 38% to about 39% w/w, or from about 39% to about 43% w/w, or from about 39% to about 42% w/w, or from about 39% to about 41% w/w, or from about 39% to about 40% w/w, or from about 40% to about 43% w/w, or from about 40% to about 42% w/w, or from about 40% to about 41% w/w, or from about 41% to about 43% w/w, or from about 41% to about 42% w/w, or from about 42% to about 43% w/w, or 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, or 31.58% w/w of the aqueous coating composition.
[00140] According to embodiments, the equivalent U2O molar content should be between about 17% and about 74% of the composition. The equivalent U2O molar content may be provided from a lithium salt which may be selected from the group consisting of lithium carbonate (U2CO3), lithium bicarbonate (UHCO3), LiF, a mixture of LiF and NaF, and combination of all of the above.
[00141] The equivalent molar ratio for lithium salts may be derived according to the following:
Reaction Molar equivalent
1 mole de U2CO3 = 2 moles of Lithium and thus 1 mole
U2CO3 = U2O + C02 de U2O equivalent 2 LiHCOa = U2O + 2 CO2 + H2O 2 moles of L1HCO3 = 1 mole of U2O equivalent
1 mole de LiF = 1 mole de lithium and thus 1/2 mole de LiF L12O equivalent
[00142] The equivalent U2O molar content may be from about 17% to about 74% of the composition, or from about 20% to about 74%, or from about 25% to about 74%, or from about 30% to about 74%, or from about 35% to about 74%, or from about 40% to about 74%, or from about 45% to about 74%, or from about 50% to about 74%, or from about 55% to about 74%, or from about 60% to about 74%, or from about 65% to about 74%, or from about 70% to about 74%, or from 17% to about 70%, or from about 20% to about 70%, or from about 25% to about 70%, or from about 30% to about 70%, or from about 35% to about 70%, or from about 40% to about 70%, or from about 45% to about 70%, or from about 50% to about 70%, or from about 55% to about 70%, or from about 60% to about 70%, or from about 65% to about 70%, or from 17% to about 65%, or from about 20% to about 65%, or from about 25% to about 65%, or from about 30% to about 70%, or from about 35% to about 65%, or from about 40% to about 65%, or from about 45% to about 65%, or from about 50% to about 65%, or from about 55% to about 65%, or from about 60% to about 65%, or from 17% to about 60%, or from about 20% to about 60%, or from about 25% to about 60%, or from about 30% to about 60%, or from about 35% to about 60%, or from about 40% to about 60%, or from about 45% to about 60%, or from about 50% to about 60%, or from about 55% to about 60%, or from 17% to about 55%, or from about 20% to about 55%, or from about 25% to about 55%, or from about 30% to about 55%, or from about 35% to about 55%, or from about 40% to about 55%, or from about 45% to about 55%, or from about 50% to about 55%, or from 17% to about 50%, or from about 20% to about 50%, or from about 25% to about 50%, or from about 30% to about 50%, or from about 35% to about 50%, or from about 40% to about 50%, or from about 45% to about 50%, or from 17% to about 45%, or from about 20% to about 45%, or from about 25% to about 45%, or from about 30% to about 45%, or from about 35% to about 45%, or from about 40% to about 45%, or from 17% to about 40%, or from about 20% to about 40%, or from about 25% to about 40%, or from about 30% to about 40%, or from about 35% to about 40%, or from 17% to about 35%, or from about 20% to about 35%, or from about 25% to about 35%, or from about 30% to about 35%, or from 17% to about 30%, or from about 20% to about 30%, or from about 25% to about 30%, or from 17% to about 25%, or from about 20% to about 25%, or from 17% to about 20%, or 17%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 74% of the composition.
[00143] In a preferred embodiment, the lithium salt is lithium carbonate. In a preferred embodiment, the lithium carbonate may be in suspension in the aqueous coating composition. The lithium carbonate may be any powdered form of lithium carbonate. However, smaller particles may be used in order to favor the homogeneity of the suspension. For example, nano-sized particles of lithium carbonate may be used to obtain stable suspensions.
[00144] Lithium bicarbonate may also be used in the composition of the present invention. It is however mostly available in solution form at maximum concentration of 5.39% w/w.
[00145] According to embodiments, the concentration of the lithium carbonate may be from about 8% to about 18% w/w, or from about 8% to about 17% w/w, or from about 8% to about 16% w/w, or from about 8% to about 15% w/w, or from about 8% to about 14% w/w, or from about 8% to about 13% w/w, or from about 8% to about 12% w/w, or from about 8% to about 11% w/w, or from about 8% to about 10% w/w, or from about 8% to about 9% w/w, or from about 9% to about 18% w/w, or from about 9% to about 17% w/w, or from about 9% to about 16% w/w, or from about 9% to about 15% w/w, or from about 9% to about 14% w/w, or from about 9% to about 13% w/w, or from about 9% to about 12% w/w, or from about 9% to about 11% w/w, or from about 9% to about 10% w/w, or from about 10% to about 18% w/w, or from about 10% to about 17% w/w, or from about 10% to about 16% w/w, or from about 10% to about 15% w/w, or from about 10% to about 14% w/w, or from about 10% to about 13% w/w, or from about 10% to about 12% w/w, or from about 10% to about 11% w/w, or from about 11% to about 18% w/w, or from about 11% to about 17% w/w, or from about 11% to about 16% w/w, or from about 11% to about 15% w/w, or from about 11% to about 14% w/w, or from about 11% to about 13% w/w, or from about 11% to about 12% w/w, or from about 12% to about 18% w/w, or from about 12% to about 17% w/w, or from about 12% to about 16% w/w, or from about 12% to about 15% w/w, or from about 12% to about 14% w/w, or from about 12% to about 13% w/w, or from about 13% to about 18% w/w, or from about 13% to about 17% w/w, or from about 13% to about 16% w/w, or from about 13% to about 15% w/w, or from about 13% to about 14% w/w, or from about 14% to about 18% w/w, or from about 14% to about 17% w/w, or from about 14% to about 16% w/w, or from about 14% to about 15% w/w, or from about 15% to about 18% w/w, or from about 15% to about 17% w/w, or from about 15% to about 16% w/w, or from about 16% to about 18% w/w, or from about 17% to about 17% w/w, or from about 17% to about 18% w/w, or 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or 13.83% to about 14.74% w/w, or 13.83% w/w, or 14.74% w/w of the aqueous coating composition.
[00146] According to another embodiment, the LiF or LiF mixed with NaF may be used as salts of lithium according to concentrations that provide the adequate equivalent U2O molar content.
[00147] According to another embodiment, the aqueous coating of the present invention may further comprise a liquid binder. As used herein, the term “liquid binder” means a liquid or a colloidal suspension that can, bind at room temperature, following chemical transformations such as reactions, gelling or hydration, a set of particles. The latter, originally in the pulverulent state, are transformed by the action of the liquid binder into a rigid material (non-zero modulus of elasticity). The liquid binder may comprise colloidal silica, colloidal alumina, a deflocculant and combinations thereof.
[00148] In embodiments, the concentration of colloidal silica may be up to 5% w/w, or up to
4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 5%, or about 0.5%, 1%, 2%, 3%, 4%, 5%, or 0.65% w/w of the aqueous coating composition. [00149] In embodiments, the concentration of colloidal alumina may be up to 8% w/w, or up to
7% w/w, or up to 6% w/w, or up to 5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1% w/w, or up to 0.5%, or from about 0.5% to about 8%, or from about 0.5% to about 7%, or from about 0.5% to about 6%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 8%, or from about 1% to about 7%, or from about 1% to about 6%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 8%, or from about 2% to about 7%, or from about 2% to about 6%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 8%, or from about 3% to about 7%, or from about 3% to about 6%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 8%, or from about 4% to about 7%, or from about 4% to about 6%, or from about 4% to about 5%, or from about 5% to about 8%, or from about 5% to about 7%, or from about 5% to about 6%, or from about 6% to about 8%, or from about 6% to about 7%, or from about 7% to about 8%, or about 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 5.55% w/w of the aqueous coating composition.
[00150] In embodiments, the liquid binder may also comprise a deflocculant, which is a compound that is added to the composition to minimize settling out, prevent flocculation and disperse the other ingredients, increase fluidity of the composition, and help form a colloid or suspension. The deflocculant may be selected from the group consisting of polyethylene glycol graft polymers, such as castament® FS10, FS20 or FS60.
[00151] In embodiments, the concentration of the deflocculant may be up to 6% w/w, or up to
5% w/w, or up to 4% w/w, or up to 3% w/w, or up to 2% w/w, or up to 1 % w/w, or up to 0.5%, or from about 0.5% to about 6%, or from about 0.5% to about 5%, or from about 0.5% to about 4%, or from about 0.5% to about 3%, or from about 0.5% to about 2%, or from about 0.5% to about 1%, or from about 1% to about 6%, or from about 1% to about 5%, or from about 1% to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 6%, or from about 2% to about 5%, or from about 2% to about 4%, or from about 2% to about 3%, or from about 3% to about 6%, or from about 3% to about 5%, or from about 3% to about 4%, or from about 4% to about 6%, or from about 4% to about 5%, or from about 5% to about 6%, or about 0.5%, 1%, 2%, 3%, 4%, 5%, 6% w/w of the aqueous coating composition.
[00152] In embodiments, the layer aqueous coating composition may have a wet film thickness of about 0.15 mm to about 0.50 mm, or a wet film thickness of about 0.25 ± 0.05 mm. In embodiments, the layer aqueous coating composition may have a residual water content of about 12% w/w or less. [00153] In another embodiment there is disclosed a method of coating a carbon material with a chemical treatment for preventing or reducing air oxidation of the carbon material, the chemical treatment comprising a first layer comprising an aqueous priming coating composition covering an external surface exposed to air of the carbon material; and a second layer, covering the first layer, comprising an aqueous coating composition.
[00154] In embodiments, the aqueous priming coating composition comprises a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water, as detailed above.
[00155] In embodiments, the aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C.
[00156] In embodiments, when applying the aqueous coating composition to the dry layer, the dry layer has a surface temperature of about 74°C to about 100°C. In embodiments, the aqueous coating composition is applied at a temperature of about 48°C to about 52°C.
[00157] According to another embodiment, there is disclosed a system for coating a carbon material with a fluid coating composition for covering an external surface exposed to air of the carbon material. The system comprises a spray gun, and an apparatus for producing an air curtain.
[00158] The spray gun is configured to apply to the external surface a stream of fluid coating composition pressurized at about 200 to about 415 kPa, or from about 200 to about 400 kPa, or from about 200 to about 350 kPa, or from about 200 to about 300 kPa, or from about 200 to about 250 kPa, or from about 250 to about 415 kPa, or from about 250 to about 400 kPa, or from about 250 to about 350 kPa, or from about 250 to about 300 kPa, or from about 300 to about 415 kPa, or from about 300 to about 400 kPa, or from about 300 to about 350 kPa, or from about 350 to about 415 kPa, or from about 350 to about 400 kPa, or from about 400 to about 415 kPa.
[00159] The fluid coating composition may be streamed through gas at about 275 kPa to about 414kPa, or from about 275 kPa to about 400 kPa, or from about 275 kPa to about 350 kPa, or about 275 kPa to about 300 kPa, or about 300 kPa to about 414kPa, or from about 300 kPa to about 400 kPa, or from about 300 kPa to about 350 kPa, or about 350 kPa to about 414kPa, or from about 350 kPa to about 400 kPa, or about 400 kPa to about 414kPa. For example, the fluid coating composition may be streamed through a paint gun configured to stream of air at the indicated pressure. [00160] The spray gun may be positioned at a first distance from said external surface of about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, or about 25 cm to about 30 cm, or 8, 10, 15, 20, 25, or 30, perpendicular to said external surface.
[00161] The apparatus for producing an air curtain is configured to apply a curtain of air at a velocity of about 35 m/s to about 55 m/s, or about 35 m/s to about 50 m/s, or about 35 m/s to about 45 m/s, or about 35 m/s to about 40 m/s, or about 40 m/s to about 55 m/s, or about 40 m/s to about
50 m/s, or about 40 m/s to about 45 m/s, or about 45 m/s to about 55 m/s, or about 45 m/s to about
50 m/s, or about 50 m/s to about 55 m/s, or about 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, and 55, also perpendicular to the external surface being coated.
[00162] The curtain of air is applied from a second distance from the external surface of about 10 mm to about 40 mm, or about 10 mm to about 35 mm, or about 10 mm to about 30 mm, or about
10 mm to about 25 mm, or about 10 mm to about 20 mm, or about 10 mm to about 15 mm, or about
12 mm to about 40 mm, or about 12 to about 35 mm, or about 12 mm to about 30 mm, or about 12 mm to about 25 mm, or about 12 mm to about 20 mm, or about 12 mm to about 15 mm, or 13 mm to about 40 mm, 13 about to about 35 mm, or about 13 mm to about 30 mm, or about 13 mm to about 25 mm, or about 13 mm to about 20 mm, or about 13 mm to about 15 mm, or 14 mm to about 40 mm, or about 14 mm to about 35 mm, or about 14 mm to about 30 mm, or about 14 mm to about 25 mm, or about 14 mm to about 20 mm, or about 14 mm to about 15 mm, or 16 mm to about 40 mm, or about 16 mm to about 35 mm, or about 16 mm to about 30 mm, or about 16 mm to about 25 mm, or about 16 mm to about 20 mm, or 18 mm to about 40 mm, or about 18 mm to about 35 mm, or about 18 mm to about 30 mm, or about 18 mm to about 25 mm, or 20 mm to about 40 mm, or about 20 mm to about 35 mm, or about 20 mm to about 30 mm, or 25 mm to about 40 mm, or about 25 mm to about 35 mm, or about 25 mm to about 30 mm, or 30 mm to about 40 mm, or about 30 mm to about 35 mm, or 35 mm to about 40 mm, or about 10, 15, 20, 25, 30, 35, or 40 mm, perpendicular to the external surface.
[00163] The system is configured for application of the fluid coating composition as a stream under pressure simultaneously with the air curtain, to provide an even distribution of the fluid coating composition.
[00164] In embodiments, the spray gun may provide an application pattern of from about 8 cm to about 40 cm, or about 8 cm to about 35 cm, or about 8 cm to about 30 cm, or from about 8 cm to about 25 cm, or from about 8 cm to about 20 cm, or from about 8 cm to about 15 cm, or from about 8 cm to about 10 cm, from about 10 cm to about 40 cm, or about 10 cm to about 35 cm, or about 10 cm to about 30 cm, or from about 10 cm to about 25 cm, or from about 10 cm to about 20 cm, or from about 10 cm to about 15 cm, from about 15 cm to about 40 cm, or about 15 cm to about 35 cm, or about 15 cm to about 30 cm, or from about 15 cm to about 25 cm, or from about 15 cm to about 20 cm, from about 20 cm to about 40 cm, or about 20 cm to about 35 cm, or about 20 cm to about 30 cm, or from about 20 cm to about 25 cm, from about 25 cm to about 40 cm, or about 25 cm to about 35 cm, or about 25 cm to about 30 cm, or from about 30 cm to about 40 cm, or about 30 cm to about 35 cm, or from about 35 cm to about 40 cm, or 8, 10, 15, 20, 25, 30, 35, or 40 cm.
[00165] In embodiments, applying the stream of fluid coating composition may be performed at a flow rate of about 0.4 L/min to about 1 L/min, or about 0.4 L/min to about 0.9 L/min, or about 0.4 L/min to about 0.8 L/min, or about 0.4 L/min to about 0.7 L/min, or about 0.4 L/min to about 0.6L/min, or about 0.4 L/min to about 0.5 L/min, or about 0.5 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.5 L/min to about 0.8 L/min, or about 0.5 L/min to about 0.7 L/min, or about 0.5 L/min to about 0.6L/min, or about 0.6 L/min to about 1 L/min, or about 0.5 L/min to about 0.9 L/min, or about 0.6 L/min to about 0.8 L/min, or about 0.6 L/min to about 0.7 L/min, or about 0.7 L/min to about 1 L/min, or about 0.7 L/min to about 0.9 L/min, or about 0.7 L/min to about 0.8 L/min, or about 0.8 L/min to about 1 L/min, or about 0.8 L/min to about 0.9 L/min, or about 0.9 L/min to about 1 L/min, or about 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95. 1.0 L/min.
[00166] In embodiments, the spray gun and the apparatus for producing an air curtain are displaced perpendicular to the external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec, or from about 2 cm/sec to about 18 cm/sec, or from about 2 cm/sec to about 16 cm/sec, or from about 2 cm/sec to about 15 cm/sec, or from about 2 cm/sec to about 14 cm/sec, or from about 2 cm/sec to about 12 cm/sec, or from about 2 cm/sec to about 10 cm/sec, or from about 2 cm/sec to about 8 cm/sec, or from about 2 cm/sec to about 6 cm/sec, or from about 2 cm/sec to about 4 cm/sec, or about 4 cm/sec to about 20 cm/sec, or from about 4 cm/sec to about 18 cm/sec, or from about 4 cm/sec to about 16 cm/sec, or from about 4 cm/sec to about 15 cm/sec, or from about 4 cm/sec to about 14 cm/sec, or from about 4 cm/sec to about 12 cm/sec, or from about 4 cm/sec to about 10 cm/sec, or from about 4 cm/sec to about 8 cm/sec, or from about 4 cm/sec to about 6 cm/sec, or about 6 cm/sec to about 20 cm/sec, or from about 6 cm/sec to about 18 cm/sec, or from about 6 cm/sec to about 16 cm/sec, or from about 6 cm/sec to about 15 cm/sec, or from about 6 cm/sec to about 14 cm/sec, or from about 6 cm/sec to about 12 cm/sec, or from about 6 cm/sec to about 10 cm/sec, or from about 6 cm/sec to about 8 cm/sec, or about 8 cm/sec to about 20 cm/sec, or from about 8 cm/sec to about 18 cm/sec, or from about 8 cm/sec to about 16 cm/sec, or from about 8 cm/sec to about 15 cm/sec, or from about 8 cm/sec to about 14 cm/sec, or from about 8 cm/sec to about 12 cm/sec, or from about 8 cm/sec to about 10 cm/sec, or about 10 cm/sec to about 20 cm/sec, or from about 10 cm/sec to about 18 cm/sec, or from about 10 cm/sec to about 16 cm/sec, or from about 10 cm/sec to about 15 cm/sec, or from about 10 cm/sec to about 14 cm/sec, or from about 10 cm/sec to about 12 cm/sec, or about 12 cm/sec to about 20 cm/sec, or from about 12 cm/sec to about 18 cm/sec, or from about 12 cm/sec to about 16 cm/sec, or from about 12 cm/sec to about 15 cm/sec, or from about 12 cm/sec to about 14 cm/sec, or about 14 cm/sec to about 20 cm/sec, or from about 14 cm/sec to about 18 cm/sec, or from about 14 cm/sec to about 16 cm/sec, or from about 14 cm/sec to about 15 cm/sec, or about 15 cm/sec to about 20 cm/sec, or from about 15 cm/sec to about 18 cm/sec, or from about 15 cm/sec to about 16 cm/sec, or about 16 cm/sec to about 20 cm/sec, or from about 16 cm/sec to about 18 cm/sec, or about 18 cm/sec to about 20 cm/sec, or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15,16, 17, 18, 19, or 20 cm/sec.
[00167] According to another embodiment, a distance between a central axis of the spray gun and a central axis of the apparatus for producing an air curtain may be from about 100 mm to about 300 mm, or about 100 mm to about 250 mm, or about 100 mm to about 200 mm, or about 100 mm to about 150 mm, or about 100 mm to about 125 mm, or about 125 mm to about 300 mm, or about 125 mm to about 250 mm, or about 125 mm to about 200 mm, or about 125 mm to about 150 mm, or about 150 mm to about 300 mm, or about 150 mm to about 250 mm, or about 150 mm to about 200 mm, or about 200 mm to about 300 mm, or about 200 mm to about 250 mm, or about 250 mm to about 300 mm, or 100, 125, 150, 200, 250, or 300 mm.
[00168] According to another embodiment, the system of the present invention may further comprise a fluid coating composition reservoir, in fluid communication with said spray gun. The fluid coating composition reservoir is a high-pressure reservoir. The fluid coating composition reservoir may further comprises an agitator.
[00169] According to another embodiment, the system of the present invention may further comprise a compressor in fluid communication with the apparatus for producing an air curtain, to provide compressed air thereto.
[00170] According to another embodiment, the system of the present invention may further comprise an air dehumidifier.
[00171] In the system of the present invention, the fluid coating composition may be an aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water, as described above. [00172] In another embodiment, in the system of the present invention, the fluid coating composition may be an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, the aqueous coating composition having a melting temperature of up to about 600°C, which may be applied over a dry layer of the aqueous priming coating composition described above.
[00173] The present invention will be more readily understood by referring to the following examples which are given to illustrate the invention rather than to limit its scope.
EXAMPLE 1
COATING OF CARBON ANODE
[00174] Now referring to Fig. 1 , which illustrates schematically the method of coating according to an embodiment of the present invention. The stream of coating 20 and the air curtain 18 are shown as side by side, but as described below in the parameters of the present method, coating stream and air curtain are applied simultaneously such that when the coating contacts the external surface (i.e. coated anode 12) of the carbon material (anode 10), it is already under the influence of the air curtain that will contribute to its spread across the surface.
[00175] The coating may be applied to the surface with a conventional spray gun 16 by mixing the coating at 30 to 40 psi, preferably 30 psi (i.e. 200 to about 280 kPa) of pressure with streaming of gas (i.e. air) current at a pressures (e.g. about 275 kPa to about 414 kPa). The coating pressure is set at these values to produce a layer with a wet film thickness of about 0.125 mm.
[00176] The spray gun 16 may be placed perpendicularly to and about 10 cm (4 inches) from the surface. These specific parameters produce a lightly dense stream of coating that drips on the surface of the carbon anode 10, simulating a coating shower.
[00177] In the same structure, to provide the simultaneous air curtain, an air output is located at 5 inches (about 12.7 cm) from the air gun (although it could be located anywhere near the air-gun, as long at the stream of coating 20 is avoided) and at about 2 inches (about 5.1 cm) from the anode surface (although this distance could be varied, as long as the targeted air velocity of 35 m/s to 45 m/s, preferably 42 m/s is obtained near the surface of the carbon anode 10), resulting in a system formed by the air gun and the air output. The air output is connected to an air blower that supplies the air so that the speed at the contact area with the external surface of the carbon anode 10 is close to 42 m/s. In the illustrated embodiment, the air curtain 18 is blown perpendicularly to the carbon anode 10 surface through a rectangular groove 22. See Fig. 2. [00178] In order to test the hardest conditions, one face of the anode was selected as a sample. The top section is notably more porous than the others faces of the carbon anode 10; it also shows in most of the cases the very uneven structure of pores.
[00179] The system moves parallel to the carbon anode 10 face selected. The parameters for the air gun were set so that the fan width was about 6 inches. Additionally, the air output had a length of 10 inches, and it was placed centered with the gun to ensure that one third of the section of the face was covered with one pass as is shown in Fig. 3.
[00180] To start the coating application, the air gun is turned on at the edge of the face. At the same time that the system begins to move along the anode, the air curtain that is simultaneously applied forces the coating stream to flow into the pores, waves and asperities of the carbon anode 10 and spreads evenly on the surface. While the system moves along the surface, this effect is reproduced until a thin uniform layer of coating is achieved all over the surface section. Fig. 4 a close up of the coated surface can be seen.
[00181] Several tests were made and evaluated qualitatively based on 5 different behaviours of the distribution of the coating in the pores. Table 1 below shows the scale used in the study.
Figure imgf000040_0001
Table 1 - Distribution of the coating in the pores.
[00182] All the tests performed showed 100% of the pores, waves and asperities filled up by the coating and the distribution of the coating was even all along the surface.
[00183] During the tests, the wet film thickness of the layers was measured using a wet film thickness gauge (Wet Film Thickness Gauge, Dual Scale Micron & Mils). The results showed a thickness from 0.100 to 0.150 mm, which indicates a wet film thickness that approaches greatly to the one required.
[00184] Since this method is being developed as part of a coating process, some tests were made as a complement in order to verify the ability of the layer to be overcoated with the second and third layer of coating. A section of the anode was coated in 3 steps: the first layer was applied with the method described in this study and the second and third layers were applied using a conventional spray coating method. The final look of this section is show in Fig. 5.
[00185] As can be seen, the results of the test were positive; the coating was properly and evenly spread in the substrate.
EXAMPLE 2
AIR CURTAIN VELOCITY DETERMINATION
[00186] Now referring to Figs. 6-9. Fig. 6 illustrates an air curtain according to a prototypical embodiment of such curtain. Fig. 7 illustrates an air output device comprising a rectangular groove through which such an air curtain may be obtained. In Fig. 8, there is shown a system for determination of the distance between a source of air to obtain an appropriate air velocity at the contact area. The air speed was measured in 3 different points with an anemometer: center (c) and two sides (S1 and S2, as shown in Fig. 6) at 3 different distances (here, 2, 4 or 6 inches - 5.08, 10.16 and 15.24 cm) and the flow of air is profiled. Fig. 9 shows the profiled velocities.
EXAMPLE 3
CONVENTIONAL COMMERCIAL AIRLESS SPRAYING SYSTEM
[00187] Now referring to Fig. 10, in this example, a conventional commercial airless spraying system 100 is used for applying manually three layers of primer on a carbon anode 10 surface (Fig. 10, Top). The total primer wet thickness was about 0.5 mm and its appearance after application of the third (last) layer is shown on Fig. 10, bottom. With such conventional painting technique and heterogeneous material (i.e., the surface 10), it is not possible to fill and cover all surface defects, such as cavities (see Fig. 1 , bottom, unfilled cavities 110), even when increasing the paint final film thickness up to 1 - 1.5 mm. Moreover, this conventional technique does not allow the application of a 0,5 mm thick primer coat in only a single or two layers without causing paint loss by dripping of more than 10 wt. %.
EXAMPLE 4
FIRST EXAMPLE OF SPRAYING SYSTEM
[00188] Now referring to Figs. 11-14, in this example, an automatic painting system of the present invention was used for applying the primer on the top surface of carbon anodes 10 (see Fig. 11). This system uses an automatic paint gun 111 (a BINKS “TROPHY” SERIES AUTOMATIC SPRAY GUNS, from Carlisle), having the specifications in Table 2 below. It is connected to a high- pressure tank with agitator 113 (such as model 236153 from Graco) that contains the primer.
Figure imgf000042_0001
[00189] The system also uses a “WindJet Air Knife” blower 112 to provide an air curtain. The air curtain follows the paint gun 111 during its displacement along the length of the anode 10 (see Fig. 12A and 12B) at constant velocity. The air curtain creates a wake of paint moving at the same velocity as the paint gun 111 on the anode 10 surface, ahead of the blower 112 air slot (see Figs. 13A and 13B). The amount of paint locally carried out by this wake must be just sufficient for filling and/or covering all surface cavities and/or protuberances that can be detected by the naked eye. The blower 112 also increases paint drying rate after each applied layer.
[00190] In this example, the distance between the paint gun 111 and the blower 112 as well as their position with respect to the anode surface were as shown on Fig. 14. The other painting setup parameters were as follow:
Figure imgf000042_0002
Table 3: painting set-up parameters [00191] These parameters allowed to reach an average 0.5 mm thick primer coating on the anode top surface test zone after application of 4 layers. The paint wake ahead of the blower 112 air slot that started to form during application of the fourth layer completely filled the anode 10 surface cavities and also covered its protuberances, at least to the naked eye. Paint loss by dripping was less than 10% wt. The appearance of the final primer coating was similar to that shown on Fig. 11.
EXAMPLE 5
SECOND EXAMPLE OF SPRAYING SYSTEM
[00192] Now referring to Figs. 15-20, in this example, the automatic painting novel system described in example 3 was used to apply the primer on a side surface of two carbon anodes by moving both paint gun and blower along their length (see Fig. 15). The distance between the paint gun 111 and the blower 112, as well as their position with respect to the anode side surface were in both cases as shown on Fig. 16. The other painting set-up parameters were the same as those given in example 2 except the air gun and blower displacement velocity as shown below.
Figure imgf000043_0001
Table 4: painting set-up parameters
[00193] These parameters allowed to reach an average 0.5 mm thick primer coating on the anode 10 side surface test zones after application of 4 layers in both cases (see Figs. 17 to 20). The paint wake ahead of the blower 112 air slot that started to form during the third layer was carrying enough amount of paint to completely fill the anodes 10 surface cavities and covering their protuberances (at least to the naked eye) only during the fourth layer application (see Figs. 18 and 20). Paint loss by dripping was less than 10% wt. in both cases.
EXAMPLE 6
THIRD EXAMPLE OF SPRAYING SYSTEM
[00194] Now referring to Fig. 21 - 23, in this example, the novel automatic painting system described in example 3 was used for applying the primer on a side surface of a carbon anode 10 by moving both paint gun 111 and blower 112 from bottom to top (see Fig. 21). The paint application procedure started at the left side of the anode 10 and was then repeated at different positions toward the right side of anode 10. Paint overlapping between each position was about 50%. [00195] The distance between the paint gun and the blower as well as their position with respect to the anode side surface were as shown on Fig. 22. The other painting set-up parameters were the same as those given in examples 2 and 3 except the air gun and blower displacement velocity as shown below:
Figure imgf000044_0001
Table 5: painting set-up parameters
[00196] These parameters allowed to reach an average 0.5 mm thick primer coating exempt of unfilled cavities and uncovered protuberances (to the naked eye) on the anode 10 side surface test zone after application of only one layer (see Fig. 23). With this configuration the paint wake starts to form during the first paint application and higher amount of paint can be carried out by the wake without exceeding the dripping paint loss limit of 10% wt.
[00197] While preferred embodiments have been described above and illustrated in the accompanying drawings, it will be evident to those skilled in the art that modifications may be made without departing from this disclosure. Such modifications are considered as possible variants comprised in the scope of the disclosure.

Claims

CLAIMS:
1 . A method of coating a carbon material with an aqueous priming coating composition for covering an external surface exposed to air of said carbon material, to form a first layer thereon, the aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water; the method comprising the step of applying to said external surface a stream of said aqueous priming coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa, from a first distance from said external surface of about 8 cm to about 30 cm, perpendicular to said external surface, and simultaneously applying a curtain of air at a velocity of about 35 m/s to about 55 m/s, from a second distance from said external surface of about 10 mm to about 40 mm perpendicular to said external surface, wherein application of said aqueous priming coating composition as a stream under pressure simultaneously with said air curtain provides an even distribution of said aqueous priming coating composition over said external surface.
2. The method of claim 1 , wherein said carbon material is a carbon anode.
3. The method of claim 2, wherein said carbon anode is a prebaked consumable carbon anode.
4. The method of any one of claims 1 to 3, wherein said layer of said aqueous priming coating composition on said external surface has a wet film thickness of about 0.100 mm to about 0.50 mm.
5. The method of claim 4, wherein said layer of said aqueous priming coating composition on said external surface has a wet film thickness of about 0.100 mm to about 0.150 mm.
6. The method of any one of claims 1 to 5, wherein said stream of said aqueous priming coating composition comprises an application pattern of from about 8 cm to about 40 cm.
7. The method of claim 6, wherein said application pattern is from about 20 cm to about 35 cm.
8. The method of any one of claims 1 to 7, wherein applying said stream of said aqueous priming coating composition is at a flow rate of about 0.4 L/min to about 1 L/min.
9. The method of claim 8, wherein said flow rate is of about 0.55 L/min.
10. The method of any one of claims 1 to 9, wherein said velocity is from about 45 m/s to about 50 m/s.
11. The method of claim 10, wherein said velocity is about 42 m/s.
12. The method of any one of claims 1 to 9, wherein said stream of said aqueous priming coating composition and said curtain of air are displaced perpendicular to said external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec.
13. The method of claim 12, wherein said displacement velocity is from about 4 to about 17 cm/sec.
14. The method of any one of claims 1 to 13, wherein multiple applications of said aqueous priming coating composition are made.
15. The method of claim 14, wherein said aqueous priming coating composition is dried at room temperature for about 2 minutes or more, prior to application of a subsequent aqueous priming coating composition layer.
16. The method of any one of claims 1 to 15, wherein when applying said aqueous priming coating composition to said external surface, said external surface has a surface temperature of about 5°C to about 50°C.
17. The method of any one of claims 1 to 16, wherein said aqueous priming coating composition is applied at a temperature of about 5°C to about 50°C.
18. The method of any one of claims 1 to 17, wherein said aqueous priming coating composition is streamed through gas at about 275 kPa.
19. The method of any one of claims 1 to 18, wherein said first distance from said external surface is of about 15 cm to about 20 cm.
20. The method of any one of claims 1 to 18, wherein said first distance from said external surface is of about 10 cm.
21. The method of any one of claims 1 to 20, wherein said second distance from said external surface is of about 13 mm to about 30 mm.
22. The method of any one of claims 1 to 21 , wherein a distance between a central axis of said stream of said aqueous priming coating composition and a central axis of said curtain of air is from about 100 mm to about 300 mm.
23. The method of claim 22, wherein said distance is from about 125 mm to about 200 mm.
24. The method of any one of claims 1 to 23, further comprising applying an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of aqueous priming coating composition.
25. The method of claim 24, wherein said aqueous coating composition forms a layer having a wet film thickness of about 0.15 mm to about 0.50 mm.
26. The method of claim 25, wherein said aqueous coating composition forms a layer having a wet film thickness of about 0.25 ± 0.05 mm.
27. The method of any one of claims 24 to 26, wherein when applying said aqueous coating composition to said dry layer, said dry layer has a surface temperature of about 74°C to about 100°C.
28. The method of any one of claims 24 to 27, wherein said aqueous coating composition is applied at a temperature of about 48°C to about 52°C.
29. The method of any one of claims 14 to 28, wherein a second or more layer of said aqueous priming coating composition is applied by the method of claim 1 , by spray coating, or a combination thereof.
30. A system for coating a carbon material with a fluid coating composition for covering an external surface exposed to air of said carbon material, comprising: a) a spray gun, configured to apply to said external surface a stream of fluid coating composition pressurized at about 200 to about 415 kPa and streamed through gas at about 275 kPa to about 414 kPa, said spray gun positioned at a first distance from said external surface of about 8 cm to about 30 cm, perpendicular to said external surface, b) an apparatus for producing an air curtain, configured to apply a curtain of air at a velocity of about 35 m/s to about 55 m/s, from a second distance from said external surface of about 10 mm to about 40 mm perpendicular to said external surface, wherein said system is configured for application of said fluid coating composition as a stream under pressure simultaneously with said air curtain, to provide an even distribution of said fluid coating composition.
31. The system of claim 30, further comprising a fluid coating composition reservoir, in fluid communication with said spray gun.
32. The system of claim 31 , wherein said fluid coating composition reservoir is a high-pressure reservoir.
33. The system of any one of claims 31 - 32, wherein said fluid coating composition reservoir further comprises an agitator.
34. The system of any one of claims 30 - 33, further comprising a compressor in fluid communication with said apparatus for producing an air curtain, to provide compressed air thereto.
35. The system of any one of claims 30 - 34, further comprising an air dehumidifier.
36. The system of any one of claims 30 to 35, wherein said spray gun provides an application pattern of from about 8 cm to about 40 cm.
37. The system of claims 36, wherein said application pattern is from about 20 cm to about 35 cm.
38. The system of any one of claims 30 to 37, wherein applying said stream of said aqueous priming coating composition is provided at a flow rate of about 0.4 L/min to about 1 L/min.
39. The system of claim 38, wherein said flow rate is of about 0.55 L/min.
40. The system of any one of claims 30 to 39, wherein said velocity is from about 45 m/s to about 50 m/s.
41. The system of claim 40, wherein said velocity is about 42 m/s.
42. The system of any one of claims 30 to 41 , wherein said spray gun and said apparatus for producing an air curtain are displaced perpendicular to said external surface at a displacement velocity of from about 2 cm/sec to about 20 cm/sec.
43. The system of claim 42, wherein said displacement velocity is from about 4 cm/sec to about 17 cm/sec.
44. The system of any one of claims 30 to 43, wherein said spray gun is configured to stream through gas at about 275 kPa.
45. The system of any one of claims 30 to 44, wherein said first distance from said external surface is of about 15 cm to about 20 cm.
46. The system of any one of claims 30 to 44, wherein said first distance from said external surface is of about 10 cm.
47. The system of any one of claims 30 to 46, wherein said second distance from said external surface is of about 13 mm to about 30 mm.
48. The system of any one of claims 30 to 47, wherein a distance between a central axis of said spray gun and a central axis of said apparatus for producing an air curtain is from about 100 mm to about 300 mm.
49. The system of claim 48, wherein said distance is from about 125 mm to about 200 mm.
50. The system of any one of claims 30 to 49, wherein said fluid coating composition is an aqueous priming coating composition comprising a mixture of aluminum oxide (AI2O3), comprising a combination of aluminum oxide selected from the group consisting of calcined aluminum oxide, reactive aluminum oxide, and white fused aluminum oxide; and water.
51. The system of claim 50, wherein said fluid coating composition is an aqueous coating composition comprising a combination of a sodium salt of carbonate and a potassium salt of carbonate providing an equivalent Na20:K20 molar ratio of about 0.4 to about 2.0, and water, said aqueous coating composition having a melting temperature of up to about 600°C, over a dry layer of said aqueous priming coating composition.
PCT/CA2021/050208 2020-02-24 2021-02-23 Method of coating a carbon surface WO2021168551A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090311517A1 (en) * 2005-06-03 2009-12-17 Fumin Corporation Coating process for forming films containing ultraviolet- or infrared-screening agents
US20110262622A1 (en) * 2008-10-24 2011-10-27 Frank Herre Coating device and associated coating method
CA3087436A1 (en) * 2018-09-06 2020-03-12 Laboratoire Cir Inc. Anode coating compositions and uses thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090311517A1 (en) * 2005-06-03 2009-12-17 Fumin Corporation Coating process for forming films containing ultraviolet- or infrared-screening agents
US20110262622A1 (en) * 2008-10-24 2011-10-27 Frank Herre Coating device and associated coating method
CA3087436A1 (en) * 2018-09-06 2020-03-12 Laboratoire Cir Inc. Anode coating compositions and uses thereof

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