RU1799904C - Method for applying protective coating on coal - Google Patents

Abstract

Application: in the coal industry to eliminate coal losses during transportation and transportation in railway cars. The essence of the invention: a protective coating is applied to the surface of the coal by spraying a liquid film-forming composition, which is used as a 10-15% aqueous emulsion of fat tar or a mixture of bottoms of synthetic fatty acids with an aqueous solution of calcium chloride, iron, barium hydroxide or calcium. It is sprayed with a droplet size of 30-100 μm at 20-60 ° C and a flow rate of 0.8-1.4 kg / m of coal surface, a mixture of the bottoms of synthetic fatty acids with an aqueous solution of calcium chloride, iron, barium hydroxide or calcium of 10% concentration is used in equal proportions; a film-forming composition with a dynamic viscosity of 1-5 kPa s and a surface tension of (18-22) -103 N / m is used for spraying. 2 s. P. f-ly, 1 ill., 1 tab.

Description

The invention relates to a technology for applying a protective coating in the coal industry in the process of transferring and transporting coal mines to a far distance in railway cars, where large losses of coal occur due to blowing of coal dust with an oncoming air stream, and can be used to eliminate coal losses in order to increase the protective properties of prophylactic agents forming film-forming coatings.

The aim of the invention is to reduce coal losses.

The goal is achieved in that in the method of applying a protective coating on coal,

including spraying a liquid film-forming composition on the surface of a coal, a 10-15% aqueous emulsion of tar oil or a mixture of bottoms of synthetic fatty acids with an aqueous solution of calcium chloride, iron, barium hydroxide or calcium is used as a film-forming composition, it is sprayed with a droplet size 30-100 microns at 20-60 ° C and a flow rate of 0.8-1.4 kg / m2 surface angle.

In addition, the goal is achieved in that a mixture of VAT residue of synthetic fatty acids with an aqueous solution of calcium chloride, barium hydroxide iron or calVI

th

N

A 10% concentration is used in equal proportions: for spraying, a film-forming composition with a dynamic viscosity of 1-5 kPa and a surface tension of (18-22) -103 N / m is used.

The method of applying a protective coating to coal differs from that known for the technological modes of applying a liquid film-forming composition, which contributes to the effective manifestation of rheological properties when forming a protective coating with a lower composition consumption, lower concentration, excluding the introduction of organic solvents. The compositions of the present invention produce more uniform emulsions in composition than in the known one, where a suspension of coal tar pitch is dissolved in an aromatic solvent with calcium chloride, which requires safe handling conditions.

An environmentally friendly composition, for example, is the proposed aqueous solution of calcium oxide hydrate Ca (OH) 2, which reduces harmful sulfur emissions, freeze-up and eliminates spontaneous combustion of coal, which is important to consider when transporting and preserving from wind erosion. The use of tar, bottoms of synthetic fatty acids allows us to expand the range of substandard raw materials and use waste from local industry, oil extraction and oil refineries to reduce coal losses. The advantage of using an aqueous emulsion of fat or cotton tar is that in a diluted form, when the concentration of the dispersed phase is less than 5%, its stability depends on the electrokinetic potential and the associated thickness of the solvate shell, it remains stable when heated to 60 ° With no special emulsifiers.

Since emulsions are disperse systems in which both the dispersion phase and the dispersion medium are liquid, they refer to microheterogeneous systems consisting of two immiscible (limitedly miscible) liquids, one of them dispersed in the form of small droplets. One of the phases of the emulsion is water. The other phase is an organic to viscous fluid - fatty or cotton tar, which is commonly called oil regardless of its chemical nature. In addition to water and oil, the stable emulsion contains a third emulsifier component. They are caustic soda NaOH or ammonium hydroxide

-

NH40H giving aggregative stability to the emulsion.

The penetration depth of the sprayed (sprayed) liquid composition in the layer

the angle reached not more than 1000 microns and was estimated by the thickness of the protective coating, which was provided by spraying with a droplet size of 30-100 microns at 20-60 ° C, after curing the thickness was not

less than 10-15 microns.

The consumption of the film-forming composition during coating was selected taking into account the heat-humidity conditions, in the viscosity-rheological properties of it and optimal

dynamic viscosity parameters of 1-5 kPa.s and a surface tension of (18-22) -103 N / m. Since coal is transported in railway wagons and the main layer during transportation is the outer layer, we proceeded from the working surface of the wagon loaded with coal. The mass of coal was recalculated based on the volume of the car and the density of coal, i.e.:

25

  V.

Consumption was taken optimal in the amount of 0.8-1.4 kg of liquid film-forming composition per 1 m of coal surface

obtaining an integral coating and forming a protective film with a thickness of at least 10-15 microns, which was not destroyed by the oncoming air flow. In terms of hard coating, this is

approximately 9-15 g / t coal

Modes of air blowing were selected to cool and harden the coatings and to check the quality of the coatings.

Coatings were cooled

in countercurrent motion with a stream of air supplied at a speed of 5 m / s, and at a temperature of 20-35 ° C for 2-3 minutes after coating to form a hardened film.

The speed of the blown air flow to assess the integrity of the coatings is selected based on the conditions of rail transportation 5-30 m / s.

When choosing the composition, the film-forming and rheological properties of the ingredients capable of forming coatings with a sufficiently dense layer were proceeded. At a dynamic viscosity of 1-5 kPa.s with a surface tension of st (18-22) 103 N / m

Within 130-150 seconds of spraying (dispersed spraying) onto the coal, protective coatings were obtained that completely eliminated the loss of coal fines from weathering.

The proposed method is carried out in an installation intended for applying a protective coating to coal (see drawing). According to the flow diagram shown in the drawing, the bottoms of synthetic fatty acids or tar in liquid form are fed to the hopper 1 and fed into the mixing tank 2 in separate portions, where it is prepared to a uniform consistency with a given concentration after the NaOH emulsifier is introduced or NhUOH from tank 4 into water heated to 80-90 ° C and vigorously stirring with stirrer 3 for 15-20 minutes. The resulting emulsion is supplied by spray pump 5 and dispersant (nozzle) 6 in a sprayed form to a coal-loaded car 7, where a protective coating is applied to coal at 20-60 ° C for 130-150 s, after which blowing and cooling.

In the experiments for applying a protective coating, the Tash-Kumyrsky coal fraction of up to 2 and 13 mm and brown coal of the Agulak deposit of a fraction of up to 6 mm were taken.

Example 1. Tash-Kumyrsky coal fraction of up to 2 mm is poured into a railway carriage simulating a carriage. A liquid film-forming composition is sprayed onto the coal surface (before transportation) with a nozzle at 60 ° C for 130 s in the form of a 10% aqueous emulsion of tar oil or smsi consisting of two ingredients (VAT residue of synthetic fatty acid and calcium chloride) 10% concentration with a droplet size of at least 30 μm, a dynamic viscosity of 5 kPa.s and a surface tension of 18-10 N / m.

A specific composition of a 10% aqueous emulsion of fat tar consists of a ratio of 10 parts of water, 1 part of tar and sodium hydroxide emulsifier in the form of a 10% aqueous solution or ammonium hydroxide. The mixture is a stable emulsion, which, after application and coating, cools and hardens at 25-20 ° C. The emulsion is prepared as follows. An emulsifier (caustic soda or ammonium hydroxide) is introduced into a container with a stirrer filled with heated water (80-90 ° C) in the ratio of 10 parts of water and 1 part of sodium hydroxide. Fatty tar heated to a liquid state is introduced into the resulting 10% aqueous NaOH solution with a density of about 1110 kg / m3. The ratio of tar and emulsifier is taken to be 10: 1. The fat tar, under room conditions, has a semi-solid consistency; when heated to 40-60 ° C, it passes into a fluid state. A mixture of tar oil at 40 ° C with an aqueous solution of NaOH emulsifier is intensively mixed in hot water (80 ° C) for 15-20 minutes until a stable emulsion is obtained, after which the emulsion is sprayed onto the surface of the coal loaded into the wagon.

A mixture of bottoms of synthetic fatty acids of 10% aqueous concentration with a 10% aqueous solution of chloride

calcium CaCl2 6H20 or iron FeCkr bNaO is a solution in the form of a homogeneous mixture of two ingredients, which is supplied at 60 ° C before dispersion. Since heat dissipation occurs upon dissolution of iron chloride and calcium chloride in water, the thermal effect is taken into account when preparing them with a still residue of synthetic fatty acids or with fatty tar.

The consumption of the film-forming composition of 0.8 kg / m of the surface of the coal is considered optimal, taking into account the integrity of the protective coating with a thickness of 10 microns. Drop size 30-100 μm selected based on conditions

if not a drop and completely wetting and enveloping the particles of coal. The formation of a film-forming protective coating is carried out until it is completely cured by the counter flow

air at a speed of 5-30 m / s at 20 ° C for 2 minutes After 2 minutes, the film formed and hardened. The protective coating satisfies the quality requirements of the coatings.

Evaluation of the quality of coatings was carried out according to the indicators of strength (integrity) and the thickness of the film, which does not deteriorate when blowing.

PRI me R 2. Applying a protective

coal coating is carried out, as in example 1. Tash-Kumyrsky coal fractions up to 13 mm are poured into a railway carriage and processed for 150 with a sprayed 15% mixture of cubic residue of synthetic fatty acid with calcium chloride or iron chloride or aqueous hydroxide solution bari or calcium. The mixture is prepared as an aqueous tar oil emulsion. Vat

the remainder of the synthetic fatty acids is heated to 60 ° C and upon transition from the solid phase to the liquid phase, an aqueous solution of calcium chloride, or iron chloride, or barium or calcium hydroxide is introduced into it in an equal ratio of 1: 1. The mixture is vigorously mixed for 15 minutes and is fed to the nozzle for spraying. A concentration of 15% is considered critical since aggregates or secondary supramolecular formations appear on such a system, on the surface of which heavy resins are adsorbed.

The aqueous solutions of calcium hydroxide Ca (OH) 2 8 NaO used are slaked lime, or barium Ba (OH) 2 8H20 is a suspension of Ca (OH) a or Ba (OH) 2 in water, which in the first case is called lime water , and in the second - barite water. Lime water is prepared from 1 hour well calcined CaO, pour 4 hours, water. The CaO powder is stirred with water until a homogeneous mass is obtained. The precipitate is allowed to settle and the clear liquid is drained. 50 parts of water are added to the precipitate, stirred until a homogeneous mass is obtained, the flask is tightly closed and the solution is allowed to stand well. The clear solution is drained and water is again poured into the flask with the precipitate to prepare a new portion of the solution. Barium hydroxide Ba (OH) 2 8HaO (caustic barium) is used to prepare barite water, a saturated solution of Ba (OH) 2. To prepare, take 70 g of eight-water barium hydroxide (powder) per 1 liter of water, mix, allow to stand and drain the clear solution. At a consumption of a mixture of a film-forming composition, 4 kg / m2 of coal surface with viscosity; 1 kPa with a surface tension of 22-103 N / m, the droplet size is 100 µm, which provides sufficient wettability of the coal surface and promotes the formation of a protective coating with a hardened film thickness of 15 µm. Complete cure of the formed coating occurs upon cooling. For this, a counter flow of air is supplied at a speed of 5 m / s for 2-3 minutes at 30-35 ° C. The strength of the coating meets the requirements for the protective properties of the coating, and the protective coating does not deteriorate when transported by the blown air stream during transportation.

Example 3. On the surface of the Agulak brown angle, fractions of up to 6 mm are applied in a dispersed form for 150 s, heated to 40 ° C with a 10% aqueous tar oil emulsion with a droplet size of 30 μm. The consumption is taken equal to 0.8 kg per 1 m of coal surface. In the formation of coatings, the viscosity (dynamic) of the aqueous emulsion of fat tar does not exceed 5 kPa s, and the surface tension is 10 N / m, which ensures the formation of a hardened film with a thickness of microns. Film cure

is carried out by means of a blown air stream at 20 ° C for 2 minutes. The strength of the protective coating satisfies the technological requirements for their quality. In the process

rail transportation of coal fines; the protective properties of the coating are maintained.

PRI me R 4. On the surface of the Agulak corner fractions up to 6 mm are sprayed into

for 130 s, a 10% aqueous solution of barium or calcium oxide hydrate at 20 ° C. The size of the drops does not exceed 100 microns. The consumption of the film-forming composition is taken to be optimal and equal to 1.4 kg per 1 m of coal surface. A film is formed with a penetration depth of the liquid composition into the coal layer of up to 700 microns. 3 minutes after cooling, the film cures to form a strong protective coating. The protective properties of the coating satisfy the requirements of rail transportation.

PRI me R 5. On the surface of Agulaksky angle fractions up to 6 mm is applied for 150 s sprayed 10% mixture of VAT

a synthetic fatty acid residue (CFCFA) with calcium chloride or with iron chloride. The size of the dispersible droplets is taken 100 microns, taking into account the viscosity of the mixture, the VAT residue is synthetic oily

acid is preheated to 60 ° C. After that, an aqueous solution of calcium chloride or iron chloride is introduced into it, or a mixture of CFCFA with an aqueous solution of barium or calcium hydroxide is taken

initial concentration of 10% in equal proportions. The flow rate of the mixture does not exceed 1.4 kg / m of coal surface. The viscosity of the mixture is chosen equal to kPa, and the surface tension of the droplets is 1 -2

N / m A micron coating film is formed by incorporating the liquid composition into the coal layer to a depth of 1000 microns and then cures upon cooling. The quality of the protective coating was evaluated

the integrity of the film when exposed to a blown oncoming air stream at a speed of 5-30 m / s, which corresponded to rail transportation of coal.

Example On the surface of brown coal

In the Agulakskoye deposit, fractions up to 6 mm are sprayed over 130 s in a 15% aqueous emulsion of cotton or grease tar at 60 ° C with droplet size up to 100 microns. The consumption is taken equal to 1.4 kg per 1 m of coal surface. Given viscosity, this is 1 kPa s. The formed film-forming coating is cooled in counter-current motion by a stream of air supplied at a speed of 5 m / s at 35 ° C for 3 minutes until completely cured. The protective properties of the coating satisfy technological requirements.

To clarify examples of the specific implementation of the proposed method, the composition and characteristics of the tar oil and bottoms of synthetic fatty acids are given.

Tar is a secondary product of oil refining coke plants of GOST 21046-86. The group chemical composition of the tar is shown in the table in comparison with the composition of the known coal tar pitch.

Vat residues of synthetic fatty acids and tars belong to the group of higher carboxylic acids according to GOST 23239-78. Synthetically, fatty acids are obtained by oxidation of paraffinic hydrocarbons, and fat tar is obtained by distillation of fatty acids and technical fat. There are flan and cotton grease tars. Tars of cottonseed oil (OST 18114-73, OST 18289-76, OSTTadzh.SSR 703-81) are waste products from the extraction plant (a by-product of the oil industry), they contain large amounts of aromatic hydrocarbons with high aliphaticity and functional content groups CO, COOH, COO. Gossypol resin (cotton tar) OST 18-114-73 is obtained as a bottom residue (tar) from the distillation of fatty acids isolated from cotton soap stock. It is a viscous homogeneous mass. Contains ash 1-1.2%, moisture 4%, volatiles 4%. The acid number is 50-70 mg KOH / g. Fatty acids of cotton soap stock OST 18-289-76 are obtained by decomposition of cotton soap stock with sulfuric acid. They represent a solidified solid product at an acid number of 180-195 mg KOH / g at 20 ° C, contains moisture and volatile substances of not more than 2.5%,

and

unsaponifiable substances not more than 3.0%. The pour point of fatty acids is not less than 28-32 ° C, sulfuric acid content is not allowed. Heated cured acid of oily cotton soap stock is heated in a beaker in a water bath at 50-70 ° C and mixed thoroughly with a glass rod.

The proposed method for applying a protective coating of coal has several advantages: high technological effectiveness, high-quality coating is provided, losses and entrainment of coal fines during wind erosion are eliminated. The protective properties 15 of the coating are such that they prevent freezing of the coals. This method of applying a protective coating is economically and environmentally advantageous, since it allows to eliminate dustiness and reduce coal losses in the process of transportation from one wagon to 1 ton in the process of carriage and thus save an additional amount of coal of about 16,666 tons from wind erosion.

Claims (3)

1. The method of applying a protective coating on coal, comprising spraying a liquid film-forming composition on the surface of the coal, characterized in that 30 that, in order to reduce coal losses, and as a film-forming composition, use a 10-15% aqueous emulsion of fatty tar or a mixture of bottoms of synthetic fatty acids with an aqueous solution of calcium chloride, iron, barium hydroxide or calcium, it is sprayed with droplet size of 30-100 microns at 20-60 ° C and a flow rate of 0.8-1.4 kg / m2 of coal surface. 40 2. The method according to claim 1, characterized in that the mixture of VAT residue of synthetic fatty acids with an aqueous solution of calcium chloride, iron, barium hydroxide or calcium of 10% concentration is used45 in equal proportions. 3. The method according to PP .. 1 and 2, characterized in that for spraying use a film-forming composition with a dynamic viscosity of 1-5 kPa.s and surface 50 with a tension of (1-22) -103 N / m.