WO2024047519A1 - Method for dry separation - Google Patents

Method for dry separation Download PDF

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Publication number
WO2024047519A1
WO2024047519A1 PCT/IB2023/058513 IB2023058513W WO2024047519A1 WO 2024047519 A1 WO2024047519 A1 WO 2024047519A1 IB 2023058513 W IB2023058513 W IB 2023058513W WO 2024047519 A1 WO2024047519 A1 WO 2024047519A1
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WIPO (PCT)
Prior art keywords
kaolin
powder
dry separation
impurities
flash
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PCT/IB2023/058513
Other languages
French (fr)
Inventor
Johannes Rasmus JANSEN VAN RENSBURG
Original Assignee
Kaolin Group Pty Ltd
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Publication of WO2024047519A1 publication Critical patent/WO2024047519A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
    • B02C23/08—Separating or sorting of material, associated with crushing or disintegrating
    • 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
    • C09C1/40—Compounds of aluminium
    • C09C1/42—Clays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C13/00—Disintegrating by mills having rotary beater elements ; Hammer mills
    • B02C13/14—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B1/00—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids
    • F26B1/005—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids by means of disintegrating, e.g. crushing, shredding, milling the materials to be dried
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
    • F26B11/12—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in stationary drums or other mainly-closed receptacles with moving stirring devices
    • F26B11/14—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in stationary drums or other mainly-closed receptacles with moving stirring devices the stirring device moving in a horizontal or slightly-inclined plane
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/10—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers
    • F26B17/101—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis
    • F26B17/102—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis with material recirculation, classifying or disintegrating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/10—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers
    • F26B17/101—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis
    • F26B17/103—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis with specific material feeding arrangements, e.g. combined with disintegrating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/10—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers
    • F26B17/101—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis
    • F26B17/104—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure having the shape of one or a plurality of shafts or ducts, e.g. with substantially straight and vertical axis with fixed or moving internal bodies for defining or changing the course of the entrained material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
    • F26B3/092—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed agitating the fluidised bed, e.g. by vibrating or pulsating
    • F26B3/0923—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed agitating the fluidised bed, e.g. by vibrating or pulsating by mechanical means, e.g. vibrated plate, stirrer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
    • F26B3/092—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed agitating the fluidised bed, e.g. by vibrating or pulsating
    • F26B3/0926—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed agitating the fluidised bed, e.g. by vibrating or pulsating by pneumatic means, e.g. spouted beds
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
    • F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
    • F26B3/347—Electromagnetic heating, e.g. induction heating or heating using microwave energy

Abstract

The invention discloses a method for dry separation for removing impurities in kaolin deposits, which includes the steps: of crushing and de-gritting raw Kaolin; of pre-drying the Kaolin to remove moisture to below 8%; of pulverizing the Kaolin to a uniform powder, de-gritted and screened for any small stones and impurities to form a Kaolin powder; of spin-flash drying the Kaolin powder; of separating quartz and other heavier clays from the Kaolin powder; of primary dry separation for removing impurities from the flash drier; and of secondary dry separation for further removing impurities from the Kaolin powder on a vibrating screen.

Description

METHOD FOR DRY SEPARATION
FIELD OF INVENTION
The present invention relates to a method for dry separation.
More particularly, the present invention relates to a method for dry separation of Kaolin clay.
BACKGROUND TO INVENTION
Kaolin clay, also called China clay, is a soft white clay that is an essential ingredient in the manufacture of China and porcelain and is widely used in the making of paper, rubber, paint, and many other products. Kaolin is named after the hill in China (Kao- ling) from which it was mined for centuries. Samples of kaolin were first sent to Europe by a French Jesuit missionary around 1700 as examples of the materials used by the Chinese in the manufacture of porcelain.
In its natural state kaolin is a white, soft powder consisting principally of the mineral kaolinite, which, under the electron microscope, is seen to consist of roughly hexagonal, platy crystals ranging in size from about 0.1 micrometer to 10 micrometers or even larger. These crystals may take vermicular and book like forms, and occasionally macroscopic forms approaching millimeter size are found. Kaolin as found in nature usually contains varying amounts of other minerals such as muscovite, quartz, feldspar, and anatase. In addition, crude kaolin is frequently stained yellow by iron hydroxide pigments. It is often necessary to bleach the clay chemically to remove the iron pigment and to wash it with water to remove the other minerals in order to prepare kaolin for commercial use.
When kaolin is mixed with water in the range of 20 to 35 percent, it becomes plastic (i.e., it can be molded under pressure), and the shape is retained after the pressure is removed. With larger percentages of water, the kaolin forms a slurry, or watery suspension. The amount of water required to achieve plasticity and viscosity varies with the size of the kaolinite particles and also with certain chemicals that may be present in the kaolin. Kaolin has been mined in France, England, Saxony (Germany), Bohemia (Czech Republic), and in the United States, where the best-known deposits are in the southeastern states.
Approximately 40 percent of the kaolin produced is used in the filling and coating of paper. In filling, the kaolin is mixed with the cellulose fiber and forms an integral part of the paper sheet to give it body, colour, opacity, and printability. In coating, the kaolin is plated along with an adhesive on the paper’s surface to give gloss, colour, high opacity, and greater printability. Kaolin used for coating is prepared so that most of the kaolinite particles are less than two micrometers in diameter.
Kaolin is used extensively in the ceramic industry, where its high fusion temperature and white burning characteristics makes it particularly suitable for the manufacture of whiteware (China), porcelain, and refractories. The absence of any iron, alkalis, or alkaline earths in the molecular structure of kaolinite confers upon it these desirable ceramic properties. In the manufacture of whiteware the kaolin is usually mixed with approximately equal amounts of silica and feldspar and a somewhat smaller amount of a plastic light-burning clay known as ball clay. These components are necessary to obtain the proper properties of plasticity, shrinkage, vitrification, etc., for forming and firing the ware. Kaolin is generally used alone in the manufacture of refractories.
Substantial tonnages of kaolin are used for filling rubber to improve its mechanical strength and resistance to abrasion. For this purpose, the clay used must be extremely pure kaolinite and exceedingly fine grained. Kaolin is also used as an extender and flattening agent in paints. It is frequently used in adhesives for paper to control the penetration into the paper. Kaolin is an important ingredient in ink, organic plastics, some cosmetics, and many other products where it’s exceptionally fine particle size, whiteness, chemical inertness, and absorption properties give it particular value.
Kaolin clay is an abundant material on earth, occurring on every continent. As Kaolin was formed through weathered Feldspar and other granite rocks, Kaolin deposits usually contain both Kaolinite and fine Quartz, as well as other clays, such as Mica, Muscovite, Illite, etc., and other minor impurities such as Ilmenite and Iron.
For the highest value beneficiation of Kaolin, usually processes of wet separation are utilized, to obtain the highest purity Kaolinite. However, wet separation adds considerable cost, as well as a high environmental footprint to the final Kaolin. For applications of Kaolin, where the price pressure on the kaolin clay is demanding, wet separation is not commercially feasible.
It is an object of the invention to suggest a novel method for dry separation for overcoming the above obstacles. SUMMARY OF INVENTION
According to the invention, a method for dry separation adapted for substantially removing impurities in kaolin deposits.
The method may include the steps:
(a) of crushing and de-gritting raw Kaolin;
(b) of pre-drying the Kaolin to remove moisture to below 8%;
(c) of pulverizing the Kaolin to a uniform powder, de-gritted and screened for any small stones and impurities to form a Kaolin powder;
(d) of spin-flash drying the Kaolin powder;
(e) of separating quartz and other heavier clays from the Kaolin powder;
(f) of primary dry separation for removing impurities from the flash drier;
(g) of secondary dry separation for further removing impurities from the Kaolin powder on a vibrating screen.
The step of pre-drying may be performed naturally and/or in a pre-dryer apparatus.
The Kaolin powder may have a diameter of less than 2mm.
The step of pulverizing excludes milling the Kaolin but may include spinning and bouncing the Kaolin against wear plates, in a high velocity environment, where kaolin granules get shattered and reduced to powder by friction between such granules and powder, thus breaking down clay and contained impurities into smaller inherently present particle sizes. The step of spin-flash drying includes introducing the Kaolin powder into a vertical spinflash dryer wherein the powder is falling onto a stack of slowly spinning blades, with hot air (150-200°C) introduced to the bottom of the flash spin dryer, creating further turbulence for the kaolin particles to rub against one another, as well as to remove the remaining contained moisture.
The action in the flash spin dryer may thus further micronize the kaolin powder into smaller inherent particle sizes, as well as to create a hot air updraft.
The step of primary dry separation for separating quartz and other heavier clays may occur inside the flash dryer due to
(a) the kaolin particles are able to reduce to a much smaller particle size than the quartz and other heavier clays (such as Mica and other ball clays etc.);
(b) the difference in particle shapes (kaolinite has platelet shape particles, versus quartz being either round or needle shaped).
This may allow the kaolinite particles to rise easily in the hot air updraft, whereas heavier particles of quartz and other impurities, which also do not have the benefit of rising easily due to the difference in particle shape, fall to the bottom of the flash drier body.
The step of primary separation of removing impurities from the flash drier may include sweeping out impurities settling at the bottom of the flash drier in a circular fashion, due to the cone-shaped bottom of the flash drier and drop out through openings to be taken out of the airstream with the use of rotary valves. The step of primary separation may be increased in efficiency by introducing radiation causing heat rays, in the form of either microwaves, or infrared into the flash drier chamber.
Heat rays may cause inherent thermal shock to the small kaolin granules and thus allow for these small granules to split the contained quartz, kaolinite, and other impurities apart.
The step of secondary dry separation may be applied after the step of primary dry separation in which the fine, dry separated kaolin powder is put onto a vibrating screen.
Infrared lights or microwave rays may be positioned above the screen to heat and apply energy to the kaolin powder.
This may result in fluidizing the kaolin powder on the screen and inflicting further thermal shock on it, allowing for further separation of kaolinite, quartz, and other impurities, which then can be screened of through the vibrating screen.
The step of secondary dry separation may be utilized as a standalone dry separation method for some materials, after these have been dried and pulverized.
The step of secondary dry separation may include the presence of microwave energy or infrared lights, to fluidize the powder and allow separation of the different materials through a fine mesh.
The mesh size may need to be determined by data from particle analysis of the contained minerals and impurities. The dry separation method may also be applied for other mineral groups as well, such as bentonites etc.
BRIEF DESCRIPTION OF DRAWING
The invention will now be described by way of example with reference to the accompanying schematic drawing.
In the drawings there is shown a dry separation arrangement for a method for dry separation adapted for substantially removing impurities in kaolin deposits according to the invention.
DETAILED DESCRIPTION OF DRAWING
Referring to the drawing, there is shown a dry separation arrangement for a method for dry separation adapted for substantially removing impurities in kaolin deposits in accordance with the invention.
The arrangement includes the following process steps:
1 : Dried and pulverized material enters a flash dryer;
2: Hot air 150-200°C entering at bottom of flash dryer in a cyclonic fashion ;
3: Powder spinning inside flash dryer on stack of rotating blades;
4: Impurities and heavier materials fall to the bottom of flash drier and are discharged through rotary valves;
5: Hot air updraft; and 6: Introduction of additional microwave or infrared heat into chamber.
The method for dry separation adapted for substantially removing impurities in kaolin deposits in accordance with the invention includes the following steps:
(a) Raw Kaolin must be crushed and de-gritted
(b) Kaolin to be pre-dried (naturally or in a pre-dryer) to remove moisture to below 8%
(c) Kaolin then gets pulverized, to a uniform powder, de-gritted and screened for any small stones and impurities >2mm.
(d) It is important to avoid milling the kaolin, but utilizing a pulverizing method, where kaolin is spun and bounced against wear plates, in a high velocity environment, where kaolin granules get shattered and reduced to powder by friction between such granules and powder, thus breaking down clay and contained impurities into smaller inherently present particle sizes.
(e) The kaolin powder is then introduced into a vertical spin-flash dryer, where the powder is falling onto a stack of slowly spinning blades, with hot air (150- 200°C) introduced to the bottom of the flash spin dryer, creating further turbulence for the kaolin particles to rub against one another, as well as to remove the remaining contained moisture. The action in the flash spin dryer thus further micronizes the kaolin powder into smaller inherent particle sizes, as well as to create a hot air updraft.
(f) The Primary stage of dry separation occurs in this stadium inside the flash dryer, through the fact that the kaolin particles are able to reduce to a much smaller particle size than the quartz and other heavier clays (such as Mica and other ball clays etc.), and secondly, through the difference in particle shapes (kaolinite has platelet shape particles, versus quartz being either round or needle shaped). This allows the kaolinite particles to rise easily in the hot air updraft, whereas heavier particles of quartz and other impurities, which also do not have the benefit of rising easily due to the difference in particle shape, to fall to the bottom of the flash drier body.
(g) The impurities settling at the bottom of the flash drier are swept in a circular fashion, due to the cone-shaped bottom of the flash drier and drop out through openings to be taken out of the airstream with the use of rotary valves.
(h) The process of Primary separation can be increased in efficiency by introducing radiation causing heat rays, in the form of either microwaves, or infrared into the flash drier chamber. Heat rays cause inherent thermal shock to the small kaolin granules and thus allows for these small granules to split the contained quartz, kaolinite, and other impurities apart.
(i) A Secondary stage of dry separation can now be applied after the Primary stage, whereas the fine, dry separated kaolin powder is put onto a vibrating screen. Infrared lights or microwave rays are positioned above the screen to heat and apply energy to the kaolin powder. This results in fluidizing the kaolin powder on the screen and inflicting further thermal shock on it, allowing for further separation of kaolinite, quartz, and other impurities, which then can be screened of through the vibrating screen. (j) The secondary stage of dry separation may be utilized as a standalone dry separation method for some materials, after these have been dried and pulverized. The importance is the presence of microwave energy or infrared lights, to fluidize the powder and allow separation of the different materials through a fine mesh. The mesh size needs to be determined by data from particle analysis of the contained minerals and impurities.
(k) This dry separation process can be applied for other mineral groups as well, such as bentonites etc.
The method for dry separation according to the invention covers a process of dry separation, whereas the impurities in the kaolin deposit can be removed substantially, making it possible to beneficiate the final kaolin to a level, where broad industrial applications are possible, without adding significant cost or environmental footprint.
The method for dry separation according to the invention thus enables production of a relatively low-grade kaolin affordable for the construction industry.

Claims

PATENT CLAIMS
1 . A method for dry separation for removing impurities in kaolin deposits, which includes the steps:
(a) of crushing and de-gritting raw Kaolin;
(b) of pre-drying the Kaolin to remove moisture to below 8%;
(c) of pulverizing the Kaolin to a uniform powder, de-gritted and screened for any small stones and impurities to form a Kaolin powder;
(d) of spin-flash drying the Kaolin powder;
(e) of separating quartz and other heavier clays from the Kaolin powder;
(f) of primary dry separation for removing impurities from the flash drier; and
(g) of secondary dry separation for further removing impurities from the Kaolin powder on a vibrating screen.
2. A method as claimed in claim 1 , in which the step of pre-drying is performed naturally and/or in a pre-dryer apparatus.
3. A method as claimed in claim 1 or claim 2, in which the Kaolin powder has a diameter of less than 2mm.
4. A method as claimed in any one of the preceding claims, in which the step of pulverizing excludes milling the Kaolin but includes spinning and bouncing the Kaolin against wear plates, in a high velocity environment, where kaolin granules get shattered and reduced to powder by friction between such granules and powder, thus breaking down clay and contained impurities into smaller inherently present particle sizes. A method as claimed in any one of the preceding claims, in which the step of spin-flash drying includes introducing the Kaolin powder into a vertical spin-flash dryer wherein the powder is falling onto a stack of slowly spinning blades, with hot air (150-200°C) introduced to the bottom of the flash spin dryer, creating further turbulence for the kaolin particles to rub against one another, as well as to remove the remaining contained moisture. A method as claimed in any one of the preceding claims, in which the action in the flash spin dryer thus further micronizes the kaolin powder into smaller inherent particle sizes, as well as to create a hot air updraft. A method as claimed in any one of the preceding claims, in which the step of primary dry separation for separating quartz and other heavier clays occurs inside the flash dryer due to the kaolin particles are able to reduce to a much smaller particle size than the quartz and other heavier clays (such as Mica and other ball clays etc.) and/or the difference in particle shapes (kaolinite has platelet shape particles, versus quartz being either round or needle shaped). A method as claimed in claim 8, which is adapted to allow the kaolinite particles to rise easily in the hot air updraft, whereas heavier particles of quartz and other impurities, which also do not have the benefit of rising easily due to the difference in particle shape, fall to the bottom of the flash drier body. A method as claimed in any one of the preceding claims, in which the step of primary separation of removing impurities from the flash drier includes sweeping out impurities settling at the bottom of the flash drier in a circular fashion, due to the cone-shaped bottom of the flash drier and drop out through openings to be taken out of the airstream with the use of rotary valves. 0. A method as claimed in any one of the preceding claims, in which the step of primary separation is increased in efficiency by introducing radiation into the flash drier chamber. 1 . A method as claimed in claim 10, in which the radiation causes heat rays in the form of either microwaves or infrared. 2. A method as claimed in any one of the preceding claims, in which heat rays cause inherent thermal shock to the small kaolin granules and thus allow for these small granules to split the contained quartz, kaolinite, and other impurities apart. 3. A method as claimed in any one of the preceding claims, in which the step of secondary dry separation is applied after the step of primary dry separation in which the fine, dry separated kaolin powder is put onto a vibrating screen.4. A method as claimed in claim 13, in which infrared lights or microwave rays are positioned above the screen to heat and apply energy to the kaolin powder.5. A method as claimed in claim 14, which results in fluidizing the kaolin powder on the screen and inflicting further thermal shock to it, allowing for further separation of kaolinite, quartz, and other impurities, which then can be screened of through the vibrating screen. 6. A method as claimed in any one of the preceding claims, in which the step of secondary dry separation is utilized as a standalone dry separation method for some materials, after these have been dried and pulverized. A method as claimed in any one of the preceding claims, in which the step of secondary dry separation includes the presence of microwave energy or infrared lights, to fluidize the powder and allow separation of the different materials through a fine mesh. A method as claimed in claim 17, in which the mesh size is determined by data from particle analysis of the contained minerals and impurities. A method as claimed in any of the preceding claims, which is adapted to be applied for other mineral groups as well, such as bentonites. A method for dry separation for removing impurities in kaolin deposits substantially as hereinbefore described with reference to the accompanying drawing. A method for dry separation for removing impurities substantially as hereinbefore described with reference to the accompanying drawing. A method for dry separation substantially as hereinbefore described with reference to the accompanying drawing.
PCT/IB2023/058513 2022-08-29 2023-08-29 Method for dry separation WO2024047519A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120039830A1 (en) * 2009-03-18 2012-02-16 Takuma Kurahashi Process for producing powdery composition and powdery cosmetic
CN210675549U (en) * 2019-12-17 2020-06-05 福建科福材料有限公司 Centrifugal spin-drying device for low-resistivity porcelain clay
CN211303714U (en) * 2019-12-19 2020-08-21 福建省德化上古陶瓷有限公司 Kaolin screening device for ceramic production

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120039830A1 (en) * 2009-03-18 2012-02-16 Takuma Kurahashi Process for producing powdery composition and powdery cosmetic
CN210675549U (en) * 2019-12-17 2020-06-05 福建科福材料有限公司 Centrifugal spin-drying device for low-resistivity porcelain clay
CN211303714U (en) * 2019-12-19 2020-08-21 福建省德化上古陶瓷有限公司 Kaolin screening device for ceramic production

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