WO2008148117A1 - Procédé d'augmentation de la densité apparente de minéraux - Google Patents

Procédé d'augmentation de la densité apparente de minéraux Download PDF

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Publication number
WO2008148117A1
WO2008148117A1 PCT/US2008/064926 US2008064926W WO2008148117A1 WO 2008148117 A1 WO2008148117 A1 WO 2008148117A1 US 2008064926 W US2008064926 W US 2008064926W WO 2008148117 A1 WO2008148117 A1 WO 2008148117A1
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WIPO (PCT)
Prior art keywords
slurry
mineral
kaolin clay
lbs
binder
Prior art date
Application number
PCT/US2008/064926
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English (en)
Inventor
Robert J. Pruett
Ismail Yildirim
Original Assignee
Imerys Pigments, 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 Imerys Pigments, Inc. filed Critical Imerys Pigments, Inc.
Publication of WO2008148117A1 publication Critical patent/WO2008148117A1/fr

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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
    • C04B33/00—Clay-wares
    • C04B33/02—Preparing or treating the raw materials individually or as batches
    • C04B33/04—Clay; Kaolin
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/51—Particles with a specific particle size distribution
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/11—Powder tap density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability

Definitions

  • Disclosed herein are methods for improving the bulk density of minerals, including, for example, calcined kaolin, precipitated calcium carbonate, ground calcium carbonate, and hydrous kaolin. Also disclosed herein are methods for preparing slurries, improved slurry compositions, and improved kaolin clay products.
  • inorganic materials are incorporated into the fibrous web, in an attempt to improve at least one quality of the resulting product.
  • Those materials may be called paper fillers and a number of different inorganic materials are effective for that purpose, including but not limited to titanium dioxide, which can be incorporated into the fibrous web in various forms such as anatase and rutile.
  • These inorganic fillers for example, calcined kaolin, hydrous kaolin, ground calcium carbonate, precipitated calcium carbonate, titania, and the like, may be utilized in paper applications to attain improved optical and physical properties. Typically, improvements in light scattering and gloss may be observed along with improved bulkiness.
  • inorganic fillers may improve the operating costs by decreasing the amount of paper fibers required and replacing those paper fibers with the inorganic fillers. But in recent years, considerable efforts have been expended to develop fillers that even further reduce operating costs, such as lowered transportation costs.
  • substantially anhydrous kaolin clays are substantially anhydrous kaolin clays.
  • Materials of that type are generally prepared by partially or fully calcining a crude kaolin clay, which may have been initially subjected to prior beneficiation steps in order to remove certain impurities.
  • One such beneficiation step may assist in improving brightness in the ultimate paper product.
  • Calcined kaolin clay products are normally pulverized and then air- classified after calcination to remove +325 mesh residue, for example, to conform to various specifications for intended use in paper or to remove larger abrasive particles. Such products are then sold as a finely pulverized low-bulk density powder.
  • that low-bulk density powder generally exhibits poor flow characteristics and is often difficult to handle by conventional bulk handling systems. Because of those handling difficulties, those powders (generally having a moisture content of about 5% or less by weight) are typically shipped in bulk in "sparger cars," which are bulk-hopper railroad cars fitted with special valves at the bottom, allowing water to be injected into the car upon arrival at the customer's facility. Air is then injected into the car to agitate the water and calcined kaolin clay powder mixture. As soon as possible after the injection of the water and air, the fluid suspension is pumped from the car at about 30%-35% solids into a storage tank.
  • the method comprises mixing at least one mineral with at least one aqueous solution comprising at least one binder, followed by compacting the mixture.
  • the methods comprises mixing kaolin clay with an aqueous solution comprising at least one binder, followed by compacting the kaolin clay and binder mixture.
  • the method further comprises drying the compacted mixture to reduce its moisture content.
  • the method further comprises subjecting the at least one mineral to at least one beneficiation step before mixing.
  • the method further comprises subjecting the at least one mineral to at least one classification step before mixing.
  • the at least one binder is water-soluble.
  • the method comprises contacting at least one solution with at least one mineral, followed by compacting the mineral powder in solution.
  • the method comprises contacting kaolin clay with at least one solution, followed by compacting the kaolin clay in solution.
  • the at least one solution may be chosen from at least one of the group consisting of water, at least one chemical in a solution, or at least one aqueous mineral slurry.
  • the sequence of addition may include mixing each at least one solution together to form a master solution.
  • the master solution may then be contacted with the at least one mineral. For example, a first solution and a second solution may be combined to form a single solution.
  • a first solution may be first contacted with the at least one mineral, followed by the addition of the second solution.
  • the method further comprises drying the compacted mixture to reduce its moisture content.
  • the method further comprises subjecting the at least one mineral to at least one beneficiation step before mixing with the at least one solution.
  • the method further comprises subjecting the at least one mineral to at least one classification step before mixing.
  • the contacting may comprise spraying the at least one mineral slurry onto the at least one mineral.
  • the step of contacting comprises mixing the at least one solution and the at least one mineral.
  • improved mineral products and slurries containing those products may have a bulk density ranging from about 33 lbs/ft 3 to about 90 lbs/ft 3 .
  • a slurry prepared from the mineral products may exhibit improved a high-shear viscosity ranging from about 4000 rpm to about 4500 rpm, when measured as Hercules viscosity at 18 dynes at 50% solids using an "A" bob.
  • the method comprises mixing at least one mineral with at least one aqueous solution comprising at least one binder, followed by incorporating the mixture with water and at least one dispersant, to form a slurry.
  • the at least one mineral is kaolin clay.
  • the at least one mineral is pre-compacted kaolin clay.
  • the slurry has a high-shear viscosity of more than about 1000 rpm, measured as Hercules viscosity at 18 dynes at 50% solids using an "A" bob.
  • Increasing the bulk density of a mineral may improve one or more of its physical and/or processing characteristics, such as, for example, improved flowability, decreased transportation costs, shorter slurry make-down times, reduced operating costs (e.g., less labor, less energy), improved wet-out rate, and decreased dusting.
  • the method for increasing the bulk density of at least one mineral comprises mixing at least one mineral with at least one aqueous solution, followed by compacting the mixture.
  • the method for increasing the bulk density of kaolin clay comprises mixing the kaolin clay with at least one aqueous solution followed by compacting the mixture.
  • Practicing the methods disclosed herein for increasing the bulk density of at least one mineral may produce a mineral product having bulk densities ranging from about 33 lbs/ft 3 to about 90 lbs/ft 3 .
  • the mineral product has a bulk density ranging from about 40 lbs/ft 3 to about 80 lbs/ft 3 .
  • the mineral product has a bulk density ranging from about 40 lbs/ft 3 to about 65 lbs/ft 3 .
  • the mineral product has a bulk density ranging from about 40 lbs/ft 3 to about 55 lbs/ft 3 .
  • the mineral product has a bulk density ranging from about 45 lbs/ft 3 to about 55 lbs/ft 3 .
  • bulk density which is interchangeable with “tap bulk density,” is measured as follows. A prepared 100 ml cylinder is completely filled with the at least one mineral or mineral product and tapped lightly until the level in the cylinder ceases to drop fairly rapidly. The level is then adjusted to 100 ml by adding a further amount of the at least one mineral. The cylinder and the at least one mineral it contains are then weighed. The bulk density, measured in lbs/ft 3 , is calculated according to Formula I: weight of mineral (g) / 7.48 gals.x3785 mlxl Ib.
  • the at least one mineral exhibiting increased bulk density resulting from the methods disclosed herein exhibits a moisture content of no more than about 30%. Reduced moisture content improves the at least one mineral, in part, because transportation costs decrease.
  • Moisture content as used herein, is measured as percent by weight after exposure for 40 hours at 20 0 C to an atmosphere having a relative humidity of 80%. The skilled artisan can readily adjust the methods disclosed herein to prepare at least mineral exhibiting increased bulk density exhibiting a desired moisture content level. In one embodiment, the moisture content level is about 30% or less. In another embodiment, the moisture content level is about 25% or less.
  • the moisture content level is about 20% or less. In yet another embodiment, the moisture content level is about 15% or less. In still a further embodiment, the moisture content level is about 10% or less. In yet a further embodiment, the moisture content level is about 5% or less.
  • the at least one mineral exhibiting increased bulk density may also have a particle size distribution that is finer compared to at least one mineral that has not been subjected to the methods disclosed herein.
  • Particle size distribution may be determined by measuring the sedimentation speeds of the dispersed minerals through a standard dilute aqueous suspension using a SEDIGRAPH instrument, for example, a SEDIGRAPH 5100 sold by Micromeritics Corporation of Norcross, Georgia, USA.
  • the size of a given mineral is expressed in terms of the diameter of a sphere of equivalent diameter that sediments through the suspension, i.e., an equivalent spherical diameter or esd.
  • the SEDIGRAPH instrument records the percentage by weight of particles having an esd less than a particular esd value, versus that esd value, thus allowing the calculation of a particle size distribution over a range of esd values.
  • the at least one mineral subjected to a method described herein may have a particle size distribution wherein at least about 92% by weight of the particles have an esd of less than about 2 ⁇ m. In one embodiment, at least about 93% by weight of the particles have an esd of less than about 2 ⁇ m. In another embodiment, at least about 94% by weight of the particles have an esd of less than about 2 ⁇ m.
  • At least about 95% by weight of the particles have an esd of less than about 2 ⁇ m. In yet another embodiment, at least about 96% by weight of the particles have an esd of less than about 2 ⁇ m. In yet a further embodiment, at least about 97% by weight of the particles have an esd of less than about 2 ⁇ m. In still another embodiment, at least about 98% by weight of the particles have an esd of less than about 2 ⁇ m. In still a further embodiment, at least about 99% by weight of the particles have an esd of less than about 2 ⁇ m.
  • the at least one mineral subjected to a method described herein may also have a particle size distribution wherein at least about 86% by weight of the particles have an esd of less than about 1 ⁇ m. In one embodiment, at least about 88% by weight of the particles have an esd of less than about 1 ⁇ m. In another embodiment, at least about 90% by weight of the particles have an esd of less than about 1 ⁇ m.
  • the at least one mineral subjected to a method described herein may further have a particle size distribution wherein about 25% to about 65% by weight of the particles have an esd of less than about 0.5 ⁇ m. In one embodiment, at least about 25% to about 65% by weight of the particles have an esd of less than about 0.5 ⁇ m. In another embodiment, at least about 30% to about 65% by weight of the particles have an esd of less than about 0.5 ⁇ m. In a further embodiment, at least about 35% to about 65% by weight of the particles have an esd of less than about 0.5 ⁇ m. In yet another embodiment, at least about 40% to about 65% by weight of the particles have an esd of less than about 2 ⁇ m.
  • At least about 45% to about 65% by weight of the particles have an esd of less than about 2 ⁇ m.
  • at least about 50% to about 65% by weight of the particles have an esd of less than about 2 ⁇ m.
  • at least about 55% to about 65% by weight of the particles have an esd of less than about 2 ⁇ m.
  • at least about 60% to about 65% by weight of the particles have an esd of less than about 2 ⁇ m.
  • the at least one mineral may include any appropriate mineral now known to the skilled artisan or later discovered that may benefit from an increased bulk density.
  • the at least one mineral is kaolin clay.
  • the at least one mineral is calcined kaolin clay.
  • the at least one mineral is pre-compacted kaolin clay.
  • the at least one mineral is hydrous kaolin clay.
  • the at least one mineral is kaolin clay calcined to a substantially anhydrous state.
  • the at least one mineral is calcium carbonate.
  • the at least one mineral is precipitated calcium carbonate.
  • the at least one mineral is ground calcium carbonate.
  • a substantially anhydrous calcined kaolin clays may be in any one of numerous forms.
  • the substantially anhydrous calcined kaolin clay is a fully calcined kaolin clay that has been heated above a 980 0 C exotherm.
  • the substantially anhydrous calcined kaolin clay is a metakaolin that has been heated below the 980 0 C exotherm.
  • the substantially anhydrous calcined kaolin clay is a kaolin clay heated to over about 400 0 C.
  • the at least one aqueous solution comprises at least one binder and water.
  • the at least one aqueous solution may be referred to herein as at least one binder solution.
  • the at least one binder solution facilitates contact between at least one mineral and at least one binder by providing a partially homogenous solution.
  • the at least one binder solution facilitates contact between at least one mineral and at least one binder by providing a fully homogenous solution.
  • the at least one binder of the methods disclosed herein may include any appropriate binder now known or hereafter discovered by the skilled artisan.
  • the at least one binder is water-soluble.
  • at least one water-soluble binder may be chosen from the group consisting of carboxymethyl cellulose ("CMC"), hydroxy methyl cellulose, hydroxy ethyl cellulose, polyvinyl alcohol, anionic starch, cationic starch, amphoteric starch, sodium polyacrylate, sodium carboxymethyl cellulose, and ammonium polyacrylate.
  • CMC carboxymethyl cellulose
  • the at least one binder is selected to avoid imparting discoloration of the paper product.
  • the least one binder may be chosen from sodium lignin.
  • the at least one binder is non-water-soluble.
  • the weight percentage of the at least one binder in the at least one aqueous solution may range from about 0.1 wt% to about 50 wt%. In one embodiment, the weight percentage ranges from about 1 wt% to about 40 wt%. In another embodiment, the weight percentage ranges from about 5 wt% to about 25 wt%. In a further embodiment, the weight percentage ranges from about 10 wt% to about 20 wt%. In yet another embodiment, the weight percentage ranges from about 12 wt% to about 15 wt%. In one embodiment in which the at least one binder is CMC, the weight percentage may range from about 1 wt% to about 4 wt%. In another embodiment in which the at least one binder is CMC, the weight percentage ranges from about 2 wt% to about 3 wt%.
  • the ratio of at least one binder to at least one mineral may range from about 1 pound of binder to about 3 pounds of binder per ton of mineral. In one embodiment, the ratio ranges from about 1.5 pounds binder to about 2.5 pounds binder per ton of mineral. In another embodiment, the ratio is about 2 pounds binder per ton of mineral.
  • the water of the at least one aqueous solution may be ultrapure or deionized water.
  • the water is ultrapure.
  • the water is deionized.
  • the water is from a publicly available source.
  • the at least one solution excludes at least one binder.
  • the at least one solution comprises water.
  • the at least one solution further comprises at least one chemical.
  • the at least one solution is at least one mineral slurry.
  • the chemical solution comprises a starch solution.
  • the starch is a viscous oxidized coating starch with a low degree of chlorinization.
  • the starch is a fluid oxidized coating starch with a high degree of chlorinization.
  • the starch is a viscous coating dextrin.
  • the starch is a fluid coating dextrin.
  • the mineral in the at least one mineral slurry may be kaolin clay.
  • the mineral in the at least one mineral slurry may be calcined kaolin clay.
  • the mineral in the at least one mineral slurry may be hydrous kaolin clay.
  • the mineral in the at least one mineral slurry may be substantially anhydrous kaolin clay.
  • the mineral in the at least one mineral slurry may be ground calcium carbonate.
  • the mineral in the at least one mineral slurry may be precipitated calcium carbonate.
  • the mineral in the at least one mineral slurry may be titanium dioxide.
  • the mineral in the at least one mineral slurry may be the same as the at least one mineral to which the slurry is contacted.
  • the mineral in the mineral slurry is a different type of mineral than the at least one mineral to which the slurry is contacted.
  • the concentration of the mineral in the at least one mineral slurry may range from about 20% to about 75%. In a further embodiment, the concentration of the mineral in the slurry may range from about 35% to about 65%. In yet another embodiment, the concentration of the mineral in the slurry may range from about 45% to about 55%.
  • the order of addition may be modified according to the preference of the skilled artisan.
  • a first solution of the at least two solutions may be mixed with the at least one mineral.
  • the remainder of the at least two solutions may be mixed with the at least one mineral and the first solution.
  • each solution of the at least two solutions may be combined to form a master solution and then the master solution may be mixed with the at least one mineral.
  • Numerous techniques and apparatus are currently and may hereafter be available to the skilled artisan to facilitate mixing the at least one solution and the at least one mineral.
  • a mixing method is chosen that results in at least one layer of the at least one binder coating the at least one mineral.
  • a high-shear mixer is used to mix at least a portion of the at least one solution and the at least one mineral.
  • Exemplary high-shear mixers include commercial laboratory and/or production mixers manufactured by, for example, Ross, Hobart, Henschel, Papenmeier, and Turbulizer.
  • a low-shear mixer is used to mix at least one portion of the at least one solution and the at least one mineral.
  • Exemplary low- shear mixers include screw feed augers.
  • the mixing facilitates sufficient contact between the at least one solution and the at least one mineral to increase the moisture content of the at least one mineral.
  • the at least one solution is a binder solution
  • the mixing facilitates sufficient contact between the at least one binder solution and the at least one mineral to coat at least a portion of the at least one mineral with the at least one binder.
  • additional water may be added during mixing to increase the moisture content of the at least one mineral, before it is subjected to a compacting step.
  • the pre-compacted moisture content of the at least one mineral may be about 35% or less.
  • additional water may be added to the at least one mineral before mixing to increase the moisture content of the at least one mineral, before it is subjected to a compacting step.
  • additional water may be added after mixing to increase the moisture content of the at least one mineral, before it is subjected to a compacting step.
  • another period of mixing may be used to incorporate the additional water into mixture of the at least one solution and the at least one mineral.
  • the step of mixing may comprise spraying the at least one solution onto the at least one mineral.
  • Sprays may be produced by nozzles and other atomizing systems known in the art. Suitable equipment includes, for example, pressure nozzles, two-fluid nozzles, rotary devices such as spinning cups, disks, or coned wheels, hollow cones, whirl chamber, grooved cone, solid cone, fan spray, dual orifice nozzles, poppet nozzle, spill nozzle, and sonic atomizers.
  • the diameter of the spray particles may range from about 5000 ⁇ m or less. In another embodiment, the diameter of the spray particles may range from about 3000 ⁇ m or less. In a further embodiment, the diameter of the spray particles may range from about 1500 ⁇ m or less. In yet another embodiment, the diameter of the spray particles may range from about 750 ⁇ m or less.
  • Selection of the spray producing processing equipment may impact the size of the spray particles.
  • the particle size may range from about 100 ⁇ m to about 5000 ⁇ m.
  • the spray particle size may range from about 1 ⁇ m to about 100 ⁇ m.
  • the spray is produced by bubbling a gas through the solution, then the spray particle size may range from about 20 ⁇ m to about 1000 ⁇ m.
  • the spray is produced by annular two-phase flow, then the spray particle size may range from 10 ⁇ m to about 2000 ⁇ m.
  • the methods disclosed herein further comprise compacting the mixture of the at least one solution and the least one mineral, thereby increasing the bulk density of the at least one mineral.
  • compacting the mixture comprises extruding the mixture.
  • compacting the mixture comprises granulizing the mixture.
  • compacting the mixture comprises pelletizing the mixture. Pelletizing may be carried out, for instance, in standard pelletizing equipment now known or hereafter disclosed by the skilled artisan, in which the mixture is fed in the presence of an appropriate amount of water. In one embodiment, additional water may be added to the mixture to assist in pelletizing.
  • Exemplary pelletizers include, but are not limited to, pan pelletizers, rollers, disc pelletizers, rotary drums, extruders, die compactors, pug-mill, pin mixer, and meat grinders.
  • Pelletizing equipment may be selected and/or modified, for instance, to produce a certain shape and/or design of pellet (for example, a cylinder) or pellet size.
  • the methods disclosed herein may optionally comprise drying the compacted mixture.
  • the drying removes water or other liquids from the compacted mixture, reducing the content of residual liquid to an amount suitable, for example, for transporting the mixture or for use as a paper filler.
  • Typical moisture content percentages after drying include no more than about 5%.
  • the moisture content after drying is no more than about 4%.
  • the moisture content after drying is no more than about 3%.
  • the moisture content after drying is no more than about 2%.
  • the moisture content after drying is no more than about 1 %.
  • the optional drying step may be practiced by at least one of mechanical, centrifugal, or thermal drying.
  • Mechanical drying may include applying a force to at least a portion of the compacted mixture to physically separate the water from the compacted mixture.
  • Centrifugal drying may include spinning the compacted mixture in a circular or elliptical motion at a sufficient velocity to impart centrifugal forces to the compacted mixture, removing at least a portion of the water contained therein.
  • Thermal drying may include subjecting the compacted mixture to heat sufficient to drive water out of the compacted mixture. Any appropriate thermal dryer now known or hereafter discovered may used, including but not limited to tray, screen-conveyor, tower, rotary, screw-conveyor, fluid bed, and flash dryers.
  • the compacted mixture may first be mechanically and/or centrifugally dried before undergoing thermal drying.
  • compacting the mixture may also remove a sufficient amount of water to apply thermal drying heat as the optional drying step without any need for intervening or additional mechanical or centrifugal drying.
  • compacting and optional drying may be combined.
  • compacting equipment may be selected that simultaneously removes water or other liquids from the mixture as it compacts.
  • compacting equipment may be selected that first compacts the mixture and subsequently removes water through a drying technique suitable to achieve the desired moisture content.
  • the compacting equipment may be at least partially encompassed by a heating jacket and/or include vapor-discharge connections to remove evaporated water or steam.
  • the at least one mineral may be optionally subjected to at least one beneficiation step to remove undesirable impurities.
  • Appropriate beneficiation steps are those now known or hereafter discovered by the skilled artisan.
  • the at least one mineral is subjected to the at least one beneficiation step prior to mixing with the at least one binder solution.
  • the at least one mineral is subjected to the at least one beneficiation step after mixing with the at least one binder solution but prior to compacting and/or drying.
  • the compacted and/or dried mineral/binder mixture is subjected to at least one beneficiation step.
  • the compacted mineral/binder mixture is subjected to at least one beneficiation step prior to mixing with at least one dispersant.
  • the compacted mineral/binder mixture is subjected to at least one beneficiation step prior to mixing with at least one dispersant that is water.
  • the dispersed, compacted mineral/binder mixture is subjected to at least one beneficiation step.
  • an aqueous suspension of the at least one mineral may be subjected to a froth flotation treatment operation to remove titanium-containing impurities in the froth.
  • the slurry may then be conditioned with at least one oleic acid to coat the air bubbles produced in the float cells.
  • the titania minerals adhere to the air bubbles and are floated out of the kaolin slurry.
  • An example of such a flotation process is described in U.S. Patent No. 3,450,257 to Cundy, which is incorporated by reference herein in its entirety.
  • Such a process may also result in an improved brightness in the at least one mineral, e.g., a GE brightness gain ranging from about 0.1 to about 3 units.
  • the at least one mineral may be passed through a high intensity magnetic separator to remove iron- containing impurities. Any appropriate known or hereafter discovered high intensity wet magnetic separator may be used. Such a process may also result in an improved brightness in the at least one mineral, e.g., a GE brightness gain ranging from about 0.1 to about 3.0 units.
  • the at least one mineral may be subjected to a selective flocculation process in which the impurities are flocced out of suspension while the at least one mineral remains in suspension.
  • a high molecular weight anionic polymer having a molecular weight of more than about one million is used.
  • the anionic polymer has a molecular weight of more than about 10 million.
  • the anionic polymer has a molecular weight ranging from about 10 to about 15 million.
  • the anionic polymer is a copolymer of a polyacrylamide and a polyampholyte.
  • the flocced suspension of the at least one mineral may then be ozoned, leached (bleached), and/or filtered, optionally followed by either redispersing in a makedown tank or alternatively spray dried.
  • exemplary selective flocculation processes can be found in U.S. Patent No. 4,227,920 to Chapman and Anderson, and U.S. Patent No. 5,685,900 to Yuan et al., which includes ozonation, and both of which are hereby incorporated by reference herein in their entireties.
  • the at least one mineral may be subjected to an air floatation process in which the impurities are separated from the dry mineral by use of one or more streams of air. Any appropriate air flotation process now known to the skilled artisan or hereafter discovered may be used.
  • a mineral subjected to such an at least one beneficiation step may be called an airfloat mineral; for example, a kaolin subjected to at least one air flotation process may be called an airfloat kaolin.
  • the at least one mineral is subjected to at least one beneficiation step chosen from at least one air flotation process prior to mixing with the at least one binder solution.
  • the at least one mineral is subjected to at least one beneficiation step chosen from at least one air flotation process after mixing with the at least one binder solution but prior to compacting and/or drying.
  • the compacted and/or dried mineral/binder mixture is subjected to at least one beneficiation step chosen from at least one air flotation process.
  • the compacted mineral/binder mixture is subjected to at least one beneficiation step chosen from at least one air flotation process prior to mixing with at least one dispersant.
  • the compacted mineral/binder mixture is subjected to at least one beneficiation step chosen from at least one air flotation process prior to mixing with at least one dispersant that is water.
  • the dispersed, compacted mineral/binder mixture is subjected to at least one beneficiation step chosen from at least one air flotation process.
  • Another aspect disclosed herein relates to slurries comprising the mineral products having improved bulk densities, and methods for their production.
  • the slurries described herein may comprise water, at least one mineral product having an improved bulk density, and at least one dispersant.
  • the product mixture may be incorporated into a slurry using one or more appropriate techniques known or hereafter discovered by the skilled artisan.
  • the at least one mineral product having an improved bulk density, the at least one dispersant, and water are agitated by in appropriate process to form a slurry containing the high bulk density mineral product.
  • Such slurries may exhibit finer particle size distributions relative to slurries prepared with minerals having smaller bulk densities. This finer particle size distribution indicates that higher solids percentage may be incorporated into the slurries.
  • a sufficient mass of at least one mineral having an improved bulk density may be used to prepare a slurry having a solids content of about 75% or less.
  • the slurry may have a solids content of about 60% or less.
  • the slurry may have a solids content of about 55%.
  • the slurry may have a solids content of about 50%.
  • the particle size distribution of the mineral products prepared according to the methods disclosed herein may have a d 5 o ranging from about 0.1 mm to about 5 mm. In one embodiment, the d 5 o ranges from about 0.3 mm to about 3 mm. In another embodiment, the d 5 o ranges from about 0.5 mm to about 2 mm. In yet another embodiment, the d 5 o ranges from about 0.7 mm to about 1.5 mm. As used herein, the term "d 5 o" refers to the median particle size, or the particle size value less than about which there are 50% by weight of the particles.
  • the at least one dispersant of the slurry may be any compound suitable and appropriate to disperse homogenously in water the at least one mineral product having improved bulk density.
  • Suitable embodiments of the at least one dispersant include, but are not limited to: polyelectrolytes; polyacrylates; copolymers containing polyacrylate species, such as polyacrylate salts (e.g., sodium and aluminum optionally with a group Il metal salt); sodium hexametaphosphate; non- ionic polyols; polyphosphoric acid; condensed sodium phosphate; non-ionic surfactants; and alkanolamine.
  • the at least one dispersant is tetrasodium pyrophosphate ("TSPP").
  • that least one dispersant is water.
  • the at least one dispersant is water already present in the slurry and/or the at least one mineral product.
  • the at least one dispersant is a quantity of water in addition to water that may already be present in the slurry and/or the at least one mineral product.
  • the at least one dispersant is water used to create the slurry of the at least one mineral product.
  • the slurries disclosed herein may exhibit improved pumpability compared to slurries containing mineral products without improved bulk densities. These slurries have high shear viscosities, as measured by Hercules viscosity at 18 dynes at 50% solids using an "A" bob, ranging from about 4000 rpm to about 4500 rpm. In one embodiment, the viscosity ranges from about 4100 rpm to about 4400 rpm. In another embodiment, the viscosity ranges from about 4200 rpm to about 4300 rpm.
  • the slurries disclosed herein may further comprise at least one additive to improve low-shear viscosity.
  • Low-shear viscosity is an indication of settling properties and may range from about 300 cps to about 1000 cps, as measured on a Brookfield #1 spindle at 20 rpm.
  • the low- shear viscosity ranges from about 500 cps to about 800 cps.
  • the low-shear viscosity ranges from about 600 cps to about 700 cps.
  • the at least one additive is CMC.
  • Yet another aspect disclosed herein relates to slurries comprising at least one coated mineral, and methods for their preparation.
  • the at least one mineral Before the at least one mineral is incorporated into a slurry otherwise described herein, it is first mixed with at least one aqueous solution comprising at least one binder; as such, this at least one mineral does not undergo a compacting step before becoming incorporated in the slurry and, as such, may not exhibit an improved bulk density.
  • merely mixing the at least one mineral with the at least one aqueous solution improves the high shear viscosity of slurries prepared from the at least one mineral.
  • the high shear viscosity as measured by Hercules viscosity at 18 dynes at 50% solids, may improve to at least 1000 rpm.
  • the blended mineral product is an agglomeration of at least two minerals.
  • the blended mineral product is a pellet of at least two minerals.
  • the blended mineral product is a granule of at least two minerals.
  • the blended mineral product is an extrudate of at least two minerals.
  • the bulk density of the blended mineral product may range from about 33 lbs/ft 3 to about 90 lbs/ft 3 .
  • the blended mineral product has a bulk density ranging from about 40 lbs/ft 3 to about 80 lbs/ft 3 .
  • the blended mineral product has a bulk density ranging from about 40 lbs/ft 3 to about 65 lbs/ft 3 .
  • the blended mineral product has a bulk density ranging from about 40 lbs/ft 3 to about 55 lbs/ft 3 .
  • the blended mineral product has a bulk density ranging from about 45 lbs/ft 3 to about 50 lbs/ft 3 .
  • any combination of minerals may be blended to form the blended mineral product.
  • the minerals may be selected for use as a paper coating product or as paper filler.
  • the mineral combinations may be at least two of kaolin clay, calcined kaolin clay, hydrous kaolin clay, substantially anhydrous kaolin clay, ground calcium carbonate, precipitated calcium carbonate, and titanium dioxide.
  • a 1 % w/w CMC aqueous solution was prepared.
  • the CMC solution was added to ALPHATEX kaolin clay (Imerys Pigments, Inc.; Roswell, Georgia, USA) at a ratio of 2 pounds of CMC per ton of kaolin clay.
  • the source of CMC was a sodium carboxymethyl cellulose, PE-30 EX-S (Scientific Polymers, Inc.; Atlanta, Georgia, USA).
  • the mixture of kaolin clay and aqueous CMC was passed once through an extruder having a large hole die (10 mm) and containing no cutting blades.
  • the effect of additional water on the bulk density was investigated by adding different amounts of additional water to modify the feed moisture percentage.
  • the moisture content and tap bulk density of the extrudate-the compacted kaolin clay- was measured. Some of the extrudate was dried, and its tap bulk density was also measured as provided in Table 1.
  • each sample exhibited improved tap bulk density in both the raw extrudate and the dried extrudate. Larger increases in tap bulk density were observed when additional water was added to the kaolin clay, increasing the feed moisture content. Water was added to the clay in Sample A-1 to adjust the moisture content to 8.3%; however, after the moisture content was adjusted, no additional water was added.
  • the 1 % CMC solution was added to the ALPHATEX kaolin clay in a ratio of 4 pounds of CMC to one ton of ALPHATEX kaolin clay.
  • the clay was then extruded to determine the effects of die size and cutting blades on the tap bulk density. Also, the effect of passing extrudate through the extruder was observed.
  • the extruder was a Hobart extruder having a speed of 1 ,725 rpm and a 5 HP motor (Hobart Manufacturing Co. Ltd; Model No. 4046; Windsor, Great Britain). Table 2
  • improved kaolin clay products also improves the pumpability by a factor of about 4, or the calcined kaolin slurry can be prepared at higher than 50% solids.
  • the clay was dried and then dispersed in a 50% slurry.
  • the slurry was prepared from the dried pre-compacted clay, water, and the dispersant tetrasodium pyrophosphate and mixed for 15 minutes at 7000 rpm according to a standard TAPPI slurry make- down, laboratory procedure.
  • the % solids was reduced to 50% with the addition of water.
  • the viscosity measurements were made at 50% solids.
  • the particle size distribution of the dispersed kaolin clay become finer when 6 lbs/ton of CMC was added.
  • CMC may act as a dispersant at this concentration.
  • the clay slurry was also thickest when the concentration of CMC was 6 lbs/ton.

Abstract

L'invention concerne des procédés d'amélioration de la densité apparente de minéraux. Les procédés comprennent le mélange d'au moins un minéral avec au moins une solution aqueuse comprenant au moins un liant, suivi du compactage du mélange. Les exemples de minéraux traités selon ces procédés comprennent, de manière non restrictive, le kaolin calciné, le kaolin hydraté, le carbonate de calcium précipité, et le carbonate de calcium broyé. D'autres procédés comprennent la mise en contact d'au moins un minéral avec au moins une solution, suivie du compactage du minéral et de la solution. Des densités apparentes allant d'environ 33 lbs/ft3 à environ 90 lbs/ft3 peuvent être obtenues par la mise en pratique des procédés décrits ici. L'invention concerne également des produits minéraux améliorés et des suspensions contenant ces produits minéraux.
PCT/US2008/064926 2007-05-28 2008-05-27 Procédé d'augmentation de la densité apparente de minéraux WO2008148117A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110105803A (zh) * 2019-05-17 2019-08-09 南宁聚钙新材料科技有限责任公司 一种涂料用耐碱水性钛白浆及其制备方法
CN113105759A (zh) * 2021-04-15 2021-07-13 攀枝花学院 一种二氧化钛的表面处理方法

Citations (3)

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Publication number Priority date Publication date Assignee Title
US5129953A (en) * 1990-03-26 1992-07-14 E.C.C. America, Inc. Method for improving bulk density and flowability of calcined kaolin clay products
US6238473B1 (en) * 1999-02-03 2001-05-29 Thiele Kaolin Company Kaolin clay agglomerates and process for the manufacture thereof
US20060124033A1 (en) * 2002-12-16 2006-06-15 Imerys Pigments, Inc. Fine platy kaolin composition

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5129953A (en) * 1990-03-26 1992-07-14 E.C.C. America, Inc. Method for improving bulk density and flowability of calcined kaolin clay products
US6238473B1 (en) * 1999-02-03 2001-05-29 Thiele Kaolin Company Kaolin clay agglomerates and process for the manufacture thereof
US20060124033A1 (en) * 2002-12-16 2006-06-15 Imerys Pigments, Inc. Fine platy kaolin composition

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110105803A (zh) * 2019-05-17 2019-08-09 南宁聚钙新材料科技有限责任公司 一种涂料用耐碱水性钛白浆及其制备方法
CN113105759A (zh) * 2021-04-15 2021-07-13 攀枝花学院 一种二氧化钛的表面处理方法
CN113105759B (zh) * 2021-04-15 2022-04-15 攀枝花学院 一种二氧化钛的表面处理方法

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