Abstract: A method which enables economical and highly effective preparation of refined kaolin clay products having preselected particle size distributions and brightnesses, by means of separate, efficient and economical processing of at least two crude components. A fine particle size kaolin crude having a PSD such that at least 85% by weight of the particles are of less than 2 micrometers ESD is wet beneficiated to provide a first product component having a PSD of at least 95% by weight less than 2 micrometers and a brightness of at least 89 on the G.E. scale. This wet beneficiation is conducted without use of a froth flotation step. A coarse particle size kaolin crude having a PSD such that less than 85% by weight of particles are of less than 2 micrometers ESD, is separately wet beneficiated to produce a second product component having a PSD of no more than 85% by weight less than 2 micrometers and a brightness of at least 89 on the G.E. scale.

Abstract: A method for producing calcined kaolin pigments of high opacifying properties and low abrasion. A kaolin crude is selected having a G.E. brightness in the range of 70 to 80, a titania content of 2.0 to 3.0% by weight, less than 2% iron expressed as Fe.sub.2 O.sub.3, and a particle size distribution such that at least 88% by weight of the particles of said crude are of less than 2 .mu.m E.S.D.. The crude is blunged with water, and the resultant slurry degritted to form an aqueous slurry having at least 65% by weight solids. The slurry is centrifuged and a fraction recovered having over 65% solids, and in which at least 92% by weight of the particles are of less than 2 .mu.m. The recovered fraction is dried to less than 1% moisture, and pulverized to break up agglomerates. The pulverized fraction is then calcined by heating same to 1450.degree. to 1600.degree. F. after which the calcined kaolin is milled to yield a product having a G.E. brightness of 79 to 81 and an Einleiner abrasion of not mere than 2.

Abstract: Calcined kaolin clay is pelletized in a pelletizer by a process wherein the calcined clay has ammonia added to it, suitably in relatively small amounts such as less than 1% by weight. The pelletized clay is preferably coated with a binder to improve its flowability.

Abstract: A method for beneficiating a kaolin clay which includes quantities of smectite contaminants to reduce the low and high shear viscosities of high solids aqueous slurries of the kaolin. The smectite is converted into a pillared clay by intercalating it with a polymeric cationic hydroxy metal complex wherein the metal is ferromagnetic or diamagnetic. The kaolin and pillared smectite is then subjected as an aqueous slurry to high intensity magnetic separation, to separate the pillared smectite, and the beneficiated kaolin is recovered as product.

Abstract: A process for producing rhombic or barrel shaped precipitated calcium carbonate. Quicklime is slaked in an aqueous solution containing about 0.1% to about 2% by weight of a sugar, based upon the weight of the CaCO.sub.3 to be produced. Carbon dioxide is added to the slaked lime slurry at a preferred temperature of about 50.degree. F.-70.degree. F. until the pH drops from about 11-12 to about 7-8.

Abstract: A method for producing a high solids aqueous slurry of particulate calcium carbonate having highly stable aging characteristics, comprising dispersing in water at at least 70% by weight solids, a finely divided particulate calcium carbonate, utilizing as a dispersing agent from 20 to 34 lbs/ton of dry mineral (expressed as 40% actives), of a copolymer of acrylic acid and a sulfonated vinyl monomer, which is converted to the salt form by from about 30 to 50% of its carboxylic acid sites being neutralized with a polyvalent cation, and substantially the balance of said carboxylic sites being neutralized with a monovalent cation.

Abstract: Improvements are disclosed in apparatus for air classifying mineral particles by size. The apparatus is of the type including a vertically oriented flow channel for carrying an upwardly directed air flow stream in which the particles are dispersed and a cylindrical air classifier mounted in the flow channel. The classifier has a cage which is rotatable about a vertical axis and is laterally open to the flow channel. A plurality of spaced vertical rejector blades are mounted about the lateral periphery, and the cage is closed at its lower end by a support plate. An outlet is connected to the classifier interior for withdrawing particles passing radially through the blades for collection; and air drawing device is connected to the outlet for drawing the air stream and particles into the classifier and establishing an upward flow of air and dispersed particles within channel.

Abstract: An improved process for producing a aggregated kaolin pigment having desired physical and optical characteristics when used as a coating, filler or pigment in paper. The aggregated pigment is produced by contacting a substantially dry fine particle size kaolin with a previously hydrolyzed organic silicon compound, such as hydrolyzed tetraethoxysilane, and then recovering the aggregated kaolin pigment.

Abstract: A method for preparing a calcined kaolin clay powder having good high shear rheology in high solids aqueous slurries. A kaolin clay powder of fine particle size is calcined at a sufficient temperature and for a sufficient period to destroy the crystallinity thereof; and the calcined product is dry milled in a media mill, using a work input of from 100 to 160 hp-hr/ton of dry clay.

Abstract: A process for forming chemically aggregated composite porous bulking pigments for use in paper filling and coating formulations. An aqueous slurry is formed of feed mineral particles selected from one or more members of the group consisting of kaolin, calcium carbonate, titanium dioxide, gypsum, and mica. A high molecular weight carboxyl-containing polymer or copolymer is added to the slurry to flocculate the mineral particles. An excess of calcium ion is added to the flocced slurry to precipitate the calcium salt of the carboxyl-containing polymer in situ on the feed mineral flocs, and thereby form aggregates of feed mineral particles interconnected by the calcium salt and having a bulk, porous, floc structure. Gaseous carbon dioxide is added to the slurry, and reacts with remaining calcium ion to precipitate calcium carbonate onto the polymeric carboxyl calcium salt. This forms additional light scattering voids or pores and strengthens the connections among the flocced feed particles.

Abstract: An improved process for producing a aggregated kaolin pigment having desired physical and optical characteristics when used as a coating, filler or pigment in paper. The aggregated pigment is produced by mixing an aqueous slurry of a fine particle kaolin with a previously hydrolyzed organic silicon compound, such as hydrolyzed tetraethoxysilane, and then spray drying the mixture to form a dry, chemically aggregated kaolin pigment.

Abstract: A process for producing a high solids aqueous slurry of a beneficiated kaolin. An impure crude kaolin clay is initially subjected to wet processing including a size classification step, to recover a beneficiated fine particle size kaolin fraction which is formed into a dilute aqueous slurry of deflocculated kaolin particles. The dilute slurry is filtered by flowing it generally parallel to and in contact with the surface of a microporous barrier while maintaining a pressure drop across the barrier in a direction transverse to the slurry flow. A gel permeation layer is thereby formed of kaolin overlying the surface of the microporous barrier. The gel permeation layer and underlaying surface are substantially impervious to the passage of clay solids while being pervious to the passage of water molecules, ions and dissolved salts; whereby water molecules, ions and dissolved salts are caused to pass through the barrier, thereby increasing the concentration of the solids in the kaolin slurry.

Abstract: A process for producing a high brightness, high solids kaolin clay aqueous slurry. An aqueous low solids suspension of crude kaolin clay is degritted, and subjected to a particle size classification. The aqueous suspension of the fine particle fraction is acidified to a pH of 5.0 or lower to produce an acid flocculated suspension which is treated with a bleaching agent to reduce ferric ion impurities to ferrous ion impurities. A ferrous ion chelating agent is added to the bleached acid flocculated suspension after which an alkaline agent is added to raise the pH to a level greater than 5.0 to form a dispersed aqueous suspension of the beneficiated kaolin. The dispersed suspension is then subjected to membrane filtration to partially dewater same, and additional water is thermally evaporated from the partially dewatered dispersed kaolin suspension to produce the high solids product suspension.

Abstract: An improvement is disclosed which is applicable to the method for filtering an aqueous mineral slurry by flowing the slurry through a ceramic filter plate which is characterized by a porous support layer and an overlying porous filtration layer, the pore sizes in said filtration layer being in the range of from about 1 to 3 .mu.m, and the flow through the filter plate being from the filter layer side toward the base layer, and being effected by establishing a fluid pressure differential across the said filter plate by applying suction to the the porous support layer. The improvement facilitates effective discharge of the filter cake from the plate which accumulates upon the porous filtration layer. According to such improvement the suction is extinguished and the support layer side of the plate is subjected to one ore more positive water pressure pulses to effect a transient reverse flow through the plate.

Abstract: An apparatus for filtering slurries of minerals or other fine particles is disclosed. The apparatus includes a ceramic filter plate and a fluid flow device for drawing a partial vacuum across said filter plate and to supply a pulsed liquid to the filtrate side of said filter plate. The apparatus also includes an oscillating device that facilitates removal of cake which accumulates on the filter plate when sued simultaneously with or successively with said pulsed liquid.

Abstract: A high opacity, high light scattering filler pigment for use in wood-containing paper manufacture, comprising by weight 25 to 50% of a fine particle size hydrous kaolin which has been defined as to have particle size distribution such that less than 20% by weight are of less than 0.3 .mu.m E.S.D. and substantially the balance being a fine particle size calcined kaolin.