Abstract: A method of enhancing the brightness and increasing the yield of a kaolin clay by optimizing the removal of the titania and mica impurities in the clay and the amount of clay remaining in the slurry is disclosed. The method is a selective flocculation process wherein the clay is blunged, dispersed, and conditioned before flocculation. In the flocculation step, a high molecular weight anionic polymer and a low molecular weight anionic polymer, such as sodium polyacrylate, are added to the slurry after the conditioning process, whereby the titania-mica enriched flocs are separated from the suspension which is enriched with kaolin. This final kaolin product has titania levels ranging from 0.1% to 0.5%, a reduced mica level, a high usable product yield, and a brightness greater than 89.5 and at least 91.5.

Abstract: Improved methods of screening particulate matter are disclosed. For example, aqueous mineral slurries containing at least 10 weight percent of finely divided mineral solids are mechanically size separated using vibratory screening and a self propelled recirculative rotating spray bar, prior to, and subsequent to various processing steps. The employment of the spray bar improves the screening process by preventing blinding of the screen, as well as increasing throughput. As a result this invention reduces screen residues and/or increases production rates significantly.

Abstract: A method for producing a high solids slurry of an acid-resistant precipitated calcium carbonate for shipping purposes is disclosed. A low solids of about 18 wt. % to 20 wt. % solids slurry is treated with a chemical additive, such as sodium aluminate, in order to impart acid resistance to the calcium carbonate, and is dewatered to form an intermediate solids slurry of about 44 wt. %. This intermediate solids slurry is then diluted with a fraction of the low solids slurry which was treated with the chemical additive, in order to bring the intermediate slurry to a final high solids slurry of about 35 wt. %. Acid is added to the final product slurry in order to reduce the pH of the final slurry to within a buffering range of about 7.0 to 6.5. The final product slurry of about 35 wt. % comprises an acid-resistant calcium carbonate composition with a pH of about 7.0 which can be shipped for ultimate use when making paper under neutral pH conditions.

Abstract: An improved method for dry milling calcined kaolin clays involves use of an effective amount of an ammonium polyacrylate dry grinding aid which is applied to a calcined kaolin clay product prior to dry milling. This improves flowability of the product through the mill, resulting in an increase in the grinding efficiency and, therefore, an increase in the production rate of the mill. The final product displays an increase in Hercules high shear viscosity, and therefore, an increase in the rheology in very high solids aqueous slurries, which is particularly useful in the coating of paper and paperboard products.

Abstract: A thermoplastic granule containing a high proportion of a particulate carbonate filler in a thermoplastic binder, for blending with an end product thermoplastic in which the carbonate filler is to be dispersed. The granule comprises at least 85% by weight of a particulate carbonate which is coated with one or more fatty acids having a carbon chain length of from 12 to 20 carbon atoms. The balance of the granule by weight comprises a thermoplastic polymeric binder which is solid at ambient temperature and is compatible with the end product thermoplastic in which the carbonate filler is to be dispersed. The polymeric binder is an amorphous polyolefins and/or a highly branched polyethylene wax. The PSD of the carbonate is selected to maximize packing.

Abstract: An improvement is disclosed applicable to the method for producing a calcined kaolin by the steps of wet beneficiating a crude kaolin to form a slurry of the beneficiated kaolin; dewatering the slurry to form a substantially dry calciner feed; and calcining the feed at a temperature of at least 1450.degree. F. by passing a stream of hot gases through a calciner in which the kaolin feed is resident, whereby an exhaust stream of hot gases is generated which entrains quantities of partially calcined and hydrous kaolin pigment fines. The improvement, enabling useful application of the kaolin pigment fines, comprises recovering the kaolin pigment fines from the exhaust stream for use in papermaking. The fines can be recovered at a wet scrubber, and after being partially dewatered, shipped directly as a product slurry to the paper maker.

Abstract: An improved form of calcium carbonate which is acid tolerant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid tolerant calcium carbonate are provided. This acid tolerant calcium carbonate comprises a mixture of calcium carbonate with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of sodium aluminate together with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of one or more weak acids.

Abstract: A method for beneficiating a low brightness fine particle size discolored kaolin crude to produce a high brightness coating clay. By combining the two beneficiating techniques of selective flocculation and ozonation, a synergistic phenomena occurs and a clay product of superior brightness and whiteness can be obtained from fine discolored clays that cannot be achieved by beneficiation with either process singularly. By passing the flocced clay through ozonation, the flocculant polymer left in the clay can be completely destroyed.

Abstract: A process for recovering inorganic material from an effluent suspension produced in the treatment of waste paper. The effluent suspension, in the form of an aqueous suspension containing at least 2% by weight of dry solids, is contacted with an oxygen-containing gas at an elevated temperature, and at an elevated pressure sufficient to keep the water component of the sludge in the liquid phase, for a time sufficient to effect substantially complete oxidation of the organic material in the suspension. The resulting product is dewatered and then resuspended in water, whereafter there is separated from the suspension water containing fine carbon particles in suspension to leave the desired inorganic material.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid resistant calcium carbonate are provided. This acid resistant calcium carbonate comprises a mixture of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of sodium carbonate, together with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of weak acids in admixture with the calcium carbonate.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid resistant calcium carbonate are provided. This acid resistant calcium carbonate comprises a mixture of at least about 0.5 to about 10 percent of an aluminum salt, based on the dry weight of calcium carbonate, and calcium carbonate. Preferred aluminum salts are aluminum sulfate, aluminum chloride, and polyaluminum chloride.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid resistant calcium carbonate are provided. This acid resistant calcium carbonate comprises a mixture of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of an aluminum or magnesium hydroxide, together with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a mixture of weak acids.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid resistant calcium carbonate is provided. This acid resistant calcium carbonate comprises a mixture of at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a weak base together with at least about 0.1 percent, based on the dry weight of the calcium carbonate, of a weak acid.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid-resistant calcium carbonate is provided. This acid-resistant calcium carbonate comprises calcium carbonate in admixture with at least about 0.5 to about 10 percent, based on the dry weight of the calcium carbonate, of a cationic salt, together with at least about 0.5 to about 10 percent, based on the dry weight of the calcium carbonate, of an anionic salt.

Abstract: An apparatus is disclosed for filtering slurries of minerals or other fine particles. The apparatus includes a filter plate having an interior porous support layer and a microporous metal filtration layer overlying the support layer, the pore sizes in the filtration layer preferably being in the range of from about 0.2 to 3 microns. The side of the filtration layer non-adjacent the support layer constitutes a filter surface for the mineral.

Abstract: A method for filtering an aqueous mineral slurry and collection of the mineral as product. The slurry is flowed through a filter plate of the type characterized by a porous support layer and an overlying microporous metal filtration layer, with flow through the filter plate during filtration being from the filtration layer side toward the base layer and being effected by establishing a fluid pressure differential across the filter plate. The filtration layer preferably comprises a sintered metal, with a relatively narrow pore size distribution, i.e. one wherein substantially all of the pores are less than 5 .mu.m.

Abstract: An improved form of calcium carbonate which is acid resistant to enable its use as a filler material in the making of neutral to weakly acid paper, and a process for producing this acid-resistant calcium carbonate is provided. This acid-resistant calcium carbonate comprises calcium carbonate in admixture with at least about 0.5 to about 10 percent, based on the dry weight of the calcium carbonate, of a cationic salt, together with at least about 0.5 to about 10 percent, based on the dry weight of the calcium carbonate, of an anionic salt.

Abstract: A process for preparing a high brightness, low abrasion calcined kaolin. A cretaceous crude is wet beneficiated by subjecting same as an aqueous slurry to degritting, classification, magnetic separation, and scrub grinding. The slurry from the foregoing is diluted to less than 15% solids and subjected while well dispersed to a separation in a centrifuge to yield an underflow and an overflow fine fraction having less than 5% solids and a P.S.D. such that at least 85% by weight are of <0.5 .mu.m E.S.D. and at least 30% by weight are of <0.25 .mu.m E.S.D. The overflow fine fraction slurry of dispersed kaolin is subjected to a partial filtration by passing same in cross flow relation to a microporous membrane through which substantially none of the suspended kaolin particles pass, to raise the solids content of the said slurry to at least 20%.

Abstract: An improvement is disclosed in the method for producing a calcined kaolin clay powder for use in paper manufacture, by the steps of wet beneficiating a kaolin crude, drying the beneficiated crude, milling the dried beneficiated crude to provide a calciner feed, and calcining the feed to destroy the crystallinity thereof and provide an amorphous calcined kaolin powder. According to the improvement, the dried beneficiated crude is milled and classified to provide a calciner feed having substantially no +325 mesh residue, and not greater than 0.0003% by weight +635 mesh residue. This enables lowered abrasion in the calcined powder, and lowered viscocity in the slurried calcined powder product to thereby enable a higher solids slurry.

Abstract: An improved process for producing a aggregated composite 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 mixture of kaolin and one or more additional feed minerals with a previously hydrolyzed organic silicon compound, such as hydrolyzed tetraethoxysilane, and then recovering the aggregated composite pigment.