Abstract: A method of producing a dispersed aqueous suspension of an inorganic particulate material which includes the steps of (a) preparing an aqueous suspension of calcium carbonate particles having a particle size distribution such that at least 35% by weight have an esd less than 24 .mu.m, the solids concentration of the suspension being no more than 40% by dry weight; (b) concentrating the suspension by dewatering to increase the solids content to at least 60% by dry weight; and (c) adding a dispersing agent to the concentrated suspension to disperse the calcium carbonate particles and characterized in that the suspension produced by step (c) is pumpable and flowable, the dispersing agent comprising a water soluble copolymer of acrylic acid and maleic acid or a salt thereof having a molar ratio of acrylic acid units to maleic acid units of from 0.5:1 to 10:1 and a mass average molecular mass of from 1,000 to 100,000.

Abstract: A ceiling board coating composition includes water, a binder and a filler, said filler having large particles with an average particle size of a minimum of about 50 microns, medium particles with an average particle size in the range of from about 1.2 to about 30 microns, and small particles which have an average particle size in the range of from about 0.1 to about 1.0 microns.

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 acidic paper, and a process for producing this acid-resistant calcium carbonate is provided. This acid-resistant calcium carbonate composition comprises calcium carbonate and at least about 0.1% to about 25% based on the dry weight of the calcium carbonate, of sodium silicate, together with at least 0.1% to about 25 percent, based on the dry weight of the calcium carbonate, of a weak acid, such as phosphoric acid, formic acid, fluoroboric acid, polyacrylic acid, or alum, or a mixture of weak acids, such as phosphoric acid and polyacrylic acid.

Abstract: An adhesive-free, dry, free-flowing powder composition suitable for use in surface defect detection, where the powder composition comprises a physical mixture of particles of a colorant and particles of an extender, which mixture includes particles of colorant and particles of extender each having a particle size of less than 100 .mu.m. The powder compositions of the invention provide a simple, effective guide coat which readily highlights surface imperfections, such as scratches, orange peel effect and dry over-spray without the need for solvents. Also, there are disclosed methods of using such a powder composition to detect surface imperfections, an apparatus for applying same, a device for refilling such applying apparatus, and coated surfaces formed thereby.

Abstract: A multi-component pigment slurry which comprises at least 50% solids. The slurry is formulated to be admixed into paint and coating compositions to promote TiO.sub.2 extension. The slurry includes a structured pigment, a coarse particle size pigment, and a fine particle size pigment. The structured pigment comprises about 20% to about 55% of the slurry by dry weight and has a median particle size diameter of about 0.7.mu. to about 6.0.mu.. The coarse particle size pigment preferably comprises about 20% to about 60% by weight of the slurry and has a median particle size diameter of about 3.0.mu. to about 10.0.mu.. The fine particle size pigment preferably comprises up to about 50% by dry weight of the slurry and has a median particle size diameter of about 0.2.mu. to about 1.0.mu..

Abstract: The present invention relates to a calcium carbonate composition having both calcite and aragonite crystalline morphology. More particularly, the present invention relates to an acicular calcite and an acicular aragonite product and a method for the production of the same and the use of such as fillers, additives and modifiers of consumer and commercial products such as toothpaste, paper, plastics and sealants. The acicular calcite/aragonite composition of the present invention provides a balance of properties such as sheet bulk, strength, stiffness, and sizing, when employed as a filler for paper. As a coating pigment, the acicular calcite/aragonite product of the present invention provides gloss characteristics suitable for dull and matte grades of low gloss coated paper. Upon further processing such as milling, grinding, or other means of comminution, the resulting product provides gloss characteristics suitable for high gloss coated paper.

Abstract: Disclosed is a system of natural colours consisting of thousands of coloured powders of mineral origin and of materials in or on which pigments have been applied and, afterwards, submitted to at least one thermal treatment and/or irradiation. These natural colours cover the totality of the visible spectrum and offer a great variety of tones, tints and reflections from white to black, including all the rainbow colours. The powders of this system are obtained by mechanical, chemical, thermal and/or physical processes and are used alone or in combination. They are particularly useful to colour materials and, more especially those used in the construction and architectural fields.

Abstract: A slurry containing water, carbonate-containing pigment, and dispersant consisting of 25-70 % by weight of agglomerated carbonate-containing pigment, 0.1-1.0% by weight of a dispersant, the balance being water up to 100%, can be used advantageously in papermaking as well as in the paint and lacquer industry. In a novel process for agglomerating ultra-fine particles in slurries the slurry is subjected to heat treatment until the agglomeration is complete.

Abstract: A process for preparing a coated printing paper by applying a coating solution containing a pigment and an adhesive to a base paper, which comprises coating the base paper with the coating solution containing 30 to 90% by weight, based on 100% by weight of pigment components, of rice grain- or spindle-shaped precipitated calcium carbonate as a pigment component, the precipitated calcium carbonate being produced by slaking calcium oxide with a white liquor, followed by causticization with a green liquor, at a causticizing step during pulp production by the sulfate process or the soda process; whereby the coated printing paper free from uneven gloss, mottling, and trapping unevenness, and excellent in ink drying properties and operability with a blade coater is provided.

Abstract: A filler of inorganic particles, cellulose reactive size and cationic dispersing agent is provided, the use of which results in the capability to obtain the desired sizing level practically unaffected by the level of filler addition.

Abstract: Disclosed is a system of natural colors consisting of thousands of colored powders of mineral origin and of materials in or on which pigments have been applied and, afterwards, submitted to at least one thermal treatment and/or irradiation. These natural colors cover the totality of the visible spectrum and offer a great variety of tones, tints and reflections from white to black, including all the rainbow colors. The powders of this system are obtained by mechanical, chemical, thermal and/or physical processes and are used alone or in combination. They are particularly useful to color materials and, more especially those used in the construction and architectural fields.

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: Disclosed is a system of natural colors consisting of thousands of colored powders of mineral origin and of materials in or on which pigments have been applied and, afterwards, submitted to at least one thermal treatment and/or irradiation. These natural colors cover the totality of the visible spectrum and offer a great variety of tones, tints and reflections from white to black, including all the rainbow colors. The powders of this system are obtained by a combination of two mechanical, chemical, thermal and/or physical processes and are used alone or in combination. They are particularly useful to color materials and, more especially those used in the construction and architectural fields.

Abstract: An inorganic particulate material suitable for use as a pigment material in a paper coating composition has a particle size distribution which when represented as a graph of percentage of weight of particles having an equivalent spherical diameter (esd) of given size versus particle esd expressed in microns and plotted on a logarithmic base 10 scale has the following features: (a) a first peak at the coarse particle size and a second peak at a finer particle size and a dip or trough between the first and second peaks; (b) the mean particle size x.sub.1 of the particles making up the first peak being 2 to 4 microns; (c) the relationship between the first and second peaks being such that the value of the mean particle size x.sub.2 of the particles making up the second peak is separated in the particle size distribution graph from the value of x.sub.1 by at least 0.5; and (d) the minimum of the dip or trough is at a given particle esd dimension of between 0.5 and 5 microns.

Abstract: Proposed is a method for the preparation of an aqueous slurry of calcium carbonate particles suitable as a base pigment in the preparation of a paper coating composition having excellent water retentivity and high solid concentration with good flowability, which contains precipitated and ground calcium carbonate particles in combination in a specified weight proportion and characterized by several parameters. The aqueous slurry is prepared in a process comprising the steps of: (a) subjecting an aqueous slurry or wet cake containing a specified amount of specific precipitated calcium carbonate particles to a primary dispersing treatment using a mixer to a specified extent; (b) admixing the aqueous slurry with a specified amount of specific ground calcium carbonate particles; (c) subjecting the aqueous slurry to a secondary dispersing treatment using a mixer to a specified extent; and (d) subjecting the aqueous slurry to a tertiary dispersing treatment using a sand grinder to a specified extent.

Abstract: A coating color comprising 28-51% by weight of water, 43-64% by weight of carbonate-containing pigment with a specific particle distribution and a particle diameter of 0.18-0.28 .mu.m and a specific surface area of 19-26 M.sup.2 /g and 6-8% by weight of conventional binding agents and additives may be employed with advantage for coated papers. The coating color is produced by wet milling of the carbonate-containing pigment without the addition of dispersing or wetting agents at a solids concentration of 30-20% by weight in an agitating ball mill, subsequent concentration, re-dispersal and the addition of binding agents, water and additives.

Abstract: The present invention relates to a process for preparing a pigment composition whereby a mixture of an organic pigment and an inorganic filler is subjected to an air jet milling step. The inventive process is an environmentally friendly process which yields pigments having outstanding dispersibility and wetting characteristics when incorporated in plastics, aqueous or solvent based coatings and inks.

Abstract: There is disclosed a method for the preparation of a precipitated calcium carbonate (PCC) for use as a pigment in paper coating compositions, the method comprising the steps of (a) carbonating an aqueous lime-containing medium to produce an aqueous suspension of a PCC predominantly in a selected crystal form, (b) at least partially dewatering the PCC-containing suspension; and (c) subjecting the PCC-containing suspension to comminution by high shear attrition grinding with an attrition grinding medium. Steps (b) and (c) may be applied in either order, ie. (b) followed by (c) or alternatively (c) followed by (b). The dewatering step (b) is preferably carried out using a pressure filter device operating at a pressure of at least 5 MPa, preferably at least 10 MPa. A pH reduction step may be applied after steps (b) and (c). Also disclosed are pigments produced by the method and pigment and paper coating compositions including such pigments.

Abstract: Finishing agents comprise the combination of an alkoxysilane surface active agent, a silanol condensing catalyst, and a nonaqueous liquid or solid medium, or the combination of an alkoxysilane surface active agent, an acid catalyst and a liquid or solid medium. In the latter embodiment, it is preferred that at least one of the alkoxysilane surface active agent and the acid catalyst be microencapsuled. The finishing agent permits formation of chemically adsorbed protecting films. Such protecting films are used for substrates of such equipments as electronics products, electric domestic products, automobiles, industrial equipment, mirrors, lenses for glasses and the like. The protecting films have a durability and heat, weather and abrasion resistance, and also water and oil repellent properties.

Abstract: A method of recycling mineral pigments contained in the waste produced from the deinking of wastepaper. The deink residue is heated in an oxygen-containing atmosphere to a temperature sufficient to completely oxidize all the organic hydrocarbons present. Heat, water, and carbon dioxide also are generated and may be captured and reused in the process. Combustion causes a chemical reaction to occur, so that the original pigments contained in the deink residue are converted to new, stable mineral forms. The ash from the combustion is primarily a mixture of gehlenite (Ca.sub.2 Al.sub.2,SiO.sub.7), anorthite (CaAl.sub.2 Si.sub.2 O.sub.8) and perovskite (CaTiO.sub.3). The ash containing the mixed mineral phases is added to a reactor in which carbon dioxide gas is bubbled through an aqueous slurry of calcium hydroxide so that precipitated calcium carbonate (PCC) is produced.

Abstract: A process for improving the rheological properties of an aqueous suspension of a particulate inorganic material which comprises the steps of: (a) forming an aqueous suspension of the particulate inorganic material and an effective amount of an anionic polyelectrolyte dispersing agent; (b) diluting the suspension formed in step (a) with water while maintaining the particulate in the dispersed state of step (a) to give a solids concentration of not less than 20% by weight of the particulate inorganic material; and (c) reconcentrating the diluted suspension formed in step (b) to give a solids concentration of at least 50% by weight of the particulate inorganic material.

Abstract: The disclosure describes a method of incinerating combustible wastes comprising the step of incinerating said combustible wastes in the presence of a calcium compound and particles selected from the group consisting of iron oxide particles, ferric oxide hydroxide particles and mixed particles thereof.

Abstract: The present invention relates to a novel composite product which is composed of a fibrocrystalline heterogeneous structure consisting of:on the one hand a plurality of fibers of expanded specific surface area and of hydrophilic character, having a substantial quantity of microfibrils on their surface, andon the other hand crystals of precipitated calcium carbonate (PCC), organized essentially in clusters of granules, the majority of which trap the microfibrils and are joined directly thereto by mechanical bonding.

Abstract: A method of coating paper with a paper coating composition having a solids concentration of at least 45% by weight, consisting essentially of an aqueous cationic dispersion of a particulate calcium carbonate pigment and a nonionic or cationic adhesive, wherein the pigment has a particle size distribution such that no more than 1% by weight of the particles have an equivalent spherical diameter larger than 10 microns, at least 65% by weight of the particles have an equivalent spherical diameter smaller than 2 microns and not more than 10% by weight of the particles have an equivalent spherical diameter smaller than 0.25 micron, and wherein said pigment is dispersed with a combination of a cationic polyelectrolyte and an anionic polyelectrolyte, with the amount of cationic polyelectrolyte being in the range of about 0.01% to about 1.5% by weight, based on the weight of the dry pigment, and with the amount of anionic polyelectrolyte being in the range of about 0.01% to about 0.5% by weight.

Abstract: A process is disclosed for making a resin additive for a liquid paint. The process comprises of the steps selecting a thermosettable organic resin, curing the resin to form a cured thermoset resin, and particulizing the cured resin to a size no greater than about 20 .mu.m. The present invention is particularly useful in making environmentally friendly paint formulations.

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 process is provided for the selective aggregation of the fine and ultrafine particles present in an anionically or cationically dispersed mineral pigment slurry, such that an aggregated structure is formed which contains within it a labyrinth of internal voids or pores, which collectively function as light scattering centers. The aggregates are formed from an assemblage of fine mineral particles, interconnected or bonded together with small quantities of a cationic or anionic polymer or agent of low molecular weight. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and colloidal particles. The net charge present on the aggregated particles is lower than that of the feed material. These mineral aggregates are then of a suitable size and surface charge to be retained well in a fiber web by a combination of filtration retention and adsorption retention, and provide added bulk and opacity to the finished sheet of paper.

Abstract: A method for producing bulking and opacifying kaolin fillers for filling cellulosic products is disclosed. An aqueous slurry of anionically dispersed kaolin particles is formed at 1 to 30% solids. A low-molecular-weight cationic aggregating agent is then added to the dispersed slurry to selectively aggregate fine and ultra-fine particles. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and ultra-fine or colloidal particles. The net charge present on the aggregated particles is lower than that of the feed material. The aggregated structure contains within it a labyrinth of internal voids or pores. These mineral aggregates are then of a suitable size and surface charge to be retained well in a fiber web, and provide added bulk and opacity to the cellulosic products.

Abstract: A method for producing structured calcium carbonate pigments for coating paper is disclosed. An aqueous slurry of anionically dispersed calcium carbonate particles is formed at 1 to 30 percent solids. A low-molecular-weight cationically charged aggregating agent is then added to the slurry to selectively aggregate fine and ultra-fine particles. The resultant aggregates are of larger mean particle size than the mixture of particles in the original slurry and contain little or no fine and colloidal particles. The net charge present on the aggregated particles is lower than that of the original mineral particles. The low solids suspension of the aggregated mineral particles is then dewatered, or increased in solids to form a slurry with a solids content greater than 60 percent by weight.

Abstract: The disclosure describes pigment compositions containing an organic pigment and a transparent filler having a mean particle size less than 10 .mu.m and a narrow particle size distribution; as well as methods of preparing the pigment compositions. The pigment compositions are useful for pigmenting high-molecular-weight organic materials; especially coating compositions, curable ink systems, plastics, as well as for use in laser marking applications.

Abstract: The present invention provides a filler for wood products, especially those intended for indoor use, This filler can include a putty including a mixture of calcium sulphate and calcium oxide (or a compound forming calcium oxide when heated); at least one mineral pigment; and an agent for retarding the setting of the putty. The invention also contemplates a method for filling wood products. In accordance with this method, one fills an orifice within the wood product with a filler which includes a putty including a mixture of calcium sulphate and calcium oxide (or a compound forming calcium oxide when heated); and at least one mineral pigment. The filler is then smoothed and a surface of the filled wood product is finished.

Abstract: A method is disclosed for producing bulking and opacifying pigments for filling paper by the selective aggregation of fine particles in an anionically or cationically dispersed slurry, such that an aggregated structure is formed which contains within it a labyrinth of internal voids or pores. The aqueous slurry is formed at one to thirty percent solids. A low molecular weight agent of opposite ionic charge is then added to the slurry to selectively aggregate the fine particles present. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and colloidal particles. The net charge present on the aggregated particles is lower than that of the feed 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: Carbonate containing mineral fillers, and more particularly natural and/or precipitated calcium carbonates, characterized by the following grain size distribution:______________________________________ <61 .mu.m: 100% <56 .mu.m: 95-100% <40 .mu.m: 90-100% <20 .mu.m: 48-95% <10 .mu.m: 15-52% <5 .mu.m: 9-28% <1 .mu.m: 0-10% d.sub.50 : 9.6-20.5 .mu.m ______________________________________may with advantage be employed as mineral fillers, preferably as matting agents and in a more especially preferred fashion for aqueous paint systems.

Abstract: A CaCO.sub.3 -talc coating pigment slurry consists of the following four co-ground components:a. 24 to 64% by weight CaCo.sub.3,b. 5 to 48% by weight talc,c. 20 to 40% by weight H.sub.2 O, andd. an adjuvant combination consisting of0.05 to 1.4% by weight of at least one commercially available grinding acid and0.05 to 1.2% by weight of at least one commercially available dispersing agent,wherein the mixed pigments have an average statistical particle diameter of 0.4 .mu.m to 1.5 .mu.m. That coating pigment slurry can be used to special advantage to prepare a composition for coating papers for gravure printing.

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 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 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 opacifying kaolin clay pigment with improved rheological properties and good opacifying characteristics is manufactured by a process which comprises reacting a mixture of water, kaolin clay and calcium carbonate with a hydroxide component at a temperature of at least 60.degree. C.

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: Disclosed is a process for coloring high-molecular-weight coatings and ink systems which comprises uniformly dispersing an effective pigmenting amount of a stir-in pigment in the coating or ink system; wherein the stir-in pigment is an organic pigment crude consisting essentially of non-platelet-shaped particles having an average particle size of from 0.5 to 25 .mu.m and/or a pigment composition consisting essentially of an organic pigment having an average particle size of from 0.01 to 25 .mu.m and inorganic filler pigment.

Abstract: Pigments for use in paper are comprised of structured aggregate clays which are reaction products of kaolin clays and colloidal silicas. Silica modified clays of low treatment level can under certain high-shear mixing conditions be attritioned back to their starting clay particle size consequently yielding silica coated clay particles that provide unique properties. Also provided are structured aggregate clay products produced by the reaction of kaolin clay, colloidal silicas and spacer particles such as titanium dioxide, which products have improved porosity and light scattering characteristics. Also provided are clay slurry products which comprise mixtures of the reaction product of kaolin clay and colloidal silica, and optionally titanium dioxide, blended with other clay products.

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 papermaking process with improved sizing efficiency and reduced size reversion is characterized by the use of a calcium carbonate pigment which is surface treated with an anionic starch-soap complex. The starch-soap complex is precipitated onto the pigment surfaces to provide bonding sites for sizing agents which impart water repellency to the paper. The sizing agents become bound to the starch component of the starch-soap complex to yield more reacted size in paper webs formed from the furnish than would be present without the use of the treated pigment. The use of the surface treated pigment also allows the papermaker to increase the filler content of the paper without sacrificing dry strength properties.

Abstract: There is disclosed a paper coating pigment comprising:(a) from 10% to 100% by weight of a first paper coating pigment having a particle size distribution such that at least 75% by weight of the particles have an equivalent spherical diameter smaller than 2 .mu.m and at least 60% by weight have an equivalent spherical diameter smaller than 1 .mu.m, the average particle aspect ratio of the size fraction having an equivalent spherical diameter predominantly smaller than 1 .mu.m being 25 or greater; and(b) up to 90% by weight of a second paper coating pigment.

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.

Abstract: A functionally modified pigment particle is prepared by mixing a flocculated pigment of kaolin clay or calcium carbonate with a modifier having charge sites opposite in sign to the charge sites of the flocculated pigment. Preferably, the flocculated pigment is an aqueous suspension of filter cake particles. The suspension is non-dispersed, or partially dispersed by neutralization with a strong base such as sodium carbonate. The suspension has a pH in the range of 6-9. Preferred modifiers are a water insoluble or dispersible latex binder, a water or alkali soluble organic or inorganic polymeric binder, a non-film forming organic particle such as plastic pigment, an optical brightener, a fluorocarbon, or combination thereof. When mixed with the filter cake, the modifiers become electrostatically bound to the pigment particles.

Abstract: A novel alkaline earth metal carbonate product for use as a raw material in the glass manufacturing process is disclosed. The alkaline earth metal carbonate becomes a part of the liquid phase in the glass furnace more readily and at a lower temperature; it decomposes to release carbon dioxide gas more rapidly so that all of the gas can escape from the molten glass more easily. Using these alkaline earth metal carbonate compositions, the production capacity of a glass furnace is increased.

Abstract: A simple process for preparing acicular calcium sulphate dihydrate is provided in which a slurry of calcium carbonate containing 100 to 800 grams per liter calcium carbonate is mixed with a solution of sulphuric acid containing 80 to 500 grams per liter sulphuric acid in proportions which produce a calcium sulphate slurry having a pH from 0.5 to 1.5. The process can be used to neutralise by-product sulphuric acid from the preparation of titanium dioxide with crushed limestone. Preferably the calcium sulphate slurry is stirred after formation to reduce the level of unreacted carbonate. The calcium sulphate produced has an aspect ratio of at least 4:1 and has excellent properties for use in paper. The process enables the production of acicular calcium sulphate without employing special crystallisation procedures.

Abstract: A method for preparing granulated alkaline earth metal carbonate, especially barium carbonate and strontium carbonate, by adding a binding agent and optionally water, and granulating the carbonate material by the action of mechanical forces or by accretional granulation in, for example, a flash reactor, with simultaneous drying, and thereafter optionally subjecting the granules to a high-temperature treatment, in which method the material to be granulated and the granulated material do not come in contact with inorganic refractory material either during the granulation or during any subsequent high-temperature treatment.