Abstract: Disclosed is a novel form of particulate precipitated aragonite, and a novel process for producing it.

Abstract: Mesoporous metal carbonate structures are formed by providing a solution containing a non-ionic surfactant and a calcium acetate salt, adding sufficient base to react with the acidic byproducts to be formed by the addition of carbon dioxide, and adding carbon dioxide, thereby forming a mesoporous metal carbonate structure containing the metal from said metal salt.

Abstract: Inexpensive spindle- or rice-like calcium carbonate giving useful properties for brightness, opacity and wire abrasion resistance as a paper filler is provided by taking advantage of the causticization step. When a white liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 10% by weight or less and is slaked with the white liquor at a concentration of 20 to 60% to prepare a milk of lime. When a green liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 0.1 to 10% by weight and is slaked with the green liquor at a concentration of 20 to 60% to prepare a milk of lime. In a second step, causticization reaction takes place at a green liquor loading rate of 0.02 to 0.5 cc (green liquor)/min/g (quick lime) at a reaction temperature of 20 to 105° C. to afford spindle- or rice-like calcium carbonate.

Abstract: Disclosed is a novel form of particulate precipitated aragonite, and a novel process for producing it.

Abstract: A method of making a composite pigment of precipitated calcium carbonate (PCC) and a silicon compound, in which the resulting composite pigment is endowed with an excellent combination of optical and mechanical properties. Among other things, a PCC/silicate composite pigment made according to this invention imparts increased bulk, light scattering power, porosity and printing properties to paper. The composite pigment material made according to this invention also is very competitive from the standpoint of its production cost. The method for making the composite pigment includes the step of introducing a soluble silicate compound into an aqueous medium containing a precipitate of calcium carbonate formed by carbonation of lime milk, and at a time when the calcium carbonate precipitation reaction has progressed to near completion.

Abstract: The invention concerns precipitated calcium carbonate products containing polynuclear regular agglomerates having a number of calcium carbonate particles (aggregates) attached to each other and having a particle size of about 40 to 200 nm. According to the invention, these products are prepared by adjusting the Z potential of the calcium carbonate suspension to −1 . . . −20 mV by adjusting the pH of the suspension to 6.5 . . . 9.5. The pH of the calcium carbonate slurry obtained by causticizing is adjusted to a desired value in a box filter, where after the suspension is stirred by a heavy-duty mixer such that it is subjected to differences of about 50 to 200 m/s in peripheral speed. The products according to the invention have good opacity and are very well suited for coating paper.

Abstract: Ground calcium carbonate compositions having narrow particle size distributions and a method for producing the compositions. The method involves forming a substantially dispersant-free calcium carbonate suspension, wet-grinding the suspension, and aging the suspension. The method does not require the use of classification equipment and the aging process does not require heating.

Abstract: Compositions comprising an aqueous calcium Hydroxide slurry with solids loading of 25-65 wt. %, an acidic polymer or water-soluble salt thereof and a co-additive are prepared. Also claimed are methods for the preparation thereof. The composition has low viscosity and remains flowable after several days.

Abstract: The present invention relates to a stabilized calcium carbonate filler, a process for stabilizing calcium carbonate, the use of the stabilized filler in a paper making system, and an improved paper making process wherein calcium carbonate is used as a filler. Specifically, the invention relates to a process wherein the rate of dissolution of calcium carbonate filler is retarded as compared to the rate found in conventional paper making processes. The rate of dissolution is retarded by addition of carbon dioxide to a slurry containing the calcium carbonate filler.

Abstract: A method for preparing a surface-modified calcium carbonate useful in the synthesis of polyesters such as polyethylene terephthalate, polybutylene terephthalate, etc. to improve the polymer's friction coefficient, which method comprises the step of forming a dispersion comprising calcium carbonate particles and a bi-functional reagent having two functional linking substituents consisting of a first substituent linking to the calcium carbonate particles and a second substituent which can link to the polyester, thereby bonding the calcium carbonate to the polyester through the bifunctional linking reagent; and surface-modified calcium carbonate and polyesters containing same.

Abstract: Calcium carbonate in the form of aragonite crystals suitable for use as a filler for papermaking to give useful properties for bulk, whiteness, opacity, wire abrasion and yield is obtained by taking advantage of the causticization step.

Abstract: The invention is based on the idea of preparing porous calcium carbonate particles via a degradation reaction from a crystalline initial material which contains the initial components for forming calcium carbonate and additionally initial components for forming the reaction products to be removed from the initial material. In the reaction a substantial portion of the calcium carbonate forms a porous frame in the space occupied by the initial material, around the open space left by the matter leaving the initial material. The invention is also based on the use of such porous calcium carbonate particles as a pigment absorbing printing inks or their solvents on the surface of a printing substrate.

Abstract: The invention provides a method of making ≧4 kHz repetition rate argon fluoride excimer laser crystal optics. The method includes providing a magnesium fluoride crystal solid precursor, nonmetallically crushing the magnesium fluoride solid precursor to provide a crushed low metal contaminant magnesium fluoride feedstock, providing a magnesium fluoride crystal growth crucible, loading the crushed magnesium fluoride feedstock into the crystal growth crucible, melting the loaded crushed magnesium fluoride feedstock to provide a precrystalline magnesium fluoride melt, growing an oriented magnesium fluoride crystal from the precrystalline magnesium fluoride melt, cooling the grown magnesium fluoride crystal to provide a magnesium fluoride laser optical crystal and forming the magnesium fluoride laser crystal into an excimer laser crystal optic for transmitting a high repetition rate (≧4 kHz repetition rate) excimer laser output.

Abstract: The present invention includes methods and apparatus useful in the removal of air pollutants. More specifically, this invention relates to methods and apparatus useful in mitigating major air pollutants (SOx and NOx) and trace toxins from coal-fired combustors. Using a method or apparatus of the present invention, a coal-fired combustor may be retrofitted to accommodate combined SOx/NOx removal technology for solid waste reduction and environmentally responsible utilization of dry flue gas (FGD) desulfurization product. The combined SOx/NOx control technology may integrate enhanced removal of SO2 at high to medium temperatures using a desulfurization process of the present invention with selective catalytic reduction technology for NOx. The reactivation of spent sorbent and dry FGD product may result in a more complete utilization of the ash and sorbent in the reduction of SO2 emissions, thereby reducing significantly the amount of sorbent used and the volume of by-product generated.

Abstract: Disclosed is an inorganic dispersant having a high specific surface area and a high surface activity which comprises a calcium phosphate type compound having a specific particle composition, particle shape, particle size and dispersibility, and specific surface area. When used as a suspension polymerization stabilizer, it provides polymer particles having a uniform and sharp particle size distribution, and when the polymer particles are contained in an unsaturated polyester resin composition and a toner composition, the obtained compositions have excellent quality.

Abstract: Ground calcium carbonate compositions having narrow particle size distributions and a method for producing the compositions. The method involves forming a substantially dispersant-free calcium carbonate suspension, wet-grinding the suspension, and aging the suspension. The method does not require the use of classification equipment and the aging process does not require heating.

Abstract: A composition for reducing deposition of a mineral salt from an aqueous supersaturated solution onto a solid surface in contact with the aqueous supersaturated solution which composition comprises a dispersion of either (i) seed crystals of the mineral salt in an aqueous solution of the mineral salt or (ii) seed crystals of a salt isomorphous with the mineral salt in an aqueous solution of the isomorphous salt wherein the dispersed seed crystals are of Mean particle size of less than 2.5 microns.

Abstract: Composite pigments comprising particles of silicate or oxide minerals having deposited thereon a multiplicity of particles of a metal carbonate as a result of in-situ precipitation.

Abstract: Processes for making high quality PCC compositions, and the resulting PCC products thereof. A precipitated calcium carbonate (PCC) composition is prepared by a process comprising the step of wet media mill grinding an aqueous slurry of PCC made by carbonation of lime milk, with the grinding being done at a low solids content in a plurality of separate grinding stages, which can done while essentially free of the presence of organic dispersant. After the multi-stage wet grinding step, the ground PCC slurry is partially dewatered in the presence of an organic dispersant in a solid bowl centrifuge. Then, the partially dewatered PCC slurry is subjected, in the presence of an organic dispersant, to fluid shearing forces created in a rotor/stator type mixer. While these three steps are advantageously used together within a single PCC process flow for optimal effect, the individual steps also can be incorporated singly or in lesser combinations thereof into different PCC manufacturing schemes to beneficial effect.

Abstract: A method of preparing a modified cationic layer compound which includes providing a layer compound of the general formula (I): [EeZzDdVv(OH−)x](An−)a.qH2O  (I) wherein E represents one or more monovalent alkali metal cations, e represents a number of from 0 to about 2, Z represents one or more divalent metal cations, z represents a number of from 0 to about 6, D represents one or more trivalent metal cations, d represents a number of from 0 to about 3, V represents one or more tetravalent metal cations, v represents a number of from 0 to about 1, (An−) represents an acid anion wherein n represents an integer of from 1 to 3, q represents a number of from about 1 to about 10, and wherein x>a and e+2z+3d+4v=x+na; subjecting the layer compound to crystallization to provide a resultant material; and subjecting the resultant material to steam drying at a temperature of from about 200° C. to about 260° C.

Abstract: Bimolecular coated calcium carbonate and a process for controlled surface treatment of calcium carbonate according to which an amount of coating determined from the mean particle diameter (dp) of the calcium carbonate is contacted with the calcium carbonate particles. The way in which the amount of coating agent is determined enables purposeful control of the properties of the coated calcium carbonate particles to adapt them for use as functional filling materials in different technical applications.

Abstract: Precipitated calcium carbonate crystals of selected crystal habit. A pressure carbonation process is used to manufacture precipitated calcium carbonate. A slurry of calcium hydroxide is agitated in a pressurized reactor, and carbon dioxide is provided to a reactor to produce calcium ions and carbonate ions that react under pressure to produce precipitated calcium carbonate at a high reaction rate. Control of process conditions such as pressure, temperature, and hydroxide slurry concentration, enables production of (1) a desired crystal habit (including sclenohedral, rhombohedral, stacked rombohedral, or aragonite calcium carbonate crystal structures), (2) a desired crystal size, or (3) a desired crystal aspect ratio. The precipitated calcium carbonate produced by the process is useful as either a paper filler or as an ingredient in paper coatings, and provides a paper product with improved properties.

Abstract: A process for the preparation of potassium sulfate, sodium bicarbonate and sodium carbonate. The process involves the treatment of potash brines by the reaction of sodium chloride and potassium chloride with calcium sulfate and sodium sulfate. Syngenite precipitate (CaSO4.K2SO4&khgr;H2O) is produced and a first filtrate containing sodium chloride and potassium chloride. The syngenite precipitate is reacted with ammonium bicarbonate at between 70° C. and 100° C., with the result being calcium carbonate precipitate and a second filtrate containing ammonium sulfate and potassium sulfate. The second filtrate is cooled to a temperature of between 20° C. and 50° C. and treated with potassium chloride. A potassium sulfate precipitate results. The sodium bicarbonate is precipitated from the first filtrate by the addition of ammonium bicarbonate to the first precipitate. The sodium bicarbonate may be calcined to form sodium carbonate.

Abstract: A process is provided for producing potassium sulfate by reacting ammonium sulfate and potassium chloride at a temperature of about 30 to 40° C. to produce a slurry containing K2SO4·NH4·2SO4 double salt, and reacting this double salt with an aqueous solution containing potassium chloride at a temperature of about 30° C. to produce a slurry containing potassium sulfate. The slurry containing potassium sulfate is subjected to a solids/liquid separation step to obtain potassium sulfate crystals having a size in the range of about 20 mesh to about 150 mesh.

Abstract: Novel precipitated calcium carbonate particles of varying size and shape, are prepared by adding gaseous carbon dioxide to an aqueous slurry containing basic calcium carbonate under a selectively controlled reaction environment. In its preferred embodiment precipitated calcium carbonate particles having a prismatic shape and an average equivalent spheroidal diameter of between about 1.5 and about 6.5 microns; large irregularly shaped particles having an average equivalent spherical diameter of between about 15 and about 25 microns; and multi-faceted spheroidal particles having an average equivalent spherical diameter of between 5 and about 15 microns, are provided. The reaction environment includes temperatures of between 0° C. and 60° C. and a surface active polyphosphate additive present in amounts of from about 0.1 and about 1.0 percent by weight.

Abstract: Novel, fine particulate synthetic chalcoalumite, process for preparation thereof, and a heat insulating agent and agricultural film containing said fine, particulate synthetic chalcoalumite. The above objects are met by synthetic chalcoalumite represented by formula (1) below: (M12+)a−x(M22+)Al3+4(OH)b(An−)c. mH2O  (1)  (in which M12+ stands for Zn2+ or Cu2+,  M22+ is at least one divalent metal ion selected from Ni2+, Co2+, Cu2+, Zn2+ and Mg2+,  a is 0.3<a<2.0 (with the proviso that M1 and M2 are not the same),  x is 0 ≦x<1.0, and x<a  b is 10<b<14,  An− is at least one selected from SO42−, HPO42−, CO32−, SO32−, HPO32−, NO3−, H2PO4−, Cl−, OH− and silicate ion,  c is 0.4<c<2.

Abstract: A process for stabilizing a halogen-containing plastic against thermal or photochemical degradation by adding to the plastic an additive consisting essentially of cationic layer compounds corresponding to general formula (I): [M(II)xAl(OH)y](An−)z.mH2O  (I) where M(II) represents at least one divalent metal ion and An− represents an acid anion having the charge n−(n=1, 2 or 3) and 1<x<5, y>z, (y+nz)=2x+3 and 0<m<10, and wherein the cationic layer compounds have been prepared by adding alkali metal hydroxide to a water-containing mixture of at least one source of divalent metal ions M(II), one source of the anion An− and crystalline aluminum hydroxide in a quantity of 1 to 20 mole-%, based on aluminum hydroxide, heating the mixture for 10 to 240 minutes at a temperature of 100° C. to 240° C., and drying the mixture to form a powder without previous separation of the solid from the aqueous phase.

Abstract: A process for the production of precipitated calcium carbonate. A slurry of calcium hydroxide is agitated in a pressurized reactor, and carbon dioxide is provided under pressure to the reactor to produce precipitated calcium carbonate at a high reaction rate. Carbon dioxide is utilized at a high efficiency. Solubilized calcium ions and carbonate ions react to produce a calcium carbonate precipitate. Control of process conditions such as temperature, slurry concentration, and pressure, enables production of a desired crystal habit (including sclenohedral, rhombohedral, stacked rombohedral, or aragonite crystal structures), crystal size, or crystal aspect ratio. The precipitated calcium carbonate produced by the process under pressure is useful as either a paper filler or as an ingredient in paper coatings, and provides a paper product with improved preselected properties, which properties include opacity, density, and/or brightness.

Abstract: Enhanced macromixing, mesomixing, and micromixing of multiple discrete reactant streams, particularly for precipitation reactions of low density pumpable fluids, are obtained by controlled continuous high pressure multiple reactant streams flowing into a chemical mixer/reactor. Individual reactant streams are pressurized to about 8,000 to 50,000 psi and achieve velocities up to about 250 meters/second in the final stage of the chemical mixer/reactor. Reactant flows are controlled by a combination of a fixed restriction and a variable driving pump.

Abstract: In this process for working up RESH or shredder light fractions, the RESH or shredder light fractions are charged into a fluidized bed gasifier. Hot wind or combustion offgases having a temperature above 450° C. are blown into the fluidized bed through nozzles while forming a counterflow grinding space. CaCO3 is introduced into the fluidized bed and calcined in the grinding space to effect disintegration.

Abstract: Method of recovering calcium carbonate from waste material or contained natural calcic material. Calcium is recovered by prepariag an aqueous suspension the material containing calcium to be recovered and by lowering the pH of the suspension to pH<6, preferably pH<4, for providing a spension including an acidic liquid phase containing the calcium compounds in soluble form. Thereafter the pH of the liquid is raised to pH>6, preferably pH>7, by mixing a base therein, for precipitating the main portion of aluminium therein. Thereafter the neutral or basic liquid phase is carbonized by introducing Na2CO3 or NaHCO3 therein, for precipitation of the calcium compounds as CaCO3.

Abstract: Inexpensive spindle- or needle-like calcium carbonate giving useful properties for bulk, brightness, opacity, wire abrasion resistance and yield as a paper filler is provided by taking advantage of the causticization step. In a first step, a quick lime having a calcium carbonate content of 10% by weight or less is slaked with a liquor having a pH of 5.5 to 13.5 at a concentration of 20 to 60% to prepare a milk of lime. In a second step, causticization reaction takes place at a green liquor loading rate of 0.02 to 0.5 cc (green liquor)/min/g (quick lime) at a reaction temperature of 20 to 105° C. to afford spindle- or needle-like calcium carbonate.

Abstract: A method is provided for removing sulfur dioxide and carbon dioxide out of gases from, for example, the combustion of sulfur containing fossil fuels. The sulfur dioxide and carbon dioxide contaminated gas is first contacted with an aqueous solution containing dimethyl sulfoxide and alkaline earth metal ions, wherein the aqueous solution is at an acidic pH, for example, at a pH of from about 2 to about less than 7, so that the sulfur dioxide in the gas is dissolved in the aqueous solution and, subsequently, reacts with the alkaline earth metal ions to form alkaline earth metal sulfates and alkaline earth metal sulfites. The gas is then contacted with an aqueous solution containing dimethyl sulfoxide and alkaline earth metal ions, wherein this aqueous solution is at a pH that is greater than 7 so that the carbon dioxide in the gas is dissolved in the aqueous solution and, subsequently, reacts with the alkaline earth metal ions to form alkaline earth metal carbonates.

Abstract: Processes for use of a controlled continuous high pressure multiple reactant streams flowing into a chemical mixer/reactor. Individual reactant streams are pressurized to about 8,000 to 50,000 psi and achieve velocities up to about 250 meters/second in the final stage of the chemical mixer/reactor.

Abstract: A method of significantly improving the brightness and shade properties of a high quality PCC product. The method includes providing a calcium containing feed source that contains discoloring impurities. The calcium containing feed source is formed into an aqueous slurry of calcium carbonate. Thereafter, the slurry is fine screened through a 325 mesh screen in order to yield a slurry of filler grade calcium carbonate. The filler grade calcium carbonate slurry is wet milled in order to liberate the discoloring impurities and reduce the median particle size of the calcium carbonate to less than 2 microns. The discoloring impurities are then magnetically separated from the milled calcium carbonate slurry by subjecting the slurry to a high intensity magnetic filed. After the magnetic separation step, the purified slurry may be de-watered to yield a dry powder; or alternatively, the slurry may be retained in aqueous form.

Abstract: A method for forming a silica coating on at least a portion of the surface of alkaline earth metal carbonate particulates in aqueous suspension and the silica-coated alkaline earth metal carbonate so produced are claimed. The claimed method consists of allowing soluble silicate ions in the aqueous phase to slowly react with the alkaline earth metal carbonate surface to form silica micro-particulates on the surface. This silica coating confers upon the composition unique properties among which are pronounced thixotropic behavior when incorporated into an aqueous suspension and increased oil absorption when dry. The pigment produced by this method is especially suited for use as a filler in paper.

Abstract: A method for the manufacture of precipitated calcium carbonate from impure calcium oxide of improved color is disclosed. The method comprises admixing impure calcium oxide with an aqueous solution consisting essentially of a salt of at least one compound selected from the group consisting of organic amines of the formula RNH.sub.2 and alkanolamines of the formula NH.sub.2 (R.sup.1 OH), where R and R.sup.1 are alkyl groups of 1-4 carbon atoms, and hydrochloric or nitric acid. The solution obtained is treated with a reducing agent e.g. sodium hydrosulphite, separated from insoluble matter and then treated with carbon dioxide or the carbonate of the amine or alkanolamine at a temperature of at least 50.degree. C. Preferably, the amine of the salt and of the carbonate are the same, and the salt is used in at least the stoichiometric amount to dissolve the lime.

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: A method for producing precipitated calcium carbonate by reacting an aqueous solution of calcium nitrate [Ca(NO.sub.3).sub.2 ] with an aqueous solution of ammonium carbonate [(NH.sub.4).sub.2 CO.sub.3 ] and allowing calcium carbonate to precipitate from the resultant mixture containing nitrate [NH.sub.4 NO.sub.3 ] in the mother liquor, the process being characterized in that: (i) the calcium nitrate [Ca(NO.sub.3).sub.2)] solution utilized in the processes is prepared by slaking lime [CaO] in water in the presence of ammonium nitrate [NH.sub.4 NO.sub.3 ] to form calcium nitrate [Ca(NO.sub.3).sub.2 ] and ammonium hydroxide [NH.sub.4 OH] in solution, filtering the solution to render it solids free, and heating the filtrate to dissociate the ammonium hydroxide [NH.sub.4 OH] and to drive ammonia gas [NH.sub.3 ] from the solution; (ii) the ammonium carbonate (NH.sub.4).sub.2 CO.sub.3 solution utilized is prepared by absorbing ammonia gas [NH.sub.3 ] and carbon dioxide gas [CO.sub.

Abstract: This invention involves new compositions and methods of use and delivery of amorphous calcium compounds such as: amorphous calcium phosphate (ACP), amorphous calcium phosphate fluoride (ACPF), amorphous calcium carbonate phosphate (ACCP), amorphous calcium carbonate phosphate fluoride (ACCPF), and amorphous calcium fluoride (ACF) for use in remineralizing and fluoridating teeth. These amorphous compounds or solutions which form the amorphous compounds or calcium phosphate jelly which forms the amorphous compounds, when applied either onto or into dental tissue to prevent and/or repair dental weaknesses such as dental caries, exposed roots and dentin sensitivity. The compounds have the highest solubilities, fastest formation rates and fastest conversion rates (to apatite) among all the calcium phosphates under physiological conditions. Moreover, in the presence to fluoride the amorphous compound convert rapidly to fluoride containing apatite.

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: Hydromagnesite-magnesium hydroxide compositions are prepared which, when used as fillers in smoking article wrappers, significantly reduce the amount of sidestream smoke produced by the burning smoking article while providing the smoking article with good subjective characteristics.

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: A synthetic chalcoalumite compound represented by the formula (1)(Zn.sub.a-x.sup.2+ M.sub.x.sup.2+)Al.sub.4.sup.3+ (OH).sub.b (A.sup.n-).sub.c.mH.sub.2 O (1)whereinM.sup.2+ represents at least one of Cu, Ni, Co and Mg;a represents 0.3<a<2.0;x represents 0.ltoreq.x<1.0;b represents 10<b<14;A.sup.n- represents one or two selected from SO.sub.4.sup.2-, HPO.sub.4.sup.2-, CO.sub.3.sup.2-, CrO.sub.4.sup.2-, SiO.sub.3.sup.2-, NO.sub.3.sup.2-, OH.sup.- and Cl.sup.- ;c represents 0.4<c<2.0 andm represents a number of 1 to 4,and a process for the production thereof.

Abstract: Methods are disclosed in which first and second reactant salts and, optionally, a complexing agent are added to a non-aqueous reaction solvent to form a reaction system. The reactant salts, which are substantially soluble and reactive with each other in water to form a first crystallite of calcium carbonate, are present in the reaction solvent in relative amounts that are sufficient to form a desired amount of the calcium carbonate in the reaction system. The complexing agent, if present, is a crown ether or other cyclic or acyclic polydentate chelating agent that, in the reaction solvent, forms chelation complexes with at least one of the reactant salts. Reaction of the first and second reactant salts in the reaction solvent forms a second crystallite precipitate comprising crystals of calcium carbonate having a different habit or morphology from calcium carbonate crystals in the first crystallite that would otherwise be formable in water by reaction of similar amounts of the first and second reactant salts.

Abstract: A novel CaCO.sub.3 sorbent with its physical properties tailored for high SO.sub.2 removal is produced in accordance with the present invention. The surface area, porosity and the distribution of pore sizes of the sorbent have been designed and controlled to give rise to the optimum internal structure necessary for high SO.sub.2 removal. The CaCO.sub.3 sorbent possesses 60 m.sup.2 /g surface area and 0.18 cc/g pore volume and exhibits extraordinary reactivity towards SO.sub.2 (70% utilization in 530 milliseconds at 1080.degree. C. and 3900 ppm SO.sub.2 concentration) when compared with other carbonate and hydrate sorbents in our laboratory reactor system. The sorbent may be produced by precipitation in a slurry bubble column reactor system and preferably contains about 2% by weight of a surfactant which is added during its preparation and improves the properties of CaCO.sub.3 in the course of precipitation. The high utilization of this tailored CaCO.sub.

Abstract: A process for the precipitation of discrete prismatic calcium carbonate particles by carbonation of aqueous calcium hydroxide containing a saccharide or polysaccharide or a saccaride or polysaccharide and a metal ion at temperatures of from about 8.degree. C. to about 64.degree. C. is disclosed. The resulting product has specific surface areas between about 10 m.sup.2 /g and about 120 m.sup.2 /g and is useful in paints, plastics, paper coating, paper filling, and pharmaceutical applications.

Abstract: A method and plant for heat treatment of lime sludge (CaCO.sub.3) formed by the causticizing process during the manufacture of paper pulp. The lime sludge is dried and pulverized in a first process stage and preheated in a second process stage by means of hot exhaust gas coming from a kiln. In order to ensure that the temperature in the second process stage does not exceed a predetermined temperature lying within the range from 400.degree.-600.degree. C., the relationship between the amount of energy available in the exhaust gas for preheating in the second process stage and the amount of accumulated energy in the material which is to be preheated is regulated.

Abstract: A method for lowering the iron content of calcium carbonate is disclosed. The method involves addition of an iron chelating agent to an aqueous calcium carbonate slurry, reducing the pH of the aqueous calcium carbonate by employing carbon dioxide containing gas, while maintaining the aqueous calcium carbonate slurry at an elevated temperature. The slurry is stirred, filtered, washed and dried. The calcium carbonate product resulting from the process of the present invention has a reduced iron content.Calcium carbonate produced according to the method of this invention is particularly suitable for use as food or pharmaceutical additives and may also be useful as a filler in papermaking processes or as additives in plastic products.

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.