Abstract: Disclosed are a method and a system for recycling carbon dioxide. The method includes chlorinating a calcium-containing silicate and/or a magnesium-containing silicate to obtain a calcium chloride and/or magnesium chloride, mixing the calcium chloride and/or magnesium chloride with ammonia water and carbon dioxide and performing a carbonation reaction to recover the carbon dioxide and convert it into calcium carbonate and/or magnesium carbonate while generating an ammonium chloride solution, and recovering the ammonium chloride solution generated in the carbonation reaction. The ammonium chloride solution after being concentrated or hydrogen chloride generated from a decomposition reaction of the ammonium chloride solution is directly used to chlorinate the calcium-containing silicate and/or the magnesium-containing silicate. The ammonium chloride is used as a catalyst for the entire mineralization of the carbon dioxide, the final product is the calcium carbonate and/or the magnesium carbonate.

Abstract: Composition of precipitated calcium carbonate and method of producing the same and the uses of the composition. The composition comprises a plurality of essentially spherical granules having an average diameter of 1-50 um formed from primary precipitated calcium carbonate particles having an average diameter of 30 to 60 nm, capable of liberating at least a part of the primary particles by deagglomeration in aqueous suspension. The present compositions can be used for modifying binders of paints, printing inks, plastics, adhesives, sealants and surface sizes and pulp sizes. The invention further concerns a method for storing of precipitated calcium carbonate particles having an average diameter in the nanometer range.

Abstract: The present invention relates to a calcium carbonate composition for ameliorating, preventing and treating osteoporosis, and a manufacturing method therefor. More specifically, the present invention relates to a calcium carbonate composition for alleviating, preventing and treating osteoporosis, the composition comprising calcium, magnesium and zinc, and having calcium carbonate microparticles formed by the supply of carbon dioxide gas. The present invention provides a composition for maximizing the absorption of calcium, the composition being developed as a health food, food material or the like, and displaying the effects of relieving and alleviating illnesses and symptoms caused by a lack of calcium.

Abstract: Disclosed is a method of preparing calcium carbonate using a direct carbonation reaction. The method includes dissolving fuel gas desulfurization gypsum into an ammonia solution, performing a filtering process after making a carbonation reaction by feeding carbon dioxide into the ammonia solution in which the fuel gas desulfurization gypsum is dissolved, and performing a filtering process after precipitating the calcium carbonate by maintaining a filtered solution in a stationary state.

Abstract: Provided is a method of synthesizing high-purity calcite capable of controlling a grain size thereof, by reacting an aqueous calcium chloride solution with CO2 gas under strong alkaline condition, to crystallize into white and ultra-fine grain calcite. The method of synthesizing fine-grain calcite according to the present disclosure can decrease super-saturation by producing calcite under the strong alkaline conditions, thereby suppressing generation and growth of grain, resulting in controlling the grain size. Therefore, the above method is useful in producing high-purity ultra-fine grain calcite and can control the grain size of calcite from several hundreds of nanometers to several tens of nanometers by regulating the concentration of an aqueous caustic soda solution.

Abstract: Disclosed is a method of preparing calcium carbonate using a direct carbonation reaction. The method includes dissolving fuel gas desulfurization gypsum into an ammonia solution, performing a filtering process after making a carbonation reaction by feeding carbon dioxide into the ammonia solution in which the fuel gas desulfurization gypsum is dissolved, and performing a filtering process after precipitating the calcium carbonate by maintaining a filtered solution in a stationary state.

Abstract: In a method of producing carbonate mineral, a first aqueous solution containing an alkaline earth metal ion extracted from a cation exchange medium by a cation exchange reaction and carbon dioxide are added to a second aqueous solution to form a carbonate mineral.

Abstract: A method including electrolysis processing using sulfate-based electrolytes includes precipitating sodium sulfate decahydrate from a salt solution and then redissolving sodium sulfate decahydrate to prepare feed of electrolyte solution for the electrolysis processing. Front-end processing may be used to treat mixed salt solutions, including brine solutions. Calcium sulfate reagent may provide a sulfate source to regenerate electrolyte solution following carbon capture, and with carbon dioxide being sequestered in the form of calcium carbonate.

Abstract: The present invention discloses a process for producing a nano calcium carbonate slurry from a feedstock of waste gypsum, wherein: an aqueous gypsum slurry of the feedstock is mixed with ammonia water by stirring; with CO2 injected in the slurry is under continuous stirring until the calcium sulfate in the waste gypsum is completely carbonated into nano calcium carbonate; after filtration, the filter cake is dispersed in water to obtain the nano calcium carbonate slurry. This process is easy to operate and to obtain a low-cost and a lower decomposition temperature of calcium carbonate. The present invention also discloses a nano calcium carbonate slurry and its application in preparation of a CaO-based carbon dioxide adsorbent and complex catalyst used for a reactive sorption enhanced reforming process for hydrogen production from methane.

Abstract: Provided is a method for fixing carbon dioxide, the method includding: pulverizing furnace slag; mixing water and the furnace slag such that the furnace slag is present in a concentration of 5˜15 parts by weight based on 100 parts by weight of water; adding NaOH to the mixture; and supplying carbon dioxide to the decomposed mixture, and then carrying out a hydrothermal reaction, so that carbon dioxide can be stably fixed; the treatment of the furnace slag can lead to ecofriendly effects; and the use of the furnace slag can lead to production of carbonate minerals as the final product.

Abstract: A method for capturing carbon dioxide comprising the steps of extracting mineral ions from a mineral source material to a mineral solution by reaction with a first ammonium salt; reacting the mineral solution with a CO2 source to precipitate a carbonate of the mineral and to produce a second ammonium salt; and recovering the first ammonium salt from the second ammonium salt.

Abstract: The present invention relates to an energy efficient carbon dioxide sequestration processes whereby calcium silicate minerals and CO2 are converted into limestone and sand using a two-salt thermolytic process that allows for the cycling of heat and chemicals from one step to another.

Abstract: In some embodiments, the invention provides systems and methods for removing carbon dioxide and/or additional components of waste gas streams, comprising contacting the waste gas stream with an aqueous solution, removing carbon dioxide and/or additional components from the waste gas stream, and containing the carbon dioxide and/or additional components, in one form or another, in a composition. In some embodiments, the composition is a precipitation material comprising carbonates, bicarbonates, or carbonates and bicarbonates. In some embodiments, the composition further comprises carbonate and/or bicarbonate co-products resulting from co-processing SOx, NOx, particulate matter, and/or certain metals. Additional waste streams such as liquid, solid, or multiphasic waste streams may be processed as well.

Abstract: Disclosed herein is a method of producing carbonate, comprising the steps of: providing a water-containing solution including cations that are precipitated in the form of a salt after undergoing a precipitation reaction with carbonate ions; and generating carbon dioxide microbubbles having a diameter of 50 ?m or less in the water-containing solution to induce the precipitation reaction between the cations and the carbonate ions. The method is advantageous in that the carbonate produced using the microbubble system disclosed in the method can be practically used as high-priced building materials, filler for paper manufacturing, etc. and can also be used in foods, medicines and the like depending on the purity thereof, so that it can be recovered in a high yield. Further, the method is advantageous in that carbon dioxide is consumed, and cations can be effectively removed from waste water, so that it is environmentally useful.

Abstract: Provided is a method of synthesizing high-purity calcite capable of controlling a grain size thereof, by reacting an aqueous calcium chloride solution with CO2 gas under strong alkaline condition, to crystallize into white and ultra-fine grain calcite. The method of synthesizing fine-grain calcite according to the present disclosure can decrease super-saturation by producing calcite under the strong alkaline conditions, thereby suppressing generation and growth of grain, resulting in controlling the grain size. Therefore, the above method is useful in producing high-purity ultra-fine grain calcite and can control the grain size of calcite from several hundreds of nanometers to several tens of nanometers by regulating the concentration of an aqueous caustic soda solution.

Abstract: This invention provides aragonite- and calcite-based scaffolds for the repair, regeneration, enhancement of formation or a combination thereof of cartilage and/or bone, which scaffolds comprise at least two phases, wherein each phase differs in terms of its chemical content, or structure, kits comprising the same, processes for producing solid aragonite or calcite scaffolds and methods of use thereof.

Abstract: The present invention relates to an energy efficient carbon dioxide sequestration processes whereby Group 2 silicate minerals and CO2 are converted into limestone and sand using a two-salt thermolytic process that allows for the cycling of heat and chemicals from one step to another.

Abstract: Methods and systems for generating sulfuric acid are disclosed. In some embodiments, the method includes combusting a sulfur-containing material with a gas including oxygen to produce a first stream of sulfur dioxide, mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting the mixed stream of sulfur dioxide and water into sulfuric acid and hydrogen, generating a source of energy from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell for converting the first stream into sulfuric acid and hydrogen, and a fuel cell for generating an energy source from the hydrogen.

Abstract: The present invention relates to carbon dioxide sequestration, including processes in which group-2 silicates are used to remove carbon dioxide from waste streams to form corresponding group-2 carbonates and silica.

Abstract: A method of sequestering a multi-element gas emitted by an industrial plant is described herein, the method comprising: contacting a solution, including a first reactant comprising a multi-element gas emitted by an industrial plant and at least one gas absorber comprising nitrogen, for example ammonia or an amine, with a solid, including a second reactant, under conditions that promote a reaction between the first reactant and the second reactant to provide a first product, which incorporates one or more elements of the multi-element gas, thereby sequestering the multi-element gas.

Abstract: Methods and systems for generating sulfuric acid (102) are disclosed. In some embodiments, the method includes combusting a sulfur-containing material (114) with a gas including oxygen (116) to produce a first stream of sulfur dioxide (118), mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting (108) the mixed stream of sulfur dioxide and water into sulfuric acid (102) and hydrogen (122), generating a source of energy (126) from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell (108) for converting the first stream into sulfuric acid and hydrogen, and a fuel cell (112) for generating an energy source from the hydrogen.

Abstract: Compositions comprising synthetic rock, e.g., aggregate, and methods of producing and using them are provided. The rock, e.g., aggregate, contains CO2 and/or other components of an industrial waste stream. The CO2 may be in the form of divalent cation carbonates, e.g., magnesium and calcium carbonates. Aspects of the invention include contacting a CO2 containing gaseous stream with a water to dissolve CO2, and placing the water under precipitation conditions sufficient to produce a carbonate containing precipitate product, e.g., a divalent cation carbonate.

Abstract: The present invention relates to a process for the recovery of elemental sulphur from residues produced in hydrometallurgical processes based on leaching with a solution of sodium sulphide in which the sulphur contained in the residues is selectively leached as sodium polysulphide. The sulphur leaching solution is conveniently regenerated and recycled to the process.

Abstract: Methods and systems for generating sulfuric acid (102) are disclosed. In some embodiments, the method includes combusting a sulfur-containing material (114) with a gas including oxygen (116) to produce a first stream of sulfur dioxide (118), mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting (108) the mixed stream of sulfur dioxide and water into sulfuric acid (102) and hydrogen (122), generating a source of energy (126) from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell (108) for converting the first stream into sulfuric acid and hydrogen, and a fuel cell (112) for generating an energy source from the hydrogen.

Abstract: To provide a process for producing carbonate particles, capable of efficient, easy formation of carbonate particles which have high crystallinity, less prone to agglomeration and offer orientation birefringence, particularly carbonate particles that are needle- or rod-shaped, and of controlling the particle size. In the process a metal ion source and a carbonate ion source are heated together in a liquid of 55° C. or higher for reaction to produce carbonate particles with an aspect ratio of greater than 1, wherein the metal ion source contains at least one metal ion selected from the group consisting of Sr2+, Ca2+, Ba2+, Zn2+ and Pb2+. The carbonate particles are preferably needle- or rod-shaped, pH of the liquid after heating reaction is preferably 8.20 or more, and in its X-ray diffraction spectrum the full-width at half maximum of the diffraction peak corresponding to (111) plane is preferably less than 0.8°.

Abstract: The invention discloses methods for making micron/nano meter sized particles of various inorganic materials such as minerals/oxides/sulphides/metals/ceramics at a steadily expanding liquid-liquid interface populated by suitable surfactant molecules that spontaneously organize themselves into superstructures varying over large length-scales. This experiment is realized in a radial Hele-Shaw cell where the liquid-liquid interfacial growth rate and consequently time scales such as arrival of surfactant molecules to the interface, the hydrodynamic flow effect to modulate the material organization into super structures at the dynamic charged interface.

Abstract: The present invention discloses a process for producing nano-powders and powders of nano-particle loose aggregate, which includes: (a) providing at least two reactant solutions A and B capable of rapidly reacting to form deposits; (b) supplying the at least two reactant solutions A and B at least at the reaction temperature into a mixing and reaction precipitator respectively, in which mixing reaction and precipitation are continuously carried out in sequence, the mixing and reaction precipitator being selected from at least one of a tubular ejection mixing reactor, a tubular static mixing reactor and an atomization mixing reactor; and (c) treating the deposit-containing slurry continuously discharged from the mixing reaction precipitator.

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. Herein disclosed is a process for producing calcium carbonate in the form of aragonite crystals which is useful as a filler for papermaking via the causticization step of the sulfate or soda pulping process, comprising adding an aqueous alkaline solution having a hydroxide ion level of 3 mol/l or less and containing 0.25 mol or less of carbonate ion per 1 mol of quick lime to quick lime and/or slaked lime at a quick lime concentration of 1–60% by weight with stirring to prepare milk of lime, and then adding green liquor to said milk of liquor at a loading rate of 0.002–0.12 g (sodium carbonate)/min/g (quick lime) to perform a causticization reaction at a temperature of 30–105° C.

Abstract: Titanium dioxide-calcium carbonate composite particles capable of realizing characteristic properties inherent in titanium dioxide such as a high opacity, a process for producing the same, and a complex composition or complex incorporated with the same are provided. The composite particles were prepared by adding titanium dioxide particles having an average particle diameter of 0.1 to 0.5 ?m in a carbonation step, typically a step of introducing a gaseous mixture of carbon dioxide and air into a calcium hydroxide slurry with stirring, to conduct a carbonation, and continuing the reaction till pH of the slurry becomes 7 by continuous introduction of the gaseous mixture. Moreover, by incorporating the formed composite particles, complexes such as coatings and paints for paper making or composite materials such as paper, plastic molded materials, and rubber molded materials are produced.

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: The present invention provides an electrochemical process for reducing metal contaminants in calcium carbonate by solubilizing the metal contaminate in an aqueous solution of calcium carbonate and then removing the solubilized metal contaminant by passing an electrical current through the aqueous calcium carbonate solution containing the solubilized metal contaminant. Calcium carbonate produced according to the process of this invention is particularly suitable for use as food or pharmaceutical additives. The calcium carbonate is also suitable for use in papermaking process as fillers, or coatings, or as additives in the production of plastics, paints and adhesive products. Other uses of high purity calcium carbonate include catalysts and catalyst supports, electrical/semiconductor applications, florescent lighting, and optical/laser applications.

Abstract: This invention relates to a low energy hydrometallurgical process for the production of strontium carbonate of chemical and glass grade from carbonate rich celestite ores typically having around 28% combined strontianite, calcite, dolomite and other carbonates. This process avoids negative environmental impact usually associated to calcining technology and involves fewer processing stages than prior art hydrometallurgical processes. Thus, in two stages which provide: (1) the acid wash of the celestite ore in an acid medium to eliminate carbonates present other than strontium carbonates and (2) the conversion of the thus enriched celestite to strontium carbonate in an air/vapor-lift loop reactor using a sodium carbonate aqueous medium, a step permitting recovery of sodium sulfate as a by-product. Thus, an almost complete conversion of the strontium sulfate present in the enriched ore is achieved.

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: A method for the manufacture of precipitated calcium carbonate from impure calcium oxide of improved colour 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 separated from insoluble matter and then treated with carbon dioxide or the carbonate of the amine or alkanolamine. 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: 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 process for producing ultrafine particles of colloidal calcium carbonate which comprises the steps of adding magnesium sulfate into an aqueous suspension of calcium hydroxide, carbonating the aqueous suspension by introducing carbon dioxide into the aqueous suspension, and adding zinc sulfate alone or together with sulfuric acid into the aqueous suspension simultaneously with the carbonation step. Ultrafine particles of colloidal calcium carbonate in a chain-structured configuration which have an average diameter of 0.01 .mu.m or smaller, an average length of 0.05 .mu.m or longer, and a BET surface area of 70 m.sup.2 /g or greater are produced.

Abstract: The high temperature combustion of hydrogen and oxygen is used to transform halogenated refrigerant gases (HRGs) and halons to produce calcium fluoride salts. Calcium carbonate is also produced by a series of chemical processes. Calcium chloride is partially consumed by the process by reaction with fluoride released during the high temperature combustion of the HRGs. Calcium chloride is also produced in the process during scrubbing of chlorine and during the recovery of ammonia used to remove carbon dioxide. The calcium chloride produced during the process can be used in the combustion reaction to further produce calcium fluoride.

Abstract: A process for the removal and recovery of ammonia from liquid waste, characterized essentially by the following operations:reacting the liquid waste with pure carbon dioxide, or with a gaseous mixture rich in carbon dioxide, or with at least one carbonate, to give ammonium carbonatereacting the resulting ammonium carbonate with calcium chloride to give calcium carbonate and ammonium chloride;causing the resulting calcium carbonate to undergo thermal decomposition to give calcium oxide and carbon dioxide;using, optionally, the carbon dioxide formed after thermal decomposition of calcium carbonate for said reaction with the liquid waste; andusing the calcium oxide, formed after thermal decomposition of calcium carbonate, for the production of pure ammonia, by reaction with the ammonium chloride obtained in said reaction between ammonium carbonate and calcium chloride.The figure shows a flow sheet of a plant allowing the operations of an embodiment of the above process.

Abstract: A method for producing an anion intercalated hydrotalcite without first forming hydrotalcite and then having to activate the hydrotalcite prior to substituting anions in the hydrotalcite structure. The method includes reacting an activated magnesia with an aqueous solution of aluminate, anion, such as bromide, chloride, sulfate, borate and combinations thereof and hydroxyl ions. The method can be carried out at atmospheric pressure to form hydrotalcite in high purity and high yield. In a preferred embodiment of the invention, the aluminate solution is formed from sodium aluminate, sodium bromide and sodium hydroxide and the aqueous solution is substantially carbonate free. Other anion intercalated hydrotalcites can also be produced by the method of the present invention.

Abstract: A method is disclosed for producing barium carbonate by adding barium sulfate to coal tar pitch maintained at a temperature of about 350.degree. C. to about 450.degree. C., and thereafter heating the reactants to a temperature between 700.degree. C. to 950.degree. C. in a second stage. The second stage reaction product is reacted with an alkali metal carbonate.

Abstract: Disclosed is a novel basic magnesium carbonate represented by the following general formula:nMgCO.sub.3.Mg(OH).sub.2.mH.sub.2 Owherein n is a number of from 3 to 5 and m is a number of from 3 to 5,which consists of porous particles composed of an aggregate of plate crystals having an average particle size of 1 to 50 .mu.m and a specific surface area of 10 to 70 m.sup.2 /g, wherein in the fine pore size distribution of the particles, the volume of fine pores having a radius smaller than 100 .ANG. is at least 0.02 cc/g and the volume of fine pores having a radius smaller than 75,000 .ANG. is at least 0.8 cc/g.This novel basic magnesium carbonate is highly improved over conventional basic magnesium carbonate in such properties as filling property, dispersibility and flowability.

Abstract: The processing of leaching residues from barium sulfide leaching is described. Sodium sulfide as well as a solid which is useful as an additive for fired clay products, particularly bricks, are obtained as valuable reaction products.

Abstract: In the manufacture of ammonium paratungstate, sulfide is added to a tungsten-containing solution in order to precipitate molybdenum sulfide. Volatiles, including sulfides, evolved during this process are collected in a caustic scrubbing solution. The sulfide values in the caustic scrubbing solution may be reused to precipitate molybdenum sulfide by first treating the caustic scrubbing solution with alkaline earth chloride or sulfate to precipitate out alkaline earth carbonate.

Abstract: A means for promoting the neutralization reaction between particulate calcium carbonate and ionized phosphate by adding a material formed by the reaction of particulate calcium carbonate and dilute hydrofluoric acid. The products of this invention are useful in lowering serum phosphate levels in patients undergoing renal dialysis, and are also useful as antacids. These products are also useful in the treatment of water and waste water to lower phosphate content.

Abstract: High purity magnesium oxide is obtained from a magnesite-containing ore, the impurities of which include calcium compounds. The ore is first calcined and the resulting magnesium oxide is converted to magnesium chloride by leaching with an ammonium chloride solution. Calcium chloride is also produced at the same time. The resulting magnesium chloride and calcium chloride are treated with carbon dioxide to form calcium carbonate and magnesium carbonate which can be precipitated and filtered out of the resulting magnesium chloride solution. The magnesium chloride solution is then reacted with ammonium carbonate to produce a magnesium carbonate trihydrate crystal slurry containing ammonium chloride. The ammonium chloride is subsequently removed and returned to the ammonia recovery stage for leaching of the calcined magnesium oxide while the crystals are dried and decomposed into carbon dioxide and magnesium oxide.

Abstract: Process for the recovery of valuable metals, particularly rare earths and similar metals, which occur in a finely distributed condition in a raw material containing calcium carbonate.The raw material with the valuable elements is subjected to vigorous heating to decompose calcium carbonate and is allowed to react with sulphur oxides, particularly SO.sub.2, so that the calcium present is converted to insoluble calcium sulphate. The valuable metals are extracted from the calcine by extraction with dilute acid or water, whereafter the valuable metals are recovered from the extract in a per se known manner.The heating and the reaction with sulphur oxides may be carried out by mixing the raw material containing the valuable elements with sulphur or a combustible sulphurous material, such as pyrite, and subjecting it to exothermic combustion.

Abstract: Essentially pure strontium carbonate is recovered from low to medium grade strontium sulfate containing ores by first treating the ore with a hydrochloric acid solution to remove extraneous materials including calcium, magnesium, barium, and iron. The remaining strontium sulfate containing residue is treated with ammonium carbonate to produce insoluble strontium carbonate and soluble ammonium sulfate. The strontium carbonate then is converted to soluble strontium chloride through treatment with a second, stronger hydrochloric acid solution. Any remaining extraneous barium or iron is removed from the second acid solution before the strontium chloride is reconverted to insoluble strontium carbonate and precipitated out of solution for recovery.

Abstract: The invention provides particulate calcium carbonate having incorporated therein from 0.1 to 10% by weight, based on the weight of calcium carbonate, of polymaleic acid or a water-soluble salt thereof.

Abstract: Crystalline, basic magnesium aluminum hydroxycarbonate of the formulaAl.sub.2 Mg.sub.6 (OH).sub.12 (CO.sub.3).sub.3.xH.sub.2 Owhere x is at least 4. A process for producing it comprises the conversion of aluminum hydroxide with basic magnesium carbonate and at least one compound selected from magnesium hydroxide and magnesium oxide. Stoichiometric quantities are employed with reference to the aluminum and the magnesium. The conversion takes place at temperatures from 50.degree. to 100.degree. C., and the resulting product is subsequently spray dried.