Abstract: A process for the preparation of magnesium compounds from breunnerite or from mineral concentrates or tailings containing breunnerite in which the mineral is calcined and treated with an acid and the magnesium salt solution so formed is separated from insoluble matter.

Abstract: An improved method of preparing magnesium chloride in which magnesium oxide, hydroxide or carbonate or a material containing magnesium oxide is caused to react with waste chlorides produced in the manufacture of titanium tetrachloride and the solution of magnesium chloride so formed is separated from insoluble matter.

Abstract: A method of beneficiating a mixed salt mineral ore containing potassium and magnesium sulfates and/or their hydrates which allows the recovery of anhydrous magnesium chloride and the simultaneous recovery of commercially acceptable potassium sulfate.

Abstract: Calcium fluoride is produced from pond waters resulting from phosphoric acid processing by treating the pond waters with calcium carbonate and/or calcium oxide in two stages to precipitate out the major part of the fluorine values from the waters as calcium fluoride. After removal of the calcium fluoride the filtrate is treated with calcium oxide to remove a substantial portion of the remaining fluorine values as calcium fluoride. After removal of these calcium fluoride solids, the filtrate is treated with another charge of calcium oxide to produce dicalcium phosphate (dical) which is separated from the aqueous phase. The aqueous phase is treated with an additional charge of calcium oxide to remove a substantial portion of the solids from the aqueous phase leaving waters that can be discharged as waste or recycled as process water.

Abstract: A process for purifying waste water containing fluoride which comprises precipitating fluoride from the waste water as fluorapatite. Fluoride is removed as fluorapatite by having sufficient available calcium for each mole of fluoride present in the waste water and sufficient available phosphate for each mole of fluoride in the waste water to form a precipitate which is or converts to sufficient fluorapatite to remove essentially all fluoride from the waste water.

Abstract: The present invention relates to a process for the production of potassium chloride and of magnesium chloride hexahydrate (bischoffite) from carnallite or from carnallite containing sodium chloride.The process comprises heating carnallite at a temperature of between above 70.degree. C. and above 167.5.degree. C. in the presence of added water at the above former temperature or without added water (but preventing evaporation of water) at the above latter temperature. Solid potassium chloride is then separated. In the residual brine, carnallite is precipitated by evaporation or by lowering the temperature, and it is recycled to the starting stage. The residual solution consists essentially of magnesium chloride which is recovered as bischoffite.

Abstract: Metal ion impurities are removed from phosphoric acid by adding to the acid a precipitant comprising ions of calcium and fluorine to cause precipitation of a fluoride solid which contains ions of magnesium, and other metals (e.g., Al, N.sub.a) which were in the impure acid. A preferred precipitant comprises calcium fluoride, such as the sludge obtained by treating pond water from a phosphoric acid plant with calcium ions (e.g. lime and/or limestone).

Abstract: A process for the manufacture of calcium sulphate alpha-hemihydrate which comprises the step of interacting an aqueous solution of calcium chloride and a source of sulphate or bisulphate ions in an aqueous system at a temperature above the calcium sulphate hemihydrate/gypsum transition temperature under the reaction conditions. The preferred reagents are the waste calcium chloride/sodium chloride effluent of the ammonia soda process and sulphuric acid (e.g. impure sulphuric acid effluent) to give hydrochloric acid as a co-product. The preferred reaction temperature is at least 20.degree. C. above the transition temperature (about 70.degree. C), e.g. at 95.degree.-100.degree. C at atmospheric pressure.

Abstract: Concentrated magnesium chloride solutions are prepared from industrial liquors or brines by debrominating the liquor with chlorine, neutralizing the debrominated liquor up to a ph value of 3-6, adding a stoichiometric excess of calcium chloride to the neutralized liquor at temperatures in the range of 30.degree.-50.degree. C to form a calcium sulfate dehydrate crystallizate, separating the crystallizate from the mother liquor, adding a sufficient amount of carnallite to the mother liquor to increase the MgCl.sub.2 content thereof to 270-330 g/l after cold decomposition of the added carnallite and concentrating the resulting solution in two or more steps in the direct current in an evaporator with crystallization characteristics up to a final concentration of 440 to 470 g/l MgCl.sub.2 whereafter the concentrated magnesium chloride solution is separated from crude crystallized carnallite and sodium chloride formed during the concentration.

Abstract: In an industrial process of preparing high-purity magnesia from an impure magnesium-containing starting material, wherein the starting material is dissolved in HCl and the resultant acidic solution is subjected to a multistep treatment for precipitating the impurities out of the solution, the precipitate is separated from the residual purified magnesium chloride solution, and the magnesium chloride is thermally decomposed to obtain magnesia, the purified magnesium chloride solution is first concentrated and sulfate ions are then added thereto to precipitate calcium ions from the concentrated solution as calcium sulfate.

Abstract: Magnesia of very high purity is produced industrially from a magnesite waste material wherein impurities are present in such amounts that the weight ratio of the precipitable hydroxide ions, calculated as the sum of Fe.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + Cr.sub.2 O.sub.3 + Mn.sub.3 O.sub.4 to the sum of SiO.sub.2 + TiO.sub.2 + B.sub.2 O.sub.3, is at least 1 : 3. The starting material is dissolved in hydrochloric acid of 15-32% concentration, the impurities are precipitated by adjusting the pH of the acidic solution to 4 - 9, and the purified magnesium chloride solution is thermally decomposed into magnesia and hydrochloric acid gas, the latter being recycled to form the hydrochloric acid of the stated concentration for dissolving the starting material.

Abstract: A continuous process for the manufacture of calcium hypochlorite in which an aqueous slurry of lime and sodium hypochlorite is chlorinated in a mixing zone to form a sodium chloride solution containing large crystals of calcium hypochlorite which are readily separated and dried. The resulting solution containing some dissolved calcium hypochlorite is reacted with an alkali metal hydroxide to precipitate lime, which is separated and recycled to the mixing zone slurry. The lime-free solution may be used as bleach liquor or processed to precipitate solid salt useful in the preparation of brine. The remaining solution is recycled to the mixing zone slurry. Purification of fresh lime is also disclosed.The process provides an improved separation of calcium hypochlorite and sodium chloride, and recycles all solutions to minimize pollution of water resources.