Abstract: The present invention provides a process for producing potassium sulfate from a potash and a sodium sulfate source, comprising the steps of: (a) treating a portion of the potash source and sodium sulfate source, such that glaserite is crystallized out of solution and a first mother liquor is produced; (b) converting the glaserite to precipitate potassium sulfate in a second mother liquor; (c) recycling the second mother liquor to the portion of the potash source and sodium sulfate source; (d) subjecting the first mother liquor to evaporative crystallization to produce sodium chloride in a third mother liquor; and (e) recycling the third mother liquor to the portion of the potash source and sodium sulfate source.

Abstract: The specification discloses an apparatus and method for treating a slurry containing sodium sesquisulfate to recover sulfate and acid constituents therefrom. The apparatus includes a treatment vessel having a separation wall delineating a clarifying zone and a mixing zone. Slurry containing sesquisulfate crystals is introduced into the mixing zone along with water and the material is mixed to promote dissolution of the crystals and formation of sodium sulfate solids. Sodium sulfate solids are collected in a lower portion of the treatment vessel and conveyed out of the vessel, and liquid from the clarifying zone is conducted from an upper end of the treatment vessel to a conventional liquid processing unit. Treatment of a sesquisulfate-containing slurry in accordance with the invention provides sodium sulfate containing little or no sesquisulfate crystals thereby reducing the need for vacuum filtration or other expensive separation techniques to recover sulfuric acid and sodium sulfate solids from the slurry.

Abstract: The invention relates to a process for the preparation of crystalline sodium silicates having a sheet structure and high .delta. phase content from water glass, which has been prepared hydrothermally, by dehydration of the water glass and subsequent crystallization at elevated temperature, which comprises treating the water glass at temperatures of from 50 to 140.degree. C. prior to dehydration.

Abstract: The invention relates to a process for the preparation of crystalline sodium silicates having a sheet structure and high .delta. phase content from water glass, which has been prepared predominantly hydrothermally, by dehydration of the water glass and subsequent crystallization at elevated temperature, wherein the water glass is a mixture of water glass prepared hydrothermally and tank furnace water glass, and also to its use.

Abstract: Lithium carbonate can be efficiently produced from a brine by (i) removing the boron therefrom, (ii) diluting the boron-free brine, (iii) removing magnesium from the diluted brine, and (iv) adding sodium carbonate to thereby precipitate lithium carbonate. By diluting the boron-free brine, the co-precipitation of lithium carbonate during the magnesium removal process is greatly reduced, thereby improving the recovery and purity of the lithium carbonate.

Abstract: A process is provided for making K.sub.2 SO.sub.4 3Al.sub.2 O.sub.3 4S0.sub.3 +xH.sub.2 O or Na.sub.2 SO.sub.4 3Al.sub.2 O.sub.3 4SO.sub.3 +xH.sub.2 O where x is a number from 4 to 12, which is used as a pigment. Sulfuric acid, one of a sulfate salt or a hydroxide of either potassium or sodium and one of a sulfate of aluminum or a hydroxide of aluminum are inputted into a crystallizer and reacted to form either Al.sub.2 (SO.sub.4).sub.3 K.sub.2 SO.sub.4 +24H.sub.2 O or Al.sub.2 (SO.sub.4).sub.3 Na.sub.2 SO.sub.4 +24H.sub.2 O. A fluid flow containing either Al.sub.2 (SO.sub.4).sub.3 K.sub.2 SO.sub.4 +24H.sub.2 O or Al.sub.2 (SO.sub.4).sub.3 Na.sub.2 SO.sub.4 +24H.sub.2 O is drawn off from the crystallizer and transferred into a pigment reactor where it is subjected to a temperature of about 200.degree. C. and a pressure ranging from 120 to 350 pounds per square inch so as to result in the production of either basic potassium aluminum sulfate K.sub.2 SO.sub.4 3Al.sub.2 O.sub.3 4SO.sub.3 +xH.sub.

Abstract: A process for making ink which begins with a leach liquor of Al.sub.2 (SO.sub.4).sub.3 +K.sub.2 SO.sub.4 +Fe.sub.2 SO.sub.4 and other sulfates that are introduced to a surface-cooled crystallizer that drops the Al.sub.2 (SO.sub.4).sub.3 +18H.sub.2 O which is removed from the leach liquor. The leach liquor is then supplied with a mixture which includes K.sub.2 SO.sub.4 into a simple crystallization and evaporation unit to drop Al.sub.2 (SO.sub.4).sub.3 +K.sub.2 SO.sub.4 +24H.sub.2 O. A pressure of 250 PSI and a temperature of 200.degree. C. are then applied in a discrete continuous process that yield a basic sodium or sodium/potassium aluminum sulfate and excess sodium sulfate or sodium/potassium. The excess sodium sulfate or sodium/potassium sulfate is returned to the simple crystallization and evaporation unit. The basic potassium aluminum sulfate (BKAS) and/or basic sodium aluminum sulfate (BNaAS) Na.sub.2 SO.sub.4, 3Al.sub.2 O.sub.3, 4SO.sub.3, 9H.sub.2 O is used as a filler in the making of ink.

Abstract: A process for the preparation of anhydrous sodium from a thenardite ore containing sodium sulfate comprising the steps of: crushing the thenardite ore; lixiviating the crushed ore in a first lixiviation step with water or with an exhausted solution from a succeeding step, at a temperature between about 28.degree. C. and 40.degree. C., obtaining a suspension comprising a sodium sulfate saturated solution, sludges and insoluble material, settling the sludges and insoluble material from the saturated solution to separate a clarified solution; crystallizing the clarified saturated solution in a first crystallization step at a temperature between 32.degree. C. and 20.degree. C., maintaining the height of the solution not exceeding about 15 centimeters, to obtain a Glauber salt with large crystals of sodium sulfate and ten molecules of water. When the clarified saturated solution is crystallized, an exhausted solution is produced which is drained and recycled back to the first lixiviation step.

Abstract: In order to recover in an environmentally sound and economic manner used hardening shop salts which contain nitrate-nitrite, the salts, comminuted to particle sizes of from 1 to 50 mm, are dissolved in a mixture of nitric acid and hydrogen peroxide without nitrogen oxides arising, and, by evaporation and cooling, potassium nitrate, sodium chloride, and sodium nitrate are obtained sequentially by fractional crystallization.

Abstract: This invention relates to a process for removing sodium chloride and potassium salts, which are impurities concentrated and accumulated in pulp digesting chemicals, from ash collected from a soda recovery boiler. This process comprises the steps of (a) mixing ash collected from the combustion exhaust gas of the soda recovery boiler with water to form a slurry, adjusting the pH of the slurry to 10 or less by the addition of sulfuric acid, adjusting the temperature of the slurry to 20.degree. C. or above, and holding the slurry at that temperature for a sufficient time to cause sodium chloride and potassium salts present in the collected ash to be dissolved in the water; (b) cooling the slurry to a temperature below 20.degree. C. by the addition of ice and/or water so as to precipitate solid matter therefrom; and (c) separating the slurry into solid and liquid components and recovering the solid component while discharging the liquid component out of the system.

Abstract: The process for environmentally acceptable and economical recovery of chloride salts from hardening-shop used salts utilizing the steps of leaching of the used salt, detoxification of the cyanide and selective crystallization of the individual chloride salts. The process is characterized in that all the chloride salts that are present in the hardening-shop used salt are recovered in pure form.

Abstract: Mineral salts, e.g., potassium chloride, are crystallized from aqueous solutions thereof in the presence of a crystal growth promoting amount of lecithin or lecithin containing compositions. Mineral salts include alkali metal and alkaline-earth metal chloride, sulfate, carbonate, phosphate and nitrate salts. The process is described as providing increased amounts of large crystals and a narrower and more uniform crystal size distribution.

Abstract: Continuous process for the manufacture of solid alkali metal persalt particles coated by crystallization of a supersaturated aqueous solution of persalts and covering of the persalt particles in a post-crystallization vessel into which at least one coating agent is introduced and in which crystallization of the coating agent around the persalt particles is carried out under controlled temperature and stirring conditions.

Abstract: New alkali metal cyanide granulates based on sodium cyanide or potassium cyanide and a method for their preparation are disclosed. Commercially available alkali metal cyanide granulates consist of irregular particles; disadvantages are in particular the tendencies to form dust and to cake. The disclosed alkali metal cyanide granulates demonstrate a reduced tendency to cake and virtually no abrasion. The granulates are characterized by essentially spherical particles with particle diameters in the range 0.1 to 20 mm, a bulk density of more than 600 g/dm.sup.3, an abrasion of less than 1%, and a caking index of at most 4. The granulates can be prepared by fluidized bed spray granulation involving spraying an aqueous solution containing alkali metal cyanide onto alkali metal cyanide nuclei in a fluidized bed and evaporating the water.

Abstract: A low bulk density hollow fine powder of alkali metal compound can be produced from an aqueous solution of the compound by one step. The method for producing a low bulk density hollow fine powder of alkali metal compound according to the present invention comprises a step of contacting an aqueous solution of an alkali metal compound with a pulsating combustion gas.

Abstract: A potassium chloride mixture with grains of different sizes is extracted in a first stage with an unsaturated solution at an elevated temperature, whereby the finest grains are completely dissolved and the coarse proportions are caused to start dissolution, the purified medium fraction is transported into a second process stage and the previously dissolved amount of KCl is crystallized there onto the purified grains at a lower temperature, forming a product of high purity with a balanced grain size and a narrow grain spectrum.

Abstract: A method and apparatus are provided for superpurifying crystallizable substances to a purity level of 99.999%. Included is a closed multistage system which maintains controlled transfers of material between a plurality of stages. The method and apparatus avoid the need to transfer solid crystals from one stage to another and effect efficient and very effective separation of purified crystals from their mother liquor.

Abstract: A method for producing potassium carbonate using a continuous countercurrent exchange system. A continuous ion exchange system with resin in the ammonium form is flushed with a saturated potassium chloride solution which displaces the ammonium ion and replaces it with potassium. Ammonium carbonate is then passed through the ion exchanger to place the ammonium in the reserve form, by displacing the potassium, and produce a concentrated potassium carbonate solution. This process is done in a continuous countercurrent manner which allows maximum recovery of the potassium carbonate as a 15-18% by weight solution with minimum impurities, and at high throughput rates. The potassium carbonate solution is then removed, evaporated, dried, sized and stored for subsequent shipment.

Abstract: A large size, small surface area, granular crystalline potassium bicarbonate product suitable for application as an active ingredient in pharmaceutical oral unit dosage forms useful for the treatment of various degenerative bone and cardiovascular diseases, particularly osteoporosis or hypertension, comprising potassium bicarbonate crystals having a mean particle size of at least 350 microns and a specific B.E.T. surface area less than 0.02 m.sup.2 /gram. A process for preparing such product is further provided, in which a solution of potassium bicarbonate is fed to a slurry of potassium bicarbonate crystals in a crystallizer and the temperatures and concentrations of the potassium bicarbonate in the feed solution and the crystallizer slurry are so regulated, and the residence time and degree of agitation in the crystallizer are so controlled, that the desired large size, small surface area potassium bicarbonate crystals are produced.

Abstract: A process for removing perchlorate ion from waste water using KCl is disclosed. In the process, waste perchlorate is concentrated by water evaporation in a stripping tower. Ammonia and volatile organics are removed during the concentrating step. Potassium chloride (KCl) is added to the concentrated perchlorate solution to form potassium perchlorate (KClO.sub.4), and the reaction mixture is cooled to effect crystallization of the potassium perchlorate. The crystallization liquor is removed by centrifuge or filter press and may be further treated as part of an overall waste water treatment system.

Abstract: The average size of ammonium sulfate crystals is increased by passing undersized ammonium sulfate crystals through a multistage apparatus in which the crystals are contacted with an aqueous ammonium sulfate spray in a first heated chamber to increase the average size of the crystals, the enlarged crystals thereafter passing through a second heated chamber to dry the enlarged crystals.

Abstract: A method of reducing soluble and insoluble impurity levels while increasing the size of water soluble salt crystals which includes an initial step of fine grinding followed by regrowth in a saturated solution of the salt subjected to agitation.

Abstract: A multistage process for the separation and purification of a desired crystalline material by repeated dissolution and recrystallization, wherein crystals and solvent move countercurrent to one another through the stages. A fluid temperature gradient is maintained within each recrystallization unit to make use of convection to facilitate or accelerate concurrent dissolution and recrystallization within a single vessel. Solid recrystallized material is moved from one unit to the next unit. An automated apparatus and a manually operated apparatus for carrying out the process are also described.

Abstract: A process for recovery of metallic aluminum, sodium and potassium chloride and an aluminum oxide-metallic aluminum product from secondary aluminum dross. A secondary aluminum dross feed is separated by particle size into a first dross portion which is water leached, filtered, evaporated in an evaporator to produce crystallized sodium and potassium chloride salts, magnesium chloride remaining in solution. A purge stream is removed from the evaporator wherein the crystallized salts are separated therefrom. The purge stream is then discharged onto the crystallized salts.

Abstract: A process for the recovery of metallic aluminum, mixtures of salts, and an aluminum oxide-metallic aluminum product from secondary aluminum dross. The process includes treating the dross with leach water to dissolve the salt content. Magnesium chloride is preferably added to the leach water to maintain the pH in the range of about 7-8.5, thereby reducing ammonia production in the treating step and enhancing recovery of metallic aluminum.

Abstract: This invention relates to methods and systems for purifying brine for electrolysis in chlor-alkali cells, especially membrane cells by reducing the sulfate ion concentration, while at the same time minimizing the concentration of other undesireable ions such as calcium and chlorate. The methods and systems employed are unique combinations of refrigeration and crystalization, and brine recirculation techniques in the systems for electrolyzing brine.

Abstract: Crystals are grown in a tank which is divided by a baffle into a crystal growth region above the baffle and a plenum region below the baffle. A turbine blade or stirring wheel is positioned in a turbine tube which extends through the baffle to generate a flow of solution from the crystal growing region to the plenum region. The solution is pressurized as it flows into the plenum region. The pressurized solution flows back to the crystal growing region through return flow tubes extending through the baffle. Growing crystals are positioned near the ends of the return flow tubes to receive a direct flow of solution.

Abstract: A crystal is grown in a constantly filtered solution which is flowed directly into the growing face of a crystal. In a continuous flow system, solution at its saturation temperature is removed from a crystal growth tank, heated above its saturation temperature, filtered, cooled back to its saturation temperature, and returned to the tank.

Abstract: Potassium chloride crystals of larger and/or more regular size are produced by conducting the crystallization in the presence of a small amount of a branched C.sub.12 monoalkylated diphenyl ether sulfonate or a linear C.sub.6 alkylated diphenylether sulfonate.

Abstract: Disclosed is a flow-through sodium chloride crystallizer comprised of a vertically-oriented crystallizer body having at least two segments of different cross-sectional area, at least two inlets for the introduction of saturated MgCl.sub.2 brine at minimum of two distinct vertical locations having different cross-sectional areas along the crystallizer body, at least two inlets for the introduction of a saturated NaCl brine at a minimum of two distinct vertical locations having different cross-sectional areas along the crystallizer body, at least one lower outlet for removal of NaCl crystals and at least one upper outlet for removal of spent brine. Also disclosed is an apparatus for producing hopper-shaped NaCl crystals and/or NaCl crystals of varying, segregated purity, and a process for producing the same.

Abstract: The removal of fluoride ion from potassium chloride containing at least a small amount of an acidic component with water is improved by adjusting the pH of the aqueous solution employed in a fractional crystallization of between about pH6 and about pH9 or adjusting the pH of the extractant used in an aqueous extraction by adding an amount of base so that final pH of the the extract is between about pH6 and about pH9. The fluoride ion contamination of potassium chloride, for example, was reduced from 1000 ppm to 90 ppm by adjusting the aqueous solution employed in a recrystallization of pH6.5 before precipitation.

Abstract: A process for manufacturing, shipping and unloading substantially solid, ice-like sodium cyanide dihydrate containing essentially no liquid water. A slurry of 58 weight percent or higher sodium cyanide is rapidly cooled to the anhydrous/dihydrate transition temperature while minimizing the settling out of sodium cyanide crystals to form the product in a container. Dissolution prior to unloading is by adding heat and water or dilute sodium cyanide solution.

Abstract: An improved process for the manufacture of sodium metabisulfite is provided. In this process, the chemical reaction forming sodium bisulfite solution is carried out separately from the crystallization of sodium metabisulfite. The crystallization step is carried out without chemical alteration and without pH adjustment.

Abstract: A process for treating potassium chloride, wherein the potassium chloride is dissolved in an aqueous medium and resulting solution is heated to evaporate water contained therein.

Abstract: An improved process is described for recovering lithium from evaporatively concentrated brines. Epsom salt recovered from the brine at about 0.degree. C. is added to the concentrated lithium-containing brine, so as to precipitate lithium sulfate monohydrate, the brine having previously been subjected to the sequential steps of two stage chilling, evaporative concentration, further chilling and vacuum evaporation.

Abstract: The invention concerns a process for the precipitation of aluminium hydroxide by seeding in two phases, which is intended to produce at a high level of productivity alumina with large grains, referred to as `sandy coarse`, by precipitation in a succession of tanks in cascade relationship of a supersaturated solution of sodium aluminate coming from alkaline attack on bauxite in accordance with the BAYER process. The process comprises three stages:in the first agglomeration stage, the supersaturated aluminate liquor is introduce into the tank, with an equivalent amount of terms of Na.sub.2 O of between 110 and 175 g/liter, at a temperature of between 65.degree. and 80.degree. C.

Abstract: Brine containing at least two salts, one or more of the salts having a higher hydrated form and a lower hydrated or anhydrous form, is fed to a non-convective solar pond and one of the salts having a higher hydrated form and a lower hydrated or anhydrous form is crystallized in a higher hydrated form, dehydrated to a lower hydrated form, and recovered from the bottom of the pond in solid, pure form essentially free from the other salts in the brine. To effect separation, the salt having a higher hydrated form and a lower hydrated or anhydrous form, which is to be recovered in pure form must be present in the pond in an essentially saturated concentration. The concentrations of any of the other salts must generally not exceed saturation concentration at the temperature in the top layer of the pond, and must not exceed saturation concentration at the conditions in the bottom layer of the pond. Concentrations of other salts in the pond must be controlled such that the required density gradient is maintained.

Abstract: In a process of producing coarse pure potassium chloride crystals from feed solutions containing potassium chloride and other impurities, comprising cooling the solution under a vacuum in a plurality of stages connected in series, withdrawing by means of a conveyor the potassium chloride which has been crystallized in each stage, withdrawing the water vapors, collecting crystalline potassium chloride from the solution, drying the crystalline potassium chloride and separating the same into several fractions, compacting the fine fraction and cooling and aminating the end product, the potassium chloride content of the feed solution is increased in that potassium chloride from one or more of the stages containing solution at a low temperature is recycled to the feed solution before the latter enters the first stage.

Abstract: An improved process for the production of potassium sulfate crystals by the reaction of saturated solution of potassium chloride with langbeinite in the solid phase at a temperature of from 45.degree.-55.degree. C., thereby forming potassium sulfate crystals and magnesium chloride solution comprising the step of conducting the reaction in the presence of a growth enhancer comprising monosulfonated or monosulfated surfactant and a neutralized disulfonated surfactant in a weight ratio of from about 0.14 to 0.69.

Abstract: The invention relates to the treatment of brine and more particularly the treatment of the brine elutriate drawn off after evaporation of the brine at an elevated temperature to separate some of the sodium chloride thereon. The crude brine normally contains sodium sulphate and potassium chloride, sometimes to relatively high levels, and the invention is directed primarily at the separation out of these salts. To achieve this, the brine elutriate is cooled, in chamber (12) whereby an NaCl--/KCl--/Na.sub.2 SO.sub.4 -- salt mixture is separated off by crystallization. The remaining parent solution can be returned to the evaporation stage (10), without disturbing the equalized balance of the secondary salts in the brine to be processed. The NaCl present in the salt mixture can be recovered by deposition with refrigerated water and separation of the Na.sub.2 SO.sub.4.

Abstract: Process for the manufacture of potassium sulphate from solutions containing magnesium chloride and potassium chloride from solutions, more particularly from mother liquors issuing from the treatment of carnallite. According to this process sodium sulphate and potassium chloride are added to the solutions so as to precipitate sodium chloride and schoenite (K.sub.2 SO.sub.4.MgSO.sub.4.6H.sub.2 O) and the schoenite is treated in a known manner to produce potassium sulphate.

Abstract: A process for separating lead includes the steps of dissolving a water insoluble lead salt in an acetate solution and precipitating the lead by treating the acetate solution with a sulfite so as to form an insoluble lead sulfite. The acetate is recovered by concentrating the solution and precipitating the acetate therefrom, drying the acetate crystals and dissolving them in methanol. The methanol is then evaporated leaving purified acetate crystals. The process is shown as part of a precious metal recovery system in the treatment of tankhouse slime.

Abstract: In a treatment of carnallitic ores by treatment with a decomposition-brine containing amounts of MgCl.sub.2, KCl and NaCl suitable for precipitating artificial sylvinite in a solution of MgCl.sub.2 saturated in KCl and NaCl, the improvement of adding to said decomposition-brine a collector, e.g., a fatty amine acetate, for the flotation of KCl and a source of gas, preferably a gas-liberating additive such as H.sub.2 O.sub.2, so as to contact newly formed crystal nucleii of KCl selectively with said collector and to contact bubbles of said gas with said collector so as to form a froth enriched in KCl simultaneously with the decomposition of said carnallite, the process being particularly useful for treatment of underground carnallitic ore whereby the froth and brine are withdrawn at the surface, separated, and the brine, after make-up additions, is recycled to the ore formation.

Abstract: A liquid melt becomes converted to crystalline form at a particular temperature either spontaneously or when artificially nucleated. The liquid releases heat at crystallization. If the liquid is in a supercooled state when it begins to crystallize, its temperature will rise from the particular temperature at which it is nucleated.Another liquid material is mixed with the liquid to be crystallized. The liquid additive has properties of forming a metastable solid together with the crystallizing material. When the liquid additive exsolves, the crystalline aggregate is weakened and is easily decomposed into fragments of small size. The liquid additive materials may include monohydric alcohols, diols and triols. The liquid additive material may be included in the liquid to be crystallized, in small amounts, amounts to two percent (2%) to five percent (5%) being typical.

Abstract: Potassium chloride of at least technical grade is recovered from sylvinite or sylvinite-like starting materials (sylvite) by leaching with hot mother liquor recycled from a crystallizing stage, the residue consisting substantially of sodium chloride is separated and the solution is cooled to crystallize the potassium chloride. In order to avoid losses to potassium chloride and to reduce problems relating to equipment materials in separating water-insoluble impurities the finely ground starting materials are treated at ambient temperatures with a solution which is saturated with sodium chloride and potassium chloride, and water-soluble impurities are entrained with the solution. The solution is then separated from the water-insoluble impurities and is recycled at least in part to produce the pulp.

Abstract: A process for preparing thermally stable ammonium nitrate-containing granules having high bulk density, high impact resistance, high crushing resistance, and little or no tendency to cake by spraying a liquid composition containing at most 15% by weight water, a stabilization agent, ammonium nitrate and other components into a fluidized bed of ammonium nitrate seed particles thereby forming granules and recovering the thus formed ammonium nitrate-containing granulated product.

Abstract: Disclosed is a method of increasing and maintaining high concentrations of potassium chloride in a refinery process stream of brine containing potassium chloride, sodium chloride and a minor amount of salt impurities by mixing with a first process stream potassium chloride crystallized from a pond wherein a brine from a second process stream is concentrated by solar evaporation and/or cooled by low ambient air temperatures.

Abstract: Industrially crystallized potassium chloride having a potassium chloride content of at least 95 weight percent and containing a minor contaminating amount of inorganic metal salt impurities, e.g., sodium chloride, is purified by leaching compacted particles of said potassium chloride with an aqueous leaching solution, the solute of which solution is selected from the group consisting of potassium chloride and mixtures of potassium chloride and sodium chloride. The leaching solution is saturated with respect to potassium chloride and substantially unsaturated with respect to sodium chloride. The compacted particles are maintained in contact with the leaching solution for a time sufficient to reduce substantially the sodium chloride content thereof, and potassium chloride particles of reduced sodium chloride content are recovered from the leaching solution. The leached compacted particles are transparent and comprise single and compound euhedral cubic crystals.

Abstract: This invention relates to a method of producing articles which generate heat at a substantially constant temperature for an extended period of time and which are able to remain in a stable state until such time as the generation of heat is desired. The method also relates to supercooled fluids produced by such methods. The method involves the processing of supercooled fluids such as hypo to produce this stable state. As a first step, a suitable material such as ethylene glycol may be added to the supercooled fluid to stabilize the supercooled fluid and to decrease the generation of heat in the supercooled fluid to obtain a desired temperature. The mixture is then heated to a relatively high temperature considerably above the melting temperature of the supercooled fluid. With the mixture at the high temperature, water is added to provide a particular specific gravity and an alkali is added to provide a particular pH.

Abstract: An improved method of producing potassium sulfate from langbeinite. The improved method employs a "salting out" step to remove additional KCl from the mother liquor resulting from K.sub.2 SO.sub.4 crystallization. NaCl is added to the mother liquor to cause precipitation of KCl crystals. The amount of NaCl added is controlled to an amount below the saturation point for NaCl in the solution to avoid contaminating the KCl with solid NaCl. The KCl crystals are recycled back to the K.sub.2 SO.sub.4 reactors as a source of KCl. The "salting out" step eliminates an energy-intensive submerged combustion evaporation step from the K.sub.2 SO.sub.4 recovery process and consequently reduces atmospheric emissions.