Abstract: Metal cyanide suitable for shipment is prepared by introducing an aqueous metal cyanide feed stream to a crystallizer to form a slurry of metal cyanide crystals in their mother liquor. The crystallization step occurs at a temperature between 30.degree. C. and 70.degree. C., and preferably between 50.degree. C. to about 60.degree. C. The metal cyanide crystals are separated from their mother liquor to form a wet cake product containing from about 75 to 98 wt. % anhydrous metal cyanide crystals, from about 4 to 24 wt. % water, and from about 1 to 5 wt. % of metal hydroxide. The wet cake product is placed into a shipping container for shipment to a desired location. A metal cyanide solution is prepared by dissolving the wet cake product.

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: In a process for preparing crystalline NaOH.3.5H.sub.2 O, NaOH.3.5H.sub.2 O is allowed to crystallize from an aqueous sodium hydroxide solution which contains sodium chloride and is saturated in respect of NaOH.3.5H.sub.2 O and the crystals formed are separated from the solution using a mechanical solid/liquid separation apparatus, wherein the solid/liquid separation is carried out under conditions under which the crystalline NaOH.3.5H.sub.2 O is freed sufficiently of residual solution adhering to the surface for the sodium chloride content of the crystalline NaOH.3.5H.sub.2 O obtained to be less than 100 mg per kg. The crystalline NaOH.3.5H.sub.2 O is subjected to an additional purification step, which may include the at least superficial melting or the at least superficial dissolution of the crystals, in combination with a solid/liquid separation step. The additional purification step. The additional purification step comprises washing the crystalline NaOH.3.5H.sub.2 O separated off.

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: Alkali metal bicarbonate salts, e.g., sodium bicarbonate, are crystallized from aqueous solutions thereof in the presence of a crystal growth promoting amount of lecithin or lecithin containing compositions. Alkali metal bicarbonate salts include sodium bicarbonate, potassium bicarbonate and lithium bicarbonate. The process is described as providing increased amounts of large crystals and a narrower and more uniform crystal size distribution.

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: A method of producing sodium carbonate crystals from a sodium carbonate-containing solution including the steps of passing the sodium carbonate-containing solution to a precipitator, adding methanol to the sodium carbonate-containing solution in the precipitator such that a resultant liquor has methanol in a concentration of between 15% and 70% by volume, precipitating the sodium carbonate crystals from the resultant liquor, washing the precipitated sodium carbonate crystals with an alcohol-containing solution and drying the washed precipitated sodium carbonate crystals. The sodium carbonate-containing solution has a sodium carbonate concentration ranging between 100 g/l to saturation. The methanol is in residence with the sodium carbonate-containing solution for between 10 and 100 minutes. The alcohol-containing solution has an alcohol concentration ranging between 50% and 100%.

Abstract: A process for forming useful sodium salts by uniquely processing dilute mine brines obtained by solution mining of a sodium bicarbonate containing ore deposit with an aqueous solvent is disclosed. The dilute mine brine is reduced in sodium bicarbonate content to prevent precipitation of the sodium bicarbonate in subsequent crystallization of sodium carbonate decahydrate. The reduced mine brine is directed to a crystallizer operated to form pure sodium carbonate decahydrate crystals and a carbonate/bicarbonate containing mother liquor in which the bicarbonate content is less than 4.5% by weight. The mother liquor is then steam stripped to convert a portion of the dissolved sodium bicarbonate in the mother liquor to sodium carbonate to form a carbonate enriched brine. The carbonate enriched brine is then recycled as a portion of said aqueous solvent to be used in the solution mining of the ore deposit.

Abstract: Disclosed are a variety of processes for the purification of saline minerals and in particular, trona. Some of the processes include a combination wet and dry recovery process which results in high recovery and purification at relatively low cost. The dry separation methods can include density separation, magnetic separation and electrostatic separation. Other processes include a modified slush process for the purification of calcined trona (sodium carbonate) by the introduction of anhydrous sodium carbonate into a saturated brine solution and subsequent separation of insoluble impurities.

Abstract: Methods for the production of nickel or ammonium hypophosphite are disclosed, including combining sodium hypophosphite with nickel or ammonium sulfate to produce sodium sulfate and nickel or ammonium hypophosphite, and lowering the temperature of the solution containing the sodium sulfate to crystallize out the sodium sulfate.

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: 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: A process wastewater treatment plant, and a process relating thereto, which converts process wastewater generated in battery manufacturing and the like into clean process water and sodium sulfate salt by treating the process wastewater to remove impurities and contaminants, including debris, oil/grease, heavy metal oxides, lead and other heavy metals, suspended solids, bacteria, organic compounds, and/or gases, from the wastewater to produce a clean neutral sodium sulfate brine, subjecting the brine to heat to obtain distilled water and sodium sulfate salt, and purifying the distilled water by reverse osmosis for reuse as clear process water.

Abstract: A solution mining process for recovering sodium values from an underground deposit of a sodium bicarbonate containing ore is disclosed. The process involves contacting the ore with an aqueous sodium carbonate-containing solution to produce a dilute brine which is stripped with steam to reduce the bicarbonate content and increase the carbonate content. The dilute carbonate/bicarbonate solution from the stripper is fed to a sodium carbonate decahydrate crystallizer to produce pure sodium carbonate decahydrate crystals and a mother liquor containing less than about 4% sodium bicarbonate.

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: The present invention pertains to a crystalline hydrated layered sodium silicate/amorphous sodium silicate composite material with predetermined hardness ion sequestration properties achieved by control of the process for forming the material, and a process for making the material. The process for producing the crystalline hydrated layered sodium silicate/amorphous sodium silicate composite consists of producing a crystalline sodium disilicate by heating a sodium silicate at a specified time and temperature. The resulting material may include amorphous material, and the crystalline sodium disilicate can be either alpha-phase or delta-phase disilicate. This crystalline sodium disilicate is then hydrolyzed with up to 50.0 milliequivalents per gram of either H.sub.3 O.sup.+ ions or OH.sup.- ions. The resulting material can sequester Ca.sup.2+ ions, Mg.sup.2+ ions, or both, depending on the results desired, processing conditions, and starting materials used.

Abstract: The present invention is an improved method for crystallizing inorganic salts. The inorganic salts that are suitable for this process are characterized by the fact that they form isothermic or polythermic concave solubility curves. Each concave solubility curve represents saturated concentrations of the salt that is desired to be purified versus either concentrations of a second, different inorganic salt or versus temperature.

Abstract: The invention is a process for the hydrothermal production of crystalline sodium disilicate by heating an aqueous mixture of quartz sand and sodium hydroxide or an aqueous solution of sodium disilicate with a solids content of at least 50% by weight or more than 75% by weight at a temperature above 235.degree. C. and under autogenous pressure to form crystalline sodium disilicate.

Abstract: The present invention provides a process for recovering alkali carbonates such as alkali sesquicarbonates from slurries of minerals such as Trona which contain those carbonates as well as clays and shales. The invention further provides a method for recovering alkaline earth carbonates from caustic slurries of those carbonates, as well as to clarifying the supernatant liquids which result from recovery of the alkaline earth carbonates.

Abstract: Glycine and sodium sulfate decahydrate are separated from a starting aqueous solution containing glycine, sodium sulfate, and impurities, by forming a slurry which is a solid mixture of glycine and sodium sulfate decahydrate, followed by separation of the mixed 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 process of continuously crystalizing sodium percarbonate by the reaction of sodium carbonate with hydrogen peroxide using first and second reaction vessels includes the steps of: (a) continuously feeding a first feed solution containing sodium carbonate and a second feed solution containing hydrogen peroxide into the first reaction vessel, thereby to form therein a first slurry containing seed crystals of sodium percarbonate; (b) continuously discharging the first slurry from the first reaction vessel into the second reaction vessel while step (a) is performed; (c) continuously feeding at least one of hydrogen peroxide and sodium carbonate into the second reaction vessel while steps (a) and (b) are performed thereby to form therein a second slurry containing final sodium percarbonate crystals grown from the seed crystals; (d) continuously discharging the second slurry from the second reaction vessel while steps (a), (b) and (c) are performed; (e) continuously separating the second slurry into the final sodi

Abstract: A process for preparing microcrystalline perborate hydrate products and highly concentrated, storage stable aqueous solutions used for this purpose which have a stable active oxygen content and a boron content of 3 to 8% by wt. based on the total weight of the solution. The products of the invention are suitable for numerous uses in the field of bleaching agent, disinfectant and liquid detergent formulations, and other fields of use.

Abstract: Process for the manufacture of sodium bicarbonate particles having an ovoid or spherical shape, the process preparing an aqueous solution of sodium bicarbonate, which is supersaturated; circulating the aqueous solution supersaturated in sodium bicarbonate through a bed of crystals in order to cause the bed to be a mobile bed in which the crystals are in continuous motion, and to cause crystallization of the sodium bicarbonate particles and at least partial desupersaturation of the aqueous solution supersaturated in sodium bicarbonate to provide a mother liquor and, withdrawing the sodium bicarbonate particles from the bed.

Abstract: A process for producing valuable sodium-based chemicals from a brine containing sodium carbonate and sodium bicarbonate, such as those containing from about 8% to about 20% total alkali obtained by contacting water with an underground trona formation by heating the brine at about 100.degree. C. to about 140.degree. C. to evaporate water, convert sodium bicarbonate to sodium carbonate and to drive off resulting carbon dioxide, reacting the brine with reduced sodium bicarbonate with an aqueous sodium hydroxide solution in amounts to convert essentially all of the remaining sodium bicarbonate in the brine to sodium carbonate, cooling to about 5.degree. C. to about 25.degree. C. to precipitate sodium carbonate decahydrate crystals, separating the crystals from their mother liquor, melting the separate crystals to form a sodium carbonate solution, heating the solution to from above about 60.degree. C. to below 110.degree. C.

Abstract: A process is described for producing sodium-based chemicals from a brine containing sodium carbonate and sodium bicarbonate by heating the brine to evaporate water and drive off carbon dioxide and obtain a solution that will crystallize sodium sesquicarbonate, cooling the solution, precipitating sodium sesquicarbonate crystals and separating a first mother liquor from the sesquicarbonate crystals. The first mother liquor is then cooled to a lower temperature to precipitate sodium carbonate decahydrate crystals, the decahydrate crystals are separated from a second mother liquor and the decahydrate crystals are recovered for use in the manufacture of sodium-containing chemicals, such as sodium carbonate monohydrate, anhydrous sodium carbonate or soda ash.

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: Process for disposing of insoluble tailings that remain when solubilizing uncalcined or calcined trona in the process of producing soda ash, in which the tailings are slurried with water or waste solutions of sodium carbonate and/or sodium bicarbonate, adding an alkali metal hydroxide or alkaline earth metal hydroxide in effective amounts up to about 10% by weight of the aqueous slurrying solution, pumping the slurry into a well connected to an underground mined-out cavity with sufficient pressure to prevent build-up of tailings from plugging the bottom of the well opening, dispersing and settling said tailings in the cavity, removing a liquor from said cavity whose concentration of sodium carbonate and/or sodium bicarbonate has been increased and recovering such enriched liquor for use in the manufacture of sodium-containing chemicals such as soda ash.

Abstract: In a purification process for brine, impurities such as calcium, magnesium and/or sulphate are precipitated by the addition of calcium hydroxide (Ca(OH).sub.2) and sodium carbonate (Na.sub.2 CO.sub.3). Following NaCl crystallization by evaporation of the brine, a mother liquor is obtained which still contains among others sulphate, potassium and bromide ions. Further concentration of this mother liquor by evaporation results in the precipitation of both NaCl and Na.sub.2 SO.sub.4 and a more strongly concentrated mother liquor with respect to both potassium and bromide remains. This concentrated mother liquor is drained off. Either the precipitated NaCl and Na.sub.2 SO.sub.4 are dissolved in water or the Na.sub.2 SO.sub.4 is dissolved in purified brine or crude brine and then returned to the brine purification process, thereby lowering both the potassium and bromide ion levels in the purified brine. As a consequence the contents of both potassium and bromide of the NaCl are reduced.

Abstract: A method for improving abrasion resistance of sodium perborate tetrahydrate crystals prepared by reacting sodium metaborate with hydrogen peroxide in an aqueous slurry crystal growth medium, the improvement including highly supersaturating the aqueous slurry crystal growth medium. Also, an agent such as an excess of caustic may be added to the aqueous crystal growth medium to limit the growth rate of individual crystals.

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: The invention discloses a method in the electrolytic production of alkali metal chlorate which is recovered by crystallization and separation of the crystals from a solution recycled to the electrolysis process. A given proportion of the crystals formed are separated and removed from the mother liquor after they have been in contact with the mother liquor for a shorter period of time than the remaining crystals, whereby they obtain a sulphate content which is higher than in the crystals that have been in contact with the mother liquor for a longer period of time.

Abstract: Process for removing an industrial residue containing sodium sulphate, in which the sodium sulphate in the residue 7 is treated with a calcium salt 12 to precipitate calcium sulphate 13, which is sent to a rock salt deposit 15, from which an aqueous solution of sodium chloride 16 is withdrawn.The process applies to the residues from the desulphurization of fumes by means of sodium bicarbonate.

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: Disclosed is a method of removing sulfate ion from an aqueous sodium chlorate liquor. A crystallization temperature is selected between about -15.degree. and about 0.degree. C. and the maximum concentration of sodium chlorate that is soluble in the liquor at that temperature is determined. The liquor is diluted so that the concentration of sodium chlorate in the liquor is less than that miximum concentration and the liquor is cooled to that temperature so that the sulfate ion in the liquor crystallizes as sodium sulfate decahydrate but the sodium chlorate does not crystallize.

Abstract: Process for removing sodium sulphate from an aqueous citrate, adipate or phosphate buffer solution used for absorption of SO.sub.2 from exhaust gases, by evaporating an aqueous buffer solution at atmospheric pressure at a temperature near its boiling point, thereafter separating the precipitated sodium sulphate and optionally subjecting it to further treatment to recover accompanying buffer salt. The further treatment may consist in a treatment of the precipitated sodium sulphate together with accompanying buffer salt with water at elevated temperature. The solution which is then obtained is mixed with the rest of the buffer solution.

Abstract: Disclosed is a process for preparing crystals of anhydrous sodium sulfide, the process being characterized in that the process comprises the steps of heating a water-containing non-crystalline sodium sulfide at a temperature of about 30.degree. to about 89.degree. C. under a pressure of about 500 torr or less for about 2 hours or longer in a first-stage heating step and further heating the sodium sulfide at a temperature of about 90.degree. to about 200.degree. C. under atmospheric pressure or reduced pressure for about 2 hours or longer in a second-stage heating step.

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: Process for disposing of insoluble tailings that remain when solubilizing uncalcined or calcined trona in the process of producing soda ash, in which the tailings are slurried with water or waste solutions of sodium carbonate and/or sodium bicarbonate, pumping the slurry into a well connected to an underground mined-out cavity with sufficient pressure to prevent build-up of tailings from plugging the bottom of the well opening, dispersing and settling said tailings in the cavity, removing a liquor from said cavity whose concentration of sodium carbonate and/or sodium bicarbonate has been increased and recovering such enriched liquor for use in the manufacture of sodium-containing chemicals such as soda ash.

Abstract: An aqueous ultra-dilute composite solution, which comprises 1.4.times.10.sup.-7 to 2.7.times.10.sup.3 ppm of a chlorine ion, and 4.times.10.sup.-12 to 4.times.10.sup.-3 ppm of a sodium ion or 7.times.10.sup.-8 to 1.3.times.10.sup.3 ppm of an iron ion, and is capable of forming sodium chloride having an oblate tetrahedral crystal form.

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 crystallization, and brine recirculation techniques in the systems for electrolyzing brine.

Abstract: Disclosed are single crystals of anhydrous sodium sulfide, and a method of producing single crystals of anhydrous sodium sulfide, characterized in that the method comprises concentrating an aqueous solution of sodium sulfide at a temperature of 97.degree. C. or higher, the solution containing about 2 to about 15% by weight of NaOH based on the aqueous solution to precipitate single crystals of anhydrous sodium sulfide from the aqueous solution.

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: Soda values are recovered from waste water and impurities are rejected to bitterns ponds by a low temperature crystallization process. In the process, waste water, typically containing 7-14% equivalent soda ash, is reacted with lime to neutralize bicarbonate. The liquor is subsequently clarified and fed into a multiple effect evaporator cooling circuit where it, along with the recirculating cooling water, is heated. The heated clarified liquid is then fed to an evaporative cooling system. Water is evaporated in the cooling tower and the liquor is cooled. The effluent liquor from this system now contains 17-24% soda ash. Most of this stream is recycled back to the multiple effect evaporator's cooling circuit for reheating. Approximately 10% of this stream is fed forward to an air cooled cooler-crystallizer where sodium carbonate decahydrate is crystallized. The decahydrate crystallized is relatively pure, while the sulfate is concentrated in the mother liquor.

Abstract: An improved process for the manufacture of soda ash from trona by the sodium carbonate monohydrate method utilizing an activated carbon treatment of evaporator fines bleed.

Abstract: A process for the preparation of a crystalline sheet-type alkali metal silicate is described, in which an aqueous solution of an alkali metal silicate or a suspension of an amorphous alkali metal silica having a molar ratio M.sub.2 O (unneutralized)/SiO.sub.2, where M represents an alkali metal, of 0.05:1 to 0.8:1 is allowed to react at temperatures of 70.degree. to 250.degree. C. until the sheet-type alkali metal silicate crystallizes out. After the beginning of crystallization, an acidic compound is added in an amount such that an M.sub.2 O (unneutralized)/SiO.sub.2 ratio of 0.05:1 to 0.8:1 is constantly maintained in the mother liquor of a filtered sample. However, at least an amount corresponding to 5 milliequivalents of H.sup.+ per mole of SiO.sub.2 in the alkali metal silicate used is added. The use of seed crystals of the desired sheet silicate is advantageous.

Abstract: Crystal solids made via the continuous crystallization of a crude, concentrated aqueous feed solution are recovered as a crystalline solid product that is relatively free of impurities present in the crystallizer liquor. A portion of the withdrawn crystallizer slurry is concentrated in a first hydroclone, diluted with crystallizer feed solution, concentrated in a second hydroclone, and centrifuged and dried to recover the crystalline solid product.