Abstract: Process of crystal growth by diffusion, particularly intended to be carried out on board a space vessel and according to which a substance (5) to be crystallized, contained in a crucible (4), is brought into presence with a precipitating agent (9) through a diffusion wall (6) obturating said crucible. According to the invention:in a first recipient (1) is arranged said crucible (4) containing the substance to be crystallized and obturated by said wall;said first recipient (1) is obturated by a stopper (3) of porous material;in a second recipient (12) is arranged a porous body (19);said first and second recipients are brought together so that said porous body and said stopper of porous material are in contact with each other; andsaid precipitating agent is injected into said porous body (19) of said second recipient (12) through (15).

Abstract: A method for preparing substrates for VLS fiber producing reactions and a method for preparing SiC fibers by the VLS process. The first method includes the steps of forming an alcohol sol containing a fiber growth promoter material precursor, applying the sol to at least one surface of the substrate and drying the sol. More particularly, the steps can include forming a sol of colloidal hydrous metal oxide particles in a liquid, the metal oxide being a fiber growth promoter material precursor and the liquid being capable of dissolving a salt of the metal and of wetting the substrate surface as a sol, applying the sol to at least one surface of the substrate and drying the sol.

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: This invention relates to a copper etching process which involves contacting the copper with an aqueous etching solution comprising sulfuric acid and a peroxide to which is added less than about 0.2% of an organic additive useful as a crystallization control agent and selected from the group consisting of a low molecular weight glycol and gum arabic. With this compound present, copper sulfate crystals do not adhere to the tank and removal of the crystals from the bath is facilitated.

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: 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: A process is disclosed for producing a relatively pure solid ammonium metatungstate by precipitating the solid from a mixture of an ammonium metatungstate solution and a lower alcohol having the formula C.sub.n H.sub.n+1 OH. The ammonium metatungstate solution which is used can be made by any means including the adjusting the pH of an ammonium paratungstate solution followed by digestion of the solution to form ammonium metatungstate.

Abstract: Boric acid is crystallized from saturated aqueous solutions thereof by adding to the solutions small proportions of water soluble polymers which control the particle size distribution of the boric acid during crystallization.

Abstract: A solar crystallizer and a process for producing solar salt adaptable for use in climates heretofore believed unfavorable for solar salt production. The invention employs a solar crystallizer defining a shallow pond of salt solution the level of which is carefully monitored and controlled by withdrawing unsaturated solution from the upper stratum of the pond such as produced from rainfall and introducing substantially saturated brine into the pond at a lower stratum overlying the salt crop on the bottom thereof providing a continuous protective saturated brine layer and enhancing the efficiency of water evaporation by a comparatively shallow depth.

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: A low boiling, water soluble organic solvent is added to a saturated brine to thereby reduce the salt solubility of the brine and cause precipitation of the salt. The precipitated salt is filtered out and dried. The remaining brine-solvent mixture is distilled to remove the solvent which is reused. Unsaturated brine that is generally free of solvent is returned for resaturation with salt.

Abstract: In a gradient process of growing crystals from liquid media, the need for mechanical seed holders is eliminated in that a solvent is used which at the instantaneous temperature and under the instantaneous pressure employed in the growing process has a density which is equal or approximately equal to the density of the crystal or crystals which is or are being grown.

Abstract: A method for continuously controlling the formation of crystal fines in a continuous crystallizing process in which product crystals are produced in a crystallizing zone from crystallizable material in a mother liquor, and in which product crystals are thereafter recovered. The invention is practiced by adding a flocculant, specific to the crystallizable material, to the mother liquor at a rate effective to cause flocculation of particles of crystallizable material in the mother liquor. One embodiment of the invention is practiced in a process for producing sodium bicarbonate crystals by adding anionic polyacrylate and/or polyacrylamide polymers to a sodium carbonate-containing feed brine received in a carbonator.

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: A waste-water concentrate containing boric acid together with chemical residues and radionuclides, especially from a nuclear power plant, is treated to recovering boric acid which can be recycled to the plant. According to the invention, the practically neutral solution is acidified with an acid selected from the group which consists of sulfuric acid, hydrochloric acid, nitric acid and acetic acid to precipitate the boric acid which is separated from the concentrate and subjected to at least one recrystallization step. The boric acid thus obtained is of comparatively high purity.

Abstract: A reversible liquid/solid phase change composition comprising hydrated Mg(NO.sub.3).sub.2 /MgCl.sub.2, and one or more of Sr(OH).sub.2, Ca(OH).sub.2, CaO or BaO, added to the composition in an effective amount to suppress supercooling of the Mg(NO.sub.3).sub.2 /MgCl.sub.2 liquid phase.

Abstract: Process for preparation of monodispersed crystalline particles from amorphous crystallizable polymers. In this process, an amorphous polymer of an inorganic glass, such as selenium, or of organic polymer, such as a polyester, is initially contacted with a crystal inducing fluid under certain specified conditions. Concurrent with such contact the crystallizable polymer is subjected to physical and/or ultrasonic forces. This combination of steps results in the substantially complete conversion of the amorphous polymer to monodispersed crystalline particles. In the case of crystallization of amorphous selenium, this process is directive for preparation of the corresponding triclinic crystalline form of this material.

Abstract: Degradation of heat storage capacity in Glauber's salt heat storage compositions on thermal cycling is substantially decreased by addition of small amounts of crystal habit modifiers.

Abstract: A reversible liquid/solid phase change composition comprising hydrated MgCl.sub.2 and one or more of Ba(OH).sub.2, Sr(OH).sub.2, CaO, SrCO.sub.3, BaO, Ca(OH).sub.2, Mg(OH).sub.2, MgO, Na.sub.3 AlF.sub.6 or CaC.sub.2 O.sub.4, added to the composition in an effective amount to suppress supercooling of the MgCl.sub.2 liquid phase.

Abstract: A method of manufacturing table salt effectively containing an efficient amount of the minerals from the sea water by using not fuel or electric energy but natural energy only. The method comprising the steps of infiltrating and flowing down the sea water from a hollow tower made of liquid permeable materials and producing primary salt water adding raw salt thereto to cause low solubility components to be separated and precipitated leaving residual salt water, and evaporating the moisture from said residual salt water at ambient temperature and humidity to produce table salt.

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.

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: A reversible liquid/solid phase change composition comprising hydrated Mg(NO.sub.3).sub.2 /MgCl.sub.2, and one or more of Sr(OH).sub.2, Ca(OH).sub.2, CaO or BaO, added to the composition in an effective amount to suppress supercooling of the Mg(NO.sub.3).sub.2 /MgCl.sub.2 liquid phase.

Abstract: A crystalline SiO.sub.2 --modification, which is characterized by an X-ray diffraction diagram having certain diffraction lines, and a process for the preparation of this crystalline SiO.sub.2 --modification by crystallizing reactive amorphous SiO.sub.2 under hydrothermal conditions in the presence of hexamethylenediamine. Sodium ions, phosphate ions and/or sulfate ions may be added for the crystallization.

Abstract: The invention contemplates a process for the crystalline precipitation of a chromogen from solution thereof in a solvent and within a capillary. The process involves first initiating a course of crystalline precipitation of the chromogen by initially and locally supersaturating the solution within the capillary, and thereafter evaporating the solvent at a rate and in an environment sufficient for further crystallization to proceed unimpeded by local supersaturation.

Abstract: A process for the working up of ammonium sulphate-containing effluent which is contaminated with organic compounds and optionally also ammonium nitrate, comprising evaporating the effluent to produce water vapor which is removed, a concentrated liquid and a crystal suspension, thickening the suspension to obtain solid ammonium sulphate which is removed and liquid which is recycled to an earlier stage, subjecting the concentrated liquid from evaporation to an optional vacuum cooling crystallization to obtain water vapor which is removed and a crystal suspension from which a concentrated liquid is separated off, advancing the concentrated liquid from the evaporation stage or from the vacuum cooling crystallization stage to a crystallizer, introducing ammonia into the crystallizer to decrease the solubility of the ammonium sulphate, thickening the ammoniacal crystal suspension to obtain ammonium sulphate solids which are removed and ammoniacal mother liquor which is advanced to a distillation step for recovery o

Abstract: A salting-out process for recovering lithium from brines which have been concentrated by solar or thermal evaporation. Soluble sulfate salts are added to the strong brine solutions containing lithium to yield lithium sulfate monohydrate. Subsequent treatment of some residual brines with a strong acid will crystallize quantities of boron present as boric acid. Depending on the time of year and type of brine being used, a brine solar heating or plant evaporation system is provided to enhance the recovery processes.

Abstract: The average size of Glauber's salt crystals formed by crystallization of Na.sub.2 SO.sub.4 from aqueous solution in systems comprising Na.sub.2 SO.sub.4, H.sub.2 O and Glauber's salt is decreased by including a fluorine-containing surfactant in the system.

Abstract: An improved process for the manufacture of ammonium nitrate prills and granules in which a water soluble aluminium salt is added to the process stream prior to the concentrate, which is then used in the prilling or granulating process, being formed.

Abstract: Fine crystals characterized by improved morphological homogeneity and a narrow size distribution are prepared by introducing a solution of a crystallizable solute in a solvent into a bed of small inert continuously moving solid particles and initiating crystallization within the solution while it is in contact with the moving particles. The process finds application in the manufacture of diverse crystalline products such as, for example, in the formation of metal oxalates, phosphorescent compounds, and silver halide crystals, as well as in the purification of both organic and inorganic materials.

Abstract: In the manufacture of iron oxide flakes by the steps of mixing an aqueous ferric salt solution with an aqueous alkali solution for thereby inducing an amorphous precipitate and subjecting the precipitate to a hydrothermal treatment, iron oxide flakes of an increased flake size are obtained by adding boric acid or a salt thereof to the mixture prior to the step of hydrothermal treatment.

Abstract: Crystalline sulfur particles of predetermined, controlled, relative attrition resistance having diameters less than about 0.5 inch are formed by shock-crystallizing fused sulfur in an agitated quench medium by controlling the fused sulfur temperature at a predetermined level about 238.degree. F. and below 340.degree. F. correlated with the relative particle hardness desired, and controlling the sulfur-quench temperature gradient at a level of at least about 100.degree. F. Crystalline particles having higher relative attrition resistance are obtained at higher fused sulfur temperatures and higher quenching temperature gradients.

Abstract: Single crystalline, acicular ferric oxide particles are produced by maintaining an aqueous suspension of ferric hydroxide at an elevated temperature at an alkaline pH in the presence of an organic phosphonic acid compound or a hydroxycarboxylic acid compound as a growth-regulating agent.

Abstract: Enhanced recovery of ammonium perchlorate from waste solid rocket propellant is effected by leaching shredded particles of the propellant with an aqueous leach solution containing a low concentration of surface active agent while stirring the suspension.

Abstract: Anhydrous sodium carbonate is crystallized from saturated aqueous sodium carbonate solutions at temperatures in the range of 104.degree. to below 109.degree. C. by adding to the solution very small proportions of additives which function to reduce the transition temperature of monohydrate to anhydrous sodium carbonate.

Abstract: A process for promoting the spherical crystallization of picloram, wherein an anionic polymeric acrylamide flocculating agent, when combined with a solution of picloram in an aqueous sulfuric acid medium, serves to promote the formation of polycrystalline picloram spheres and to greatly reduce the formation of fines.

Abstract: In crystallization of a carbonate of sodium from aqueous solutions, a water soluble homopolymer of oxyethylene or block copolymer of oxyethylene and oxypropylene is employed as a defoamer. The presence of the defoamer in the resulting sodium carbonate does not adversely interfere with carbon dioxide absorption in subsequent production of sodium bicarbonate.

Abstract: A method of separating sulfuric acid from spent chlorine dioxide generator liquor. The method comprises simultaneously adding to the spent liquor, a water-soluble organic compound selected from the group consisting of alcohols and ketones, and water. The resulting solid is separated to leave an aqueous solution of sulfuric acid. The method is of particular application in acid and salt cake recovery from the effluent of a chlorine dioxide generator operating at an acid normality of between 6 and 11.

Abstract: Alpha type calcium sulfate hemihydrate gypsum is obtained by suspending gypsum in an aqueous solution containing a specific monocarboxylate in a specific concentration and heating the resultant suspension in a specific temperature range under atmospheric pressure. The production of this alpha type calcium sulfate hemihydrate is accomplished at an increased rate by adding a specific monocarboxylic acid to the aqueous solution, suspending gypsum in the resultant solution and heating the resultant suspension in a specific temperature range under atmospheric pressure.

Abstract: A process is provided for the recovery of chemicals, such as chlorides, sulfates, carbonates and borates of such alkali metals as sodium and potassium, among others, from underground brines associated with an ore body containing said chemicals, wherein the underground brine is pumped to the surface and confined over said ore body where it is concentrated by solar evaporation and the concentrated brine returned to an underground basin adjacent said ore body and stored for later removal by pumping for the subsequent recovery of chemicals therefrom. Thus, solar evaporation is used to produce the desired concentration of brine to optimize the subsequent recovery of chemicals therefrom, thereby resulting in substantial savings in overall energy costs.

Abstract: Tributoxyethylphosphate is useful in controlling foam produced during the evaporative crystallization of calcined trona solutions. The chemical is effective at low concentrations, i.e. 1 to 30 ppm, and does not significantly alter the crystal habit of the sodium carbonate crystals.

Abstract: Suspension fertilizers containing humic acid as a crystallization inhibitor and crystal growth modifier. Suspension fertilizers containing from 0.05% to 3% humic acid and from 0.25%-3% bentonite have excellent stability as evidenced by a low concentration of crystals, a low crystal growth rate, good suspension characteristics and good rheological properties. An improved method of manufacturing suspension fertilizers which consists of adding from 0.05% to 3% by weight humic acid to the suspension fertilizer, and a method of inhibiting the formation and growth of crystals from a supersaturated solution of at least one fertilizer chemical which comprises adding from 0.05% to 3% by weight humic acid to the solution before it becomes supersaturated.

Abstract: Precursors for the preparation of phosphate glasses are provided. Controlled preparation of the precursors in precise stoichiometric proportions enable the preparation of glasses which are stable and possess superior optical properties of an order similar to optical glasses. Suitable precursors within the contemplation of the invention are those having the formula:M(H.sub.2 PO.sub.4).sub.nwherein M is a metal ion selected from the group consisting of Al, Zn, Cd, Fe, Sn, Mn, Pb, Ni, Co, Ga, and In and the alkaline earth metals Be, Mg, Ca, Sr and Ba and wherein n has a value of 2 or 3 depending on whether M is a divalent or trivalent ion. Mixtures of these compounds may be employed, the admixture being made prior to melting stoichiometric equivalent precursor mixture. In addition, any combination of precursors containing divalent and/or trivalent cations may be selected.

Abstract: A process for preparing from aqueous NaCl brine containing appreciable quantities of dissolved calcium sulfate high purity dendritic salt, characterized by an exceptionally low calcium sulfate content. The process is carried out by a "feed and bleed" procedure comprising admixing an alkali metal polyphosphate with said brine to increase the supersaturation of calcium sulfate therein, feeding the brine containing this additive into an evaporating and crystallizing chamber, evaporating the brine at an elevated temperature and reduced pressure to cause crystallization of pure salt and concomitantly bleeding brine from the chamber, the rate of feed of the brine to the chamber and the rate of bleed of brine from the chamber being such as to maintain the calcium sulfate in the dissolved state and prevent its precipitation with the salt.

Abstract: A method of producing citrine crystals comprising the step of growing citrine crystals under hydrothermal conditions by the temperature difference method in a high-pressure autoclave on crystalline quartz seeding plates oriented in parallel with the pinacoid crystallographic plane {0001} or with planes inclined at an angle within the range of up to 20.degree. with respect to said pinacoid plane using a charge comprising crystalline quartz and aqueous solutions of potassium carbonate with a concentration of from 5-10 wt.%. Said solutions contain iron introduced in the autoclave in the form of metallic iron in an amount of from 2-20 g per lit. of the solution, as well as nitrites or nitrates of alkali metals or potassium permanganate which are introduced in the autoclave in an amount of from 1-20 g per lit. of the solution. The above-described method of growing citrine crystals is carried out at a crystallization temperature of from 300.degree.-345.degree. C, under a pressure of from 300-1500 kg/cm.sup.

Abstract: A process for producing amethyst crystals involving growing of colorless quartz crystals by a hydrothermal method of a temperature drop in a high-pressure autoclave on crystalline quartz seed plates oriented parallel to the crystallographic planes of the major {1011} and minor {1101} rhombohedrons using crystalline quartz as a charge. Said growing is effected from aqueous solutions of potassium carbonate or potassium hydroxide having a concentration ranging from 4 to 7 wt.% and containing iron introduced into the autoclave in the form of metallic iron or in the form of its oxydic or hydroxydic compounds in an amount ranging from 5 to 30 g/l of the solution. The growing process is effected at a crystallization temperature within the range of from 300.degree. to 500.degree. C. under a pressure ranging from 200 to 1,700 kg/cm.sup.2 and a crystal growth rate of from 0.05 to 0.5 mm/day.

Abstract: Process for producing high bulk density sodium carbonate monohydrate crystals from sodium carbonate solutions wherein the sodium carbonate monohydrate is crystallized in the presence of at least 30 parts per million soluble aluminum ions.

Abstract: A process for recovering ammonium sulphate from an aqueous ammonium sulphate solution containing organic contaminants is disclosed. The aqueous solution is contacted with an organic substance which is water soluble and which is capable, in combination with a saturated ammonium sulphate solution, of forming a two-layer system. The organic substance is selected from the group consisting of lactames of 4 to 20 carbon atoms, and mixtures thereof. The resultant two layers may be separated into an aqueous phase containing the ammonium sulphate, and an organic phase containing the organic substance and the organic contaminants. Typical organic contaminants include acrylonitrile prepared from propylene, methyl methacrylate prepared from acetone cyandihydrin, and methyl methacrylate prepared from acrylonitrile. The ammonium sulphate is readily crystallized from the aqueous phase.

Abstract: A process is disclosed for separating cuprous chloride from a solution comprising cuprous chloride and one or more of a number of metal impurities, the process comprising crystallizing the cuprous chloride from the solution in the presence of copper as cupric chloride in a concentration of at least about 20 grams per liter.

Abstract: Abrasion resistant sodium perborate monohydrate is prepared by treating sodium perborate monohydrate with at least 5% of water at a temperature of 20.degree. - 90.degree. C. in a moistening unit and then drying at a temperature beginning at 40.degree. C. and increasing to a maximum of 90.degree. C.