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: A method is described for producing silicon carbide particles using solar energy. The method is efficient and avoids the need for use of electrical energy to heat the reactants. Finely divided silica and carbon are admixed and placed in a solar-heated reaction chamber for a time sufficient to cause a reaction between the ingredients to form silicon carbide of very small particle size. No grinding of silicon carbide is required to obtain small particles. The method may be carried out as a batch process or as a continuous process.

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 method for the manufacture of large area silicon crystal bodies suitable for use in the manufacture of solar cells wherein silicon powder having a small grain size is used as the starting material. This powder is compressed to form a thin layer in a suitable form, the form having at least a surface composed of silicon or a silicon compound. The form is filled to a depth approximating the final dimensions of the article. The powder is sintered in the form, and the compressed, sintered layer is converted into a self-supporting silicon foil. This foil is melted partially up to at least half its thickness and recrystallized in a two-stage temperature treatment. The melting occurs by means of a single-sided energy irradiation. The silicon foil is not deteriorated in terms of its mechanical stability and shaped by means of the single-sided, optical type heating.

Abstract: An improved harvester for harvesting a salt crop from the bottom of a shallow, elongated solar crystallizer containing a substantially saturated salt solution overlying the salt crop. The harvester includes track means extending longitudinally along the sides of the crystallizer on which a pair of carriages are movably mounted and support the ends of a frame extending transversely across the crystallizer. The frame includes salt gathering means for transferring the salt crop laterally in the form of one or a plurality of longitudinally extending furrows or ridges in response to the travel of the harvester along the tracks and the resultant gathered salt is extracted by one or a plurality of suction inlets disposed in alignment with the furrows in the form of an aqueous brine slurry. The extracted salt crop is subsequently separated and recovered while the liquid brine is returned to the crystallizer.

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: 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: Partially purified salt containing less than about 00.4 weight percent insolubles is further purified to reduce the insolubles until the milk pad rating is 3 or better for certain industrial uses and 1 for human consumption. The entry salt is washed in clarified brine to dislodge insoluble impurities adhered to the salt surfaces. The washed salt is then scrubbed with fresh water sprays to displace the wash brine from salt surfaces. The washed salt is drained and then dried in a kiln where flowing air blows away some impurities. The dried salt is passed through a magnetic separator, doubly sifted to remove both large and small impurities, and, where food grade salt is required, passed through a color sorter that removes relatively dark impurities.

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: A method of changing the salt content of a solution is described by including the salt in a nonconvective solar pond heated by solar radiation and having stable salt-concentration and temperature gradients increasing from the top to the bottom of the pond, the bottom layer of the pond being a substantially saturated solution at a predetermined temperature. A feed solution containing the salt is introduced directly into the bottom layer and is circulated through the bottom layer. The predetermined temperature of the bottom layer is different from the initial temperature of the feed solution when introduced into the pond bottom layer and is selected to effect a change in solubility, and thereby a change in the salt content, of the feed solution by causing salt in the feed solution to be precipitated therefrom, or additional salt to be dissolved therein.

Abstract: The improved production of sodium sulfate, potassium sulfate and other valuable salts from salt plant bitterns or the like wherein initial reduction in sulfate ion concentration yields salt cake and greatly facilitates the selective recovery of potassium and other valuable by-product salts. The process includes cooling the bitterns while below a certain concentration to produce glauber salt, followed by successive solar evaporation steps to yield harvestable potash salts. The salts are selectively treated and then refined by flotation. The flotation overflow is converted to potassium sulfate product by decomposition and crystallization steps and the underflow provides a recycle salt mixture for converting the glauber salt to salt cake.

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: By evaporation employing solar energy, a brine having a lithium chloride concentration greater than that of a brine whose vapor pressure under ambient conditions is substantially equal to the partial pressure of moisture in the atmosphere above the brine is obtained. The process by which such result is accomplished involves the use of a pond system consisting of a series of shallow ponds of relatively large surface area to which a dilute lithium chloride brine is introduced. The flow of the brine through the pond system is controlled so that, at a point intermediate the points of introduction of the brine to and withdrawal of the brine from the pond system, the concentration of the brine is such that its vapor pressure under ambient conditions is substantially equal to the partial pressure of the moisture in the atmosphere immediately above the pond system.

Abstract: Disclosed is a process for the production of partially dehydrated or anhydrous salts from higher hydrates of the same salt, utilizing solar energy. Hydrated salts which have an increasing solubility with an increase of temperature, possessing a transition temperature from the existing high hydrated form to the desired one in the range of between about 30.degree. C. to about 100.degree. C. are partially or completely dehydrated in a solar pond having a non-convecting characteristic. Examples of salts produced according to the present invention are: anhydrous sodium sulfate from sodium sulfate decahydrate, magnesium sulfate monohydrate from magnesium sulfate heptahydrate, sodium carbonate monohydrate from sodium carbonate decahydrate and sodium borate pentahydrate from sodium borate decahydrate.

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: A subterranean salt deposit is solution mined, and the resulting calcium- and sulfate-contaminated brine is treated, e.g., by soda ash, to precipitate insoluble calcium compounds. The resulting slurry is settled, and the effluent clear brine is evaporated in a series of solar ponds to produce high-grade sodium chloride.The brine becomes progressively more concentrated with respect to sodium sulfate as it moves through the solar ponds. The sulfate-enriched brine may be recycled to the solution mine, evaporated to form a sulfate-contaminated sodium chloride crystal crop, or it may be subjected to winter cooling to remove sulfate values as Glauber's salt, the residual brine being recycled to the solar ponds or the solution mine.

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.