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: Mined salt mixtures comprising sodium-carbonate, -bicarbonate, -chloride, -sulfate, and -double salts, such as trona and burkeite, are leached with a bicarbonate-saturated solution and added carbon dioxide to selectively dissolve the sodium chloride, sodium sulfate and burkeite and to precipitate additional trona, leaving a leach residue consisting essentially of trona. The trona is calcined and dissolved, and the carbonate solution is purified, crystallized and dehydrated in a non-convective solar pond yielding high purity sodium carbonate monohydrate which is converted into dense soda ash. The brine solution from the leach may be treated for the recovery of a further amount of trona.

Abstract: Germanium is recovered from aqueous solutions containing germanium, zinc, and antimony by sorption with an ion exchange resin which has as its matrix a backbone polymer to which are attached amine active groups chosen from secondary and tertiary amines and quaternary ammonium groups. The resin exhibits a high selectivity ratio of germanium relative to antimony. The method is particularly useful for the recovery of germanium from materials or electrolytes encountered in the recovery of zinc from ores and complex concentrates.

Abstract: A process is described for the removal of chloride impurity from zinc sulphate solution. The process comprises the steps of forming a slurry of said solution with an inert particulate support material having elemental silver dispersed thereon, and an oxidizing agent, agitating said slurry at a temperature between about 60.degree. and about 100.degree. C. for precipitation of silver chloride on said support material, filtering said slurry to separate purified zinc sulphate solution from the support material containing the precipitated silver chloride, and treating said separated support material containing precipitated silver chloride with a reductant in an aqueous alkaline medium to regenerate elemental silver on said support material.

Abstract: A process for thermal activation of chalcopyrite-pyrite ore concentrates for activation of iron values in both chalcopyrite and pyrite constituents whereby said iron values can be selectively removed in a subsequent acid leach. Controlled oxidizing conditions are maintained in an oxidizing heating zone for removal of up to about 90% of total sulfur to be removed for conversion of pyrite and chalcopyrite to their acid-leachable forms, measured by a preferable oxidation of 10 to 15% of iron in the concentrate to ferromagnetic oxides, whereby remaining total sulfur to be removed is removed in a reducing zone with the assistance of a low H.sub.2 S/(H.sub.2 +H.sub.2 S) ratio by scavenging of H.sub.2 S by said oxides.

Abstract: A process for precipitation of iron as a jarosite compound from sulfate solution in which said solution fed sequentially through a plurality of reaction zones for oxidation and hydrolysis of ferrous sulfate in the presence of alkali-metal or ammonium ions for jarosite precipitation and simultaneous generation of sulfuric acid is subjected to a "reverse temperature profile", i.e., higher temperature in the last reaction zone than in the first reaction zone, by injection of steam to the last reaction zone.

Abstract: The process of the invention is for the separate recovery of elemental sulfur and residual sulfides and metal salt solution from reaction slurries obtained from leaching of metal sulfides in ores and concentrates.

Abstract: A process for treating thermally activated metal sulfides containing copper, iron and zinc for separate recovery of zinc as zinc sulfide in which the metal sulfides are subjected to a two-stage countercurrent acid leach for the formation of copper sulfide containing acid leach residue and ferrous sulfate solution. The second-stage acid leach is performed in two steps; the first step is operated at a relatively high pulp density and high acid concentration for iron and zinc extraction, the resulting slurry diluted, and the second step is operated at a relatively low pulp density and low acid concentration for dissolution of precipitated ferrous sulfate and precipitation of any dissolved copper values by H.sub.2 S. The diluent solution for the slurry from the second-stage first step preferably is generated sulfuric acid solution from a jarosite precipitation and iron and zinc-containing solution from a subsequent activation leach.

Abstract: A process for the selective extraction of copper chlorides from aqueous solutions by forming a solid addition compound of cuprous chloride with an unsaturated aliphatic hydrocarbon having from 2 to 6 carbon atoms, separating and decomposing the addition compound and recovering solid cuprous chloride. The process can also be used for the separation of copper chlorides from silver-chloride. The process may be applied to the recovery of copper from hydrometallurgical process solutions.

Abstract: A hydrometallurgical process for the separate recovery of non-ferrous, ferrous, and precious metal values and sulfur from metal sulfide ore concentrates by leaching of metal sulfides with a lixiviant containing ferric chloride, cupric chloride and chlorine, precipitating cuprous chloride from the leach solution with butadiene, separating and decomposing the formed addition compound to recover the cuprous chloride, oxidizing and hydrolyzing the cuprous chloride to precipitate cupric oxychloride, converting the cupric oxychloride to cupric oxide, and reducing the cupric oxide with hydrogen for the recovery of copper. The leach residue is treated for the recovery of elemental sulfur and gold. Brine solution resulting from the conversion of cupric oxychloride to cupric oxide is electrolyzed for the production of sodium hydroxide for the cupric oxychloride conversion, hydrogen for the cupric oxide reduction and chlorine, which is partly used in the recovery of gold and partly recycled to the concentrate leach.

Abstract: A process for the treatment of complex lead sulfide-containing concentrates additionally containing at least one metal of the group consisting of iron, copper, zinc, silver, arsenic, antimony, bismuth and gold which comprises the steps of selectively leaching a concentrate with iron-containing lixiviant for converting lead sulfide in said concentrate to lead chloride and forming a leach residue and a leach solution, subjecting said lead chloride in the leach residue to a two-stage, countercurrent, hot brine leach to dissolve the lead chloride in a brine-leach solution, subjecting the brine leach solution to crystallization by evaporative cooling for the separate recovery of crystallized lead chloride, residual brine and crystallization condensate, and returning said residual brine to said brine leach, subjecting crystallized lead chloride in admixture with sodium chloride to electrolysis in a fused bath for production of lead and evolution of chlorine, absorbing chlorine in a first portion of said leach solut