Abstract: The present process involves an improvement in the hydrometallurgical recovery of metal values from metal bearing sources such as ores and the like. The desired metal values are recovered by subjecting a metal bearing source to a reductive roast in a reducing atmosphere after having treated said source with at least one additive. Following the reductive roast the reduced metal bearing source is cooled and extracted by a leaching operation. The separation of various metal values in the metal bearing source may be effected by adding a solid adsorbent to the leach solution whereby selective metal ions are adsorbed thereon. The improvement in the present process comprises pretreating the solid adsorbent prior to use thereof with an acid thereby increasing the loading capacity of the metal ions in the adsorbents as well as kinetics of metal adsorption.

Abstract: The present process involves an improvement in the hydrometallurgical recovery of metal values from metal bearing sources such as ores and the like. When subjecting a metal bearing source to a reductive roast in a reducing atmosphere followed by cooling the reduced metal bearing source, extracting the cooled source and recovering the resultant nickel value, it is possible to utilize a smaller amount of an additive which assists in the recovery of metal values by scrubbing the off-gases from the reductive roast utilizing a fresh metal bearing source feed as the scrubbing material.

Abstract: Lead values may be recovered from lead bearing sources such as lead sulfide in improved purity. The improved purity is obtained by subjecting soluble lead halides formed by the halogenation of lead sulfide and brine leaching the chlorinated product prior to treatment with a reducing agent followed by filtration and further treatment with an oxidizing agent whereby impurities as represented by other metal values are removed.

Abstract: Metallic lead is obtained from lead sulfide ores or concentrates by subjecting the concentrate to a drying step followed by halogenating the dried concentrate in a dry atmosphere at a temperature in the range of 90.degree. to about 120.degree. C. Thereafter the halogenated mixture is subjected to a water wash and leached with a brine solution. The brine solution is then filtered to separate elemental sulfur and residue from the solubilized lead halide, the latter being then crystallized and subjected to fused salt electrolysis to recover metallic lead.

Abstract: Chromium values may be recovered from the chromium bearing ores or sources by subjecting the chromium bearing source to a roast in the presence of sulfuric acid and an oxidant which contains manganese compounds at temperatures ranging from about 200.degree. to about 500.degree. C. followed by leaching, separation and solvent or ion exchange extraction whereby chromium is selectively extracted and recovered.

Abstract: Manganese values may be recovered from manganese bearing sources by subjecting said source to a roast in the presence of sulfuric acid and a reductant which comprises a chromium-containing compound at temperatures ranging from about 200.degree. to about 500.degree. C. followed by leaching, separation, solvent extraction or ion exchange whereby manganese is extracted, followed by separation and recovery of the manganese.