Other

Ernest Peters

Robert N O'Brien

Morris J Beattie

Rein Raudsepp

A hydrometallurgical process for converting zinc sulfide in an ore containing zinc sulfide, said zinc sulfide being chemically converted at elevated temperatures to ZnSO.sub.4.xH.sub.2 O which crystallizes substantially in the monohydrate formas ZnSO.sub.4.H.sub.2 O in a conversion solution having a high concentration of H.sub.2 S.sub.4. The process comprises: i) contacting the zinc sulfide of the ore with the conversion solution which comprises a concentration of sulfuric acid selected from the range of about 45% by weight up to about 70% by weight of the conversion solution and at the elevated temperature in the range of 90.degree. C. to less than boiling point of the conversion solution for the selected concentration of sulfuric acid; ii) maintaining the conversion solution at the elevated temperature and at the range of concentration of the sulfuric acid to ensure continued formation of the crystals of ZnSO.sub.4.H.sub.2 O until substantially all available ZnS is chemically converted; and iii) separating the ZnSO.sub.4.H.sub.2 O crystals and remaining solids of the ore from the conversion solution.

Preferential hydrometallurgical conversion of zinc sulfide to sulfate

A process for the hydrometallurgical recovery of precious metal from an ore or concentrate containing at least some arsenopyrite or pyrite. The process comprises forming in a common volume space a gas phase and a liquid slurry comprising the ore or concentrate as the solid phase and acid and water as the liquid phase of the slurry effecting in the slurry an oxidation-reduction reaction between the arsenopyrite or pyrite and an oxidized nitrogen species in which the nitrogen has a valence of at least plus 3 thereby solubilizing in the liquid phase the arsenic, iron and sulphur in the arsenopyrite, or the iron and sulphur in the pyrite, and producing in the liquid phase nitric oxide in which the nitrogen has a valence of plus 2; releasing at least part of the nitric oxide from the liquid phase into the gas phase oxidizing the nitric oxide in the gas phase, to form an oxidized nitrogen species in which the nitrogen has a valence of at least plus 3; and absorbing the oxidized nitrogen species into the slurry wherein the oxidized nitrogen species become available for the oxidation-reduction reaction. The resultant treated slurry is subjected to a solid-liquid separation to produce a solid residue and a liquid fraction. Precious metal is recovered from the solid residue. The liquid fraction is recycled in the process.

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Vancouver, Canada

Ernest Peters