Hydrometallurical recovery of copper and zinc from complex sulfide ores

A continuous hydrometallurgical process for single stage conversion of copper sulfides or zinc sulfides from ores containing copper sulfides, zinc sulfides, or both, and that are contained in finely divided materials into recoverable precipitates while minimizing emissions of nitrogen gas and N.sub.2 O, the process comprising:

• contacting finely divided materials selected from the group consisting of an ore, a concentrate, and a mixture of an ore and a concentrate, and in which the ore or concentrate contains compositions selected from the group consisting of a copper sulfide, a zinc sulfide, and mixtures of copper sulfide and zinc sulfide, with sulfuric acid and nitric acid to form a reaction mixture of the materials and the sulfuric acid and nitric acid;
• while concurrently mixing and maintaining the mixture at a temperature of between about 110.degree. C. and 170.degree. C.;
• and while
• introducing a source of oxygen to the mixture;
• wherein the sulfuric acid is present in a volume amount of between about 40% and 65% based on the volume of the reaction mixture;
• and
• wherein the nitric acid is present in a ratio of between about 0.5 and 3.0 mole of nitric acid per mole of sulfide in the finely divided materials, the amounts of sulfuric acid and nitric acid present in the mixture being sufficient to form a light colored precipitate of water soluble sulfate salts of copper sulfate or zinc sulfate or both, and a dark colored precipitate of sulfur and gangue;
• and
• wherein the amount of introduced oxygen is sufficient to form regenerated nitric acid from the nitrogen-containing by-products.