Abstract: Impurity streams generated during the pyrometallurgy of copper are hydrometallurgically processed at ambient pressure for recovery of primary values in an energy-efficient manner and with the capture and conversion of metallic impurities to states that are acceptable for disposal into the environment. Hallmark features of the various embodiments of this invention include the water leach of flue dust, the extraction of water-soluble copper as a separate product, a controlled acid leach stage in which bismuth is solubilized, the return of copper to the smelting process as a sulfide, the ability to operate the various process stages at essentially ambient pressure, and the gradual reduction in temperature over the course of the process without the use of indirect heating or cooling operations.

Abstract: Highly toxic metallurgical waste materials from copper smelting and/or refining operations are processed on a cyclic basis for recovering copper values therefrom while protecting the environment from contamination. The waste materials, usually smelter flue dust and/or refinery sludge containing copper values and principally arsenic, bismuth, lead, antimony, and cadmium, as toxic values, with or without added sulfuric acid, are reacted in an autoclave at an overpressure atmosphere of O.sub.2. The resulting solution, pregnant with copper and still containing a significant amount of arsenic, i.e. from about 0.5 to about 2.0 grams per liter, is subjected to copper cementation on metallic iron to recover copper and to provide iron values in the solution while substantially eliminating residual toxic constituents, surprisingly without the evolution of arsine gas. The copper-barren but iron-containing solution is then recycled to the leaching step.

Abstract: Molybdenum is selectively extracted from an aqueous solution containing various other metal values, e.g. copper, arsenic, iron, bismuth, antimony, tin, and lead in addition to molybdenum. The molybdenum-bearing solution is adjusted to a pH of about 2.0 or less, and, then, intimately contacted with an organic extracting solution containing an alpha-hydroxy oxime. The loaded organic phase, containing extracted molybdenum values, is separated from the aqueous raffinate, and the molybdenum values contained in the organic phase are stripped therefrom using an aqueous stripping solution containing ammonium hydroxide. The efficiency with which the molybdenum is stripped from the loaded organic solution is poor unless nonylphenol is present in the organic solution as it is being stripped. The nonylphenol can be added to the system anytime prior to the ammonium hydroxide stripping step, e.g.