Asarco LLC

Adrian E Albrethsen

William H Wetherill

Mamdouh M El Tawil

Max L Hollander

A process is provided for the reduction roasting of ores using a C.sub.2 to C.sub.8 hydrocarbon. The process is particularly applicable to manganese dioxide containing ores and provides enhanced reduction of the manganese to lower oxidation states at low operating temperatures for manganese dioxide ores and provides increased silver recoveries from refractory manganese-silver ores.

Reduction roasting of metal ores

Tetrahedrite ore concentrate, sodium sulfide added as such or formed in situ, calcium values preferably supplied as lime, and a reducing agent, e.g. coke, are smelted for a period sufficient to convert a major portion or substantially all of the antimony to a water-soluble sodium compound of antimony and sulfur and a major portion or substantially all of the arsenic also contained in the concentrate to a water-insoluble calcium compound of arsenic and oxygen. The sodium sulfide is incorporated into the charge for the smelting in an amount sufficient to convert at least a major portion of the antimony into the water-soluble sodium compound of antimony and sulfur; and the lime is incorporated into the smelting charge in amount sufficient to convert at least a major portion of the arsenic into the water-insoluble calcium compound of arsenic and oxygen. A soda matte obtained from the smelting and containing the soluble sodium compound of antimony and sulfur and the insoluble calcium compound of arsenic and oxygen as well as a water-insoluble sulfur compound of copper is leached with an aqueous liquid, ordinarily water, to dissolve substantially only the soluble sodium compound of antimony and sulfur. The aqueous leach solution containing the soluble sodium compound of antimony and sulfur is separated from an insoluble leach residue containing the insoluble calcium compound of arsenic and oxygen and the insoluble sulfur compound of copper. BACKGROUND OF THE INVENTION

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Bridgewater, NJ, United States of America

Adrian E Albrethsen