Anaconda Copper Company

Arbiter Previously known as the Sherritt-Gordon ammonia process. A process for leaching copper from sulfide concentrates, using ammoniacal ammonium sulfate solution at 85°C and relying on air oxidation. Copper is produced from the leachate by solvent extraction and electrowinning. Sulfur is recovered as ammonium sulfate. Operated on a large scale by the Anaconda Copper Company in Montana from 1974 to 1979. See Sherritt-Gordan. 

Three major companies accounted for the bulk of US arsenic production in the first half of the twentieth century American Smelting and Refining Co. (ASARCO both copper and lead smelting in several domestic plants), Anaconda Copper Co. (copper smelting), and US Smelting Co. (lead smelting), along with several minor producers. Notably, from 1974 to 1985, the domestic supply of arsenic was controlled by ASARCO, and since 1985 by imports primarily from China, Chile, and Mexico (Mineral Commodity Summaries, 2004). 

A major source of water for leaching is the normally acidic run-off water from the mining operation itself. O Leary (02) describes a technique of cleaning up to 900 gal/min of mine and tailings water at the Butte operation of the Anaconda Company. The suspended solids, which at times are in excess of 2% by weight, are equivalent to about 50 tons of mud per day. Since copper is recovered from this stream by precipitation and the barren liquor is used to leach the mine w aste dumps, solids, and colloidal materials have to be removed. With a flocculant, a 98% reduction in solid content is attained with a feed stream containing 0.22% solid. 

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