The Bureau of Mines is developing procedures to recover up to 2.5 million pounds of cobalt and 3.5 million pounds of nickel lost annually in processing Missouri lead ores. In the physical separation process, a pb-cu rougher concentrate is separated by wet high-intensity magnetic separation and the magnetic fraction (chalcopyrite concentrate) is reground and floated to produce a high- grade copper concentrate and a tailing product containing over 3.5 pct cobalt and 5 pct nickel. In the hydrometallurgical process, both a co-ni bearing tailing product and lead smelter mattes are leached with manganese dioxide and sulfuric acid to obtain cobalt, nickel, copper, lead, manganese sulfates, and elemental sulfur. At 85 deg. to 100 deg. C, the cobalt, nickel, and copper are solubilized as sulfates leaving a residue of pbso4, sulfur, and gangue. The residue can be returned to a smelter for lead recovery and the soluble metals are recovered from the leach solutions by caustic purification (removal of arsenic and iron) and sequential sulfide precipitations. The products are copper sulfide (62 pct copper) and co-ni sulfide (up to 50 pct combined cobalt and nickel). The manganese is reclaimed from the leach liquor as manganese oxide to be used for recycling.
Proc. 7th Miner. Waste Utilization Symp., Chicago, Illinois, Oct. 20-21, 1980, PP. 127-134