COBALT BEHAVIOR DURING NATURAL AND TECHNOGENIC OXIDATIVE LEACHING OF Co-CONTAINING PYRITES ( Letnee chalcopyrite deposit, Southern Urals )
O.L. Gas’kova, E.V. Belogubb, and D.V. Makarovc
a V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
b Institute of Mineralogy, Ural Division, Russian Academy of Sciences, Miass, Chelyabinsk oblast, 456317, Russia
c I.V. Tananaev Institute of Chemistry and Technology of Rare Elements and Minerals, Kola Scientific Center, Russian Academy of Sciences, 26a ul. Fersmana, Apatity, Murmansk oblast, 184209, Russia
Keywords: Cobalt, pyrite deposits, oxidation zone, sulfate minerals, oxidative leaching, thermodynamic model
Pages: 176-185
Abstract
Cobalt behavior during the oxidation of sulfide ores, unlike that during the oxidation of Co ores, is poorly known. Moreover, cobalt sulfates are rare in the world. Complex hydrous Co-containing and cobalt sulfates have been found in technogenic zones at the Letnee chalcopyrite deposit (Southern Urals). They have been identified at pit bottoms, in the ore stockpile, as well as directly on ore fragments and the evaporation barriers of underdump water puddles. The paper reports the first experimental data on the oxidative leaching of Co-containing sulfide ores in the laboratory. Also, parts of a thermodynamic model for behavior in oxidized zones are presented.
Experiments have revealed an increase in acidity up to pH = 4.14, along with transport of sulfate sulfur and metals into solution. They suggest acid mine drainage during the development of the Letnee deposit. The published stability diagrams for hydrous Cu, Mg, Zn, Co, and Ni sulfates were analyzed and compared with mineralogical finds in a technogenic oxidized zone. This made it possible to explain the precipitation sequence of minerals from solutions during their concentration by evaporation. As salts of these elements are highly soluble, significant contents of toxic metals inevitably remain in equilibrium solution, necessitating additional waste-water treatment (for example, creating sorption geochemical barriers). Therefore, the paper describes regularities in Co behavior during its sorption on solid phases.
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