Leaching of Cobalt-Rich Ferromanganese Crust with Ammoniacal Solutions Using Ammonium Sulfite and Ammonium Thiosulfate as Reducing Agents

摘要

Preferential ammoniacal leaching of Co, Ni and Cu from cobalt-rich ferromanganese crust under reducing conditions was performed using ammonium sulfite and/or ammonium thiosulfate as reducing agents. The effects of reducing agent concentration, initial pH, leaching time, temperature and the combined concentration of ammonium sulfite and ammonium thiosulfate on the extraction of Co, Ni, Cu, Mn and Fe were investigated. The extraction of Co, Ni and Cu with ammonium sulfite was better than that with ammonium thiosulfate. When ammonium sulfite was used as the reducing agent, Mn was precipitated and appeared in the residue as (NH_4)_2Mn(SO_3) centre dot H_2O.