Electrolytic manganese metal production from manganese carbonate precipitate

摘要

The recovery of manganese metal from manganese carbonate precipitate by leaching-purification-electrowinning was studied. The manganese carbonate precipitate from Baja Mining Corp.'s El Boleo project was readily leached into acidic ammonium sulfate solution. The manganese extraction reached 99.7%. The manganese leachate was purified using ammonium sulfide to remove harmful impurities (Ni, Co, Cd, Cu and etc.). Manganese electrowinning was conducted in a diaphragm cell designed to eliminate edge effects and improve manganese deposition. The addition of polyacrylamide polymer had a significant leveling effect on manganese electrodeposition. However it increased the deposit internal stress and even resulted in cracking of manganese deposits at a high dosage. With increasing polyacrylamide polymer concentration, current density, and pH, the manganese current efficiency first increased, reached a maximum value and finally decreased. The manganese current efficiency decreased with increasing deposition time as the deposit became rougher and the real current density deviated from its ideal value. A reasonable catholyte circulation rate is important to maintain the optimum manganese electrodeposition. The presence of chloride in solution has a little effect on manganese deposition in its concentration range from 0 to 2 g/L The diaphragm selection as an important part of the cell design was analyzed. (C) 2016 Elsevier B.V. All rights reserved.