Study on Self-Catalysis Reduction Leaching of Ocean Co-Mn Polymetallic Ores in Ammonia Solution

Copper ions can catalyze reduction of manganese dioxide by carbon monoxide in ammonia solution. The paper studied on the reduction ammonia leaching process of ocean Co-Mn polymetallic ores, such as the polymetallic nodules and the cobalt-rich crust. The self-catalysis reduction ammonia leaching was carried out, in which the copper ion leached out of the raw materials, the Co-Mn polymetallic ores, was taken as the catalyst and CO as the reducing agent. The concentration of copper in the leaching solution has great effect on the oxidation-reduction reaction rate, and the reaction rate is very fast when the concentration of copper is more than 8g/L. By a suitable mixture ratio of polymetallic nodules to cobalt-rich crusts, the self-catalysis reduction ammonia leaching could be realized. At the condition that polymetallic nodules to cobalt-rich crust 3:1, temperature 45° C and the leaching solution with more than Cu 9g/L, Ni 13g/L, and Co 3.5g/L, the average leaching extractions of nickel, cobalt and copper are 94%, 86% and 93% respectively in continuous leaching process.