Recovery of Nickel and Cobalt from Dimethyldithiocarbamate Precipitation of Pyrolusite Leaching Process

Dimethyldithiocarbamate precipitation is a secondary resource containing nickel and cobalt, which are formed by adding sodium dimethyldithiocarbamate to purify the neutralized filtrate of pyrolusite reductive leaching process. The extraction of nickel and cobalt from dimethyldithiocarbamate precipitation was investigated using nitric acid as oxidant in dilute sulfuric acid medium in this paper. The effects of concentrations of nitric acid and sulfuric acid, leaching temperature as well as reaction time were discussed. The results showed that high nickel and cobalt recovery could be obtained by analyzing the leaching efficiencies of nickel and cobalt during the leaching process. The optimal leaching condition was 1.47 mol/L H2SO4 and 1.16 mol/L HNO3 for 30 min at 45 °C while using particles smaller than 0.420 mm. And the leaching efficiencies were 98% for Co and 95% for Ni, respectively.