Slurry electroleaching, which produces manganese dioxide from low grade manganiferous raw materials, is noteworthy.
Studies on slurry electroleaching made a start in the latter half of 1960s. Since then, in-depth researches based on slurry electroleaching have been carried out on the treatment of galena, copper sulfide ores and manganese ores. As a result, many successes have been made so far.
However, few studies and applied cases with regards to the industrial method of processing low grade manganiferous raw materials (below Mn 10%) into manganese dioxide have been reported.
DPRK has little amount of Mn raw materials of over 20%. Instead, it has a great deal of wad clay. In order to meet the domestic demands, the problem of processing wad clay must be solved. In addition, the wad clay in our country contains lots of slime. According to some preliminary experiments, slime leaked into the anode diaphragm during the process of slurry-electroleaching, thus dramatically decreasing the rate of the content of manganese dioxide.
Based on the preceding research results, Jon Yong Nam, a researcher at the Faculty of Metallic Engineering, applied slurry electroleaching method (diaphragm electrolysis) to the low-grade wad clay (Mn 4~6%) which is deposited in the central region of DPR Korea in order to obtain high-grade manganese dioxide of over Mn 40%.
He observed the effects of the temperature, current density, ratio of liquid to solid (L/S), time and coagulant agent through the basic experiment on slurry electro leaching of the wad clay. He determined the optimum conditions as follows: current density 150~200 A/m2, temperature > 65℃, L/S = 10 : 1, time 1.1 times the theoretical leaching time and amount of the coagulant agent 50 g/t. Under these conditions, the leaching rate was above 95% and the content of Mn in anodic electrodeposits was 45%.
You can find the details in his paper “A Study on the Extraction of Manganese from Wad Clay by Slurry Electrolysis” in “Russian Journal of Non-Ferrous Metals” (SCI).