Crushing and Grinding of Electrodeposited Manganese Dioxide

Electrolytic manganese dioxide, for use as an efficient depolarizer in dry cells, is produced by the electrolysis of a solution of manganese sulphate and sulphuric acid at a temperature of 95°C. As the electrolysis proceeds, manganese dioxide is deposited in thick adherent form on the anodes. The anodes are taken out when the deposited manganese dioxide attains a thickness of 15-25 mm in about 10-15 days on continuous operation. The thickness of the EMD deposited on the anode depends on the current density and the duration of electrolysis. The anodes after taking out of the electrolytic cells are washed thoroughly with water to remove the carried over electrolyte and hot air dried. The sudden fluctuation in temperature, on lifting the anodes from the hot electrolytic cell and washing, cracks the EMD deposit. After drying, the deposits are easily stripped from the anodes by mild striking.