Electrochemical prodn. of manganese di:oxide - from acidic manganese sulphate soln. using coated titanium anode, used as active material for positive electrode of prim. cells

摘要

In the electrochemical prodn. of MnO2 by electrolysis of an aq. soln. contg. 100-150 g/l MnSO4 and 20-30g/l H2SO4 at 90-95 degrees C and an anodic current density of 80-100 A/m2, the Ti anode used as a 50-100 mu m thick Ci carbide coating. The cathode pref. consists of Cr-Ni steel, contg. 18-23 (wt.)% Cr and 20-28% Ni and alloyed with Cu, Mo, Ti, Si and Mn. The MnO2 produced is used as active material for the positive electrode of prim. cells. The carbide coating reduces the bath potential and increases the current yields to 97-99%. The prod. contains 89-92 wt.% MnO2. In an example, the anode consisted of a Ti rod with a carbide coating produced by placing the rod in a sheath with pure C. black and heating 2 hrs. at 900-1100 degrees C in pure H2. Electrolysis of a soln. contg. 100g/l MnSO2 and 30g/l H2SO4 at 90-95 degrees C, 150 A/m2 at the cathode, 80 A/m2 at the anode and 1.8-1.9 V for 350 h. gave 90.3% pure MnO2, with a current yield of 98.5%.