siding. THE EFFECT OF CERTAIN VARIABLES ON THE ELECTRODEPOSIT ION OF MANGANESE 1

An electrolytic manganese pilot plant having a present daily capacity of 2,400 lb. (1,090 kg.) has been operated by the U. S. Bureau of Mines for the past 2 ~ years. This paper records the results obtained on the effect of certain variables on the electrodeposir of man-ganese, namely, time of deposition, cathode current density and cell temperature. It was found that the current density and time of deposi-tion could be varied over a wide range, with only a slight variation in current efficiency. The power requirement, however, does vary con-siderably. A cell temperature of 35 ~ was found to be the optimum for operation. A decrease in temperature below 35 ~ has only a slight effect on current efficiency and greatly increases the voltage. An increase above 35 ~ results in a nodular and arboreal deposit with rapid lower-ing of current efficiency. The optimum conditions for the operation of electrolytic manganese cells were found to be 45 to 50 amp./sq, ft. (4.9 to 5.4 amp./dm. ~) cathode current density; 35 ~ cell temperature; and 32-hour deposition time