CHARACTERIZATION OF THE MANGANESE OXIDE SCALES FORMED ON ROLLED LEAD ANODES FROM A COMMERCIAL ZINC ELECTRO WINNING OPERATION

摘要

The manganese oxide scales, consisting mainly of MnO_2, characteristically occur in banded colloform structures which adhere to porous layers of PbS04 and PbO_2 that oxidized from the rolled Pb-0.7 percent Ag anodes. Hydrous Mn oxides, Mn_3O_4 and amorphous Mn oxides are believed to be also present. Tiny particles of gypsum, PbSO_4, SrSO_4 and AgCl are entrapped in the colloform masses. The gypsum originated from the Zn electrolyte; strontium carbonate was added to the ZnSO_4 solution to control Pb, and silver originated from the anodes. Some of the colloform bands contain minor amounts of Pb, implying a limited degree of dissolution of the Pb during electrolysis. Other colloform bands incorporate trace amounts of Zn. Colloform structures permeated with silica gel are presumably caused by the high silica content of the electrolyte.