The anode-support system: an alternative for the electrorefining of tin in sulphuric acid medium

Abstract

This paper describes a study of the application of an anode-support system to the electrorefining of tin in sulphuric acid medium. The authors have established that it is feasible to utilize a metallic basket of AISI-316 stainless steel mesh as the anode-support, with granules of 97% tin inside the basket. It is possible to utilize the anode-support system under the same conditions used for the industrial electrorefining of tin with conventional cast anodes. In a comparative study of experiments for the electrorefining of tin (97%) artificially contaminated with lead (3%), antimony (3%) or lead-antimony (1.5%–1.5%), it has been established that the anode-support system has a significant advantage over the traditional system. In fact, electrolyses of 10 days duration can be carried out continuously using the anode-support system, with the cell voltage remaining practically constant. In electrolyses using the traditional cast anodes it is necessary to interrupt the process every one or two days to eliminate mechanically the passivating film (PbS04 and Sb oxides) that covers the electrode and increases the anodic overpotential.