Complex evaluation and development of electrolytic tin refining in acidic chloride media for processing tin-based scrap from lead-free soldering

Abstract

Different ways of investigation were applied to address the main difficulties of electrolytically refining the tin-based lead-free soldering waste materials in chloride solutions. The characteristics of electrorefining and the phenomena of electrocrystallisation have been targeted by examining the electrode processes with different copper and silver concentrations in the anodes. Galvanostatic experiments were carried out using a specially developed system detecting the changes in the electrode masses continually, complemented by the recording of the electrode potentials. In order to clarify the main cathode and anode processes, further investigations were carried out by the potentiodynamic technique. Galvanostatic results pointed out the causes of current losses and rough deposit structure. Potentiodynamic examinations have demonstrated the strong influence of material transport on the electrode processes. Nevertheless, with a quasi-optimised procedure, cathode tin of higher purity than technical standards could be achieved from the soldering waste material in a conventional cell.