Strategies for Optimal Operation of the Tellurium Electrowinning Process

Empirical models predicting the purity of electrowon tellurium have been developed using data from 36 pilot-plant trials. Based on these models, a numerical optimization of the process was performed to identify conditions which minimize the total contamination in Pb and Se while reducing electrical consumption per kilogram of electrowon tellurium. Results indicate that product quality can be maintained and even improved while operating at the much higher electroplating production rates obtained at high current densities. Using these same process settings, the electrical consumption of the process can be reduced by up to 10 pet by operating at midrange temperatures of close to 50A °C. This is particularly attractive when waste heat is available at the plant to help preheat the electrolyte feed. When both Pb and Se are present as contaminants, the most energy-efficient strategy involves the use of a high current density, at a moderate temperature with high flow, for low concentrations of TeO2. If Pb is removed prior to the electrowinning process, the use of a low current density and low electrolyte feed concentration, while operating at a low temperature and moderate flow rates, provides the most significant reduction in Se codeposition.