New Process for the Precipitation of Sb and Bi from Copper Electrolytes with PbO2

"This paper presents a new process for the precipitation of Sb and Bi present in copper refinery electrolytes in the presence of Pb02 (Chilean Patent No. 45,037). To establish the conditions under which the precipitating compounds form, it was necessary to evaluate the amount of PbCh consumed, antimony extraction efficiency, precipitate stability, reaction kinetics, diffraction analysis and X-ray fluorescence, separation of size, plus observation of the precipitates in the electron microscope. Preliminary tests were carried with synthetic copper refinery electrolyte, and then the final testing was done with electrolytes from Chilean refineries. This process provides a real alternative for the treatment of copper refinery electrolytes for the control of Sb and Bi in solution; it is very simple to operate and is low cost compared with competing processes.Introduction.A high quality copper cathode implies a cathode free of impurities. The electrorefining process seeks to eliminate these impurities from the copper anode (99.5% purity) by its dissolution in an acid electrolyte using chemical and electrochemical reactions. As a result of this process, a cathode (99.99% purity) is obtained. If the concentration of impurities in the electrolyte, from the dissolved anodes, begins to increase; particularly if the antimony concentration in the electrolyte increases up 500 ppm, the formation of floating slimes which are a major cause of contamination of the cathode is favoured. The most important impurities from the point of view of their effect on the quality of the cathode copper, are Ag, As, Sb, Bi, Pb, Se and Te. Silver is necessary for the control of Se and Te. To control all of these impurities, it is necessary to establish different methods or parameters of control in copper electrorefining. These parameters are anode composition, additives, purification of the electrolyte, current density, acidity, etc."