Effect of oxygen on the Cu-Cu2Se-Ag system

A large percentage of the would's silver supply is produced as a by-product of the copper industry. The silver is found in the copper anodes which are upgraded by electrorefining. The anode composition and the phase distribut ion in the anode affect the electrorefining step and subsequently the separ ation processes for the various elements which are present in the anode. In particular, the distribution of silver and the other precious metals betwe en the copper-rich phase and the copper-selenide rich phase in the anodes h as an effect on their recovery. In the present research the effect of oxygen on the Cu-Se-Ag (Pt, Pd, Au, o r Ni) system was studied. Samples of copper-rich liquid and copper selenide -rich liquid were equilibrated at temperatures in the range of 1130 degrees C to 1223 degrees C. The silver content of both the phases reached a const ant value after about two hours. Also, the oxygen content of the copper-ric h phase reached an essentially constant value. However, the oxygen content of the copper-selenide rich phase continuously increased due to the product ion of oxide phases in the melt. The oxygen content of both phases increase d with the partial pressure of oxygen. At high oxygen potentials the silver distribution ratio between the copper and the copper selenide phases decre ased because of the oxidation of some of the copper selenide to copper oxid e. Silver as either oxide or metal has a much higher solubility in copper o xide than copper selenide and thus the silver distribution ratio decreased. Nickel additions resulted in a significant increase in the oxygen content of both phases. (C) 1999 Published by Elsevier Science Ltd. All rights rese rved.