Activities of As, Sb, Bi, and Pb in copper mattes—impurity elimination

Abstract

The theoretical possibilities for the elimination of As, Sb, Bi, and Pb from copper matte were evaluated on the basis of the activity behavior of these impurity elements in the matte, considering removal by purge gas blowing, chlorination, vacuum evaporation, and slagging. The calculations were made assuming equilibrium conditions between the prevailing phases and using different combinations of sulfur, oxygen, and chlorine potentials. Present evaluations show that (1) As can be evaporated from the matte, using moderate amounts of purge gas at a high sulfur pressure of about 10⁻² atm (1013.3 Pa) and a temperature of 1200°C (1473. 15 K); (2) Sb, Bi, and Pb can also be eliminated under similar conditions using a chloridizing purge gas; (3) the purge gas, consumption can be decreased by lowering the total pressure of the system; (4) on a thermodynamic basis, the vacuum evaporation rates of these impurity elements should be much higher from the matte than from copper, the actual differences not, however, having been so apparent in previously published experimental studies, due possibly to kinetic reasons; and (5) the distribution coefficients of As and Sb between slag and matte increase along with the sulfur pressure, although not sufficiently to utilize this phenomenon on an industrial scale.