Copper solubility in FeO−Fe2O3−SiO2−Al2O3 slag and distribution equilibria of Pb, Bi, Sb and As between slag and metallic copper

Abstract

The solubility of copper in silica-unsaturated fayalite slags containing an average of about 8 pct Al2O3 was measured by equilibrating the slag with metallic copper at 1200 and 1300°C under CO−CO2 atmospheres with oxygen potentials in the rangepO2=10−6 to 10−11 at. The copper solubility, which was found to be dependent upon the oxygen potential, was expressed in terms of the Fe/SiO2 ratio, temperature and activity of CuO0.5. The distribution of Pb, Bi, Sb and As between copper and slag was measured concurrently by doping the metallic copper. The distribution coefficient was defined by (mole fractionX in metal)/(mole fractionX in slag) assuming the FeO−FeO1.5−SiO2−AlO1.5−CuO0.5 system slag. The distribution coefficient for lead was found to be a function of the oxygen potential, and a PbO activity in the slag of 0.07±0.01 was measured over the range of 1200 to 1300°C. Dissolution of Bi, Sb and As in the slag was found to be independent of the oxygen potential suggesting atomic rather than oxidic dissolution. The observed distribution coefficient for Bi and Sb was 30. The observed distribution coefficient for As was 300, but this is subject to error up to one order of magnitude due to analytical uncertainty of slag. The data are useful in analyzing minor element behavior in copper smelting processes.