Direct reduction of copper-iron-silicon oxide melts

The selective reduction smelting of Cu2O in Cu2O-FeO2-SiO2 melts has been studied at laboratory level, using as a feed a dead roasted calcine from a copper concentrate. The purpose of the study was to evaluate the kinetic and mechanisms of the indirect reduction with CO and the direct reduction with graphite from 1260 degrees C to 1350 degrees C. The reduction rate by CO was found to be 10(-2) to 10(-1) mole Cu2O m(-2)s(-1). The graphite reduction macrokinetics for FeO and Fe2O3 containing melts, was found to be a first order reaction with respect to the Cu2O concentration, with a kinetic constant of 10(-4) to 10(-3) s(-1). The reduction rate was not sensitive to temperature nor to stirring, in the range studied, The measured reduction rate is almost one order of magnitude larger than the observed rate for the direct reduction of FeO.