Thermodynamic analysis of reduction in copper slag by biomass molding compound based on phase equilibrium calculating model

Abstract

Copper slag is a good valuable material resource with high iron content in the form of fayalite. Biomass as reduction reducer was proposed in this paper. For the basic research of the reduction in biomass, the biomass reducer was simplified as molding compound C, CO, H2 and CH4. The reactions of 2FeO·SiO2 with C, CO, H2 and CH4 could proceed spontaneously with the addition of CaO. The Gibbs free energy is decreased significantly by addition of CaO. The equilibrium compositions of products were calculated and analyzed combing with 19 basic reactions. Beginning temperature of C, CO, H2 and CH4 is 900, 623, 567 and 511 K, respectively The reduction degree of C, CH4, H2 and CO is 1, 0.851, 0.695 and 0.452, respectively, at 1773 K when the reducer addition ratio is 1.0 calculated by phase equilibrium calculating model. Direct reduction reaction of copper slag dominates at higher temperature, and temperature region of 700–1173 K is the transformational zone. Indirect reduction index curves are in the shape of reverse ‘S,’ and the higher temperature is in favor of indirect reduction in copper slag. There is a steady increase in reduction degree with the increase in reducer. Reduction reaction path of copper slag by C, CO, H2 and CH4 is established.