Abstract
Present society challenges, including metal scarcity, recycling, and environmental restrictions, resulted in the increased complexity and variability of metallurgical feed streams. Metallurgical processes involving complex lead and copper-containing slag and matte phases are now commonly used in response. Optimization of existing and development of new metallurgical processes require fundamental information on slag−matte phase equilibrium. Development of the experimental methodology for the characterization of slag−matte phase equilibrium is presented in the paper. Following a detailed analysis of the potential reaction pathways, experimental techniques have been developed that enable accurate measurement of slag−matte phase equilibrium in the Pb-Fe-O-S-Si system. The application of the techniques has been demonstrated for two important sets of conditions: (i) Condensed phase equilibrium for the slag−matte−metal−tridymite subsystem; and (ii) Gas−slag−matte−tridymite equilibrium at fixed oxygen and sulfur partial pressures. The experimental methodology involves high-temperature equilibration of synthetic samples, fast quenching, and microanalysis of the compositions of phases using electron probe X-ray microanalysis (EPMA). The experimental results are not affected by the changes in the bulk composition of samples during equilibration; this helps to overcome the significant barriers previously encountered in undertaking accurate measurement and characterization of these systems.