Chemical degradation of magnesia-chromite refractory used in the conversion step of the pyrometallurgical copper-making process: A thermochemical approach

Abstract

Refractory wear in furnaces is a key cost driver in pyrometallurgical processes, leading to periodical relining that involves maintenance and increased operational costs. One of the main factors in refractory wear is the chemical attack by the molten phases from the bath. This chemical interaction generates new phases in the refractory, producing different properties and causing spallation due to the aggregate effect of the thermal and mechanical shocks during operation.This paper uses thermodynamic databases (Fact Sage® software) to study the interaction between the molten phases and the magnesia-chromite refractory in the conversion step of the copper-making process. Input data were taken from an industrial furnace at Atlantic Copper S.L.U. (Huelva, Spain) and the calculations were conducted at different temperatures and oxygen partial pressures (pO2). These thermochemical calculations allow the chemical degradation of the refractory to be evaluated.The results show the characterization of the new phases (mainly spinel and olivine) formed after the chemical interaction between the molten phases and the refractory. Since the composition and mass distribution of the new phases change, the degree of refractory wear is calculated for each scenario designed.