Equilibria of Iron Silicate Slags for Continuous Converting Copper-Making Process Based on Phase Transformations

Abstract

Great merits have been identified for the continuous production of copper, and different continuous converting (CC) processes are developed and increasingly used for copper making. For the CC process, the equilibria of multiple phases including iron silicate slags, spinel, gas, blister, and white metal phases are clarified under a high-level P(SO2) 0.4 atm in the temperature range of 1523 K to 1573 K (1250 °C to 1300 °C). The microstructures and chemical compositions of various phases in the equilibrium system after high-temperature experiments are quantified using an electron probe X-ray micro-analyzer (EPMA). Both P(O2) and P(SO2) are accurately controlled, and based on the phase transformations in the CC system equilibrated under P(O2) of 10−5, 10−5.5, 10−5.75, and 10−6 atm, the required P(O2) range for the CC process is firstly obtained at each operational temperature. Accordingly, the phase equilibria of iron silicate slags are derived, including the equilibrium Fe/SiO2 ratio and “Cu2O” content in the liquid phase versus varying operational temperatures. The results obtained here thus provide important clues for the development of CC copper-making process.