Integrated experimental study and thermodynamic modelling of the distribution of arsenic between phases in the Cu-Fe-O-S-Si system

An integrated experimental study and thermodynamic modelling approach has been used in the investigation of the distribution of As between slag and matte in equilibrium with tridymite in the Cu-Fe-O-S-Si system. The experimental technique involves high-temperature equilibration in sealed quartz ampoule, rapid quenching, and direct measurements of phase compositions using microanalysis techniques. Electron Probe X-ray Microanalysis (EPMA) was used to measure major and minor element concentrations in the matte, slag, and solid phases. The experimentally-determined distribution coefficient of As between slag and matte was found to decrease with decreasing P(SO₂) from log L = 0.5 at P(SO₂) = 25 kPa to approximately log L = −4.0 at lowest P(SO₂), corresponding to metal saturation. Thermodynamic model parameters describing As distribution have been derived based on the present and previous data on the slag/matte, slag/metal, and slag/matte/metal equilibria. The thermodynamic model can be used for the evaluation of distribution of As between phases in the high-temperature pyrometallurgical production and refining of copper.