Copper extraction from white metal by pressure leaching in H 2SO 4–FeSO 4–O 2

Abstract

In this investigation, pressure leaching experiments were carried out in H 2SO 4–FeSO 4–O 2 and H 2SO 4–O 2 media to clarify the role of iron in the leaching of white metal produced in a Teniente Converter reactor. The dissolution rate of copper was studied in the range of 80 to 150 °C, using oxygen partial pressure from 203 to 1013 kPa. The results on the dissolution of white metal in H 2SO 4–O 2 and H 2SO 4–FeSO 4–O 2 media indicated that white metal leaches in two stages and iron in the leaching solution affects drastically the rate in the range of 80 to 150 °C. In the presence of iron at temperatures below the melting point of elemental sulfur, the leaching rate, particularly the rate of the second stage increases drastically as compared to the case in the absence of iron. The rate increase is due the indirect leaching mechanism involving Fe 3+ ions, which leach the white metal at a faster rate than O 2. The kinetics of copper dissolution from white metal was analyzed and activation energies for the two-stage leaching of white metal in H 2SO 4–FeSO 4–O 2 medium were calculated as 76 kJ/mol and 32 kJ/mol for the first and second stages, respectively.