A potential method for arsenic removal from copper concentrates

This paper presents results for a project demonstrating a new technology for arsenic removal from copper concentrates. The problems concerning pyrometallurgical processing of copper concentrates with high arsenic content are presented in the first part of the paper. Possible solution of the problem by leaching of natural enargite crystals with sodium hypochlorite, under alkaline oxidizing conditions, with enargite converted into crystalline CuO and the soluble arsenic forming AsO43- was experimentally investigated and results presented in the second part of the paper. Kinetic parameters were calculated for both isothermal roasting and enargite leaching. According to the Arrhenius diagrams, the activation energy of the process, under isothermal conditions was calculated. The kinetic equation for desulfurization during isothermal roasting was found to be: 1-1-α1/32=k·t=5.0593·exp-4571T·t, with activation energy of 38 ± 3 kJ/mol. Kinetic equation describing arsenic removal, during same process, was: 1-2/3α-1-α2/3=k·t=2.7322·exp-4330T·t, with activation energy 36 ± 5 kJ/mol. For the process of enargite leaching kinetic equation was:1-2/3α-1-α2/3=k·t=837.87·exp-3608T·t, with activation energy of 30 ± 1 kJ/mol.