The leaching of tetrahedrite in ferric chloride solutions

This paper presents a study of the kinetics of the leaching of tetrahedrite in FeCl3-NaCl-HCl solutions for temperatures between 60 degrees C and 104 degrees C and ferric ion concentrations of 0.001 to 1 M at atmospheric pressure. The shrinking core model was applied to the results. The calculated activation energy is 65 +/- 6 kJ/mol; the order of the reaction with respect to ferric ion is 0.35 +/- 0.03; and the apparent rate constant is proportional to the inverse of the: mean particle size. These results show that, for temperatures below the normal boiling point of the solution, the leaching of tetrahedrite is reaction controlled. From the analyses of the solutions and X-ray and microprobe analyses of the solid residues, it was concluded that the leaching of tetrahedrite involves the complete breakdown of the sulphide structure. (C) 2000 Elsevier Science B.V. All rights reserved.