A fundamental study of the reductive leaching of chalcopyrite using metallic iron part I: kinetic analysis

The reductive leaching (decomposition) of chalcopyrite was studied in an attempt to find a suitable hydrometallurgical method for copper recovery. A chalcopyrite concentrate was leached under reducing conditions, where metallic iron served as a reductant. The studied parameters include agitation, temperature, particle size, acidity, and reductant and chalcopyrite amounts. The experimental results showed that it is possible to convert the refractory chalcopyrite to a rich copper sulfide (chalcocite), which is amenable to further treatment. The results of kinetic analysis of the leaching data under various experimental conditions indicated a reaction controlled by the solution transport of protons through the product layer, with an activation energy of 33.9 kJ/mol for sulfate media and 22.4 kJ/mol for chloride media. Based on the shrinking core model, the following rate equation was established for sulfate media: 1 - 3(1 - X-b)(2/3) + 2(1 - X-b) = k(o)'/R-2[H+]exp(-22,423/R'T)t and for chloride media, 1 - 3(1 - X-b)(2/3) + 2(1 - X-b) = k(o)(n)/R-2[H+]exp(-22,423/R'T)t The results of the kinetic analysis were utilized in developing a simple process for producing copper super-concentrates. The process still needs further investigation to demonstrate its viability. (C) 2002 Elsevier Science B.V. All rights reserved.