FACTORIAL-EXPERIMENTS FOR SELECTIVE LEACHING OF ZINC-SULFIDE IN FERRIC SULFATE MEDIA

The zinc-recovery results obtained in leaching tests run on a complex sulphide ore of Caribbean origin have been statistically processed. Th e raw material contained 6.95% Zn, 2.41% Pb and traces (0.05%) of Cu, The study was conducted by means of consecutive factorial plans which permitted determination of the manner in which the leaching was influe nced by the following factors: (1) oxidizing agent (Fe-2(SO4)(3)) conc entration; (2) temperature; (3) ore particle size characteristics; and (3) solid/liquid ratio. A regression equation was calculated by the r esults obtained from the tests; this permitted the derivation of a res ponse surface which provides zinc recovery levels in relation to the l evels of the factors adopted in the experiments. It is important to un derstand the parameters which exert most influence on zinc recoveries during leaching, especially when the presence of finely distributed po lluting agents in the useful phase, pyrite in this case, prevents zinc enrichment by the usual physical means. (C) 1998 Elsevier Science B.V . All rights reserved.