INVESTIGATIONS INTO THE LEACHING BEHAVIOR OF FINELY GROUND ZINC BLEND AND COPPER PYRITE FLOTATION CONCENTRATES

Ultra fine grinding tests with technical sphalerite- and chalcopyrite concentrates in a stirring ball mill reveal that even after short treatment times a significant specific surface area increase can be observed. Beside the growing surface area as an effect of the grinding treatment, lattice distortions have been noticed by x-ray-analysis. Leaching tests with Ferrisulfate of ultra fine ground sphalerite-concentrate in a stirring ball mill indicate that a 95% extraction of Zinc can be achieved in 60 min leaching time after 15 min grinding. Referring to the chalcopyrite-concentrate, a 160 min grinding results in a 95% Cu-extraction after 90 min leaching time. Considerations about the dissolution kinetics show that the diffusion of the metal ions through the build up layer of elemental sulphur is rate determining for the extraction process.