Modification of Structural-Textural Properties of Sulfide Minerals at Polymetallic Concentrate Leaching with Sulfuric Acid and Hydrogen Peroxide Solutions

This paper examines the effects of structural-textural characteristics of sulfide minerals on their leaching from polymetallic concentrates with sulfuric acid and hydrogen peroxide solutions. The polymetallic concentrate was obtained by flotation of polymetallic ore from the Rudnik deposit in Serbia. X-ray diffraction (XRD), qualitative and quantitative mineralogical, scanning electron microscopy (SEM/EDX), and chemical analyses were used to characterize the polymetallic concentrate and leach residue. The polymetallic concentrate contained chalcopyrite, galena, sphalerite, pyrrhotite, and quartz. The total content of sulfide minerals was 69.5%, and the occurrence of free sulfide mineral grains was about 60.9%. The comprehensive thermodynamic analysis was done by HSC Chemistry^® package 9.9.2.3 to determine optimal experimental leaching conditions. Chalcopyrite, sphalerite, and pyrrhotite oxidized during leaching, and dissolution occurred. The oxidized galena remains in the solid residual as insoluble anglesite. Also, elemental sulfur and unleached minerals of copper, zinc, and iron were found in the leach residues. It was found that the structural assembly of sulfide minerals in the leach residue is very favorable and that undissolved sulfide grains are primarily present in free form. Accordingly, there was no reason to reduce the leaching rate with time. The presence of elemental sulfur and anglesite formed in the leaching process and precipitated on the surface of mineral grains was confirmed by XRD, quantitative and qualitative mineralogical analysis, and SEM/EDX.