Mineralogical characterization of a polymetallic sulfide ore to improve silver recovery

Abstract

Based on the mineralogical characterization for the polymetallic sulfide ore, the way to improve silver recovery was studied. The results showed that silver was the most valuable metal whose grade was 448.82 g/t Ag, while 0.118% Cu, 1.65% Pb and 1.06% Zn may be comprehensively utilizated. The main silver-bearing minerals were argent and aregentite which accounted for 87.18% of total silver. Argentite and other metal minerals were distributed in the gangue minerals in complex forms. Argentite grains of 33.76% minus 50 μm indicated that a fine grinding scheme was necessary to enhance the degree of dissociation, and meanwhile selective grinding must be considered to prevent a complete grinding of coarse grains. The optimum regrinding fineness in the Cu flotation was determined as 73% minus 37 μm, while grains of 68.5% minus 74 μm in one-stage grinding remained unchanged as much as possible. Consequently, silver recovery increased to 2.68%, as well as the content of Pb simultaneously decreased from 7.26% to 2.68% in the Cu concentrate. From the lead pyrometallurgical point of view, recovering larger amounts of silver and lead at the expense of decreasing the grade of lead to a suitable level is not only economically viable for the plant, but also convenient for subsequent processing. Silver and lead recovery increased to 13.18% and 12.58%, respectively, while the Pb grade decreased from 53.1% to 46.12% for the Pb concentrate.