Low−alkali Flotation Technology of High−Sulfur Complex Lead−Zinc Ore in Hu’nan

A lead-zinc sulfide ore from Hunan features high sulfur content and finely disseminated mineral grains, assaying 1.36% Pb, 6.48% Zn and 32.98% S. Its primary metallic minerals are galena, sphalerite and pyrite. Based on the process mineralogical analysis and conditional tests, the process flow of “priority lead flotation−priority zinc flotation−regrinding and reselection of zinc middlings− sulfur flotation” was adopted for lead−zinc sulfur separation. In the process of giving priority to lead selection, the grinding fineness of −0.074 mm accounted for 92.86%, zinc sulfate and sodium sulfite were used as zinc inhibitors, and HB−01 was used as the collector. During the zinc selection process, DX−03 is a sulfur inhibitor, copper sulfate is an activator, and HB−02 is a collector. The regrinding fineness of zinc middlings is 0.037 mm, accounting for 90.03%, and the CYM−8 was used as collector in the flotation of sulphur. The closed−circuit experiment finally obtained lead concentrate with a lead grade of 32.89% and a recovery rate of 75.77%, zinc concentrate with a zinc grade of 51.34% and a recovery rate of 77.14%, and sulfur concentrate with a sulfur grade of 48.59% and a recovery rate of 82.61%. The zinc middlings could be re−ground and separated to obtain a zinc grade of 38.98% and a recovery rate of 15.54% in zinc concentrate. Compared with the existing industrial high−lime high−alkali full priority flotation flowsheet and corresponding reagent regime, the proposed process achieved a significant improvement in the separation performance of Pb, Zn and S, realizing lime−free, high−efficiency and clean beneficiation of the target lead−zinc ore. This work provides a valuable technical benchmark and reference for the high−efficiency beneficiation of high−sulfur micro−fine grained complex lead−zinc ores under low−alkali conditions.