Abstract: A large of leaching residue was left unprocessed after it was produced from Hulunbeier Chihong Mining Co., Ltd. using the oxygen-pressure acid leaching process, and it contains 44.33% sulfur and 192 g/t silver, in which 75.24% sulfur exists in the form of elemental sulfur and the silver is mainly distributed in angle site and plumbojaro site with ultra-fine particle size. As a result, the residue is proposed as a valuable-secondary resource. Effective separation and enrichment of sulfur and sliver-bearing minerals prior to metallurgy is commonly required for improving the extraction efficiency of values in the residue, due to the technological and economic constraints of direct metallurgy. In this work, according to the properties of the leaching residue and sulfur flotation process used in practice, the sulfur-silver flotation separation tests were performed. At the optimized operation conditions, a concentrate with grades of 86.24% sulfur and 67 g/t silver at recoveries of 93.35% sulfur and 14.93% sliver was obtained via the bench-scale circuit flotation test. Correspondingly, an industrial-scale test achieved for the effective separation of sulfur and silver-bearing minerals in the residue. It produced a concentrate assaying 81.52% sulfur and 75 g/t silver with 91.71% sulfur and 17.37% silver recoveries. The tailing assays 9.02% sulfur, 436.63 g/t silver and 5.74% lead. The industrial index has been significantly improved compared with the previous production.