Abstract: Lead， zinc， silver and carbon contents in a lead-zinc ore of Gansu are 0.90%， 3.14%， 25.63 g/t and 6.30%， respectively. The ore belongs to high carbon lead-zinc ore， the main metal minerals in the ore are galena， sphalerite and pyrite， gangue minerals are mainly quartz， and the main carbon-bearing minerals are calcite. Galena is mainly xenomorphic granular and unequal grain embedding， some of the finer grains are scattered in the ores， while the larger grains are closely associated with sphalerite and silver-bearing minerals， sphalerite is mainly xenomorphic granular， basically has no silver， a small amount in form of fine-grained star scattered in the ore， most of which are coarse-grained， in the form of vein-like， banded， veinlet-like aggregates. The presence of carbonaceous minerals in ore can lead to difficult separation of lead and zinc. In order to solve the problem of mutual inclusion and separate of lead-zinc ore， experiment research on mineral processing had been conducted. The results showed that when the grinding fineness is -200 mesh accounts 65%， the low alkali process of one roughing three cleaning two scavenging was adopted to preferentially concentrate lead， and one roughing two cleaning two scavenging was adopted to concentrate zinc， lead concentrate with 51.45% lead， 1 098.00 g/t silver， 4.89% zinc， lead recovery of 85.26%， silver recovery of 64.17%， and zinc concentrate with 53.38% zinc， 84.87 g/t silver， zinc recovery of 91.14%， and silver recovery of 17.73% could be obtained.

Key words: High carbon, Lead and zinc separation, Low alkalinity, Flotation