Abstract: Aiming at the problem of the high zinc contents in the lead concentrate and high lead-zinc contents in the sulfur concentrate of a lead-zinc concentrator in the northeast Yunnan ， the experimental study on process optimization was carried out on the basis of the study on process mineralogy of the ores. The results showed that mineral species of the ores are complex， of which the granularity of galena and sphalerite are unevenly disseminated. The one-stage grinding process of "lead-sulfide mixed flotation， separation of the lead-sulfur mixed concentrate with sulfur inhibition and lead flotation， and zinc selection from the flotation tailings after sulfur-lead selection" was obtained on site. While galena， sphalerite and pyrite with fine-disseminated is not fully monomer dissociated. The study puts forward the process of "stage grinding and stage selection" for process optimization. The bulk lead-sulfur concentrate was regrinded and reselected. In the condition of regrinding fineness of -0.045 mm accounting for 70%， the lead concentrate of lead grade of 61.89% and lead recovery rate of 85.43%， and zinc concentrate of zinc grade of 49.05% and zinc recovery rate of 93.91% were obtained enventually. Compared with the indexes before optimization， the lead grade increased by 1.57% in lead concentrate and zinc contents decreased by 1.35% at the same time. The lead and zinc in the sulphur concentrate were lower， and zinc recovery rate of the zinc concentrate increased by 2.43%. At present， the site has completed the transformation of the dressing plant according to the optimized process. The vertical spiral mixing mill has been used for the two-stage grinding. The production operation is good， and the production indexes have been improved compared with the previous production.

Key words: lead-zinc mine, process optimization, stage grinding, stage selection