Abstract: In order to efficiently develop and utilize a low-grade silver-bearing lead-zinc mine in Northeast China,and solve the problems of high lead-zinc concentration,low recovery rate of associated metal silver,and difficulty in direct reuse of wastewater in the on-site separation process,a new low alkaline flotation process was studied on the basis of process mineralogy research,and the appropriate beneficiation flowsheet and reagent system were determined through the lead -zinc flotation condition tests. The results showed that for the raw ore containing lead of 1. 33%,zinc of 2. 51%,and silver of 19. 5 g / t,the leadzinc preferential flotation process was adopted. Under the condition that the grinding fineness of - 0. 074 mm accounted for 75. 42%,sodium carbonate was used as a pH regulator,zinc sulfate and sodium sulfite were used as inhibitors,and aniline+ammonium butyrate black powder was used as a collector. After one roughing,three cleaning and two scavenging lead flotation,the lead concentrate containing lead of 57. 52%,zinc of 4. 84% and silver of 585. 40 g / t were obtained with lead recovery rate of 85. 38% through clear water closed-circuit test,while the recovery of silver in lead concentrate is 57. 63%. The lead tailings were treated with copper sulfate as an activator,lime as an inhibitor,and aniline+butylamine black powder as a collector. The zinc concentrate containing zinc of 51. 85%,lead of 1. 38%,silver of 52. 20 g / t,zinc recovery rate of 90. 71%,and silver recovery rate of 11. 65% was obtained by one roughing,two cleaning and two scavenging zinc flotation. The indexes of lead and zinc using return water were similar to those in clear water. The application of aniline+butylammonium black powder as the lead-zinc flotation collector enabled conventional inhibitors to replace lime or reduce the dosage of lime,thereby achieving the low alkaline lead-zinc separation and enabling the silver enrichment in lead concentrate,and the return water can be reapplied to the production process.

Key words: lead-zinc sulfide ores,low alkaline flotation,preferential flotation,aerofloat collector,combined inhibitor,return water recycling