A Study On Separating Lead And Zinc From Mixed Concentrate

Sphalerite activated by Cu2+ have high flotability is hard be depressed. So sphalerite allways be missed in lead concentrate, copper concentrate and pyrite concentrate when separating multi-metal sulphide ores that contains zinc. LanPing lead-zinc-sulfer mixed concentrate activated by cupric sulfate contains massive dose of collector and frother. So it is hard to separate sphalerite from mixed concentrate.This papper focus on the practical problem that sphalerite activated by Cu2+ makes multi-metal sulphide ores hard be separated, The effects of pH, metal ions, depressants on the floatability of galena, sphalerite and pyrite were investigated by flotation tests. At the same time, the activation mechanisms and depression mechanisms were studied by the test of contact angle, adsorption quantity and calculations of flotation solution chemistry. At last, actual ore tests were taked. Major conclusions and innovations of this thesis are obtained as follows:(1) Comparing to Pb2+ and Ca2+, better results were obtained when use Cu2+ to activate sphalerite and pyrite, conentration and pH are two of most impotant factors on process of the activation. As to galena, sphalerite and pyrite activated by Cu2+, ZnSO4 and Na2SO3 can not increase the difference of their flotability, but Na2S can depress sphalerite effectively when concentration on 2.00×10-4mol/L～2.15x10-4mol/L, but galena and pyrite still have high flotability in this condition. It is good to separate sphalerite from mixed concentrate activated by Cu2+(2) The lead-zinc-sulfer mixed concentrate activated by cupric sulfate contains massive dose of collector and frother. In this study, from the way of controling concentration of sodium sulfide, sphalerite was separated from the mixed concentrate successfully by flotation galena, pyrite and depressing sphalerite. When the grades of lead and zinc are 9.32% and 20.01% in the run of mine, the grade and recovery in the sphalerite concentrate of close circuits can be 36.04% and 89.44%.(3) The depression mechanisms were studied by the test of contact angle, adsorption quantity and calculations of flotation solution chemistry. The results show that hydrophobic xanthic acid salt that formates on the surface of sphalerite were decomposited or desorpted by HS-, then HS-adsorbed on surface of sphalerite that makes sphalerite hydrophilic. At the same time, Na2S turns down pulp potential that reduces collecting ability of xanthate.