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Ore from the existing minerals deposits trends towards being more complicated and lower grade.Fengshan copper mine is a skarn type of copper deposit,With exception of copper rich in ore,the associated molybdenum,gold,silver and sulfur etc,can be recovered comprehensively.The dominant metallic minerals in the ore are pyrite, yellow pyrite,peacock copper,siderites,grayantimony,indigo copper and molybdenum glance etc.Gold and silver minerals are native gold, gold-silver minerals,native silver and telluric gold-silver minerals etc. The dissemination of gold-silver minerals is more complicated,which are characterized by both unevenly stellar distribution of gold-silver minerals in gangue ore and close association of gold-silver minerals with yellow pyrite and peacock copper.The circuit of rougher flotation—scavenging—recleaner flotation and rough concentrate regrinding to separately process the separation of copper and sulfur is used on site.Under conditions that grades of feed ore are 0.9%Cu,0.2-0.4g/t Au and 7-10g/t Ag,it can result in copper concentrates assayed 20.7%Cu,5.16g/tAu and 162.27g/tAg and sulfur concentrates assayed 36.5%,the copper recovery of 85.26%,gold recovery of 54%and silver recovery of 57%are obtained.Based on the existing technical index of selective separation of ore,the author makes an attempt to further increase the recovery of gold and silver.On the basis of the analysis of minerals composition,mineralogical phase,dissemination characteristics of metallic minerals and size distribution the ore,bulk flotation and selective flotation etc,are used respectively.The effect of dose of lime,conditioning agent and collector, and grinding fineness on flotation index was investigated.It has been shown that adjusting the related parameters of processing circuit the recovery of copper,gold and silver can be up to 85%-88%,about75%and 72%or so respectively.The recovery of copper,gold,silver and sulfur of composite ore samples（A）can be up to 93.58%,82.09%,76.81%and 69.41%respectively,for composite ore samples（B）,the recovery of copper,gold and silver is 92.72%～94.64%,63.02%and 65.76%～67.34% respectively under condition of ground fineness of 70%（-0.074mm）.Based on electrochemical measurement,the interaction mechanism between xanthate and pyrite,chalcopyrite was studied,the results show the formation of dixanthogen is the dominant factor but could not be the sole hydrophobic entity responsible for the flotation of pyrite and chalcopyrite.Corrosive electrochemistry results suggest that lime depresses sulfide minerals’ dissolver and the reaction between xanthate and pyrite is depressed resulting minerals can not be flotation.The electron structure of FeS2（110）surface was computed by way of DFT and the process of electron transfer in sulfide flotation was simulated through ab-initio calculation and molecular dynamic simulation.The results show that electrons transfer from xanthate to the pyrites’ surface for intrinsic pyrite and xanthate adsorption on its surface is occurred.For sulfur vacancy pyrite,conducted band and valence band overlap,the surface of minerals have high electron and vacancy density,so the adsorption of xanthate on the sulfur vacancy pyrite is higher than that of intrinsic pyrite.For Fe vacancy pyrite,xanthate do not occur adsorption on its surface due to the high Fermi energy.Molecular dynamics simulation of the interaction between lime and pyrite indicate that both OH- and CaOH+ can adsorb on pyrite surface,so pyrite was depressant with lime as regulator.
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