Research On The Efficient Flotation Separation Of Sulfide Minerals In Gold Concentrate Cyanide Tailings

Cyanidation tailings leached from gold concentrate(hereafter referred to as cyanide tailings)are often associated with valuable minerals such as chalcopyrite,galena,pyrite and sphalerite.Due to the surface of sulfide minerals in the cyanide tailings covered by CN-,thus the minerals can not get flotation separation easily.In this study,on account of difficult problem to flotation sulfide minerals after CN-adsorption,the characteristics of CN-adsorbing on the surface of sulfide minerals were studied,and then the flotation separationefficiently of sulfide mineral in the cyanide tailings from Shandong Zhongkuang Group CO.LTD was researched,which conducted to lay the foundation for theoretical and experimental research on the flotation separation of sulfide mineral in the cyanide tailings.In the study,the adsorption characteristics of sodium cyanide(NaCN)on the surface of chalcopyrite,galena,sphalerite and pyrite was investigated at first,and the adding amount of NaCN was similar to CN-content in the cyanide tailings flotation.Effection of the adsorption time,pulp pH value of solution and concentration of minerals on the cyanide adsorption process were mainly studied.The purpose of this study is to analyze the mechanism of CN-adsorption on different sulfide minerals surface and its inhibition in subsequent flotation during the cyanide leaching.The results were shown that the adsorption of sulfide minerals surface to CN-was a fast adsorption process.The CN-adsorption rate of chalcopyrite,galena,pyrite and sphalerite was 71.09%,63.77%,84.13%and 90.60%respectively in the experimental conditions of adsorption time 1 min,NaCN concentration 100.0 mg-L-1,mineral dosage 2.0 g,pH value 9.5,adsorption temperature 25? and agitation speed 1200 r·min-1.The results also indicate that the absorption interaction between CN-and the surface of chalcopyrite,galena,pyrite and sphalerite could be described by the Langmuir adsorption isotherm model,which means a monolayer chemical adsorption.In the flotation system using butyl xanthate(BX)and diethyldithiocarbamate(DEDTC)as the collectors,single mineral flotation tests were performed to research the flotation separation rule of sulfide minerals in cyanide tailings using chalcopyrite,galena,pyrite and sphalerite after Cyanide Treatment(hereinafter referred to as the CT-chalcopyrite,CT-galena,CT-pyrite,CT-sphalerite)as the samples.The results indicated that under the conditions that at flotation pH value 6.0 and the concentration of BX 40 mg·L-1,the recovery of CT-chalcopyrite was 74.42%;and while the flotation pH value was 9.5 and the dosage of DEDTC was 30 mg·L-1,the recovery of CT-galena was 84.48%.However,when using BX and DEDTC as the collectors,the flotation effect of CT-pyrite and CT-sphalerite was not ideal.The adsorption characteristics of CN-on the sulfide minerals surface and the interaction mechanisms of BX and DEDTC on CT-sulfide minerals were discussed,which further based on the solution chemical analysis,measurements of contact angle and Zeta potential.The results of solution chemical analysis showed that the inhibitory effect of cyanide ion on the surface of chalcopyrite,pyrite and sphalite was relatively strong,while galena was the weakest.BX and DEDTC were competitive with CN-on the surface of CT-sulphide mineral in the form of chemical bond adsorption.When the adsorption effect of collector was stronger than CN-,the flotation recovery of sulfide minerals under CN-inhibition could be realized.The results of contact angles measurements showed that NaCN reduced contact angles of chalcopyrite,galena,pyrite and sphalerite surfaces,and reduced the hydrophilicity of the mineral surface.The subsequently added BX and DEDTC both improved the contact angles of CT-sulfide minerals and increased the floatability of the minerals.Seen from the results of Zeta potential analysis measurements,when the pH value was 9.5,there existed no electrostatic adsorption between CN-and chalcopyrite,galena,pyrite and sphalerite surfaces,and the interaction of BX or DEDTC on the CT-chalcopyrite,CT-galena,CT-pyrite and CT-sphalerite surface were no electrostatic adsorption.And there might existed electrostatic adsorption between CN-and the surface of chalcopyrite,DEDTC and the surface of CT-chalcopyrite in the flotation process of CT-chalcopyrite(pH 6.0).The Dmol3 module in Materials Studio(MS)8.0 software was used to build the models of CN-,BX and DEDTC.And the CASTEP module was used to build the crystal cell of chalcopyrite,galena,pyrite and sphalerite.The calculated XRD data were compared with the experimental ones to verify the validity of the computed crystal cells.The adsorption models of CN-,BX and DEDTC on the sulfide mineral surfaces were builded using the CASTEP module and the adsorption energies were calculated.The Mulliken charges and Mulliken population,the energy differences of the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecule orbital(LUMO),were analysed to investigate the properties of the sulfide mineral surfaces and the adsorption mechanism of the reagents on mineral surfaces.MS calculation results showed that CN-adsorbing on the mineral surface was bonding in the form of C atoms with atomic metal,BX and DEDTC ions adsorbing on the chalcopyrite and pyrite surface were formed by single bond S(S1)and double bond S(S2),which fromed delocalization ? bond,and covalency were strong.C atoms of CN-and Pb atoms of galena were adsorbed to be ionic bonds,and the bonding were weak.More electron transfer on the surface of galena by absorbing DEDTC,and more electron transfer on the surface of chalcopyrite by absorbing BX.The HOMO and LUMO energy level differences between BX,DEDTC and CN-on the surface of pyrite and sphalerite were similar,which supposed the adsorption intensity fairly,and could not significantly reduce the adsorption inhibition of CN-on pyrite and sphalerite surface.Finally,flotation condition test,open circuit test and close circuit test of real cyanide tailings were conducted using the cyanide tailings provided by Shandong Zhongkuang Group CO.LTD.Based on the process mineralogy of cyanide tailings and demand of the actual production,the copper and lead were the valuable wanted objects.According to the difference of the inhibiting effect of CN-on copper and lead minerals,the priority flotation process for the recovery of lead and then the recovery of copper was carried out.Eventually,the grade of lead in lead concentrate was 21.07%and recovery was 61.21%,while the grade of copper in the copper concentrate was 10.75%and recovery was 62.69%.The research findings in this study have guiding significance to flotation separation and comprehensive utilization of sulfide minerals in the gold concentrate cyaniding tailings.