| The separation of Cu-Zn polymetallic sulfide by flotation has been a difficult and well-researched topic in the field of mineral processing.One of the important reasons why it is difficult to separate Cu and Zn is the presence of a large amount of copper ions in the pulp,which results in the unavoidable activation of sphalerite.The key to solving this difficulty is the development of a high selectivity depressor for sphalerite.In this investigation,a new method for the separation of Cu-Zn polymetallic sulphide is proposed:“inorganic inhibitor+organic inhibitor with low molecular weight”is used as an inhibitor for the separation of Cu-Zn polymetallic sulphide.In this paper,chalcopyrite and sphalerite are chosen as the research object.Firstly,the inhibition performace of organic inhibitor sodium dimethyldithiocarbamate?SDD?and many traditional inhibitors on mineral was compared by single mineral flotation test and the optimal combination inhibitor ZnSO4+SDD is screened out by the combination ratio test.On this basis,the inhibition mechanism of SDD and ZnSO4+SDD was studied.The flotation results showed that the SDD is an effective depressant of the copper-zinc separation.Sphalerite can be depressed effectively in the presence of SDD(the optimum conditions were:pH=10 and SDD dosage of 4.0×10-5mol/L,)while chalcopyrite is not depressed.In addition,it was found that SDD has the characteristics of small dosage and high sensitivity.The inhibition ability of SDD to Cu-activated sphalerite is similar to that of Na2S,but it is superior to ZnSO4 and Na2SO3.On this basis,the ZnSO4+SDD was selected from various combination depressors by single mineral flotation tests,and the optimal conditions was determined as:[ZnSO4+SDD]=1×10-4mol/L+3×10-5mol/L and pH=10.When the ZnSO4+SDD was used to treat Cu-Zn?1:1?mixed sulfide ores,the dosage of the reagents were slightly higher than the half of the amount of the single mineral flotation reagent.Under the optimal conditions of ZnSO4=7.5×10-5mol/L,SDD=2.5×10-5mol/L,pH=10 and BX=1×10-5mol/L,a copper concentrate assaying 30.21%Cu with 86.79%recovery was achieved from the Cu-Zn sulfide flotation system,and this concentrate had a very low Zn grade of 4.20%with 5.48%recovery.It was found that the inhibition performance of ZnSO4+SDD on mixed Cu-Zn sulphide ore is better than that of single using SDD.The Zeta potential test showed that the inhibitions of SDD and ZnSO4+SDD could significantly reduce the adsorption amount of BX on the Cu-activated sphalerite surface in the alkaline solutions?especially pH=9-12?.However,the inhibition of SDD and ZnSO4+SDD for chalcopyrite was smaller in the pH=2-12,and the SDD with BX can be co-adsorbed on the chalcopytite surface.It was further found from the microelectrochemical test?LEIS?that the copper ions can significantly reduce the microzone impedance on the sphalerite surface and improve the activity of the sphalerite surface.In addition,it was found that the microzone impedance?average impedance:1.31×105??on the sphalerite surface was significantly lower than that?average impedance:1.05×105??on the chalcopyrite surface.SDD and ZnSO4+SDD can prevent BX adsorbing on the Cu-activated sphalerite surface by a competitive adsorption method.but the SDD and ZnSO4+SDD with BX are co-adsorbed on chalcopytite surface.Frontier orbital energy calculation results showed that the S 3p orbital of reagents?SDD and BX?interacts with Zn 3d orbital of ZnS?110?surface and Cu 3d orbital on Cu-activated ZnS?110?surface.The interaction ability of SDD with sphalerite or Cu-activated sphalerite is stronger than that of BX.From the adsorption energy calculation,it showed that the SDD is more stable than the BX on the Zn site of the ZnS?110?surface and the Cu site on the copper-activated ZnS?110?surface regardless of the presence or absence of water molecules in the simulation.It was found that the water molecules would enhance the nonlocality of the S 3p in SDD and BX on ZnS?110?surface in the presence of water molecules,the splitting of the peaks and the decrease of the overlap area of the orbits,which weakens the interaction ability between the sulfur atoms of the reagent and the zinc atoms.It was found that water molecules would enhance the nonlocality of the Cu 3d on Cu-catived ZnS?110?surface in the presence of water molecules,the splitting of the peaks and the decrease of the overlap area of the orbits,which weakens the interaction ability between the sulfur atoms of the reagent and the zinc atoms and the peak splitting intensity under SDD is lower than that under BX.It was revealed by SEM-EDS and Visual MINTEQ that the Zn?OH?2 of the ZnSO4 hydrolytic production adsorbes on the copper-activated sphalerite surface,which increases the hydrophilicity of mineral surface.the ZnSO4 with SDD are co-adsorbed on Cu-activated sphalerite surface,which makes that the ZnSO4+SDD has a strong inhibitory effect on copper activated sphalerite. |
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