| Sulfide minerals and grinding media have different electrostatic potentials,and their contact with each other will produce electron transfer leading to surface charge redistribution,affecting the oxidation of minerals and flotation recovery.A large number of experimental results show that the results of single mineral flotation system have a big difference with the results of mixed ore flotation system,and single mineral flotation results could not guide the actual ore flotation.The establishment of theory for multi-mineral system flotation needs.In this paper,the quantum chemical method based on density functional theory and the electrochemical test were used to study the effect of galvanic interaction on the surface structure,surface activity,grinding and flotation.The main findings are as follows:(1)Electrochemical research for the effect of galvanic interaction on the surface oxidation and xanthate electrochemical adsorption capacity of chalcopyrite,galena and pyrite by using powder microelectrodeFor the galena-pyrite system,at pH 9.18,the oxidation of the mineral surface is inhibited by the galvanic effect between galena and pyrite;at pH 6.86,the oxidation of the mixed microelectrode is weaker than galena,and is stronger than pyrite.In addition,when the pH value is 9.18,the galvanic effect between galena and pyrite promotes the adsorption of xanthate on the mineral surface.For the chalcopyrite-pyrite system,when the pH value is 9.18,the oxidation degree of the mixed microelectrode is weaker than that of the pyrite,and is stronger than that of the chalcopyrite.When the pH value is 6.86,the galvanic effect between chalcopyrite and pyrite may promote oxidation of the mineral surface.In addition,when the pH is 9.18 or 6.86,the galvanic effect between chalcopyrite and pyrite may inhibit the adsorption of xanthate on the mineral surface.For the chalcopyrite-galena system,when the pH value is 6.86 or 9.18,the oxidation degree of galena is strongest,followed by the mixed microelectrode,and that of chalcopyrite is the weakest.In addition,at pH 9.18,the galvanic effect between chalcopyrite and galena may slightly inhibit the adsorption of xanthate on the mineral surface.When the pH value is 6.86,the galvanic effect between chalcopyrite and galena may have little effect on the adsorption of xanthate on the mineral surface.(2)The effect of galvanic interaction between pyrite and galena on the electronic structure,properties and adsorption capacity of galena(100)The slab-slab model can well study the atomic activity and electronic structure of the solid-solid interface,while the cluster-slab model is suitable for investigating the influence of the galvanic interaction on adsorption of reagents.The electron transfers number between pyrite and galena decreases with the contact distance increases.The galvanic effect can still occur even when the contact distance is greater than the sum of two atoms radius(?3 A).When contact distance is 10 A there is no galvanic interaction between galena and pyrite.For the galena surface,the Pb 6s state lost electrons resulting in an increase in the positive changes of Pb atoms.For the pyrite surface,the Fe 4p state obtains a large amount of electrons,resulting in a reduction in the number of positive charges of Fe atoms.The galvanic interaction between pyrite and galena promotes the adsorption of oxygen and xanthate molecules on galena(100)surface,and the stronger the galvanic interaction,the stronger the adsorption of oxygen and xanthate molecules.(3)Effects of galvanic interaction between chalcopyrite and galena on the adsorption of oxygen and xanthate molecules adsorbed on the chalcopyrite(001)surfaceOxygen molecules can be strongly adsorbed on the Fe-S sites of the chalcopyrite(001)surface and dissociated.With the galena galvanic effect,the bond length between oxygen molecules and chalcopyrite(001)surface grows longer,especially at this time,oxygen molecules cannot dissociate adsorption on the chalcopyrite surface,resulting in a significant increase in adsorption energies.Moreover,with the galena galvanic effect,the bonding effect of O-Fe bond DOS is inhibited,while the bonding effect of O-S bond DOS is enhanced.The galvanic interaction between chalcopyrite and galena may inhibit the adsorption of oxygen molecules on the surface of chalcopyrite(001).The xanthate molecules can be strongly adsorbed on the Cu-Fe site of chalcopyrite(001)surface.After the galvanic contacting with galena,the bond length between the S atom of the xanthate and the Cu atom on the surface of the chalcopyrite(001)becomes shorter,while the bond length between the S atom of the xanthate and the Fe atom on the chalcopyrite surface becomes longer,and the adsorption energy value of xanthate adsorbed on the chalcopyrite surface become larger.Moreover,the galvanic interaction makes the bonding effect of S-Cu bond and S-Fe bond DOS weakened.The galvanic interaction between chalcopyrite and galena may inhibit the adsorption of xanthate molecules on the chalcopyrite(001)surface.(4)Effects of galvanic interaction between chalcopyrite and pyrite on the adsorption of oxygen and xanthate molecules adsorbed on the chalcopyrite(001)surfaceAfter the galvanic contacting with pyrite,the adsorption energy-value of oxygen molecules adsorbed on chalcopyrite(001)surface at Fe-S site increases,and the bond length becomes longer and the dissociation degree of oxygen molecules becomes smaller.In the meantime,the bonding effect of O-S bond DOS is weakened,and the bonding effect of O-Fe bond is not changed.The galvanic effect of chalcopyrite and pyrite may inhibit the adsorption of oxygen molecules on the chalcopyrite(001)surface.After the galvanic contacting with pyrite,the adsorption energy value of xanthate molecules adsorbed on chalcopyrite(001)surface increases and the bond length becomes longer.Moreover,the bonding effect of S-Cu bond DOS is slightly enhanced,and the bonding effect of S-Fe bond DOS is not changed.The galvanic effect of chalcopyrite and pyrite may inhibit the adsorption of xanthate molecules on the chalcopyrite(001)surface.(5)Effects of galvanic interaction between grinding medium and galena on the adsorption of oxygen and xanthate molecules adsorbed on the galena(100)surfaceFor low carbon steel,medium carbon steel,high carbon steel grinding media and galena system,the galvanic interaction between medium carbon steel(carbon content of 0.3%)and galena is strongest,and at the moment the adsorption of xanthate and oxygen molecule on the galena surface is also the strongest.While the galvanic interaction between low carbon steel(carbon content of 0.1%)and galena is weakest.For chromium-containing,cerium-containing,lanthanum-containing,yttrium-containing and manganese-containing grinding media and galena system,chromium,cerium,manganese elements slightly weaken the galvanic effect between grinding medium and galena surface,and the galvanic interaction between cerium-containing grinding medium and galena is weakest.Lanthanum and yttrium elements slightly enhanced the galvanic interaction between grinding medium and galena surface,which the galvanic interaction between contains yttrium grinding media and galena is strongest.When using La-grinding media,the adsorption of oxygen and xanthate molecules on galena surface is the strongest,and the use of Mn-containing grinding media may be detrimental to the adsorption of oxygen on galena surface.The use of Y-containing grinding media relatively detrimental to xanthate molecules adsorbed on galena surface. |
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