Study On The Mechanism Of Organic Complexing Agent Dissolution-complexation Enhanced Sulfidation On The Surface Of Hemimorphit

As the demand for zinc products rises and the zinc industry continues to grow,the reserves of zinc sulfide ore are being exhausted at an alarming rate,and the exploitation and utilization of zinc oxide ore are paid more and more attention.Hemimorphite is one of the main zinc oxide minerals,and its zinc content is up to 67.0%,second only to smithsonite.Therefore,enhancing the sulfidation efficiency of hemimorphite is crucial for the progress of zinc reserves in China.The recovery methods of hemimorphite are mainly divided into sulfide–xanthate flotation and sulfide–amination flotation.Both of these methods have their own disadvantages,so they have not been widely used in industry.The former is very sensitive to the slime,resulting in the actual production process there is a large amount of pharmaceutical consumption,and foam,long life,stability,difficult to eliminate and often run trough and other problems,seriously affect the normal production.The latter sulfidation process is more difficult,and after the sulfide ore,it also needs to add metal ions to activate,and then use high xanthate to collect it.Therefore,how to effectively strengthen the surface of hemimorphite and obtain stable"zinc–sulfur"compound surface has become the key to the success of"sulfidation–xanthate method"for zinc oxide minerals.Therefore,in view of the complex structural characteristics of hemimorphite,as well as its surface is difficult to sulfidation and low drug application rate.This paper proposes a model of"organic complexing agent dissolution on the surface of hemimorphite–complexing strengthen sulfidation".That is,based on the insoluble nature of hemimorphite,organic complexing agent CH₆N₂O₂ is used to slightly dissolve the surface of hemimorphite,so that the organic complexing agent can form stable adsorption with zinc on the surface of hemimorphite.Increase the activity of zinc atoms on the mineral surface.After adding sulfide agent,S^2-are more likely to be adsorbed on the surface of hemimorphite,and more stable"zinc–sulfur"compounds are generated on the mineral surface.At the same time,the organic complexing agent re–enters the mineral pulp solution,plays the role of complexing strengthen,and effectively realizes the strengthen sulfide on the surface of the hemimorphite,creating better conditions for the flotation of the"sulfidation–xanthate"hemimorphite.The surface organic complexation agent dissolution and complexation strengthen can effectively solve the technical problem that hemimorphite is difficult to sulfide,and has practical significance for the efficient recovery and sulfidation of zinc oxide ore resources dominated by hemimorphite.In this paper,the hemimorphite as the research object,first carried out the flotation test of strengthen sulfide hemimorphite,to determine the main factors affecting the flotation effect（CH₆N₂O₂ dosage,Na₂S·9H₂O dosage,（CH₃COO）₂Pb·3H₂O dosage,Na IX dosage）the optimal dosage.Then the morphology and properties of the hemimorphite before and after sulfidation were characterized by atomic force microscopy,scanning electron microscopy,X-ray photoelectron spectrometer,time–of–flight secondary ion mass spectrometer,Zeta potential analysis and other detection methods,and the effect of CH₆N₂O₂ as complexing agent on sulfide flotation of hemimorphite was explored.Sulfide flotation results showed that when the dosage of CH₆N₂O₂ was 8×10^-4 mol/L,the dosage of Na₂S·9H₂O was 5×10^-4 mol/L,（CH₃COO）₂Pb·3H₂O the dosage of was 1.5×10^-4 mol/L,and the dosage of Na IX was 5×10^-4 mol/L,the recovery rate of flotation after intensive sulfidation is 28.12%higher than that of direct sulfidation.AFM was used to analyze the changes of hemimorphite surface morphology and roughness after direct sulfidation and strengthen sulfidation.The results show that the presence of CH₆N₂O₂promotes the adsorption of Na₂S on the surface of the hemimorphite,which makes the sulfide effect on the surface of the hemimorphite more obvious.Through SEM–EDS analysis of semi–quantitative results of direct sulfidation and strengthen sulfidation of hemimorphite,after the addition of CH₆N₂O₂,the surface of the hemimorphite is better combined with S^2-,and more Zn S are formed on the surface,the hemimorphite surface is stimulated with a greater sulfide effect and this leads to an augmentation in the adsorption of xanthate.By analyzing the XPS of the samples under different conditions,it can be obtained that after adding CH₆N₂O₂ and Na₂S·9H₂O,more Zn S were formed on the mineral surface,which strengthen the sulfide action on the surface of hemimorphite,and created better conditions for sulfidation–xanthate flotation of hemimorphite.To F–SIMS analysis was carried out on the samples of hemimorphite after strengthen sulfidation,and the To F–SIMS results showed that CH₆N₂O₂ destroyed the surface structure of the hemimorphite.After the addition of CH₆N₂O₂,the strengthen sulfidation forms a thicker Zn S film covering the mineral surface.The complexing agent CH₆N₂O₂ enhanced the adsorption of xanthate on mineral surface.The Zeta potential results show that CH₆N₂O₂ can dissolve the mineral surface at p H 8～11,which increases the adsorption of S^2-or HS^-on the mineral surface,and makes more xanthate adsorbed on the hemimorphite surface.DFT calculation shows that:In the absence of H₂O molecules,the 3p orbital electrons of S and the 3d orbital electrons of Zn overlap in the range of–12.07 e V～0.61e V,this indicates that the 3p orbital electrons of S and the 3d orbital electrons of Zn are interacting,that is,the reaction produces Zn S species;When H₂O molecules are present,it will form a hydration film on the surface of hemimorphite,and the hydration film will hinder the adsorption of HS^–on the surface of hemimorphite（110）;The influence of NH₃ on the hydration layer is divided into two stages:The first stage is when NH₃ is added,and the distance between Zn and O5 is 2.3（?）.In the second stage,NH₃ displaces H₂O molecules,and the distance between Zn and O5 is 5.6（?）;Under the action of NH₃,the adsorption energy of HS^–on the surface of hemimorphite（110）is more negative（-5.26e V）than that without NH₃.The results show that the adsorption configuration of NH₃ and HS^–is more stable than that of HS^–.