| Zinc oxide ore is an important component of zinc ore resources,and the sulfidization-amine flotation method is currently the most studied method for recovering zinc oxide ore in laboratory research.However,the sulfidization-amine flotation method is sensitive to the slurry and it is difficult to eliminate the amine foam,thus this method has not yet been industrially applied on a large scale so far.Therefore,the flotation recovery of low-grade and difficult-to-process zinc oxide ores remains a major challenge in the mineral processing industry.In the flotation practice,an appropriate combination of multiple collectors can significantly improve the mineral flotation performance.Currently,the reaction mechanism of mixed collector on minerals is limited to the synergistic effect and co-adsorption that are related to the interface adsorption properties,as well as the changes in the adsorption reaction free energy of single-component collector calculated by quantum chemical simulation.However,flotation is a complex physicochemical process,and the use of a mixed collector can make the flotation system even more complex.Therefore,the scientific essence of synergistic adsorption with mixed collector has not been fully understood.Here,this dissertation focused on the thermodynamic entropy change of the adsorption of multi-component collectors on the sulfidized surface of zinc oxide ore and carried out in-depth and systematical research on the surface adsorption characteristics and flotation behavior of zinc oxide ore following the use of multi-component collectors in the sulfidization system theoretically and experimentally.All the findings provided important theoretical guidance for deeply understanding the interaction mechanism between mixed collector and minerals,which also can help to improve the flotation indexes after using mixed collector.This work used smithsonite as the research object and systematically analyzed the sulfidization behavior of smithsonite and the adsorption behavior of multi-component collectors by surface adsorption tests.By using the high-entropy flotation theory,the entropy change of different component collectors adsorbed on the surface of smithsonite,and the Gibbs free energy change after the adsorption of different component collectors were calculated,providing a theoretical basis for the subsequent high-entropy flotation recovery of smithsonite.Through using research methods such as micro-flotation tests,zeta potential determinations,solution surface tension determinations,Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),contact angle tests,DFT calculations,molecular dynamics simulation calculations,and flotation verification test of Lanping zinc oxide ores,the sulfidization mechanism of smithsonite,the flotation behavior of smithsonite and zinc oxide ores after adsorption of multi-component collectors,and the adsorption characteristics of multi-component collectors are thoroughly discussed.It is proven that the use of multi-component collectors can increase the entropy of the zinc oxide ore surface,thereby promoting the adsorption reaction and forming a stable adsorption layer on the sulfidized surface of smithsonite.Firstly,based on the theory of thermodynamic state functions,the calculation formula for the surface collection entropy after the adsorption equilibrium of collectors on the mineral is derived as (?).Taking the sulfidized surface of smithsonite as the adsorption site,and dodecylamine,pentyl xanthate,butyl xanthate,ethyl dithiocarbamate,and octyl hydroximic acid as the components of the multi-component collectors,the adsorption amounts of different component collectors on the sulfidized surface of smithsonite were measured,and the collection entropy after the adsorption of collectors on the mineral surface was calculated.The calculation results showed that as the number of components of collectors increased,the collection entropy of the mineral surface also significantly increased,while the Gibbs free energy of the adsorption reaction decreased significantly,the adsorption reaction of the multi-component collectors on the mineral surface was more sufficient,and the adsorption products were more stable.The entropy change of the solid-liquid system in the flotation of smithsonite was influenced by the concentrations of sodium sulfide of collectors,as well as the different combinations of collectors.The results of micro-flotation tests for smithsonite showed that the addition of sodium sulfide in the dodecylamine system significantly improved the flotation recovery of smithsonite.By increasing the number of components of collectors,the flotation recovery of smithsonite was significantly improved.The quaternary collector system of dodecylamine-amyl xanthate-dibutyl dithiophosphate-octyl hydroximic acid achieved a flotation recovery of over 95%for smithsonite.These experimental results all indicated that the efficient flotation of zinc oxide ore was an inevitable result of the increased entropy in the solid-liquid system of quaternary collectors.In order to deeply study and characterize the thermodynamic equilibrium state of smithsonite surface sulfide and multi-component collector adsorption,understand and analyze the adsorption mechanism of the multi-component collector on the mineral surface,a variety of advanced test methods were used to detect the thermodynamic equilibrium state of multi-component collector adsorption on sulfidized smithsonite surface.The results show that:The adsorption of dodecylamine on the sulfidized surface of smithsonite increased the surface potential.However,the addition of pentyl xanthate,butyl xanthate,ethyl dithiocarbamate,and octyl hydroximic acid as multi-component collectors reduced the surface potential of smithsonite.Multi-component collectors reduced the surface tension of the solution,which favored the adsorption of collectors on the mineral surface.After the adsorption of multi-component collectors,the absorption peaks of methyl and methylene stretching vibrations on the surface of smithsonite increased,and the peak positions shifted,indicating that multi-component collectors mainly existed in the form of chemical adsorption on the surface of smithsonite.With the increase in the number of components of collectors,the contents of C 1s,N 1s,and S 2p on the mineral surface increased,indicating that more collectors were adsorbed.After the adsorption of multi-component collectors,the contact angle on the surface of smithsonite became larger,indicating a stronger hydrophobicity.At the same time,the molecular dynamics simulation of the multi-component collector system adsorption on the smithsonite(101)crystal surface was carried out.The simulation results showed that the multi-component collector had co-adsorption on the smithsonite surface and the equilibrium configuration of the multi-component collector after co-adsorption was simulated.With the increase in the number of collector components,the relative adsorption concentration of the collector on the smithsonite surface increased,and the relative concentration of water molecules in the surface hydration film continued to decrease,resulting in a significant increase in hydrophobicity.The high-entropy flotation theory of zinc oxide ore was applied to treat low-grade and difficult-to-process zinc oxide ores from Lanping.Sodium carbonate and sodium sulfide were used as the pH adjuster and sulfidizer for lead flotation,respectively,while sodium sulfide was used as the sulfidizer for zinc flotation.KG-248 and water glass were used as the depressants,and dodecylamine,pentyl xanthate,ethyl dithiocarbamate,and octyl hydroximic acid were used as the multi-component collectors.The lead flotation process involved two rougher stages and one cleaner stage,while the zinc flotation process involved one rougher stage,one cleaner stage,and one scavenger stage.The lead middling,zinc middling,and zinc scavenger concentrate were combined for further zinc cleaning.Under the condition that the zinc grade of raw ore is 6.97%,the ideal flotation index of zinc concentrate with a zinc grade of 25.14%and zinc recovery of 87.96%is finally obtained.The use of multi-component collectors significantly reduced the foam stability of amines and greatly reduced the amount of flotation foam,thereby eliminating the overflowing.This created favorable conditions for the industrial application of this technology,especially in cases where a large amount of slurry is present.In summary,after applying the high-entropy flotation theory of zinc oxide ore,the components of collectors increased,the efficiency of collector adsorption on the sulfidized surface of zinc oxide ore also increased,which improved the stability of collector adsorption layer,and promoted the efficient flotation recovery of zinc oxide ore. |
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