| The total amount of gold resources on the earth is relatively large,but the gold available for human use is very small.More than 99.7%of the gold resources are in the core and mantle,and humans cannot use these gold resources for a long time.With the continuous exploitation of gold resources,the easy-to-handle gold ore is gradually reduced until it is depleted.Complex gold ore,refractory gold ore and associated gold ore have become the main resources for gold production.In this paper,the quartz and kaolinite pure minerals commonly found in gold mines will be studied,and the agitation adsorption test will be carried out under different stirring time,initial gold concentration,pulp concentration and stirring intensity.It is concluded that quartz and kaolinite can be adsorbed with Au?S2O3?23-solution under different conditions.In order to verify the results of the adsorption test,infrared spectroscopy and scanning electron microscopy were performed,and the CASTEP module in Materials Studio 2016 was used to verify the quantum mechanical calculation.By infrared spectroscopy,after the adsorption of Au?S2O3?23-solution by quartz and kaolinite,the peak positions of quartz and kaolinite changed,And quartz has a new peak at 2850.42cm-1 and 2921.77cm-1,and kaolinite has a new peak at 2953.31cm-1.This indicates that quartz and kaolinite can be adsorbed with the Au?S2O3?23-solution;Scanning electron microscopy analysis showed that after the adsorption of Au?S2O3?23-solution by quartz and kaolinite,some Au elements were scattered on the surface of quartz and kaolinite,which indicated that Au was adsorbed on the surface of quartz and kaolinite.Both infrared and scanning electron microscopy indicate that both quartz and kaolinite can be physically and chemically adsorbed with Au?S2O3?23-solution.In order to further explain the adsorption mechanism,quantum mechanical calculations were carried out.Through the convergence test of the convergence functional,the truncation energy and the k-point point,the optimal calculation parameters are obtained.That is,the convergence functional of quartz is GGA-PBESOL,k point is 3×3×4,and the truncation energy is 440 eV;the convergence functional of kaolinite is GGA-PBESOL,k-point is3×2×2,and truncation energy is 500 eV.The error between the optimized crystal structure and the actual crystal structure is minimized,thereby improving the accuracy of subsequent calculations.The band structure,density of states and Mulliken population analysis of the optimized crystal structure were analyzed,and the electronic structures of quartz and kaolinite were analyzed,consider the surface energy and consider the subsequent calculations.The optimal surface layer of quartz?101?surface is obtained:atomic layer thickness 12.654?,vacuum layer thickness 16?;the best surface layer of kaolinite?001?surface is obtained:atomic layer thickness 26.532?,vacuum layer thickness 16?.The interaction model of Au?S2O3?23-with minerals was constructed,and the mechanism of action of Au?S2O3?23-with minerals was analyzed by adsorption energy,charge population analysis and bond population analysis.The results show that the Au?S2O3?23-ion can naturally adsorb on the quartz surface and kaolinite,the adsorption energies of Au?S2O3?23-ions on the surface of quartz?101?and kaolinite?001?were-386.70 kJ/mol and-438.01 kJ/mol,respectively.The distance between the Au?S2O3?23-ion and the quartz?101?surface is 1.628?for S2-O36 and 1.622?for S3-O44,and the distance O-H from the surface of kaolinite?001?is 1.615?.Through the Mulliken charge population analysis and the bond population analysis,the Au?S2O3?23-ion can be bonded on the surface of quartz?101?and kaolinite?001?,and the bonding effect is stronger.Through the combination of experimental research,infrared spectroscopy,scanning electron microscopy and quantum mechanical calculation,quartz and kaolinite can be adsorbed by Au?S2O3?23-solution.It is indicated that some gold is adsorbed by silicate minerals such as quartz and kaolinite when thiosulfate leaching gold,which affects the recovery rate of gold. |
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