Flotation Performance And Molecular Dynamics Simulation Of Aluminum-silica Mineral Quaternary Ammonium Salt Collectors

Aluminum industry has developed rapidly and has now become the largest alumina producer in our country.Compared with foreign bauxite,the bauxite of our conutry has the characteristics of high aluminum,high silicon,and low iron,and the aluminum-silicon is relatively low.Therefore,reasonable and effective methods are used to increase the aluminum-silicon ratio of raw materials to meet the Bayer process.Conditions have become a problem that needs to be solved urgently.In this paper,dodecylamine,quaternary ammonium salts and their mixtures are used as collectors to study the flotation test of diaspore and gangue minerals,mixed ore and actual minerals.Adsorption capacity determination,Zeta potential determination,infrared spectroscopy and molecular dynamics simulation were used to study the adsorption mechanism of flotation reagents on mineral surfaces.The single-agent collector is used to conduct a single-mineral flotation test study.The results show that the floatability of kaolinite is stronger than that of diaspore,and when the flotation environment is at a lower p H,two minerals have a greater difference in flotation recovery rate.Compared with the collector DDA,three quaternary ammonium salt collectors show a difference in the recovery rate of the two minerals in a wider p H range.Among the three quaternary ammonium salt collectors DTAB,TTAB,and CTAB,when the p H value of the CTAB collector is 2 and 4,the difference in the recovery rate of the two minerals reached to about 61.9% and 51.7%,and with the p H value continuing to increase,there is a big difference in recovery rate.Therefore,CTAB can separate diaspore and kaolinite in the wide p H range.As the concentration of CTAB agent increases,the recovery rate of kaolinite increases,but the recovery rate of diaspore increases more rapidly.Therefore,with the great concentration of CTAB,the reverse flotation separation of the two minerals is unfavorable.The flotation test results of artificial mixed ore show that CTAB has a better flotation separation perfprmance.The adsorption capacity,Zeta potential and infrared spectroscopy characterization analysis of the collector to the mineral were carried out.The results of the adsorption capacity of the collector show that kaolinite is easier to adsorb the agent than diaspore.Zeta potential results show that before the collector is adsorbed,the point zerocharge of kaolinite is 4.8 and that of diaspore is 2.5.After the collector is adsorbed,the point zerocharge is increased.Therefore,when the p H of the slurry is between 2.5 and 4.8,the two minerals have different charges,which provides a theoretical basis for the differential adsorption of ionic collectors.Infrared characterization results show that the adsorption of collectors and minerals is physical adsorption.The molecular dynamics simulations of collectors and minerals were carried out.Calculations of crystal properties indicate that the floatability of kaolinite is greater than that of diaspore.Energy calculations show that the interaction energies between CTAB,kaolinite and diaspore are-502.0kcal/mol and 252.7kcal/mol,respectively,and the difference between the two is 249.3kcal/mol,which is significantly higher than DTAB and TTAB.In addition,the total interaction energy between the collector CTAB and kaolinite is about twice the total interaction energy with diaspore.These results indicate that CTAB molecules are preferentially adsorbed on the surface of kaolinite and have a higher High selectivity.Concentration distribution calculation results indicate that as the number of carbon atoms in the collector increases,the adsorption of three drugs DTAB,TTAB,and CTAB becomes tighter while the distance to the mineral surface is hardly changed.The calculation results of the mean square displacement show that the diffusion coefficient is CTAB>TTAB?DTAB during the interaction between the collector and kaolinite.It can be seen that CTAB molecules are more easily adsorbed on the surface of kaolinite.The flotation test was carried out with CTAB and DDAA mixed collector.The flotation results show that the recovery rate of the three gangue minerals is improved while the recovery rate of diaspore is suppressed.The flotation test of mixed ores and actual minerals obtained good flotation separation effect.The adsorption capacity,Zeta potential,infrared characterization and XPS test results show that the addition of DDAA is beneficial to expand the difference in the adsorption capacity of CTAB on the surface of diaspore and kaolinite,which in turn is beneficial to flotation separation.The flotation mechanism process of the mixed agent was further studied by molecular dynamics simulation calculation..The calculation results of the interaction energy show that DDAA is preferentially adsorbed on the surface of diaspore while CTAB is preferentially adsorbed on the surface of kaolin.Therefore,the addition of DDAA effectively inhibits the adsorption of CTAB on the surface of diaspore.The concentration distribution data show that DDAA is mainly distributed in one layer on the surface of diaspore while the surface of kaolinite is distributed in multiple layers.