| Although the reserves of magnesium ore are abundant in China,the high-quality mineral resources are scarce currently.High-grade magnesium materials have high requirements for the purity of magnesite.The flotation has difficult separation effect on quartz in the form of inclusions in magnesite ores,and flotation tailing occupies cultivated land and pollutes the environment.Based on this,this article takes a magnesite ore in Dashiqiao,Yingkou,Liaoning Province as the research object.Bacterial pretreatment and flotation were used to remove the silicon-containing minerals from the magnesite ore to obtain high grade magnesite which meets the MS93A standard for the preparation of magnesia,and the tailing was used to prepare magnesium sulfate.The pretreatment-reverse flotation-tailing sulfuric acid leaching for the comprehensive utilization process of magnesium resources in low-grade magnesite was formed.The main findings are as follows.A silicate bacterium named as TG-08 was obtained for the flotation desilication of magnesite ore.And its growth characteristics were studied to determine its optimum growth conditions:shaking speed 100 r/min,culture temperature 38?,initial pH of the culture medium 7,and the volume fraction of bacteria of the shake flasks was 5%.The optimum process conditions for bacterial pretreatment-dodecylamine reverse flotation was determined:50 g of magnesite ore and 100 ml liquid medium,TG-08 bacterial with 10%was vaccinated and was cultured on a shaker for 3 days and the medium was removed,the flotation desiliconization is carried out at a flotation system with a pH value of 8,a water glass dosage of 200 g/t,and a dodecylamine dosage of 300 g/t.The flotation concentrate with MgO grade and recovery rate were 46.37%and 68.46%,and the SiO2 grade is 1.28%.In the dodecylamine system,The flotation concentrate with MgO grade and recovery rate were 45.81%and 73.62%,and the SiO2 grade was 2.08%.By comparison,bacterial pretreatment can improve the flotation index.The pretreatment mechanism of TG-08 bacteria was studied to improve the reverse flotation desilication of magnesite ore.magnesium ore and quartz are pretreated by TG-08 bacteria,the surface properties,ion concentration of the bacterial culture solution,and pH change indicate that quartz could be corroded by TG-08 bacteria and the contact sites with dodecylamine increased,polysaccharide of TG-08 bacteria attached to the surface of magnesite and making it hydrophilic precipitation.The interface difference of magnesite and silicate minerals was strengthened,improving the flotation separation effect of magnesite ore.The interaction between quartz and agents,magnesite and agents before and after pretreatment with TG-08 bacteria was simulated by using Material Studio.It can be concluded that the quartz surface is more likely to adsorb with dodecylamine after pretreatment with TG-08 bacteria,and the polysaccharides compete with dodecylamine in the magnesite surface to inhibit the magnesite from floating.The simulation system further clarified the inherent causes of the desiliconization of magnesite ore by the reverse flotation of TG-08 bacteria.The influencing factors on the leaching of Mg in tailing were investigated.Tailings grinding to-0.074 mm,the reaction temperature was 80?,the reaction time was 2 hours,the amount of sulfuric acid was 1.5 mol/L,and the liquid-solid ratio was 3 ml/g,the Mg leaching rate can reach 84%.The leaching process of Mg was in accordance with the shrinking-core model of fluid-solid phase non-catalytic reaction,and the leaching process is controlled by diffusion and chemical reaction collectively.The research results of the paper have an important guiding role for the use of bacteria to pretreat flotation magnesite and provide strong theoretical basis for utilization of low-grade magnesite. |
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