Study On Desulphurization Of Low-rank Coal By Reverse Flotation With Low Temperature Plasma

The clean utilization of coal is the key to coordinate the utilization of resources and the sustainable development of environment.Low rank coal plays an important role in the reserves of coal resources in China.It is of great significance to study the new low rank coal separation technology because of the unsatisfactory desulfurization effect.In this paper,Burte mine in Shendong mining area of low rank coal as the research object,in the low temperature plasma treatment mainly to strengthen the anti flotation desulfurization technology research.By means of artificial mixed minerals flotation tests of pure coal and pyrite flotation tests and the effect of low-temperature plasma and inhibitor on the flotation behavior of pure minerals;combined with the contact angle,scanning electron microscope,energy spectrum analysis,X ray photoelectron spectroscopy analysis,research on the mechanism of low temperature plasma on the surface of minerals in Shendong;low rank coal mine as the actual mineral flotation test,preliminary construction to strengthen the anti flotation desulfurization technology with low temperature plasma treatment.The results of pure mineral flotation test show that the purpose of separating the pure coal from the pyrite can be achieved by the low temperature plasma treatment.When the low temperature plasma is treated for 2 minutes,the recovery rate of pyrite single mineral is 75.82%,the recovery rate of pure coal is 18.21%,and the gap is obvious.The flotation results of pure coal and pyrite mixed according to the mass ratio of 9:1 after treated with low temperature plasma display,2 minutes later,the collector of butyl xanthate dosage for the flotation separation of the best 600g/t,the sulfur content of coal to 0.51%,desulfurization rate reached 89.76%.The use of inhibitor dextrin alone can also achieve the effect of reverse flotation,but the effect of desulphurization is far less than that of low temperature plasma.The synergistic inhibition test results of low temperature plasma and inhibitor show that the addition of dextrin has a negative effect on the effect of low temperature plasma enhanced reverse flotation desulfurization.The surface contact angle test results of pure coal and pyrite before and after the treatment of low temperature plasma show that the wettability difference between the two surfaces is significantly increased after 2 minutes treatment.SEM analysis showed that before and after treatment,the surface morphology of pure coal changed greatly,and the pores and ravines increased significantly,and the surface layer was obviously destroyed,but the surface of pyrite changed little.The results of EDS and XPS showed that the results were basically the same.The contents of O in treated coal and pyrite increased significantly,and the content of C decreased.The content of S on the surface of pyrite decreased.XPS narrowband analysis showed that the surface of pure coal rapidly entered the deep oxidation state when the plasma was treated for 1to 4 minutes.Most of the C-H bonds were oxidized to hydrophilic C-O,C=O and O-C=O containing oxygen-containing functional groups,and the hydrophilicity increased significantly.While pyrite is oxidized slowly,the relative content of FeS₂ on the surface decreases,and other compounds including Fe₂?SO₄?₂ and FeSO₄,polysulfide and Fe₂O₃,FeOOH and other iron oxides are formed,and the floatability of pyrites is changed little.The results of actual mineral flotation test of low rank slime showed that a two stage flotation process with a positive flotation and two stage reverse flotation desulfurization achieved good flotation effect,and the flotation index of the two stage flotation method was significantly improved compared with the traditional positive flotation.