The Desulfurization And Ash Reduction Of Coal By Flotation Process

With the increasingly strict requirements of environmental protection in China,the efficient utilization and clean conversion of coal has become a research hotspot.Flotation method is widely used in coal desulfurization because of its simple process and low cost.In this paper,the desulfurization and ash reduction of Shanxi ZY bituminous coal and ZF bituminous coal were carried out by flotation method.The effects of collector,foaming agent and inhibitor on the flotation were studied.The flotation process was optimized by orthogonal experiment and BBD response surface method respectively.To explore the mechanism of flotation desulfurization and ash reduction,the coal samples before and after flotation were analyzed and characterized by FTIR,XRD and Zeta potential.Firstly,the desulfurization and ash reduction of ZF bituminous coal was carried out by flotation test.The results show that the Kerosene emulsification can increase the yield of concentrate.Among them,the non-ionic surfactant Span20 emulsified Kerosene has good stability and can effectively improve the desulfurization and deashing effect of ZY bituminous coal flotation.While the cationic surfactant CTAB emulsified Kerosene has little effect on the desulfurization and deashing effect.Anionic surfactant SDBS emulsified Kerosene has poor stability and reduces the flotation desulfurization and deashing effect.The flotation concentrate yield using Secoctanol as frother is much higher than that of Pine oil,and the desulfurization and ash reduction effect of CTAB-emulsified Secoctanol is better than that of Secoctanol.Through single factor test,the process conditions of ZF bituminous coal flotation process were determined as follows: in the flotation process,inhibitor was first added and then collector was added;the action time of Span20-emulsified Kerosene collector was 60s;the action time of CTAB-emulsified Secoctanol foaming agent was 10s;the concentration of coal slurry was 100g/L;the action of inhibitor YC was 3min;and the foam was scraped for 5min.BBD response surface method was used to optimize the dosage of reagents in the flotation process of ZF bituminous coal.And it was determined that the flotation effect of ZF bituminous coal was the best when the dosage of collector,foaming agent and inhibitor were 300g/t,116g/t and 123g/t respectively.Under these conditions,the predicted values of the desulfurization rate,the flotation perfection index and the deashing rate are 9.45%,17.54% and 28.51%,respectively.The error between the predicted values and the verification test results is small,which indicates that The response surface method to optimize the flotation process is reliable,and the prediction is highly credible.Secondly,flotation desulfurization and ash reduction of ZY bituminous coal were also studied.The results show that Span 20-emulsified Kerosene with an oil-water mass ratio of 1:1 has good flotation effect and high stability.The desulfurization and deashing effect of Pine oil is better,but the yield of flotation concentrate is not as good as that of Secoctanol.By CTAB-emulsified Secoctanol as the foaming agent,the yield of concentrate is improved,and the problem of sampling because of its small amount can be solved.Through single factor test,the action time of ZY bituminous coal with Span20-emulsified Kerosene is 90 s,the action time of CTAB-emulsified Pine oil is 30 s,and the scraping foam time is 3min.ZY bituminous coal flotation process was optimized by orthogonal test.The test results show that when the amount of collector,frother and the concentration of coal slurry are 400g/t,100g/t and 80g/L respectively,the concentrate yield,the desulfurization rate and the deashing rate of ZY bituminous coal flotation can reach 89.93%,12.11% and 30.61%.Finally,the inhibitor of ZY bituminous coal was screened,and the results showed that the flotation effect is better using the 125g/t of YC and the 200g/t of HANa;the flotation effect of TGA is not well.