Preparation Of High Concentration Coal Water Slurry Of Lignite Based On Particle Surface Modification

This paper is based on coal water slurry(CWS)gasification technology and lignite was selected as the main material in our work.From the concerning of improving the hydrophobicity of the coal,the second fluid and the second particle were chose to modified the coal.The effect of particle surface modification on the preparation of coal water slurry was investigated by examining wettabilities of coal and rheological properties of slurryThe effect of the second fluid on the slurryability of CWS of lignite was systematically examined.the principles of selection of the second fluid,the effect of the second fluid amount on the slurryability,the existence state of the second fluid in the CWS and the modification effect of composite second fluid were examined in this part.The results show that the contact angle of raw Inner Mongolia lignite is 57.3°,and the maximum slurry concentration(MSC)is only 53.4wt%.Differently,the contact angle of the coal modified with the second fluid(kerosene)is 78.20,and the MSC is correspondingly increased to 55.5wt%The images of the confocal laser scan microscope showed that the second fluid formed an oil film on coal particles uniformly,which were uniformly dispersed without large tissue.The effect of the second particle on the slurryability of CWS of lignite was systematically investigated.A hydrophobic second particle was added to the second fluid to produce a multi-stage structure on coal surface and further improved its hydrophobicity.The selection of the second particles,the wettabilities,diameter and amount of the second particles on the slurryability of CWS,and the effect on slurryability of CWS of adding the second particle to the composite second fluid were also studied in this part.The results show that after the modification of adding the second particles(petroleum coke)in composited second fluid(silicone oil and kerosene),the contact angle of the coal increased to 92.3°,and the MSC of it increased to 56.5wt%.The surface modification of the second particles by the second fluid was investigated.This part,we used the second fluid(kerosene)infiltrated petroleum coke,and a hydrophobic surface was obtained by the way that solvent is volatilized free and the surface wettability were examined.The effects of the wettability,diameter and content of the second particles on the wettability of the surface were investigated.The microstructure of the hydrophobic surface was observed using electron microscopy,and the results show that the coarse disordered structure is responsible for the surface sup-hydrophobicity.The addition of wood wax oil is beneficial to increase its mechanical strength,otherwise,it would reduce the surface hydrophobicity to a certain extent.The hydrophobic surface prepared by solvent evaporation stably obtained a static contact angle of above 1400°and a rolling angle of less than 10°.