Study on alteration evolution and dust reduction mechanism of coal with different metamorphic degrees by water injection
In order to explore the effect of water on the microstructure of coal,the evolution law of water-coal alteration and the mechanism of dust reduction,focusing spectrum micro-scope,fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS)and uniaxial compression were used.The changes of coal surface morphology,mechani-cal properties and functional groups before and after water immersion alteration of lignite,Gaojiabu bituminous coal and Zhaogu anthracite in Wudong coal mine were comprehensively analyzed.The macroscopic and microscopic influence of water-coal alteration on coal dust re-duction was expounded and the evolution law and dust reduction mechanism of water injection of coal with different metamorphic degrees were revealed.The results show that the local rela-tive plastic deformation ability of coal is enhanced after alteration,and more energy of coal is used for crack closure and friction consumption between pores,and coal fragmentation needs to consume more released energy density Uf.With the increase of the metamorphic degree of coal,the proportion of polar hydrophilic oxygen-containing functional groups decreases,water-coal alteration weakens,and water molecules are adsorbed on the surface of coal macromole-cules through adhesion and surface tension,thus reducing the dust concentration.After water-coal alteration,oxygen-containing functional groups and water molecules are adsorbed to form hydrogen bonds,and the adsorption distances are all within 2 Å.Hydrogen bonds enhance the bonding strength and stickiness between dust particles,and dust particles combine into larger aggregates,which are easier to adhere to the rough surface of coal.
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