In the process of coal mining, a large amount of coal resources are wasted by reserving coal pillars to prevent the collapseof gob. In order to ensure the sustainable development of coal resources, it is urgent to solve the problem of " three pressure coal" , so it isimperative to study the filling mining technology. Using coal gangue as aggregate, fly ash and a small amount of cement as cementing material, combining with the different characteristics of fly ash in different power plants, fly ash compounding technology was adopted to solvethe problems of poor slurry fluidity and low strength, and a mine filling material was prepared with high solid waste content, low cost, highflow and high strength. The effects of composition, morphology and particle size of fly ash on the strength and fluidity of filling materials in3 power plants were analyzed. The results show that the spherical shape of pulverized coal furnace fly ash FA1 can significantly improve thefluidity of backfill material, while the irregular shape of circulating fluidized bed fly ash FA2 and FA3 has no significant effect on improving the fluidity of backfill material, but it has a significant effect on improving the strength of backfill due to the large amount of active calcium oxide. The higher the content of active calcium oxide in fly ash, the higher the strength of backfill, but the worse the fluidity.Therefore, by combining pulverized coal furnace ash FA1 with circulating fluidized bed ash FA3, the fluidity is improved and the compressive strength is maintained. The results show that when 20% FA1 and 80% FA3 are combined and 94% of the cement is replaced by flyash, the prepared slurry has good fluidity, and the 28 d strength is up to 4.5 MPa, which meets the C4 grade in the line standard JC/ T2468—2018 " Cement-based Backfill Materials" , that is, the 28-day strength is ≥4 MPa. The research shows that the ratio of clean pulpto gangue is 1 ∶ 4, and the gangue of the mine filling material prepared has good encapsulation property, and the strength of 28 d is4.2 MPa, which is slightly lower than that of the clean pulp. When the ratio of clean pulp to gangue is 1 ∶ 6, the packing propertyof gangue prepared is poor, and the strength of 28 d is only 1.3 MPa. Therefore, the optimal ratio of clean pulp to gangue is 1 ∶ 4, that is,the maximum amount of gangue accounts for 80% of the filling material, cement accounts for 1.2%, and fly ash accounts for 18.8%.

左然芳(1987—),女,安徽蚌埠人,工程师,博士。E-mail:zrfzgdz@126.com

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ZUO Ranfang,FENG Bo,DONG Yang,et al.Coal mine filling material based on cement with high solid waste content[J].Clean Coal Technology,2023,29(11):154-160.