National Institute of Clean-and-Low-Carbon Energy,CHN Energy

煤炭开采过程中通过预留煤柱方式防止采空区塌陷,导致大量的煤炭资源被浪费。为保证煤炭资源的可持续发展,解决“三下压煤”问题迫在眉睫,因此进行充填开采技术研究势在必行。利用煤矸石作为骨料,粉煤灰及少量水泥为胶凝材料,结合不同电厂粉煤灰特性差异,采用粉煤灰复配技术解决浆体流动性差和强度低等问题,制备一种高固废掺量、低成本、高流动、高强度的矿井充填材料。分析了3个电厂粉煤灰的成分、形貌、粒径等性能对充填材料强度、流动性的影响。研究表明,煤粉炉粉煤灰FA1因球形形貌可显著提高充填浆体材料流动性,循环流化床粉煤灰FA2和FA3因形貌不规则,对改善浆体流动性作用不显著,但因含有大量活性氧化钙,对提高充填体的强度非常明显;粉煤灰中活性氧化钙含量越高,充填体强度越高,但流动性越差。因此通过将煤粉炉灰FA1与循环流床灰FA3复配,实现提高流动性同时,保持较高抗压强度。结果表明,20%FA1与80%FA3复配,粉煤灰取代94%的水泥,制备的净浆流动度较好,同时28d强度高达4.5MPa,满足行标JC/T2468—2018《水泥基回填材料》中C4等级,即28d强度≥4MPa。进一步将净浆与矸石复配,研究表明净浆与矸石比例为1∶4,制备的矿井充填材料矸石包裹性好,28d强度为4.2MPa,较净浆略降低;当净浆与矸石比例为1∶6时,制备的矿井充填材料矸石包裹性差,28d强度仅1.3MPa。因此净浆与矸石最佳比例为1∶4,即矸石最大用量占充填材料的80%,水泥占1.2%,粉煤灰占18.8%。

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%.

国家能源投资集团有限责任公司科技创新资助项目(GJNY-20-111);国家重点研发计划资助项目(2019YFC1904302)

左然芳,冯波,董阳,等.高固废掺量水泥基矿井充填材料[J].洁净煤技术,2023,29(11):154-160.

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.