Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China, Xi'an, 710054, China.
Environ Sci Pollut Res Int. 2023 Nov;30(54):114920-114935. doi: 10.1007/s11356-023-30554-0. Epub 2023 Oct 25.
With the mass production of coal-based solid waste, coal mine filling can effectively consume it. The coal gasification slag is modified and prepared as coal mine filling material to meet the relevant technical requirements, which can realize the recycling of coal mine → coal chemical industry → coal mine. In this paper, in order to explore the evolution law of the mechanical properties and pore structure characteristics of the modified coal gasification slag-cement cemented paste backfill (MCGS-CPB) prepared by sodium sulfate excitation coal gasification slag, a combined macro-meso-micro testing method is used. MCGS-CPB with different sodium sulfate contents (1~5%) were prepared and tested for uniaxial compressive strength (UCS), mercury intrusion (MIP) and microscopic tests. The results show that sodium sulfate has a significant effect on the UCS and pore structure characteristics of MCGS-CPB. The mechanical properties and pore structure characteristics of MCGS-CPB were best when sodium sulfate was doped at 3%; the mechanical properties and pore structure characteristics of MCGS-CPB were deteriorated when the addition of sodium sulfate is higher than 3%. On the meso-scale, when sodium sulfate was doped with 3%, the more harmful pores of MCGS-CPB gradually changed into harmless, less harmful, and harmful pores, and the macroscopic mechanical properties were gradually improved; when the addition of sodium sulfate is higher than 3%, the harmless, less harmful, and harmful pores of MCGS-CPB gradually changed into more harmful pores, and the macroscopic mechanical properties were deteriorated. On a microscopic scale, sodium sulfate can cause MCGS-CPB to form hydration products with expansion properties. The presence of a reasonable amount of sodium sulfate in the pores of MCGS-CPB is beneficial to the development of mechanical properties. However, excessive presence will lead to the formation of expansion stress, gradual formation of micro-expansion cracks, and deteriorate the macroscopic mechanical properties. Hence, the volcanic ash activity of coal gasification slag excited by external addition of sodium sulfate should not exceed 3%. This study provides a reference value for application ratio of sodium sulfate-stimulated MCGS-CPB used in coal mine filling design.
随着煤基固废的大量产生，煤矿充填可以有效地消耗它。将煤气化渣进行改性并制备为煤矿充填材料，以满足相关技术要求，可以实现煤矿→煤化工→煤矿的循环利用。本文为了探索激发煤制气渣的硫酸钠对改性煤气化渣-水泥胶结充填料（MCGS-CPB）的力学性能和孔结构特征演变规律，采用宏-细-微观相结合的测试方法。制备了不同硫酸钠掺量（1%~5%）的 MCGS-CPB，并进行了单轴抗压强度（UCS）、压汞（MIP）和微观测试。结果表明，硫酸钠对 MCGS-CPB 的 UCS 和孔结构特征有显著影响。当硫酸钠掺量为 3%时，MCGS-CPB 的力学性能和孔结构特征最佳；当硫酸钠掺量高于 3%时，MCGS-CPB 的力学性能和孔结构特征恶化。在中观尺度上，当硫酸钠掺量为 3%时，MCGS-CPB 的有害孔逐渐向无害、少害和有害孔转变，宏观力学性能逐渐提高；当硫酸钠掺量高于 3%时，MCGS-CPB 的无害、少害和有害孔逐渐向有害孔转变，宏观力学性能恶化。在微观尺度上，硫酸钠可以使 MCGS-CPB 形成具有膨胀性能的水化产物。MCGS-CPB 中存在适量的硫酸钠有利于力学性能的发展。然而，过多的硫酸钠存在会导致膨胀应力的产生，微膨胀裂缝的逐渐形成，从而恶化宏观力学性能。因此，通过外部添加硫酸钠激发的煤气化渣的火山灰活性不应超过 3%。本研究为煤矿充填设计中应用比例的硫酸钠激发 MCGS-CPB 提供了参考价值。
