Wang Yiming, Wu Jiangyu, Ma Dan, Pu Hai, Yin Qian, Chen Weiqiang
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, 221116, Jiangsu, China.
State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining & Technology, Xuzhou, 221116, Jiangsu, China.
Environ Sci Pollut Res Int. 2023 Jan;30(2):2904-2917. doi: 10.1007/s11356-022-22436-8. Epub 2022 Aug 8.
The use of cement and fly ash (FA) to prepare cemented tailings backfill (CTB) lowers backfill mining costs while also reducing pollution caused by the accumulation of waste materials like tailings and FA, making it a green backfill mining process. While adding FA to CTB may reduce costs, too much FA might weaken CTB's strength property. Mechanical tests were used to explore the effects of FA content and curing time on the uniaxial compressive strength (UCS) and deformation modulus of CTB in this research. The effects of FA content on failure modes, strain energy, and crack evolution of CTB were studied using a numerical model that considered FA content and particle contact mode. The influence mechanism of different FA contents on CTB was also revealed at the microscopic level. The results demonstrate that the UCS of CTB has a quadratic polynomial and a linear relationship with FA content and curing time respectively, and that the elasticity modulus and secant modulus of CTB increase and then decrease with FA content under different curing times. The peak strain energy of CTB increases and subsequently declines with the FA content, and crack propagation inside CTB may be limited by regulating the FA content. A reasonable content of FA can optimize the size and distribution of CTB microscopic defects, enabling them to exhibit superior strength property. This study systematically explores the mechanism of different FA contents on the strength property of CTB from a macro-micro perspective, providing an essential reference value for improving the recycling of FA and waste residues such as tailings.
使用水泥和粉煤灰（FA）制备胶结尾矿充填体（CTB）可降低充填采矿成本，同时减少尾矿和FA等废料堆积造成的污染，使其成为一种绿色充填采矿工艺。虽然向CTB中添加FA可能会降低成本，但过多的FA可能会削弱CTB的强度性能。本研究采用力学试验探究了FA含量和养护时间对CTB单轴抗压强度（UCS）和变形模量的影响。利用考虑FA含量和颗粒接触模式的数值模型，研究了FA含量对CTB破坏模式、应变能和裂纹扩展的影响。还从微观层面揭示了不同FA含量对CTB的影响机制。结果表明，CTB的UCS分别与FA含量和养护时间呈二次多项式关系和线性关系，且在不同养护时间下，CTB的弹性模量和割线模量随FA含量先增大后减小。CTB的峰值应变能随FA含量先增大后减小，通过调节FA含量可限制CTB内部裂纹扩展。合理的FA含量可优化CTB微观缺陷的尺寸和分布，使其具有优异的强度性能。本研究从宏观-微观角度系统地探究了不同FA含量对CTB强度性能的作用机制，为提高FA和尾矿等废渣的资源化利用提供了重要参考价值。
