State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China.
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China.
Chemosphere. 2022 Mar;291(Pt 1):132710. doi: 10.1016/j.chemosphere.2021.132710. Epub 2021 Oct 27.
Recycling mining wastes to produce cemented tailings backfill (CTB) is the optimal approach to eliminate the environmental pollution caused by their accumulation. However, its low strength limits its application. Using calcium formate (CF) as an accelerator for improving its mechanical properties is of great significance to promote sustainable development. The effects of CF dosage and curing time on dilatancy deformation, compressive strength and microstructure of CTB were investigated through mechanical compression, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) tests. The strengthening and deterioration mechanisms of CF dosage on CTB were revealed, and its engineering practicability was systematically evaluated. The results show that the variation of volumetric strain in the dilatancy deformation stage firstly increase and then decrease with the increases of CF dosage and curing time. The relationship between CF dosage and compressive strength can be characterized by quadratic polynomial, and the optimal CF dosage characterizing the superior mechanical property of CTB is between 1.60 and 1.84. The supplement of CF reduces the size and distribution of microcracks and micropores, thereby optimizing the microstructure of CTB. Nevertheless, the excessive dosages of CF deteriorate the microstructure of CTB and produce serious defects, which cannot be effectively filled by hydration products, thus weakening the strength property of CTB. This study provides an effective accelerator for improving the mechanical properties of CTB, which is of great significance to promote the recycling of tailings.
回收利用采矿废物生产胶结尾矿充填体（CTB）是消除其堆积造成的环境污染的最佳方法。然而，其低强度限制了其应用。使用甲酸钙（CF）作为加速剂来提高其力学性能对于促进可持续发展具有重要意义。通过力学压缩、扫描电子显微镜（SEM）和能谱仪（EDS）测试，研究了 CF 用量和养护时间对 CTB 膨胀变形、抗压强度和微观结构的影响。揭示了 CF 用量对 CTB 的增强和劣化机制，并对其工程实用性进行了系统评价。结果表明，膨胀变形阶段的体积应变随 CF 用量和养护时间的增加先增加后减小。CF 用量与抗压强度的关系可用二次多项式来描述，CTB 力学性能优异的最佳 CF 用量在 1.60 和 1.84 之间。CF 的补充减少了微裂纹和微孔的大小和分布，从而优化了 CTB 的微观结构。然而，CF 的过量用量会恶化 CTB 的微观结构，并产生严重缺陷，这些缺陷不能被水化产物有效填充，从而削弱 CTB 的强度性能。本研究为提高 CTB 力学性能提供了一种有效的加速剂，对于促进尾矿的回收利用具有重要意义。
