电石渣—脱硫石膏复合激发充填材料性能及微观结构

针对传统充填材料高碳排放、高成本问题,以“绿色矿山”为理念,选用工业固废电石渣、脱硫石膏和矿渣为胶凝组分,以尾矿砂为骨料制备充填材料。利用X射线（XRD）、扫描电镜（SEM）和能谱分析(EDS)等手段研究充填料水化产物及微观形貌,并开展工作性能、力学性能和重金属固化性能试验。结果表明：所开发的充填材料凝结时间和流动度均满足矿山充填工程要求,充填体7、28 d抗压强度可达4.6、7.9 MPa,充填体浸出液中Pb、Zn浓度低于规定限值。电石渣内的氢氧化钙提供碱性环境,脱硫石膏提供硫酸根离子,两者对矿渣内的硅铝质原料复合激发,生成以钙矾石和C-A-S-H凝胶为主的水化产物。大量针棒状结构的钙矾石晶体及网状结构的C-A-S-H凝胶相互穿插,并且与尾砂颗粒紧密结合,随着龄期延长,结构更加致密,使充填体具有良好的力学性能。

Properties and microstructure of backfilling material activated by carbide slag and desulfurized gypsum

To deal with the high carbon emission and high cost of traditional backfilling materials, taking "green mine" as the concept, industrial solid wastes such as carbide slag, desulfurized gypsum and slag were used as cementitious components, and tailings were used as aggregates for backfilling materials. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to examine the hydration products and microstructure of the backfilling materials, and the working performance, mechanical properties and heavy metal solidification performance tests were carried out. The results show that the setting time and fluidity of the developed backfilling materials met the requirements of mine backfilling project. The maximum compressive strength of the backfilling body can reach up to 4.6 MPa and 7.9 MPa at 7 d and 28 d, respectively, and the concentrations of Pb and Zn in the leaching solution of the backfilling body were lower than the specified limits. Calcium hydroxide in carbide slag provided alkaline environment, and desulfurization gypsum provided sulfate ion. The aluminosilicate material in slag is activated by both, producing the hydration products that mainly consist of ettringites and C-A-S-H gels. A large number of needle like ettringite crystals and reticulated C-A-S-H gels interspersed with each other, and tightly bonded with tailings particles. With extension of age, the structure became more compact, and the backfilling would be of good mechanical properties.