聚合硫酸铝调控硫酸盐激发尾砂充填材料工作性能与微观结构的研究

Controlling the Workability and Microstructure of Sulfate Activated Tailings Based Backfills Using Polyaluminum Sulfate

目前细粒级尾砂充填体存在充填浓度低、凝结时间长、力学性能差等问题。研究采用大掺量矿渣水泥作为细粒级尾砂的胶结剂,硫酸钠为激发剂,通过聚合硫酸铝调节改善新拌砂浆的工作性能和硬化体的力学性能,对充填体水化反应、物相组成以及微观形貌进行分析。结果表明,适量聚合硫酸铝的掺入能够显著缩短硫酸盐激发矿渣水泥基充填材料的凝结时间,提高其力学性能。聚合硫酸铝掺量超过5%时会导致充填体凝结时间大幅延长,7 d后仍不能硬化形成强度。研究表明聚合硫酸铝促进了硫酸盐激发矿渣水泥的水化产物AFm相向针棒状钙矾石相转变,钙矾石晶体相互搭接,形成空间三维网络,立体编织效果,提高充填体密实度,提升了细粒级尾砂充填材料的性能。

Lack of mechanical performance and slow setting time are the main issues of current fine tailings-based backfills when using sulfate activated slag cement as the binder.This research aims to investigate the feasibility of using polyaluminum sulfate(PAS)to shorten the setting time and promote the strength development of fine tailings-based backfills.The effects of PAS on reaction kinetics,hydration products and microstructure development of sulfate activated slag cement were also characterized.The results show that the incorporation of PAS shortens the setting time of backfills and promotes its compressive strength at all curing ages.Nevertheless,a high dosage of PAS leads to a significant delay of the hydration of backfills.The samples,observed at the current study,are not hardened after 7 d of curing when the dosage of PAS is higher than 5%.Results reveal that the incorporation of PAS promotes the conversion of AFm phase to needle-shaped ettringite phase in sulfate activated slag cement-based backfills that densify the microstructure,and that promotes the strength development of backfills.