低成本钢尾渣-矿渣基矿山充填料的优化开发

Optimized development of steel slag tailings-GGBS based low-cost backfill material

为实现多固废协同利用、降低充填成本,在矿渣基全粒级细尾砂胶结充填料基础上,以流动性和抗压强度为表征,利用热闷钢渣磁选尾渣(钢尾渣)替代部分矿渣作为胶凝材料,脱硫灰和水泥熟料替代部分专用添加剂作为外加剂,采用正交试验探寻掺量规律,优化固体填充料配比,开发钢尾渣-矿渣基软性矿山充填料,并研究了外加剂与胶材比、灰砂比等因素的影响。对比分析了矿渣基准组、钢尾渣-矿渣基准组(B1)、强度最优外加剂组分钢尾渣-矿渣组(B7)等3组充填料的微观形貌及XRD图谱以探究其水化机理。结果表明,钢尾渣替代矿渣量增加、外加剂与胶材比减小,充填料浆流动性改善,但充填体抗压强度下降。强度正交试验结果表明,钢尾渣掺量大小决定强度低高,脱硫灰掺量宜高于水泥熟料。进一步调整外加剂组分配比,在灰砂比为1∶6、钢尾渣替代矿渣为20%条件下,找出B7组外加剂组分为脱硫灰、水泥熟料分别替代30%、20%专用添加剂,B7组料浆扩展度为143 mm,充填体形貌为富铁绿泥石胶结假方体钙硅灰石,28 d抗压强度达2.13 MPa,较基准组低0.19 MPa,较B1提高0.26 MPa。该替代方案满足现场充填C2级强度的要求,改善流动性并显著降低了充填成本。优化的外加剂组分配比在灰砂比为1∶4条件下同样具有强度优化作用,但较灰砂比为1∶6条件下低。

In order to realize the synergistic utilization of wastes and reduce the backfill cost,this paper took the GGBS-based fine unclassified tailings cemented backfill material as the benchmark,and the flow of backfill slurry and backfill strength as the characteristics to carry on research.For developing of steel slag tailings-GGBS based soft mine backfill material,solid materials ratios were optimized.Hot stuffy steel slag magnetic selection tailings(steel tailings)were used to replace part of the GGBS as cemented material,while desulfurization ash and cement clinker replaced part of the special additive as admixtures.The orthogonal experiments were used to explore the mixing rules,and the influences of cement-sand ratio and the ratio of admixtures to binder were also researched.The micromorphology and XRD maps for backfills of GGBS-based,steel tailings-GGBS based(B1)and steel tailings-slag group with optimum strength admixture(B7)based were analyzed to explore their hydration mechanisms.The results show that with the increase of slag replaced by steel tailings and the decrease of admixture to binder ratio,the backfill strength decreases and the flow of backfill slurry improves.Strength orthogonal experimental results show that the strength is determined by content of steel tailings,and mixing content of desulfurization ash should be more than cement clinker.Under the condition of 1:6 cement-sand ratio and 20%replacement ratio of steel tailings to GGBS,the proportion of admixtures was further adjusted.The optimized admixtures of B7 were that desulfurization ash and cement clinker replaced special additive by 30%and 20%,respectively,the flow was 143 mm,and micromorphology was iron-rich chlorite cemented false cube crystalline wollastonite.The backfill strength was 2.13 MPa in 28 days,which was 0.19 MPa lower than that of GGBS-based group and 0.26 MPa higher than that of B1.The replaced alternative scheme meets the application requirement of C2 strength,which increases flow and reduces backfill costs significantly.The optimal admixture also has strength optimization effect at 1:4 cement-sand ratio but it is worse than 1:6 cement-sand ratio.