碳酸盐激发胶凝材料性能优化及其在铅锌矿尾砂胶结充填中的应用

Research on the Modification of Carbonate-activated Binders and the Utilization in Lead/Zinc Mine Tailings based Cemented Paste Backfill

胶结充填是实现尾矿大宗资源化利用的有效途径,然而胶凝材料(水泥)的高成本限制了胶结充填的应用,因此亟待开发研究新型的充填胶凝材料。从实际工程应用的安全性和便利性角度出发,弱碱(如Na_(2)CO_(3))激发胶凝材料更适于胶结充填。然而其较低的反应速率导致胶结充填体早期强度较低,限制了采矿作业的顺利进行。针对这一问题,利用添加剂优化改性Na_(2)CO_(3)激发高炉矿渣作为胶凝材料用于胶结充填。通过探索不同添加剂对胶凝材料水化特性、反应产物以及对胶结充填样品流动性、抗压强度和重金属固化效率的影响,得出适合于铅锌矿尾砂胶结充填的胶凝材料配比。结果表明:当添加5 wt%煅烧白云石以及1 wt%碱式碳酸镁时,样品性能最优。当胶凝材料和尾砂质量比为1∶6、料浆浓度为76%时,充填体3 d和28 d抗压强度分别为1.41 MPa和3.89 MPa,并且重金属的浸出量符合国家相关标准。

Cemented paste backfill promotes the construction of green mine.However,as the main binder in CPB,the high cost of OPC limits the large-scale application of CPB.Thus,low-cost binders are needed.In this work,Na_(2)CO_(3)-activated blast furnace slag modified by different additives was used in CPB.The influence of additives on the properties of binder was investigated,including binder hydration,hydration products,flowability,compressive strength and heavy metals immobilization.The test results showed that mix proportion of binders with the best performance was found when adding 5 wt%calcined dolomite and 1 wt%hydromagnesite.When the mass ratio of cementitious material to tailings was 1∶6 and the slurry concentration was 76%,the com-pressive strength of backfill in 3 d and 28 d was 1.41 MPa and 3.89 MPa,respectively.Besides,heavy metals can be immobilized effectively.