赤泥基充填体力学和水化动力学研究

Experimental study on mechanics and hydration kinetic of red mud-based cemented paste backfill

充填开采是资源绿色开采的重要方式之一,可有效控制地表沉降和保障人员安全。对不同赤泥掺量的充填体进行水化热和力学测试并分析其演化规律,从微观尺度分析赤泥基充填体以解释强度变化的原因。最后,对最优配比的赤泥基充填体进行环境与经济效益分析。研究表明,赤泥基充填体的水化动力过程可分为结晶成核与晶体成长(NG)、相边界反应(I)和扩散(D)三阶段,水化度控制赤泥基充填体水化三阶段(NG-I-D)的进程。所有配比的赤泥基充填体均经历了NG-I-D阶段,相比于对照组,赤泥基充填体的α1较大,说明NG过程转变为I过程需要较大水化度,这与充填浆体的有效水灰比和成核作用有关。基于充填体强度指标,得出的优化配比是C-RM16。此外,赤泥基充填体的环境指标符合充填要求;同时经济效益分析表明,使用C-RM16配比的充填体可降低充填成本5.1~9.9元/m^(3),能实现可观的经济效益。

Cemented Paste Backfill(CPB)is one of the important modes of resource green mining,which can effectively control surface subsidence and ensure personnel safety.In this paper,the hydration heat test and mechanical properties test of CPB with different red mud dosages are carried out.Moreover,from the micro-scale,the red mud-based cemented paste backfill(RCPB)is analyzed to explain the reasons for the variation in compressive strength.Finally,the environmental and economic benefits of RCPB with the optimal ratio are analyzed.The test results show that the three stages of crystallization nucleation and crystal growth(NG),phase boundary reaction(I)and diffusion(D)can characterize the hydration process of RCPB.The hydration degree controls the process of the three-stage hydration(NG-I-D)of RCPB.All ratios of RCPB go through the NG-I-D stage,and theα1 of the RCPB is larger compared with the control group,indicating that the NG process is transformed into the I process only when the hydration degree is high,related to the effective water-cement ratio and nucleation of RCPB.Moreover,adding appropriate dosage of red mud can improve the performance of RCPB.Based on the strength index of backfill,the optimal ratio is C-RM16.In addition,the environmental indicators of RCPB meet the backfill requirements;the economic benefit analysis shows that RCPB with the ratio of C-RM16 can reduce the backfill cost by 5.1~9.9 Yuan/m 3 and achieve considerable economic benefits.