赤泥-黄土协同净化含Cd(Ⅱ)酸性矿井废水

Synergistic Purification of Acid Mine Drainage Containing Cd(Ⅱ)by Red Mud and Loess

为改善固体废弃物赤泥(red mud, RM)对含Cd(Ⅱ)酸性矿井废水(acid mine drainage, AMD)的净化能力,采用RM和天然黄土(loess, L)协同处理含Cd(Ⅱ)-AMD。通过批试验探究了RM和L的质量比、初始pH、接触时间、投加量和颗粒粒径对RM和L混合材料(RM-L)处理AMD效果的影响。结果表明:L显著改善了RM-L对酸性溶液的pH缓冲能力,降低碳酸盐结合态Cd(Ⅱ)的占比。RM-L协同处理含Cd(Ⅱ)-AMD的最优质量比为7∶3。增加最优质量比下RM-L(RM-L73)的投加量和减小RM-L73的颗粒粒径均能够提高Cd(Ⅱ)的去除效率。对于初始浓度为100 mg/L和初始pH=3的AMD,8 g/L的RM-L73对Cd(Ⅱ)的去除率可达99.2%,并能够将AMD的pH提高至8.0。通过扫描电镜(scanning electron microscope,SEM)和X射线衍射(X-ray diffraction,XRD)发现RM和L混合后的RM-L73颗粒具有良好的分散度,RM-L73中的方解石和硅铝矿物对AMD的中和以及Cd(Ⅱ)的去除发挥重要作用。

To enhance the purification capacity of solid waste red mud(RM)for acid mine drainage(AMD)containing Cd(Ⅱ),RM and loess(L)were used for synergistic treatment Cd(Ⅱ)-AMD in this study.The effects of RM and L mass ratio,initial pH value,contact time,dosage,and particle size on the treatment of AMD by RM and L mixture(RM-L)were investigated through batch experiments.The results indicate that L significantly improves the buffering capacity of the RM-L to AMD and reduces the proportion of carbonate speciation of Cd(Ⅱ).The optimum mass ratio of RM and L for co-treatment of Cd(Ⅱ)-AMD is 7∶3.The increase in dosage and decrease in particle size of RM-L under optimum mass ratio(RM-L 73)benefit the removal efficiency of Cd(Ⅱ).The RM-L 73 at 8 g/L can be removed 99.2%of Cd(Ⅱ)and increased the pH value of AMD to 8.0 when the initial concentration of AMD is 100 mg/L and the initial pH is 3.It is found that particles of RM-L 73 has great dispersibility after mixing RM and L,calcite and aluminosilicate minerals in RM-L 73 play a significant role in neutralization and Cd(Ⅱ)removal by scanning electron microscope(SEM)and X-ray diffraction(XRD)analysis.