微生物诱导矿化处理矿渣次数与灌浆方式研究

Study on the Treatment Times and Grouting Methods of Microbially Induced Mineralization for Tailings Slag

微生物矿化技术能改善尾矿渣的物理力学性质,同时可固定矿渣中的重金属离子。通过土柱试验开展了处理次数和方法对矿化效果的影响研究,采用自由入渗法、埋管注浆法及2种方法组合进行微生物诱导矿化试验,探讨了不同方式处理后土柱沿深度方向的矿化效果。研究结果表明:随着处理次数增加,土柱的重金属固定率、生成的碳酸盐含量和干密度增大,渗透系数和孔隙比降低。矿化处理后的各测试指标与处理次数之间满足较好的双曲函数关系,干密度和渗透系数分别与生成的碳酸盐含量成正、负线性相关关系。试验与曲线拟合结果显示:第3次处理后重金属固定率和生成的碳酸盐含量等测试指标的变化均趋于稳定,表明3次为最佳处理次数。自由入渗法处理后土柱的底部的渗透系数比顶部增大42.8%,表明矿化效果随深度明显减弱。埋管注浆处理后土柱的渗透性沿深度变化不大,矿化的均匀度最好。2种方法组合时可结合双方的优点,在提高土柱矿化效率的同时,还可降低土柱沿深度方向的不均匀性。

Microbially induced mineralization can improve physical and mechanical properties of tailings slag and fix heavy metal in slag at the same time.The influence of treatment times and method on mineralization effect was studied using soil column tests.The free infiltration method,buried tube grouting method and free infiltration combined with buried tube grouting method were used to carry out microbial induced calcite precipitation tests.The effects of different treatment methods on mineralization along the depth direction were discussed.The results showed that with the increase in treatment times,the heavy metal fixed rate,generated carbonate content and dry density of soil column increased,while the permeability coefficient and void ratio decreased.The relationship between the test indexes and the treatment times after mineralization treatment meets a good hyperbolic function,and the dry density and permeability coefficient are respectively positively and negatively linear-correlated with the carbonate formation rate.The test and curve fitting results showed that the change in heavy metal fixed rate,generated carbonate content and other test indexes tended to be stable after the third treatment,which means 3 times is the best treatment times.It was found that with the increase in depth,the permeability coefficient increased 42.8%at the bottom than that at the top of soil column treated by free infiltration method,which indicated that the mineralization effect became worse along depth.The permeability coefficient almost unchanged and the mineralization uniformity was the best along the depth when the soil column is treated by buried-tube grouting method.The free infiltration combined with buried tube grouting method had the advantages of both and could improve the mineralization efficiency,also could decrease the nonuniformity along the depth of the soil column.