黔西南汞铊矿废弃物中污染物释放的联合调控研究

Release Characteristics and Joint Control of Typical Highly Toxic Pollutants in the Waste of Mercury-Thallium Mine in Southwest Guizhou

为评价植生改良与先锋植物联合调控作用对矿产采冶废弃物中污染物迁移的控制情况,以黔西南兴仁市滥木厂大量露天堆存的汞铊矿废弃物(采冶废渣、尾矿、废石等混合物)为研究对象,选择当地广泛存在的碳酸盐岩、腐熟牛粪作为植生改良剂,并种植三叶草和黑麦草作为先锋植物进行联合调控,通过淋滤实验评价其对废弃物中高毒性污染物Hg、Tl、As和Sb释放的抑制效果。结果表明:对照组废弃物淋滤3次所得淋滤液中Hg、Tl含量平均为14.8μg/L和170.6μg/L,As和Sb平均为22.1μg/L和4.9μg/L,在雨水淋溶下具有持续释放进入环境的风险;联合调控可对废弃物中Tl和Hg的释放有明显的抑制效果,其中淋滤液Tl含量降为对照的12.2%~54.1%,10%碳酸盐岩梯度的混种组淋滤液Tl含量为19.6μg/L,效果最好;5%、10%碳酸盐岩梯度的三叶组和混种组淋滤液中Hg含量显著低于对照水平(p<0.05),较对照降低34.5%~47.9%;而联合调控则致使废弃物中As、Sb释放,相关性分析表明,植生改良剂添加引起的废弃物基质中溶解性有机质含量增加与植物诱导下游离氧化铁的溶解可能是导致As、Sb释放的关键因素。形态分析结果表明,联合调控促使汞铊矿废弃物中Hg、Tl向残渣态转变,而促使残渣态As、Sb占比下降导致其活化。综上,对汞铊矿废弃物采用植生改良剂-先锋植物联合调控可显著抑制Hg、Tl的释放,但需考虑所加植生改良剂中溶解性有机质增加及废弃物基质中游离氧化铁溶解引起的As、Sb活化与释放带来的环境风险。

In order to evaluate the effect of plant growth condition modifier and pioneer plants on the control of pollutants migration in the waste of mining,mercury-thallium wastes,including the mining and metallurgical waste residues,tailings and waste rock in Lanmuchang,Xingren city of Southwest Guizhou was studied by adding carbonate rock and decomposed cow manure as growth condition modifier,and by planting with Trifolium repens and Lolium perenne as pioneer plants for joint regulation,to evaluate the inhibition effect of these measures on the release of toxic pollutants Hg,Tl,As and Sb from waste by leaching experiments.The results showed that the average content of Hg and Tl in the leachate obtained from the control group was 14.8μg/L and 170.6μg/L,respectively,and the average content of As and Sb was 22.1μg/L and 4.9μg/L,respectively.There is a risk of continuous release of heavy metals into the environment,joint regulation has a significant inhibition effect on the release of Tl and Hg.The content of Tl in the leachate is reduced to 12.2%-54.1%of the control,with the T10 treatment has lowest Tl of 19.6μg/L,which has the best inhibition effect,Hg content in the leachate of the S5,S10,T5 and T10 treatment was significantly lower than the control level(p<0.05),with a reduction of34.5%-47.9%,while,the combined regulation resulted in the release of As and Sb in the waste.Correlation analysis indicated that the increase in the content of dissolved organic matter in the waste caused by the addition of plant growth condition modifier and the Fed induced by plants might be the key factor of the release of As and Sb.The chemical speciation analysis suggested that the joint regulation promotes the transformation of Hg and Tl in the waste to the residue state,and decrease of the proportion of the residue state of As and Sb.In summary,the use of plant growth condition modifier-Pioneer Plants joint regulation of mercury-thallium mine waste pollutants can significantly inhibit the release of Hg and Tl,but increase the release of As and Sb,which was induced by the increase of dissolved organic matter by adding plant growth condition modifier and this should be considered for this joint control.