钝化剂对铅锌尾矿砂中重金属的固化作用

铅锌尾矿砂重金属含量高,对环境危害大。为了减缓铅锌尾矿砂的重金属污染风险,采用室内培养实验方法,在铅锌尾矿砂中添加油菜秸秆、芒草秸秆、水稻秸秆、石灰和磷酸一铵等钝化剂,并通过DTPA及Tessier连续提取铅、锌、镉的化学形态,评价钝化剂对铅、锌、镉的移动性和生物有效性的影响。结果表明,油菜秸秆、芒草秸秆、水稻秸秆、石灰和磷酸一铵均显著地降低Cd的生物有效性及其迁移能力;磷酸一铵、油菜秸秆均能有效地降低尾矿砂中Pb的生物有效性及其迁移能力,尤其是磷酸一铵有极显著的效果;油菜秸秆、芒草秸秆、水稻秸秆和磷酸一铵均能有效地降低尾矿砂中Zn的生物有效性及其迁移能力。尾矿砂中DTPA态Cd、Zn与交换态、碳酸盐结合态Cd、Zn极显著正相关,DTPA态Pb与碳酸盐结合态Pb极显著正相关。从Pb、Cd、Zn生物有效态含量的减少方面考虑,油菜秸秆和磷酸一铵是较好的铅锌尾矿砂原位钝化剂。

Effects of Passivators on Stabilization of Pb, Zn and Cd in Lead and Zinc Mine Tailings

The tailings collected from Xiangxi lead and zinc （Pb/Zn） mine, in west of Hunan Province, China, had high concentrations of Pb, Zn and Cd. In order to reduce the risk of Pb, Zn and Cd in lead-zinc tailing, passivators including rape offal, grass straw, rice straw, lime and ammonium phosphate were added into the railings after 30 days incubation. DTPA method and Tessier sequential extraction procedures for different chemical fractions of Pb, Zn, and Cd, were employed to evaluate the effects of these passivators on the mobility and bioavailabity of Pb, Zn, and Cd in the railings. The results showed that the bioavailability and mobility of Cd was effectively reduced by the rape offal, grass straw, rice straw, lime and ammonium phosphate, and of Zn was effectively reduced by the rape offal, grass straw, rice straw and ammonium phosphate. While the bioavailability and mobility of Pb in the tailings was effectively reduced by the ammonium phosphate and rape offal. The exchangeable, carbonate bound of Cd and Zn among the Tessier＇s five chemical fractions were significantly correlated with Cd and Zn ex- tracted with DTPA method, while the carbonate bound of Pb was significantly correlated Pb extracted with DTPA method in the tailings. The concentration of bioavailable fractions of Cd, Pb, and Zn decreased, indicating that the rape offal and ammonium phosphate were the suitable in-situ passivator for lead and zinc mine tailings.