HTM铜矿尾矿库浅层剖面重金属赋存形态及污染特征

Chemical fractions and pollution characteristics of heavy metals in surface profile of HTM copper tailings pond

在HTM铜矿尾矿库不同位置进行剖面分层取样,取样深度200 cm,测定了不同深度层次尾矿的pH、重金属Cu、Zn、Cd全量及各化学形态含量;为了估算尾矿库表层污染物流失量,采用荷兰产大型取土器,以50 m×50 m网格法对尾矿库表层0-120 cm剖面间隔20 cm分层取样,测定尾矿中重金属Cu、Zn、Cd的全量。结果显示,各层尾矿pH值在3.01-7.79之间,表层0-40 cm pH最低,且随深度增加而升高;尾矿中Cu、Zn、Cd主要以相对稳定的有机结合态和残余态2种形式存在,0-60 cm尾矿中可交换态和碳酸盐结合态Cu、Zn、Cd含量较高。尾矿库浅层剖面可以划分为3个明显的层次：氧化层、胶结层和未氧化层,该尾矿库尾矿重金属的淋失主要发生在0-40 cm氧化层。据测定结果估算,尾矿库表层尾矿在闭库20年间持续释放的Cd为516.38 kg,Zn为42.24 t,S总量为762.75 t。研究结果为改进尾矿库现行治理措施与模式提供了依据。

Four 200 cm profiles in HTM copper mine tailings pond were dug for sampling and observation,the pH of the samples determined by pH meter,and the total content and the chemical fraction of Cu,Zn,and Cd were determined by ICP-OES. In order to estimate the total losses of contaminant from the surface layer of the tailings pond,tailing samples were taken using a geotome at every layer to 20 cm interval in the depth of 120 cm at 18 sampling points,and the total contents of Cu,Zn,and Cd were determined. Results show that the pH value of the tailings was from 3. 01 to 7. 79,the pH of the tailings in 0—40 cm was lower and the pH rose constantly with depth in 0—200 cm. Bound to organic matter and residual were the major chemical fractions of Cu,Zn and Cd in tailings,the contents of exchangeable and bound to carbonates were relatively high in 0—60 cm. The tailings profile could be divided to three different layers： oxidation layer,cement layer and non-oxidation layer,the main loss of heavy metals was from the surface leaching of 0—40 cm. The total losses of Cd,Zn and S that released from the surface layer of the tailings pond in the past 20 years were approximately 516. 38 kg,42. 24 t and 762. 75 t,respectively. The results can be used to improve the reclamation measures for similar tailings pond.