材料期刊网

以广西某典型锡尾矿为对象，重点研究不同模拟酸雨pH值(3.0，4.5，6.0)条件下尾矿中特征重金属As、Zn、Pb的释放规律。结果表明：As、Zn、Pb累积释放量、淋溶强度及淋出液电导率与模拟酸雨pH值呈负相关，而淋出液pH值与模拟酸雨pH值呈正相关。在尾矿淋溶过程中，淋出液的pH值呈先急速上升后快速下降最后缓慢增长的趋势，电导率保持持续增长；重金属As、Zn、Pb的释放过程分为3个阶段，且淋溶强度由大到小的顺序依次为Pb、Zn、As。XRD分析表明：淋溶后尾矿中主要矿物石英、方解石及磷铁铝矿衍射峰的强度明显减弱，且模拟酸雨pH值越低，强度减弱越明显。SEM-EDS分析发现，尾矿经淋溶后表面变得不平整，出现大量孔洞和硅酸钙颗粒物，随着淋溶时间延长，Fe、S、As、Zn、Pb的含量明显减少。

Leaching experiments of a Guangxi typical tin tailings under simulated acid rain (pH=3, 4.5, 6.0) were carried out to investigate the release law of As, Zn and Pb. The results indicate that the pH of leaching liquid is positively correlated to the pH of simulated acid rain, while the conductivities, the accumulated leaching liquid concentrations of As, Zn and Pb and leaching intensity are negative correlated. The pH of leaching liquid increases at first, and then decreases frequently, and last it keeps increasing gradually. The conductivities keep steady growth and the releasing characteristic of As, Zn and Pb is similar in the leaching process. It can be divided into three stages. The leaching intensity from big to small is Pb, Zn and As. The main difference with the XRD pattern of tailings decreases obviously in the relative height of peak of main mineral, such as quartz, calcite and paravauxite. The pH of the acid rain is lower, the decrease of the height is more significant. The results of SEM analysis show that the surface of leaching residue becomes rough which appears lots of holes and precipitation. The EDS analysis indicates that the precipitation adhered to the leaching residue surface is CaSiO 3 , and with time prolonging, the contents of Fe, S, As, Zn, Pb reduce significantly.