铅锌尾矿中重金属在模拟酸雨淋溶下的浸出规律

重金属尾矿污染是世界性难题,污染水体、大气和土壤,对周边的生态环境和人体健康造成严重危害。在我国酸雨范围大且酸雨问题比较严重的背景下,探讨酸雨淋溶下尾矿中重金属的浸出规律将有利于加强我国重金属尾矿的污染控制和管理。采用湖南桃林铅锌尾矿库中的尾矿模拟酸雨条件进行淋溶实验,研究发现重金属Pb、Zn、Cu、Mn含量分别为1252.5,849.4,363.1,280.0mg/kg。其中,Pb、Zn主要以残渣态存在,分别占69.7%和53.8%;Cu主要以有机结合态存在,占67.0%;Mn主要以铁锰氧化态、有机结合态和残渣态存在,共占90.0%。在静态淋溶实验中,固液比越大、模拟酸雨pH值越小,重金属的浸出浓度越大。在动态淋溶实验中,Zn、Mn浸出浓度随时间呈现减小趋势,而Pb和Cu浸出浓度随时间先增大,后减小。

THE LEACHING PRINCIPLES OF HEAVY METALS IN LEAD AND ZINC TAILINGS IN SIMULATION ACID RAIN

Mine tailings pollution is a worldwide problem,causing pollution in water,air and soil,and eventually resulting in serious hazard to the surrounding ecological environment and human health.Under the condition of acid rain leaching,the migration of heavy metals in lead and zinc mine tailings will be greatly enhanced,thus cause greater contamination.In this paper,Taolin mine tailings are used to investigate the leaching principles of the tailing samples in simulation acid rain,which will contribute to strengthen the control and management of mine tailings.The conclusions are as follows: the tailings contained high concentrations of heavy metals(concentrations of Pb,Zn,Cu and Mn are 1252.5,849.4,363.1 and 280.0 mg / kg,respectively),which has serious potential hazard.Pb and Zn are mainly present in residual fraction,accounting for 69.7% and 53.8% respectively;while the fraction bound to organic matter is the main combination pattern of Cu,accounting for 67.0%;and the fractions bound to Fe-Mn oxides,organic matter and the residual are the main combination patterns of Mn,accounting for 90.0%.In static leaching experiments,greater solid-liquid ratio and smaller acid rain pH contribute to higher leaching concentrations of heavy metals.In the dynamic leaching experiments,the leaching concentrations of Zn and Mn decreased along with time,while the leaching concentrations of Pb and Cu increase at the beginning and then decrease.