大宝山尾矿重金属形态及其潜在迁移能力分析

Analysis of chemical forms and potential mobility ability of heavy metals in tailings from Dabaoshan mine

以大宝山槽对坑尾矿库、新鲜尾矿排放口和铁龙尾矿库3个不同区域尾矿为研究对象,采用Dold七步分级化学提取法研究了4种重金属Cu、Pb、Zn、Mn的化学形态特征,并分析了其潜在迁移能力。结果表明,Cu、Pb在所有尾矿中以原生硫化态和残渣态为主;Zn在槽对坑尾矿和新鲜尾矿中以原生硫化态和残渣态为主,在铁龙尾矿中水溶态、可交换态、羟基氧化铁态、铁氧化态和有机态增多,5种形态所占百分比总和超过40%;Mn在槽对坑尾矿样品中以残渣态为主,在新鲜尾矿中以羟基铁氧化态、原生硫化态和残渣态为主,而在铁龙尾矿样品中以水溶态为主。在槽对坑和铁龙尾矿中,重金属的潜在迁移能力顺序为Mn>Zn>Cu>Pb,在新鲜尾矿中为Mn>Cu>Zn>Pb;不同采样点重金属潜在迁移能力顺序为:铁龙尾矿样品>新鲜尾矿样品>槽对坑尾矿样品。

The tailing samples investigated in this study were collected from Caoduikeng tailing reservoir,fresh tailing outlet port and Tielong tailing reservoir in Dabaoshan mine area.The chemical speciation characteristics of Cu,Pb,Zn and Mn contained in tailing samples were determined by 7-steps sequential extraction method improved by Dold B,and then the potential migration abilities of these heavy metals were evaluated.The results showed that primary sulfides and residual state were the main form of Cu and Pb for all the tailing samples.The dominating chemical forms of Zn in Cao duikeng tailings and fresh tailings were primary sulfides and residual state,and for Tielong tailings,Zn species of water-soluble fraction,exchangeable fraction,Fe（III） oxyhydroxides leach,Fe（III） oxides leach,organics fraction increased and their total proportion exceeded 40%.The residual state was the dominant form of Mn in Caoduikeng tailings,while for fresh tailings Mn species were found in the state of oxyhydroxides leach,the primary sulfides and the residues.And additionally water-soluble fraction of Mn species played the dominant roles in Tielong tailings.The mobility of these heavy metals in Caoduikeng tailings and Tielong tailings follows the order of MnZnCuPb,and in the fresh tailings the orders of their mobility was MnCuZnPb.The mobility of heavy metals for different areas follows the order：Tielong tailingsfresh tailings Caoduikeng tailings.