西南喀斯特地区典型矿渣中砷、锑的赋存形态及其潜在风险评价

The speciation and potential risk assessment of arsenic and antimony in typical mine tailings of Karst area,Southwest China

针对西南喀斯特地区典型矿渣中砷、锑的赋存形态及其潜在风险的问题,采用Shiowatana连续提取法提取矿渣中的砷(As)、锑(Sb),分析并揭示As、Sb的赋存特征;结合矿渣的基本理化性质和矿物组成特征,讨论矿渣堆中As、Sb的活动性及其关键影响因素;采用风险评价编码法(RAC)对矿渣中As、Sb的潜在生态风险进行相关评价.结果表明:矿渣中的As主要以铁铝结合态和残渣态的形式赋存;Sb主要以残渣态的形式赋存.As比Sb具有更高比例的铁铝结合态,而Sb比As具有更高比例的碳酸盐结合态.弱酸至近中性矿渣中,Sb的活动性强于As;酸性矿渣中,As的活动性强于Sb.矿渣中As、Sb的潜在风险以中-低风险为主,个别为高和极高风险.

Shiowatana sequential extraction method was used to extract arsenic(As)and antimony(Sb)from mine tailings aiming at the chemical speciation and potential risks of As and Sb in typical tailings in karst area of Southwest China,and the speciation characteristics of As and Sb were analyzed and revealed. This study discussed the availability and key influencing factors of As and Sb in mine tailings,based on the physical,chemical properties and mineralogical characteristics of tailings. The ecological risk of As and Sb was evaluated by risk assessment coding method(RAC). The results showed that As mainly associated with Fe-and Al-bound and residue fraction;Sb mainly associated with residue speciation. Comparatively,the amount of As extracted in Fe-and Al-bound fraction was more than that of Sb,and the amount of Sb extracted in carbonate-bound fraction was higher than that of As. In the weakly acidic to neutral tailings environment,the mobility of Sb was greater than that of As;In the acidic environment,the mobility of As was stronger than that of Sb. In general,the potential risks of As and Sb in mine tailings were mainly medium to low risks,except for individual high and extremely high risks.