广西茶山锑矿尾砂中微量元素的淋滤实验研究

采用干湿交替和完全浸没的方法,运用柱淋滤实验研究了广西南丹地区茶山锑矿选矿尾砂中微量元素的淋滤行为,淋滤液采用了模拟酸雨(pH 4.0～4.4)和河水(pH 8.0).结果表明,尾矿砂具有一定的酸中和能力,即使用pH 4.0～4.4的酸性溶液淋滤,产生的淋滤液也是偏碱性的,pH基本在7.2～8.0之间.与As和Pb相比,Sb更容易从尾矿砂中淋滤出来;干湿交替条件下Sb的淋出明显高于完全浸没条件,As更容易在完全浸没条件下淋出,且浸没间隔时间越长淋出浓度越高,间隔时间为5 d和10 d时As的淋出浓度比1 d和2 d时高出1～2倍;Mn和Zn具有相似的特点,它们受pH的影响较大,在模拟酸雨淋滤的淋出浓度明显高于河水淋滤,而干湿交替条件和完全浸没条件以及间隔时间对它们的淋出影响较小;Sr的淋出率较高,基本没有受到本实验中淋滤液和干湿交替条件以及完全浸没条件的影响;Pb基本没有淋出;尾矿砂内部的碱性环境和干湿交替条件是控制重金属锑淋滤的主要机制.

Leaching Experiments on the Release of Trace Elements from Tailings of Chashan Antimony Mine, Guangxi, China

The leaching of trace elements from tailings of an antimony mine in Guangxi Autonomous Region, China, was investigated through column leaching under wet-dry cycling and complete immersion conditions. Simulated acid rain (pH 4.0-4.4) and river water (pH 8.0) were used as the leaching solution. No matter the simulated acid rain or river water was used, the leachate always showed a slightly alkaline pH between 7.2 and 8.0, suggesting an acid neutralization capacity of the tailing. Compared to As and Pb, Sb was leached out to a much higher extent in this circumstance. Furthermore, Sb release was largely enhanced in wet-dry cycle compared to the complete immersion condition. In contrast, As was leached more readily in the complete immersion condition, and the longer the tailings were immersed in water, the higher the As concentration in the leachate. The leachate on day 5 and day 10 showed 1-2 times higher As concentration as compared with the leachate on day 1 and day 2. The leaching of Mn and Zn by simulated acid rain was much stronger than that by river water, and the release of Mn and Zn was more significantly affected by pH than by O₂ (i. e. the difference between the wet-dry cycle and complete immersion condition). Sr showed a high release rate that was not affected by leaching solution or air-exposure condition. Basically, Pb showed a very low leaching potential. In general, an alkaline circumstance combined with wet-dry cycle forms the favorable condition for the release of Sb in the tailings.