模拟风化过程硫铁矿尾矿的产酸性及污染物的释放行为

Acid generation behavior of pyrite tailing and characteristic of pollutant release during simulated weathering process

以广东某硫铁矿为研究对象,静态评价了3个尾矿的产酸潜力,结合40周左右氧化淋滤风化实验,揭示出硫铁矿尾矿在风化过程中的地球化学行为.静态结果显示其中两个尾矿具有强产酸潜力,一个为产酸不确定.动态氧化淋滤实验结果表明:(1)受CaCO3的缓冲作用控制,产酸潜力尾矿淋滤液pH值从初始7.2缓慢阶梯式下降到5.2,并呈现酸化趋势;(2)pH 6.5左右氧化还原电位Eh出现拐点,从负值转变为正值,体系氧化性增强;(3)可溶物在氧化淋滤初期表现出较强的释放能力,pH值降到6.5、Eh转向正值后急剧减弱并趋于平缓.风化产物硫酸钙及铁氧化物对金属离子的吸附与共沉淀作用可能是导致含金属离子固溶物溶解释放减弱的主要原因.

The potential of acid generation for three pyrite tailings from Yunfu pyrite area was evaluated by static test. The geochemical behaviors of these tailings during the weathering process were investigated by 30—40 cycles humidity cell tests. Static tests indicated that two of the samples have strong potential of acid production, and the other sample was uncertain. The humidity cell tests showed that, first of all, leachates pH of the samples with acid generation potential slowly decreased from 7.2 to 5.2 due to the buffer function of CaCO3 and displayed the trend of becoming acidic. Second, Eh turned from negative to positive at pH 6.5 and system oxidation potential gradually increased. Third, release of soluble minerals was rapid during initial leaching and slowed down rapidly to become steadly when the pH dropped to 6.5 and Eh turned to positive. Adsorption and co-precipitation on weathering products were probably the main factors controlling metals release.