兖州煤田煤矸石中敏感性元素动态淋滤特征及环境效应评价

Dynamic Leaching Characteristics and Environmental Effects Assessment of Sensitive Elements in Coal Gangue of Yanzhou Coalfield

摘要:

煤矸石是煤炭资源开发过程中产生的大宗固体废弃物，其长期露天堆放会对环境造成一定的污染。为探究煤矸石在自然条件下降水淋滤过程中敏感性元素的淋出特征，选取山东省主要煤炭生产基地——兖州煤田某典型煤矿的煤矸石作为研究对象，模拟自然降雨条件下动态淋滤试验对煤矸石中的9种敏感性元素淋出特征进行了研究。结果表明：淋出液的pH值均偏碱性，介于9.3～9.8，且随着淋滤次数的增加逐渐增高并趋于稳定。F,As元素具有较强的淋出活性，其淋出率分别为2.60%，1.06%，且全部时间段的淋出液浓度均超出了地下水质量标准Ⅳ类水限值。Cd，Cr，Cu，Hg，Ni，Pb，Zn元素的淋出率均低于0.05%，反映了相对较弱的淋出活性，其各时间段的淋出液浓度均满足地下水质量标准Ⅲ类水的要求。9种敏感性指标均呈现有间歇性快速释放规律，且随淋滤时间的延长，各元素在淋滤后期逐步稳定慢速释放。大量露天堆放以及直接充填于采煤塌陷区内的煤矸石对周边水环境的长期污染效应不容忽视。

Abstract:

Coal gangue is a large scale solid waste generated during the development of coal resources. Its long term openair stacking will cause certain pollution to the environment. In order to explore the leaching characteristics of sensible elements in the leaching process of coal gangue under natural conditions, choosing coal gangue of a typical coal mine in Yanzhou coalfield——a major coal production base in Shandong Province as the research object, dynamic leaching experiment under natural rainfall conditions. has been simulated. The leaching characteristics of nine sensitive elements in coal gangue have been studied. It is showed that pH value of the leachate is alkaline ranging from 9.3 to 9.8, and gradually increases and tends to stabilize as the number of leaching times increases. The element of F and As have strong leaching activity, and their leaching rates are 2.60% and 1.06% respectively. The concentration of leaching solution in all period exceeds the groundwater quality standard class Ⅳ water limit. The leaching rates of Cd, Cr, Cu, Hg, Ni, Pb and Zn are all lower than 0.05%, which reflect the relatively weak leaching activity. The concentration of leaching solution in each period meets the groundwater quality standard Ⅲ water requirements. Nine sensitive indicators show intermittent rapid release. Accompanying with the prolongation of leaching time, each element will be gradually stabilized and slowly released in the late stage of leaching. The long term pollution effects on the surrounding water environment due to a large number of openair stacking and coal gangue directly filled in the coal mining subsidence area cannot be ignored.