煤矸石中氮溶出的动态淋滤实验

Continuous leaching experiments of nitrogen from coal gangue

为了探讨煤矸石中所含铵伊利石矿物和吸附的氮在风化过程中对周围环境产生的氮污染潜力,利用连续动态淋滤实验方法,对山西长治南寨煤矿和河南焦作朱村煤矿矸石进行淋滤实验,测定了滤出液中总氮、铵态氮、硝态氮和亚硝态氮的质量浓度变化,分析了煤矸石中各种氮的溶出行为。结果表明:煤矸石矿物表面吸附的硝态氮比较容易被水所溶出,并且随着淋滤时间的延长,滤液中硝态氮的含量迅速降低;煤矸石铵伊利石矿物晶格中固定氮的溶出是一个持续缓慢的过程,其大量溶出滞后于硝态氮的溶出;不管是酸性水或中性水,其滤液均呈偏碱性,这与煤矸石中NH4+的缓冲作用有关。实验结果揭示煤矿区矸石堆中的氮在风化过程中,会被雨水淋溶出来进入周围土壤或地表水体,造成周围环境氮的富集。

In order to explore the potential pollution of nitrogen leached from coal gangue which contains ammonium illite and absorbed nitrogen during weathering,the continuous leaching experiments about the coal gangues,collected from Changzhi Nanzhai Coal Mine of Shanxi Province and Jiaozuo Zhucun Coal Mine of Henan Province,were conducted,and the releasing behavior of nitrogen from coal gangue was discussed based on the measurement of various forms of nitrogen in the leached solutions,such as total nitrogen,NH＋4-N,NO3-N and NO2-N.The results show that NO3-N absorbed on the surface of coal gangue minerals is easy to be leached out by water and its concentration in leached solution is decreased rapidly with leaching time,and the release of fixed nitrogen in ammonium illite of coal gangue is slow and its massive release lags behind NO3-N,and the leaching solution is alkalescent whether leached by acid or neutral water,which may be related to the cushion of NH＋4 in ammonium illite.The experiments show that the nitrogen in the coal gangue pile in coal mine district may be leached out by rain and enter to the surrounded soil and surface water,which may cause the accumulation of nitrogen in environment.