铵伊利石质矸石氮的溶出实验

Leaching experiments on nitrogen release from ammonium illite gangue

利用铵伊利石含量较高的泥质矸石,采用静态浸泡淋滤实验,通过对淋滤液中不同形态氮的测定,探讨了铵伊利石矿物氮的溶出机理和行为.研究发现,铵伊利石矿物中的NH4+易于被水溶出.在初始pH值为中性和酸性的淋滤体系中,NH4+具有相似的溶出行为.NH4+在碱性条件下比在中性和酸性条件下更易溶出.不管淋滤液初始酸碱度如何,随时间增加,淋滤液均趋于中性—弱碱性,说明铵伊利石矿物对酸碱具有缓冲作用.铵氮是淋滤液中氮的主要形式,硝态氮和亚硝态氮含量则很少.不同形态氮之间存在转化关系,随时间的增长,铵态氮逐渐向硝态氮转化,碱性条件可加速转化过程.模拟实验与实际水体的检测表明:铵伊利石矸石在长期的风化淋滤过程中,其溶出的NH4+对矸石堆周围水体和土壤中氮的富集和污染可能有潜在的贡献.

The release mechanism of nitrogen from ammonium iltite was discussed through the analysis of different forms of nitrogen in leaching solution based on the static soak-leaching experiments of ammonium illite-bearing gangue. It is found that NH4 is easy to be leached out from ammonium illite. It possesses the same release performance in initial neutral and acid solution, but easier to be leached out in alkaline solution. No matter what the initial pH value is, the pH value of leaching solution remains neutral to alkalescent with time increasing, which is suggested to be related to the cushioning action of Illite-NH4^＋. NH4^＋ -N is the main form of nitrogen in the leaching solution, but NO3^- -N and NO2^- -N are lower in concentration. The different forms of nitrogen can be transformed to each other, generally from NH4^＋ -N to NO3^- -N and this transformation can be accelerated in alkaline condition. The experiments imply that NH4^＋ leached out in the weathering of ammonium illite gangue can potentially contribute to the accumulation and pollution of nitrogen on the surface water and soil around coal mine waste gangue.