煤矸石动态循环淋溶液的特性

Characteristics of dynamic cyclic percolation solution from coal gangue

为评价煤矸石回填塌陷区后对水体影响,采用自行设计的新型淋溶装置进行连续168 h的淋溶实验。通过采用电感耦合等离子体质谱仪(ICP-MS)和pH测试仪等相关分析仪器研究了煤矸石中重金属在淋溶过程中的溶出规律,并对淋溶液的COD、BOD、TON、NH3-N和pH值进行测试分析。结果显示,淋溶反应时间1~24 h时,淋溶液的COD和BOD分别从28.001 1和4.400 0 mg·L^(-1)升至36.437 29和6.191 525 mg·L^(-1),超过地表水环境质量五类标准限值。在24~168 h的淋溶时间内,TON的值先降低至2.983 4 mg·L^(-1)而后升高至8.494 6 mg·L^(-1),而在72~168 h内,淋溶液中TON呈线性趋势大幅度增加。铬元素溶出浓度的峰值主要发生在淋溶初期;铅离子在24~72 h淋溶时间内,析出速度明显加快;锌离子溶解初期为慢速释放,中期为快速释放,末期为慢速释放;铜离子在淋溶反应开始时溶出较少,而随着淋溶反应时间的延长,溶出速度增大。

Cyclic leaching experiments with a new leaching device were carried out for 168 hours to evaluate the leaching characteristics of coal gangue. An inductively coupled plasma mass spectrometer（ ICP-MS） and a pH tester were employed for the testing and analysis. The following were determined,namely,the leaching rule of heavy metal of coal gangue in the leachate,the changes of the pH of the tested solution,and the values of COD,BOD,TON,and NH_3-N in the leaching solution. The research results showed that the values for COD and BOD increased from 28. 001 1 and 4. 400 0 mg·L^-1to 36. 437 29 and 6. 191 525 mg·L^-1,respectively,within 1 to24 hours. In the leaching process,naphthalene,phenanthrene,fluorene,and the other aromatic compounds in the coal dissolved in the water,which led to the COD and BOD values increasing rapidly and exceeding class Ⅴof the environmental quality standard for surface water. The value for TON first decreased and then increased from 2. 983 4 mg·L^-1to 8. 494 6 mg·L^-1within 24 to 168 hours. The TON in the leaching solution increased significantly in a linear trend. The peak value for Cr leaching was observed mainly in the initial stage of leaching,and the leaching rate of Pb noticeably accelerated within 24 to 72 hours. The releasing velocity of the zinc ions was different at the different stages of leaching. The dissolution rate of the copper ions in the leaching reaction was lower in the beginning,but this rate increased with the increase of the leaching reaction time.