Release Behavior of Arsenic during Pyrolysis of Two Chinese Coal Gangues

Release behaviors of arsenic (As) during pyrolysis of two Chinese coal gangues were studied in this report. The pyrolysis experiments were carried out in a temperature programmed tube furnace under N2 atmosphere with different temperature (200-1200 ºC), residence time (0-50 min), heating rate (10-50 ºC min-1) and N2 gas flow rate (100-500 cm3 min-1). The experiment results, under different pyrolysis conditions, indicate that the release ratio of As increases with increasing temperature, as well as residence time during pyrolysis of coal gangues. Besides that, higher heating rate during pyrolysis of coal gangues can stimulate the As release from coal gangue to some extent. The release ratio of As increases to a maximum and then decreases when the N2 gas flow rate is increased. The results imply that different modes of ocurrence of As exist in two coal gangues. The As release has positive relation with the volatile matter release. As is more easily released than coal gangue matrix during coal gangue pyrolysis.

本报告针对两种中国煤矸石热解过程中砷（arsenic, As）的释放行为开展了系统研究。热解实验于氮气（N2）氛围下的程序升温管式炉中进行，考察的实验参数涵盖热解温度（200~1200 ℃）、停留时间（0~50 min）、升温速率（10~50 ℃·min⁻¹）以及氮气流量（100~500 cm³·min⁻¹）。不同热解条件下的实验结果表明，在煤矸石热解过程中，砷的释放率随热解温度与停留时间的升高而提升。此外，较高的热解升温速率可在一定程度上促进砷从煤矸石中释放。当氮气流量升高时，砷的释放率先升至峰值后逐步下降。上述结果暗示，两种煤矸石中砷的赋存形态存在差异。砷的释放与挥发分释放呈正相关关系，且在煤矸石热解过程中，砷比煤矸石基体更易于析出。