吴家坪煤中砷在亚临界水条件下的行为

在煤的燃烧和气化过程中，有毒微量元素的释放对人体健康和环境造成了危害。如何有效控制这些有害元素的排放已经越来越引起研究的关注。微量有害元素主要为砷、汞、铅、镉、锰等。尽管在煤中的含量很低，但是煤的大量使用，其总排放量还是相当大的，由此引起的污染问题也引起重视。煤的燃前脱除有害微量元素是一种有效控制其排放的方法。目前，煤的燃前脱除微量有害元素的方法很多，例如热解、水热处理可部分脱除煤中的微量元素，但都有局限性。

Transformation behavior of arsenic in Wujiaping coal during sub-critical water treatment

The trace elements emission could result in harmness to the environment and human health during coal combustion. The removal of trace elements before coal combustion is an effective method. The transformation and removal behavior of arsenic in Wujiaping (WJP) coal during sub-critical water treatment was studied in a semi-continuous apparatus. Effects of temperature, pressure, residence time and water flow rate on the arsenic removal were discussed. The occurrence modes of arsenic in WJP raw coal and residuals treated by sub-critical water were also studied by float-sink experiments and sequential chemical extractions. The results show that with the increasing of temperature, pressure, residence time and water flow rate, the arsenic removal in WJP coal also increases; and at the condition of 380 ℃, 15 MPa, 60 min and water flow rate of 0.58 L/h, the arsenic removal is about 62%. Arsenic in WJP coal mainly is associated with sulfates & mono sulfides, disulfide & some organic matters and “insoluble forms”. Sub-critical water treatment can decrease all these arsenic forms in coal and transfer them into the volatile form.