Pre-combustion removal possibility of hazardous trace elements from Indian high-ash coal by coal preparation technologies

摘要

Many of the potentially hazardous air pollutants listed in the 1990 Clean Air Act are elements commonly found in trace amounts in coal. When coal is burned, these elements release into the environment. An option for controlling the release of these elements into the atmosphere is to remove them before combustion. Conventional physical coal cleaning processes are effective in reducing the concentration of many of these trace elements in coal. In addition, advanced cleaning processes directed toward reduction of various elements may perform better than conventional processes. Therefore, current research focuses on the advanced coal cleaning technology which is directed toward reduction of mineral matter and various toxics elements as well. Results of recent studies indicate that the degree to which a specific trace element can be reduced by coal cleaning depends on its distribution in the coal. To quantify the capabilities of a gravity-based coal cleaning process for removing these hazardous air pollutants, a detail study was conducted on a coal sample collected from one mine of Talcher area. Careful analysis of the experimental data indicates that most of the trace elements of greatest environmental concern are strongly associated with the organic matter of the investigated coal, thus during beneficiation these elements are concentrated in the clean coal fraction. Therefore, it makes the situation more complex and the expected pre-combustion removal of these trace elements seems to be not possible for the high-ash non-coking coals of Talcher coal field.