The Effect of Mercury Occurrence on Mercury Rejection During Coal Preparation

Coal preparation is a possible method to reject mercury from coal prior to coal combustion. To evaluate this approach, two coal samples were collected from the Laoshidan coal preparation plant in Neimenggu Province and the Tangshan coal preparation plant in Hebei Province, China for this study. Although energy recovery and ash reduction of the two samples were similar at a heavy medium separation of 1.80 specific gravity, there were distinguished differences between the two samples on sulfur and mercury reductions. Sequential extraction tests were used to analyze the mode of mercury occurrence and a polarizing reflection microscope was used to investigate the size of mercuride indirectly. The results indicate that the mode of mercury occurrence and the size of mercuride are important factors to reject mercury from coal by coal preparation.