Evaluation of mercury associations in two coals of different rank using physical separation procedures

Mercury is considered to be a toxic metal of major concern, while coal combustion is recognized as one of the main anthropogenic sources of this element. Various processes have been investigated for mercury control in coal-fired utilities. However, until now, no cost-effective or efficient technology has been established for the removal of mercury emissions from coal combustion. For the development of such technologies a deep knowledge of the mode of occurrence and association of mercury compounds in different coals is necessary. Size fractionation, density separation, and oil agglomeration procedures were evaluated in this work not only to assess their efficiency as cleaning methods in mercury removal, but also to determine the associations of mercury with mineral/organic phases. Although the efficiency for mercury removal was found to be generally low, the results obtained provided valuable information for identifying the modes of occurrence of mercury in coal.