Evaluation of coal combustion by-product mercury re-release potential

FUEL 90

Loreal V. Heebink and David J. Hassett. Energy & Environmental Research Center, University of North Dakota, 15 North 23rd Street, Grand Forks, ND 58203
As control technologies reduce the air emissions of mercury from power plants, the amount of mercury in coal combustion by-products (CCBs) will likely increase. This poses a critical question: Will the mercury removed from the flue gas really be removed from the environment or will it be relocated and released later? Researchers at the Energy & Environmental Research Center have investigated the potential for the rerelease of mercury from CCBs under a variety of conditions in an effort to address various ash management scenarios. Work is ongoing under four conditions, including leaching, long-term ambient-temperature vapor release, microbiologically mediated vapor release, and high-temperature thermal release up to 700 °C. Results to date indicate little to no rerelease of mercury through leaching or through ambient-temperature vapor transport. Current investigations are focused on CCBs resulting from the use of mercury control technologies to determine whether the potential for mercury release will increase.