Coal combustion residues useful in reclaiming abandoned mine lands
Abandoned mine lands (AMLs) pose hazards to the surrounding environment and habitat. Reclaiming AMLs improves the ecosystems present and removes potential safety hazards to humans in these regions. Researchers in Ohio State's Combustion Products Program have identified the use of flue gas desulfurization (FGD) materials to reclaim abandoned mine lands as an "effective approach to reclaim AMLs."
Tarunjit Butalia, associate research professor and Director of the CCP Program, and collaborators Chin-Min Cheng and Mehedy Amin conducted a three-phase study that investigated the feasibility of using high-volume FGD materials such as stabilized sulfite-rich FGD (sFGD) material (a mixture of lime, fly ash, and FGD filter cake) and sulfate-rich FGD gypsum to reclaim an AML site located near a coal-fueled power plant.
The trio's findings, Sustainable Use of FGD Structural Fills in Mine Reclamation: Geotechnical Properties and Environmental Response, were recently featured in ASH at work. In the article published by the American Coal Ash Association, Butalia, Cheng and Amin summarize their reclamation efforts as well as the environmental responses they observed at the Conesville coal-fired plant site in eastern Ohio.
Site preparation and the introduction of the initial batch of sulfite-rich FGD took place in early 2012 while additional sFGD and FGD gypsum were added in August of 2013. Backfilling of the site's highwalls, the face of the site yet to be excavated, took place in December of the following year.
Since 2015, the team observed environmental changes, and, in particular, tested for adverse effects to the surrounding groundwater. After five years of site monitoring since the reclamation was completed, Butalia and his team found no evidence to suggest that the FGD structural fill had any significant impact on aquifers underlying the Conesville demonstration site.
Butalia described the use of these materials to remediate the safety and environmental challenges posed by these un-reclaimed sites as a win-win situation and is confident about the future use of these methods. "Coal by-products are now part of the solution – in bringing these un-reclaimed lands back to productive use," he said.