Mining companies can reduce costs and increase efficiency by managing mine closures, rather than handing over the process to government agencies, a mining hydrologist with Schlumberger Water Services said during a presentation to the Northern Nevada section of the Society for mining, Metallurgy and Exploration.
Mining hydrologist Geoff Beale says mine operators also should use the “mine to close” approach—a more sustainable approach—when planning their initial and expanded site layoffs to reduce the chance of dealing with continued mining pollution issues, reported MineWeb.
Mine closure practices and science cover four general categories: open pit mines in arid environments, open pit mines in temperate/humid environments, underground mines in elevated terrain and underground mines in lowland terrain, reported MineWeb. Underground mines in low terrain are the easiest closures to manage, Beale says.
Studies are important for developing broad methods for closing a mine and for pinpointing potential issues at the early stage of the mining cycle, Beale says. However, the final years of mine operations, when more monitoring data is available, provides better understanding of actual closure conditions, Beale says.
Pit backfilling, rapid flooding to form a pit lake, the potential for acid generation, achieving acceptable post-mining water quality and managing slope stability are some of the issues operators must contend with during a close, Beale says. Managing acid mine drainage is often a major obstacle for a mining closure.
Wastewater from acid mine drainage could help remove much of the naturally occurring radioactivity in fracking wastewater when blended together, according to a Duke University-led study published in January 2014 in the journal Environmental Science & Technology.
While fracking wastewater and acid mine drainage each pose environmental risks, blending them can bind some fracking contaminants into solids that can then be removed before the water is discharged back into waterways. Blending fracking wastewater with acid mine drainage also could help reduce the depletion of local freshwater resources by giving drillers a source of usable recycled water for the hydraulic fracturing process.
Photo of open pit mine from Flickr user Uncle Kick Kick, CC 2.0