WorldWide Drilling Resource

51 WorldWide Drilling Resource ® FEBRUARY 2015 Innovations in Mine Remediation Compiled by Amy White, Associate Editor WorldWide Drilling Resource ® Innovations in mine remediation are not just about technology; they are also driven by the needs of society. Over the last 15 years, mine site reha- bilitation has been integrated into the early planning process, even preceed- ing the start of operat ions. From a technical and financial perspective, rehabilitation management is an ongoing consideration throughout a mine’s life. When a deposit’s resources are depleted or no longer economically feasible, the mine ceases operations. At this point, the final stage of the site begins - rehabilitation. The objective is to remove or neutralize contaminants so the mine can begin a new life in a nonmining capacity. The following innovations demon- strate the ingenuity of mining rehabili- tation as the industry strives for more efficient, sustainable practices by con- tinually revisiting and renewing meth- ods and concepts. Biodegradable explosives - The residue from explosives contributes to mine site pollution. To combat this prob- lem, strains of the bacillus subtilis GN bacterium are used because they can decompose explosives in only a few days. Constructed wetlands - Wetlands can remove metals from mine site waste liquid and neutralize its acidity. Since these ecosystems are self-regulating, they could represent a long-term solu- tion to acid mine drainage. Reuse of mine tailings - Some companies use tailings (waste derived from mining) to treat contaminated soil. Tailings act as an oxygen barrier, and stem the flow of contaminated drainage water by sequestering polluted sediments. Neutralization of tailings - To reuse tailings, they must be stabilized. Tailings can be mixed with lime, ashes, wood shavings, cement, or other types of mate- rials to make a paste which can serve as a waterproof barrier or backfill. Geotextile separators - Geotextiles are films composed of a screen made of synthetic material. They create a physical barrier between the ground and materials stored in,or used to con- struct a facility. They are particularly useful for ore storage areas at mine sites. The barrier allows water to flow through, but stops fine particles in the underlying natural environment from entering the storage area. Geotextiles also prevent clogging in drains and Rehabilitated bauxite mine. Photo courtesy of chalieco.com drainage systems, and can therefore be used to protect mine tunnels. Solar panels for tailings sites - Mine tailings can cover considerable amounts of land; are difficult to rehabil- itate; and can quickly become aban- doned environmentally. Companies have been putting these sites to good use by developing solar farms on them. Chevron developed a 1-megawatt concentrating photovoltaic (CPV) solar facility at the molybdenum mine in Questa, New Mexico. About 175 solar panels are installed on 20 acres, making it one of the largest CPV instal- lations in the U.S.