Upon exposure to air, the newly exposed surfaces of mined rock begin to weather and oxidize. Because the nature of these oxidation products and potential associated water quality impacts vary for different rock types (including wide variation at a single deposit), Kinross conducts extensive studies to characterize the materials that will be exposed to weathering by our activities. Mining operations are developed with consideration for the expected geochemical transformations and to design and operate each of our mines to avoid or minimize impacts. Mineral waste management plans are routinely reviewed and updated to ensure that facilities are both physically and chemically stable. Regular monitoring and inspection are required to verify that design expectations are being met.
We continue to support and participate in the International Network for Acid Prevention (INAP), an industry group founded in 1998 that supports the development of technical guidance and standards for the prevention and control of acid mine drainage. INAP’s research and guidance documents are available through its website: www.inap.com.au
Tailings are deposited in storage facilities designed, built, operated and closed to meet regulatory and engineering safety and environmental standards. Tailings management programs are in place at each of our sites to continuously monitor the stability of these facilities, including detailed water balance accounting to assure sufficient storage capacity and a periodic review of operational procedures. At mine closure, tailings dams are decommissioned and reclaimed to increase their long-term stability and ensure that they become a part of the post-mine land use.
In addition to requiring an annual inspection of each Kinross tailings facility by a geotechnical engineer, we apply an additional level of oversight, led by an external geotechnical expert who reports to senior management at Kinross. Third-party technical reviews were performed on tailings storage facilities (TSF) at Paracatu, Tasiast, Chirano and Kettle River-Buckhorn over the two-year period.
At Paracatu, the new Eustaquio tailings storage facility became operational in March 2012. In January 2013, we opened a new tailings facility TSF3 at Tasiast to replace TSF2, which was constructed prior to Kinross’ acquisition of the mine and was not performing consistently with Kinross’ standards. We continue to operate dewatering wells at TSF2 to recover water and seepage.
The Kupol tailings facility design includes, below the dam, a sump to capture any run-off from the dam face or seepage beneath the dam. Beginning in late 2010, monitoring detected seepage below the dam, which was captured in the sump and returned to the dam. A number of measures and improvements were immediately put in place and have been previously reported by Kinross. While seepage has decreased, it will continue to exist until refreezing of the permafrost occurs. Until then, and as carried out throughout 2012 and 2013, seepage will continue to be safely captured and recovered and pumped back into the tailings storage facilities.
Disposing of By-Products
One of the by-products of gold recovery and air emissions controls at La Coipa is elemental mercury, which is naturally present in the ore and is captured as part of ore processing. Following the U.S. ban on the export of mercury in 2012, Kinross began selling its mercury by-product from La Coipa to an Australian-based manufacturer of dental amalgam. Elsewhere, the minor amounts of mercury by-product collected from air emissions controls by other Kinross operations are disposed of as a hazardous waste.