In 2001, a report from the Department of Health in Manila documented a yearly release of 140 tons of mercury from two small scale mining communities on the island of Mindanao. In 2007, further investigations by GEUS discovered mercury releases from yet two other small-scale mining communities of Mindanao in the order of 5 tons per year. Extrapolated to all small-scale mining communities of the Philippines, these figures suggest, that 200 to 500 tons of mercury is being released annually into the environment.
The reason for this massive release from small-scale mining, is that mercury is added to gold ore in the grinding process. Prolonged grinding of mercury produces mercury flour which cannot coalesce and thus cannot be recovered by the miners, and it ends up in the tailing dams. Sampling of tailings showed mercury contents up to 420 gram per ton. Large amounts of gold are trapped in the mercury flour and this gold is unrecoverable, a major loss since gold contents up to 16 gram per ton have been measured in the tailings.
Most of the released mercury throughout the Philippines is hosted in the gold miners' tailing dams that unfortunately are not properly secured. With time, the contents of these leak into the sea, where mercury will pervade the mangrove swamps that fringe the Philippines. These swamps serve as hatching grounds for fish and shellfish, the main source of protein for the Philippine population.
How can mercury and gold be extracted from the tailing dams?
If this process is successful, such State Battery plants have the potential to clean tailing dams of their mercury content throughout the Philippines. The whole operation will probably be cost neutral or it may even create a substantial profit from the gold that can be recovered along with the mercury.
In September 2010 tests were carried out during which a spiked tailing with 2700 ppm mercury was passed through a State Battery After two runs the mercury content was down to 12 ppm.
StakeholdersProject support: Sumitomo Foundation in Japan and GEUS.Project period: 1st December 2009 to 30th November 2011.Partners: Metals Industry Research and Development Centre, Philippines; Department of Geology, University of the Philippines; Department of Science and Technology, Manila and Japan Atomic Energy Agency, Tokai.
References GEUS report 2011/127: Cleaning mercury polluted mine tailings in the Phillippines (pdf-file ~4mb) GEUS report 2007/35: Training of Small Scale Miners - PhilippinesVidenskab.dk: Gigantisk kviksølvkatastrofe truer Filippinerne
Contact:Peter W. U. AppelSenior research scientistE-mail: email@example.comTelephone: +45 3814 2214