Remediation of mercury polluted tailings

In 2010 Peter Appel (Geological Survey of Denmark and Greenland) and Leoncio D. Na-Oy (Emerald Small Scale Miners Multi Purpose Cooperative) together with Yuichi Hatsukawa (Japan Atomic Energy Agency) were rewarded funding from the Sumitomo Foundation (Japan) for testing and improving a gadget (State battery) invented in Australia around 1850 for cleaning mercury pollution caused by small-scale gold mining. The improved version was termed Peter Plates. The tests were carried out in Benguet, Philippines in 2010 and 2011. The successful results were published in Appel, P.W.U., Na-Oy, L. D., Hatsukawa, Y., Osawa, T., Kystol, J. & Sørensen, L.L. 2011: Cleaning mercury polluted mine tailings in the Philippines. Danmarks og Grønlands. Geol. Unders. Rap. 2011/127, 39 pp.

In 2014 Danish Ministry of Environment rewarded Elplatek a grant to determine possibilities to extract mercury flour from tailings from small-scale gold mining. Danish Technical University Department of Metallurgy and Appelglobal were partners. Two sessions of testing were carried out in Northern Nicaragua. In 2015 follow up financing was rewarded from the Danish Ministry of Environment. The project was terminated October 2016. Follow-up test programme in Nicaragua took place February 2017. The project is carried out in cooperation with Oro Industries, California and Recursos Encinal Nicaragua.

The majority of small-scale gold miners in Nicaragua use whole ore amalgamation meaning that they add mercury to the milling of their gold ore. The miners believe, correctly, that gold is captured by mercury during milling. What many miners do not realize is that milling mercury will form mercury flour which consist of tiny spheres of mercury (see photos below) which have lost the capacity of coalescing. The tiny droplets cannot be captured by the miners and are lost to their tailings. Another unfortunate capability obtained is that mercury flour easily floats on water and thus tends to escape processing. Mercury flour floating on water will end in rice paddies in the ocean and finally in the food chain.

This is a significant loss of mercury for the miners, but even worse is that mercury flour contains high amounts of gold which thus also escapes processing.

Peter Plates

Peter Plates

Mercury flour floating on water

Mercury flour floating on water