Evaluation of a new method using magnetic sluices for mercury-free small-scale gold mining in the Philippines.

• Approximately 100 000 people are involved in small-scale gold mining a in the Philippines. They mainly use the amalgamation and/or cyanidation processes. The use of mercury started in the 1980’s, when the price of gold went up. The workers live in thesame place as they work, they do not use safety equipment and the tailings are generally left anywhere. The concentrations of mercury in drinking water, soils, sediments, tailings and fish near gold mining operations exceed in general national and international limits.The aim of this study was to evaluate a new method for gold recovery, suitable for smallscale miners and in which mercury, cyanide or other chemicals are not used. Interviews with some miners were also performed in order to understand the complex situation from a miner’s perspective and evaluate the possibilities to improve the situation. The gold separation method, Cleangold (US patent granted in July 1999, #5,927,508) is developedby David Plath, USA, and uses magnetism to create riffles in a simple sluice, for a physical separation of gold from grains with lower density. The study was performed at five different sites in the Philippines (Diwalwal, Mainit, Acupan, Balatoc and Paracale).The gold recovery from the different sites varied both between and within the sites. The highest recovery was obtained in Balatoc (73%) and the lowest in Acupan with a top value of 15%. In comparison, the recovery using the amalgamation method is generally between 25 and 50% at the sites and at cyanidation estimated to approximately 90%. The chances of reducing the use of mercury are large, for example by adding mercury in the final step only, while panning, in case the magnetic sluices cannot completely replace amalgamation. In conclusion: the miners want and need a change. The obstacles for development are lack of technology and knowledge, unstable economy, habits and the fact that mercury and cyanide are easily accessible on the market. Further, for development and adaptation of environmentally benign methods, stricter control/legislation and accessible loans/micro credits to the miners are important. Industrial countries could play an important role by transferring appropriate knowledge rather than mercury.

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