Consequences of a soaring gold price for gold producing countries and the global environment.
2009 (English)In: Securing the Future and 8thICARD, Skellefteå, 2009Conference paper (Other academic)
The presently soaring gold price adds to hazards threatening the sustainability of fishing and agriculture as means of support to living. This is by increased gold mining and related emissions of mercury and cyanide into the environment. Amalgamation, practiced in more than 50 countries, results in that metallic Hg is emitted to air, soil, and water and subsequently transformed to very toxic methyl-Hg and bio-accumulated in fish. Thereby, this highly nutritive feeding source eventually is ingested and becomes a poison to man.
Four methods for gold recovery: amalgamation, cyanide leaching, a shaking sluice, and Cleangold® sluices, were compared in a case study performed at the largest gold mining village in the Philippines. The results show that the amalgamation method is presently used on all ores, in spite of gold recovery rates of 10–35% of initial gold content of the ore. With a light microscopy and photomicrographs, we documented that the following factors contribute to the low recovery: small and occluded gold grains and gold grains with oxidized surfaces that do not amalgamate. As a consequence, the miners are sending all amalgamated ore tailings for cyanide leaching. This was the most efficient of the methods studied, recovering up to 95% of initial gold content. The Cleangold® sluices recovered more gold than amalgamation, although gravimetric methods have limitations on the actual specific ore. Therefore, a combination of manual panning and/or Cleangold® sluices followed by cyanidation is the best solution under present conditions, followed by cyanidation alone. The used cyanide solution must be properly handled to not threaten the food security.
Transition to less hazardous gold mining is urgent, considering that gold is a limited stored resource. Agricultural fields and fish populations are at the contrary fund resources, which will yield a return for an indefinite future if properly managed. Loans for investment in safe and efficient gold extraction technology, information and practical training of the miners, political and scientific guidance of the informal mining sector, restrictions on Hg availability and on sales from industrialized countries are suggested to counteract the present worst case situation, where amalgamation is followed by cyanidation. This combination increases the bioavailability of Hg lost. into the environment.
Place, publisher, year, edition, pages
Amalgamation; Cyanide; Gravity Separation; Mercury; Small-scale Gold Mining; Socio-Economic Structure
IdentifiersURN: urn:nbn:se:uu:diva-115471OAI: oai:DiVA.org:uu-115471DiVA: diva2:295530
Paper was presented at the 2009, Securing the Future and 8thICARD, June 22-26, 2009, Skellefteå, Sweden.
ProjectsKvicksilver i miljön/Mercury in the environment