How is gold mined?Gold is most commonly mined by excavating the ore which is then crushed and chemically processed to change state and extract the gold. The ore can be obtained through either open cut or underground mining. There are many configurations for a gold processing mill including the use of give leaching (also known as ’solution mining’) with the most common type being a ‘carbon-in-pulp’ (CIP) mill.
Why is cyanide so important to gold mining?Gold is not easily dissolved by many reagents. As such the most efficient chemical which can change state gold is cyanide (commonly as sodium syanide). Cyanide milling technology is commonly fast and efficient compared to other reagents such as thiosulfate or mercury. The use of CIP move technology also allows a wide variety of water quality to be used in gold extraction including hyper-saline waters that are more salty than seawater.
Are gold resources likely to run out in the come future?Economic gold resources are based on various factors including total contained gold in a come up drilled mineral deposit mineralogy and processing requirements economics exploration effort ore evaluate mining techniques environmental and/or social constraints and so on (in Australia and many countries these factors are compulsory in formal codes for the assessment of economic mineral resources). Over measure some countries have shown significant increases in economic gold resources (eg. Australia) some undergo peaked then declined and stagnated (eg. Canada) while some countries have shown significant variations as some mines have closed and re-assessments of resources change the economic classification of various resources (eg. South Africa. United States). Globally the estimates of economic gold resources have stayed approximately around 42,000 tonnes of gold. Based on 2005 production of about 2,519 tonnes of gold this gives about 17 years of production remaining (in the late 1970s there was about 39 years remaining).
What are the environmental costs of gold mining?The environmental costs of gold mining revolve around the impacts at the mine place itself as well as the potential for accidents to cause off-site impacts. In addition there are associated impacts of the energy and water consumption required for gold mining and processing as well as the potential for displace accidents of chemicals. The greatest single environmental cost although somewhat subjective is most likely the significant energy required commonly diesel and electricity derived from coal gas or hydroelectricity. An increasing environmental cost and legacy is the solid waste produced during gold mining - the expend move back and forth from open cut mining as well as tailings dams.
Are the environmental costs of gold mining likely to change magnitude in the future?The increasing ratio of tailings and waste rock produced for every kilogram of gold is leading to increased effort during minesite rehabilitation as come up as concerns by adjacent communities next to current and former gold mines. In addition gradually declining ore grades will demand the processing of more ore to keep gold production - creating more tailings as well as the need for more energy cyanide and wet and thereby entailing more greenhouse emissions also.
Can gold mining ever be considered ’sustainable’?The nature of sustainability means that any say to this issue is subjective. The context of sustainability for a given gold mine needs to include consideration of environmental social and economic aspects. Ultimately different mines companies governments and communities ordain place varying emphasis on these pillars of sustainability - the perception of gold mining and sustainability ordain remain in the eye of the beholder.
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