Gold - Pollution

Pollution

Gold production is associated with contribution to hazardous pollution. The ore generally containing less than one ppm gold metal, is ground and mixed with sodium cyanide or mercury to react with gold in the ore for gold separation. Cyanide is highly poisonous chemical, which can kill living creatures when exposed in minute quantities. Many cyanide spills from gold mines have taken place worldwide both in developed and poor countries which killed the marine life in long stretch of affected rivers. Environmentalists consider these pollution disasters as major environmental disasters. When mercury is used in gold production, minute quantity of mercury compounds enter in to water bodies causing heavy metal contamination of water. Mercury enters in to human food chain in the form of methyl mercury through fish, etc. Mercury poisoning in humans causes incurable severe retardation of brain functions.

Thirty tonnes of used ore is dumped as waste for producing one finger ring of gold. Gold ore dumps are the source of many heavy elements such as cadmium, lead, zinc, copper, arsenic, selenium and mercury. Water is unsuitable for human consumption if these heavy metals are found in more than one ppm concentration. When sulfide bearing minerals in these ore dumps are exposed to air and water, the sulfide transforms in to sulfuric acid which in turn dissolves the heavy metals facilitating their passage in to surface water and ground water. This process is called acid mine drainage. The gold ore dumps are considered as long term man made hazardous waste next only to nuclear waste dumps. Billions of dollars need to be spent to mitigate the heavy metals pollution from worldwide gold ore dumps which are increasing every year.

Gold extraction is also highly energy intensive industry (25 kW·h of electricity per one gram of gold production) to extract ore from deep mines and to grind the large quantity of ore for further chemical extraction.