Cyanide

What is Sodium cyanide?

Sodium cyanide is a highly toxic chemical substance, also known as the sodium salt of hydrocyanic acid. One teaspoon of a 2% solution can kill a person. In general, fish and other aquatic life are killed by cyanide concentrations in the microgram per litre (part per billion) range; whereas bird and mammal deaths result from cyanide concentrations in the milligram per litre (part per million) range.

What is sodium cyanide used for?

First used on a large scale in the 1970s, cyanide mining allows miners to coax microscopic gold flecks from low-grade ore. Sodium cyanide now is the chemical of choice in the gold mining industry throughout the world and mining is the main sodium cyanide consumer worldwide, with 180 000 tonnes annually. More than 90% of the 2500 tons of annual global gold production is extracted using this chemical. The cyanide waste that is left over after gold processing is stored in large ponds. It is not unusual to have spills of the cyanide solution and the heavy metal-laced waters stored in the pond.

Throughout the world the cyanide process is left largely under-regulated which is why it tends to cause accidents like spills which in return poison the environment and affect human health. When sodium cyanide and the heavy metal-laced waters escape into the environment, they may contaminate ground water and surface water sources and kill fish and waterfowl. Cyanide also breaks down into compounds that are toxic to fish and it can bio-accumulate in plants and fish tissue.