About Sodium Cyanide

To most people, the word "Cyanide" triggers an immediate negative reaction. Sodium cyanide is a dry, solid, non volatile product. Although highly toxic, it is a low hazard chemical, easy to transport and use safely. Whether in a dry or solution form, with proper transport, handling and disposal measures, cyanide can be a safe effective asset to a variety of industries and consumers.

Cyanide information

  • Cyanide is naturally occurring molecule made up of carbon and nitrogen
  • The gold mining industry has been using cyanide for gold extraction for many decades
  • Cyanide is a widely used chemical that is essential to the modern world. More than 1,300,000 tonnes are produced annually
  • Cyanide is used in many industries, mining uses 18% of total world cyanide production
  • Like many substances (alcohol), it is deadly when ingested in a sufficiently high dose, but it does not cause chronic health or environmental problems when present in low concentrations
  • Cyanide decomposes readily by natural physical, chemical and biological processes and does not persist in the environment
  • Cyanide is not carcinogenic or radioactive
  • Is not a heavy metal or cumulative and should not be confused with acid drainage
  • Cyanide can be manufactured, stored, transported and used in a safe manner
  • A recent EU directive calls for levels of less than 10 ppm cyanide in the next 10 years. Thracean Gold Mining will use INCO’s SO2/Air process which reduces cyanide concentrations released into the tailings pond to less than 1 ppm – actual achieved values will be 0.1-0.2 ppm*

    Environmental Protection Agency regulations in the US state that the highest level of cyanide allowed in drinking water is 0.2 ppm

*An estimated cyanide concentration of 126 ppm was present in the large spill caused by a poorly built tailings dam in the accident at the Baia Mare goldmine at Sasar, Romania in January 2000.

Natural Occurrences of Cyanide

  • Cyanide is formed naturally. It is produced and used by plants and animals.
  • Hydrogen cyanide (HCN) exists in many fruits, vegetables, seeds and nuts, including apricots, bean sprouts, cashews, cherries, chestnuts, corn, kidney beans, lentils, nectarines, peaches, peanuts, pecans, pistachios, potatoes, soybeans and walnuts.
  • Over 2,000 natural sources of cyanide, including various species of arthropods, insects, bacteria, algae, fungi and plants.
  • Plants such as alfalfa, sorghum and cassava are known sources of cyanide poisoning to livestock and humans.
  • Cyanide compounds are also present in such everyday sources as automobile exhaust, cigarette smoke, and road and table salt.


Industrial Uses of Cyanide

  • Cyanide is mainly used in the chemical industry.
  • 80% of total cyanide production is used to produce nitrile, nylon and acrylic plastics.
  • Other industrial applications include electroplating, metal processing, steel hardening, photographic applications and synthetic rubber production.
  • Cyanide is used in pharmaceuticals such as the anticancer substance laetrile and the blood pressure–reducing drug nitroprusside.
  • Cyanide compounds are used in surgical dressings that promote healing and reduce scarring.
  • 20% of cyanide produced is sodium cyanide, a solid form that is easy and safe to handle.
  • Of this, 90% (i.e. 18% of total production) is used in mining, mostly for gold recovery.

Cyanide Use in Gold Production

  • Gold mines use very dilute solutions of sodium cyanide (NaCN), from 0.01% to 0.05% cyanide (100 to 500 parts per million)
  • The process of metal dissolution by sodium cyanide is called leaching
  • Gold mines have used cyanide as the leaching agent for gold for over 100 years
  • At Perama Hill, after leaching in tanks, the barren solution will be collected along with the solid wastes (tailings) in a contained tailings impoundment system (TMF)
  • The processing plant will be a zero discharge system

        Cyanide destruction will be a chemical oxidation process called the SO2/Air process (by INCO) Mine management practices with respect to cyanide will be made public, as local communities need to be informed and aware of all mine activities









Mark J. Logsdon, MSc

Karen Hagelstein, PhD, CIH

Terry I. Mudder, PhD


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