EDITORIAL & OPINION — FACTS ‘N’ FIGURES — No substitute for cyanide

Cyanide is the main chemical used by the precious metal mining industry, and the industry could not exist without it. No other chemical available can separate gold or silver (in a process called leaching) from Mother Earth as efficiently and economically as cyanide.

In the United States, the mining industry consumes about 117 million lbs. of cyanide per year, compared with consumption by the plastics industry of 1 billion lbs. per year.

The chemical formula for cyanide is CN. It is a simple organic compound of carbon and nitrogen. Mining companies usually purchase cyanide as the compound sodium cyanide, or NaC. Cyanide occurs naturally or can be manufactured from ammonia, as a byproduct of acrylic filter and plastics, or as a byproduct of combustion. Cyanide occurs in low concentrations in radishes, cabbage, cauliflower, broccoli, turnips and Brussels sprouts. Apple and other fruit seeds are high in cyanide.

The industry, its suppliers and regulators work diligently to ensure that cyanide is always transported, handled and stored safely. The toxic effect of cyanide should not be downplayed. The form of cyanide used in mines is more stable and easier to handle than pure cyanide.

The latter form, which is not used in mining operations, is a fast-acting poison capable of killing a person in minutes by cutting off the flow of oxygen from the blood stream to body tissue. Exposure to diluted cyanide is handled readily by the body, and there are no carcinogenic, teratogenic or chronic effects from exposure. Even exposure to concentrated solutions of cyanide are not fatal with immediate first-aid treatment.

Liquid cyanide, or concentrated solution, is shipped in specially designed, double-hulled tanker trucks. When shipped in cold climates, cyanide must be heated to prevent crystallization inside the tank. These trucks are monitored around the clock through the global positioning system and satellite tracking. The advantage of liquid cyanide is the absence of cyanide dust.

Dry cyanide is pressed into small briquettes and shipped in specially designed containers. Although this form of cyanide is safer to transport (since a ruprture in any of the containers wouldn’t result in a spill), it creates hazardous dust. Those involved with loading and unloading the cyanide must wear respirators to protect against inhalation.

At the mine site, cyanide, both liquid and dry, is diluted. After this step, dry cyanide, which is pure, and liquid cyanide, which has a concentration of about 30%, become a weak solution with a concentration of about 2% cyanide.

All mine-site storage tanks, pipes, ponds or any other areas which many contain cyanide are required by law to have an active, self-draining, double containment system. This means that in the event of a leak, a back-up system is in place to contain it.

Cyanide can be broken down or destroyed by both nature and man. The addition to cyanide of chemicals such as chlorine, ferrous sulphate, hydrogen peroxide and sulphur dioxide completely destroys it.

Apart from the mining industry, cyanide is used in painlkilling and anti-inflammatory drugs, herbicides, lactic acid, and food processes such as the decaffination of coffee.

— The preceding appeared in Nevada Miner, the publication of the Nevada Mining Association.