Cyanide producers expanding to meet growing market

New North American plant capacity for the production of cyanide, the sodium and calcium variety, is in the works. Both E.I. du Pont (sodium) in the United States and Cyanamid Canada Inc. (calcium) have announced expansion plans in response to the boom in gold mining.

As reported (N.M., Dec 5/88), sodium cyanide is in such short supply world-wide that a “black market” in the chemical now exists. Most affected seem to be the smaller, first-time gold producers who are unable to secure long-term contracts for the poisonous, but important, leaching agent. Cyanide is one of the few chemicals which can dissolve gold and free it from waste rock.

Largest market area in North America for cyanide used in gold dissolutions is said to be the state of Nevada, where heap leaching operations are popular. In part because of the way each packages his product and the distances from the market areas, du Pont and Cyanamid (the U.S. parent is American Cyanamid) have come to dominate certain regions.

Sodium cyanide, white in color and available in Canada in briquette or granular form, is produced by du Pont at Memphis, Tenn. Robert Champ, an account manager for Canadian subsidiary Du Pont Canada Inc., said the plant there was recently expanded by 16,000 tonnes to 90,000 tonnes. Two new facilities expected to be in production next year are being built at Texas City, Tex., (45,000 tonnes) and at Mexico City, Mexico (9,000 tonnes). Capacity at the Texas City plant was increased from 27,000 tonnes in mid-construction. Sold in bulk

Competitor calcium cyanide is black in color; it is different from the sodium type in that it is sold in bulk and shipped as a dry product. The calcium variety contains about 48% the equivalent strength of sodium cyanide; for marketing purposes, it is priced competitively on a 100% real basis, delivered to the customer.

Cyanamid has been producing its AERO brand (calcium) cyanide at its Niagara Falls, Ont., plant for more than 70 years, George Roberts, chemicals division manager, said. The planned expansion, to come on stream during the first quarter of 1989, will double the company’s manufacturing capacity to produce cyanide, he said.

Because of the shipping costs associated with the Cyanamid product, it stands to reason the company’s main customers would be in central Canada. Roberts estimated his company’s share of the cyanide market for gold dissolutions in Ontario and Quebec is 80-85%; for the country as a whole, he estimated his company’s share to be about 50%.

Safety is emphasized in the handling of the Cyanamid product, Willard Thomas, marketing manager for mining products, said. “We prefer to supply in bulk from a safety point of view,” he said. He also explained that company representatives make mine site visits to check equipment.

A closed-system process is used to deliver the cyanide product by truck to the mine mill, Roberts said. “The cyanide never sees a human being until it is in solution form,” he said.

Each pound of calcium cyanide shipped might contain 12-15% lime, Roberts said, which is used in the milling process as a pH modifier. Raw material

The key raw material in sodium cyanide is hydrogen cyanide, which Champ said is either synthesized or obtained in byproduct form.

To feed its expanded, yet-to-be- completed Texas City plant, du Pont says it will obtain additional hydrogen cyanide through an expansion of Sterling Chemicals’ acrylonitrile facility in the same city. Hydrogen cyanide is a byproduct of acrylonitrile production. Sterling will operate the sodium cyanide facility, to be built on its property, while du Pont will own the plant and market the sodium cyanide.

Champ estimated his company’s share of the North American cyanide market for gold dissolutions to be about 50%.

Other major producers of sodium cyanide planning to build facilities in the United States in the coming years include the German firm Degussa.