Southern Idaho and surrounding areas are going through a gold boom.
Newly discovered gold-bearing areas in Nevada may be as rich as the gold fields of South Africa, said Leendert Krol, director of investment relations with Newmont Gold Co. in Elko.The Nevada discovery, higher gold prices and a chemical leaching process have brought a new gold rush to the mountains of the West, including the South Hills in Twin Falls County. Another mining company also has announced a big gold strike near Salmon.
Discovery of new ore beds has led to more exploration, which in turn has led to more discoveries, Krol said. The relatively cheap recovery process and the promise of rich ore have attracted other mining companies to the area, and entrepreneurs have started companies to mine the newfound mother lode.
The new miners are extracting gold from ore that old-time prospectors couldn't even see. But the new methods are less damaging to the environment than the old placer mining process that washed away whole hillsides in search of the elusive metal, said George Boucher, Elko County manager.
Information about the Nevada discovery is scanty. Newmont Gold would talk only guardedly about the discovery that has turned Elko into a boomtown. The company owns mineral rights on more than 200,000 acres in north-central Nevada.
The process that, coupled with high gold prices, has brought mining back to Nevada and Idaho uses a cyanide solution to leach gold from crushed ore.
Idaho Gold started a test operation in October of a mine using this process in the Lava Creek field west of Arco.
The mine so far has produced 200 to 400 ounces of gold and about 1,600 to 1,800 ounces of silver. Gold currently sells for about $415 per ounce. The recovery cost could be as much as $300 per ounce of gold, said Collin Fay, project engineer for Idaho Gold.
The test phase includes mining and processing about 30,000 tons of limestone ore, which should be done by January, Fay said.
It appears to be quite successful, he said.
Field results have borne out lab studies, he said. The company expected to recover 70 to 75 percent of the gold in the ore and about 50 percent of the silver. To get the remaining metal out would cost more than the metal is worth, he said.
The company plans to build a full-scale processing plant next year to process up to 700,000 tons of ore annually.
When Idaho Gold Co. stops mining, the cyanide solution and leaching area will be neutralized using a solution similar to swimming pool chlorine or hydrogen peroxide, Fay said. The area will be recontoured and topsoil that was saved will be put in place and reseeded.
The leaching process uses a weak solution of cyanide, which is sprayed on crushed ore spread out on leach pads, said Dan Myers, project engineer with Noranda Mining Co. of Toronto.
The gold-bearing cyanide solution then runs into a pregnant pond, or holding pond. The gold is removed from the solution and electroplated onto steel wool. The steel wool then is burned and the residue sent to a refinery for final processing.
Myers said a ton of ore produces about 0.065 of an ounce of gold by this method.
The mining company, however, has more at stake than protecting the environment in making sure none of the cyanide solution escapes.
If the solution gets out, the gold goes out with it, Myers said. The leaching and pregnant ponds are double lined with leak detectors between the layers. All ditches also would be lined. The whole operation is designed for zero discharge, not just to protect the environment, but to protect our investment, he said.