Canada’s third tailings re-treatment project is scheduled to start up in Yellowknife this May. Between June 15 and Aug 28 last year, owner Giant Yellowknife Mines ran a pilot plant operation to find the optimum levels of reagents for a commercial operation. That commercial- scale plant, which cost about $15 million, should be running this summer to produce a total of 37,400 oz for the year.
Giant has deposited gold mine tailings in three ponds north of its gold mine in Yellowknife for the past 39 years. Two of these, the central and north ponds, are the target of the tailings re-treatment project. About 27 drill holes spaced 2 ft apart indicate there are seven million tons of tailings, enough for five years of plant operation.
The average grade of the tailings is 0.067 oz gold per ton with individual pockets grading as high as 0.114 oz. This low grade ruled out the use of a dredge to mine the tailings, so a water gun concept, used successfully in South Africa, will be employed.
Metallurgical tests by Lakefield Research indicate the Giant project will be able to attain recoveries of 40% after 48 hours of leaching. A carbon- in-leach recovery system will be used.
Re-claimed tailings will be deposited in a new northwest pond. The total profits generated after payback by the project, which is expected to cost $25.5 million, is estimated to be $63.6 million. Giant Tailings Notebook Location: ……. Yellowknife, N.W.T. Major owner: ……. Giant Yellowknife Mines Commodity: ……. gold Production decision: ……. 1987 Start-up: ……. May, 1988 Capital costs: ……. $25.5 million Reserves: ……. 7 million tons grading 0.067 oz gold per ton Mining method: ……. water monitors; slurry pumped to mill Milling: ……. cyanidation (no re-grind) Production rate: ……. 1.4 million tons per year for 37,400 oz in 1988 Production costs: ……. $5.24 per ton or $256(US) per oz Major contractor: ……. Lakefield Research (metallurgy) Status ……. preproduction
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