Abstract
Preliminary economic mining feasibility studies of gold and copper deposits were conducted by the Bureau of Mines to estimate the mining costs in the Chugach National Forest, Alaska, in 1982. Lode and placer gold mines and open pit and underground copper mines were modeled. Cost data for the lode and placer gold mines were based on actual operating costs when available. Cost estimates for the copper mines were obtained using the Bureau's cost estimating system and may fall within +/- 25 pct of the actual costs. Underground gold mining appears economically feasible for a deposit with reserves of 100,000 tons containing greater than 0.5 Oz per ton over a 4-ft mining width. A gold price of $456 per ounce is required for the operation to break even. Placer gold mining operations of 100, 500, and 1,000 yd3 per day were modeled. At a gold price of $400 per ounce, these operations would break even at grades of 0.03, 0.012, and 0.009 Per ounce of gold, respectively. An 11,000-ton-per- day open pit copper mine appears to be economically borderline at metal prices of $0.70 Per pound of copper, $0.37 Per pound of zinc, $400 per ounce of gold, and $10 per ounce of silver. A 1,650-ton- per-day underground copper mine would require a copper price of $0.75 Per pound and a zinc price of $1.96 Per pound to be economic.
