With two years of life remaining at its Picacho mine in California, Glamis Gold (TSE) hopes to increase gold production to nearly five times the current rate by 1990. Property acquisitions and joint venture agreements signed over the past two years constitute a reserve of one million ounces which will be exploited over the next few years, says James Billingsley, a company director.
In fiscal 1990, he forecasts gold output will be about 116,000 oz, almost double the expected 1989 rate and five times the 24,400 oz anticipated this year.
Waste stripping of ore in the wall of the Apache pit at Picacho is well under way and will continue for the balance of the year. Starting in 1989, 600,000 tons of ore grading 0.04 oz gold per ton will be piled on leach pads from the Apache area. About 5.5 million tons of ore are now under leach and this should last until the Apache ore is available.
No crushing or agglomeration is required at Picacho, partly because the ore is friable and it breaks down on the pad exposing new surfaces to cyanide solution which dissolves the gold particles. Because of the clay content, the leaching rate is relatively slow and a leaching lifetime of two years is foreseen after mining ceases.
Recent exploration at Picacho has located an updip portion of the Dulcina deep ore that may be economic to mine; the feasibility of producing from this source is under study, says Billingsley. Ore is currently being mined on a year- round basis by open pit mining methods from the Dulcina pit. Mine life projections do not include the deep Dulcina ore, he confirms.
At the company’s Yellow Aster property 125 miles northeast of Los Angeles, crushing of ore from the Lamont zone for test leach purposes has been completed. Leaching is under way and in May 69,000 tons of ore, containing 1,900 oz gold, was delivered to leach pads. He believes that Yellow Aster has “pretty well turned the corner” and he says it “takes about 400 to 500 oz gold per month to pay our costs.”
A screening plant is producing 2,000 tons per day of material from the Descarga dumps, all of which has been grading 0.03 oz. An emitter system has been installed on the Descarga and Lamont leach piles which allows cyanide to drip from closely-spaced small diameter pipes. This approach is cheaper and there are practically no evaporation losses. Coverage is also greater, he notes.
Production permits are anticipated for the Yellow Aster main pit by January, 1989. Mining should get under way by next March with production of 2,000 oz gold per month expected by June, 1989. Projected yearly production from all three sources (Lamont, Descarga, Yellow Aster main pit) is 5,400 oz in 1988, 31,000 oz in 1989, and 34,000 oz for fiscal 1990.
A final heap leach test is being conducted at the company’s Cuervo Gold (Sullivan mine) project in Nevada. All metallurgical problems appear to have been resolved, he states, adding that recoveries have reached 75% for gold in 80 days from crushed ( in) material. Pit design and mine planning are nearly completed and this project could generate 12,000 oz of gold in 1988 and 15,000 in 1990.
Permits for leaching a minimum of 250,000 tons of ore per year are expected for the Alto mine in Calaveras Cty., Calif., by year-end. Projected production for fiscal 1989 is 4,400 oz gold and 28,600 oz the following year. Drilling is under way at the San Cristobal mine in Chile where proven and probable reserves are nine million tons grading 0.049 oz gold. Bids by mining contractors to mine, crush and place ore on leach pads have been called for. Initial production is scheduled for February, 1989, and 9,000 oz of gold output is projected for fiscal 1989 and 24,000 oz the following year.
Glamis is involved in a number of other joint venture properties which are not included in its production forecasts.
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