The highly toxic concentrates are carried in stainless steel pots (four per truck), which are securely covered with a fibreglass lid in the event of an accident. But with a minimum 480,000 km of driving experience each, these drivers are not likely to have one. Each truck takes a 2-leg journey every 22 hours. The first leg is a 12-hr return trip from Whitehorse to Faro and back, a distance of 760 km. And the second leg runs from Whitehorse to Skagway and back over the Haines Road, often bringing milling reagents back with them. This leg of the trip takes eight hours. During the winter months, most of the trip is done in the dark. It takes 60 maintenance personnel at Whitehorse to keep the 40-truck fleet in top running condition. Each vehicle costs about $230,000.
From Skagway, some of the concentrates are shipped to Japanese smelters; the rest go to Korea and Europe. Shipments started in June, 1986, after Curragh Resources took over the mine from Cyprus Anvil Mining Corp. Originally, Faro had about 58 million tonnes of proven reserves; when Curragh took over, the pit was about 60% mined out. That meant there was enough for six more years of operation. Now, it looks like the Faro deposit will be completely mined out in late 1991. Curragh plans to mine a small, 2.5-million-tonne portion of the deposit by underground methods. Access will be provided by an adit in the south face of the pit. Production from this underground portion could extend into 1993.
To continue mining lead/zinc at Faro beyond 1991 at current rates, Curragh has been building roads of its own. Since about late 1986, the company has been using the waste from the Faro pit as a roadbed for an access road from the mill to the Vangorda Plateau, 14 km away. At the end of 1988, the road was about 8 km long. Three deposits, two mineable by open pit and one located at greater depth, have been outlined on the plateau. They contain sufficient reserves for about 10 more years of mining at present rates. Pre-stripping, dewatering and overburden removal is under way and the company expects to be producing ore from one of the pits by late 1991 or early 1992. Two new pits will likely be developed to replace production from the Faro pit. The Grum deposit contains 30.6 million tonnes of mineralization, grading 8.4% combined lead/zinc (5.2% zinc and 3.2% lead) and 57 g silver per tonne. And the much smaller Vangorda deposit contains 7.5 million tonnes at 4.9% zinc, 3.8% lead and 54 g silver per tonne.
The third known deposit, the Dy deposit, has reserves of 21.1 million tonnes at a depth of about 550 m. This deposit, which has average grades of 6.7% zinc, 5.5% lead and 84 g silver per tonne, could be mined by underground methods.
This summer, about 100,000 tonnes of mineralization will be mined from the Vangorda deposit for metallurgical testing. Curragh holds about 4,200 ha of ground in the area, comprising 2,208 claims. Most of it is in good standing well into the 1990s. No other company is actively exploring in the area.
Milling capacity at Faro is about 13,500 tonnes per day. And Curragh is aiming to process 4.8 million tonnes of ore in 1989. About 22.2 million tonnes of waste were mined in 1988, coming from both the Faro pit and the stripping program on the Vangorda Plateau. The stripping ratio in the Faro pit was less than 3:1 in 1988. Grades were 4.6% zinc, 3.0% lead and 41.8 g silver per tonne.
The company’s target is to produce 580,000 tonnes of concentrates in 1989 (390,000 tonnes of concentrates, grading about 50% zinc and 210,000 tonnes of concentrates, grading about 60% lead). Recoveries in 1988 were about 77%-78% for zinc and 78%-79% for lead. Total costs are not available, but a mining and milling cost of $41.25 per ton of concentrate produced, which was reported earlier, is low, according to Kurt Forgaard, Curragh’s president and chief operating officer.
Mineral processing begins with three stages of crushing: minus 8-inch, minus 2-inch and minus 5/8-inch, followed by rod and ball mill grinding which reduces the ore to 80% minus 200 mesh. The work index of the ore is somewhat variable but averages about 13 kW-hrs per tonne. Flotation consists of one stage of lead roughers and three stages of lead cleaning. About 52% of the silver reports to the lead concentrate.
When we last visited Faro, in October, 1987, Curragh was working on column flotation cells, 4 ft in diameter and 48 ft high. That work is ongoing.
De-watering is achieved using coal- fired disc filters. Coal comes from Ross River, Y.T. Should the price of coal rise significantly, it may become economic for the company to purchase pressure filters.
Daily production rates are about 500 tonnes of lead concentrates and 1,100 tonnes of zinc concentrates. Moisture content is about 6.0% for lead and 7.0% for zinc.
Curragh has purchased two new Dart loaders, equipped with 12-cu-yd buckets. The mine has 32 trucks: sixteen 120-ton Wabco trucks and sixteen 170-ton trucks (12 Euclids and 4 Unit Rigs). The 120-ton units haul ore (capacity of crusher) while the 170-ton units haul waste. About 40% of the waste goes to the Vangorda road. Each day, about 100,000 tonnes of ore and waste are hauled over a distance of about 2 km. Average tire life is 6,000 hrs.
There are four shovels: three P+H 2100s and a Marion shovel, both with 15-cu-yd dippers. Two shovels are operating.
The company looked at computer dispatching, but will not be using it. Total number of employees at the mine is about 450. A new, 3-year labor contract expires in 1991. Patrick Whiteway
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