History
Gold was discovered at Summitville in 1870. By 1885 there were more than 250 individual claims in operation. The site was soon mined out, with the weather of the 3,500 m high site adding to difficulties. The site was re-opened on a number of occasions for gold or other metals but with little success, and prior to the site's acquisition in 1984 the last survey was in the early 1970s for copper. The total amount of gold extracted from the site from 1873 until 1959 was around 257,600 troy ounces (8,012 kg).
In 1984 an area of 1,230 acres (5.0 km2) was acquired by the Galactic Resources Ltd. subsidiary Summitville Consolidated Mining Company, Inc. (SCMCI). They began a new large-scale open pit operation covering 550 acres (2.2 km2). New techniques were used to extract gold from otherwise uneconomic ore.
The mining involved the treatment of pyritic ore with a sodium cyanide solution to leach the gold out of the ore—heap leaching (see also cyanide process). The solution (leachate) was then removed from the ore and the valuable metals extracted using activated carbon. SCMCI leached around 10 million tons of ore on a 73-acre (0.3 km2) heap leach pad. The mining operations were finished in October 1991 with the leaching continuing until March 1992. A total of 294,365 troy ounces (9,155.8 kg) of gold and 319,814 troy ounces (9,947.3 kg) of silver were recovered. SCMCI then closed the site and converted on-site equipment for the detoxification process, with around 160 million U.S. gallons (610,000 m³) of stored water needing treatment.
Read more about this topic: Summitville Mine
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