This was the situation in 1986 when Yukon-Charley Rivers National Preserve acquired a group of mining claims along Coal Creek, a tributary of the Yukon River roughly eighty miles from the U.S.-Canada boundary. And when the mining is done, these hazardous materials often remain.
This operation requires not only men and machines but also chemicals, heavy metals, and large amounts of petroleum-based fuels and lubricants. To make it pay, miners turn the earth upside down by excavating the richest mineral-bearing gravels and casting away all but the dust, flakes and nuggets of gold. Industrial placer gold mining is a messy business. National Park Service Natural Resource Report:Ī history of NPS clean-up efforts at the historic Coal Creek Mining District This early success convinced McRae and Patty to invest in a second, nearly identical dredge which they constructed just five miles to the west in the Woodchopper Creek drainage. In its first two weeks of operation the dredge brought in between sixty cents and one dollar per cubic yard of gravel and yielded $27,000 in gold. By applying heat, the mercury can be removed to be used again and the gold can be melted into bars. Using a technique that dates back hundreds of years, the dredge operators laced their sluice boxes with mercury which chemically bonds with gold and allows the tiniest particles of gold to be scooped up in a blob called an amalgam. To do this the dredge functioned like an enormous washing machine which pulled in thousands of cubic yards of gravel with its 62-unit bucketline, tumbled and sprayed the material to segregate large rocks from finer material, and used a system of sluice boxes to allow bits of gold to be captured while the waste rock was discarded out the back. The theory behind gold dredging is the same as any placer mining operation: separate sand and gravel from gold. The Coal Creek dredge stacker and tailing piles.
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