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(More customer reviews)Silver has the highest sheen and conductivity of any metal. "Silver Mines" reviews both underground and open-pit silver mining, as well as providing historical information.
The "Lucky Friday" underground mine in Northern Idaho descends 6,200 feet and has been operating since the 1940s. It contains 20 miles of tunnels, some stretching out for a mile and 12' wide and 16' high. It is dark, wet, warm (120 degrees w/o cooling, 82 degrees with), and loud (sound of echoing machinery). The hoist lifts miners in/out at 1,500'/minute; maintenance sections exist at each level. Most areas are lit only by miners' cap lights and machinery headlights Its ore yields 15 oz. of silver for every ton, as well as lead and zinc.
Blast holes are drilled 8' deep in the falls, while 4' bolts are used to hold up the sides afterwards. Sixteen-ton trucks transfer the ore to the hoist and its ten-ton loads to the top. Lacking an overall communication system, a stench-producing chemical is poured into the ventilation system to warn miners of emergencies.
Processing underground ore begins at the crushing plant - crushers and a ball mill create a slurry which in which the desired metals are then frothed to the surface, scraped off, and dried, before shipment to a refinery in Canada.
Viewers then see photos of the Comstock silver mine in Western Nevada, and realize the enormous manual labor required then. Miners could only work a few minutes each hour because of the heat. Fire, dust from the air drills causing miner's consumption, and burns from scalding water generated by small volcanic vents presented major hazards. Enormous amounts of wood were used in stabilizing the underground walls.
Open pit silver mining is displayed at the Rochester mine near Lovelock, NV. Lower grade ore is processed via leaching; the higher grade ore is also leached after going through a crusher. This mine was closed in 2006, and the entire area (except the pit) is being reclaimed with natural vegetation.
The final segment of "Silver Mines" covers testing robotic underground loaders in Australia.
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