Open-pit metal mines are often shaped like an inverted cone, with the ore and overburden being drilled and blasted, then loaded and transported by shovel-and-truck systems. Mine trucks that weigh between 106 and 260 tons, and carry payloads from 136 to as much as 400 tons, transport these materials from the pit bottom along unpaved, slowly rising, winding haul roads to dumping areas outside the pit, or to a primary crusher station several hundred meters from the pit rim. Having run through the primary crusher, in larger operations the ore is then often transported via overland conveyors to the concentrator at rates of 10,000 mt/h and more.
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