Copper Ore Mining US
Copper Ore Mining
Copper is commonly extracted from surface, underground and increasingly, from in situ operations. In 2000, the principal mining States, in descending order, Arizona, Utah, New Mexico, and Montana, accounted for 99 percent of domestic production. Copper was also recovered at mines in three other States. Although copper was recovered at about 30 mines operating in the United States, 15 mines accounted for about 99 percent of production. At yearend, four primary smelters, four electrolytic and four fire refineries, and 15 solvent extraction-electrowinning facilities were operating.
Surface mining requires extensive blasting as well as rock, soil, vegetation, and overburden removal to reach lode deposits. Benches are cut into the walls of the mine to provide access to progressively deeper ore as upper-level ore is depleted. Ore is removed from the mine and transported to beneficiation plants for milling and concentrating. The concentrate is then smelted and refined. Open-pit mining is the primary domestic source of copper.
Underground mining entails sinking a shaft to reach the main body of ore. Drifts or passages are then cut from the shaft at various depths to access the ore, which is brought to the surface for beneficiation. While underground mines do not create the volume of overburden associated with surface mining, some waste rock must still be brought to the surface for disposal. Waste rock may either be returned to the mine as fill or put in a disposal area.
Solution (In Situ) Mining
Solution or in-situ mining requires drilling into the rock and using chemical solutions to dissolve lode deposits. During solution mining, the leaching solution (usually a dilute acid) penetrates the ore, dissolving soluble metals. This pregnant leach solution is then retrieved for recovery at a solvent extraction and electrowinning (SX/EW) plant.
Copper Beneficiation and Processing
The two major processes employed in the United States to recover copper from ores are classified as either (1) pyrometallurgical methods (copper processing), or (2) hydrometallurgical methods (copper beneficiation). Pyrometallurgical methods consist of smelting technology, and are widely used. Hydrometallurgical methods involve leaching and recovery by precipitation or electrowinning. These methods are gaining in extraction/electrowinning (SX/EW).
Last update: February 20, 2012