The primary methods used to extract minerals from the ground are:
- Underground mining
- Surface (open pit) mining
- Placer mining
The locationand shape of the deposit, strength of the rock, ore grade, miningcosts, and current market price of the commodity are some of thedetermining factors for selecting which mining method to use.
Higher-grade metallic ores found in veins deep under the Earth’s surface can be profitably mined using underground methods, which tend to be more expensive. Large tabular-shaped ore bodiesor ore bodies lying more than 1,000 feet (300 m) belowthe surface are generally mined underground as well. The rock is drilled and blasted, then moved to the surface by truck, beltconveyor, or elevator. Once at the surface, the material is sentto a mill to separate the ore from the waste rock.
Lower grade metal ores found closer to the surface can be profitably mined using surface mining methods, whichgenerally cost less than underground methods. Many industrialminerals are also mined this way, as theseores are usually low in value and were deposited at or near theEarth’s surface. In a surface mine, hard rock must bedrilled and blasted, although some minerals are soft enough to mine without blasting.
Placer mining is used to recover valuable minerals fromsediments in present-day river channels, beach sands, or ancientstream deposits. More than half of the world’s titanium comesfrom placer mining of beach dunes and sands.In placer operations, the mined material is washed and sluicedtoconcentrate the heavierminerals.
Learn more: The Lifecycle of a Mineral Deposit
