is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein, or (coal) seam. Materials commonly recovered by mining include bauxite, coal, copper, diamonds, iron, gold, lead, manganese, magnesium, nickel, phosphate, platinum, rock salt, silver, tin, titanium, uranium, and zinc. Other highly useful materials that are mined include clay, sand, cinder, gravel, granite, and limestone. Any material that cannot be grown from agricultural processes must be mined. Mining in a wider sense can also include extraction of petroleum and natural ga
The oldest known mine in the archaeological record is the "Lion Cave" in Swaziland. At this site, which has a radiocarbon age of 43,000 years, paleolithic humans mined for the iron-containing mineral hematite, which they presumably ground to produce the red pigment ochre.
Sites of a similar age where Neandertals may have mined flint for weapons and tools have been found in HungaryAnother early mining operation was the turquoise mine operated by the ancient Egyptians at Wady Maghareh on the Sinai Peninsula. Turquoise was also mined in pre-Columbian America in the Cerillos Mining District in New Mexico, where a mass of rock 200 feet (60 m) in depth and 300 feet (90 m) in width was removed with stone tools; the mine dump covers 20 acres (81,000 m²).
Black gun powder in mining was first time used in a shift Bartolomej in mines under the town Banská ?tiavnica, Slovakia in 1627. There is 12000 kilometers of tunnels under this small town drived for a 1000 years.
Mining techniques can be divided into two basic excavation types:
Surface miningStrip Mining
is a type of mining used to extract deposits of mineral resources that are close to the surface. In most forms of surface mining, heavy equipment, such as earthmovers, first remove the overburden (the soil and rock above the deposit). Next, huge machines such as drag line excavators extract the mineral. Surface mining generally leaves large devastated areas called spoil banks unless the land is recovered and it has a huge negative effect on the local ecosystem and the environment. There are four main forms of surface mining.
Types of surface mining
Strip mining is the practice of mining a seam of mineral ore by first removing all of the soil and rock that lies on top of it (the overburden). It is similar to open-pit mining in many regards. Strip mining is also used to extract the oil-impregnated sand in the Athabasca Tar Sands.Open-pit mining
Strip mining is only practical when the ore body to be excavated is relatively near the surface. Since colossal quantities of material often need to be removed, the excavating machinery used in strip mining is often among the largest such equipment ever constructed; drag line excavators and bucket-wheel excavators are common examples.
There are two forms of strip mining - area strip mining, which is used on fairly flat terrain, to extract deposits over a large area. Contour strip mining, usually used in hilly terrain, involves cutting terraces in mountainsides following the contour of the land.
Open-pit mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow. The term is used to differentiate this form of mining from extractive methods that require tunneling into the earth. Open-pit mines are used when deposits of commercially useful minerals or rock are found near the surface; that is, where the overburden (surface material covering the valuable deposit) is relatively thin or the material of interest is structurally unsuitable for tunneling (as would be the case for sand, cinder, and gravel). Where minerals occur deep below the surface—where the overburden is thick or the mineral occurs as veins in hard rock— underground mining methods are used to extract the valued material. Open-pit mines are typically enlarged until the mineral reserve is exhausted.Mountaintop removal
Mountaintop removal (MTR) is a relatively new form of coal mining that involves the mass restructuring of earth in order to reach sediment as deep as 1,000 feet below the surface. Mountaintop removal requires that the targeted land be first clear-cut and then leveled by dynamite. The debris created is typically scraped into a valley fill - a practice that has twice been ruled illegal by a federal judge in accordance with the Clean Water Act.Dredging
Dredging is a method often used to bring up underwater mineral deposits. Although dredging is usually employed to clear or enlarge waterways for boats, it can also recover significant amounts of underwater minerals relatively efficiently and cheaply.