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Types of Diamond Mining
Diamonds and other precious and semi-precious gemstones are extracted from the earth namely three main types on mining. These diamond extraction methods vary depending on how the minerals are deposited within the earth, the stability of the material surrounding the desired mineral, and the peripheral damage done to the nearby environment. The standard methods of extraction for diamonds are:
1. Artisanal Mining
2. Hard Rock Mining
3. Marine Mining
4. Open Pit Mining
5. Placer Mining
Artisanal Mining: Artisanal diamond mining (aka "small-scale mining") involves nothing more that digging and sifting throughout mud or gravel river-bank alluvial deposits (above, right) with bare hands, shovels, or large conical sieves. Workers who work in artisanal diamond mining are called "diamond diggers". Artisanal diamond mining is a form of "subsistence based" non-mechanized mining that is used in inferior countries throughout the world.
Artisanal diamond mining is used throughout West Africa, in conflict zones where mechanized mining is impossible and unsafe. Artisanal diamond mining accounts for 90% of Sierra Leone's diamond exports and is the country's second biggest employer after subsistence farming. It is also used extensively in Angola, the Congo (DROC), and Liberia.
Hard-Rock Mining: The term "Hard Rock Diamond Mining" refers to a variety of techniques used to mine gems, minerals, and ore bodies by tunneling underground and creating underground "rooms" or "stopes" supported by timber pillars of standing rock. Accessing the underground ore is achieved namely a "decline" or a "shaft". A "decline" is a spiral tunnel which circles the side of the ore deposit or circles around the deposit. A "shaft" is vertical tunnel used for ore transport and runs adjacent to the ore. A "decline" is normally used for personnel and machinery access to the ore.
Marine Mining: Marine mining technology only became commercially possible in the early 1990s. Marine diamond mining employs both "vertical" and "horizontal" techniques to mine diamonds from offshore placer deposits. Vertical marine mining uses a 6 to 7 meter diameter drill head to cut into the seabed and suck up the diamond bearing objects from the sea bed. Horizontal mining employs the use of Seabed Crawlers (remotely controlled, CAT-tracked underwater mining vehicles) move diagonally the sea floor pumping gravel up to an offshore vessel.
Open Pit Mining: Open-Pit diamond mining or "Open-Cast Mining" (top of page, middle) is a method of mining rock or minerals from the earth by removal from an open pit or burrow. Open pit mines are used when deposits of minerals are originate near the surface or along kimberlite pipes. Open pit mining is used when the "overload," or surface material covering the deposit, is relatively thin and/or the minerals are imbedded in structurally unstable earth (cinder, sand, or gravel) that is unsuitable for tunneling. "Pit lakes" tend to form at the bottom of open-pit mines as a result of groundwater interruption.
Placer Mining: Placer Diamond mining, also called as "sand bank mining" (top of page, right) is used for mining diamonds and minerals from alluvial, eluvial, and or colluvial secondary deposits. Placer Mining is a type of open-pit or open-cast mining used to extract minerals from the surface of the earth without the use of tunneling. Mining is accomplished using water pressure (a.k.a. hydraulic mining), mechanized surface excavating equipment, or digging by hand (artisanal Mining).