What is Open Pit Mining?

[janevictory]

Open Pit Mining

Open-pit diamond mining, also known as "open-cast mining" is a method of extracting rock and minerals from the earth by removal from a machine-dug open pit or burrow. Open pit mines are typically used when mineral deposits are found close to the surface or along defined kimberlite pipes.

Open pit mining is used when the surface material (overburden) covering the deposit is relatively thin and/or the desired minerals are imbedded within structurally unstable earth (cinder, gravel, or sand) that is unsuitable for tunneling. Small "pit lakes" tend to form at the bottom of open-pit mines as a result of groundwater intrusion.

[hbowers]

Open pit mining is generally useful for mineral deposits that are diffuse throughout a large area. Instead of mining out an area via tunneling and stoping (collapsing the roof), pits are blasted out and unit trains carry the ore back to the top or if shallow enough, by ore trucks. Gold and copper, being diffuse are commonly done this way, sometimes diamonds or other deposits created by weathering and concentration. (see Homestake Mine, Lead North Dakotaor Kennicot Copper Mine) both now closed.