Open pit mining is a method for mining minerals via an open pit in the earth. The method, which has been in existence for over a century, is currently the most widespread form of mining worldwide.
The sites where open pit mining takes place are diamond deposits created at the edges of cracks in the earth’s crust, following the penetration of blue kimberlites through these openings. Mining is conducted where the cracks widen to several hundred meters below the surface, thereby creating a funnel shape.
Open pit mining is conducted as follows: The miners detonate the funnel’s wide rim making its diameter reach up to a kilometer on the surface. The rocks and gravel collected during the excavation and controlled detonation are transported for crushing and screening, in the course of which the diamonds are extracted. From this stage on, the mining is conducted in depth, over a diagonal and graded course, until it reaches the narrow point of the funnel.
Excavation may be as deep as 500 meters below ground level. At this stage excavation is stopped because there are no diamonds in the funnel’s narrow part and any expansion of this section could cause collapse. At this point, the miner usually transfers to underground mining.
