The process involves stripping the surface away from the mineral that’s being excavated (usually coal). Soil, rock, and vegetation over the mineral seam is removed with huge machines, including bucket-wheel excavators.
This type of mining makes sense when the mineral is near the surface. If the ore is too far under the surface, the process of strip mining becomes impractical and needlessly damaging to the terrain.
The process has been around for centuries, with ancient cultures like the Greeks, Romans, and Persians mining for granite, marble and even salt. These pit mines continue to be enlarged until there is no more ore to mine or the overburden becomes too heavy.
These mines usually produce a vast amount of ore without the costly process of removing overburden — the ore is often in a large area and close to the surface. However, These type of mines are both dangerous to work in, and permanently alter the surrounding ecosystem.
Specialised Surface Mining Techniques
The process is best suited for retrieving mass amounts of minerals, usually coal, from mountain peaks. The process involves blasting the overburden with explosives above the mineral seam to be mined. This type of mining is used when the ore to be retrieved is 400 feet or deeper.
The process is mostly associated with gold mining. Floating dredges move up a water table. A scoop lifts material up on a conveyor belt, and the mineral is removed on board the barge. The unwanted material is then dropped back into the water table using another conveyor belt.
The process relies on machinery to collect ores from a “highwall”, or an unmined wall with overburden and exposed minerals and ores. It enable to retrieve ore from a wall that would otherwise be too expensive to clear of overburden in order to reach the ore at the edges of pit mines.