Strip mining is a method used to extract coal reserves located relatively close to the Earth's surface by removing the soil and rock layers above the coal.
Fundamentally, strip mining operates by removing the overburden in rectangular blocks in plan view called pits or strips. The pits are parallel and adjacent to each other, allowing access to the coal seam beneath.
The Strip Mining Process
The process involves several key steps to access and remove the valuable resource:
- Preparing the Site: The area is cleared of vegetation and topsoil is often removed and stored for later reclamation.
- Removing the Overburden: This is the core of the method. Heavy machinery, such as draglines, shovels, and trucks, is used to excavate the layers of soil and rock covering the coal seam. As mentioned, this material, known as spoil, is removed from rectangular blocks or 'pits'.
- Forming Pits or Strips: These pits are created parallel and adjacent to each other. One strip is mined, and the overburden from the next adjacent strip is often placed into the mined-out pit.
- Extracting the Coal: Once the coal seam is exposed at the bottom of the pit, it is mined using specialized equipment.
- Spoil Handling: The way the removed overburden (spoil) is handled is a defining characteristic. Strip mining is fundamentally different from contour or area mining on how the overburden is displaced, called spoil handling. In typical strip mining, spoil is often placed in the previously mined-out strip adjacent to the one currently being worked.
- Reclamation: After mining in an area is complete, the land is typically reclaimed. This involves backfilling the pits, grading the surface, replacing the topsoil, and revegetating the area to restore it as close as possible to its original state or another beneficial use.
Key Characteristics
- Surface Mining: It is a form of surface mining, meaning the excavation occurs from the surface downwards.
- Overburden Removal: The primary step is the removal of the material covering the resource.
- Pit Configuration: Characterized by the creation of parallel and adjacent rectangular pits or strips.
- Spoil Displacement: Has a specific method of managing the removed overburden, which differentiates it from other surface mining types like contour or area mining.
In essence, strip mining systematically removes the top layers of earth in parallel sections to access shallow coal deposits, handling the removed material in a specific sequence to allow continuous operation.
