Why are open-pit mines developed in benches?

Open-pit mines are developed in horizontal layers known as benches to facilitate organized extraction and manage the structural integrity of the mine. This method allows mining to occur on multiple levels simultaneously, with each bench top serving as a working level accessible via a system of ramps.1

Benches are essential for the following reasons:

• Operational Efficiency: Dividing a deposit into benches allows for systematic mining and the calculation of ore reserves in horizontal sections, which simplifies the creation of block models used to determine economic viability.12
• Structural Stability: The stability of pit walls is critical as a mine deepens. By designing benches and managing the overall pit slope, engineers can mitigate the risk of large-scale slope failures.1
• Economic Optimization: The geometry of these benches and the resulting slope angles directly impact the stripping ratio. Adjusting these angles allows operators to balance the cost of removing waste rock against the revenue generated from ore recovery.1

The height of these benches is typically determined by the type of deposit and the equipment in use, often ranging from 12 to 15 meters in large-scale operations.1