Open Pit Mining: Operational Methods and Safety Regulations in the U.S.
Open pit mining, a surface mining method, involves extracting ore or aggregate from a pit dug downwards from the surface, progressing level by level in steps known as benches. This method is predominantly used for non-coal materials, such as metal and aggregate deposits, with exceptions for certain near-surface, steeply dipping coal seams. The process begins at the surface and deepens over time, with pit walls designed as stepped benches to provide access for personnel and equipment. The number and dimensions of these benches, along with the pit wall angle, are critical for slope stability, a major safety concern. Mining engineers must ensure stability throughout the mine's operational life. Reclamation efforts, which involve returning waste to its original location, are typically deferred until mine closure to avoid obstructing access to lower ore levels. The pit's deepening continues until the cost of recovering the ore surpasses its market value, at which point operators may close the mine or transition...
