As open pit mines come to the end of their lives and mining companies explore new mineral projects, the focus is increasingly on low-cost underground methods. Block caving has garnered interest in recent years as a viable alternative to conventional drill-and-blast and is viewed by many as the future of mining.
In a nutshell, block cave mining is a large-scale excavation method where ore and waste rock are extracted from below ground surface using large, vertically inclined tunnels. The technique has the potential to increase production rates and lower capital costs when compared with surface mining, while also significantly reducing surficial land impacts and disposal requirements.
Caving can be used to mine both inclined and flat deposits, with the inclination of the tunnels determining how quickly ore is extracted. Flat coal seams can be mined using a method called long wall mining where a thick wall of coal is progressively removed as a series of panels or blocks that may be up to four hundred meters wide and kilometers in length.
However, there are some important cave-mining considerations to be aware of; a cave in, or collapse of a geologic formation, structure or mine is a major safety concern that must be considered and addressed. In addition, the stress environment in a cave can be unpredictable and requires careful monitoring to ensure that any major structures are not adversely affected by blasting or water influx. Finally, good geotechnical information and reliable cost data are needed to design a successful cave mining operation.