Economic and Safe Extraction of Pillars and Associated Reserves Using Underground Mining Methods

Mapping abandoned, inaccessible bord and pillar workings comes down to two options: borehole deployed laser or sonar scanning, or sensors carried in by unmanned vehicles. Drone mounted laser scanning for air filled voids and sonar carried by small submersibles for flooded workings were judged the most promising, but intrinsic safety, deployment and the risk of losing equipment still favour borehole methods for occasional use.