New technology for improving entry examination, thereby managing the rockfall risk in South African gold and platinum mines

Abstract

Rockfalls are responsible for more than 30 percent of the fatalities on South African gold and platinum mines, with associated costs and lost productivity. One of the most important activities in the mitigation of rockfalls is the entry inspection that occurs before workers enter a newly blasted workplace. It is also one of the more dangerous activities that takes place in a workplace. The CSIR has developed a sensor, called the electronic sounding device (ESD) that mimics the performance of a experienced miner, in order to determine whether loose rocks are present in the roof of the excavation, during the entry inspection. Tests of the ESD show a high degree of correlation with skilled human operators, allowing the device to be used where skilled operators are not available, or when skills are no longer viable due to hearing loss. Another sensor of loose rock is thermal infra-red imaging. This has also been proven to show the location of loose rock, but there is a practical problem in its routine implementation underground, due to its narrow field of view. This problem will be overcome using overlapping images that are stitched together. The combination of two sensors further increases the chances of correct decision making, and the visual sensing of the infra-red imager makes it harder to inadvertently miss inspecting risky areas. The combination can then be made available to unskilled workers through the addition of an augmented reality system based on a laser projector, that make the risk assessment system as easy to use as a torch. The ultimate aim is to combine both systems with positioning provided by an in-stope navigation system, in order to combine current data with historical results from a particular working place to further improve the estimate of risk.