TECHNOLOGIES AHEAD OF THE MINING FRONT

Borehole information with associated mapping of mining excavations is currently used to model geological features ahead of the mining front. The accuracy thereof depends on the amount of drilling and mapping conducted. Single point data sets are gathered for a large area, which makes results unrepresentative of the orebody and associated structures within that block. The research team seeks to identify potential technologies that could enable access to more qualitative information ahead of the mining face.

The research team set out to determine if any advances have been made within the field of electrical resistance tomography (ERT) surveys. Their aim was to ascertain whether ERT methods can be used outside PGM potholes. The team investigated alternative tomographic approaches. They conducted an investigation of radio imaging technology (RIM) and possible uses within the mining industry. The team compared different in mine seismic technologies with specific reference to tunnel seismic prediction (TSP). The team conducted a numerical modelling study to analyse the performance of TSP, and they compared the analysis to 2D/3D surface seismic and passive seismic monitoring.

This research was commissioned to the CSIR and the University of the Witwatersrand. Researchers involved include CSIR principal geophysicist, Michael Van Schoor; geophysicist, Thabang Kgarume; University of the Witwatersrand seismologist, Prof Ray Durrheim; and University of the Witwatersrand director of the Seismic Research Centre, Dr Musa Manzi.

Tunnel-to-tunnel tomographic technologies such as electric resistance tomography (ERT) and radio imaging technology (RIM), as well as tunnel seismic profiling (TSP), have shown promise, which could enable one to obtain readily available information between two raise lines and potentially larger areas ahead of the mining front. An in-mine application of ERT involves deploying a line of electrodes along two adjacent tunnels, which was has been developed on the reef plane. More comprehensive datasets can be obtained to give a more accurate and detailed geological model. Previous proof-of-concept studies (PlatMine) demonstrated that tunnel-to-tunnel ERT could image disruptive features such as potholes and IRUPs. TSP could potentially play a role in characterising the structural integrity of the rock mass ahead of mining developments. In some parts of the world, TSP is currently being used in civil engineering tunneling projects.

This project has been completed.