Rotary Air Blast Drill Rig Top-of-Coal Detection While Drilling

Accurate control of overburden blasthole depth has the potential to significantly improve mine profitability through reduced coal loss and dilution. Ideally, blast holes would be drilled to a predetermined stand-off from the top-of-coal interface for every drilled hole. However, the current techniques for seam mapping from exploration holes do not provide an accurate surface profile at the local scale required for effective control, due to the spacing (typically 50m - 100m spacing) of exploration holes to map the coal seam location.

Advanced detection of the coal seam whilst production drilling allows for finer control of the blasthole depth and stand-off characteristics. This acuity promises to improve mine productivity and profitability through reduced coal loss and dilution. Ideally blast holes would be drilled to a predetermined stand-off from the top-of-coal interface for every drilled hole.

Mining3 and our partners have developed a novel approach in determining coal seam location while drilling in a rotary air blast (RAB) drill rig. By using geophysical measurement techniques, the top of coal detection system has been proven to be capable of mapping the location of the coal seam in a rotary air blast drill rig during routine drilling on a hole by hole basis. Furthermore, it has been proven that the system is capable of making measurements of the overburden during the drilling process. This information correlated well to drilling conditions and may prove to be useful for optimising blast design.

This report details the RAB drill rig top-of-coal detection while drilling phase 4 field trial at mine site, including the design, manufacturing, safety procedures, field trial results and development of advanced data processing. A literature review and update with further work of the theory from previous phases is also included.