Abstract:
Borehole radar is a short-range, high-resolution geophysical technique that can be used to delineate the position of the Merensky platinum reef in underground mines situated in the Western Bushveld Complex. In this study, borehole radar is used in reflection mode from four boreholes drilled sub-parallel to the expected position of the Merensky Reef within an underground mining block bounded by two cross-cuts and a haulage. This study relates the stratigraphic column at Amandelbult Section to borehole radar reflectivity. The radar illumination line coordinates produced along the Merensky Reef surface are used to construct a three-dimensional surface of the reef within the defined mining block. The geophysical interpretation presented here shows how a slump in the Merensky Reef, called a pothole, is imaged using borehole radar. This study analyses the increase in geological confidence related to the improved delineation of the elevation of the Merensky Reef. The financial impact of using borehole radar to delineate this pothole is analysed at the various mining steps, namely: orebody definition, mine planning, mine development, ore extraction and ore processing. The information gained by conducting borehole radar is compared with the information acquired using only standard geological drilling. This study concludes that the application of borehole radar significantly increases the confidence in the geological model prior to mining. Conducting borehole radar prior to mining improves mine planning and development, ensures that less waste is mined, facilitates the effective deployment of labour crews, prevents waste being sent to the processing plant and avoids deferring income until a later date. Recommendations are made on how to plan for and include borehole radar in the mining process.
