Interpretation of the Waterberg Coalfield Airborne Geophysical Data – Final Report

Micro-gravity, electrical resistivity and time domain electromagnetics located the boundary between old workings and virgin ground, but no ground technique tested could resolve individual bords and pillars at the depths typical of the Witbank and Highveld coalfields. Airborne thermal infrared surveys worked well as a low cost regional reconnaissance tool for shallow sinkholes, fires and possible pollution plumes.

Electrical and electromagnetic ground surveys were run over a Waterberg profile with borehole logs and three dimensional seismic data as control, to test whether cheaper methods can match seismic reflection for locating coal and faults. Resistivity tomography at two electrode spacings, frequency and time domain electromagnetics, controlled source audio magnetotellurics and magnetics were all acquired. Results are preliminary.

A modified alkaline barium calcium process was tested on coal mine acid drainage, using calcium hydroxide neutralisation, hydrogen sulphide metal removal and barium carbonate sulphate removal. Gypsum formation during water treatment fell by 80 per cent, cutting the sludge sent to costly downstream processing to a fifth. Temperature, reaction time, reagent ratios and feed particle size affected thermal treatment of the sludge.