Additional Regional Gravity Survey of the Waterberg Coalfield and Regional Interpretation of the Gravity Geophysical Data

Relinquishment criteria follow from the agreed post-mining land use. The land use is the goal and the criteria measure whether it has been reached. The guideline sets out a framework for approving those criteria at each mining phase, from the initial environmental management plan through to decommissioning, and compares South African practice with Australian, Canadian and international guidance.

Nine bituminous coals from the Witbank, Waterberg and Soutpansberg coalfields all formed compacts without a binder, and the process worked better with coking coals. Reactive maceral content, free swelling index and Hardgrove grindability index governed briquette strength, with ash and kaolinite contents also contributing to bonding. Briquetting pressure, feed moisture and particle size distribution controlled the outcome.

Tonnage estimates for the remaining low phosphorus resource could not be produced, because the phosphorus analyses supplied by mining companies did not state what had been measured. Distribution trends were still mapped. Coal at or below 0.010 per cent phosphorus is widespread in the Witbank Coalfield, restricted to the far northwestern Highveld, and follows a northwest to southeast band in eastern Ermelo.

No operating full scale frictional ignition test facility was found anywhere in the world, and building one was judged expensive, impractical and unlikely to justify its cost against laboratory scale testing. Effort should instead go to small scale laboratory equipment using South African rocks, and to expanding geological data such as silica distribution and petrographic analysis.