Technical Review of Thin Seam Clearance Systems for Rom Coal

The fine coal dense medium pilot plant was rebuilt at South Witbank Coal Mine and run on fine coal, with tests covering single, double and three stage processing, the effect of recirculating load, magnetite size and losses, separation efficiency and continuous operation. The fast screen could not deliver the required capacity and was replaced by dewatering cyclones to deslime the feed.

Finite element simulation reproduced the rapid collapse of bord and pillar workings in the 2 Seam at a Witbank colliery, showing that progressive pillar deterioration triggers snap through of a strong sandstone plate in the overburden. Too little was known about the chosen collapse to back out a real pillar safety factor, so the calibration goal was not met.