Low-smoke Fuels: Test Work on Devolatilised Binderless Coal Briquettes

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.

Practical guidance for opencast operations covers early detection with low cost thermal cameras, prevention, and the treatment methods in current use: water sprays and cannons, sand cladding of highwalls and stockpiles, removal of burning coal by dragline, tipping into water ponds and the treatment of sinkhole areas. A three month full scale trial of sprayed fly ash as an antioxidant is reported.

Stockpiling degraded every soil property measured across four Witbank area mines. Clay content of topsoil and subsoil rose by 50 to 60 per cent, surface bulk density increased from stockpiling through to rehabilitation, and effective depth on rehabilitated areas was under 17 cm in most cases. Topsoil organic carbon fell by almost half and microbial species numbers dropped in the stockpiles.