Publications

Sets out the steps to establish a small scale coal mine in South Africa, from mineral rights and regulatory approvals through finance, mining and processing choices, marketing, and environmental management and closure. The information a new entrant needs sits in many separate places, so the guideline draws it together from practitioners rather than from any single published source.

Ants, termites, dung beetles and earthworms are known to improve soil health, but none had been deliberately applied as part of a mine reclamation strategy. Experimental and field scale studies asked whether dung beetles maintain their burial activity, and the soil services that follow, in soils typical of rehabilitated mine land, and set out recommendations for using them alongside existing methods.

Testing of 28 coal and coal-shale samples showed the coals to be more liable to spontaneous combustion than the shales, though reactive coal-shales still self-heat and pyrite in them speeds the process. Higher carbon, moisture, hydrogen, volatile matter and nitrogen with lower ash all raised proneness to self-heating, so proximate and ultimate analysis can serve as a screening tool.

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.

Sustainability in mining is still framed in neoclassical economic terms, measured by profit, shareholder value and growth, with social and environmental dimensions added in response to regulation. Six air quality and waste minimisation projects run over seven years were assessed against seven dimensions of the biosphere and fell well short. A collaborative model is proposed for a sector built on mining waste residues.

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.

Gas sampling on coal mine dumps found rehabilitation very effective at cutting emissions. Even incomplete rehabilitation held carbon dioxide below about 1 kg per square metre a year, against over 100 on unrehabilitated ground and as much as 7 000 where combustion was active, though burning areas were small. Sulphur oxides, nitrogen oxides, ammonia and methane were low.

Grazing pressure on the rehabilitated block ran at roughly three times the estimated carrying capacity. The sward was dominated by low quality grasses with a high proportion of bare ground and a raised erosion risk. Fenced exclosures over one year changed the abundance of a few species, but the vegetation showed no clear direction of recovery.