Economic and Safe Extraction of Pillars and Associated Reserves Using Underground Mining Methods

Back analysis of 77 collapsed and 245 uncollapsed pillar cases showed that much of the scatter in pillar strength comes from differences between coalfields, so a single national formula is unrealistic. Seam specific formulae were derived for the major coalfields; Free State and KwaZulu Natal data remained too sparse. The lognormal safety factor distribution was retained.

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.

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.