Bio-indicators in Stockpiled Coal Mining Soils in South Africa

A regional scheme to collect, treat and re-use mine water in the Upper Olifants River Catchment has merit, with the mines best placed to start it through a dedicated mine water company that brings in the water services authorities. Water legislation supports the scheme provided the regulator allocates mine water as a resource. Viability rests on the tariffs mines and water users pay.

Aircraft and ground based measurements at Kleinkopje Colliery showed spontaneous combustion to be a significant source of fine particles, with PM2.5 concentrations 91 per cent higher inside a combustion plume than outside it. Sulphur dioxide, nitrogen dioxide and carbon dioxide were also raised in plume, and benzene and toluene were detected. Average particle size was below one micron.

Dense medium cyclones on the fine coal fraction lifted product yield well above the spiral circuit they were compared against and gave closer control of product quality. Cut point density control proved the hardest part of running the plant, medium properties being critical. Magnetic separator capacity had to match the duty, and a basement was needed to contain and recover medium spillage.