D.Phil. / Over a century gold exploration and extraction on the central Witwatersrand has left a legacy of mine residue deposits. Although there have been numerous complaints and claims of health effects associated with dust from these residue deposits, mostly these have been dismissed as mere nuisance. This study hypothesized that gold mine tailings on the Witwatersrand pose significant health risks to the nearby communities due to respirable airborne tailings material. Preliminary review of information on the tailings led to the insight that tailings source material and atmospheric properties at receptor sites are poorly characterized from the point of view of particle size-mass distributions. For years, routine monitoring of emissions from tailings storage facilities has been limited to sampling of dust fallout (settlable particles ≥ 30 μm). A suite of fifty four source samples (thirty-six slime, six newer slime and twelve sand) were collected from tailings storage facilities along the mining corridor covering deposits in the Carltonville area through to Springs. Size class characterization of source material was performed in the diameter range 0.05 μm to 900 μm using a Malvern® MS-14 Particle Analyser with 64 channels, from which the respirable (dp< 5 μm) and thoracic (dp < 10 μm) components were measured. Secondly, source materials were sieved (using a sieving cloth) in dp < 5 and < 10 μm fractions and the data derived was used in validating the size class results from the Malvern® MS-14 Particle Analyser before subjecting the samples to chemical analyses (elemental, mineralogical and radioactivity). Two years of continuous dust fall samples were collected in two different residential areas close to selected tailings storage facilities and subjected to similar size class characterization with the Malvern® MS-14 Particle Analyser. Further, continuous size-mass characterization of airborne aerosols was conducted in two different locations in the vicinity of tailings storage facilities with the Grimm® aerosol particle counter, in the diameter range 0.25 μm to 32 μm. The Grimm® aerosol particle counter was collocated with the MicroVol® PM10 filter sampler ambient monitor. The risk zones around selected tailings storage facilities were established by conducting dispersion modeling with American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD). The spatial evolution of tailings storage facilities and built-up areas is assessed using multiple aerial photographic images, covering four periods from 1952 to 2008. Overall, detailed spatial analysis was conducted and human inhabitants are now at greater risk than before. We have quantified the number of inhabitants living within the high-risk zone surrounding selected tailings storage facilities. The combined areas occupied by tailings storage facilities have increased from ~4 km2 (1952) to 10 km2 (2002); and residential areas ~4 km2 (1952) to 27 km2 (2002) within a buffer of 2 km. Population grew between 1952 and 2002 by a factor x29 at Crown Gold Recoveries; x43 at Durban Roodepoort Deep (from 1976); and x25 at East Rand Proprietary Mines.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:9362 |
| Date | 15 August 2012 |
| Creators | Ojelede, Matthew Ehigiator |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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