Thesis (MSc(Geography and Environmental Studies))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: In an area where mining activities dominate, there are likely to problems that need effective environmental management approaches, which can be facilitated through legislation and environmental management systems (EMS). The Great Dyke in Zimbabwe is a strategic economic resource with significant quantities of chrome and platinum. Chrome mining occurs across the whole length of the Great Dyke with most of the operations under Zimasco claims. Zimasco mining operations fall into two categories: the organization‟s own claims operated in its own right and claims that are leased out to a second party forming a tribute system from which tributor miners produce chromite ore exclusively for Zimasco. This study examines the environmental management approaches used by Zimasco operations, in particular the National Occupational Safety Association (NOSA) Integrated Five Start System, in order to identify the usefulness of EMS in the mining industry. Firstly, the current environmental impacts associated with the mining activities were identified and problem areas highlighted, after which environmental management approaches linked to national legislation were examined in terms of their contribution towards sound environmental management. A legal compliance checklist was carried out on the existing mines to assess levels of compliance to standards stipulated in the Environmental Management Act Chapter 20:27. This was followed by questionnaire surveys used for impact identification and the data was analysed using the aspect and impact analysis matrix. Underground mines with effluent discharges were assessed by means of an effluent analysis as a way of determining the effectiveness of the approaches on the mines. Recommendations for changes were made following a Strength Weaknesses Opportunities and Threats (SWOT) analysis of the approaches and system. Major environmental problems highlighted included unattended waste rock dump and pits as well as dissolved substances in effluent discharge. Although evidence of compliance to environmental legislation for the mining operations was found at administrative level, this was often not executed in operation. Limited hazards were observed in effluent discharge from mines under full implementation of the EMS. It is recommended that all mining operations need to be covered by an EMS system for improved environmental management and sustainable development. Effective implementation of legislation and EMS on the ground provides a better platform for sound environmental management. / AFRIKAANSE OPSOMMING: In 'n area waar grootskaalse mynbou aktiwiteite die omgewing kan affekteer word effektiewe omgewingsbestuur benodig. Die Groot Dyk in Zimbabwe is 'n strategiese ekonomiese hulpbron met groot hoeveelhede chroom en platinum. Chroom word grotendeels onder Zimasco kleims langs die Groot Dyk ontgin. Zimasco mynbedrywighede val in twee kategorieë: eerstens eie kleims wat direk deur Zimasco bedryf word, en tweedens kleims wat aan 'n tweede party verhuur en bewerk word en chroom eksklusief aan Zimasco lewer. Die omgewingsbestuursbenadering wat deur die Zimasco mynbedrywighede gebruik word, veral die NOSA Geïntegreerde Vyfster Stelsel, is bestudeer om vas te stel of omgewingsbestuurstelsels (OBS) effektief kan wees in die mynbedryf. Eerstens is die huidige omgewingsimpte veroorsaak deur mynbedrywighede geïdentifiseer en probleemareas uitgelig. Verder is die omgewingsbestuursbenadering in die lig van nasionale wetgewing bestudeer om die bydrae tot gesonde omgewingsbestuur toe te lig. 'n Lys is opgestel waarin die mate waartoe geselekteerde myne aan bestaande wetgewing voldoen bepaal is. Vraelyste is ook gebruik om die omgewingsimpak te identifiseer en data is met behulp van die aspek en impak analise matriks geanaliseer. 'n Afvoeranalise is op ondergrondse myne gedoen ten einde die effektiwiteit van omgewingsbestuursbenadering op die myn te bepaal, terwyl 'n SWOT analise van beide die benadering en die NOSA Vyfster Stelsel uitgevoer is met die oog op aanbevelings. Die belangrikste omgewingsimpakte langs die Groot Dyk sluit in: afvalrotshope, kuipe en slote vanaf oppervlakbedrywighede asook opgeloste afval in afloop vanaf ondergrondse myne. Bewyse van voldoening aan omgewingswetgewing is wel gevind in myndokumentasie, maar nie altyd in die praktyk nie. Laer vlakke van toksiese uitvloeisel vanaf myne waar OBS geïmplementeer is, is bewys van die suksesvolle gebruik van „n geïntegreerde OBS. Alle mynaktiwiteite moet ingesluit word in „n OBS stelsel om beter omgewingsbestuur en volhoubare ontwikkeling te verseker. Effektiewe implementering van wetgewing en OBS op die laagste vlak in mynaktiwiteite bied 'n beter platform vir gesonde omgewingsbestuur in die mynbedryf.

Although soils developed from ultramafic parent materials have significance to agriculture, ecology and health, their bio-geochemistry is poorly understood. The mineralogical and bio-geochemistry of soils formed from the ultramafic parent materials of the Great Dyke, Zimbabwe and Gillespie County, Texas was investigated. The objectives were to determine the mineralogical and bio-geochemical properties of the soils in order to assess the potential impact and challenges to agriculture, and environmental quality. Soil samples were taken from the crest, shoulder, footslope and the toeslope. Chemical analyses were performed by nuclear and spectroscopic techniques. Mineral characterization was conducted by x-ray diffraction (XRD) and spectroscopic techniques. Microbial whole-community structure was determined by the fatty acid methyl esters (FAME) technique. The results indicate wide chemical and mineralogical compositions among the studied sites. The soils contain relatively high concentrations of heavy metals (some sites contain Cr(VI)), but low levels of K and Ca. The highest concentrations of trace metal were associated with chromite, Fe oxides and serpentinite. The concentrations of Mg were higher than those of Ca and varied between Zimbabwe and Texas soils largely due to the parent materials. Unique to these soils is the occurrence of talc, serpentine, chlorite, Fe-rich smectite, amphiboles, pyroxenes, Fe and Cr oxides in relatively large amounts. These soils also lack micas and have neglible amounts of kaolinite and feldspars. Palygorskite and serpentine occurred in specific soil horizons and at specific landscape positions. FAME profiles indicate that the soil microbial community structure is predominantly bacteria and fungi (including arbuscular mycorrhiza fungi) at each landscape position across the transect. Biomarkers for actinomycetes were undetectable. The proportions of Gram-positive bacteria were higher than those of the Gram-negative bacteria. Very low levels of nutrients (Ca and K), higher Mg/Ca molar ratios, and the relatively high concentrations of heavy metals in these soils impact agricultural productivity. High concentrations of heavy metals, the presence of the Cr(VI) as well as its great potential to form in these soils might impact microbial activity and environmental quality. The occurrence of fibrous minerals (e.g serpentine and amphiboles) in these soils will likely impact human health.

Previous mineralogical investigations (QemSCAN) performed on all effluent flotation streams of Mimosa mine (Zimbabwe) indicated the presence of appreciable amounts of platinum group minerals (PGMs), which are not recovered. Most, generally in excess of 70%, of the liberated PGMs in these streams belonged to the Pt-Pd-Bi-Te class in all the samples investigated. In the first part of this work, electrochemical investigations, electrochemically-controlled contact angle measurements and Raman spectroscopy have been employed to investigate the interaction of ethyl xanthate with Pd-Bi-Te and PtAs2. Impedance measurements showed lower capacitance values in solutions containing KEX indicating the formation of a continuous surface layer. Anodic and cathodic polarization diagrams show the mixed potential to be higher than the reversible potential of the xanthate-dixanthogen equilibrium reaction, hence the formation of dixanthogen on the surface is possible. Electrochemically controlled in situ Raman spectroscopy has confirmed the co-presence of xanthate with dixanthogen indicating that xanthate retains its molecular integrity when it adsorbs on the surface of the Pd-Bi-Te. The result of this investigation has shown dixanthogen to be present on both the minerals (PtAs2 and Pd-Bi-Te) when the surfaces are anodically polarized. Chemisorbed xanthate could be identified within 120 seconds yielding a hydrophobic surface as indicated by electrochemically-controlled contact angle measurements. Maximum contact angles of 63o were measured in the case Pd-Bi-Te. As a result the mineral surface is expected to be hydrophobic and a lack of collector interaction with the mineral is not the reason for low PGM recoveries experienced. Secondly, the flotation recovery of synthetically prepared Pd-Bi-Te was compared with that of chalcopyrite (a typical fast-floating mineral) and pyrrhotite (a typical slow-floating mineral), with microflotation tests. These indicated Pd-Bi-Te to be a fast-floater with flotation rates exceeding that of chalcopyrite. Predicted flotation rate constants (from the Ralston model) were significantly lower for small particles (with diameters similar to those lost to the effluent streams) compared with those of particle with intermediate sizes. This supports the suggestion that losses to effluent streams are caused by particle size effects. / Thesis (PhD (Metallurgical Engineering))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted