The Poplar copper-molybdenum porphyry deposit, located 270 km west of Prince George, is centered in a late Upper Cretaceous differentiated calc-alkaline stock, which intruded Lower and Upper Cretaceous sedimentary rocks. The stock is capped by late Upper Cretaceous volcanic flow rocks. The lower Cretaceous Skeena Group consists of intermediate tuff, siltstone, and interbedded sandstone, which steeply dip to the south. This unit is unconformably overlain by a moderately sorted polylithic pebble conglomerate belonging to the Upper Cretaceous Kasalka Group. The Poplar Stock, which hosts mineralization, includes a border phase of hornblende quartz monzodiorite porphyry which grades in to a central biotite quartz monzonite porphyry. The stock is intruded by several post-ore dyke units, which include porphyritic dacite, porphyritic rhyolite, felsite, and andesite. Ootsa Lake porphyritic volcanic flow rocks overly the deposit, and are dacite in composition. Pre-ore, and post-ore rock units have been K-Ar dated, and are within analytical error of each other, having a mean age of 74.8 ±2.6 Ma. The deposit is covered extensively with glacial till and alluvial sediments. Therefore the majority of geologic information was obtained from logging the drill core from 34 diamond drill holes, twelve of which were logged in detail using a computer compatible logging format. Information logged in this manner was used in statistical studies , and for producing computer generated graphic logs and plots of various geologic parameters, along two cross-sections through the deposit. Alteration zoning at the Poplar porphyry consists of a 600 m by 500 m potassic alteration annulus which surrounds a 300 m by 150 m argillic alteration core. These are enclosed by 750 m wide phyllic alteration zone, which is itself bordered by a low intensity propylitic alteration zone. Phyllic alteration is defined by the occurence of sericite, and is the most abundant type of alteration present. Potassic alteration, recognized by the occurence cf secondary K-feldspar and/or secondary biotite, is most closely associated with chalcopyrite and molybdenite. At least two episodes of alteration are recognized at the Poplar porphyry. The first was contemporaneous with mineralization, following intrusion and crystallization of the Poplar Stock. This episode consisted of potassic alteration in the center of the deposit, which surrounded a 'low grade1 core, and graded out to phyllic and propylitic alteration facies at the periphery. The second alteration event took place after the intrusion of the post-ore dykes and consisted mainly of hydrolytic alteration of pre-existing alteration zones which were adjacent to more permeable centers, such as faults, contacts, and highly jointed areas. This alteration event is responsible for the anomalous central argillic zone, and the alteration of dykes, in addition to probably intensifying and widening the phyllic alteration halo surrounding the deposit. Chalcopyrite and molybdenite were deposited in the potassic zone at approximately 375° C and less than 250 bars, with relatively low oxygen, and relatively high sulfer, activities and moderate pH. As the potassic alteration zone was invaded by more acidic solutions feldspars were altered sericite and clay, and chalcopyrite was destroyed to form pyrite and hematite. Copper was removed from the system. Statistical studies include univariant one-way and two-way correlation matrices, and multivariant regression analysis. Statistical correlations generally support empirical correlations made in the field. These include positive correlations between various potassic alteration facies minerals, and these minerals and chalcopyrite and molybdenite. Multivariant regression analysis was used to determine which alteration minerals were best suited for indicating chalcopyrite and molybdenite. These minerals are quartz, biotite, magnetite, sericite, K-feldspar, and pyrite. Large error limits and poor correlation statistics in the results from these studies are attributed to deviations from normal distributions for all minerals. A possible cause of this may have been the multistage alteration events that the deposit has undergone. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

M.Sc. / This dissertation describes the N1 manganese ore bed at Gloria Mine in the Kalahari Manganese Field, Northern Cape Province. It also compares the ore bed at Gloria Mine with the correlative bed further to the south at Mamatwan Mine. The ore bed at Gloria Mine can be subdivided into ten texturally distinct zones that are laterally consistent throughout the mine lease area. The mineralogy and geochemistry of the various lithostratigraphic zones are described from two drill cores (GL28 and GL24), situated away from any known structural features or unconformities that could have affected the properties of the Ore. The ore in drill core GL28 has a mineralogical composition similar to that of typical Mamatwan-type ore described at Mamatwan Mine with braunite and kutnahorite as the main minerals. However, in drill core GL24 the ore has a very different mineralogical composition although it is texturally and geochemically rather similar to Mamatwan-type ore. The ore is composed of hausmannite, calcite and jacobsite and is apparently related to a post-depositional alteration event that did not effect Mamatwan-type ore in the Mamatwan Mine area. This altered ore is similar in composition to low-grade leastaltered manganese ores in the cores of fault blocks at Wessels and N’Chwaning Mines i.e. the area known for its hydrothermally altered high-grade manganese ores in the northern part of the Kalahari Manganese Field. In addition to the above, the N1 manganese ore bed at Gloria Mine also underwent ferruginisation close to certain joints and normal faults. No obvious alteration could be detected where the ore bed is unconformably overlain by Dwyka diamictite, nor associated with a thrust fault displacing the ore.

The global community has accepted Fischer Tropsch synthesis as one of the sustainable pathways to transportation fuels and chemicals due to the ever-depleting reserves of fossil fuels and its detrimental impact on the environment. However, the high capital investment and operating expenses associated with this technology have hampered its ability to compete with conventional petrochemicals. Some of the operating costs emanate from the choice of catalyst precursors and operational problems, which could lead to plant shutdowns. In recent times, few efforts have been made to explore cheaper FT catalysts to reduce operational costs, but the mechanical strength of solid FT catalysts, especially for pilot-scale fixed bed operations is not well represented in open literature. As a result, there is a high prevalence of mechanical failure of solid FT catalysts in pilot fixed-bed applications. In this study, we propose a scalable, Fischer Tropsch iron ore catalyst that is mechanically suited for fixed bed reactors to help address this issue. The catalyst development of the proposed iron ore catalyst involved the slurry phase impregnation of the precursor with copper and potassium and then shaping into spherical pellets with mass additions of 10%, 15% and 20% of bentonite(binder) on a rotating drum. There afterwards, the mechanical strength of each pelletized catalyst was tested using the single pellet crushing testing method (ASTM D 4179). These results were compared to the crushing strength of commercial spherical alumina to ascertain their suitability for fixed bed reactors. The most robust solid catalyst was the 10% binder iron ore pellets which recorded a single pellet crushing strength of 1833 kPa and was more than three times that of commercial spherical alumina and thus deemed apt for fixed bed reactors. A unique statistical approach was used to study the mechanical strength of the various binder combinations due to scattering in single pellet crushing strength data. The analysis revealed that the 10% binder iron ore pellets were most suited for laboratory FT runs and thus was tested for its catalytic performance. The FT runs revealed that the 10% binder iron ore catalyst had a CO conversion of 72.1 % and comparable to other similar iron-based FT catalysts reported in the literature. The proposed catalyst also showed a CH5+ selectivity of 83.2%, which was comparable the ones reported by other researchers. These findings provide a simple and cost- effect approach to upscale laboratory-scale FT catalyst designs to pre-emp its performance in pilot or industrial scenarios. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

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Page 20 missing from the thesis. / <p> This work was undertaken to evaluate neutron activation analysis as a technique for simultaneous determination of Ru and Os in sulfide minerals by counting the γ radiation of 97Ru and 103Ru, and the β^-radiation of 191Os and 193Os. The samples studied were collected from the Strathcona and Frood-Stobie Cu-Ni sulfide deposits of Sudbury. Sulfide minerals, including pyrrhotite, chalcopyrite, pentlandite and cubanite were separated from samples including representatives of both ore grade and non-commercial material. The minerals were analysed for Ru and Os to determine their concentration ranges in these sulfides, the degree of geochemical coherence of the metals in sulfides from both high grade ore zones and weakly mineralized rocks and their distribution between coexisting sulfides.</p> / Thesis / Master of Science (MSc)

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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 23 September, 2014, Johannesburg. / The Witwatersrand Basin has been mined for the last 125 years and is still one of the world’s largest producers of gold and has produced over 50 000 tonnes. However, uranium has also been mined as a by-product of gold from the Witwatersrand reefs, and over 150 000 tonnes have been produced. Over the past decades, the origin of this world class gold and uranium deposit has been debated and still remains controversial. Three main hypotheses were developed, and these are the placer, modified placer and hydrothermal models. In this study, the aims are: to evaluate how many generations of uranium-bearing minerals are in the Vaal Reef samples analysed from Great Noligwa, Moab Khotsong and Kopanang mines and to determine which model among the placer, modified place and hydrothermal best supports the emplacement of the uranium-bearing minerals in the reef. The Vaal Reef occurs in the lower parts of the Strathmore Formation of the Johannesburg Subgroup in the Central Rand Group of the Klerksdorp Goldfield in the Witwatersrand Supergroup. The Vaal Reef is split into three facies, namely the C, B and A Facies; the C and A Facies are the most economic facies at the three mines. The C Facies is well developed at Kopanang mine and the A Facies is well developed at both Moab Khotsong and Great Noligwa mines. Geochemical analyses revealed that the C Facies is enriched in uranium, carbon, sulphur and aluminium; this is due to the presence of uraninite, carbonaceous matter, pyrite and sheet silicate minerals, respectively. The A Facies, however, is more enriched in gold and quartz content, although high uranium, carbon and sulphur concentrations are found, they do not exceed the C Facies concentrations. Mineralogical investigations showed that uraninite, brannerite and uraniferous leucoxene are the uranium-bearing minerals present in the Vaal Reef samples. Uraninite is the main mineral and occurs firstly with detrital minerals such as pyrite, zircon and chromite in the quartz matrices; the second occurrence of uraninite is with the carbonaceous matter. Brannerite and uraniferous leucoxene are suggested to be formed from the breakdown of detrital uraninite grains interacting with Ti-rich minerals such as rutile. Unlike uraninite, brannerite and uraniferous leucoxene occur mainly in the C Facies matrix and occur as patchy or irregular-shaped minerals. The uraninite grains associated with the detrital minerals are mainly round in shape with sizes up to ~150 to 200 μm. This association with the detrital minerals suggests that uraninite was deposited together with the detrital minerals at the same time and that they were in hydraulic equilibrium with one another. Therefore, uraninite is also detrital in origin. The second generation of uraninite grains in the carbonaceous matter mainly show replacement and breakdown of uraninite by the latter, in many observations, uraninite grains are penetrated by the carbonaceous matter through cracks and are further fragmented into smaller grains. The sizes of these fragmented grains vary between 5 – 80 μm and have angular shapes, suggesting that they were first rounded and later broken down and replaced by the carbonaceous matter. A four-staged paragenetic sequence of the Vaal Reef samples was developed, and more importantly the paragenesis showed that the carbonaceous matter post-dates the deposition of uraninite. The three-dimensional microfocus X-Ray computed tomography (3D μXCT) was applied to the Vaal Reef samples and the main objectives were to visualise and analyse the uranium-bearing minerals in the Vaal Reef samples for their sizes, shapes and distribution with respect to other mineral components in the samples in 3D. The technique is currently unable to distinguish individual minerals from one another, especially when minerals have similar grey values as a result of close attenuation coefficients, mineral compositions and density. Mineral groups were identified following this similarity, include quartz and sheet silicates as one mineral group, all sulphides as another group and uranium-bearing minerals with gold as a third mineral group. The analysed uraninite with gold mineral group in the matrix, exhibited grains up to 200 μm in size which were round in shape, as observed in 2D mineralogical techniques. These observations support mineralogical observations acquired by conventional mineralogical techniques suggesting that 3D μXCT can be used to complement other mineralogical techniques in obtaining 3D information on minerals. However, 3D μXCT has limitations such as spatial resolution, partial volume effect and overlapping of mineral grey values. It is therefore, suggested that the technique not be used as an independent tool for mineral characterisation, but rather in support of the existing mineralogical techniques. The source area of the uraninite in the Vaal Reef of the Klerksdorp Goldfield is suggested to have been the hydrothermally altered Archaean basement granite bodies of the Witwatersrand Basin hinterland, from the Hartebeesfontein Dome northwest of the goldfield in particular. High UO2/ThO2 ratios, as determined by electron microprobe analyses (EMPA), support the notion that the uraninite grains are not a product of hydrothermal fluids, and furthermore high Pb contents showing that the uraninite grains are older than the age of the Witwatersrand deposition. In conclusion, the emplacement of uranium-bearing minerals in the Vaal Reef samples analysed in this study is best explained by the modified placer model.