Recently, an efficient resource model updating framework was proposed with the aim of improving the raw material quality control and process efficiency in any type of mining operation. This includes the integration of online-sensor measurements that are obtained during the production into the resource model. The concept has been applied in a coal mining environment with the aim of identifying local impurities in a coal seam and to improve the prediction of coal quality attributes in neighbouring blocks. The goal of this presentation is to demonstrate how the use of the resource model updating framework can provide added value for the mining industry. Both economical and environmental considerations are taken into account when the added value is investigated.

M.Sc. (Geography) / Coal mined in South Africa for the competitive international market, has to be selected to meet the many quality specifications of customers. This upgrading is done by washing the coal in a heavy medium separation plant. Marketable coal, discard and slurry are produced from this washing. Discard consists mainly of poor quality coal, carbonaceous shale and waste rock. Iron pyrite (FeS2) occurs in all of the above in higher concentrations than in the marketable coal. Both the carbonaceous materials and pyrites generate heat when oxidizing. If this oxidation is not arrested at an early stage on a discard dump and the temperature of the dump increases above BOoC, spontaneous combustion is quite likely. The South African Council for Scientific and Industrial Research (CSIR) has estimated that smouldering discard dumps in the Eastern Transvaal highveld region contribute approximately 400 000 tons of S02 per annum to the atmospheric pollution in that area. As a result, significant localized acid rain occurs, Louw (1990). The oxidation of iron pyrites to sulphuric acid, and the oxidation of other trace elements, is accelerated under the high temperature conditions generated by spontaneous combustion. Leaching of these oxidation products results in local groundwater and surface water contamination. This study describes different disposal technique and pilot study aimed at minimising the oxidation within the dumps. Slurry, which consists of discard and/or coal of less than 1 mm in diameter is co-deposited with discard in sequential layers of approximately 200 mm thick. This has resulted in reducing the permeability, porosity and air and water exchange within the dump. This in turn has led to a reduction in spontaneous combustion, pollution and costs. A visual increase in stability of the discard dumps, moisture content and operational ease of placement were experienced. The saleable value of the dump as a low value heat source is also preserved.

Low-grade coal, a poor source of energy, has long been regarded as waste material by the coal mining industry. Biological degradation of this coal material by ligninolytic fungal strains presents a viable strategy towards eliminating this unusable fossil fuel. To this end, a novel and patented bioprocess termed Fungcoal was developed. Fungcoal is a biological process utilised in the in situ treatment of waste coal and is based on the mutualistic relationship between the fungus Neosartorya fischeri and the graminaceous species Cynodon dactylon. The process facilitates the rapid conversion of waste coal into soil-like material that stimulates establishment of vegetation for eventual coal dump rehabilitation. While a number of in vitro studies have identified various fungal strains as efficient coal degraders, the mechanisms involved in the Fungcoal-stimulated degradation process have not been fully elucidated. Furthermore, implementation of Fungcoal at both pilot and commercial scale has not been achieved. Thus the objective of this work was to investigate Fungcoal as a bioprocess via examining the role of coal degrading fungi (CDF) and grasses as biocatalysts in coal biodegradation and for the self-cladding of waste coal dumps. Initially, waste coal degradation by N. fischeri, strain ECCN 84, was investigated, specifically focusing on the mechanisms underpinning the process. In vitro studies showed the addition of waste coal induced active fungal colonisation resulting in increased fungal biomass. Increased extracellular laccase (LAC) activity, occuring concomitantly with an increase in hyphal peroxisome proliferation, was also observed in the coal supplied fungal cultures. Analysis of the colonised waste coal revealed a time dependent reduction in the percentage weight of elemental carbon coupled with an increase in elemental oxygen. The results supported metabolism and degradation of waste coal by N. fischeri strain ECCN 84 and involvement of fungal extracellular laccase. The contribution of C. dactylon, a C4 grass species to in situ biodegradation of waste coal in the presence of coal degrading and mycorrhizal fungi (MF) was also investigated. Enhanced degradation of the waste coal into a humic soil-like material was observed within the rhizosphere. Analysis of the resultant substrate revealed an increased concentration of highly oxidised humic-like substances (HS). Fungi remained viable in the rhizosphere up to 47 weeks post-inoculation and cultivation of C. dactylon, indicating the resultant humic substance-rich rhizosphere provided an environment conducive for microbial proliferation and activity. Furthermore, humic substance enrichment of waste coal substrates supported germination and seedling emergence of several agronomic species including Zea mays (corn), Phaseolus vulgaris (bean), Pisum sativum (pea), and Spinacia oleracea (spinach). Use of various cladding materials to support coal biodegradation, by fungus-grass mutualism and rehabilitation of waste dumps was evaluated at commercial scale. While substantial physico-chemical changes were not evident in the absence of cladding or where waste coal was used as cladding material, successful establishment of grass cover and diversity was achieved within three hydrological cycles on dumps cladded with weathered coal. Work presented in this thesis successfully demonstrates the degradation of waste coal by N. fischeri. The biodegradation process included enhanced extracellular LAC activity coupled with increased 3 waste coal oxidation. Increased HS concentration of waste coal substrate supported germination and early seedling establishment of several agronomic species. At commercial scale a co-substrate in the form of carbon-rich weathered coal was essential to support fungus-grass mutualism and Fungcoal-induced rehabilitation. These findings support the developed Fungcoal concept and the underpinning rationale that the phyto-biodegradation of waste coal indeed depends on the mutualistic interactions between grass root exudates and the ligninolytic and mycorrhizal fungi. Taken together, these findings provide practical evidence of the contribution of fungi and grasses as mutualists in the biodegradation of waste coal and sustainable rehabilitation of waste coal dumps

The development of coal biotechnology, using hard coal as a substrate, has been impeded by its low reactivity in biological processes. As a result, the more successful application studies have focused on lignitic soft coals. However, new studies have reported using biologically or geologically oxidized hard coal as a functional substrate option for bioprocess applications on a large scale. This study undertook a preliminary investigation into the feasibility of environmental applications of coal biotechnology using oxidized hard coal substrates in both anaerobic and aerobic processes with carbon dioxide, sulfate and oxygen as terminal electron acceptors. A preliminary characterization of the oxidized hard coal substrates was undertaken to determine and predict their viability and behavior as electron donors and carbon sources for environmental bioprocess applications of direct interest to the coal mining industry. Both biologically and geologically oxidized coal substrates showed loss of up to 17% and 52% carbon respectively and incorporation of oxygen ranging from 0.9 – 24%. The latter substrate showed greater loss of carbon and increased oxygenation. The biologically and geologically oxidized hard coal substrates were shown to partition readily into 23% and 32% organic humic acid, a 0.1% fulvic acid fraction and 65% and 59% inorganic and humin fractions respectively. These organic components were shown to be potentially available for biological consumption. In the unmodified hard coal substrate, partitioning was not observed and it did not perform as a functional substrate for any of the bioprocesses investigated. Where carbon dioxide was used as a terminal electron acceptor, methane production ranging from 9 – 26 mg CH4.g substrate-1 was demonstrated from both oxidized coal substrates. Geologically oxidized coal produced 30% more methane than biologically oxidized coal. Methane yields from the geologically oxidized coal in the presence and absence of a co-substrate were 5 – 13-fold higher than previous studies that used hard coal for methanogenesis. Based on these results, and that the development and optimization of the biological oxidation process is currently ongoing, further applications investigated in this study were undertaken using geologically oxidized coal. It was shown using pyrolysis gas chromatography mass spectrometry that the methanogenic system was dependent on the presence of an effective co-substrate supporting the breakdown of the complex organic structures within the oxidized hard coal substrate. Also that the accumulation of aromatic intermediate breakdown compounds predominantly including toluene, furfural, styrene and 2-methoxy vinyl phenol appeared to become inhibitory to both methanogenic and sulfidogenic reactions. This was shown to be a more likely cause of reactor failure rather than substrate exhaustion over time. Evidence of a reductive degradation pathway of the complex organic structures within the oxidized hard coal substrates was shown through the production, accumulation and utilization of volatile fatty acids including acetic, formic, propionic, butyric and valeric acids. Comparative analysis of the volatile fatty acids produced in this system showed that geologically oxidized coal produced 20% more of the volatile fatty acids profiled and double the total concentration compared to the biologically oxidized coal. The use of geologically oxidized hard coal as a functional substrate for biological sulfate reduction was demonstrated in the neutralization of a simulated acid mine drainage wastewater in both batch and continuous process operations. Results showed an increase in pH from pH 4.0 to ~ pH 8.0 with sulfide production rates of ~ 86 mgL-1.day-1 in the batch reactions, while the pH increased to pH 9.0 and sulfide production rates of up to 450 mgL-1.day-1 were measured in the continuous process studies using sand and coal up-flow packed bed reactors. Again, the requirement for an effective co-substrate was demonstrated with lactate shown to function as a true co-substrate in this system. However, a low cost alternative to lactate would need to emerge if the process was to function in large-scale commercial environmental treatment applications. In this regard, the aerobic growth and production of Neosartorya fischeri biomass (0.64 g.biomass.g SOC-1) was demonstrated using oxidized hard coal and glutamate as a co-substrate. Both can be produced from wastes generated on coal mines, with the fungal biomass generated in potentially large volumes. Preliminary demonstration of the use of the fungal biomass as a carbon and electron donor source for biological sulfate reduction was shown and thus that this could serve as an effective substrate for anaerobic environmental treatment processes. Based on these findings, an Integrated Coal Bioprocess model was proposed using oxidized hard coal as a substrate for environmental remediation applications on coal mines. In this approach, potential applications included methane recovery from waste coal, use of waste coal in the treatment of acid mine drainage waste waters and the recovery and use of humic acids in the rehabilitation of open cast mining soils. This study provided a first report demonstrating the use of biologically and geologically oxidized hard coals as bioprocess substrates in environmental bioremediation applications. It also provided an indication that follow-up bioengineering studies to investigate scaled-up applications of these findings would be warranted.

Near-density material is material with similar densities to that of the chosen cut-point density during the separation process of coal into product and discard. The problem is usually classified as a beneficiation problem and not as a reserve problem. To overcome the risk associated with near-density material in the beneficiation process, the constraints of the separators must be merged with the constraints of the coal resource. The problems caused by the presence of near-density material in the beneficiation process of raw coal to a certain percentage ash product, are commonly associated with South African coals. Near-density material is caused by the presence of finely dispersed mineral matter in the coal that can not be separated from the coal by current liberation methods. The mineral matter referred to is directly linked with the original depositional environment of the coal. The depositional environment of coal formation determined the ash, the mineral matter present and the distribution within the coal matrix. A closer look at the ash distribution reveals that all types of coal, irrespective of depositional environment, has intrinsic ash content grouped around a certain percentage and that the amount of near-density material present in the beneficiation process depends on the percentage ash, in the clean coal product, required. As the ash distribution is the controlling factor on near-density material, any external factor that effects the ash distribution will affect the coal’s washability characteristics. There are various methodologies to define a coal’s amenability to being washed to a certain clean coal ash product. All of the methods generate an empirical value of near-density material or the coal’s “difficulty” in being washed. All of these methods have their advantages and disadvantages, but the method used is of no consequence if the information is not applied correctly to the coal resource or reserve. At Leeuwpan Coal Mine a risk matrix is used to relate the values from near-density material calculations to the coal reserves. The risk values from the matrix is incorporated into the mining blocks so that during the mine planning phase the risk of near-density material can be quantified and minimized. At Leeuwpan Coal Mine the application of the risk matrix into the planning and exploitation of the coal seams indicated that through resource/reserve management quality problems, due to near-density material can be minimized and that yield can then be optimized. The optimisation of yield leads to a financial gain that increases the value of the reserves. Therefore by pro-active planning and a good understanding of the resource/reserve the risk associated with near-density material can be managed. / Dissertation (MSc)--University of Pretoria, 2009. / Geology / unrestricted

The coalfields of South Africa contain numerous dolerite intrusions, which are believed to have affected the quality of the surrounding coal by a thermal process, controlled by the size of the magmatic body. Data gathered from a working coalfield in Secunda, South Africa, suggest that the relationship between intrusive sills and coal is complex and factors other than intrusion width must be considered in relation to the contact metamorphic effect. The study area contains multiple dolerite intrusions of Karoo age, separated according to their geometric relationship to the local coal seams. Three intrusions were selected for detailed study. The three dolerite bodies, namely the DO4, DO8 and DO10 dolerites, occur as sills intruded close to the main coal seam of the area. The dolerite sills have identical mineralogy and can only be distinguished through textural variations in thin section. Coal quality data was obtained from Sasol Mining Secunda and used to investigate the presence or absence of a change in coal quality relative to dolerite proximity. Reduction in coal quality was defined using three main proximate analysis values, termed Ash, Volatile content (Vols) and Dry Ash Free Volatile (DAFV) in the coal industry. These parameters were used to determine the extent of any effect deleterious to coal quality induced by the intrusion of the dolerite sills. The resultant investigation showed no correlation between the position and thickness of the dolerites, and a change in coal quality (as measured by proximate analysis). In the absence of a linear relationship between coal quality and dolerite proximity, two processes are proposed to explain the absence of the contact metamorphic effects expected from previous studies: -Dolerite emplacement dynamics may influence the size of the metamorphic aureole produced by an intrusion, and invalidating intrusion size as a measure of thermal output, - Hydrothermal fluids mobilised by the dolerite intrusions, either from the country rock or the intrusion itself may percolate through the coal and act as the metamorphic agent responsible for changing coal quality, by dissolving the volatile components of the coal and transporting them to other locations These two processes are sufficient to explain the lack of a clear “metamorphic effect” related to the dolerite intrusions. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Geology / unrestricted

No description available.

The Albian Lower Skeena Group in the Telkwa coalfield comprises more than 500 metres of conglomerate, sandstone, siltstone, mudstone and coal deposited during two regressive/transgressive cycles. The stratigraphic sequence is divisible into four lithostratigraphic units. The basal unit, Unit I, may be more than 100 metres thick and comprises conglomerate, sandstone, mudstone, coal, and seat earth. Conglomerate and sandstone are composed dominantly of chert and volcanic rock fragments, and mudstones are kaolinitic. Unit I was deposited in a fluvial environment on an eroded volcanic basement. Gravel and sand were deposited in braided channels and bars, and mudstone accumulated in floodplains. Coal formed in poorly drained, peat-forming backswamps. In the northern part of the study area, coal seams thin and split, a result of periodic flooding of peat swamps with sediment-laden water from nearby streams. Deposition of Unit I ended with a marine transgression and deposition of Unit II. Unit II consists of up to 140 metres of silty mudstone, bioturbated or cross-bedded, chert and muscovite-rich sandstone, and rare thin coaly mudstones deposited in a deltaic/shallow marine environment. Sand was deposited in distributary channels and mouth-bars, mud accumulated in bays, and thin discontinuous peat beds accumulated in local salt marshes. There is structural evidence for the presence of an unconformity within Unit II, but palynological and paleontological data suggest that the strata are all similarly aged. Unit III averages 90 metres thick, and comprises bioturbated or rippled, chert and muscovite-rich sandstone, siltstone, carbonaceous mudstone and thick, laterally extensive coal seams deposited in a variety of low-energy, paralic environments. Sand and mud were deposited and biogenically reworked in tidal flats, and siltstone accumulated in a restricted, nearshore marine environment in the eastern edge of the study area. Peat accumulated in freshwater coastal marshes which periodically prograded over tidal flats. All but the lowermost coal seams pinch out eastward into restricted, nearshore marine sediments, and the ash content of the coal increases toward the margin of the seam. Locally, the sulphur content of the coal is high, reflecting occasional inundation of the fresh-water swamps by brackish water. High sulphur coal contains relatively more pyritic sulphur and less organic sulphur, compared to low-sulphur coal. Unit IV is at least 150 metres thick and is composed of chloritic, green sandstone overlain by silty mudstone, deposited in a marine environment. The basal sandstone is a transgressive lag deposit, and silty mudstone, the predominant lithofacies, was deposited in a nearshore, shallow marine environment. The provenance of the sediments in the Telkwa coalfield changes from the base to the top of the stratigraphic section. Conglomerate and sandstone of Unit I contain an abundance of volcanic clasts and grains, locally derived from underlying and surrounding volcanic rocks of the Jurassic Hazelton Group, which were uplifted as part of the Skeena Arch and subsequently eroded and reworked. Sandstones of Units II, III and IV, which contain much less volcanic-derived material and an abundance of mica flakes, were derived from high-grade metamorphic rocks in the Omineca Belt. Chert grains are abundant throughout, reflecting continued clastic influx from the Pinchi Belt-Columbian Orogen. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

>Magister Scientiae - MSc / Coal-fired power stations produce large volumes of coal combustion residues (CCRs), which are disposed of in hold ponds or landfill sites. These ash storage facilities are limited in space and are approaching the end of their capacities, thus additional land is required for extensions. If new land is not sourced, power plants will be forced to cease operations, resulting in increased expenditure costs and environmental liability. A proposed disposal solution is to backfill opencast coal mines with CCR monoliths. However, there is limited knowledge on the hydraulic behaviour of CCRs in an opencast coal mine environment. This leads to an inability to assess this applications feasibility and determine whether this activity will have a positive, negligible or negative effect on groundwater quality. This study aims to address this gap in knowledge by assessing the flow and transport properties of CCRs under numerous theoretical backfilling conditions.

The coal mining industry has played a significant role in the development of the South African economy. Coal supplies about 70% of South Africa's primary energy and is likely to remain the country's major source of energy despite the increasing trends towards renewable energy. Even though the industry has significantly contributed to the development of the country, it has also caused significant impacts on the environment with concomitant socio-economic impacts. Historically, once a coal measure was exhausted, mining companies would cease production and abandon the mines without proper rehabilitation of the environmental degradation caused by their mining activities. As a result of this, the South African Government introduced mining and rehabilitation legislation to mitigate the environmental and associated socio-economic impacts of mining. Rehabilitation guidelines for opencast coal mines were developed to provide detailed guidance for achieving successful and sustainable rehabilitation, to mitigate pollution post-mining. Despite the more stringent legislative framework and the development of international standard rehabilitation guidelines, successful mine rehabilitation remains a challenge. This research project aims to develop a better qualitative understanding of the status, challenges, gaps and opportunities pertaining to current rehabilitation practices in the case of opencast coal mines in the Mpumalanga Province of South Africa, and in so doing, establish the contributing factors of unsuccessful rehabilitation. The dissertation draws on a comprehensive review of published literature and an analysis of semi-structured interviews with rehabilitation experts. The study found that the current rehabilitation practices in the Mpumalanga opencast mines are not to the standard required by the legislative framework nor prescribed by rehabilitation guidelines. As such, the current rehabilitation practices are not yielding successful and sustainable rehabilitation. According to the findings, the rehabilitation practices are hampered by physical and non-physical systemic challenges that thwart the achievement of successful rehabilitation. The study analysis shows that shortcomings in the application and enforcement of the legislative framework contributes to the legislation not achieving its intended objectives as well as the development of other physical and non-physical systemic challenges that hamper the achievement of successful rehabilitation.