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A breakthrough ironmaking technology (1Tmk3) produces iron separated from slag by heating coal-iron ore composite pellets at temperatures as low as 1325C in about 10 minutes. Other researchers have studied the melting behavior, including the formation of a dense metallic shell separated from slag but the mechanism has not been yet fully understood. Exploring this knowledge gap was targeted in this study. The initial experiments included heating of composite samples at different temperatures and time intervals. Three coal types and two coal/ore ratios were investigated. By these experiments slag free iron production at low temperature and short time was confirmed. Coal type and coal/ore ratio were found to have a significant effect on melting behavior. The main series of experiments focused on the effect of slag composition mainly CaO and Si02, slag content and reaction time on the melting behavior. The main characterization methods included Optical Microscopy, Energy Dispersed X-ray Analysis (EDX), and simultaneous Differential Thermal Analysis (DTA), and Thermo Gravimetric Analysis (TGA). Despite most of the obtained results being qualitative, this study was successful in exploring some of the most important reasons behind the melting behavior of coal ore composites. It was revealed that the formation of a low melting point slag containing FeO in the core of the pellet and its exudation to the iron shell is responsible for the formation of a dense metallic shell. Densification of iron occurs by reduction of FeO in slag. The rate and extent of reduction is related to the physical properties of slag that in turn is influenced by slag composition. More basic slags tend to have higher rate of FeO reduction in slag. By reduction of FeO in slag, the interfacial tension of the remaining slag with iron increases and slag is separated from iron. / Thesis / Master of Materials Science and Engineering (MMatSE)

Numerous advanced coal-cleaning processes have been developed in recent years that are capable of substantially reducing both ash and sulfur-forming minerals from coal. However most of the processes involve fine grinding and use water as a medium; therefore, the clean coal products must be dewatered before they can be transported and burned in power plants. Unfortunately, dewatering is an expensive process, which makes it difficult to deploy advanced coal cleaning processes in commercial applications. Dry beneficiation technique is an alternate approach to solving this problem. Additionally, dry beneficiation process can be economically competitive and environmentally safe. Triboelectrostatic separation is one such technique and is very effective when applied to fine coal unlike other dry beneficiation techniques. This work involves the design (mathematical and physical) and testing of a novel triboelectrostatic separation process. / Master of Science

Fine coal constitutes a relatively small portion of a product stream in a coal cleaning plant. However, its processing cost is approximately three times higher than the cost of processing coarse coal. Therefore, many coal companies chose to discard the fines to refuse ponds, causing a loss of profit and creating environmental concerns. This problem can be solved by developing more efficient fine coal dewatering processes, since bulk of the cost associated with processing fine coal is due to dewatering. For this reason, Virginia Tech has developed new chemicals that can increase the efficiency of mechanically dewatering coal fines. To determine the performance of the novel reagents on fine coal dewatering, laboratory vacuum filtration and centrifugation tests were conducted. The utilization of the novel dewatering aids in the dewatering systems decreased the final moisture contents of the filter cakes to sufficiently low values. There was approximately 50% reduction in the cake moisture of many coal samples with the usage of the novel dewatering aids. The tests were performed on various coal samples from different coal preparation plants. This gave the advantage of testing the novel dewatering aids at many different conditions since each sample had its own characteristics. The vacuum filtration tests were extensively used to compare the efficiency of each novel reagent in dewatering. The best performing dewatering aids were determined and they were further utilized to analyze the effects of operational variables, such as; drying cycle time, cake thickness, vacuum pressure level and slurry temperature on dewatering. A statistical analysis was also performed to observe the effect of each factor quantitatively. The analyses were very useful in terms of determining the synergistic effects of these factors in dewatering of fine coal. The centrifuge tests were conducted to examine the efficiency of the novel reagents in a different dewatering application. The experimental results showed a significant improvement in centrifuge dewatering with the usage of proper coal sample. The moisture contents of fairly thick cakes decreased down to 5-10%. This outcome was very satisfactory since most of the dewatering aids commonly used in the coal industry were observed to increase the final cake moisture in centrifuge dewatering instead of decreasing it. Finally, surface chemistry analyses were performed on the coal samples and slurries to analyze the changes in the chemistry of the dewatering system in the presence of the novel dewatering aids. It was observed that there was a favorable improvement in the system chemistry, which was helpful in terms of decreasing the cake moisture content. These observations were also consistent with the results of the dewatering tests. The combined effect of the novel additives in decreasing the surface tension of the slurry and increasing the contact angle of the coal surface at the same time was concluded to be the reason for their significant performance as dewatering aids. / Master of Science

Sri Lanka is an island at the Indian Ocean with 65234 km2 and it has a power demand of 2000 MW. The hydro power was the main power source before year 2000, after maximum usage of hydro power Sri Lanka installed fossil fuel power plant to achieve the demand. Then the electricity price gradually increased due to higher increment of fuel price. As the solution for this higher price of electricity the government has to go to new profitable power source the coal power. Finally year 2011 Puttalam coal power plant 300 MW x 1 was installed with the hope of providing the low cost reliable energy supply to Sri Lanka and it will be extended to 300MW x 3 plan in year 2015. Therefore the puttalam coal power plant is the key power plant to the Sri Lankan power generation and it is expected to have the maximum output (base load) to the Power demand of Sri Lanka. Sri Lanka is a tropical country and it has two different weather seasons as rainy season and dry season. The puttalam power plant situated at Kalpitiya peninsula and it has normally dry weather condition, Months of April, October November and December have heavy rain condition (Meteorological Department, Sri Lanka, 2012). The puttalam coal power plant may not achieve full load because of high moisture content at rainy season. So this Thesis carried out to find the capability to achieve the full load with available plant, plant capacity by using different coal qualities. Then find the economical benefits and effect on the environment with the recommended coal for different seasons and also design a storage plan to coal storage at existing coal yard. Based on the historical data and the Meteorological department rain fall data and by doing a technical analysis the recommended coal type was selected and the capability of plant equipment capacity to the recommended coal to achieve the full load was analyzed. Then the coal storage plan was designed according to annual requirement of the different recommended coal and economical benefit was analyzed by considering last year cost for generated power and the generation cost, if recommended coal is used for last year. Finally flue gas analysis was carried out for the recommended coal to find the effect on the environment. The recommended coal for rainy season is with the heating value of 6600 kcal/kg and for dry season it is 6300 kcal/kg. The capacities of main boiler and other plant equipments are capable for the recommended coal to achieve the full load of the plant. Then the design of the coal storage plan was given under figure 4.2 and table 4.1. It was calculated that a profit of 3.932 million US$ can be achieved by using the recommended  coal for the last year and also when compared with the changing price of oil and coal it will be more profitable for the future. Because the oil price increases very rapidly and the increase in coal price is very low compared to the oil price. Finally the SOx and NOx emissions from recommended coal were analyzed and it was within the environmental limits because of the high quality emission reduction plant equipments.

Coal seams in the Waikato Coal Measures can vary significantly in thickness over distances of hundreds of meters to kilometers. Previously, the primary depositional controls on these variations have been inferred to be syn-depositional normal faulting and pre-depositional paleotopography. The data presented in support of these models are typically equivocal and which, if any, of these processes provide the principal control on the geometry and spatial distribution of coal seams in the Waikato Coal Region is uncertain. This study utilizes a large database of drill-logs, seismic-reflection lines and mine exposures in four areas (Huntly, Maramarua, North HuntlylWaikare and Rotowaro Coalfields) to test whether syn-depositional faulting and/or paleotopography influence coal seam architecture. These data were used to construct cross sections across faults and basement topography, which in turn, offer information on the relative timing of faulting and coal measure deposition, together with information on the spatial relations between seam thicknesses, faulting and paleotopography. Cross sections and isopach maps together with examination of spatial and temporal variations in fault displacements reveal that syn-depositional normal faulting had little or no impact on the deposition of the Waikato Coal Measures. Only in the Maramarua study area was any evidence found of fault control on coal measure deposition, with the Landing Fault accruing displacement between deposition of the Kupalrupa Seam and the end of coal measure sedimentation. The vast majority of faults in the Waikato Coalfield were, however, active following coal measure deposition. For example, the Foote, Kimihia and Pukekapia faults show evidence of displacement accrual, which commenced during deposition of the Mangakotuku Formation (37-35 Ma BP). The duration of this episode of faulting is difficult to determine, but may have ceased about 30 Ma ago. In addition, a number of faults (e.g. Foote Fault) display evidence oflate stage extension during the last 5 Ma. Given the lack of stratigraphic evidence for fault displacements during deposition of coal measures, it is suggested that the Mangakotuku and Waipuna basement scarps are erosional rather than tectonic features. Cross sections, together with structure contour and isopach maps in each of the four study areas examined, indicate that basement topography was the dominant control on the spatially variable accumulation of peat. These data show coal seams both thinning into, and away from, topographic lows. To account for this observation a model is proposed, in which peat accumulation is controlled by basement relief and sediment supply to parts of the depositional system. In the model it is postulated that the Waikato Coal Measures depositional system was a continuum between two end members. In one end member, with a high sediment supply, sediment is channeled into the lowest topographic areas and peat accumulates mainly on topographic highs. In the other end member, with little or no sediment supply, peat accumulates to its greatest thickness in areas of relatively low topography, in addition to on basement ridges. In the Rotowaro and North Huntly/Waikare study areas, the thickest peat developed on basement highs and the lows acted as a conduit for sedimentation. On basement highs, peat mires were largely sheltered from clastic sediment influx. In the Huntly East and Maramarua study areas, the thickest peat accumulated in basement lows, with comparable clastic sedimentation in highs and lows. The proposed model has application to other coalfields where peat accumulated on an undulating topographic surface and sediment supply was channelised. Prediction of coal seam thickness, as well as lithological types, is crucial in coal exploration and development. The methodology developed and employed in this study can be applied to other basins to access and model coal and clastic sediment distribution.

Chemical kinetic mechanisms governing the fate of coal nitrogen in the fuel-rich stage of a pulverized-coal staged combustion process were investigated. Emphasis was on determination of the effects of coal rank, temperature and stoichiometric ratios on the speciation and rates of destruction of nitrogenous species and correlation of coal data by a unif1ed mechanism. The relative importance of homogeneous and heterogeneous mechanisms during post-flame interconversion reactions of the fuel nitrogen pool was quantified. Experiments with doped propane gas and a high- and low-grade coals, burned under a variety of conditions in a 2 Kg/h downflow combustor, yielded timeresolved profiles of temperature, major (H₂, CO, CO₂, O₂ and N₂), nitrogenous (NO, HeN and NH₃) and hydrocarbon (CH₄ and C₂H₂) species. These profiles allowed global mechanisms describing the speciation and destruction of fuel nitrogen species to be explored, using predictive models of increasing levels of sophistication. Fuel nitrogen speciation varied significantly from coal to coal and depended on stoichiometric ratio and temperature, which were varied independently. A general correlation describing the destruction rate of NO was derived from data. This rate, which was first-order in both NO and NH₃, was generally valid for all coals and all conditions examined. Fuel nitrogen interconversion reactions, especially destruction of NO and HeN, was predominantly homogeneous, but no single elementary reaction was controlling. Temperature quench down the combustor is the origin of OH equilibrium overshoot. Expressions for estimating the OH equilibrium overshoot as a function of the axial temperature decay along the combustor were derived both empirically and kinetically from fundamental considerations using data from doped propane gas runs. These expressions, together with available literature values of gas phase rate coefficients, could adequately describe the post-flame NO and HeN profiles of coal and gas runs. HeN profiles in the far postflame zone of the coal flames are strongly influenced by the slow release of nitrogen from the coal residue. This devolatilization plays a critical role in supplying the HeN that drives the multistep process converting fuel N into molecular nitrogen.

Market efficiency and buyers' risk strategy in the Japanese coking coal import market are examined. The Japanese coal market is found to be inefficient, Japanese buyers traditionally have purchased coals from the United States at a high price and, since the second half of the 1980's, have paid the highest average price to Canadian producers. Given the abundant low cost Australian coals, this purchasing pattern does not meet the cost minimization criteria for efficiency. This is explained mainly by the buyers' risk management strategy. To more accurately examine price differentiation, the complexity of coal quality is considered first. A statistical method is used to estimate the quality premium as a cost component in price formation. Next a comparison of supply regions and a detailed investigation on market conduct is based on quality-adjusted prices, which are assumed to represent the prices of homogenous coals. Although various reasons are used by researchers to explain Japanese buyers power, this study finds vertical integration of the Japanese companies to be the most important factor creating that power. A detailed survey of vertical integration is made. Finally, a monetary value of the risk premium is estimated by using the partial elasticity of substitution. Total payments by Japanese coking coal buyers for risk premiums are estimated. These represent the extra dollars paid by the Japanese to US and Canadian coal producers for purchasing their coals instead of Australian coals.

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The South African coal industry produces a large quantity of coal per annum. The rejects from various unit operations, such as spirals, consist of fine coal that joins the plants tailings dam waste. As existing high quality resources become depleted, the need to improve recovery of this fine coal grows. This project investigates the use of a teetered bed separator (TBS); a hindered settling gravity concentration device for fine coal recovery. This device has proven successful in the United Kingdom and in Australian collieries for fine coal separation in the size range between 2mm and 0.3mm. It has also been used for decades as a classifying device for silica sand and tin. The TBS operates in the size range of water-only cyclones and spiral concentrators, and could potentially be used to separate a broader size range of coal fines so as to offer a lower footprint device for the fines recovery section of a plant. Spiral concentrators cannot always be operated efficiently at a separating specific gravity of lower than 1.6; a TBS may also extend the density range for separation and thus improve recovery. The objective of this project was to gain a full understanding of the TBS from fundamental particle interaction and develop a lab scale unit, which is capable of separation to about 0.1mm at optimum conditions. This involved the development of design parameters based on the various distributor plates and flow pattern modelling. The hydrodynamics of the separator were investigated using the Eulerian-Eulerian modelling approach of commercial CFD package, Fluent 6.1. Seven distributor plates of varying aperture size and geometric arrangement were considered. Coal and shale particles, sized between 2mm and 0.038mm with a specific gravity (SG) range of 1.2 to 2.0, were separated using the laboratory scale unit. The results of both the simulations and the laboratory tests were then compared. The simulations revealed that Plate 3 was the best option for implementation. It had an even upward velocity profile compared to the other plates, with minimum wall effects and disturbances. The upward water flow rate (teeter water) was varied experimentally and the composition of the teeter bed, underflow and overflow were analysed using 1.5, 2 and Smm cubic density tracers with an SG range of 1.2-2.0. Analysis of the partition curves of the distributor plates revealed that Plate 3 had the lowest Ecart Probable (Ep) and cut- point densities. The comparison of simulated results and experimental results show that the simulator could predict the distributor plate design with the lowest Ep in practical tests. The simulator could be beneficial when optimising an industrial scale unit, by allowing prediction of improved segregation patterns and thus separation efficiency. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.