Tesi sul tema "Coal"

In order to reduce expensive coke usage, blast furnace operators inject coal to replace a portion of the coke. However, the use of some injection coals can result in blast furnace instability and lowered permeability. This thesis is concerned with the injection of coal under entrained flow, high heating rate (104-106 °C/s) blast furnace conditions, namely the possibility of coal particle agglomeration via the use of caking coals. Methods of mitigating agglomeration via blending and pre-oxidation are tested, whilst the resultant performance implications of agglomerated coal chars are considered and analysed. A drop tube furnace (DTF) was used to experimentally test coal injection under conditions that are applicable to the blast furnace 'hot blast' region. Relatable DTF parameters include an operating temperature of 1100°C, and heating rate of 104 °C/s. Four industrial injection coals with varying volatile matter and caking properties were tested at both granulated and pulverised particle size specifications. It was found that coals defined as 'caking coals' showed consistent agglomeration during DTF injection, a potentially problematic effect regarding blast furnace injection. Agglomeration percentages (as defined by sieve classification) for the industrially problematic MV4 coal were 11% and 23% for the granulated and pulverised samples respectively. Blending of whole coals was effective in reducing the amount of agglomerated material in the char, as was sample pre-oxidation prior to injection. Regarding performance, agglomerated chars had greater combustion performance and gasification reactivity than the non-agglomerated samples. With agglomeration shown to be present under high heating rate conditions at temperatures akin to the blast furnace hot blast, it is concluded that agglomeration is a possibility during blast furnace injection. However, due to differing feed systems between the DTF and blast furnace, the precise form and extent of agglomeration in the blast furnace remains uncertain. Based on char combustion and gasification analysis, chars characterised by fine agglomerated material are not likely to be problematic for blast furnace operators relative to 'standard' injection coals.

Coal-bed methane (CBM), also referred to as Coal seam gas (CSG), relates to the production of methane from coal beds by drilling wells, hence lowering formation pressure, and triggering methane release. While the potential of this resource is significant, the assessment of the quantity and the producibility of methane from coal seams is highly variable. For this reason the objective of this work is to investigate the assessment of gas content, gas-in-place and coal permeability through petrophysical of analysis and by gaining a better understanding of coal bulk properties,. In this study 17 cored production wells were analysed from the Walloon Sub-group coal seams fairway in the Surat Basin in Queensland Australia, which is today the most ambitious investment in CSG worldwide. A total of 2374 coal beds were investigated to understand how the nature of the different coal lithotypes are reflected in core analysis, wireline logs measurements and DST test results, and how they affect coal quality, and control gas content, fracture development and reservoir permeability. High-resolution studies involving fine scale are required to estimate volumes and CSG formation evaluation turns to the interpretation of standard wireline tools readings in hundreds of coal seam wells. Nevertheless, the heterogeneous thin-bedded nature of coal seams, together with the fact that methane within coal is mainly stored by adsorption, create several difficulties in wireline log petrophysical analysis. Consequently core description is used to validate the combination of the density log with the shallow focused electric and induction resistivity measurements, benefitting the recognition and thickness estimation of thin coal beds and coal laminae rich mudstones. This observation, and a refined coal quality and gas content estimation methodology, are presented and tested against previously published workflows and provide an improved and tested strategy for petrophysical analysis of CSG.

This thesis describes various applications of high field n.m.r. for the elucidation of coal structure, and concentrates on discovering the chemical environments of the heteroatoms in coal i.e. those elements other than carbon and hydrogen. Chapter 2 describes how hydroxyl groups may be converted to trimethyl siloxyl groups, observation of which by 29si n.m.r. allows one to determine the types of hydroxyl functionalities present in the original material. Such derivatization methods are well known. However trimethyl siloxyl groups give 29si resonances that have predictable chemical shifts and so the derivative spectra of complex coal tars and extracts are easy to interpret. Using this technique we have investigated the nature of hydroxyl groups in a rank series of coal tars. This has given us some insight into the way the hydroxyls are affected by coalification. Chapter 3 is a demonstration of the use of n.m.r. as a detector for H.P.L.C. This has two principle novelties over previous work. Firstly it does not involve building a special probe and secondly, the data is presented as a contour plot of intensity vs. retention time and chemical shift. This method has been used to investigate the nature of several tar fractions and complements the derivatization technique of chapter 2. The final chapter shows how the nature of sodium in coal was determined by 23Na MAS-NMR. By using the information contained in the chemical shift and linewidths of raw and dried coal it was concluded that sodium exists bound to the surface of coal pores by oxygen functions such as carboxylates and phenoxides. It does not exist as sodium chloride microcrystals as once thought.

The main objective of this PhD thesis is the study of coal mine dust patterns produced by different types of mining operations and different types of coal. In addition, the potential links between oxidative potential (OP) of coal dust and its geochemistry have been investigated in order to identify indicators of potential concern for human health. To these ends, extensive particle size, chemical, mineralogical and OP analyses were carried out on: i) deposited coal mine dust collected in from different areas in underground and open-pit coal mines; ii) a selection of powdered coal samples from in-seam channel profiles covering a wide and contrasting variety of coal geochemistry patterns. In both cases, the respirable fractions (<4 µm) were extracted and analysed to simulate actual suspended respirable coal dust (PM4). The novelty of these sampling and analytical programmes made it necessary to calibrate and validate new methodologies, and design and implement new protocols, in order to separate the respirable fractions of dust and obtain comprehensive particle size, geochemical and mineralogical characterisations. The results of this thesis are summarised in five scientific articles in high-impact journals. Article #1 introduces the subject and includes a review of major health-relevant coal dust geochemical patterns. Articles #2 to #4 show results from the sampling of deposited coal dust in a number of underground coal mines (China and Europe) and an open-pit coal mine (China), and describe the separation and characterisation of respirable fractions. The samples were collected from different zones of the coal mines in order to encompass the most relevant mining operations being undertaken. In addition, in Article #5, powdered coal seam samples, covering a wide range of geochemical patterns from China, were used to separate and characterise their respective respirable fractions. In Articles #3 to #5 the respirable coal dust samples were selected (according to size and geochemistry) in order to evaluate the relationships among OP markers (ascorbic acid, AA; glutathione, GSH; and dithiothreitol, DTT). This toxicological methodology was applied using cross-correlation and multilinear regression analyses on underground mine dust samples (Article #3), open-pit mine samples (Article #4) and powdered coal samples (Article #5). The approach was repeated including both respirable fractions from deposited coal mine dust and from powdered coal samples (Article #5). Suspended coal dust measurements were reported in Articles #2 to #4 (Europe and China), including online ambient measurement of PM2.5, PM10, BC and UFP (PM <2.5 µm, <10 µm, black carbon, and ultrafine particles, respectively) around several mining open-pit mine (Article #4). The results of this thesis demonstrate that coal dust particle size is a key parameter controlling coal dust resuspension. Coal dust levels, also provide evidence that respirable coal dust levels are markedly higher in the working front areas. Moreover, concentrations and geochemical patterns of coal dust are noticeably influenced by the mining operations carried out in a given mine area. Results for the evaluation of the impact geochemical patterns on the OP demonstrated that OPAA is mostly linked with inorganic species, whereas OPGSH and OPDTT are linked with organic species of coal. The main drivers were found to be Fe, pyrite, sulphate minerals and anatase for OPAA, as well as moisture content, Ca, Mg, Na and Ba, for OPGSH and OPDTT. Furthermore, the correlations of the contents of most of these components in dust or coal with the OPAA, OPGSH and OPDTT increase only in high-rank coal or high coal-rank mine dust (mostly bituminous in this study). Moreover, PM10 measurements reported in this study demonstrate the importance of the effectiveness of dust control measures implemented in underground and open-pit coal mines in order to reduce airborne dust concentrations.
L’objectiu principal d’aquesta tesi doctoral és l’estudi dels patrons de la pols de carbó produïts pels diferents tipus d’operacions mineres i l’estudi dels principals patrons composicionals de diferents tipus de carbó, cobrint un ampli rang geoquímic. A més, la relació entre el potencial oxidatiu (OP) i la geoquímica de la pols de carbó va ser investigada amb la finalitat d’identificar possibles indicadors o traçadors potencials que puguin perjudicar la salut humana. Amb aquesta finalitat, es van dur a terme anàlisis de mida de partícula, químics, mineralògics i d’OP per a: i) la pols de carbó recol·lectat en diferents zones i processos miners per a mines de carbó subterrànies i de cel obert, ii) una selecció de mostres de perfils de capes de carbó moltes, cobrint una àmplia i contrastada varietat de paràmetres geoquímics dels carbons explotats actualment a la Xina. En tots dos casos, les fraccions respirables (<4 µm) van ser separades i analitzades per simular la pols de carbó respirable en suspensió (PM4). La novetat d’aquests protocols de mostreig i anàlisi van requerir tasques de calibratge i validació d’aquestes noves metodologies, i dissenyar i implementar nous mètodes per separar les fraccions respirables de pols i obtenir caracteritzacions completes de mida de partícula, geoquímiques i mineralògiques. L’article #1 és introductori i conté una revisió dels patrons geoquímics de la pols de mineria del carbó més rellevants per la salut humana. De l’article #2 al #4 es mostren resultats per al mostreig de pols de carbó dipositat a nombroses mines de carbó subterrànies (Xina i Europa) i una mina de cel obert (Xina), i descriu la separació i caracterització de fraccions respirables. Les mostres es van recollir a diferents zones de les mines per tal de cobrir les operacions mineres més significatives. També, les mostres de carbó molt de l’article #5, comprenent un ampli rang de patrons geoquímics a la Xina, es van utilitzar per separar i caracteritzar detalladament les fraccions de pols respirable. Als Articles #3 a #5 van ser seleccionades mostres de pols respirable (d’acord amb la seva mida i els patrons geoquímics) per tal d’avaluar les relacions entre els marcadors OP (àcid ascòrbic, AA; glutatió, GSH; i dithiothreitol, DTT) amb els patrons fisicoquímics més rellevants, duent a terme una anàlisi de relació creuada i regressió multilineal per a les mostres de pols de mines subterrànies (Article #3), mostres de pols de la mina de cel obert (Article #4) i mostres de carbó molt (Article #5). Finalment, les anàlisis van ser repetides incloent totes les fraccions respirables de les mostres dipositades de pols de carbó i de les mostres de carbó molt (Article #5). A més de les mesures de pols de mina respirable extretes de pols sedimentada o de carbó molt, es van reportar mesures directes de pols de mina en suspensió dels Articles #2 a #4 (Europa i la Xina), incloent-hi mesures ambientals de PM2.5, PM10, BC i UFP (PM <2.5 µm, <10 µm, carboni negre, i partícules ultrafines, respectivament) al voltant de diverses operacions mineres a la mina de cel obert (Article #4). Els resultats d’aquesta tesi doctoral subratllen la importància de continuar investigant sobre les propietats i nivells de pols a la mineria del carbó en el context de la millora de les condicions laborals dels miners, especialment atès que, probablement, es mantindrà una producció de carbó molt elevada a països com la Xina durant les dècades vinents.
El carbón ha sido un recurso muy valioso en nuestra sociedad durante siglos; sin embargo, sus beneficios como fuente de energía siempre han sido parcialmente contrarrestados por el daño ambiental causado por sus emisiones contaminantes. Aunque se han propuesto muchos acuerdos y políticas para reducir el uso de las energías fósiles, como el Acuerdo de París sobre el cambio climático que trata de reducir las emisiones de gases invernadero, el carbón se sigue consumiendo y produciendo actualmente a gran escala. Además, se pronostica que este escenario permanezca intacto durante las siguientes tres décadas. La exposición a elevados niveles de polvo de minería es considerada un factor de riesgo ocupacional muy importante para los mineros del carbón. Durante el paso del tiempo, las regulaciones mineras, los avances en la ingeniería minera y la mayor consciencia de la seguridad de los trabajadores del carbón ha fomentado mejoras en la protección ocupacional. A pesar de ello, la exposición ocupacional al polvo de carbón durante su minería y manipulación sigue siendo la principal causa de enfermedades pulmonares del polvo del carbón (CMDLD), como la neumoconiosis (CWP), la silicosis y la fibrosis masiva progresiva (PMF). Esto, en parte, probablemente se deba a la mejora en la eficiencia tecnológica de la maquinaria minera usada para trabajar el carbón, resultando en la emisión de partículas más finas y concentraciones más altas de polvo de carbón (al explotarse mayores cantidades de carbón), un efecto que ha estado relacionado con el incremento de CMDLD, afectando incluso a trabajadores más jóvenes. Sin embargo, a pesar de los cambios en los métodos mineros y sus emisiones de polvo, sigue existiendo una notable escasez de estudios paralelos sobre temas relevantes para la salud, relacionándolos con la inhalación de partículas en las minas de carbón modernas. El principal objetivo de esta tesis doctoral es el estudio de los patrones de polvo de carbón producidos por los diferentes tipos de operaciones mineras y el estudio de los principales patrones de distintos tipos de carbón cubriendo un amplio rango geoquímico. Además, se ha investigado la relación entre el potencial oxidativo (OP) y la geoquímica del polvo de carbón con el propósito de identificar posibles indicadores potenciales que puedan perjudicar la salud humana. Con estos fines, se llevaron a cabo análisis de tamaño de partícula, químicos, mineralógicos y de OP para: i) el polvo de carbón recolectado en diferentes zonas y procesos mineros para minas de carbón subterráneas y de cielo abierto, ii) una selección de muestras de perfiles de capas de carbón molidas cubriendo una amplia y contrastada variedad de parámetros geoquímicos de carbones explotados en China. En ambos casos, las fracciones respirables (<4 μm) fueron extraídas y analizadas para simular el polvo de carbón respirable en suspensión (PM4). La novedad de estos protocolos de muestreo y análisis hizo necesario calibrar y validar las nuevas metodologías, y diseñar e implementar nuevos métodos, con el fin de separar las fracciones respirables de polvo y obtener caracterizaciones completas de tamaño de partícula, geoquímicas y mineralógicas. Los resultados de esta tesis doctoral se incluyen en cinco artículos científicos publicados en revistas de alto impacto. El Artículo #1 es introductorio y contiene una revisión de los patrones geoquímicos más relevantes en la salud humana. En los Artículos #2 a #4 se muestran resultados para el muestreo de polvo de carbón depositado en numerosas minas de carbón subterráneas (China y Europa) y una mina de cielo abierto (China), asimismo se describe la separación y caracterización de fracciones respirables. Las muestras fueron recogidas en diferentes zonas de las minas de carbón con el fin de cubrir las operaciones mineras más significativas realizadas en ellas. Además, las muestras de carbón pulverizado del Artículo #5, que comprenden un amplio rango de patrones geoquímicos en China, fueron utilizadas para separar y caracterizar detalladamente sus fracciones respirables. En los Artículos #3 a #5, se seleccionaron muestras de polvo de mina y carbón molido (de acuerdo con su tamaño y los patrones geoquímicos) para evaluar las relaciones entre los marcadores OP (ácido ascórbico, AA; glutatión, GSH; y ditiotreitol, DTT) con los patrones fisicoquímicos más relevantes, llevando a cabo un análisis de relación cruzada y regresión multilineal para las muestras de polvo de minas subterráneas (Artículo #3), muestras de polvo de la mina de cielo abierto (Artículo #4) y muestras de carbón pulverizado (Artículo #5). Por último, se repitieron los análisis incluyendo todas las muestras de las fracciones respirables de las muestras depositadas de polvo de carbón y de las muestras de carbón pulverizado (Artículo #5). Además de las medidas de polvo de carbón respirable extraídas de polvo sedimentado o carbón pulverizado, se llevaron a cabo medidas directas de medidas in-situ y en continuo de polvo de mina en suspensión en los Artículos #2 a #4 (Europa y China), incluyendo medidas en aire ambiente de niveles de PM2.5, PM10, BC y UFP (PM <2.5 μm, <10 μm, carbono negro, y partículas ultrafinas, respectivamente) en torno a varias operaciones mineras en la mina de cielo abierto (Artículo #4). Los resultados de esta tesis doctoral demuestran que el tamaño de partícula del polvo de mina es un parámetro clave para el control de su suspensión. Los resultados también muestran que el tamaño de partícula del polvo depende de los contenidos de humedad y ceniza del mismo, que están negativa y positivamente correlacionados, respectivamente, con el porcentaje de las partículas finas en el polvo sedimentado/depositado. Basándose en la observación de los niveles de polvo de mina de carbón, los resultados evidencian que los niveles de fracción respirable son marcadamente superiores a las áreas del frente de trabajo de la capa de carbón. Desde allí, el polvo decrece considerablemente, aunque las fracciones finas sean fácilmente transportadas a otras partes de la mina, donde también reciben contribuciones de otras fuentes de emisión, como por ejemplo de la minería y manipulación de los estériles, transporte del carbón, sales del drenaje ácido de minas, desgaste de la maquinaria y erosión de galerías gunitadas. Estas contribuciones modifican notablemente el tamaño del polvo de mina y su composición, en comparación con el polvo proveniente del frente de trabajo donde se explota directamente la capa de carbón. Los resultados muestran, pues, que los niveles y patrones geoquímicos del polvo de mina de carbón están notablemente influenciados por las operaciones mineras llevadas a cabo en cada zona específica de la mina. La manipulación y el trabajo del carbón generan un polvo relativamente grueso, con proporciones variables de contenido mineral y matriz orgánica; mientras que la manipulación y el trabajo de los materiales de los estériles producen polvo fino y con alto contenido en ceniza, enriquecido en minerales como arcilla, cuarzo y calcita; los accesos a las galerías están caracterizados por bajos contenidos en polvo, pero con mayor proporción en material respirable, que contienen especies minerales enriquecidas en Ca, y también componentes potencialmente peligrosos (especies sulfatadas ácidas, Fe, As, Sb, entre otros) derivados de las sales de las aguas freáticas infiltradas, que se ven afectadas por el drenaje ácido de minas. El análisis de las fracciones respirables de las muestras de polvo mostró que la mayor parte de las ratios de concentración de las especies y elementos estudiados en ese polvo respirable versus el polvo depositado original fue menor o similar a 1.0. En cambio, ratios para minerales de la arcilla y algunos metales (Se, Mo, Pb, Zn, Sn, As, Cu, Sb, Ni, Co y Cr) alcanzó valores >1.0, indicando su enriquecimiento en su fracción respirable debido a su modo de ocurrencia más fino. Estos enriquecimientos pueden indicar la presencia de polvo proveniente de otras fuentes distintas a las emisiones de polvo de carbón del frente de trabajo, como el drenaje ácido de la mina y emisiones del desgaste de la maquinaria. Ello se ve corroborado por el hecho de que varios de estos elementos también tienen concentraciones más elevadas en PM10, comparados con el polvo respirable depositado. Así pues, aunque los niveles de PM son marcadamente inferiores lejos del frente de trabajo de la capa de carbón, su enriquecimiento en determinados metales y sales evidencian la importancia de monitorizar el polvo de minería en diferentes áreas de la mina, y no tan solo en el frente de trabajo de la capa. Los resultados de OP total (OPTOT) presentados aquí, junto con los de un artículo publicado en 2021 de polvo de mina de carbón en minas turcas, son pioneros en investigar las conexiones de los patrones geoquímicos del polvo de mina y OP. En esta tesis doctoral, los valores de OPTOT obtenidos para el polvo de carbón son marcadamente inferiores a los de otros estudios de PM publicados provenientes de los sistemas de metro urbano, PM en aire ambiente de áreas con altas emisiones de quema de biomasa doméstica y de calles urbanas transitadas. Se dedujo que las especies inorgánicas del polvo de carbón están más relacionadas con OPAA, mientras que las especies orgánicas lo están con OPGSH y OPDTT. Las especies y/o elementos que controlaron el OPAA fueron Fe, pirita, minerales sulfatados y anatasa, mientras que para los indicadores OPGSH y OPDTT fueron los contenidos en humedad (reflejando el contenido en materia orgánica carbonosa), Ca, Mg, Na y Ba. Además, las correlaciones de las concentraciones de la mayor parte de estos componentes en polvo de mina o carbón pulverizado con OPAA, OPGSH y OPDTT incrementaron cuando fueron evaluados sólo los carbones o polvo de carbón de alto rango (bituminosos en este estudio). Los resultados de la evaluación de las características geoquímicas de los carbones explotados en China que controlan el OP del polvo potencialmente generado durante su extracción y manipulación (Artículo #5) demuestran que los contenidos en pirita, ceniza, anatasa, cuarzo, S, Ti y varios metales traza, como Mn, Mo y U, gobiernan la OPAA. Por otra parte, al igual que lo deducido para el polvo de mina, es el contenido en la materia orgánica carbonosa el que gobierna los niveles de OPGSH y OPDTT de las muestras de carbón molido. Estos resultados son similares a los obtenidos en el polvo de mina de carbón respirable, indicando que la extracción de la fracción respirable de las muestras de capas de carbón pulverizado para su posterior análisis geoquímico y de OP se pueden utilizar como indicador del OP del polvo de mina de carbón, atendiendo a las limitaciones indicadas anteriormente, de las posibles fuentes de polvo adicionales a la del frente de trabajo en la capa. Los resultados de los indicadores de OP concuerdan con los de estudios y modelos previos que proporcionan evidencias de asociaciones de determinados elementos y especies en polvo de minería con la generación de especies reactivas del oxígeno (ROS). Especialmente en lo referente a las marcadas correlaciones entre Fe y pirita con OPAA, que demuestran la relevancia de los contenidos de Fe y pirita en polvo de mina y de carbón inhalables con el estrés oxidativo, incluyendo la posibilidad de provocar enfermedades pulmonares y el desarrollo de CWP. Las mediciones de PM10 realizadas en este estudio demuestran la importancia de aplicar medidas efectivas para el control del polvo de minería en las minas de carbón subterráneas y de cielo abierto para reducir su concentración. Especialmente relevantes son los altos niveles de polvo fino medidos en áreas donde los estériles son manipulados sin medidas de control, en la mina de cielo abierto. También, las mediciones in-situ y online de BC y UFP mostraron niveles de exposición moderados, obteniéndose niveles de exposición en cielo abierto comparables a los típicamente registrados en entornos de tráfico urbano intenso. Obviamente este no era el caso para los niveles de PM, siendo estos muy superiores en la mina. La baja dispersión atmosférica en el fondo de la mina de cielo abierto, en comparación con las áreas más elevadas, combinado con la alta maquinaria usada, y el denso tráfico de la zona, proporciona elevados niveles de contaminantes, en especial UFP y PM. Los resultados de esta tesis doctoral subrayan la importancia de seguir investigando sobre las propiedades y niveles de polvo en la minería del carbón en el contexto de la mejora de las condiciones laborales de los mineros; en especial debido a que probablemente se mantenga una producción de carbón muy elevada, en países como China, durante las próximas décadas.
Recursos naturals i medi ambient

Traditional float and sink analyses are undertaken to determine the washability of coal. Float and sink analyses are costly, require toxic heavy organic liquids and the procedure to wash and dry the float and discard fractions is lengthy. QEMSCAN has the ability to characterise particle density based on the mineralogical composition of the particle. The objective of this research is to determine if QEMSCAN is a viable alternative to float and sink analysis. Float and sink analysis typically requires coarse size fractions while QEMSCAN analysis requires samples to be crushed down to 1mm. Any crushing will liberate minerals, which will alter the particle density distribution. Crushing a large particle generates 'puzzle pieces' of the original particle. The smaller 'puzzle pieces' have densities frequently different to the original particle. A mineralogical based particle density prediction model confirms that the float and sink analysis data used in this study is valid. The measured ash contents for the different float and discard fractions were within the expected limits. It is observed that there are a set of controls over the liberation of particles when crushed. Particles in the low float fractions (<1.6g/cm3) predominantly comprise vitrinite rich coal with fine lamellae of kaolinite. The higher float fractions (>1.6-2.0g/cm3) comprise bright and dull coal incorporated into an 'inertodetrinite' texture. Cleats and kaolinite laminae serve as preferential cleavage planes in the lower density fractions, while bright and dull coal serve as preferential breakage planes in the higher float fractions. As a result, these phases are liberated and there is evidence to support that liberation of minerals have controls that can be identified and corrected for. Thus, washability can be determined using QEMSCAN since the significant effect of liberation can be calculated and corrected, for a specific coal type.
Dissertation (MSc)--University of Pretoria, 2015.
Geology
MSc
Unrestricted

The influence of the electrokinetic properties of coal on the adsorption and gasification activities of calcium acetate and potassium carbonate has been studied. It has been found from zeta potential measurements on lignite, subbituminous and bituminous coals that the coal particles are negatively charged in both acidic and basic solutions, although the negative charge density is more pronounced in strongly alkaline media. In general, the extent of calcium or potassium adsorption correlated with the negative zeta potentials. Calcium or potassium adsorption followed the order lignite > subbituminous > bituminous coal. Increased char reactivities were observed with catalysts loaded from basic or neutral solutions compared to catalysts impregnated from acidic solutions. The enhanced activities are attributed to increased contact between the anionic coal surface and the metal ions during catalyst loading. It is suggested that the extent of coal-catalyst interaction during catalyst loading from solution plays an important role in coal char reactivity.

CFD simulations are valuable tools in evaluating and deploying oxy-fuel and other carbon capture technologies either as retrofit technologies or for new construction. However, accurate predictive simulations require physically realistic submodels with low computational requirements. In particular, comprehensive char oxidation and gasification models have been developed that describe multiple reaction and diffusion processes. This work extends a comprehensive char conversion code (the Carbon Conversion Kinetics or CCK model), which treats surface oxidation and gasification reactions as well as processes such as film diffusion, pore diffusion, ash encapsulation, and annealing. In this work, the CCK model was thoroughly investigated with a global sensitivity analysis. The sensitivity analysis highlighted several submodels in the CCK code, which were updated with more realistic physics or otherwise extended to function in oxy-coal conditions. Improved submodels include a greatly extended annealing model, the swelling model, the mode of burning parameter, and the kinetic model, as well as the addition of the Chemical Percolation Devolatilization (CPD) model. The resultant Carbon Conversion Kinetics for oxy-coal combustion (CCK/oxy) model predictions were compared to oxy-coal data, and further compared to parallel data sets obtained at near conventional conditions.

The emission of sulphur oxides during the combustion of coal is one of the causes of an environmental problem known as acid rain. Biodesulphurisation technology applied as a method to remove sulphur before coal combustion was investigated in this work. The desulphurisation abilities of three specific bacterial strains including Rhodococcus erythropolis IGTS8, R. erythropolis X309 and Shewanella putrefaciens strain NCIMB 8768 have been evaluated. R. erythropolis IGTS8 and X309 were found to be able to remove both inorganic and organic sulphur from model compounds and coal samples. Their abilities to remove sulphur from benzothiophene were observed for the first time. A novel desulphurising bacterium, S. putrefaciens was also found to be able to remove inorganic and organic sulphur from coal samples. The bacterium, however, lost its ability to remove organic sulphur from model compounds during the investigation. R. erythropolis IGTS8 presented the greatest desulphurisation efficiency among the three bacterial strains. Nevertheless, the desulphurisation activity of R. erythropolis IGTS8 was too low for an economical coal biodesulphurisation process as it removed only 32.0% of total sulphur in bituminous coal, and 21.1% of total sulphur in anthracite coal. Alternatively, coal biodesulphurisation can be carried out in inexpensive conditions by using the bacteria inherent in the coal itself. The type of coal has an important effect on desulphurisation efficiency since the sulphur reduction in bituminous coal, which is in a lower rank than anthracite, was greater than the sulphur reduction in anthracite coal. This work also developed and evaluated the analytical methods used in the field. A HPLC method was developed to detect the desulphurisation metabolites of model compounds. The techniques for measuring sulphur in coal were improved.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 275-284.
by Myongsook Susan Oh.
Sc.D.

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

Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains viii, 134 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 119-120).

Transportation cost is an important item in total operating cost of an open pit mining operations. In some projects, the transportation cost may reach to 60 % of total operating cost. Turkish Coal Enterprises (TKi) delivers the demanded coal to all cities of Turkey within the context of Prime Ministry Social Solidarity and Aid Fund. The project duration, demanded coal amount whether the coal is needed as packed or unpacked form are determined by local governors. In this study, a model is developed through software, called NAKMAL for the estimation of TKi&rsquo
s coal transportation cost. Transportation cost model is coded using Visual Studio.NET 2005. This model is designed in modular structure and composed of 19 modules. Excavation and transportation in a mine is an important part of the model. Model considers all the highway, railway and transportation by ship alternatives, as well as the packing operation. This model is being used in evaluation of bids by the decision of TKi&rsquo
s board of executive committee.

This study adopts an historical approach to explore the impact of coalmining on the town of Doncaster. It finds that although Doncaster was not a typical mining town nevertheless coal's impact was widespread, and extended beyond direct employment to impact on socio-political factors including the town's external image. Whilst the study explores the impact over the entire one hundred years of mining around Doncaster, the rationale and focus of the study is an assessment of the legacy of the local mining industry, and the extent to which it has inhibited the town's economic competitiveness in what is today called an enterprise economy. In this regard the study contributes to a wider understanding of the nature of change in old industrial regions as well as considering the efficacy of current regional enterprise policy. In particular the study has explored the extent to which path contingency captures the transition from growth to decline in former industrial regions, more adequately than does that of path dependency (Hudson, 2005). The key distinction drawn between the two concepts is human agency which is identified as operating at a range of decision-making levels. Analysis comes through two related case studies which show that the coal industry provided the basis for diversification in to new products and markets offering the possibility to extend the industry's lifecycle and that of towns such as Doncaster which had come to depend on it. It is shown the fact that these opportunities were not taken was due to institutional failure associated with cognitive lock-in. This rather than any specifically industry or place-based factor explains the nature of Doncaster's decline.

Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains x, 93 p. : ill. (some col.), map (part col.). Vita. Includes abstract. Includes bibliographical references (p. 75-78).

Fossil fuels has preserved their importance in gradually increasing production and consumption of both energy and electricity of the world. Asia, especially China and India, has arisen new actors of the sector. Energy and electricity consumption of Turkey has also increased in parallel with her economic development, but due to her limited resources, she has become more and more energy dependent in order to meet her growing demand. Although hard coal is only found around Zonguldak region, with its abundant and widely spread reserves, Turkey ranked world&rsquo
s third place in lignite production in 2008. Having low calorific value together with high ash and moisture content, most of lignites extracted is being consumed in thermic power plants located near those reserves. In the first two chapters of this study, energy in the world and Turkey will be considered seperately, then coal resources in Turkey will be analysed in the next coming chapter. Indirect and direct greenhouse emissions presented to the UNFCCC will be handled in the fifth chapter In the last chapter, first past and present performances of all indigenous coal fired power plants will be analysed, then after projecting their generation and fuel needs, they are evaluated considering with the reserves they are located. Finally, at the end of decomissioning of those power plants, remaining reserves will be re-evaluated and additional new units will be proposed accordingly.

With the export of coal being more lucrative than selling coal to South African power producers, power station operators might consider accepting lower-quality coal. While the impact lower quality coal has on cycle efficiency is understood, the influence it has on equipment reliability and lifetime is often not understood. This study focusses on addressing the question of how different characteristics of coal influences different damage mechanisms of common power station equipment. The results are translated into a reference framework that can be used when coal quality variation is expected. The influence of coal calorific value and ash content has on air-heater element erosion was evaluated. This was accomplished by establishing a correlation between calorific value and ash content of coal from a specific colliery; this was then used to calculate the mass of fly ash and flue gas produced when burning enough coal to satisfy the boiler load. An erosion model was then used along with historical coal quality and air heater erosion history to develop and fit a model for full boiler load. The model was verified against data not used during the development of the model, and a seemingly good prediction was made when compared to the measured result. The calorific value of the coal in the model was varied for a hypothetical situation; this indicated that as calorific value decreases the erosion of air heater elements increases. The influence abrasiveness index has on mill liners was also investigated as part of this study. Historical liner ultrasonic thickness and coal abrasiveness index results were used to fit a mathematical formula. The results indicate that for the ball mills at the power station used in the case study, the abrasiveness index did not have a significant influence on the wear rate of mill liners. The relationship was established to be directly proportional to increased abrasiveness index resulting in an increased wear rate. The final two case studies that form part of this overall study were focussed on boiler temperature variations as a result of variation in coal calorific value and establishing the impact coal “hang-ups” have on the lifetime of a drum reclaimer. The first of these two case studies was completed by creating a mathematical thermo-hydraulic model of a hypothetical boiler and calculating the effect calorific value would have on the boiler temperature distribution. The results were then compared to temperature-related damage mechanisms; the comparison indicated that a variation in calorific value, whether up or down from the designed value would be negative for overall boiler health. The final case study was not completed due to the unavailability of related equipment. A full description of the envisaged study is provided.
Dissertation (MEng)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
MEng
Unrestricted

In modern coal preparation plants, solid-solid and solid-liquid separation processes used to treat fine coal are least efficient and most costly operations. For example, field studies indicate that the froth flotation process, which is normally used to treat minus (-0.2 mm) fine coal, often recovers less than 65 to 70% of the organic matter in this size range. Fine coal separation processes are also inherently less effective in removing pyrite than that of coarse coal separations. Moreover, while fines may represent 10% or less of the total run-of-mine feed, this size fraction often contains one-third or more of the total moisture in the delivered product. In order to address these issues, several multistage coal processing circuits were set up and experimentally tested to demonstrate the potential improvements in fine coal upgrading that may be realistically achievable using an "optimized" fine coal processing flowsheet. On the basis of results obtained from this research, engineering criteria was also developed that may be used to identify optimum circuit configurations for the processing different fine coal streams.
In the current study, several fine coal cleaning alternatives were evaluated in laboratory, bench-scale and pilot-scale test programs. Fine coal processes compared in the first phase of this work included spirals, water-only cyclones, teeter-bed separators and froth flotation. The performance of each technology was compared based on separation efficiencies derived from combustible rejection versus ash rejection plots. The resulting data was used to identify size ranges most appropriate for the various alternative processes. As a follow-up to this effort, a second phase of pilot-scale and in-plant testing was conducted to identify new types of spiral circuit configurations that improve fine coal separations. The experimental data from this effort indicates that a four-stage spiral with second- and fourth-stage middlings recycle offered the best option for improved separation efficiency, clean coal yield and combustible recovery. The newly developed spiral circuitry was capable of increasing cumulative clean coal yield by 1.9 % at the same clean coal ash as compared to that of achieved using existing conventional compound spiral technology. Moreover, the experimental results also proved that slurry repluping after two turns is not effective in improving separation performance of spiral circuits.
The third phase of work conducted in this study focused on the development of methods for improving the partitioning of pyrite within fine coal circuits. The investigation, which included both laboratory and pilot-scale test programs, indicated that density-based separations are generally effective in reducing sulfur due to the large density difference between pyrite and coal. On the other hand, the data also showed that sulfur rejections obtained in froth flotation are often poor due to the natural floatability of pyrite. Unfortunately, engineering analyses showed that pyrite removal from the flotation feed using density separators would be impractical due to the large volumetric flow of slurry that would need to be treated. On the other hand, further analyses indicated that the preferential partitioning of pyrite to the underflow streams of classifying cyclones and fine wire sieves could be exploited to concentrate pyrite into low-volume secondary streams that could be treated in a cost effective manner to remove pyrite prior to flotation. Therefore, on the basis of results obtained from this experimental study, a combined flotation-spiral circuitry was developed for enhanced ash and sulfur rejections from fine coal circuits.
Finally, the fourth phase of work conducted as part of this investigation focused on evaluating a new mechanical, non-thermal dewatering process called Nano Drying Technology (NDT"). Experimental results obtained from bench-scale testing showed that the NDT" system can effectively dewater fine clean coal products from more than 30% surface moisture to single-digit moisture values. Test data obtained using a pilot-scale NDT" plant further validated this capability using a continuous prototype facility. It was also observed that, unlike existing fine coal dewatering processes, the performance of the NDT" system is not constrained by particle size.

Ph. D.

In modern coal preparation plants, solid-solid and solid-liquid separation processes used to treat fine coal are least efficient and most costly operations. For example, field studies indicate that the froth flotation process, which is normally used to treat minus (-0.2 mm) fine coal, often recovers less than 65 to 70% of the organic matter in this size range. Fine coal separation processes are also inherently less effective in removing pyrite than that of coarse coal separations. Moreover, while fines may represent 10% or less of the total run-of-mine feed, this size fraction often contains one-third or more of the total moisture in the delivered product. In order to address these issues, several multistage coal processing circuits were set up and experimentally tested to demonstrate the potential improvements in fine coal upgrading that may be realistically achievable using an "optimized" fine coal processing flowsheet. On the basis of results obtained from this research, engineering criteria was also developed that may be used to identify optimum circuit configurations for the processing different fine coal streams. In the current study, several fine coal cleaning alternatives were evaluated in laboratory, bench-scale and pilot-scale test programs. Fine coal processes compared in the first phase of this work included spirals, water-only cyclones, teeter-bed separators and froth flotation. The performance of each technology was compared based on separation efficiencies derived from combustible rejection versus ash rejection plots. The resulting data was used to identify size ranges most appropriate for the various alternative processes. As a follow-up to this effort, a second phase of pilot-scale and in-plant testing was conducted to identify new types of spiral circuit configurations that improve fine coal separations. The experimental data from this effort indicates that a four-stage spiral with second- and fourth-stage middlings recycle offered the best option for improved separation efficiency, clean coal yield and combustible recovery. The newly developed spiral circuitry was capable of increasing cumulative clean coal yield by 1.9% at the same clean coal ash as compared to that of achieved using existing conventional compound spiral technology. Moreover, the experimental results also proved that slurry repluping after two turns is not effective in improving separation performance of spiral circuits. The third phase of work conducted in this study focused on the development of methods for improving the partitioning of pyrite within fine coal circuits. The investigation, which included both laboratory and pilot-scale test programs, indicated that density-based separations are generally effective in reducing sulfur due to the large density difference between pyrite and coal. On the other hand, the data also showed that sulfur rejections obtained in froth flotation are often poor due to the natural floatability of pyrite. Unfortunately, engineering analyses showed that pyrite removal from the flotation feed using density separators would be impractical due to the large volumetric flow of slurry that would need to be treated. On the other hand, further analyses indicated that the preferential partitioning of pyrite to the underflow streams of classifying cyclones and fine wire sieves could be exploited to concentrate pyrite into low-volume secondary streams that could be treated in a cost effective manner to remove pyrite prior to flotation. Therefore, on the basis of results obtained from this experimental study, a combined flotation-spiral circuitry was developed for enhanced ash and sulfur rejections from fine coal circuits. Finally, the fourth phase of work conducted as part of this investigation focused on evaluating a new mechanical, non-thermal dewatering process called Nano Drying Technology (NDT™). Experimental results obtained from bench-scale testing showed that the NDT™ system can effectively dewater fine clean coal products from more than 30% surface moisture to single-digit moisture values. Test data obtained using a pilot-scale NDT™ plant further validated this capability using a continuous prototype facility. It was also observed that, unlike existing fine coal dewatering processes, the performance of the NDT™ system is not constrained by particle size.
Ph. D.

Thesis (M.S.)--West Virginia University, 2008.
Title from document title page. Document formatted into pages; contains x, 164 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 119-121).

There are three related studies within this thesis that examine the relationships between the properties of coals and the characteristics of the chars produced during rapid pyrolysis in a laboratory based Entrained Flow Reactor (EFR) which simulates the rapid rates of heating (104 to 105 °C s-1 ) typical of pulverised fuel boilers. The first study, using a suite of nine coals, investigates the influence of coal rank upon the generation of specific types of char, their respective physical and structural characteristics and their relative combustabilities. The second study, using a suite of twenty-two coals, examines various coal characterisation techniques and the correlations between those techniques and the associated char, and specifically investigates petrographic techniques as a means of characterising coal feedstock. The third study, using freshly mined coals, investigates the effects of oxidation (100°C, air) and weathering (ambient) upon standard analytical techniques and relates such changes to the physical, structural and combustion characteristics of the associated char. There is a common relationship between the elemental oxygen content of the parent coal and the generation of specific types of char for both vitrinite rich coals of differing coal rank and for the oxidised or weathered coals. There is also an inverse relationship (R 2 = 0.97) between the elemental oxygen content of a vitrinite rich coal and the proportion of cenospheres generated by pyrolysis at 1000°C using the EFR. Furthermore, the enhancement of char combustion at 1000°C (in an EFR) is related to the physical and structural characteristics of the char, i.e. the presence or absence of porosity (visible using SEM and TEM), the CO2 surface area and optical texture. A relationship exists (R2 = 0.83) between the morphology of a char (1000°C / N2) and the petrographic composition of the parent coal. The new term microlithotype, is an amalgamation of various vitrinite rich microlithotype classes that simplifies the nomenclature. A combination of calorific value, microlithotype, and coal rank (vitrinite reflectance) illustrates the influence of petrographic composition upon calorific value and also suggests a 'Province' dependency amongst the Cretaceous/Tertiary and Carboniferous coals studied. The coal properties calorific value, microlithotype, and coal rank can be related (R 2 = 0.91) to the proportion of porous chars for the Cretaceous/Tertiary suite of coals, illustrating the use of multivariate analyses when characterising coal feedstock. The effects of oxidation and weathering upon vitrinite fluorescence is also reported. The oxidation of coal at 100°C produces rims of quenched fluorescence which are not apparent within the weathered coals. Furthermore, the intensity of fluorescence at 650 nm (1650) decreases due to progressive oxidation or weathering, but decreases at a rate that is dependent upon the severity (temperature) of the conditions employed. The proposed oxidation quotient (0/Q = I65W%Romax) is a sensitive indicator of the oxidative conditions up to 100°C.

The study describes the experiences of a small sample of men from Westoe Colliery in South Shields within a comprehensive conceptual framework, that is rather than taking the closure as its starting point this study attempts to understand the importance and relevance of redundancy in terms of the men's life experience. For this reason the men's reasons for entering mining and their subsequent attachment to work are considered as is the increasing dissatisfaction with work experienced following the closure announcement. This study seeks to add to our understanding of the process of redundancy and the way in which redundancy was achieved with relative ease. As Wood and Dey (1983) have noted reactions to redundancy are, of course, affected by the current state of the labour market but they are also affected by other factors. The role of redundancy payments is examined and it is found that such payments have an extremely important role in easing the process of redundancy, however they cannot be considered in isolation from other factors that served to constrain the workers' choices. Redundancy is a far more complex process than many studies have suggested and cannot be understood without considering how previous experiences. influence workers' perceptions of events and their reaction to them. The labour market experiences of the redundant men and the role of British Coal Enterprise are also examined and this study, in common with others, questions BCE's claims of success in 'outplacing' redundant miners. The men's experiences are considered in the context of Government and employers' attempts to increase flexibility. It is found that redundant miners, like an increasing proportion of Britain's workforce, are experiencing increasing insecurity both in and out of employment.

The high temperature interactions of alkali metal compounds with solids present in coal conversion processes are investigated. A temperature and concentration programmed reaction method is used to investigate the mechanism by which organically bound alkali is released from carbonaceous substrates. Vaporization of the alkali is preceded by reduction of oxygen-bearing groups during which CO is generated. A residual amount of alkali remains after complete reduction. This residual level is greater for potassium, indicating that potassium has stronger interactions with graphitic substrates than sodium. Other mineral substrates were exposed to high temperature alkali chloride vapors under both nitrogen and simulated flue gas atmospheres to investigate their potential application as sorbents for the removal of alkali from coal conversion flue gases. The compounds containing alumina and silica are found to readily adsorb alkali vapors and the minerals kaolinite, bauxite and emathlite are identified as promising alkali sorbents. The fundamentals of alkali adsorption on kaolinite, bauxite and emathlite are compared and analyzed both experimentally and through theoretical modeling. The experiments were performed in a microgravimetric reactor system; the sorbents were characterized before and after alkali adsorption using scanning Auger microscopy, X-ray diffraction analysis, mercury porosimetry and atomic emission spectrophotometry. The results show that the process is not a simple physical condensation, but a complex combination of several diffusion steps and reactions. There are some common features among these sorbents in their interactions with alkali vapors: In all cases the process is diffusion influenced, the rate of adsorption decreases with time and there is a final saturation limit. However, there are differences in reaction mechanisms leading to potentially different applications for each sorbent. Bauxite and kaolinite react with NaCl and water vapor to form nephelite and carnegieite and release HCl to the gas phase. However, emathlite reacts to form albite and HCl vapor. Albite has a melting point significantly lower than nephelite and carnegieite; therefore, emathlite is more suitable for lower temperature sorption systems downstream of the combustors/gasifiers, while kaolinite and bauxite are suitable as in-situ additives.

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.

The geochemistry and mineralogy of coal from the Absaloka, Rosebud, and Decker mines located in the Powder River Basin in Montana have been characterized to determine the bulk composition of inorganic constituents in the coal; mineralogy of the coal, including the identity, morphology, composition and distribution of minerals present; occurrence and distribution of potentially hazardous trace elements; and chemical state of selected elements (N, O, S). These data were acquired using instrumental neutron activation analysis (INAA), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and time of flight mass spectrometry (ToF-SIMS). In aggregate, these analytical techniques provide complementary information and also allow for cross-technique comparison of results. Overall the Montana coals contain mineral assemblages that are typical of coals described from across the United States and the world. Comparing Montana Powder River basin coal versus the rest of the United States coals, Montana Power River has, overall, a remarkably lower abundance of potentially hazardous elements. XRD analysis revealed kaolinite in all samples, variably present are quartz, illite, calcite, dolomite, gypsum, and pyrite. SEM/EDS imaging and analysis confirmed the occurrence of these mineral phases and the dominance of kaolinite in ash layers. Pyrite is the primary sulfide mineral that occurs in a variety of crystal forms that could affect its solubility, and therefore, potential for acid release. Pyrite occurs as a pure compound with no As nor other potentially hazardous element as part of a solid solution. However XPS analysis of sulfide rich areas reveal a concentration of Se and Co suggesting these elements are sorbed onto the pyrite surfaces. This study provided a reconnaissance overview of the geochemistry and mineralogy of these Montana coal mines. Future work could include a more detailed chemical stratigraphy of the coal-producing layers to better characterize the distribution of minerals and elemental components in the coal, and to determine the processes responsible for their occurrence and distribution. The results of this study are applicable to the future development of clean coal technologies and to address the potential environmental and health impacts of coal combustion.

Currently, coal combustion plays an important role in meeting the energy needs of the United States. It is expected that the effective utilization of coal will be crucial for attaining energy independence for the nation in the next 25 to 30 years, if not longer. The United States burns about 20% of the world's annual coal production, second only to China. Strikingly, there are 200-300 more years of burn at our current rate of consumption, considering our massive coal reserves. Almost half of our electricity comes from coal power. Although coal is a fossil fuel that will become more and more depleted, it will be the principal fuel for utilities in the US for decades to come. Therefore, there is a need to design new strategies to clean coal. Mercury can be found in fly ash, bottom ash, and flue gas desulfurization (FGD) material. The Hg is transferred to these coal combustion products (CCPs) from its associated parent coal. These CCPs absorb a significant amount of the Hg released during the combustion process. With the EPA's recent emphasis on controlling the Hg emission by coal-burning electric utilities, the disposal and utilization of CCPs are under an environmental microscope. As EPA regulations become more stringent, Hg concentration in CCPs is expected to increase further; i.e., more Hg will be captured in the scrubber materials. The higher Hg concentrations will have serious consequences for the management of CCPs. Systematic measurements on Hg concentrations in the feed coal and the CCPs produced from two different power plants burning Illinois coal were carried out. Not only were there substantial variations in the total Hg concentration in the parent coal from week to week from a single mine, but there were also significant variations in the weekly Hg content of the CCPs. Surprisingly, there was no linear dependence between Hg content of coal and its CCPs. No correlation was observed between Hg content of fly ash and its loss-on-ignition (LOI) values. In order to control and further understand the fate of Hg in FGD scrubber material, the following was systematically examined: (a) whether there is a strong correlation between the parent coal and the Hg captured in FGD scrubber materials, (b) the thermal behavior of Hg in parent coal, FGD gypsum, and sulfite-rich FGD material, (c) whether there is a potential of Hg re-emission during gypsum-to-hemihydrate-to-gypsum transition, and (d) how Hg behaves in sulfite-rich scrubber material at higher temperatures and pressures. Ultimately, no direct correlation between the total Hg concentration of the parent coal and its associated FGD scrubber materials was found. Mercury desorbed from FGD gypsum at relatively low temperatures (90C < T < 250C), compared to the sulfite-rich scrubber materials which released Hg continuously at ambient pressures up to 600C. However, it was found that mildly-elevated pressures immobilized Hg, even at temperatures as high as 250C. Cleaning and dewatering coal has been a major challenge. Deeper pre-combustion cleaning of ashes and clays from coals can help utilize more of Illinois coal. Efforts have been underway for decades to reduce emissions from flue gas and toxic metal reduction. Now with carbon emissions under scrutiny, the effort to maximize coal's value is more important than ever before. In most coal preparation processes, significant amounts of fines and ultrafines are generated. Because these particles are difficult to dewater, they are often discarded in waste ponds. This translates into a major economic loss for the coal industry, not only because of the fuel value lost but also the substantial economic resources required to manage coal waste ponds in an environmentally-sound manner. A new approach developed using a high intensity sonication process in recovering, cleaning, and dewatering fine/ultrafine coal particles from the waste ponds, while concurrently reducing the Hg concentration in the fine and ultrafine particles was successful. Combining sonication with vegetable oil agglomeration significantly reduced the moisture, ash, and Hg content of the cleaned, recovered coal. Differential scanning calorimetry (DSC) measurements on the recovered coal were used to understand the interaction between the coal particles, water, and oil. The results suggested that vegetable oil was effective in displacing water from the coal-water interface, with the enthalpy of the water-vapor transition of oil-agglomerated coal particles decreasing on sonication of the particles. In fact, combining sonication treatment with oil agglomeration reduced the moisture content of run-of-mine (ROM) coal and waste coal, to 6 wt% and 12 wt% respectively, and increased their loss-on-ignition (LOI) content to 91 wt% and 76 wt%, respectively. Massive quantities of synthetic gypsum are produced when the flue gases from coal burning power plants are wet scrubbed with limestone. The sulfate-rich FGD scrubber material is largely construction-quality gypsum. Because of the large production of FGD gypsum every year, the economic and environmental impetus dictates that strategies be developed to effectively utilize FGD gypsum rather than just landfill it. Beneficial uses have been found in wallboard construction and agriculture. An important aspect of this research was to evaluate whether there was potential of Hg re-emission from scrubber materials during their utilization phase. Mercury emission occurs not only with elevated temperatures but with increased time. While external pressure retards these emissions, they are not the only concern associated with CCPs. The more global, urgent problems of greenhouse gases must be resolved. The dimension of the greenhouse gases problem is daunting; according to the Energy Information Agency, nearly 6 billion metric tons of CO2 were produced in the USA in 2007, with coal-burning power plants contributing about 2 billion metric tons. The success of large-size sequestration of CO2 in coal would hinge on a thorough understanding of coal-CO2 interactions and how these interactions control the mechanical behavior of coal. Moreover, these interactions could play a crucial role in evaluating any potential risks associated with sequestering CO2 in deep, unmineable coal seams. To evaluate the risk under non-equilibrium conditions, dynamic mechanical properties of pressurized Illinois coals were measured. The results suggest that Illinois bituminous coal in its unperturbed state, i.e., when not pressurized with CO2, showed large variations in its mechanical properties. The Young's modulus varied from 0.7 GPa to 3.4 GPa even though samples were extracted from a single chunk. No glass transition was observed for any Illinois bituminous coal under ambient conditions. Upon pressurizing the Illinois bituminous coals with CO2, the DMA results showed a transition at temperatures as low as ambient. This could be a potential risk for the structural integrity of a mine if any man-made or seismic activity were present.

>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.

Coal use in electricity generation has attracted much attention recently mainly due to the sector been identified as the main source of sulphur dioxide (SO2) emissions globally. The combustion of coal releases sulphur dioxide emissions into the atmosphere that create air pollution and cause harmful effects on the ecosystem. In the current study, biodesulphurization of Waterberg steam coal was investigated using a bacterial consortium isolated from coal. Coal samples were obtained from the coal feed into the power plant mills, by auto sampling equipment. Coal samples with various particle size fraction of +4.60 mm, −4.60 + 2.30 mm, −2.30 + 1.00 mm and −0.85 mm were used in the biodesulphurization experiments. The characteristic properties of the coal samples were analysed by means of a number of techniques, including Leco S-628 Elemental analyser, UV Spectrophotometry, bomb calorimeter and X-Ray Fluorescence. The contribution of this study to the country's minimum emissions requirements and compliance could be outlined as follows: Coal was classified as medium sulphur coal when the sulphur content was detected in the range 1.15 – 1.49 wt.%. Four forms of sulphur - pyrite, mineral/sulphide sulphur, inorganic sulphates and organic sulphur were present in Waterberg coal with pyritic sulphur (≥ 0.51 wt.%) and organic sulphur (≥ 0.49 wt.%) accounting for the bulk of the total sulphur in coal.
Thesis (PhD)--University of Pretoria, 2020.
UP Postgraduate Bursary
Chemical Engineering
PhD (Chemical Engineering)
Unrestricted

Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains xvi, 135 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 107-109).

In recent years, the consequences of global warming have increased the discussion about the climate impact caused by humans and the fossil emissions. Sweden has decided to reduce the negative climate impact with a zero vision for the fossil carbon dioxide emissions in year 2045. In order to achieve this, great efforts and changes are needed both in the inhabitants' way of living but primarily in the base industry. The major cause is the use of fossil coal, which generates fossil carbon dioxide in the steel industry in particular. The fossil coal is added to the blast furnace in the steel process in forms of coke and coal, which reduces the iron and emits heat. The quality of the coke is important as it functions reducing agent, provides a mechanical support to the bed and enables the gas flow up through the blast furnace and enables dissolution of carbon in hot metal. Also, coke supplies energy from exothermic reactions between carbon and carbon dioxide that takes part in the blast furnace and the energy are further used for the heating and melting of the cold iron pellets. Due to these factors, the blast furnace process is dependent on coke for its function, which means that the entire process must be replaced if the steel production should work without fossil coal. However, there are many studies that have been done on how to replace some of the fossil coal with bio-coal, which is produced from biomass. If some of the fossil coal could be replaced by some bio-coal, this would mean that fossil carbon dioxide emissions would decrease and lead to a reduced climate impact. The process would still generate carbon dioxide, but on the other hand, a cycle would be formed because when biomass is grown, carbon dioxide is taken up, e.g. by the trees grown for this purpose. However, bio-coal does not have the same properties as fossil coal, which in turn affects the quality of the coke. Bio-coke is more reactive and more porous than fossil coke. In order to be able to replace fossil coke with bio-coke, it is likely necessary to pre-treat the biocoal before it replaces part of the fossil coal in the coke production. Bio-coal contains ash that acts as an internal catalyst. One theory is that if it is possible to produce a bio-coal with ash-free carbon structure, it can be used in the production of coke without having such a great effect on the coke quality. In this project, the ash's impact on the properties of bio-coal in coke was studied. Previous studies have shown that leaching is an effective method for removing ash from bio-coal. It can be leached in three different ways, either with water, weak acid or acid. However, it has been found that acid leaching has a certain impact on the carbon structure itself. For this reason, two types of bio-coal, torrefied Grot (forest residue) and torrefied sawdust were selected, which were leached both with water but also with weak acid in order to achieve an ash-reduced carbon structure. The acid selected was acetic acid, as it has been tested for similar purposes in previous studies. The leaching efficiency was evaluated by analysing the leachate with ICP-OES after leaching. According to the result, a significant part of the ash had been leached out, but the leaching with weak acid was much more effective than water leaching. To ensure that the carbon structure was not altered, light-optical microscopy was made which showed that the structure was intact. However, it was not possible to determine whether the pore sizes were changed after leaching and it is therefore relevant to investigate this further. Moreover, the leached II bio-coal replaced 5% of the fossil coal in the coal mixture for coke making. In addition to this, coke was also made with only the ash from the two bio-coals to see what effect the ash has on the coke quality. The result that was obtained from the TGA showed that the ash had a low impact on the reactivity of the coke. However, the coal structure of the coke had a great impact on the reactivity behaviour. Keywords: Bio-coke, bio-coal, leaching, ash, coke quality, carbon structures, torrefied sawdust