Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 158-163). Also available via the Internet.

Oxy-combustion is a process which removes nitrogen from air prior to combustion in order to produce a high concentration of CO2 in the exhaust. This enables CO2 liquefaction, transport, and storage to greatly reduce CO2 emissions to the atmosphere. Atmospheric oxy-coal combustion has been successfully demonstrated at industrial scales and could be retrofit in existing coal boilers, but thermodynamic efficiencies are low and therefore uneconomical. Pressurized oxy-coal combustion has the potential for higher efficiency and lower cost but requires new technologies related to the coal feed system, the burner, and ash management. This project describes work needed to complete the dry feed pressurized oxy-coal combustor (POC) at BYU. The POC required the software control system (OPTO22) to be completed, a reactor shakedown, and testing of a previously designed burner by recording reactor thermocouple, exhaust concentration, and radiometer measurements. The following has been successfully demonstrated: 1) reactor heat-up with natural gas 2) coal combustion within temperature limits of the reactor 3) slagging that allows ash management.

A injeção de carvão pulverizado (pulverized coal injection - PCI) é uma técnica largamente utilizada nos altos-fornos pelas siderúrgicas brasileiras, seguindo uma tendência mundial, que busca reduzir o consumo específico de coque por tonelada de gusa e, em consequência, do custo do ferro gusa produzido. A combustão do carvão pulverizado ocorre sob pressões médias (de até 4 atm), temperaturas de chama elevadas (em torno de 2 000 °C), altas taxas de aquecimento (104 a 105 °C/s), tempo de residência muito curtos (inferiores a 40 ms), e é seguida pela gaseificação na presença de CO2. Como não existem métodos padronizados para a avaliação das características de combustão dos carvões para sua utilização em PCI, utilizam-se geralmente equipamentos de injeção de carvão em escalas laboratorial e de bancada, além plantas-piloto com este propósito. O objetivo principal deste trabalho é apresentar as etapas do desenvolvimento de um equipamento em escala de bancada realizado no Laboratório de Siderurgia da Escola de Engenharia da UFRGS (LASID-UFRGS), desde o projeto conceitual até a fase pré-operacional, e os resultados iniciais obtidos, para estudar as características de combustão dos carvões em condições bastante similares às que ocorrem nos altos-fornos. Os testes iniciais incluem a avaliação da combustão de um carvão brasileiro objetivando seu uso potencial em PCI, em substituição parcial de carvões importados para este fim. Optou-se por um projeto moderno, altamente automatizado, que inclui aquisição rápida de dados, com escala e conceito operacional adequados para estudos acadêmicos, de configuração vertical e que possibilitasse a operação no modo de injeção de uma amostra de carvão em pulso único, bem como uma adequação futura ao modo de injeção contínua de carvão. Algumas características relevantes do equipamento são a medição e aquisição ultrarrápida de dados termodinâmicos de pressão e temperatura em diversos pontos do sistema, permitindo o registro dos fenômenos transientes que ocorrem durante a combustão, a possibilidade de programação e controle de tempos, pressões e temperaturas para testes de combustão e de pirólise através de rotinas especialmente desenvolvidas para isto, bem como a coleta representativa dos produtos sólidos e gasosos resultantes da combustão para posterior análise. É ainda possível a filmagem da xvi combustão em modo ultrarrápido, permitindo correlacionar as imagens aos dados termodinâmicos registrados durante a combustão ao longo de um segundo, em intervalos de poucos milissegundos. Os resultados iniciais obtidos na fase pré-operacional demonstram o bom funcionamento do sistema, permitindo distinguir claramente a influência da variação de parâmetros operacionais como tipo de carvão, massa e de amostra injetada, pressão e temperatura de operação e composição dos gases oxidantes. / Pulverized coal injection (PCI) is a technique used in blast furnaces (BFs) by Brazilian steel industry, following a worldwide trend, to reduce coke consumption by ton of hot metal produced, and therefore reducing the overall cost. Burning of pulverized coal injected into tuyeres of BFs takes place under medium pressure (up to 4 atm), high flame temperatures (around 2 000 °C), very fast heating rates (104–105 °C/s) and very short residence times, less than 40 ms, followed by gasification in presence of CO2. Since there are no standard tests for evaluation of coal combustibility at PCI conditions, lab and bench scale coal injection rigs and pilot plants are usually employed for this purpose. This work shows the development steps of a bench-scale rig, built at the Iron and Steelmaking Laboratory of the School of Engineering - Universidade Federal do Rio Grande do Sul (LASID-UFRGS), from the conceptual design to the pre-operational step, as well as the initial results. This equipment permits to study the combustion characteristics of coals in conditions very close to those occurring in blast furnaces. Initial tests include the combustion evaluation of a Brazilian coal, aiming its potential usage for PCI, in partial substitution of imported coals for this purpose. The rig has a modern design and is highly automated. Its scale and operational concept is fitted for academic studies. It has a vertical configuration, to be operated with injection of a coal sample in a single pulse mode and is capable to be adjusted afterwards to continuous coal injection mode. Some relevant characteristics of the injection rig are: (1) the very fast measurement and acquisition of thermodynamic data of pressure and temperature in several points of the system, allowing the capture of transient phenomena occurring along the combustion process; (2) the possibility of programming and controlling time intervals, pressures and temperatures to perform combustion and pyrolysis tests, employing specially developed routines; and (3) the representative sample collection of solid and gaseous combustion products to be further analyzed. It is also possible to capture images of the combustion by a high-speed camera, allowing correlate the images, acquired during a time interval of one second, with the thermodynamic data collected in intervals of few milliseconds. xviii The good performance of the equipment was shown by the initial results obtained at the pre-operational phase. The experimental data clearly depicted the effect of operational parameters like coal type, injected sample mass, operational pressure and temperature, and oxidizing gas composition.

Die Arbeit befasst sich mit der Flamelet Modellierung für die Verbrennung von Kohlenstaub. Dabei liegt der Fokus sowohl auf der detaillierten Betrachtung der Gasphasenchemie als auch auf der Interaktion der Kohle mit der Gasphase. Ziel der Arbeit ist die Entwicklung einer Methode für die Simulation großtechnischer Kohlestaubfeuerungen. Die energetische Umsetzung von Kohle läuft in drei wesentlichen Schritten ab: Verdampfung der Feuchtigkeit, Ausgasung der Kohle (Pyrolyse) und schließlich der Koksabbrand. Da die Struktur der Kohle als fossiler Brennstoff hoch komplex ist, existieren viele prädiktive, rechenaufwändige Modelle zur Beschreibung dieser Prozesse [1–4]. Diese Modelle können nicht direkt in numerischen Strömungssimulationen genutzt werden, dienen aber zur Kalibrierung einfacherer kinetischer Modelle. Diese in der Arbeit angewendete Prozedur wird in [5] beschrieben. Zur detaillierten Beschreibung des Abbaus der entstehenden höheren Kohlenwasserstoffe werden in der Simulation große Reaktionsmechanismen benötigt. Die Benutzung solcher Mechanismen ist mit großen Rechenzeiten verbunden und daher bleibt deren Anwendbarkeit auf einfache Anwendungsfälle beschränkt. Der Vorteil der Flamelet Modellierung besteht darin, dass unter bestimmten Voraussetzungen der komplette thermo-chemische Zustand, bestehend aus Temperatur, Druck und Zusammensetzung, mit nur wenigen charakterisierenden Kontrollvariablen abgebildet werden kann. Durch Vorgabe und Variation der Kontrollvariablen können diese Zustände mittels kanonischer Flammenkonfigurationen vorberechnet und in sogenannten Flamelettabellen abgespeichert werden. Für das klassische Flamelet / Fortschrittsvariablen Modell [6] wird der thermo-chemische Zustand über Mischungsbruch und Fortschrittsvariablen parametriert, dabei bestimmt der Mischungsbruch den Anteil an Brenn- stoff im Gemisch und die Fortschrittsvariable den Fortschritt der chemischen Reaktion. Die Kontrollvariablen werden in der numerischen Simulation transportiert, an Stelle der Energie- und Speziesgleichungen. Dies stellt für große Mechanismen eine dramatische Reduktion der zu lösenden Gleichungen dar. Der thermo-chemische Zustand ergibt sich per Look-up aus den Flamelettabellen. Im Zuge der Verbrennung trockener Kohle werden zwei Brennstoffe durch Pyrolyse und Koksabbrand freigesetzt. Für die Flamelet Modellierung bedeutet dies entsprechend je einen Mischungsbruch für Pyrolysegas und Produkte aus dem Koksabbrand. Neben der Fortschrittsvariablen wird ebenfalls die Enthalpie der Gasphase als Kontrollvariable benötigt aufgrund des intensiven Wärmeaustauschs zwischen Kohle und Gasphase. In der Arbeit erfolgt die Vorstellung der benötigten Transportgleichungen sowie die Beschreibung verschiedener Methoden zur Integration nicht-adiabater Zustände in Flamelettabellen. Dabei unterscheiden sich die vorgestellten Tabellierungstrategien hauptsächlich in der betrachteten Verbrennungsart. IV Erfolgt die Mischung von Brennstoff und Oxidationsmittel erst in der untersuchten Flammenkonfiguration, spricht man von Diffusionsflammenstrukturen; sind beide schon gemischt, so entstehen Vormischflammenstrukturen. Die Detektion solcher Strukturen erfolgt in der Arbeit anhand einer Flammenstrukturanalyse mittels Flammenmarker. Die prinzipielle Übertragbarkeit des Flamelet / Fortschrittsvariablen Modells auf turbulente Kohlestaubfeuerung wurde von Watanabe [7] gezeigt, jedoch ist die Bewertung der eingesetzten Flamelet Modellierung in Grobstruktursimulationen nicht ohne weiteres möglich. Deshalb werden zur Verifizierung der entwickelten Tabellierungstrategie in der Arbeit einfache Flammenkonfigurationen betrachtet, die es erlauben, direkte Chemielösungen mit den Lösungen der tabellierten Chemie zu vergleichen. Für den entsprechenden Vergleich erfolgt die Vorstellung zweier Analysen. Bei der a priori Analyse wird der thermo-chemische Zustand der detaillierten Lösung mit dem tabellierten Zustand verglichen. Für den Look-up werden dabei die Kontrollvariablen der direkten Chemiesimulation benutzt. Die a posteriori Analyse ist der Vergleich einer voll gekoppelten Rechnung unter Benutzung der Tabellierungstrategie mit der zugehörigen detaillierten Rechnung. Die erste untersuchte Konfiguration stellt eine Gegenstromanordnung mit vorgewärmter Luft und Kohlebeladung dar. Die Hauptergebnisse dieser rein numerischen Studie wurden bereits veröffentlicht [8] und es konnte die erfolgreiche Applikation der vorgestellten Tabellierungstrategie in dieser Anordnung für Tabellen basierend auf Diffusionflammenstrukturen gezeigt werden. Für die Validierung der detaillierten Rechnungen erfolgt die Nutzung experimenteller Daten [9, 10] für magere Methan-Sauerstoff-Stickstoff Mischungen in Staupunktströmungen. Es zeigt sich, dass diese Konfigurationen stark von den vorgemischten Gasflammen dominiert werden und somit Tabellen basierend auf Vormischflammenstrukturen einzusetzen sind. Die entwickelte Tabellierungsmethode ist in der Lage, auch diese Flammenstrukturen abzubilden. Abschließend wird numerisch eine Parametervariation hinsichtlich Einlassgeschwindigkeit und Kohlebeladung vorgestellt, um die Robustheit und breite Anwendbarkeit der entwickelten Tabellierungstrategie aufzuzeigen. Zusammenfassend konnte mittels Flammenstrukturanalyse für jede vorgestellte Konfiguration der zu verwendende Typ der Tabelle bestimmt werden. In den untersuchten Konfigurationen führte deren Anwendung zu einer guten Übereinstimmung mit den detaillierten Rechnungen. Damit legt diese Arbeit den Grundstein für weiterführende Betrachtung zur Simulation großtechnischer Kohlestaubfeuerungen.

Oxy-combustion is a developing technology that enables carbon dioxide (CO2) capture. Flame temperature and emissivity data were taken on a 150 kWth, pulverized-coal, burner flow reactor (BFR) that has been modified to run oxy-combustion with pure CO2 as simulated recycled flue gas. Data were taken at 78 conditions in which three parameters were varied, namely: the swirl angle of the fuel stream, the location of the oxidizer as it exited the burner, and the flow rate of diluent (pure CO2) added to the outer, secondary stream. At each condition, digital color images were obtained using a calibrated RGB camera. The images were used to determine lift-off length, temperature, and emissivity. The mathematical theory of two-color pyrometry and the calibration process used to measure the camera sensitivity is presented. The two most commonly used emissivity models in two-color pyrometry, the Hottel and Broughton and gray models, were investigated to determine which was the most appropriate for use in an oxy-coal flame. A significant difference of 7% in the temperature and 24% in the emissivity results were found when processing an image with the Hottel and Broughton and gray emissivity models. The Hottel and Broughton model was selected for processing, because the Hottel and Broughton model is more appropriate for soot which appeared to dominate flame emissions. Using the two-color data, several trends were documented. Flame temperature was seen to decrease with increasing CO2 flow rate. Within a given flame along the axial direction, temperature was seen to correlate with emissivity. As emissivity increased, flame temperature was seen to decrease. Many flames were lifted from the burner exit. Lift-off length was decreased and the flames became more attached by: 1) Increasing the amount of swirl given to the fuel stream, 2) Adding O2 to the center primary tube or 3) Decreasing the flow of secondary CO2. At higher center oxygen flow rates (above 8.5 kg/hr), the O2 jet velocity was large causing increased entrainment and mixing which degraded burner performance.

The need for electric power across the globe is ever increasing, as is the need to produce electricity in a sustainable method that does not emit CO2 into the atmosphere. A proposed technology for efficiently capturing CO2 while producing electricity is pressurized oxy-combustion (POC). The objective of this work is to design, build, and demonstrate a burner for a 20 atmosphere oxy-coal combustor. Additionally, working engineering drawings for the main pressure vessel and floor plan drawings for the main pressure vessel, exhaust, and fuel feed systems were produced. The POC reactor enables the development of three key POC technologies: a coal dry-feed system, a high pressure burner, and an ash management system. This work focuses on the design of a traditional diffusion flame burner and the design of the main reactor. The burner was designed with the intent to elongate the flame and spread heat flux from the reacting fuel over a longer distance to enable low CO2 recycle rates. This was done by matching the velocities of the fuel and oxidizer in the burner to minimize shear between incoming jets in order to delay the mixing of the coal and oxygen for as long as possible. A spreadsheet model was used to calculate the jet velocities and sizes of holes needed in the burner, comprehensive combustion modeling was outsourced to Reaction Engineering International (REI) to predict the performance of burner designs. Using the guidance of the modeling results, a burner design was selected and assembled. The burner consists of a center tube where the primary fuel will flow, two concentric secondary tubes making an inner and an outer annulus, and eight tertiary lances. The burner and reactor are ready to be tested once issues involving the control system are resolved. Measurements that will be taken once testing begins include: axial gas and wall temperature, radiative heat flux, outlet gas temperature, and ash composition.

abstract: Carbon capture and sequestration (CCS) is one of the important mitigation options for climate change. Numerous technologies to capture carbon dioxide (CO2) are in development but currently, capture using amines is the predominant technology. When the flue gas reacts with amines (Monoethanaloamine) the CO2 is absorbed into the solution and forms an intermediate product which then releases CO2 at higher temperature. The high temperature necessary to strip CO2 is provided by steam extracted from the powerplant thus reducing the net output of the powerplant by 25% to 35%. The reduction in electricity output for the same input of coal increases the emissions factor of Nitrogen Oxides, Mercury, Particulate matter, Ammonia, Volatile organic compounds for the same unit of electricity produced. The thesis questions if this tradeoff between CO2 and other emissions is beneficial or not. Three different methodologies, Life Cycle Assessment, Valuation models and cost benefit analysis are used to identify if there is a net benefit to the society on implementation of CCS to a Pulverized coal powerplant. These methodologies include the benefits due to reduction of CO2 and the disbenefits due to the increase of other emissions. The life cycle assessment using ecoindicator'99 methodology shows the CCS is not beneficial under Hierarchical and Egalitarian perspective. The valuation model shows that the inclusion of the other emissions reduces the benefit associated with CCS. For a lower CO2 price the valuation model shows that CCS is detrimental to the environment. The cost benefit analysis shows that a CO2 price of at least $80/tCO2 is required for the cost benefit ratio to be 1. The methodology integrates Montecarlo simulation to characterize the uncertainties associated with the valuation models. / Dissertation/Thesis / sima pro / excel sheets / M.S. Civil and Environmental Engineering 2012

A injeção de carvão pulverizado (PCI — pulverized coal injection) nos altos-fornos (AFs) é uma tecnologia utilizada pelas usinas siderúrgicas para aumentar a produtividade e diminuir o consumo de coque no AF. Nas últimas décadas as taxas de injeção de carvão pulverizado aumentaram na maior parte dos AFs. O principal problema associado à utilização de altas taxas de PCI é a geração de char (carvão incombusto) na zona de combustão. Este material percorre um caminho ascendente junto ao fluxo gasoso, podendo acumular-se e assim prejudicar a permeabilidade do AF. A presença, nas amostras sólidas recolhidas do gás de saída do AF, de altos teores de char pode ser o resultado da injeção de um carvão pulverizado com uma combustibilidade inadequada e de uma operação instável do AF. Portanto, conhecer a proporção de char que sai do AF contribuirá na seleção do tipo de carvão utilizado e na otimização da prática de PCI. Análises químicas das amostras de pó do AF revelam, sem distinguir, a presença de materiais carbonosos. A microscopia ótica foi utilizada para estudar estas amostras sólidas, mas apresenta certas limitações. A difração de raios-X (DRX) é uma técnica padrão para caracterizar a estrutura cristalina dos materiais. Ela também pode ser utilizada para quantificar as dimensões dos cristalitos (Lc, La, etc.) dos materiais carbonosos. Uma vez que a estrutura do coque é mais ordenada que a do char, seria possível quantificar a proporção destes materiais nas amostras de pó do AF através da DRX combinada a análises químicas. O objetivo principal deste trabalho foi identificar e quantificar os componentes carbonosos (char e finos de coque) presentes no pó de balão (PB) do AF, por DRX e análise elementar de carbono. O efeito da temperatura sobre a grafitização do coque também foi avaliado, a fim de identificar a possível origem dos finos de coque gerados no AF. Três amostras de PB coletadas de um AF, uma em operação a coque e duas a PCI, foram selecionadas. Os pós foram fracionados e analisados quimicamente. Após, as frações destas amostras foram moídas, desmineralizadas e analisadas por DRX e análise elementar de carbono. Amostras de char produzidas em laboratório e respectivos carvões foram utilizados como padrões para a quantificação. Amostras de coque foram tratadas termicamente a diferentes temperaturas, sendo posteriormente analisadas por DRX. Este estudo mostrou que a DRX pode ser usada como técnica padrão para identificar as estruturas do char e do coque podendo ser utilizada para quantificar a proporção destes materiais carbonosos no pó de balão do AF. Além disto, observou-se que quanto maior a temperatura de tratamento térmico mais ordenada fica a estrutura cristalina do coque. / In a Blast Furnace (BF), Pulverized coal injection (PCI) is the most popular injection technology used worldwide to reduce coke consumption and to increase the productivity. In the last decades the PCI injection rates raised in the most of BFs. One of the problems during the PCI operation in BF is the unburnt char formation. Higher char levels in the BF stack could impact burden permeability. The off gas BF solid samples contain char, coke fines, metallic oxides, etc. The quantification of the carbonaceous materials content in these samples could be used to improve the PCI performance in operating BF. Chemical analysis in the BF dust samples reveal without differentiates some carbonaceous material. The optical microscopy was used to study these solid samples but with some restrictions. XRD (X-ray diffraction) is a standard means of characterizing the structure of materials. This technique has been utilized to determine the crystallite sizes (Lc, La, etc.), in carbonaceous materials. Since the coke structure is more ordered than the char structure, it would be possible to quantify the proportion of these materials in the off-gas BF samples by chemical analysis in combination with XRD. The aim of this work is to identify and quantify carbonaceous components (coal, char and coke fines) in the flue dust BF samples through the use of the XRD technique and ultimate analysis. Besides, the effect of temperature on coke graphitization will be studied aiming to identify the possible origin of coke fines in the BF dust. Four dusts collected in the off-gas BF, two at all coke and two at PCI operations, were selected for this investigation. The dusts were fractioned and chemically analyzed. After the fractions were grounded, demineralized and analyzed by ultimate analysis and XRD. Besides, were investigated the atomic structure of raw coals and its laboratory char, and raw coke and its laboratory heattreated samples. This study has shown that the XRD technique could be used as a standard procedure to identify the char and coke structures and could be used to quantify the fines proportions of these carbonaceous materials in the BF flue dust. It was concluded that the bigger the annealing temperature the more ordered becomes the atomic coke structure.

A injeção de carvão pulverizado (PCI — pulverized coal injection) nos altos-fornos (AFs) é uma tecnologia utilizada pelas usinas siderúrgicas para aumentar a produtividade e diminuir o consumo de coque no AF. Nas últimas décadas as taxas de injeção de carvão pulverizado aumentaram na maior parte dos AFs. O principal problema associado à utilização de altas taxas de PCI é a geração de char (carvão incombusto) na zona de combustão. Este material percorre um caminho ascendente junto ao fluxo gasoso, podendo acumular-se e assim prejudicar a permeabilidade do AF. A presença, nas amostras sólidas recolhidas do gás de saída do AF, de altos teores de char pode ser o resultado da injeção de um carvão pulverizado com uma combustibilidade inadequada e de uma operação instável do AF. Portanto, conhecer a proporção de char que sai do AF contribuirá na seleção do tipo de carvão utilizado e na otimização da prática de PCI. Análises químicas das amostras de pó do AF revelam, sem distinguir, a presença de materiais carbonosos. A microscopia ótica foi utilizada para estudar estas amostras sólidas, mas apresenta certas limitações. A difração de raios-X (DRX) é uma técnica padrão para caracterizar a estrutura cristalina dos materiais. Ela também pode ser utilizada para quantificar as dimensões dos cristalitos (Lc, La, etc.) dos materiais carbonosos. Uma vez que a estrutura do coque é mais ordenada que a do char, seria possível quantificar a proporção destes materiais nas amostras de pó do AF através da DRX combinada a análises químicas. O objetivo principal deste trabalho foi identificar e quantificar os componentes carbonosos (char e finos de coque) presentes no pó de balão (PB) do AF, por DRX e análise elementar de carbono. O efeito da temperatura sobre a grafitização do coque também foi avaliado, a fim de identificar a possível origem dos finos de coque gerados no AF. Três amostras de PB coletadas de um AF, uma em operação a coque e duas a PCI, foram selecionadas. Os pós foram fracionados e analisados quimicamente. Após, as frações destas amostras foram moídas, desmineralizadas e analisadas por DRX e análise elementar de carbono. Amostras de char produzidas em laboratório e respectivos carvões foram utilizados como padrões para a quantificação. Amostras de coque foram tratadas termicamente a diferentes temperaturas, sendo posteriormente analisadas por DRX. Este estudo mostrou que a DRX pode ser usada como técnica padrão para identificar as estruturas do char e do coque podendo ser utilizada para quantificar a proporção destes materiais carbonosos no pó de balão do AF. Além disto, observou-se que quanto maior a temperatura de tratamento térmico mais ordenada fica a estrutura cristalina do coque. / In a Blast Furnace (BF), Pulverized coal injection (PCI) is the most popular injection technology used worldwide to reduce coke consumption and to increase the productivity. In the last decades the PCI injection rates raised in the most of BFs. One of the problems during the PCI operation in BF is the unburnt char formation. Higher char levels in the BF stack could impact burden permeability. The off gas BF solid samples contain char, coke fines, metallic oxides, etc. The quantification of the carbonaceous materials content in these samples could be used to improve the PCI performance in operating BF. Chemical analysis in the BF dust samples reveal without differentiates some carbonaceous material. The optical microscopy was used to study these solid samples but with some restrictions. XRD (X-ray diffraction) is a standard means of characterizing the structure of materials. This technique has been utilized to determine the crystallite sizes (Lc, La, etc.), in carbonaceous materials. Since the coke structure is more ordered than the char structure, it would be possible to quantify the proportion of these materials in the off-gas BF samples by chemical analysis in combination with XRD. The aim of this work is to identify and quantify carbonaceous components (coal, char and coke fines) in the flue dust BF samples through the use of the XRD technique and ultimate analysis. Besides, the effect of temperature on coke graphitization will be studied aiming to identify the possible origin of coke fines in the BF dust. Four dusts collected in the off-gas BF, two at all coke and two at PCI operations, were selected for this investigation. The dusts were fractioned and chemically analyzed. After the fractions were grounded, demineralized and analyzed by ultimate analysis and XRD. Besides, were investigated the atomic structure of raw coals and its laboratory char, and raw coke and its laboratory heattreated samples. This study has shown that the XRD technique could be used as a standard procedure to identify the char and coke structures and could be used to quantify the fines proportions of these carbonaceous materials in the BF flue dust. It was concluded that the bigger the annealing temperature the more ordered becomes the atomic coke structure.