An experimental study was undertaken to quantify the rate of DRI decarburization in a steelmaking slag using the constant–volume pressure increase technique. Experiments were conducted by dropping DRI pellets into molten slag at temperatures from 1500°C to 1600°C. Further experiments were carried out in which the DRI pellets were preheated while the slag temperature remained constant. The effect of initial carbon content and preheating temperature of the DRI on the reaction rate was investigated. The decarburization of DRI appears to comprise of two stages; reaction with the FeO of DRI, followed by further decarburization through the iron oxide of slag. Carbon has a significant effect on the kinetics of both stages while the preheating temperature mainly influences the rate of the reaction between FeO and carbon inside the pellet.

An experimental study was undertaken to quantify the rate of DRI decarburization in a steelmaking slag using the constant–volume pressure increase technique. Experiments were conducted by dropping DRI pellets into molten slag at temperatures from 1500°C to 1600°C. Further experiments were carried out in which the DRI pellets were preheated while the slag temperature remained constant. The effect of initial carbon content and preheating temperature of the DRI on the reaction rate was investigated. The decarburization of DRI appears to comprise of two stages; reaction with the FeO of DRI, followed by further decarburization through the iron oxide of slag. Carbon has a significant effect on the kinetics of both stages while the preheating temperature mainly influences the rate of the reaction between FeO and carbon inside the pellet.

Made available in DSpace on 2014-06-12T23:01:26Z (GMT). No. of bitstreams: 2 arquivo8554_1.pdf: 933358 bytes, checksum: 57664669405f134c0abc5de236b2d8c7 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Universidade Federal de Alagoas / Esta dissertação propõe-se avaliar o consumo de energia e proteínas e associá-lo ao estado nutricional de crianças menores de cinco anos, no Estado de Pernambuco no ano de 1997. Está estruturada em dois artigos, o primeiro constituindo uma revisão da literatura sobre os principais inquéritos epidemiológicos alimentares e nutricionais realizados no Brasil a partir da década de 40 até os dias atuais, abordando seus aspectos metodológicos, bem como os resultados mais relevantes. Os dados foram coletados utilizando as bases de dados Scielo e Lilacs, além de livros e relatórios oficiais acerca dos estudos populacionais. O consumo alimentar e o estado nutricional das crianças de até cinco anos constituíram o campo de estudo do segundo artigo, com desenho do tipo transversal e amostra de 948 crianças. O consumo alimentar foi registrado utilizando-se o método recordatório de 24 horas. Para análise do consumo de energia e proteína foram utilizadas as Dietary Reference Intakes como referência. O estado nutricional foi avaliado por meio dos índices de peso/idade, peso/estatura e estatura/idade, em médias de escores Z, utilizando as medidas do National Center for Health Statistics como referência. O consumo mediano de energia e proteína esteve acima das ingestões dietéticas de referência, na maioria das faixas etárias. No entanto, foram encontradas prevalências de inadequação de 42,4% para energia e de 5% para proteína. O percentual de desnutrição moderada e grave foi de 7,3%, 1,5% e 16,1% para os índices peso/idade, peso/estatura e estatura/idade, respectivamente. O estado nutricional foi melhor no grupo de crianças cujo consumo de energia e proteína foi maior ou igual ao padrão de referência, na maioria das faixas etárias. Os resultados do estudo assinalam uma acentuada restrição da ingestão de energia e, em menor dimensão, de proteínas. Foi demonstrada também uma associação entre o consumo energético-protéico e o estado nutricional das crianças, ratificando que o consumo alimentar é um dos fatores que influenciam o estado nutricional. Conclui-se então que é necessário monitorar o consumo alimentar, o que poderá ser efetivado com a implantação de políticas de segurança alimentar e nutricional que visem melhorar a situação alimentar e nutricional das crianças nesta faixa etária

The drone industry is growing and the need for increased autonomy will be required if large fleetof drones will be able to fly without a single pilot per drone. A useful part of automating the flighten-route can be achieved with the upcoming standard of Direct Remote Id (DRI), which signalspositional data for drones and can be used as the perceptive part in a collision avoidance systembetween drones with the advantage of limited weight penalties and minimal financial cost.Simulations were carried out to understand different kinds of evasive maneuvers and develop asimple yet effective algorithm for avoiding obstacles and continue towards the next waypoint ona mission. Positional data can be retrieved with an ESP-32 board from a flight computer withMavlink protocol, which can then be broadcasted and received to an ESP-32 board using DirectRemote Id. The distances between the nearest drones can be computed, along with the shortest al-lowable distance and closest positions of the drones, if they were to continue on a straight course. Ifthe closest passing distance turned out closer than a set safety distance, an evasive maneuver is cal-culated and executed, with preliminary work focusing on evasion maneuvers on an horizontal plane.Flight tests showed that an evasive position could be calculated, and the drone successfully di-verted to it, while continuing with the mission after the evasion was completed. These resultsshowed the potential of using Direct Remote Id as a simple close proximity detection for use withcollision avoidance / Drönarindustrin växer allt snabbare och det kommer att krävas en större grad av autonomitet för att kunna få drönare att flyga av sig själva utan att ha en pilot per drönare. En användbar del av att kunna autonomisera flygrutten vid flykt kan vara den nya standarden Direct Remote Id (DRI), som sänder ut positionsdata för den individuella drönaren och kan användas för att kunna upptäcka och bli upptäckt av andra drönare med minimal vikt- och priskostnad.Simuleringar gjordes för att undersöka samt förstå olika typer av undanmanövrar och för att utveckla en simpel och effektiv algoritm för att kunna undvika objekt och fortsätta med en planerad rutt. Positionsdata kan skickas till ett ESP-32 kretskort fån en flygdator med hjälp av Mavlink protokoll, denna data kan sedan sändas och bli mottaget av ett annat ESP-32 kretskort med Direct Remote Id standarden. Avståndet till den närmsta drönaren kan beräknas samt den minsta passagedistansen mellan drönarna om de skulle fortsätta i rak riktning. Om den minsta passagedistansen mellan drönarna är mindre än ett satt säkerhetsavstånd, beräknas en undanmanöver samt utförs. Flygtester visade att en undanmanöver kunde beräknas samt att drönaren omdirigerades till sidan om objektet och därefter fortsatte på sin planerade flygrutt. Dessa resultat visade potentialen i att använda Direct Remote Id som ett enkelt sätt att upptäcka andra drönare för att användas i ett kollisionsundvikande system.

[pt] A produção e o uso de DRI (Direct Reduction Iron) são cada vez maiores hoje em dia nos países desenvolvidos, essencialmente pela redução do preço do gás natural e do sucesso da tecnologia de extração de gás de xisto. Além disso, o menor teor de elementos contaminantes em DRI do que nas sucatas de aço, levou-o a ser considerado uma boa alternativa como carga metálica para o Forno Elétrico a Arco (FEA) e o processo no conversor LD /BOF. Os custos operacionais e os problemas ambientais, são atualmente dois fatores tecnológicos importantes a serem considerados na otimização da produção de DRI, afetando à produtividade, sustentabilidade e competitividade do processo industrial. O teor de carbono do DRI, por exemplo, tem se tornado cada vez mais importante, devido à sua capacidade de gerar energia química nas aciarias, complementando o uso de energia elétrica nos FEA e os inputs energéticos no LD. Este trabalho foi uma das partes do programa de cooperação entre a Companhia de Mineração Samarco e o Grupo de Siderurgia da Pontifícia Universidade Católica do Rio de Janeiro / PUC-Rio, que tratou especificamente do modelo cinético para a metalização e carburização simultâneas em fornos RD tipo cuba. No âmbito deste objetivo o reator foi dividido em três zonas: Redução, Transição e Resfriamento. Foram também consideradas mais três camadas concêntricas: periférica, media e central. Com base nos resultados obtidos em experiências que abrangeram diferentes tipos de pelotas, empregando misturas gasosas semelhantes às presentes nos processos industriais e obedecendo às suas correspondentes semelhanças fluidodinâmicas, foi desenvolvido um software, denominado METCARB, que incluiu na sua elaboração todas as equações e modelos cinéticos desenvolvidos experimentalmente nas três zonas do reator RD. A parte experimental foi, portanto, uma das partes principais do presente trabalho, conjuntamente com a concepção do modelo computacional e suas validações industriais. Com o METCARB, as previsões acerca da metalização e carburização simultâneas, em qualquer região interna do forno, se tornou possível, utilizando como entradas as dimensões do forno, medidas de temperaturas, composições dos gases, etc. Os resultados de metalização e carburização, também em formato gráfico, são gerados pelo sistema computacional, bem como as curvas cronométricas e tabelas de resultados. Estudos sobre dois casos reais foram realizados, a fim de validarem a ferramenta computacional desenvolvida. Constatou-se que a carburização do ferro metálico sempre ocorre simultaneamente com a redução dos óxidos de ferro e que, dependendo da temperatura e composição dos gases, pode ocorrer precipitação de finos de carbono. As simulações realizadas com o modelo METCARB mostraram que na periferia da ZR é gerado um DRI mais metalizado que na região do centro. Fenômeno contrário foi, entretanto, verificado com a carburização; Nas condições experimentais empregadas neste trabalho, os valores médios obtidos para a carburização e a metalização, no final da ZR, variam entre 0,4 - 0,7 por cento C, e 92 por cento - 97 por cento, respectivamente; Constatou-se não ocorrer progresso do grau de redução nas zonas de Transição (ZT) e de Arrefecimento (ZA), ou seja, mantiveram-se ao longo dessas zonas os valores de metalização obtidos no fundo da ZR; A influência do vapor de água no processo da carburização no caso estudado (0 - 4.25 por cento H2O) leva menor porcentagem de carburização (2,7 por cento C – 2,35). / [en] The production and the use of DRI (Direct Reduction Iron) are increasing today in developed countries, mainly by reducing the price of natural gas and the success of shale gas extraction technology. In addition, the lower level of contaminants in DRI than in metal scraps, led it to be considered a good alternative as metallic charge for the Electric Arc Furnace (EAF) and the process in LD / BOF converter. This work was one part of the cooperation program between Samarco Mining Company and Steel Group of the Pontifical Catholic University of Rio de Janeiro / PUC-Rio, which specifically dealt with the kinetic model for the metallization and carburization simultaneous in RD shaft furnaces. Under this purpose the reactor was divided into three zones: Reduction, Transition and Cooling. There were also three concentric regions considered: peripheral, media and center. Based on the results from experiments covering different types of pellets, using gas mixtures similar to those present in the industrial processes and obeying their corresponding fluid dynamic similarities, it developed a software called METCARB, which included in its preparation all kinetic equations and models developed experimentally in the three reactor zones of RD. The experimental part was therefore a major part of this work, together with the design of computational model and its industrial validations. With METCARB predictions about the simultaneous metallization and carburization in any internal region of the furnaces, it became possible, using as inputs the dimensions of the furnace, temperature measurements, compositions of gases, etc. The results of metallization and carburization also in graphic format are generated by the computer system, and the chronometric curves and results tables. Studies on two real cases were performed in order to validate the developed computational tool. It was found that the carburization always occurs simultaneously with the reduction of iron oxides and, depending on the temperature and composition of the gases; precipitation of fine carbon may occur. The simulations with METCARB model showed that the periphery of the ZR generated more DRI metallized than the center area. A contrary phenomenon has been verified with the carburization; With the experimental conditions used in this study, averages values obtained for the metallization and carburization in the final ZR vary between 0.4 - 0.7 percent C and 92 percent - 97 percent, respectively; It was not found that the progress of reduction degree occurred in the transition (ZT) and cooling (ZA) regions, in other words, it remained along these zones of the metallization values obtained at the bottom of ZR; The influence of water vapor in the carburization process in the case studies (0 - 4.25 percent H 2 O) takes a smaller percentage of carburization (2.7 percent C - 2.35).

Direct Reduced Iron (DRI) is used as an alternative feedstock in electric arc furnaces, making up 50% or more of the total iron charge. DRI produced with coal based reductants (for example in rotary kilns) make up roughly 25% of DRI produced in the world. It was found that SL/RN DRI samples from a kiln cooler had high nitrogen contents (50-250ppm, depending on particle size), higher than DRI from gas-based reduction. The higher nitrogen content of SL/RN DRI would increase the levels of nitrogen of liquid steel produced in the EAFs. The problem is exacerbated by the fact that the SL/RN DRI contains virtually no carbon (which would aid in preventing nitrogen pickup). The proposed mechanism of nitrogen pick-up by the SL/RN DRI is one where nitrogen present within the atmosphere of the rotary cooler (where hot DRI, discharged at 1000°C from the rotary kiln, is cooled to approximately 100 °C in ca. two hours) penetrates the solids bed and nitrides DRI particles. Possible rate-determining steps for nitriding in the cooler have been evaluated. Nitriding of DRI particles is predicted to be rapid: the most plausible location for rapid nitrogen pickup is the first 5 meters of the rotary cooler, where the high temperature, nitrogen-rich gas atmosphere and rapid solids bed mixing are conducive to nitriding; solid-state and pore diffusion of nitrogen into DRI particles are predicted to be rapid too. The most plausible rate determining step for nitriding of DRI particles is that of nitrogen dissociation on the DRI surface, which can be further retarded by the presence of sulphur. A strong correlation was found between the amount of “melt-in” carbon in the liquid steel and the final tap nitrogen content, with 0.3% C resulting in nitrogen levels as low as 50 ppm (80 ppm or less is desired on the plant in question) at tap, even with DRI material that is high in nitrogen and contains virtually no carbon. Proposals to increase the melt-in carbon are included. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Materials Science and Metallurgical Engineering / unrestricted

Bei der Herstellung von direkt reduziertem Eisen im Midrex-Direktreduktionsprozess fallen zahlreiche eisenhaltige, feinkörnige Hüttenreststoffe an. Um eine Deponierung der Reststoffe zu vermeiden wurden zwei verschiedene Varianten zur Aufbereitung dieser Reststoffe durch Brikettierung anhand von Laborversuchen erprobt und hinsichtlich ihrer resultierenden Eigenschaften bewertet. Variante I umfasst die Brikettierung der Reststoffe zum erneuten Einsatz als Ausgangsmaterial im Midrex-Direktreduktionsprozess. Variante II untersucht die Einbindung der Reststoffe bei der ohnehin stattfindenen Heißbrikettierung der reduzierten Pellets zu heiß brikettiertem Eisen (HBI). Die vorliegende Arbeit zeigt für beide Varianten, dass mit geeigneten Mischungszusammensetzungen und Brikettierbedingungen Briketts mit ausreichenden mechanischen, thermischen und metallurgischen Eigenschaften hergestellt werden können. Die zugrunde liegenden Bindemechanismen werden anhand von optischer Mikroskopie, Vickershärtebestimmungen und REM/EDX-Untersuchungen qualitativ beurteilt.:1 Einleitung 2 Stand der Technik 2.1 Direktreduktion, Midrex-Prozess und Reststoffproblematik 2.2 Agglomeration von eisenhaltigen Reststoffen und Feinerzen 2.2.1 Brikettierung von Hüttenreststoffen aus dem Midrex-Prozess 2.2.2 Brikettierung von Reststoffen aus dem Hochofen 2.2.3 Aufbauagglomeration von Feinerzen 2.2.4 Sintern von Feinerzen 2.2.5 Auswahl einer geeigneten Agglomerationsmethode 2.2.6 Anforderungen an die Briketts für den Einsatz im Midrex-Prozess 2.2.7 Anforderungen an HBI-Briketts 2.3 Zielstellung 3 Anwendungsbezogene Grundlagen 3.1 Bindemechanismen 3.2 Pressverdichtung 3.3 Bindemittel 3.3.1 Vorbemerkungen 3.3.2 Bentonit 3.3.3 Stärke und Cellulose 3.3.4 Sulfitablaugen 3.3.5 Zement 3.3.6 Löschkalk 4 Versuchsaufbau und Versuchsdurchführung 4.1 Charakterisierung des Einsatzmaterials und der Bindemittel 4.1.1 Hüttenreststoffe 4.1.2 Eisenerzpellets 4.1.3 DRI-Pellets 4.1.4 Bindemittel 4.2 Brikettierung mit Bindemittel 4.2.1 Statistische Versuchsplanung 4.2.2 Mischen 4.2.3 Vorwärmen 4.2.4 Brikettieren 4.2.5 Aushärten und Lagerung 4.2.6 Mechanische und metallurgische Beurteilung der Briketts 4.3 Heißbrikettierung 4.3.1 Mischen 4.3.2 Aufheizen 4.3.3 Brikettieren 4.3.4 Beurteilung der Briketteigenschaften 4.4 Betrachtung der Bindemechanismen 5 Ergebnisse und Diskussion 5.1 Brikettierung der Reststoffmischung mit Bindemitteln (Variante I a) 5.1.1 Mechanische Eigenschaften der Briketts 5.1.2 Metallurgische Eigenschaften der Briketts 5.1.3 Chemische Eigenschaften der Reststoffbriketts mit Bindemittel 5.1.4 Zusammenfassung Brikettierung mit Bindemitteln 5.2 Heißbrikettierung der Reststoffmischung (Variante I b) 5.2.1 Einfluss der Mischungszusammensetzung 5.2.2 Einfluss der Pressbedingungen 5.2.3 Mikroskopische Betrachtung 5.2.4 Zusammenfassung Heißbrikettierung der Reststoffmischung 5.3 Gemeinsame Brikettierung der Reststoffmischung mit DRI-Pellets (Variante II) 5.3.1 Einfluss der Reststoffmischung auf die HBI Qualität 5.3.2 Einfluss der Pressbedingungen (Vorwärmtemperatur, Pressdruck) 5.3.3 Mikroskopische Betrachtung 5.3.4 Zusammenfassung Brikettierung Reststoffmischung mit DRI-Pellets 5.4 Beurteilung der Methoden zur Klärung der Bindemechanismen 5.5 Vergleichende Beurteilung der verschiedenen Verwertungsvarianten 6 Zusammenfassung und Ausblick 7 Literaturverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Abkürzungs- und Symbolverzeichnis Anhang

The thesis develops and documents a workflow for applying TRANSIMS to the analysis of Developments of Regional Impact (DRI). The proposed workflow will consider perspectives of both the transportation agency responsible for the evaluating the DRI and the transportation engineer responsible for performing the analysis. TRANSIMS offers a comprehensive framework for managing inputs and outputs that follow a transportation planning workflow. Not a single, monolithic software application, TRANSIMS is a suite of 65 small, light-weight, single-task tools for creating and manipulating GIS shape files and SQL data base files, estimating the elements of a four-step transportation modeling process, and computing link and vehicle delays for a given transportation network. Current analysis techniques for developments of regional impact require that the analyst apply arbitrary or non-repeatible estimates for trip assignments at the regional level. Because of the modular nature of the TRANSIMS, implementing each DRI as a layer in the GIS data base will permit the mixing and matching of multiple DRI within a local area, permitting a risk-based approach to the evaluation of multiple DRI, any of which may or may not actually happen. This thesis focuses exclusively on the review of DRI analysis techniques, review of TRANSIMS modules, and development of a proposed DRI workflow within the TRANSIMS framework.

[pt] O presente trabalho apresenta uma análise do fenômeno de carburização na zona de redução de um forno de cuba tipo Midrex. É realizada uma análise dos principias trabalhos existentes na literatura, é apresentado o aparato experimental, a caracterização das amostras e os resultados obtidos. Os experimentos foram efetuados com o auxilio da ferramenta estatística denominada planejamento fatorial. O tempo dos experimentos foi variado, simulando a operação industrial, com a finalidade de obter o equacionamento cinético. A função obtida foi não linear, envolvendo uma função transcendental, a qual melhor se ajustou aos pontos experimentais. A partir destes resultados foi efetuado uma análise termodinâmica das reações de carburização mais provaveis da zona de redução e determinados os parâmetros cinéticos da carburização. Estes ultimos foram: fator temporal, Tau de 1,32 h, tempo de incubação de 0,30 h, para 500 ºC, e 0,80 h para 900 ºC; fator de carbono de saturação A para 500 ºC com vazão de 60 NL/min foi de 2,70 %, com 90 NL/min de 3,46%; para 900 ºC com 60 NL/min foi 0,10 % e para 90 NL/min de 0,16%. Finalmente, os calculos das velocidades iniciais do processo de carburização foram de 2,3 %C.h-1, para 500 ºC e 0,10 %C.h-1 a 900ºC, para uma fração carburante de 0,37. Os resultados mostraram que o conteúdo de carbono no ferro esponja, obtido nesta zona para as condições reais do processo, alcançou uma média de 0,043 %C, fato de relevante importância para os processos de redução direta em forno de cuba. / [en] In this work an analysis of the carburation phenomena in the reduction zone of the type Midrex Furnace is presented. A revue of the principal papers found on the subject`s literature is followed by the description of the laboratory apparatus, sample characterization, and finally, the obtained experimental results are presented. The experimental planning and screening for this work was defined by a factorial analysis. Further the residence times for all experiments were defined to simulate the actual furnace industrial operation. Also, the experiments aimed at the determination of the parameters belonging to mathematical transcendental formulae designed to simulate the furnace`s charge behavior. Based upon the results, a thermodynamical analysis was conducted obeying the operational conditions inside the furnace, this to determine all the viable carburation reactions. The analysis was followed by kinetic evaluations that produced the data for the carburation process exponential formula parameters determination, namely exponential time factor = 1,32 h; incubation time, 0,30 h at 500 oC and 0,80 h at 900 oC and carbon saturation factor A, ranging from 2,7 % for a gas flow rate of 60 NLmin-1, 3,6 % for a gas flow rate of 90 NLmin-1 to 500 oC and 0,10 % for a gas flow rate of 60 NLmin-1, 0,16 for a flow rate of 90 NLmin-1 to 900 oC. Besides, the initial carburation rates were determined for atmospheres having carburating ratios of 0,37, and they measured 2,3 %C.h-1 for 500 ºC and 0,10 %C.h-1 for 900 ºC. Wrapping up the results this work showed that an average of 0,043 %C in the DRI is to be expected in the reducing zone for the actual industrial conditions.

No description available.