Caracteriza??o tecnol?gica de misturas de ?sinter-feed? e ?pellet-feed? empregando diferentes rotas de sinteriza??o em escala piloto.

Programa de P?s-Gradua??o em Engenharia de Materiais. Departamento de Engenharia Metal?rgica, Escola de Minas, Universidade Federal de Ouro Preto.Com a corrente transi??o dos dep?sitos minerais de ferro de hemat?ticos para itabir?ticos e goeth?ticos no quadril?tero ferr?fero, o split de produtos do beneficiamento de jazidas vem se alterando. As participa??es de min?rios granulados e sinter feed vem se reduzindo com passar do tempo com o proporcional aumento da gera??o de pellet feed. Este fato se deve principalmente a caracter?stica fri?vel dos min?rios itabir?ticos como tamb?m a necessidade de maior cominui??o do min?rio. A cominui??o ? necess?ria para aumentar o grau de libera??o e por consequ?ncia a recupera??o met?lica em processos de concentra??o. Os sinter feeds que s?o gerados atualmente apresentam os teores de SiO2, Al2O3 e P mais elevados. Tem sido pr?tica das mineradoras aumentar a participa??o de pellet feed blendados com sinter feeds para adequa??o da qualidade qu?mica. Com esta a??o, o aumento de finos na mistura de min?rios ? inevit?vel e por consequ?ncia, a etapa de aglomera??o a frio do processo de sinteriza??o passa a ser mais exigida para manuten??o dos n?veis de produtividade e qualidade do s?nter. Logo, a siderurgia nacional necessita de solu??es que possibilitem a manuten??o de performance e qualidade do s?nter em mistura com elevadas participa??es de finos, pois na grande maioria das sider?rgicas integradas, o s?nter ainda ? a principal carga met?lica utilizada. Uma mudan?a dr?stica deste cen?rio implicaria na obsolesc?ncia da maioria das sinteriza??es, por ainda n?o estar apropriada a manusear grandes quantidades de pellet feed na mistura de min?rios. O objetivo do presente estudo foi desenvolver uma rota tecnol?gica conceitual, considerando concep??es operacionais, layouts e tecnologias de mistura e noduliza??o que propiciassem a utiliza??o de finos (% <0,150mm) na mistura de min?rios em patamares acima dos 40%, consolidados industrialmente pela tecnologia HPS. Para a avalia??o e verifica??o das hip?teses consideradas durante o desenvolvimento do estudo, uma s?rie de experimentos em escala piloto foram realizadas, simulando principalmente a etapa de prepara??o do processo de sinteriza??o (homogeneiza??o e granula??o). Os melhores resultados destas simula??es foram submetidos a avalia??es a quente utilizando o pot grate para verifica??o dos impactos operacionais, poss?veis dificuldades de processo, produtividade e qualidade do s?nter produzido, comparando os resultados obtidos com os resultados referentes da tecnologia HPS, refer?ncia deste estudo. Dentre as possibilidades avaliadas, a rota utilizando disco (trabalhando em paralelo com o misturador e nodulizador tambor) atingiu 60% de participa??o de finos na mistura de min?rios, com condi??es satisfat?rias de processo e produtividade. Os resultados obtidos, considerando 80% de finos, ainda carece de ajustes, pois apresentou grande instabilidade do processo, principalmente em rela??o ? qualidade f?sica do s?nter produzido.With current mineral deposit change of hematite to itabirite and goethitc in the Iron Ore Quadrangle, the split of beneficiation products have been change over the time. The participation of lump ore and sinter feed has reducing with proportional increasing of pellet feed generation. This fact whether mainly because of crumbly characteristic of the itabirite iron ores as well the need of further comminution of the ore to increase of release degree and consequently the metallic recovery. The quality of the sinter feed that are still generated no shows quality as in the past, mainly SiO2 content, Al2O3 and P is much higher and has been practiced of Mines increasing the pellet to participation of pellet feed for performing chemical sinter feed correction currently produced. With this action, the fines increase in the iron ore mix is inevitable and by consequence, the agglomeration step of sintering process it becomes more required to maintain the productivity level and quality of sinter that feed the reactors. Therefore, the national steel industry urgently needs of one solution that gives the possibility to increase considerable the fines participation in the ore mix without impacts in the productivity level and quality of sinter. At the national steel industry, the sinter is the main metallic burden used and a drastic change in this scenario will result in the obsolescence of the most sintering plants of the national steel industry, for not being suitable to handle large proportions of pellet feed(fines) in the ore mix. The purpose of this study was to develop a technological concept of a route, considering the operational possibilities, layouts and mix and nodulizing that would result in the fines usage higher than 40% as was industrial consolidated by HPS technology. To evaluate and certificate the considered hypothesis during the study development, a series of simulations were performed, simulating mainly the mix preparation step (homogenization and nodulation) were done together with the cold permeability evaluation on the bed resulted of the preparation step. The best results of these simulations were submitted to the sinter pot grate evaluation to verify the operational impacts, some process problems, productivity and quality of the sinter produced, comparing the obtained results with the HPS references. Among the possibilities evaluated, the route using the disk working in parallel with the mixer and drum nodulizer reached a 60% share of fines in the ore mixture, with satisfactory conditions of process and productivity. The results obtained considering 80% of fines still lack adjustments, since it presented instability of the process, mainly in relation to the physical quality of the sinter produced. Therefore, exceeding 40% of fines in the ore mixture was possible, with beneficial results, mainly the chemical quality of the sinter. In order to obtain values higher than 60%, it is necessary to optimize the fuel dosage and the effect of the form factor (spherical particles) on the matrix consolidation process and on the influence of these conditions, mainly the physical quality of the sinter produced

Pelletizing furnace refractory lining life cycle extension by applying thermography analysis and direct refractory injection.

The induration furnace is one of the most important devices in the pellet production system. It is responsible for ensuring the quality of pellets produced, since a high level of thermal energy is necessary to reach the physical properties needed. Therefore, the refractory lining performance is important to guarantee the quality of pellets and to avoid thermal losses. Minor failures in the refractory lining may result in serious damage, if it not previously identified and repaired. This article was written to explain a preventive technique to identify and repair such minor issues with the refractory lining before escalation. The use of this technique in the proper frequency may result in furnace life cycle extension

Analisando as pesquisas em educação especial no Brasil Analysing research in special education in Brazil

Nosso objetivo foi examinar a articulação lógica entre o problema e a proposição teórico-metodológica das produções na área da Educação Especial, focando os seus pressupostos epistemológicos. Nos fundamentamos nos pressupostos das tendências empírico-analítica, fenomenológica-hermenêutica, crítico-dialética e do paradigma da complexidade. O procedimento adotado foi interpretar todas as dissertações/teses produzidas nos Programas de Pós-Graduação em Educação e Educação Especial do Brasil, que versam sobre Educação Especial, produzidas nos anos de 2001, 2002 e 2003, disponíveis no banco de teses da CAPES. Encontramos as tendências empírica, fenomenológica e dialética. Os equívocos encontrados foram a não inserção da pesquisa entre as produções na área; ausência de criticidade; não posicionamento numa determinada concepção de educação; construção teórica fundamentada em concepções diferentes; falta de coerência nos pressupostos teórico-metodológicos; não explicitação metodológica; não descrição dos procedimentos éticos; e má elaboração dos resumos. Concluímos pela necessidade da melhoria das dissertações/teses para que possamos avançar na produção de conhecimento na área da Educação Especial.<br>Our objective was to analyze the logical articulation between the problem and the theoretical-methodological proposal of studies in the field of Special Education, focusing on the epistemological issues. We based our study on the empiric-analytical tendencies, phenomenology-hermeneutic, critical-dialectical and the complexity paradigm. The procedure that was adopted was interpreting all dissertations/thesis produced in Post-Graduate programs in Education and Special Education in Brazil, which focus on Special Education, produced in 2001, 2002 and 2003, available online at CAPES' thesis database. We found empirical, phenomenological and dialectic tendencies. The errors encountered included the failure to include the research among the productions in the field; lack of critical approach; lack of making explicit what educational conception the study was based on; theoretical construction based on different conceptions; lack of coherence in the theoretical-methodological proposals; lack of methodological specification; absence of ethical procedural descriptions; and poorly written abstracts. We came to the conclusion that improvements in theses /dissertations are necessary so as to continually move forward in the production of knowledge in the field of Special Education

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data

Proceedings Of The 23Rd Paediatric Rheumatology European Society Congress: Part Two

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