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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Determina??o da mat?ria mineral por tratamento t?rmico e dos teores de formas de enxofre por peroxida??o do carv?o brasileiro

Fallavena, Vera Lucia Vargas 28 November 2011 (has links)
Made available in DSpace on 2015-04-14T13:58:44Z (GMT). No. of bitstreams: 1 435561.pdf: 2728241 bytes, checksum: da1ed4c71f1e2687c93e62b56427d257 (MD5) Previous issue date: 2011-11-28 / The Brazilian coal has about 50% ash and high sulfur content is usually classified as a low rank. Information about the mineral and organic fractions of coal, through a series of analytical characterization techniques are essential for its sustainable use. In this study, the content of mineral matter (MM) in Brazilian coal, was obtained from the ash content of medium temperature (300?C, 400?C and 370?C) and low temperature (<200?C) with oxygen plasma (LTA) with the purpose to isolate the MM without the changes caused by high temperatures (775?C) and analyze it without the interference caused by organic matter. Due to environmental problems caused by sulfur in the coal, peroxidation was evaluated as a desulfurization process and estimation of the contents of sulfur forms in coals. The results shows that the percentage of MM obtained at 300?C and LTA are approximately 8 to 17% higher than ash contents obtained at high temperatures. The process of peroxidation in hydrochloric acid media showed to be a technique that can be applied to the desulfurization of coal by removal of 86% to 98% of pyritic sulfur. The concentration of sulphate in the extracts can be used to predict the total sulfur (&#8804; 14% error) for samples with lower relative levels of organic sulfur (<30% Stotal). The sum of the pyritic and sulfate sulfur can also be estimated from the levels of dissolved sulfate, with errors less than 14% for most of the coals studied. Measurements of iron content gives an indication of the amount of pyrite present, with an error of ?12%. / O carv?o brasileiro apresenta em m?dia 50% de cinzas e elevados teores de enxofre sendo normalmente classificado como de baixo rank. A obten??o de informa??es sobre as fra??es mineral e carbonosa do carv?o, atrav?s de uma s?rie de t?cnicas anal?ticas de caracteriza??o ? indispens?vel para o seu uso sustent?vel. Neste estudo o conte?do de mat?ria mineral (MM), em carv?es brasileiros, foi obtido do teor de cinzas a m?dia temperatura (300?C, 370oC e 400?C) e baixa temperatura (<200?C) com plasma de oxig?nio (LTA) com o intuito de isolar a MM sem as transforma??es provocadas por altas temperaturas (775?C) e analis?-la sem a interfer?ncia provocada pela mat?ria carbonosa. Devido aos problemas ambientais causados pelo enxofre presente no carv?o, a peroxida??o foi avaliada como um processo de dessulfuriza??o e estimativa dos teores das formas de enxofre em carv?es. Os resultados mostraram que os teores de MM obtidos a 300?C e LTA s?o em m?dia de 8 a 17% maiores que os teores de cinzas obtidos a altas temperaturas. O processo de peroxida??o em meio ?cido clor?drico mostrou ser uma t?cnica adequada na dessulfuriza??o do carv?o com remo??es de 86% a 98% do enxofre pir?tico. A medida da concentra??o de sulfato presente nos extratos pode ser usada na previs?o do enxofre total (erros &#8804; 14%) para amostras com menores teores relativos de enxofre org?nico (<30% Stotal). O somat?rio dos teores de enxofre pir?tico e sulf?tico podem tamb?m ser estimados ? partir dos teores de sulfato dissolvidos, com erros menores que 14% para a maioria dos carv?es estudados. As medidas de teores de ferro dissolvido podem ser utilizadas na estimativa da quantidade de enxofre pir?tico presente, com erro de ? 12%.

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