Caracteriza??o de min?rios do distrito manganes?fero de S?o Jo?o Del Rei (MG) com ?nfase no rendimento da produ??o de ferro-ligas.

Programa de P?s-Gradua??o em Engenharia Mineral. Departamento de Engenharia de Minas, Escola de Minas, Universidade Federal de Ouro Preto.Mais de 90% da produ??o mundial de mangan?s ? direcionada para consumo metal?rgico na fabrica??o de ligas, entretanto ? limitado o n?vel de conhecimento sobre as caracter?sticas geometal?rgicas desses min?rios, uma vez que essas caracter?sticas influenciam grande parte da operacionalidade dos reatores sider?rgicos. Sendo assim, o presente trabalho contempla estudos de caracteriza??o f?sica, qu?mica, mineral?gica e ensaios com respostas metal?rgicas como tamboramento e crepita??o para min?rio de mangan?s de duas minas do distrito manganes?fero de S?o Jo?o Del Rei, Totonho e Penedo. No caso dessas minas, estes estudos s?o pioneiros no que tange um aprofundamento das correla??es do tipo e qualidade do min?rio com seu comportamento metal?rgico em escala laboratorial. As amostras de min?rios de cada mina foram classificadas em global, em tr?s tipos de produtos (granulado, intermedi?rio e finos) e numa faixa granulom?trica (+19,0-6,3mm) que atende as especifica??es para fornos el?tricos a arco de redu??o (FER) segundo padr?o ISO 8731 de crepita??o, granulado ideal. As an?lises qu?micas foram feitas atrav?s de titula??o e espectrometria de emiss?o at?mica. As an?lises mineral?gicas utilizaram as t?cnicas de difra??o de raios X e para o granulado ideal tamb?m se usou a microscopia ?tica, imagens de el?trons retroespalhados (MEV) e espectroscopia por energia dispersiva (EDS). Os ensaios metal?rgicos foram adaptados das refer?ncia para min?rios de ferro, ISO 3271 de tamboramento e ISO 8731 de crepita??o. Nos testes de crepita??o avaliou-se o impacto da umidade e do tratamento t?rmico nas amostras de granulado ideal. O min?rio de mangan?s da mina de Totonho ? composto majoritariamente por Mn, Fe, SiO2 e Al2O3 com os seguintes valores 30,8%, 5,2%, 25,4% e 12,1%, respectivamente. J? para Penedo foram obtidos os respectivos valores de 25,3%, 11,7%, 21,3% e 11,1%. Os min?rios analisados apresentaram os minerais espessartita, todorokita, quartzo e dolomita em sua constitui??o mineral?gica. Outros minerais de mangan?s como pirolusita e criptomelana tamb?m foram identificados nas amostras de granulado ideal da mina de Totonho e Penedo, entretanto n?o em todas as faixas granulom?tricas. Os estudos de termogravimetria mostraram que os min?rios apresentaram perdas de massas, principalmente, associadas a elimina??o de ?gua estrutural das fases hidratadas todorokita e goethita e pela decomposi??o t?rmica dos ?xidos pirolusita e criptomelana, al?m da decomposi??o do carbonato de c?lcio e magn?sio pela dolomita. Tanto para os testes de tamboramento quanto de crepita??o, as amostras de granulado ideal mostraram alta susceptibilidade na gera??o de finos e a faixa granulom?trica de maior susceptibilidade foi em 6,3mm. A umidade aumentou de forma significativa a produ??o de finos nesta faixa durante a crepita??o para ambas as amostras. Entretanto, ap?s o tratamento t?rmico a 200? C durante 48 horas, as amostras exibiram uma redu??o de 27% no ?ndice de crepita??o para Totonho e 35% para Penedo. A redu??o dos ?ndices de crepita??o significa uma redu??o do excesso de finos e com isso uma melhor permeabilidade dos gases no forno e mais efici?ncia nas rea??es de trocas t?rmicas promovendo ganhos em rendimento t?rmico e produtivo.More than 90% of world manganese production is directed to metallurgical consumption in the manufacture of alloys. However, the level of knowledge about the geometallurgical characteristics of these ores is limited. These characteristics have important influence of the operationality of steel reactors. The present work contemplates studies of physical, chemical, mineralogical characterization and tests with metallurgical responses such as drumming and decrepitation in two manganese ore mines in S?o Jo?o Del Rei district, Totonho and Penedo. In the case of these mines, these studies are pioneering in terms of deepening the correlations of the type and quality of the ore with its metallurgical behavior on a laboratory scale. Samples from each mine were classified into global, three product types (lump ore, intermediate and fine) and in a particle size range (+19,0-6,3mm) that meets the specifications for electric ovens according to IS O8731, decrepitation. Chemical analyzes were performed by titration and atomic emission spectrometry. The mineralogical analyzes used the X-ray diffraction techniques and for ideal lump ores the optical microscopy, backscattered electron images (MEV) and dispersive energy spectroscopy (EDS) were also used. The characterization of physical properties such as density, specific surface and porosity are also presented. The metallurgical tests were adapted from the standards as references for iron ores, drumming ISO 3271 and decrepitation ISO 8731. In decrepitation tests, the impact of moisture and heat treatment on the ideal lump ore samples was evaluated. The manganese ore from the Totonho mine is mainly composed of Mn, Fe, SiO2 and Al2O3 with the following values 30.8%, 5.2%, 25.4% and 12.1%, respectively. For Penedo, the respective values of 25.3%, 11.7%, 21.3% and 11.1% were obtained. The ores analyzed showed the minerals spessartite, todorokite, quartz and dolomite in their mineralogical composition. Other manganese minerals such as pyrolusite and cryptomelane have also been identified in the ideal granulate samples from Totonho and Penedo, however not in all granulometric ranges. Thermogravimetry studies have shown that ores have mass losses, mainly associated with structural water elimination of hydrated minerals like todorokite and goethite and thermal decomposition of pyrolusite and cryptomelane oxides, as well as decomposition of calcium carbonate and magnesium by dolomite. For the drumming and decrepitation tests, the ideal lump ore samples showed high susceptibility in fines generation and the highest susceptibility particle range was 6,3mm. Moisture significantly increased fines production in this range during decrepitation for both samples. However, after heat treatment at 200 ? C for 48 hours, the samples exhibited a 27% reduction in decrepitation index for Totonho and 35% for Penedo. The reduction in decrepitation rates means a reduction in excess of fines and thus a better permeability of the gases in the oven and more efficiency in the reactions of thermal exchanges promoting gains in thermal and productive yield