Influência de diferentes intervalos de tempo e temperatura de queima nas propriedades mecânicas de pelotas obtidas de resíduos de minério de manganês.

Due to the increasing scarcity of rich ores in the metals of interest and the generation of tailings with fine granulometry, the pelletizing has been presented as the most appropriate current process for the use of these materials. This work aimed to study the influence of different times and temperatures of burning on the pelletizing of manganese ore tailings. At the first time, a sample of the ore was ground and sifted until a desired particle size of 0.044mm. Thereafter, mixtures were made with 12% activated carbon, 9% and 12% calcium oxide. Pellets were obtained with addition of water and the burnings occurred under four working conditions: 1155°C for 10min, 1155°C for 30min, 1160°C for 10min and 1160°C for 30min. The products were characterized by OM, SEM/EDS, X-ray diffraction, image analysis, mass loss, geometric density and compressive strenght tests. All samples, regardless of the working condition, presented high porosity, typical of burned pellets. In the SEM/EDS analyzes, phases with predominance of manganese and silicon were detected, evidencing the presence of quartz. The X-ray diffraction detected the phases: bixbyite, jadeite, magnesioferrite, bustamite, aegirin, diopside and braunite. The highest porosity, (34.44 ± 6.48)%, was found for the working condition with 12% CaO, burning at 1160°C for 30min. In general, the mass loss of all working conditions remained close to 30%. The work condition with the largest mass loss, (35.5 ± 0.03)%, was for 9% CaO, burning at 1160oC for 10min. The geometric density values of the pellets were low. For the pellets with 9% calcium oxide these values were close to (1.20 ± 0.14)g/cm³ and for samples with 12% calcium oxide, approximately (1.05 ± 0.14)g/cm³. The highest mechanical strength was of (0.4338 ± 0.3)kN for the working condition with 12% CaO, burning at 1160°C for 30min.