Petrographic and Chemical Characterization of the Bonito Seam and its Beneficiation Products, South Santa Catarina Coalfield — Brazil

The Bonito seam has become recently a new exploration and exploitation target in the South Santa Catarina Coalfield, Brazil. The present study is a contribution to an understanding of the petrographical and chemical characteristics of the Bonito seam collected at three underground mine sites, followed by beneficiation tests using a density range from <1.6 to > 2.4 g/cm3. Seam Characteristics and Ash Fusibility Tests. Averaged ash yield is 58 wt.%, volatile matter content is 16 wt.%, and calorific value is 2910 cal/g. Vitrinite reflectance indicate high volatile B bituminous rank. Inertinite and vitrinite maceral groups are most abundant. Quartz, kaolinite and pyrite are the predominant minerals. The Free Swelling Index is 1. Ash Fusibility Tests indicated an initial deformation temperature at 1260 °C, and a flow temperature at 1473 °C. Beneficiation tests. In the beneficiated sample a gradual increase of ash yields with increasing density fraction occurs, whereas volatile matter, calorific values and fixed carbon decrease. Technological properties. High ash yields and low FSI values in the 1.6 and <1.6 g/cm3 density fractions, and the predominance of non-reactive components prevents the use of the Bonito seam in coke-making. The beneficiated samples showed, however, a high potential to be used in combustion.