Redução do teor de cinzas dos finos de carvão vegetal por concentração gravítica a seco

Abstract

The ashes, or more especifically the impurities, of charcoal are harmful to the production of pig iron, causing higher charcoal consumption, larger slag volume and increased costs. The elimination or minimization of the ashes content is imperative. The reduction of impurities was performed based on the differential properties identified from the technological characterization of the charcoal fines. The selected options werescreening and the use of the pneumatic classifier developed by V&M Brasil and EEUFMG. The results indicated that the performance of screening (34% of impurities reduction with 27% charcoal loss) was inferior to that of the pneumatic classifier. Screening is a low flexibiltiy process based only on the particle size as separation criterion, despite being simple and widely adopted in plant practice. The pneumaticclassifier operation is based on the differences of density, size and shape of the particles submitted to an upward flow of air (dry gravity separation). This apparatus yielded enhanced results regarding impurities removal (38%) and, especially, concerning charcoal loss (10%). Due to its characteristics, it may be considered a more dynamic and versatile process. Enhanced performance was achieved by a process combining both techniques, leading to the removal of 41% of the impurities with charcoal loss as low as 5%.