Estudo para determinação da periodicidade de limpeza dos filtros de mangas na etapa de processamento do carboneto de silício

Abstract

The objective of this study is to determine the cleaning frequency of bag filters used in the silicon carbide (SiC) processing stage. The procedures were outlined through the following analyses: particle size, loose density, chemistry (titrations, loss by acid treatment and dry combustion to determine the SiC content and impurities such as Fe2O3, Al2O3, Cfree, Si and SiO2) and scanning electron microscopy (SEM) . The results demonstrated that there is a direct relationship between the particle size and the loose density of the SiC powder collected in the filter hopper and the accumulation of material retained therein, thus making it possible to establish a system for cleaning the filters. In other words, the indication for cleaning is the presence of materia l captured in the finer and less dense hopper. Regarding the other tests performed, the following were observed: the predominance of particles smaller than 20 µm in the images obtained in the SEM; the percentage of SiC, Sifree, Fe2O3 and Al2O3 did not reach a relationship between the particle size and the different stages of blowing, and SiO2 and Cfree decreased at the time of blowing. Industries that emit particulate matter in their manufacturing process must comply with the maximum emission limit under penalty of losing their environmental license, therefore the good functionality of bag filters throu gh a maintenance and cleaning schedule is one of the essential measures to comply with the requirements of the environmental agency.