Uma abordagem de ensaio de resistência mecânica de carvão vegetal
A indústria de ferro e aço corresponde a cerca de 8% das emissões globais de CO 2 . número de repetições suficiente. Desta forma, é possível prever o comportamento de um leito de carvão vegetal sob compressão. Palavras-chave: Carvão vegetal. Resistência mecânica. Anisotropia. Compressão de leito. ABSTRACT KURAUCHI, M. H. N. An approach of charcoal mechanical strength tests. 2014. 102 p. Dissertation (Master) -Metallurgical and Materials Department of the Polytechnic School of the University of
... the University of São Paulo, São Paulo, 2014. The iron-and steel industry is responsible for about 8% of the total global CO 2 emissions. Charcoal is an existing alternative to the use of coal and coke in the metallurgical industry and is used in some blast furnaces in Brazil. Although it has some advantages against coke in terms of higher reactivity and lower ash contents, charcoal has inherently low mechanical strength and high friability, imposing difficulties to its transportation, handling and use in processes. There are no standards to evaluate charcoal compression strength, and the existing methods used in other researches consist in using prepared specimens and compressing them in the direction of the fibres. As charcoal is irregular shaped, granular and anisotropic, these tests may not reveal the behaviour of a charcoal bed, as a whole, when undergoing compressive loads. This may not relate to industrial conditions, where the load on charcoal is not exclusively applied on the direction of the fibres, but is randomly applied instead. This dissertation proposes an approach to quantify the effects of applying load on randomly distributed bulk charcoal. This represents an attempt of simulating conditions similar to what is expected in the industrial practice, such as in a blast furnace, rather than analysing individual pieces of charcoal. An apparatus has been prepared consisting of a tube and a piston that is pushed by an universal test machine. The experiments consist in carrying out repeated tests of compression of controlled sized charcoal with the apparatus. A particle size distribution is obtained as a function of the applied load, which is then classified by screening and weighing. Based on that, the particle size distribution is analysed both qualitative and quantitatively by using statistical tools. By means of the friability and survivability indexes, the method generates reproducible results with a sufficient number of repeats. In this way, it is possible to predict the behaviour of charcoal bulk under compression.