Degradação Mecânica Do Coque Em Testes De Tamboreamento

Abstract

ResumoEsse estudo avaliou a resistência mecânica a frio do coque, utilizando pequenas quantidades (300 a 1200 g) desse material, como alternativa aos testes usuais que utilizam 10 e 50 kg de coque. Para isso, as degradações volumétrica e superficial foram avaliadas em um tambor de menores dimensões (Diâmetro: 268 mm, comprimento: 470 mm), bem como no tambor especificado pela norma JIS K2151 (1,5 x 1,5 m). Para o equipamento menor encontrou-se que a taxa de degradação superficial (K) aumenta ligeiramente com a massa tamboreada. O fator de maior relevância foi a velocidade de rotação do tambor, que variou de 24 a 85 rpm. Nesse caso, K decresce com a velocidade. Embora a 24 rpm a taxa de degradação superficial tenha sido alta, a quebra volumétrica não ocorreu de forma relevante, sendo que essa ocorreu somente acima de 45 rpm. No tambor maior obteve-se uma maior degradação, em comparação com o tambor menor. Entretanto, há uma boa correlação entre a degradação nos dois equipamentos, possibilitando obter funções para se estimar a degradação que seria obtida no tambor maior mediante a degradação observada no tambor menor, ou seja, é possível avaliar a degradação do coque utilizando pequenas quantidades desse material. Palavras-chave: Degradação mecânica do coque; Teste de tamboreamento; Resistência mecânica a frio do coque. MECHANICAL DEGRADATION OF COKE IN DRUM TEST AbstractThis study aims to evaluate the coke's cold strength using small sample mass (300 to 1200g) in alternative to the usual tests which use 10 to 50 kg of coke . For this objective the surface and volume breakage were evaluated in a small drum (268 mm in diameter and 470 mm in length) as well as in the drum specified by the regulation JIS K2151 (1.5 m in diameter and 1.5 m in length). For the small equipment it was found that the surface breakage rate constant (K) slightly increases with the mass tumbled. The most relevant factor was the drum rotation speed that varied from 24 to 85 rpm. In this case, K decreases as speed decreases too. Although at 24 rpm this surface breakage was high, the volume breakage did not occur relevantly, and this happened only above 45 rpm. When the tumbling was conducted in a bigger drum (1.5 m x 1.5 m), it was obtained a higher degradation, comparing to the smaller drum. However, there is a close relationship between the degradation in both drums, allowing to obtain functions that correlate degradation observed in the smaller drum, that is, it is possible to evaluate the coke's degradation using small quantities of this raw material. Keywords: Mechanical coke breakage; Drum test; Coke's cold strength. INTRODUÇÃOA maior parte da produção de aço no mundo está vinculada à redução de uma carga em alto-forno (AF) a coque [1], sendo esse o insumo com maior impacto no custo do ferro gusa [2]. Fatores como a exigência de coque que atenda às demandas cada vez mais restritas do AF a partir de fontes de menor qualidade, logo mais baratas,

Estudo Da Estabilização Do Coque Metalúrgico

“…Silva (2016) [5], observed that, during transport, screening and charging of coke in the blast furnace, it exists three distinct mechanisms of fragmentation, evidenced in Figure 2. For Silva (2016) [5], even if the drum test does not accurately represent all the efforts that coke is submitted to its consumption in the blast furnace, the test must essentially reproduce the mechanisms of degradation that occurs in such fuel, considering the importance of evaluating the coke resistance to mechanical fragmentation. According to Silva (2016) [5], initially the surface degradation rate of the coke submitted to the drum is high.…”

“…For Silva (2016) [5], even if the drum test does not accurately represent all the efforts that coke is submitted to its consumption in the blast furnace, the test must essentially reproduce the mechanisms of degradation that occurs in such fuel, considering the importance of evaluating the coke resistance to mechanical fragmentation. According to Silva (2016) [5], initially the surface degradation rate of the coke submitted to the drum is high. This rate is reduced through the progression of the test.…”

“…This rate is reduced through the progression of the test. According to Ulhôa (2011) [7], the concept of mechanical stabilization is usually applied according to the volumetric fragmentation of coke, however, according to Silva (2016) [5], this concept can also be extended to surface degradation. These conclusions were also observed in this study and they were used as a basis for the analysis of the Cracking application results.…”