Effect of coke breeze distribution on coke combustion rate of the quasi-particle

Coke combustion rate in an iron ore sintering process is one of the most important factors for quality and productivity of sintering iron ore. In order to improve coke combustion efficiency, a new granulation method was developed. In the new granulation method, coke and limestone are segregated to the particle's surface. The purpose of this study is to investigate the effect of coke distribution in the quasi-particle on coke combustion rate. Four kinds of samples, which have different coke distributions, were prepared. The samples consist of interior part and exterior part. Combustion experiments were carried out under air atmosphere at 1 073 K, 1 223 K, 1 373 K and 1 523 K. From the results, coke combustion rates were improved when added coke were segregated to sample's surface. At higher experimental temperature, the combustion rates become faster. The results were analyzed by using unreacted-core model with one reaction interface. From the kinetic analysis, it was found that the coke distribution of the quasi-particle had effects on not the interfacial reaction rate but the oxygen diffusion. In other words, oxygen diffusion in the quasi-particle become faster when added coke was segregated to the quasi-particle's surface. This is one of the main reasons that coke combustion rate in quasi-particle made from new granulation method was improved.