The effect of metallic iron particle on coke-matrix after coke CO₂ gasification reactio

In order to prevent pulverization and fracture of metallurgical coke, control of gasification reaction part in coke lump and embrittlement behavior is important. Addition of catalyst particle is an effective and a simple method for enhancement of the CO₂ gasification reactivity. However, the effect of the catalyst particle on coke-matrix and gasification part of coke lump after gasification reaction has not been investigated. In this study, the effect of iron particles on coke-matrix state after gasification reaction is investigated experimentally. Coke-matrix vanishing is evaluated by spatial distribution of lump porosity and microscopic observation. Elastic modulus of coke-matrix is evaluated by nano-indentation method. Coke lumps with and without iron-particles (ferrous coke and formed coke, respectively) were used. These coke lumps were gasified by CO₂-containing gas. Reaction temperature was set at 1173 K. Reaction gas compositions were set at 100/0 and 50/50 in ratio of CO₂/CO. In each reaction gas composition, in ferrous coke, a decrease in the elastic modulus of coke-matrix with progress of gasification is smaller than that in formed coke and coke-matrix vanishing occurred. It is suggested that the iron particle promotes gasification reaction of coke-matrix selectively around itself (and coke-matrix in that part is rapidly vanished). It is also suggested that this reaction mechanism maintains elastic modulus of coke-matrix because of the local rapid gasification reaction around the iron particle.