2013 Volume 53 Issue 7 Pages 1165-1171
The effect of iron oxide on coals and Hyper-coal (HPC) during caking temperature was investigated. To reveal the effect of the iron oxide reduction reaction on the thermoplastic properties, iron oxide reduction ratios were calculated from titration and gas analysis, and the thermoplastic properties of coal or HPC with and without iron oxide were estimated using thermogravimetric analysis and the Gieseler test. In addition, to investigate the mechanism of the change in the thermoplastic properties of HPC, the reduction ratios calculated from the titration and gas analysis were compared, and the crystal structure of HPC was analyzed using transmission electron microscopy (TEM). As a result, the iron oxide reduction reaction took place in the thermoplastic range, and the weight loss of samples with iron oxide addition increased while the fluidity decreased. On the basis of gas analysis, it was found that the reduction ratio was mainly composed of oxygen derived from H2O vapor. This result suggested that hydrogen atoms generated from the thermoplastic components of the HPC were involved in the reduction reaction. Thus, the polymerization rate of HPC was promoted near iron particles in the thermoplastic range, and the crystal structure of HPC with iron oxide addition was different between near and far from the iron particles. We, therefore, revealed that the reduction reaction by hydrogen atoms from HPC occurred in the thermoplastic range, and that the polymerization rate of HPC with iron oxide addition was increased due to decomposition of the thermoplastic components of the HPC.