Ikuo Komaki

The effect of plastic addition on coal caking properties during carbonization

The recycling process of waste plastics using coke ovens is now being studied. The effect of plastic addition on coal caking property was investigated. It was revealed that thermal decomposition products of plastics interacted with bituminous coal during carbonization in coke ovens. The effect of plastic addition on coal caking property varied with types of plastics. The addition of aliphatic polymers such as polyethylene (PE), polypropylene (PP) and poly(vinyl chloride) (PVC) had only a small effect on coal caking property and coke strength and in some cases PE addition increased coke strength. On the other hand, the addition of polystyrene (PS), poly(ethylene terephthalate) (PET) and terephtalic acid (TFA) inhibited coal expansion and fusion, decreased maximum fluidity and total dilatation, and deteriorated the coke strength. These differences were discussed from the viewpoint of the interaction between thermal decomposition products of plastics and hydrogen in coal. It was suggested that the radical formed as a result of PS or PET thermal decomposition abstracted hydrogen from coal, which resulted in the decrease in coal caking property.

Small angle X-ray scattering study on change of fractal property of Witbank coal with heat treatment

Abstract Change in the surface fractal dimension ( D s ) of Witbank coal with heat treatment was studied using small angle X-ray scattering. It was found that D s changes systematically depending on the temperature and the heating rate. Especially in the pre-softening stage, D s decreased with increasing temperature. From thermogravimetric and differential scanning calorimetric analyses, we concluded that this was derived from a physical structural change in coal. It was also found that there are lower limits ( F min ) of fractal distribution of pore surface. Further, these limits change greatly at the threshold of the coal softening temperature. It is concluded that the physical structural change of coal takes place at lower temperatures than that thought so far, and that D s and F min are valuable parameters for representing the structural changes with heat treatment.

In-situ variable-temperature single-point NMR imaging study of coals

To monitor the dynamical changes in coals with temperature, an in-situ method must be used, therefore, we have applied Single-Point-Imaging and have carried out the first systematic in-situ variable-temperature NMR imaging study of coals between 25 and 500°C with our newly developed high temperature imaging probe and systems. It was found that the distribution of mobile components was very heterogeneous like the distribution of macerals at room temperature. As the temperature became higher, the mobile component started increasing but remained heterogeneous above 400°C and over this the distribution of mobile components became more homogeneous. It is clear that in-situ variable-temperature NMR imaging method is very powerful to investigate and clarify the thermal change of coal.