Three-Dimensional Evaluation of Internal Structure of Coke Made by Blending Non-coking Coal Using X-ray Computed Tomography

Abstract

Image analysis was performed on the analytical objects constructed by X-ray computed tomography images of coke with anthracite as low swelling and softening-melting coal to evaluate the pore structure three-dimensionally. The sphericity of the pores was calculated based on the volume and surface area of the pores. Tracers were inserted into all anthracite particles to distinguish coke matrices derived from anthracite from those derived from coking coal. This is the first success in identifying coke matrices derived from coking coal and those derived from other carbon source. The sphericity of pores in the surrounding area of the coke matrix derived from anthracite and the area without coke matrix derived from anthracite was extracted from the analytical object. The surrounding area of the coke matrix derived from anthracite contained more low-sphericity pores compared to the area without coke matrix derived from anthracite. This may be due to the free expansion of the coking coal in the surrounding area of the anthracite since the anthracite does not soften or expand during carbonization. The coking coal expanded excessively to fill the voids between the particles, resulting in the bubbles bursting and generating connected pores.