Relationships between the optical reflectance of coal blends and the microscopic characteristics of their cokes

The aim of the present study was to investigate the relationships between optical properties of various coal blends and their resulting cokes. Twenty-seven various cokes were produced in laboratory scale from three Polish coals of different caking ability and from their binary and ternary blends. Mean random reflectance of the parent coals and their blends was compared to the reflectance parameters and microtexture of their produced cokes. The results show a strong positive correlation between the reflectance of the initial coal blends and the optical properties of their cokes. This relationship is stronger for cokes from the binary than from the ternary blends. It was also revealed that the degree of optical anisotropy of coke depended not only on the rank but also on the coking properties of parent coal. Close relations between the reflectance parameters of cokes and the nature of the microtexture of their binder phase were observed.This study also proposes a new method of coke classification which includes the simplified description of coke microtexture combined with the measurement of bireflectance value of its binder phase.