Effect of binder amount on the development of coal-binder interface and its relationship with the strength of the carbonized coal-binder composite

Abstract

Production of high-strength carbonized coal composites from non-caking coals only with possible application as coke is presented. A binder and a non-caking coal were mixed in different ratios and carbonized at 1000 °C to produce coal-binder composites. Two binders, one from coal origin and other from oil origin were used. Effect of coal-binder mixing ratio and base coal particle size on the fracture strength of composites was investigated. Bonding of binder with the coal particles at coal-binder interface and development of connected carbon matrix were primarily responsible for the strength of the carbonized coal composites. The trend of change in fracture strength as a function of coal-binder fraction was similar for both the binders. However, for same coal-binder mixing ratio, binder type strongly affected the maximum strength achieved. Fracture strength was found to be primarily dependent on the coal-binder mixing ratio and base coal particle size. The main finding of this study is that the irrespective of binder type, for a given base coal particle size there was only one coal-binder mixing ratio at which the maximum strength was obtained. The binder fraction at which the highest strength observed was correlated to the carbon matrix connectivity index.