THE INTERACTIONS OF CARBONS WITH POTASSIUM

This paper describes an investigation of the interaction of a wide range of carbons with potassium. In particular, the relationships between reaction temperature, potassium adsorption, carbon structural characterisation data (macroporosity, surface area, X-ray crystallographic parameters, and microstrength), and size degradation are considered in detail. For isotropic, high surface area carbons, high potassium uptakes occurred, but no size degradation was observed. Needle-coke with flow domain optical texture and low surface area had comparatively little size degradation and potassium uptake. For anisotropic metallurgical cokes with a range of types of optical textures and low surface area, significant size degradation was observed. The results suggest that size degradation is probably associated with the heterogeneity and varying orientation of anisotropic components in the structure and the presence of mineral matter. The mechanism proposed for size degradation involves adsorption with swelling during potassium uptake occurring in non-uniform ways, resulting in high stresses and size degradation of the coke lumps. The stresses set up at the interface between the carbon and mineral particles may also be significant in size degradation. However, carbon structural changes were observed as a result of potassium uptake irrespective of the size degradation.