THE INTERACTIONS OF CARBONS WITH POTASSIUM

This paper describes an investigation of the interaction of a wide ran ge of carbons with potassium. In particular, the relationships between reaction temperature, potassium adsorption, carbon structural charact erisation data (macroporosity, surface area, X-ray crystallographic pa rameters, and microstrength), and size degradation are considered in d etail. For isotropic, high surface area carbons, high potassium uptake s occurred, but no size degradation was observed. Needle-coke with flo w 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 si ze degradation is probably associated with the heterogeneity and varyi ng orientation of anisotropic components in the structure and the pres ence of mineral matter. The mechanism proposed for size degradation in volves adsorption with swelling during potassium uptake occurring in n on-uniform ways, resulting in high stresses and size degradation of th e coke lumps. The stresses set up at the interface between the carbon and mineral particles may also be significant in size degradation. How ever, carbon structural changes were observed as a result of potassium uptake irrespective of the size degradation.