INFLUENCE OF PITCH ADDITIONS ON COAL CARBONIZATION - COKE STRENGTH AND STRUCTURAL-PROPERTIES

The influence of pitch addition to charges of single low-rank caking coals and to a blend of low- and high-rank coals was investigated using a small oven capable of producing dense, high-strength coke in amounts sufficient to permit measurements of strength and structural parameters. For the single-coal charges, changes in the carbon textural index induced by pitching addition were associated with corresponding changes in the coke microstrength. However, addition of any of the pitches studied resulted in reduced coke tensile strength. The blended charge gave a low-porosity coke with low strength, implying that the coals were incompatible, lacking mutual fusibility. pitch addition resulted in increased textural index and microstrength and reduced porosity but only small changes in tensile strength. For these charges it is considered that enhanced blend fusibility offsets the adverse influence of reduced porosity on coke tensile strength.