EFFECT OF HYDROTHERMAL TREATMENT ON CAKING PROPENSITY OF COAL

The development of caking propensity in a non-caking coal under hydrot hermal conditions has been studied, using water up to 400 degrees C un der autogenous pressure. Although it was not possible to obtain unifor m development of caking propensity or to isolate a product with upgrad ed caking capacity without in situ agglomeration, hydrothermal treatme nt promoted the formation of a coke-like mass. The role of water near its critical temperature in incipient hydrogenation was observed. Comp arison with the normal coalification track provided apparent reasons f or the observed limited development of caking propensity in the coal u sed. The overall effect appears to be the resultant of deoxygenation o r dehydroxylation, hydrogenation and polymerization reactions that may be coal-specific.