We have recently presented a novel method which can not only dewater but upgrade low rank coals under mild conditions. This method consists of treatment of coals in non-polar solvents, such as 1-methylnaphthalene, at temperatures below 350℃. One of the remaining problems to be solved for this method is whether it can suppress self-ignition of low rank coals. In this study, self-ignition tendencies were examined for the samples prepared from an Australian brown coal by the proposed method. It was found that the treated coal obtained from this method contained little water and had the heating value corresponding to high rank coal. The self-ignition tendency of the extracted fractions was remarkably suppressed due to their small pore surface area which minimizes oxygen access to them. The self-ignition tendency of the solvent treated coal was smaller than the pyrolyzed coal, which was caused by the coating of the extracted fractions. However, the self-ignition tendency of the solvent treated coal was still slightly higher than that of raw coal.
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