Aerial and subaquatic oxidation of coal by molecular oxygen

Abstract The oxidation behaviour of three coal types towards molecular oxygen was investigated both in aerial and subaquatic conditions. The effects of time, temperature and coal grain size were studied and compared as basic parameters influencing the oxidation process. The obtained results showed that the influence of these factors can be similar both on aerial and subaquatic coal oxidation. Among the samples, subbituminous coal was primarily found to differ with respect to oxidation in aerial and subaquatic environment. A possible explanation for this is a change in its porous system when immersed in water. For aerial oxidation of the studied coal, oxygen consumption rates R O2 (40 °C, grain size 0.06–0.15 mm) in the range of 1·10 −6 to 5·10 −6 mol O 2 .(kg.s) −1 were found, which is approximately 2–4 times higher in comparison with R O2 for the subaquatic oxidation of the coal samples.