Article ID: 040105
Brown coal has high moisture and volatile contents, and a low heating value per unit weight. In order to use the brown coal as a substitution fuel for bituminous coal, it needs to be dried and carbonized to upgrade the heating value to be similar to that of bituminous coal. In this upgrading process, it is necessary to consider the combustion efficiency and retain a certain amount of volatile matter. However, the upgraded coal containing volatile matter has a high risk of spontaneous combustion, making the long-distance transportation and long-term storage difficult. Therefore, this study examined a facile method to inhibit the spontaneous combustion of the upgraded brown coal by stabilizing the aliphatic hydrocarbons. Quantum chemical calculations revealed that carboxyl and ester groups generated during the oxidation process of upgraded coal's methyl groups are chemically more stable. Based on the calculation results, Loy Yang coal, a representative brown coal from Victoria, Australia, was upgraded at 430°C, and the oxidative behaviors of the upgraded coal were experimentally verified using FT-IR, NMR, TG/DTA, and GC-TCD. As a result, it was confirmed that the oxidation of the upgraded coal at 240°C can reduce the degree of spontaneous combustion while maintaining the yield of the oxidation treatment.
