Profile of CO₂, CO, and H₂ Emissions from Thermal Oxidation of Polish Coals

The self-heating phenomenon of coal leads to work safety hazards in underground mining. The quantitative analysis of gaseous products in mine atmosphere constitutes one of the detection methods of advanced coal heating. The article presents the results of tests on CO, CO₂, and H₂ emissions during simulated heating of coal in the temperature range of 323-523 K. The oxidation of 15 Polish coals of various carbon contents was performed using a flow reactor technique. A chromatography method was applied to measure the changes of oxidation products concentrations with the increase of temperature. It has been determined that all the tested gases were generated at the initial temperature. The collected data indicated that CO₂ was a major oxidation product in the entire temperature range, while the amounts of H₂ produced did not exceed 0.49% volume. At the temperature of 323 K, the ratio of CO₂/CO was in the range of 10-23 but along with the temperature increase the ratio range narrowed to 3-4. In this paper, a comparison of the physical-chemical properties of the tested coals and the emissions profile of the gases using, among others, the hierarchical clustering analysis showed that samples with higher oxygen, sulfur, and inertinite content as well as lower ash and carbon content formed larger amounts of fire gases.