Investigating Properties of Hard Coal Spontaneous Ignition

The study provides the analysis of the hard coal consumption in the leading economies and coal production by categories in the Russian Federation in recent years. Risks of accidents during coal transportation have been shown: its oxidation, generation of thermal energy during its auto-heating, and the emission of combustible gas, i.e., methane, causing spontaneous ignition of hard coals and an explosion, which is the basic flaw in terms of their fire and explosion hazardous properties. The analysis of literary sources has helped to determine that «fatty» coals with more developed pores to absorb oxygen are most exposed to spontaneous ignition, whereas «low-caking» coals, on the opposite, are more resistant to spontaneous ignition. Samples of crashed «fatty» hard coal in containers of К-15, К-30, and К-50 dimension-type have been studied in the assembled spontaneous ignition parameter identification unit. During one experiment, 6–8 headings in different containers were carried out until the spontaneous ignition occurred at various ambient temperatures. As a result of measuring the rates of cooling and heating of crashed hard coal samples to be studied with thermocouples, further processing of experimental data based on the thermal spontaneous ignition theory using formulas of Arrhenius, Newton, and the improved methodology of Prof. Kiselev Ya. S. with the application of the least square method, the dependence of the difference of temperatures between the environment and the sample center on time has been obtained; the main kinetic parameters have been determined, i.e., activation energy and pre-exponential coefficient. The analysis of spontaneous ignition of «fatty» and «low-caking» coals depending on their shape and accumulation dimensions has been conducted. The studies have shown that in the same conditions, a cubic shape is safer; therefore, the transportation of hard coal is safer with bulk ships with cubic-shaped cargo holds.