Sealed-flask test for evaluating the self-heating tendencies of coal. Rept. of Investigations/1990

The report describes laboratory studies by the U.S. Bureau of Mines to determine the suitability of a static oxygen (O2) adsorption test for evaluating the self-heating tendencies of coals. Reliable minimum self-heating temperature (SHT) values from adiabatic oven tests were used as standards for comparison and evaluation. A suite of six coals was tested in the adiabatic oven land in sealed flasks. In the latter tests, both undried and dried samples, in a range of four particle sizes, were examined. Miniature pressure transducers monitored pressures in the flasks, and gas samples taken at the end of the tests quantified all the gases present. An excellent correlation was found between the minimum SHT's and amounts of (O2) adsorbed over a 7-day period for dried coals, independent of particle size. In addition, a good correlation was obtained between the minimum SHT's and pressure changes in the flasks at the end of the test for the same coals, also independent of particle size. Based on these results, the sealed flask test can be reliably used to determine the self-heating tendency of a bituminous coal sample.