LABORATORY INVESTIGATION OF THE DUST EXPLOSIBILITY CHARACTERISTICS OF 3 NOVA-SCOTIA COALS

The explosion characteristics of coal dust/air and methane/coal dust/air mixtures have been determined experimentally. All tests were conducted at initial pressures of nominally 1.0 bar in a 26 l spherical explosion bomb. Run-of-mine coal from the Prince, Lingan and Phalen seams of the Cape Breton Development Corporation was used. Two size fractions of each coal were tested at dust concentrations ranging from the lean flammability limit to 1.0 kg m-3. The explosion parameters measured for each test were the maximum explosion pressure, Pmax, and the maximum rate of pressure rise, (dP/dt)max. Methane addition to the coal dust/air mixtures was found to increase both Pmax and (dP/dt)max, the effect being most significant at low dust concentrations. A reduction in mass mean diameter of the coal or an increase in the parent coal volatile content was found to have a similar effect on Pmax and (dP/dt)max. These observations are consistent with a description of coal dust flame propagation by gas-phase combustion of devolatilization products.