Laboratory Investigation of Underground Fire Hazard Control in Coal Mines by Use of the Pyrotechnic Aerosol

To control underground fire hazards, the principle of a pyrotechnic aerosol was adopted in coal fire-extinguishing experiments. Results show that fire extinguishing efficiency of a pyrotechnic aerosol composed of 63.4% KNO3, 23.6% C2H4N4, 8% C7H6O2, and 2% C8H5KO4 is better than that of nitrogen at 0.25 MPa. The required time to fire extinction is reduced by 41.6% in a 1 m(3) control volume. TG/DTG tests support the view that the aerosol and its residues inhibit the oxidation and retards the combustion of coal. According to the EDS tests, the solid residues of the PA are mainly alkaline potassium salts such as K2CO3 and KHCO3. The FTIR results indicate that the K from the pyrotechnic aerosol will interact with the -OH in coal samples and also creates an alkaline environment inhibiting the production of -COOH. The effect on a pyrotechnic aerosol on coal fires is to produce ultra-fine and inert residue particles to extinguish the fire.