Effect of coal mine organic aerosol on the methane/air lower explosive limit

Abstract

AbstractOrganic aerosol is formed in coal mines due to heat release and evaporation of organics from coal during the longwall operation. This frictional heating occurs when a metallic cutting bit strikes a rock. Thus formed organic aerosol can contribute significantly to the explosivity of methane/air atmosphere in coal mines. In this paper, the flammable limits for the methane–air mixtures with organic aerosol are determined. For this purpose, organic aerosol is synthesizes from the coal-tar pitch in a laboratory evaporation–nucleation flow chamber. Aerosol particles synthesized under laboratory conditions are aggregates consisting of small primary particles with the fractal-like dimension Df = 2.0 ± 0.1, which is close to Df = 2.1 ± 0.1 of coal mine aerosol. It is shown that the flammability of organic aerosol/methane mixture in air is in good agreement with the Le Chatelier additive principle. The lower ignition limit for the pure organic aerosol in air is 44 g/m3.