Laser Ignition of Lignite Microparticles with Different Ash Content

The laser ignition of lignite microparticles (63 μm) in the form of samples with bulk density 0.5 g/cm² is investigated. The ash content is 10.1% for the initial samples and 0.5% for demineralized samples. Radiation from a pulsed neodymium laser (1064 nm, 120 μs) and a continuous diode laser (808 nm) is used for ignition. It is found that, in comparison with the initial samples, radiation of higher energy density is required for release and ignition of volatile compounds and ignition of the nonvolatile residue from demineralized samples. When using single laser doses, the mass remaining after combustion is greater for the initial samples than for the demineralized samples. That indicates catalytic action of the coal ash in sample combustion.