LASER PYROLYSIS OF COAL

A laser pyrolysis study was performed on No. 6 high volatile bituminous Illinois (USA) coal. Possible relationships between the elemental surface composition of solid samples and the variable output power and wavelength of the argon ion laser were observed. For wavelengths of 5017 Å and 5145 Å and incident powers of 0·24 and 0·54 watts, scanning electron microscopy coupled with X-ray energy spectral analysis indicated the highest content reduction in both organic and mineral sulfur. Mass spectroscopy was employed to analyze the composition of the evolved gases from laser pyrolysis of pulverized coal. Coal pyrolysis utilizing a 2·5 watt argon ion laser produced hydrogen sulfide through decomposition of pyritic sulfur FeS2, or organic sulfur upon irradiation of the coal. Other gases such as methane and ethane were created with solid residues (tars and ash). Pulsed CO2 laser irradiation of coal samples produced a solid residue having a different elemental composition than that of the original coal sample. © 1990.