Laser-induced macrofluorescence of coal: oxidation and macroalteration

Surface Properties of Photo-Oxidized Bituminous Coals: Final report

“…Therefore, Luminescence Intensity @ 600 nm although alteration patterns represent a good guide to the differences in photo-oxidation experienced by different vitrains, they appear to be less useful for expressing the relative quality of the hydrophobicity of the surface. This is contrary to observations made on naturally weathered coals (vitrains) where the initial luminescence intensity is generally much lower than that of the fresh surface and the alteration patterns are only positive (3,4,5,17).…”

“…In this regard, Death et al (16,17) used a HeCd laser operating at 325 and 442 nm to demonstrate that luminescence emission intensity from pressed or powdered coal surfaces decreased with degree of thermal and chemical oxidation. Except for some difficulty in maintaining stability of their photomultiplier, they suggested that the method might be suitable for on-line discrimination of oxidized coal using run-of-mine particles.…”