Optical properties of carbonized preoxidized vitrinites

✍ Scribed by Fariborz Goodarzi; Duncan G. Murchison

• Publisher: Elsevier Science
• Year: 1973
• Tongue: English
• Weight: 492 KB
• Volume: 52
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(73)90072-0

✦ Synopsis

The optical properties at 546 nm of three vitrinites (daf carbon contents 82.5, 88.0 and 93.1%) have been examined after pre-oxidation for 14 days at 105°C and carbonization at intervals of 50°C within the temperature range 300-800°C.

In general, pre-oxidation prior to carbonization produces only relatively small changes in the trends of optical parameters with temperature that were observed for the same vitrinites when carbonized fresh; the properties of the anthracitic vitrinite displayed little modification. Reflectivities of carbonized pre-oxidized vitrinites of bituminous rank are higher than those for the equivalent fresh vitrinites up to 5OO"C, supporting the suggestion that oxidation raises aromaticity and consequently the reflectivity.

The most noticeable optical difference occurs with the bituminous-rank vitrinites, in the variation with carbonization temperature of their refractive-index curves, which parallel the behaviour of the L, curves of Xray diffraction studies. In particular, the refractive-index track for the carbonized preoxidized vitrinite of coking-coal rank no longer shows the same marked contrast to the refractive-index tracks of vitrinites of higher and lower rank, as it does at temperatures above 600°C when carbonized fresh. The absorptive indices follow similar trends to the reflectivities for all the chars.