Surface properties of photo-oxidized bituminous coals. Technical progress report for the period July--September 1996
During this report period, irradiation (photo-oxidation) of all six vitrain concentrates for three different time periods (10, 50 and 100 min) using the BLAK-RAY ultraviolet lamp was completed along with film flotation and surface luminescence measurements for each condition. Flotation results from photo-oxidized powdered vitrains appear to be contrary to earlier results obtained from contact angle measurements on polished surfaces. Some of the more strongly photo-oxidized powders, particularly for hvAb and mvb coals, exhibit greater hydrophobicity. The changes in hydrophobicity as well as a measured decrease in surface luminescence with increasing irradiation time, clearly shows that UV irradiation has had an influence on surface properties. There is some possibility that increasing exposure to the UV source may cause mobilization of aliphatic compounds (oils) from the fresh fracture surfaces of vitrain. These compounds, once exuded onto the surface could act like a natural flotation collector that would both increase particle hydrophobicity and may obscure the surface from further oxidation. Because most aliphatic compounds do not luminesce, their presence on the surface would reduce measured luminescence. A second possible explanation is that the types of oxygen functional groups which form during UV irradiation may inhibit or promote hydrophobicity depending upon their concentration. In an attempt to resolve these issues several analytical tests will be undertaken. Pyrolysis GC/MS will be used to investigate whether photo-oxidation of bulk vitrains was sufficiently severe with increasing UV irradiation. Reflectance-mode FTIR will be used to measure changes in surface chemistry for some of the irradiated powdered vitrains.
- Research Organization:
- Pennsylvania State Univ., Coal and Organic Petrology Labs., University Park, PA (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Fossil Energy, Washington, DC (United States)
- DOE Contract Number:
- FG22-93PC93223
- OSTI ID:
- 650119
- Report Number(s):
- DOE/PC/93223-T12; ON: DE98050575; TRN: AHC2DT04%%30
- Resource Relation:
- Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
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