Processing of Bolu-Himmetoglu (Type I Kerogen) and Ankara-Beypazari (Type II Kerogen) oil shales by flotation techniques were investigated for achieving clean solid fuel substitutes. Materials characterization was done through mineralogical, XRD and FTIR analyses. Flotation responses of the samples were tested with non-ionizing and ionizing collectors of cationic and anionic types. The effects of the collector dosage and pulp pH on cleaning were determined. Other important flotation parameters, conditioning time, flotation time, pulp density, particle size and frother dosage were encountered using a statistical approach, through a full two level factorial experimental design. An advanced flotation procedure, assisted by ultrasonic application, was developed for further improvement in flotation performance. The effects of cleaning on thermal characterstics and combustion kinetics were evaluated with Differential Scanning Calorimetry and ASTM methods while the changes in the emission profiles were assessed using Effluent Gas Analysis.
Himmetoglu sample was characterized as a carbonate and organic rich humic oil shale with XRD and FTIR analyses while Beypazari oil shale involved significant carbonate and clay minerals and exhibited a fulvic character with a poor organics content. Reverse flotation with amine acetates provided the most effective means of cleaning with Himmetoglu oil shale. Ash was decreased from 34.76 % to 23.52 % with a combustible recovery of 83.57 % using 800 g/ton Flotigam CA at natural pH and the calorific value increased from 4312 kcal/kg to 5010 kcal/kg. Direct flotation with amines was most effective for Beypazari oil shale cleaning. Using Armoflote 17, ash was reduced from 69.88 % to 53.10 % with 58.64 % combustible recovery using 800 g/ton Armoflote 17 at natural pulp pH and the calorific value of the sample increased from 876 kcal/kg to 2046 kcal/kg. Following optimization, ash of Himmetoglu oil shale decreased to 16.81 % with 84.10 % combustible recovery and calorific value increased to 5564 kcal/kg. For Beypazari oil shale ash decreased to % 48.42 with 59.17 % combustible recovery and the calorific value increased to 2364 kcal/kg. Ultrasonic pre-treatment before flotation further decreased the ash of Himmetoglu sample to 11.82 % with 82.66 % combustible recovery at 15 minutes pre-conditioning time and 50 % power level. For Beypazari oil shale, ash decreased to 34.76 % with 64.78 % combustible recovery after 15 minutes pre-treatment time at 70 % power level. Comparative XRD spectra and SEM analyses revealed that the extent of mineral matter removal relied on the flotation performance.
The thermal indicators considerably improved after cleaning and the extent of improvement increased with a decrease in the ash of the concentrates. Kinetic analysis showed the favorable effect of inorganics removal on the effectiveness and easiness of combustion and activation energies decreased after cleaning for both oil shales. The contributions of cleaning on the effectiveness of combustion were also revealed by the increases in the emission rates and total CO2 and CO emission amounts. CO2 emissions due to mineral matter decomposition and harmful SO2 emissions apparently decreased as a consequence of the cleaning of the undesired inorganic contituents and potentially cleaning components. Results of the cleaning and thermal analysis sudies revealed that it was possible to achieve a clean energy source alternative from oil shales through flotation and a significant potential can be anticipated for future use of oil shales as a cost effective and environmental friendly solid fuel substitute in view of Turkey& / #8217 / s great oil shale reserves.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/2/12606990/index.pdf |
| Date | 01 January 2006 |
| Creators | Altun, Naci Emre |
| Contributors | Hicyilmaz, Cahit |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for METU campus |
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