Direct utilization-recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 October 1979-31 December 1979
Research is focused on the development of methods for recovering minerals from power plant fly ash. Definition and refinement of steps in the high-temperature (HiChlor) gas chlorination process and in the lime-soda sinter process are emphasized. Samples of chlorinated ash residues were analyzed to determine changes in physical structure and to measure compositions of individual particles. The results show that when ash particles are fractured by heat treatment the chlorination of contained alumina and iron is more complete. The use of SiCl/sub 4/ as a chlorination agent in addition to chlorine was studied as a method to reduce the amount of silica being chlorinated. Optimum conditions for SiCl/sub 4/ partial pressure and reaction temperature reduced the percentage of silica chlorinated from 20% without SiCl/sub 4/ to about 5%, with minimal reduction in the percentage of alumina reacted. Evaluation of waste FGD sludges and FBC residues for use as lime resources in the lime-soda sinter process has begun, and further research was conducted on high-pressure desilication of sinter extraction filtrates. At optimum conditions, the concentration of dissolved silica was reduced by 60%, but this is still in excess of the silica specification for alumina used in metal production. Chemical beneficiation of magnetically separated fly ash showed that the contained silica dissolves quickly during a high-pressure alkali extraction, and that most of the contained alumina is dissolved after one-half hour. Development of a two-stage process, first dissolving the silica and then the alumina in even less time, shows promise of further reducing the size and cost of the extraction equipment required.
- Research Organization:
- Ames Lab., IA (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5699392
- Report Number(s):
- IS-4731
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010800* -- Coal
Lignite
& Peat-- Waste Management
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320305 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
AEROSOL WASTES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORINATION
FLY ASH
HALOGENATION
IRON COMPOUNDS
IRON OXIDES
MINERALS
OXIDES
OXYGEN COMPOUNDS
RECOVERY
TRANSITION ELEMENT COMPOUNDS
WASTE PRODUCT UTILIZATION
WASTES