Recovery of alumina from fly ash: use of coal cleaning refuse as a mineralizer in the lime-sinter process
The efficiency of alumina recovery from coal fly ash by the lime-sinter process is improved by the addition of a small amount of coal cleaning refuse. Approximately 5.0 wt % refuse increases alumina recovery from 55% to 90% for subbituminous coal ashes and reduces the required sintering temperature from 1380 to 1200/sup 0/C. Mixtures of fly ash and various amounts of coal cleaning refuse and limestone are sintered at different temperatures and lengths of time to determine the optimum processing conditions. X-ray diffraction analysis is used to obtain qualitative and quantitative information about the alumina compounds formed during sintering and to relate their formation to the amount of alumina recovered from the fly ash. Alumina compounds identified in the sintered mixtures are: calcium alumina ferrite (C/sub 4/AF), calcium aluminate (C/sub 12/A/sub 7/), calcium sulfoaluminate (C/sub 4/A/sub 3/S), and gehlenite (C/sub 2/AS). The C/sub 4/A/sub 3/S and C/sub 12/A/sub 7/ are soluble and account for 90 to 95% of the recovered alumina. The C/sub 4/AF and C/sub 2/AS are insoluble and remain in the solid residue. Other calcium aluminates such as CA or C/sub 3/A may form during sintering, but not in large enough quantities (less than 1 wt %) to be identified in the x-ray patterns obtained. The results of this work will be used for the further development and commercialization of the lime-sinter process for the recovery of alumina from coal fly ash. 11 references, 8 figures.
- Research Organization:
- Ames Lab., IA (USA); Iowa State Univ. of Science and Technology, Ames (USA). Dept. of Chemical Engineering
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6821036
- Report Number(s):
- IS-M-478; CONF-831244-2; ON: DE84012840
- 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
320302 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Materials
ADDITIVES
AEROSOL WASTES
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ASHES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
COAL
COAL PREPARATION PLANTS
ENERGY SOURCES
FABRICATION
FLY ASH
FOSSIL FUELS
FOSSIL-FUEL POWER PLANTS
FUELS
INDUSTRIAL PLANTS
MANAGEMENT
MATERIALS
MATERIALS RECOVERY
MINERALIZATION
OXIDES
OXYGEN COMPOUNDS
POWER PLANTS
PROCESSING
RECOVERY
RESIDUES
SINTERING
THERMAL POWER PLANTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES