Low temperature polymorphic transformations of calcined alumina
The factors which affect the transformation of amorphous alumina to crystalline alumina in the temperature range 350 to 650/sup 0/C were studied. Amorphous alumina, with small amounts of added impurities, was heated in an atmosphere containing the oxides of nitrogen, air, and water vapor, and the amount of crystalline alumina was determined. Alpha alumina was the predominant crystalline form after heating amorphous alumina that was prepared in a fluid bed calciner. The effects of temperature, composition of the atmosphere, time of heating, impurities, and method of preparation of the amorphous alumina on the transformation to crystalline phases were investigated. An atmosphere containing water vapor and the oxides of nitrogen and a small amount of sodium nitrate in the alumina product were necessary to produce the alpha alumina phase from amorphous alumina at the relatively low temperature of 400/sup 0/C. Boric acid added to the fluid-bed calciner feed successfully inhibited the formation of the alpha crystalline form.
- Research Organization:
- Phillips Petroleum Co., Idaho Falls, ID (USA). Atomic Energy Div.
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- DOE Contract Number:
- AT(10-1)-205
- OSTI ID:
- 6892368
- Report Number(s):
- IDO-14581
- Country of Publication:
- United States
- Language:
- English
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ALUMINIUM OXIDES
CRYSTALLIZATION
CALCINED WASTES
PHASE TRANSFORMATIONS
RADIOACTIVE WASTE PROCESSING
SOLIDIFICATION
AIR
AMORPHOUS STATE
BORIC ACID
CALCINATION
FLUIDIZED BED
HIGH TEMPERATURE
IMPURITIES
NITROGEN OXIDES
SODIUM NITRATES
TEMPERATURE EFFECTS
WATER
WATER VAPOR
ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
FLUIDS
GASES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MANAGEMENT
MATERIALS
NITRATES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
POLLUTANTS
PROCESSING
PYROLYSIS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
SODIUM COMPOUNDS
THERMOCHEMICAL PROCESSES
VAPORS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
052001* - Nuclear Fuels- Waste Processing