Aluminum hydroxide dissolution in synthetic sludges
In the revised Stage 1 Defense Waste Processing Facility, aluminum hydroxide dissolving has been moved from S Canyon to the waste tank farm. The maximum attainable temperature has been reduced from 107/sup 0/C in the stainless steel dissolver to less than 90/sup 0/C in the large mild steel waste tanks. Also, caustic strength must be maintained below 6.5 molar to avoid caustic cracking. Studies at TNX indicate that 75% of the crystalline aluminum hydroxide can be dissolved while using about one-third of the caustic quantity specified for the S Canyon dissolver. Studies were made in laboratory-scale and large-scale equipment to determine optimum conditions for dissolving the most aluminum hydroxide with the least caustic. These studies showed that gibbsite Al(OH)/sub 3/ is readily dissolved at low caustic strength, low addition rate, and at easily attainable in-tank temperatures. On the other hand, most of the boehmite AlOOH can be dissolved, but a lengthy digestion period is required at maximum temperatures and caustic strengths. Fortunately, 72% of the total aluminum hydroxide in the waste sludge is gibbsite and 28% is boehmite according to recent sludge analyses. Recommendations are made for the in-tank conditions needed to dissolve 75% of the aluminum hydroxide contacted. With low boehmite sludges, mild dissolving conditions are adequate while providing good caustic economy. With higher boehmite sludges, the harsher conditions within existing constraints are recommended.
- Research Organization:
- Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.
- DOE Contract Number:
- AC09-76SR00001
- OSTI ID:
- 5363468
- Report Number(s):
- DP-1617; ON: DE82009924
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM HYDROXIDES
CONTAINERS
DISSOLUTION
HYDROGEN COMPOUNDS
HYDROXIDES
MANAGEMENT
NATIONAL ORGANIZATIONS
OPTIMIZATION
OXYGEN COMPOUNDS
PROCESSING
RADIOACTIVE WASTE PROCESSING
REMOVAL
SAVANNAH RIVER PLANT
SLUDGES
SODIUM COMPOUNDS
SODIUM HYDROXIDES
TANKS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
WASTE MANAGEMENT
WASTE PROCESSING