Removal of Mercury from the Off-Gas from Thermal Treatment of Radioactive Liquid Waste
Acidic, radioactive wastes with a high nitrate concentration, and containing mercury are currently being stored at the Idaho Nuclear Technology and Engineering Center (INTEC). In the past, these wastes were converted into a dry, granular solid by a high temperature fluidized-bed calcination process. In the future, the calcined solids may be immobilized by a vitrification process prior to disposal. It has been proposed that a vitrification facility be built to treat the acidic wastes, as well as the calcined solids. As was the case with the calcination process, NOx levels in the vitrification off-gas are expected to be high, and mercury emissions are expected to exceed the Maximum Control Technology (MACT) limits. Mitigation of mercury emissions by wet scrubbing, followed by adsorption onto activated carbon is being investigated. Scoping tests with sulfur-impregnated activated carbon, KCl-impregnated activated carbon and non-impregnated activated carbon were conducted with a test gas containing1% NO2, 28% H2O, 4% O2 and 67% N2. Average removal efficiencies for Hgo and HgCl2 were 100 ± 2.5% and 99 ± 3.6% respectively, for sulfur-impregnated carbon. The KCl-impregnated carbon removed 99 ± 4.6% HgCl2. The removal efficiency of the non-impregnated carbon was 99 ± 3.6% for HgCl2. No short-term detrimental effects due to NO2 and H2O were observed. These results indicate that, placed downstream of a wet scrubber, an activated carbon adsorption bed has the potential of reducing mercury levels sufficiently to enable compliance with the MACT limit. Long-term exposure tests, and bed size optimization studies are planned for the future.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC07-99ID-13727
- OSTI ID:
- 910900
- Report Number(s):
- INEEL/CON-00-01332; TRN: US200802%%277
- Resource Relation:
- Conference: International Conference on Incineration and Thermal Treatment Technologies,Philadelphia, PA,05/14/2001,05/18/2001
- Country of Publication:
- United States
- Language:
- English
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