Removal of mercury from solids using the potassium iodide/iodine leaching process

摘要

Potassium iodide (KI) and iodine (I(sub 2)) leaching solutions have been evaluated for use in a process for removing mercury from contaminated mixed waste solids. Most of the experimental work was completed using surrogate waste. During the last quarter of fiscal year 1995, this process was evaluated using an actual mixed waste (storm sewer sediment from the Oak Ridge Y-12 Site) . The mercury content of the storm sewer sediment was measured and determined to be approximately 35,000 mg/kg. A solution consisting of 0.2 M I(sub 2) and 0.4 M KI proved to be the most effective leachant used in the experiments when applied for 2 to 4 h at ambient temperature. Over 98% of the mercury was removed from the storm sewer sediment using this solution. Iodine recovery and recycle of the leaching agent were also accomplished successfully. Mathematical model was used to predict the amount of secondary waste in the process. Both surrogate waste and actual waste were used to study the fate of radionuclides (uranium) in the leaching process.