METHOD AND PLANT FOR EXTRACTING URANIUM FROM SPENT FILTERS Russian patent published in 2001 - IPC

FIELD: recovery of radioactive wastes. SUBSTANCE: holes are punched in opposite walls of spent filter casing at ends of perforated plates and uranium is leached out while filtering hot nitric acid solution by seepage through holes made in casing and through fibrous filter cloth arranged in layer-by-layer manner. Uranium concentration in nitric acid solution is brought to desired value by repeated seepage of uranyl nitrate solution keeping in mind that uranium concentration in solution is not to exceed permissible nuclear safety level. Upon leaching filter is conveyed for rinsing, uranyl nitrate is passed for extraction, and re-extracted agent is transported for further treatment. Plant implementing proposed method has box 1 for pre-conditioning filter wherefrom uranium is to be extracted, unit 3 for leaching uranium in hot nitric acid solution, and flat vessel 4 divided into two communicating flasks . Top part of box 1 accommodates pipe 20 for introducing nitric acid solution, water inlet pipe 21, and pipe 22 for returning uranyl nitrate to top part of spent filter. Tributyl phosphate extract refining unit has extractor 11 and re-extractor 12, uranyl nitrate pre-cleaning assembly 13, and solution pumping facilities 14, 15. Assembly 13 is made in the form of flat removable trap divided by means of vertical partition 25 into two communicating flasks of which one is communicating through thinned tributyl phosphate layer 28 with filter being treated and other one is provided with stainless-steel screen 29 for passing clean uranyl nitrate solution to vessel 4. EFFECT: reduced process time, consumption of chemical agents and labor, eliminated dust escape to environment, improved nuclear safety. 2 cl, 3 dwg, 1 ex