DISPOSAL OF RADIOACTIVE WASTE IN THE VITRO-TYPE URANIUM MILLING FLOWSHEET

Technical Report · Sun Oct 01 00:00:00 EDT 1961

OSTI ID:4827756

Tame, K E; Valdez, E G; Rosenbaum, J B

Pollution from radioactive nuclides, principally Ra/sup 226/, in liquid waste from uranium mills can be minimized by reusing the waste solution within the mill. Such reuse of waste solution in an acid leaching process for dissolution of the uranium, countercurrent decantation for liquid-solid separation and washing, and amine solvent extraction for recovery of the uranium from solution was investigated. The simulated reuse of barren raffinate in the mill circuit was carried through two separate laboratory campaigns of 29 and 31 cycles. Conventional chloride stripping of the amine was employed in the first campaign, whereas nitrate stripping was used in the second campaign. Dissolution of uranium from the ore in the acid leaching circuit averaged 96%. Washing efficiencies of 98 to 99% were attained by using 4 volume tons of combined raffinate and makeup water per ton of ore. Uranium recovery from the pregnant solution using a 5% solution of amine LA-1 in kerosene ranged from 99.3 to 99.9%. In the first campaign, the loaded organic was stripped with a 1.5 molar sodium chloride solution acidified to pH 1.0 with sulfuric acid. Recycle of organic in the chloride form and the reuse of barren raffinate in the washing circuit combined to cause a buildup of chlorides in the pregnani solution, which adversely affected uranium extraction by the amine. Control of the chloride level was attained by use of a soda ash scrub on a portion of the stripped organic. Uranium recovery was 99.9% when 42% of the organic flow was scrubbed, whereas the extraction dropped to 99.6% when only 17% of the organic was scrubbed. Molybdenum, which is coextracted with the uranium, also was purged by use of the soda ash scrub. Use of ammonium nitrate as an alternative to sodium chloride for stripping was investigated. The stripped organic was scrubbed with ammonium hydroxide solution to remove nitrates, and the scrub liquor subsequently acidified with nitric acid for use in stripping uranium from loaded amine. No marked advantage for either stripping system was apparent. The radioactivity in the pregnant solution and raffinate ranged from 300 to 800 disintegrations per minute (d.p.m.) of Ra/sup 226/ per liter, which appeared to be the saturation limit, and did not increase upon continued recycle of the raffinate. Reuse of waste solutions in the mill circuit appears feasinle for attaining a 75% reduction in the discard of dissolved radionuclides. (auth)

• Research Organization: Bureau of Mines. Salt Lake City Metallurgical Research Center
• NSA Number: NSA-16-021859
• OSTI ID: 4827756
• Report Number(s): BM-RI-6011
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

WASTE DISPOSAL AND PROCESSING
AMINES
AMMONIUM COMPOUNDS
CHLORIDES
COUNTER CURRENT
DISTILLATION
HYDROXIDES
LEACHING
MOLYBDENUM
NITRATES
NITRIC ACID
PETROLEUM
RADIUM 226
RECOVERY
SODIUM CARBONATES
SODIUM CHLORIDES
SOLUTIONS
SOLVENT EXTRACTION
SULFURIC ACID
URANIUM
WASTE DISPOSAL
WASTE PROCESSING
WASTE SOLUTIONS