Uranium process

Originally, radium was obtained from the rich pitchblende ore found in Joachimsthal, Bohemia. The carnotite sands of Colorado furnish some radium, but richer ores are found in the Republic of Zaire and the Great Lake region of Canada. Radium is present in all uranium minerals, and could be extracted, if desired, from the extensive wastes of uranium processing. Large uranium deposits are located in Ontario, New Mexico, Utah, Australia, and elsewhere. 

Manufacturers. Besides manufacturers in the United States, commercial fluorine plants are operating in Canada, France, Germany, Italy, Japan, and the United Kingdom (see Table 5). Fluorine is also produced in the Commonwealth of Independent States (former Soviet Union) however, details regarding its manufacture, production volumes, etc, are regarded as secret information. The total commercial production capacity of fluorine in the United States and Canada is estimated at over 5000 t/yr, of which 70—80% is devoted to uranium hexafluoride production. Most of the gas is used in captive uranium-processing operations. 

Most of the phosphate esters are used in the production of hydrauHc fluids (qv), plastic and elastomer additives, flame retardants (qv), oil stabilizers, pesticides (qv), and medicinal intermediates (see Surfactants). Some trialkyl phosphates, OP(OR)2, are outstanding solvents for nitrates, especially (UO2) (N02)2, and therefore are important in uranium processing (see Extraction). 

US-Environmental Protection Agency, Draft Environmental Impact Statement for Remedial Action Standards for Inactive Uranium Processing Sites (40 CFR 192), US-EPA Rep. No. EPA 520/4-80-011 (1980). 

For comparison, we have calculated the health effects for typical residential properties (4 occupants each) based on 1) the naturally occurring background radiation levels and radionuclide concentrations in four cities across the U.S. (see Table V) and 2) the EPA (CFR, 1981) guideline values (20 yR/h, 0.02 WL, 5 pCi Ra-226/g of soil) for cleanup at inactive uranium processing sites (see Table VI). 

Silver is usually found in extremely low concentrations in natural waters because of its low crustal abundance and low mobility in water (USEPA 1980). One of the highest silver concentrations recorded in freshwater (38 pg/L) occurred in the Colorado River at Loma, Colorado, downstream of an abandoned gold-copper-silver mine, an oil shale extraction plant, a gasoline and coke refinery, and a uranium processing facility (USEPA 1980). The maximum recorded value of silver in tapwater in the United States was 26 pg/L — significantly higher than finished water from the treatment plant (maximum of 5.0 pg/L) — because of the use of tin-silver solders for joining copper pipes in the home, office, or factory (USEPA 1980). 

Zirconium presents a particular problem and is a major constituent of at least one crud in a uranium processing circuit. Also, as stated earlier, zirconium will tend to hydrolyze in an HNO3-TBP circuit given the right conditions of shear and of energy input (proximity to saturation of the solvent and the type and construction of contactor, particularly in the coalescing zone). The use of Teflon plates in columns for such an extraction process definitely increased coalescence and decreased the tendency for hydrolysis and crud formation [40]. 

Abramo, J. A. Lowings, S. W. H. Uranium processing at Exxon s Highland operation. Proceedings of AIChE Symposium on Solvent Ion Exchange, Tucson, Arizona, May 1973. 

The most common isotope of protactinium is Pa (tj/2 = 3.3 x 10 years), which occurs in pitchblende in the amount of 300 mg/ton, about the same as radium. The heroic efforts of British researchers resulted in the isolation of some hundred grams of Pa from the sludge left over from uranium processing without this supply, little or nothing would... 

According to the vendor, full-scale processes have been employed to remediate depleted uranium and uranium process residues. Systems have also been designed for treatment of natural uranium-contaminated materials. Processes for the treatment of materials contaminated with multiple heavy metals have been designed and demonstrated. RIMS was unable to determine the commercial availability of this technology. 

Fig. 1. Schematic flowsheet of uranium processing (acid leach and ion exchange) operation. Numbers refer to the numbers that appear in the boxes on the flowsheet. Operations (3), (6), (9), and (11) may be done by thickening or filtration. Most often, thickeners are used, followed by filters. The pH of the leach slurry <4) is elevated to reduce its corrosive effect and to improve the ion-exchange operation on the uranium liquor subsequently separated, In tile ion exchange operation (7), resin contained in closed columns is alternately loaded with uranium and then eluted. The resin adsorbs the complex anions, such as UC fSO 4-. in which the uranium is present in the leach solution. Ammonium nitrate is nsed for elution, obtained by recycling the uranium filtrate liquor after pH adjustment. Iron adsoibed with the uranium is eluted with it. Iron separation operation (8) is needed inasmuch as the iron hydroxide slurry is heavily contaminated with calcium sulfate and coprecipitated uranium salts. Therefore, the slurry is recycled to the watering stage (3). Washed solids from 1,6). the waste barren liquor from (7), and the uranium filtrate from (11) are combined. The pH is elevated to 7.5 by adding lime slurry before the mixture is pumped to the tailings disposal area. (Rio Algom Mines Limited, Toronto)...

The affinity of a strong-base resin for various anions commonly present in uranium process solutions can be ranked as follows U07(S04)34- > U02(S04)22- > NO, > Cl- > HS04 > Fe(S04)2- > SO4-. 

Weak-base resins have been tested from time to time but have not found wide acceptance in the uranium industry, The main reason for this is that the major advantage of weak- over strong-base resins, viz. elution by neutralization, cannot be utilized in uranium processing since it is not possible for the weak-base resin to be converted to the free-base form without diuranate precipitating within the pores of the resin (unless a complexing agent such as carbonate is added to the eluate). In the presence of carbonate, uranium remains in solution as the uranyl carbonate anion, even in very alkaline solution, so is readily eluted from a weak-base resin in the free-base form. This eluate would then be treated as depicted in equations (105) and (106) for the recovery of uranium. Alternatively, weak-base resins can be eluted by ion-exchange mass action. 

Amine reagents also extract thorium from carbonate solutions and the use of a primary amine, RNH3C1, where R = C10 to Cl3 alkyl, as a 20% solution in kerosene allowed the concentrations of impurities in the extracted thorium to be reduced by factors of 33.8 for UVI, 111.4 for MoVI, 18.9 for Zrlv and 6167 for Mg11.177 The extracted thorium species was shown to be of the composition (RNH3)4Th(C03)4(H20)x. Di(tridecyl)amine has been used to extract thorium from barren uranium process liquors in the Blind River plant in Canada147 and flowsheets for the recovery of lanthanides, U03 and high-purity Th(S04)2 from the Elliot Lake area in Ontario using Primene/isodecanol have been described.178... 

Russia Uranium processing site in 8.4 (control) 25 13 21 Gongalsky (2003)... 

EPA (1983). U.S. Environmental Protection Agency. 40 CFR Part 192—Standards for remedial actions at inactive uranium processing sites, Final rule, 48 FR 590, as amended (U.S. Government Printing Office, Washington). 

Heat exchange Phthalic anhydride synthesis Uranium processing Coal combustion... 

Hydrofluoric acid is used for manufacture of fluorocarbons, including fluoropolymers, chlorofluorocarbons chemical intermediates including fluoroborates, surfactants, herbicides, and electronic chemicals aqueous hydrofluoric acid petroleum alkylation and uranium processing. 

Initial thermodynamic and experimental studies have found a new thermochemical cycle based on uranium. The operating conditions are mild and most of the steps are commercially used in the uranium processing industry. For several of the process steps, there are multiple process options. Additional analysis and experimental work is required before engineering viability (versus scientific proof of principle) can be determined with reasonably credible estimates of efficiencies and economics. 

---