Uranium extraction plant

The first definite concept of a uranium extraction plant based on a fluidized bed was suggested in Germany 106>159), A key role in. this concept is played by the sorption module shown in Fig. 12. 

One manifestation of the arsenazo-III method was deployed for the determination of the uranium concentration in various process streams in a uranium extraction plant in India (Murty et al. 1997). The uranyl-arsenazo-III complex in 4 M HCl was used for determining low uranium concentrations while the complex in dilute phosphoric acid was used for high concentrations. 

Murty, B.N., Jagannath, Y.V.S., Yadav, R.B. et al. (1997). Spectrophotometric determination of uranium in process streams of a uranium extraction plant, Talanta 44, 283-295. 

Beginning in approximately 1975, both IMG and Ereeport Minerals operated large uranium recovery plants in the United States using this technology. Several plants continue to mn but a number have been closed because of the depressed uranium prices that resulted when uranium from the former Soviet Union flooded Western markets. A relatively small plant is operated by Prayon in Belgium (40). TOPO is available from Cytec Industries Inc. as CYANEX 921 extractant. D2EHPA is available from Albright Wilson Ltd. and is also sold by Daihachi as DP-8R. 

Refining to a High Purity Product. The normal yeUowcake product of uranium milling operations is not generaUy pure enough for use ia most nuclear appHcations. Many additional methods have been used to refine the yeUowcake iato a product of sufficient purity for use ia the nuclear iadustry. The two most common methods for refining uranium to a high purity product are tributyl phosphate (TBP) extraction from HNO solutions, or distiUation of UF, siace this is the feedstock for uranium enrichment plants. 

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). 

The solvent extraction process that uses TBP solutions to recover plutonium and uranium from irradiated nuclear fuels is called Purex (plutonium uranium extraction). The Purex process provides recovery of more than 99% of both uranium and plutonium with excellent decontamination of both elements from fission products. The Purex process is used worldwide to reprocess spent reactor fuel. During the last several decades, many variations of the Purex process have been developed and demonstrated on a plant scale. 

There are two useful side products. The H2Sip6 is shipped as a 20-25 % aqueous solution for fluoridation of drinking water. Fluorosilicate salts find use in ceramics, pesticides, wood preservatives, and concrete hardeners. Uranium, which occurs in many phosphate rocks in the range of 0.005-0.03% of UsOg, can be extracted from the dilute phosphoric acid after the filtration step, but this is not a primary source of the radioactive substance. The extraction plants are expensive and can only be justified when uranium prices are high. 

By calcnlating the residence times of the various solids in the tank and relating them to their corresponding extraction curves, the total uranium extraction for the entire train of mixers was estimated. The cost of the various mixer options, the prodnction efficiency net resnlt, and the cost of the installation and tank design conld be combined to yield the economic optimum for the plant. 

Spray column contactors were used in the first large-scale solvent extraction plants at Hanford, Washington, for recovering plutonium from irradiated natural uranium and in the first chemical processing plant at Idaho for recovering enriched [L2]. 

The great improvement in performance of pulse columns over other column-type contactors, and the simple and reliable equipment involved, have led to the widespread use of pulse columns in many solvent extraction operations separating and purifying nuclear materials. In addition to their use in some fuel reprocessing operations, as mentioned above, pulse columns have been used in uranium purification plants at Femald, Ohio [Cl], and Gore, Oklahoma (cf. Chap. 5). 

Amine extraction in the Kerr-McGee mill. As a practical example of the use of organic amines to extract uranium from leach liquors, a description will be given of the solvent extraction section of the Kerr-McGee uranium mill, whose leaching section was described in Sec. 8.5 of this chapter [M3, H4]. The solvent extraction plant consists of two similar circuits process conditions approximating those of one circuit are shown in Fig. 5.9. 

The feed to the solvent-extraction plant may be characterized as plutonium and uranium nitrates and fission product nitrates. Although the latter comprise some 70 elements, there are only a few that partially extract into the TBP/OK solvent, and of these, Zr, Nb, and Ru are the most important. Of the transuranic elements, Np is the only one to extract with the plutonium and uranium to any significant degree. 

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