Zirconium Purex process

Pure terephthalic acid (PTA) production, exhaust from, 70 105—106 Pure water, in silicon semiconductor technology, 22 232 PUREX flow sheet, 70 676 Purex process, 70 789 Pure zirconium... 

Uranium stripping Dilute HNO3 solutions at 45-50°C are used to remove uranium from the TBP phase. Traces of the fission products ruthenium and zirconium are eliminated in the second and third cycles of the Purex process. Also, in the second and third cycles, neptunium and the last traces of plutonium are removed from the uranium product. 

Uetake, N. 1989. Precipitation formation of zirconium-dibutyl phosphate complex in PUREX process. /. Nucl. Sci. Technol. 23(3) 329-338. 

Separation and Purification. In the Purex process discussed here, the uranium, plutonium, and fission products are separated by solvent extraction into three different streams (Fig. 21.20). The plutonium stream goes through anion exchange (discussed later) to reduce traces of ruthenium, and the uranium stream goes through silica gel sorption to reduce traces of zirconium. The fission-product stream, which contains the fission products... 

It is of interest to note that addition of 0.001 fluoride to the extraction scrub solution did not improve the zirconium-thorium separation significantly in the scrub section. A large improvement in zirconium-uranium separation has been observed by addition of fluoride to scrub streams in the Purex process. This difference is probably due to the thorium complexing the fluoride and lowering the free fluoride to a level which is ineffective in altering zirconium distribution. 

It is used in the mining industry to recover metals such as copper and nickel. Parasite plants, based on solvent extraction, are used in the phosphate industry to recover by-product uranium from crude phosphoric acid. The uranium concentration in phosphoric acid is very low but, because of the high volume of phosphoric acid that is produced to meet agricultural needs, considerable uranium can be recovered using solvent extraction. In the nuclear industry [5], solvent extraction is used to purify uranium and plutonium [using the plutonium and uranium recovery by extraction (PUREX) process], zirconium from hafnium, and for many other applications. It is also used in environmental applications to clean soil, say, to remove polychlorinated biphenyls (PCBs), dioxins, pesticides, and other hazardous pollutants. 

Concerning the wet separation methods, the possibility to separate neptunium, the soluble part of technetium and perhaps zirconium directly during the PUREX process is being studied. 

The ZEALEX Process Researchers from KRI have shown that the zirconium salt of dibutyl phosphoric acid (ZS-HDBP) was soluble in Isopar-L in the presence of 30% TBP. This super PUREX solvent, known as ZEALEX, extracts actinides (Np-Am) together with lanthanides and other fission products, such as Ba, Cs, Fe, Mo, and Sr from nitric acid solutions. The extraction yields depend on both the molar ratio between Zr and HDBP in the 30% TBP/Isopar-L mixture and the concentration of HN03 (232). Trivalent transplutonium and lanthanide elements can be stripped together from the loaded ZEALEX solvent by a complexing solution, mixing ammonium carbonate, (NH4)2C03, and ethylenediamine-N.N.N. N -tetraacetic acid (EDTA). An optimized version of the process should allow the separation of... 

It is also of interest to note that the effect of DBP on zirconium separation from thorium in the Acid-Thorex system is different than zirconium separation from uranium in the Purex system.(Figure k) The Purex data are from reference 6 and the Acid-Thorex data are from General Atomic Company pilot plant studies. The thorium probably forms a stronger DBP complex than does uranyl ion and, therefore, the amount of uncomplexed DBP available for raising the equilibrium distribution of zirconium would be less in the Acid-Thorex process. 

A well-designed Purex plant aims for as complete recycle of solvent as possible, to minimize costs of solvent makeup and disposal. Solvent from the uranium purification section usually contains so few contaminants or degradation products that it can be reused a number of times without cleanup. On the other hand, solvent that has processed solutions containing hi activity of fission products and plutonium carries traces of these contaminants, uranium, nitric acid, dibutyl phosphate, and other radiolytic degradation products of TBP and dodecane. Uranium and plutonium should be recovered because of their value. Fission products should be removed to prevent product contamination in later cycles. Dibutyl phosphate should be removed because it forms strong complexes with tetravalent zirconium and plutonium that would impair ability of the solvent to reject zirconium and separate plutonium from uranium. 

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