Solvent Extraction and Separation of Hafnium from Zirconium with DIBK
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Solvent extraction and separation between zirconium and hafnium under acid medium were carried out with diisobutyl ketone(DIBK) as extractant and TBP or P204 as additive.The effects of acid medium,TBP addition,P204 addition and salting-out agent(NH4)2SO4 addition on the extraction and separation of hafnium from zirconium were investigated,respectively.The results show that DIBK selectively extracts the hafnium only in HSCN medium,and the extraction rate of hafnium and separation factor of hafnium and zirconium can significantly be improved when TBP or P204 is added.The separation factor of hafnium from zirconium is 9,and the extraction and separation of zirconium and hafnium with DIBK is similar to the performance of MIBK.Keywords:
Hafnium
Methyl isobutyl ketone
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Hafnium
Hydrochloric acid
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The authors' company developed a new solvent extraction process for zirconium and hafnium separation, and started production of zirconium sponge by this new process in September 1979. The process utilizes selective extraction of zirconium oxysulfate using high-molecular alkyl amine, and has the following advantages: 1. This extraction system has a separation factor as high as 10 to 20 for zirconium and hafnium in the range of suitable acid concentration. 2. In the scrubbing section, removal of all the hafnium that coexists with zirconium in the organic solvent can be effectively accomplished by using scrubbing solution containing hafnium-free zirconium sulfate. Consequently, hafnium in the zirconium sponge obtained is reduced to less than 50 ppm. 3. The extractant undergoes no chemical changes but is very stable for a long period. In particular, its solubility in water is small, about 20 ppm maximum, posing no environmental pollution problems such as are often caused by other process raffinates. At the present time, the zirconium and hafnium separation operation is very stable, and zirconium sponge made by this process can be applied satisfactorily to nuclear reactors.
Hafnium
Data scrubbing
Raffinate
Separation process
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To master the chemical behavior of the extraction of hafnium from zirconium in the diisobutyl ketone(DIBK)-TBP system and to guide the practical application of the DIBK-TBP system,the mechanism and characteristics about synergistic extraction of zirconium and hafnium by DIBK and TBP from thiocyanic acid medium were studied through the methods of slope coefficient and saturated volumetric.The results show that hafnium is extracted preferentially in DIBK-TBP system,the reactions of extraction follow the solvate theory.The composition of extracted complex was determined as n(Zr4+(Hf4+)):n(TBP):n(DIBK)=1:1:1,and identified as Zr(SCN)4?TBP?DIBK and Hf(SCN)4?TBP?DIBK,and the possible synergistic extraction complexes structures were further confirmed through the infrared spectra of the loaded organic phase.The extraction and separation effect for zirconium and hafnium can be improved with synergistic mixture of DIBK and TBP.
Hafnium
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Chemical properties of zirconium and hafnium is very similar,the extraction of zirconium and hafnium separation is main method. The mechanism of different solvent extraction separation of zirconium and hafnium was reviewed,such as MIBK extracting hafnium,( DIBK)-P204 extracting hafnium,TBP extracting zirconium,N235-H2SO4 extracting zirconium,and the mechanism of other solvent extraction system,petroleum sulfoxide,Versatic Acid10,Cyanex301,LIX 84-IC,etc. The application of relatively mature system of extraction separation of zirconium and hafnium in industrial were compared,and the promote industrialization direction of the extraction separation of zirconium and hafnium were discussed as follows: the new extractant research,extraction agent modification of existing research,minimum consumption extractant,the new extraction technology of short time extraction research.
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A solvent extraction method has been employed to extract and separate zirconium and hafnium from the nitric acid medium using Cyanex-272 and its mixture with TBP in kerosene. The effects of the experimental parameters such as contact time between phases, aging time, nitric acid concentration, Cyanex-272 and TBP concentration on the metals separation, and various stripping agents on the metals back extraction from the loaded organic phase have been investigated. The maximum separation factor of 16 was obtained in the single extraction system with 1% (v/v) Cyanex-272 from 2.5 M HNO3 solution. The combination of Cyanex-272 with TBP exhibited a significant synergistic effect for Zr extraction and the antagonistic effect for Hf extraction. The proposed novel synergistic mixture consisting of 0.5% (v/v) Cyanex-272 and 20% (v/v) TBP in kerosene offered the maximum separation factor of 99.7 from 2.5 M HNO3 solution. By applying a slope method, the extracted zirconium species were proposed to be ZrO(NO3)2·2Cyanex272·2TBP in the organic phase. Among the investigated stripping agents, 4 M H2SO4 solution showed the best efficiency for the stripping of zirconium and hafnium from the loaded mixture of Cyanex-272 and TBP with separation factor of 10.1.
Nitric acid
Hafnium
Stripping (fiber)
Kerosene
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To master the chemical behavior of the extraction of hafnium and zirconium in the mixture of diisobutyl ketone(DIBK) and P204,the characteristics and mechanism about the extraction of zirconium and hafnium by DIBK-P204 system in thiocyanic acid(HSCN) medium were studied through the methods of slope coefficient and saturated volumetric.The results show that hafnium is extracted preferentially by DIBK-P204 system,the synergistic extractive effects are found,and the extraction reactions follow the mechanism of the addition reactions.The composition of extracted complex is determined as n(Zr4+(Hf4+)):n(P204):n(DIBK)=1:2:1 and the extracted complexes are identified as Zr(SCN)3 HA2 DIBK and Hf(SCN)3 HA2 DIBK,and the possible synergistic extraction complex structures are suggested through infrared spectrum analysis of the loaded organic phase.The extraction and separation effect of zirconium and hafnium can be improved with synergistic mixture of DIBK and P204.
Hafnium
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Hafnium
Separation (statistics)
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Hafnium
Separation (statistics)
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