A new process for the separation of hafnium from zirconium

A new process for the separation of hafnium from zirconium has been developed. This process is based on the repeated reaction of the mixed tetrachloride vapors of zirconium and hafnium with alkali metal chloride salts in a solid form; hafnium tends to remain in the condensed phase while zirconium concentrates in the vapor phase. This process has been investigated experimentally as a function of the alkali chloride salt, the number of reaction steps and the mass ratio of vapor-to-condensed phases. The mechanism of the separation process is discussed in terms of thermodynamic considerations and the calculation of the theoretical separation efficiency is in agreement with the experimental results.     

DIBK-TBP萃取分离锆铪的热力学研究

对二异丁基甲酮(DIBK)和TBP从HSCN介质中协同萃取锆铪的性能及热力学进行研究,采用对数函数外推法求得DIBK-TBP体系萃取反应的热力学平衡常数分别为log(K12,Zr)=4.73和log(K12,Hf)=-5.09,锆铪与SCN-形成配合物Zr(SCN)3+和Hf(SCN)3+的稳定性常数分别为1×109.86和1×10-0.80,而铪的分配比在硫氰酸盐存在时要大于锆的分配比,说明过渡金属离子锆和铪在硫氰酸盐存在时与一般金属离子与配位体形成的配合物的稳定性常数愈大,金属离子的分配比愈大的规律相矛盾,并计算出萃取反应的焓变分别为ΔHZr=-11.43 kJ.mol-1和ΔHHf=-7.80 kJ.mol-1,说明对锆铪的萃取反应为放热反应,升高温度不利于萃取反应的进行,常温下自由能变分别为ΔGZr=-26.54 kJ.mol-1和ΔGHf=28.57 kJ.mol-1,熵变分别为ΔSZr=51.54 J.(K.mol)-1和ΔSHf=-124.07 J.(K.mol)-1,说明铪离子比锆离子更易与SCN-形成配位键,从而生成中性分子Hf(SCN)4与有机相发生溶剂化作用而进入有机相中。     

Separation of zirconium from hafnium in nitric acid solutions by solvent extraction using dibutyl butylphosphonate: Part 2. Mixer-settler runs

A process for zirconium/hafnium separation based on the distribution data given in Part 1 (Brown and Healy, 1978) has been successfully tested in a 10-stage Croda mixer-settler. The hafnium content of the zirconium could be reduced below the specification for nuclear grade zirconium. Purification of the zirconium from uranium could be achieved, and the hafnium could be recovered if desired. A flowsheet is presented.     

DIBK溶剂萃取法分离锆铪

以二异丁基甲酮(DIBK)作萃取剂,以TBP或P204作改质剂,从不同酸性介质中萃取分离锆铪。考察酸性介质、TBP加入量、P204加入量和盐析剂(NH4)2SO4等对萃取分离锆铪效果的影响。结果表明:DIBK只有在HSCN介质中优先萃取铪,改质剂TBP或P204的加入能显著增加铪的萃取率和锆铪的分离系数。锆铪的分离系数可达到9,与MIBK萃取分离锆铪的性能相似。     

Continuous ion exchange separation of zirconium and hafnium using an annular chromatograph

A pressurized continuous annular chromatograph (CAC) has been developed for truly continuous ion exchange preparative separations. This device utilizes a slowly rotating annular bed of sorbent material, fixed multiple feed points, and fixed withdrawal locations. Most of our investigations have been performed with a CAC of 280 mm diameter and 600 mm in length, but a larger model has recently been designed and constructed. A detailed study has been made of the separation of copper, nickel, and cobalt components from a simulated carbonate leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Recent studies have investigated the ion exchange separation of zirconium and hafnium from a sulfate feed solution. Nuclear reactor-grade zirconium, containing < 0.01% hafnium by weight, and hafnium, containing <1% zirconium, have been continuously prepared using cation exchange resin in the pressurized CAC. This device, because of its continuous feed and product withdrawal, its adaptability to largescale operations, and its ability to separate many components, is expected to make chromatography a more competitive process in the industrial sector.     

合金渣中铪的MIBK萃取分离试验

采用MIBK作为萃取剂,在盐酸体系下,对含铪合金渣中的铪进行萃取分离试验,主要考察合金渣中含量较高的锆、钛、铬和铪在萃前液不同氢离子浓度、NH4SCN浓度、有机相HSCN浓度及相比下的分离性能。结果表明,铪和锆钛分离难度较大、和铬分离较易,铪的最优分离条件为:萃前液氢离子浓度0.96mol/L、萃前液NH4SCN浓度2.56mol/L、有机相HSCN浓度2.73 mol/L、相比1。在最优条件下,铪和锆的相对分离系数为6.63,铪的分配比为1.79,对于锆含量较低的合金渣,可以有效提升锆铪分离效率,钛最好于萃取分离前进行分离。     

DIBK-P204体系萃取锆和铪的动力学

研究了DIBK-P204体系萃取锆和铪的动力学,采用恒界面池法考察搅拌速度、界面积和温度对锆和铪萃取速率的影响。结果表明,DIBK-P204体系对锆和铪萃取速率符合准一级反应,萃取反应的控制类型分别为相内反应控制和混合控制,对锆和铪萃取的表观活化能分别为-32.193kJ/mol和-18.984kJ/mol,升高温度不利于萃取反应的进行。     

DIBK-P350和DIBK-TOPO负载有机相中铪和锆的反萃

分别以盐酸、硫酸、碳酸氢铵、碳酸铵和碳酸钾的水溶液为反萃剂,对比研究了其对DIBK-P350体系和DIBK-TOPO体系负载有机相中铪和锆的反萃性能。结果表明,盐酸、硫酸、碳酸氢铵和碳酸钾对这两个体系负载有机相中铪和锆的反萃率或分离系数较低,不适合作为该体系的反萃剂,而碳酸铵((NH_4)_2CO_3)较适合作为反萃剂。在室温、油水相比O/A=1/2、(NH_4)_2CO_3浓度1.5~2.0mol/L的优化条件下,DIBK-P350体系负载有机相中(NH_4)_2CO_3对铪的单级反萃率和锆铪的分离系数分别达到91.61%和6.94。对DIBK-TOPO体系负载有机相反萃的优化条件为:室温、油水相比O/A=1/2、(NH_4)_2CO_3浓度2.0 mol/L,(NH_4)_2CO_3对铪的单级反萃率和锆铪的分离系数分别达94.33%和15.30。     

DIBK协萃体系负载有机相反萃行为研究

以不同酸度的盐酸和硫酸为反萃剂从DIBK-TBP体系和DIBK-P204体系负载有机相中反萃锆、铪。结果表明,对DIBK-TBP体系负载有机相,先采用酸度为2.0mol/L的盐酸水溶液对锆进行反萃,单级反萃率达85%,得到富锆液,然后用酸度为8.0mol/L的硫酸水溶液对铪进行反萃,单级反萃率达90%,得到少锆的铪液;对DIBK-P204体系负载有机相,先采用酸度为3.0mol/L的硫酸水溶液对铪进行反萃,单级反萃率达90%,得到少锆的铪液,然后采用酸度为2.0mol/L的盐酸水溶液对锆进行反萃,单级反萃率达70%,得到少铪的锆液。采用盐酸和硫酸可顺利实现对DIBK体系负载有机相中锆、铪的反萃取。     

两种快速测定锆铪的光度法

研究了锆和铪的二甲酚橙络合物在高氯酸介质中、硫酸钠下存在的吸收光谱,结果表明:在高氯酸介质中,Zr(Ⅳ)-XO,λmax为555~558 nm;Hf(Ⅳ)-XO,λmax为535 nm。在常温下,Hf(Ⅳ)-XO在558 nm和500 nm处的吸光度比值稳定。对锆铪混样可用双波长K系数法测出锆的含量,用差减法求出铪的量,此法适用范围为锆(铪)0~25μg/25 mL;在低温(0~5℃)时,有硫酸钠存在的条件下,铪被有效隐蔽,测出锆的含量,再结合EDTA滴定法可求出铪的含量,该法适用范围为锆0~30μg/25 mL,铪0~40μg/25 mL。两种测定分析方法的相对误差均在10%以下。     

DIBK-TBP体系萃取铪和锆的动力学研究

在恒界面池中研究DIBK-TBP协同萃取体系萃取铪、锆的动力学,考察了温度、界面积和搅拌强度等对萃取速率的影响。结果显示,DIBK-TBP体系萃取铪和锆的过程符合一级动力学反应;对铪的萃取为相内反应和扩散共同影响的混合控制类型,表观活化能-43.106kJ/mol;对锆的萃取与搅拌强度、比界面积无关,为相内反应控制类型,表观活化能-16.024kJ/mol。     

Determination of optimum process conditions for the extraction and separation of zirconium and hafnium by solvent extraction

Taguchi's method was used to determine the optimum conditions for separation of zirconium from hafnium by solvent extraction. The experimental conditions were studied in the range of 0.1 to 2.0 M for three different acids and TBP, D2EHPA or Cyanex 272 as extractant. The optimum extraction of zirconium was 71% when 2.0 M nitric acid and Cyanex 272 were used. The optimum zirconium/hafnium separation was also achieved using this combination.     

Separation of zirconium and hafnium fluorides by the sublimation–sorption method

A preparation method of zirconium tetrafluoride (ZTF) of the nuclear degree of purity for one separation stage is proposed and confirmed experimentally. For this purpose, initial ZTF vapors should be passed inside the powderlike zirconium dioxide layer 140–150 mm in height or above its layer 1000–1100 mm in length. A process cascade for the fabrication of nuclear-pure ZTF and HTF with the hafnium content higher than 99% for one separation stage in the absence of process wastes is developed and calculated. It is shown that the proposed process cascade for the separation and concentration of ZTF and HTF for one stage makes it possible to prepare ZTF with a hafnium content up to 0.01 wt % from the initial ZTF with a hafnium concentration of 2.0 wt % and a hafnium concentrate with a hafnium content higher than 99%.     

我国锆材料现状及江西锆业发展思路

简要介绍了锆铪资源的分布、特点，在国民经济和国防建设中的意义；重点叙述了我国锆铪工业的发展历史、锆材料现状以及锆铪产品与锆铪产品的生产工艺、技术水平，锆铪材料贸易及应用前景，同时，介绍江西锆业状况与今后的发展思路。     

Technologies of secondary refractory rare metals (Review)

A short review of works by A.V. Elyutin et al. in the field of rare metals is presented. Technologies of the recovery of zirconium, hafnium, tungsten, tantalum, and niobium from various types of secondary raw materials, notably, scrap metal, scrap of refractory materials, wastes and scrap of hard alloys, and obsolete scrap of capacitors, are considered. Possibilities of increasing the purity of these metals by electrolytic refining and electron-beam melting are shown.     

电感耦合等离子体原子发射光谱法测定铪合金中锆

使用硝酸和氢氟酸溶解样品,以Zr 327.305 nm为分析谱线,建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定铪合金中锆含量的分析方法。结果表明:铪质量浓度在100 μg/mL以下时,对锆的测定结果影响不显著,不需要使用基体匹配法绘制校准曲线;由于酸度对锆的测定结果有影响,待测试液与标准溶液系列的酸度应该保持一致,酸度大约为1.0 mol/L。锆的质量浓度在0.2～5.0 μg/mL范围内与发射强度呈线性,校准曲线的线性回归方程为y=39 966 x+176,相关系数r=0.999 7。方法中锆的检出限为0.001 5 μg/mL。实验方法用于铪合金样品中锆的分析,测定结果的相对标准偏差(RSD,n=6)小于1%,回收率为99%;同时与X射线荧光光谱法的测定结果进行比对,两种方法测定结果基本一致。     

N236-HSCN体系萃取分离锆铪的盐效应研究

以乙酸戊酯作为稀释剂,采用N263-HSCN体系对锆、铪进行萃取分离,分别研究了(NH4)2SO4、NH4Cl、NH4NO3、NaCl和MgCl2等盐析剂的种类和浓度对锆与铪萃取分离的影响。结果表明,N263-HSCN体系分离锆、铪时优先萃取铪,该体系中SCN-的稳定性要比MIBK-HSCN体系强。不同阳离子的盐析剂对锆和铪的萃取率影响顺序为：NaCl>MgCl2>NH4Cl,对分离系数影响不大。不同阴离子的盐析剂对锆的萃取率顺序为：NH4NO3>NH4Cl>(NH4)2SO4,铪的萃取率顺序为：(NH4)2SO4>NH4Cl>NH4NO3,而分离系数顺序为：(NH4)2SO4>NH4Cl>NH4NO3,与阴离子的水合能力强弱顺序一致。当(NH4)2SO4加入量为0.6 mol/L时,分离系数达18.56,此时对锆和铪的萃取率分别为41.72%和93%。     

The separation of zirconium and hafnium in a molten salt-molten zinc system

The commercial separation of zirconium and hafniumvia aqueous/organic extraction procedures is both difficult and expensive. The principal objective of the present work was to study an alternative procedure involving the oxidation-reduction equilibria of zir-conium and hafnium between a molten salt phase and molten zincvia the displacement reaction: Zr(IV)_{molten salt} + Hf_{molten zink} ⇌ Hf(IV)_{molten salt} + Zr_{molten zink} The reaction goes strongly to the right with an equilibrium constant: logK =0.432 ×10⁴/T - 1.565 for Na₂Zr(Hf)F₆ dissolved in NaKCl₂ solvent, thus showing promise as the basis for an anhydrous process for separating zirconium and hafnium. The rate of approach to chemi-cal equilibrium was studied in a baffled stirred reactor. The equilibration rate was found to be controlled by the hafnium mass transfer rate from the molten zinc to the metal-salt interface. The mass transfer rate could be estimated from the physical properties of the molten metal and the salt phases, using the Mayer correlation. Formerly with the Teledyne Wah Chang Cor-poration, Albany, OR.     

Decomposition kinetics of the supersaturated solid solution in Al-Mg2Si alloys with scandium,zirconium, and hafnium additions

The decomposition kinetics of the aluminum-based supersaturated solid solution in Al-Mg₂Si alloys with some transition metal additions is studied by hardness and electrical resistivity measurements, optical microscopy, and scanning electron microscopy. The effect of only scandium or scandium along with zirconium and hafnium on the hardening of the Al-Mg-Si alloys after heat treatment, which includes quenching, natural aging, and artificial aging, is revealed. The artificial aging temperature at which the hardening is maximal is chosen.     

Production of high-purity hafnium and the study of some its properties

High-purity hafnium samples are prepared by crucibleless zone melting in a deep vacuum. The impurity composition and microhardness of the samples are studied over their length. The electrical conductivity and thermal conductivity of hafnium samples with various zirconium contents are determined. The temperature dependences of the ultrasound absorption coefficient in single-crystal hafnium are investigated along various directions, and the causes of absorption of ultrasonic waves with frequencies of 20, 50, and 150MHz are explained.