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1.
《分离科学与技术》2012,47(9):1341-1344
The weight distribution coefficients (λM) of the most often occurring in zirconium salts ions (M(II), M(III) and M(IV)) have been determined in established earlier optimal conditions for separation of zirconium from hafnium by means of Diphonix® resin. Their values range from 21 (λZn(II)) to 1830 (λTi(IV)) and depend on the charge of M ion as well as on its radius. For ions of the highest λM (Ti(IV) and Fe(III)) their influence on hafnium – zirconium separation has been studied. Ti(IV) ions at concentration of 1% (in relation to Zr) has been found to noticeably affect separation of hafnium from zirconium by means of Diphonix® resin. 相似文献
2.
The effect of the temperature and pH of chemical precipitation on the degree of agglomeration of zirconium and hafnium hydroxides
has been investigated. The specific features of crystallization of zirconium and hafnium hydroxides have been revealed. A
technological scheme has been proposed for synthesizing ZrO2 and HfO2 nanocrystalline powders. 相似文献
3.
Sibnath Mazumdar Hem Shanker Ray 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1972,22(5):565-576
A pyrometallurgical method for partial separation of hafnium from zirconium has been investigated. The method involves continuous reaction between a flowing gas mixture of zirconium tetrachloride and hafnium tetrachloride with solid sodium chloride in a packed bed reactor. The solid-vapour reaction enriches the vapour phase with respect to zirconium tetrachloride. This may be attributed to a more favourable reaction for hafnium tetrachloride. The influence of a number of parameters, e.g. temperature, gas flow rate, particle size and bed length, has been studied. Decreases in flow rate and particle size and increase in bed length are found to favour separation, while temperature has little effect. A simple equation has been derived to explain the experimental observations. 相似文献
4.
介绍了在离子交换固定床上用D296强碱性阴离子交换树脂分离锆、铪的洗脱实验研究。吸附与洗脱实验的温度均控制在2~5℃,洗脱实验在饱和吸附的离子交换柱、过漏的离子交换柱、未过漏的离子交换柱中进行。研究结果表明:离子交换柱吸附状态以及洗脱剂酸度对分离效果有显著的影响。当离子交换柱存在交换区时,用任何酸度的硫酸作为洗脱剂,铪均被先洗脱出来,但高酸度的洗脱剂对分离锆、铪更有利;当离子交换柱为饱和状态时,低酸度和高酸度的洗脱剂洗脱,锆、铪不能得到分离。实验证明了单一的固定床分离锆、铪的效率低,要成功实现锆、铪的分离,需采用连续分离的离子交换移动床。 相似文献
5.
《分离科学与技术》2012,47(6):755-766
Abstract The separation of zirconium and hafnium by the fractional precipitation method has been extended by coprecipitation of their pyrophosphates. In the presence of sulfate ion, fractional precipitation of zirconium-hafnium pyrophosphates from a solution in 4 N HCI gives a good separation factor. Hafnium becomes concentrated in the precipitate. At a concentration of 0.7 to 0.8 g Zr/100 ml, optimum results were obtained with the addition of about 50 g ammonium sulfate/100 ml (Λ > 5). The separation factor falls sharply at higher concentrations of zirconium. Moreover, it has been found that when precipitation of the host is done above 45%, the separation factor shows a declining trend. It was, therefore, not possible to prepare reactor-grade zirconium in a single stage. After several trials it was possible to find nearly optimum conditions for the separation. Finally, reactor-grade zirconium was obtained in three stages of precipitation with an yield of ~24%. 相似文献
6.
锆、铪与钪物理化学性质相似且难以分离,是导致氧化钪纯度不高的主要原因之一。为解决这一问题,本文采用邻碘苯甲酸铵作为沉淀剂,去除粗氧化钪中的锆、铪杂质,通过优化不同实验参数得到最佳工艺条件。在实验研发基础上本工艺进行工业生产,进一步验证及完善了工艺条件。得出在溶液酸度为0.1mol/L、沉淀剂加入量为理论量的1.1倍、100℃保温条件下搅拌30min时处理效果最佳。利用氨水与锆、铪沉淀反应回收沉淀剂,通过FTIR和SEM对锆和铪原沉淀与现沉淀进行表征,高效液相色谱对滤液进行分析,结果表明原沉淀物反应生成氢氧化物和邻碘苯甲酸铵。工业实验中钪和邻碘苯甲酸铵回收率分别为99.54%和95.19%,锆、铪去除率均为99.6%。 相似文献
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10.
Chemical-grade zirconium contains about 1–3 wt% hafnium, which is harmful for nuclear applications due to its high neutron-capture cross section. In the present paper, Zr-Hf separation in Sn-Cu-Zr-Hf and Cu-Zr-Hf alloy systems using molten salt containing CuCl2 or CuF2 was thermodynamically evaluated and lab-scale experiments on zirconium and hafnium separation in different molten salt systems were conducted. The best single-step Hf removal efficiency and Zr-Hf separation factor of about 95% and 9.0, respectively, were obtained with a NaCl-CaCl2-CuCl2 (3 wt%) molten salt system at 850°C and the CuCl2/Hf stoichiometric ratio of 1.5. 相似文献
11.
Copper immersion coating of magnesium alloys has, to date, been conducted only in acidic baths. This article describes a novel
alkaline bath for copper immersion coating on AZ91D magnesium alloy. Prior to the coating process, a chemical etching process
of the magnesium substrate was optimized using orthogonal experimental methodology. The copper immersion coating was then
investigated with regard to the effect of pH and fluoride content in the deposition bath. It was revealed during the coating
process that an increase of pH and fluoride content led to a surface film formation on the magnesium substrate. The surface
film formation occurred simultaneously with copper reduction, rendering a controlled magnesium dissolution, thereby a controlled
copper deposition. With optimized conditions of chemical etching and immersion coating processes, uniform copper deposits
were achieved. 相似文献
12.
Subbaiah Muthu Prabhu S. SD. Elanchezhiyan Giehyeon Lee Sankaran Meenakshi 《Journal of Inorganic and Organometallic Polymers and Materials》2016,26(4):834-844
The dicarboxylic acids like oxalic acid, malonic acid and succinic acid mediated graphene oxide–zirconium needle like complexes were synthesized and used to remove fluoride from simulated fluoride contaminated water. The adsorption of fluoride by dicarboxylic acids mediated graphene oxide–zirconium complexes were by both electrostatic interaction at acidic pH and ion-exchange mechanism at neutral pH. The maximum defluoridation capacity observed was 9.70 mg/g at the minimum contact time of 18 min at room temperature. Various batch equilibrium parameters like pH studies, contact time, common ion interference and temperature studies were optimized. The synthesized graphene oxide and graphene oxide supported complexes were characterized using UV–vis, FTIR, XRD and SEM with EDAX analysis to establish the mechanism of fluoride adsorption. The removal of fluoride was described by the pseudo-second-order reaction kinetics, Freundlich isotherm model and thermodynamic studies which indicates the nature of adsorption was endothermic and spontaneous. Regeneration studies depict that the dicarboxylic acid mediated graphene oxide–zirconium complex can be used as an effective adsorbent for the removal of fluoride ions from wastewater. Also, the field applicability of the material has been verified with field samples collected from nearby fluoride endemic villages. 相似文献
13.
M. M. Hefny 《Journal of Applied Electrochemistry》1991,21(6):483-486
Study of the chemical stripping of anodic oxide films on hafnium, zirconium, tungsten and aluminium has led to the deduction of the morphology of the respective oxides. Away from the boundary region hafnium oxide is a compact, smooth, homogenous and crystalline oxide. Zirconium oxide has a superficial disorder layer which constitutes about 17% of the entire film. Tungsten oxide deposits are composed of two defective partial layers the outer one being more disordered. Aluminium oxide is a porous film. A schematic representation of each film had been presented. 相似文献
14.
A method of preparing the disilicides of titanium, zirconium, and hafnium is outlined. Unit-cell dimensions, density, Knoop microhardness numbers, chemical analyses, and solubility in various reagents are given for the three compounds. It is concluded that these disilicides have no value as industrial hard materials. 相似文献
15.
Bruce A. Pint 《Journal of the American Ceramic Society》2003,86(4):686-95
It is well-known that the addition of reactive elements (including yttrium, zirconium, lanthanum, cerium, and hafnium) improve the high-temperature oxidation performance of alumina-forming alloys. Less studied are strategies for optimizing these additions for developing a high-performance, wrought FeCrAl alloy with maximum oxidation-limited component life. Results from the literature are summarized regarding potential improvements. One promising strategy is the addition of two reactive elements, such as yttrium and hafnium, which has been effective in commercial and laboratory nickel-based alloys and appears to impart the expected benefits, such as reducing the scale growth rate while minimizing detrimental effects, such as the formation of reactive element-rich oxides in the scale and internal oxidation. Although there are promising data, the long-term studies are not yet complete, and it is difficult to predict if "co-doped" FeCrAl alloys will produce superior oxidation-limited lifetimes in high-temperature environments. 相似文献
16.
《分离科学与技术》2012,47(9):1927-1940
Abstract The extraction of zirconium and hafnium from aqueous HCl solutions by means of Aliquat 336 in organic diluents was systematically studied. The following three aspects were discussed: the extraction dependence on HCl, the Aliquat 336 concentrations, and the nature of diluents. Both of the metals were stripped with deionized water and the influence of phase ratio on the efficiency of the stripping has been investigated. The stoichiometry of the extracted Zr and Hf species from single metal ion were studied and a possible extraction mechanism for the Zr‐Hf mixture is discussed in the light of the results obtained. 相似文献
17.
Z. HUBICKI 《溶剂提取与离子交换》2013,31(1):183-198
Results of the studies on separation of hefnium /IV/ from zirconium /IV/ by frontal analysis on chelating ion-exchangers of different types have been presented. The phosphonic ion-exchanger Duolite ES-63 proved to be the best in zirconium sulphate purification from hafnium /IV/ among the examined chelating ion-exchangers. 相似文献
18.
Novel Method for Zirconium Oxide Synthesis from Aqueous Solution 总被引:1,自引:0,他引:1
Takeshi Yao Takashi Inui Akira Ariyoshi 《Journal of the American Ceramic Society》1996,79(12):3329-3330
A novel method for zirconium oxide crystal synthesis from an aqueous solution at ordinary temperature and pressure has been discovered. Boric acid was added to a sodium hexafluorozirconate solution, fluoride ion was consumed by the formation of BF− 4 complex ion, then the hexafluorozirconate ion was hydrolyzed to zirconium oxide in order to increase the amount of fluoride ion. The formation of zirconium oxide crystal was confirmed by clear X-ray diffraction peaks. This method is promising for preparing zirconium oxide films in various applications 相似文献
19.
《分离科学与技术》2012,47(9):2022-2040
Abstract 3-Phenyl-4-benzoyl-5-isoxazolone (HPBI) was synthesized and examined with regard to the synergistic solvent extraction behavior of zirconium(IV) and hafnium(IV) in the presence of various crown ethers (CEs), namely, 18-crown-6 (18C6), dicylohexano-18-crown-6 (DC18C6) and benzo-15-crown-5 (B15C5) from hydrochloric acid solutions. The results demonstrated that zirconium(IV) and hafnium(IV) were synergistically extracted into chloroform with mixtures of HPBI and CEs as ZrO(PBI)2 · CE and HfO(PBI)2 · CE, respectively. The complexation strength follows the order DC18C6 >18C6 > B15C5. The addition of CEs not only enhances the extraction efficiency of zirconium(IV) and hafnium(IV) but also significantly, especially in the presence of B15C5, improves the selectivity (Zr/Hf = 4.73) between these metal ions as compared to HPBI alone (Zr/Hf = 2.09). On the other hand, selectivity has been moderately decreased by the addition of 18C6 or DC18C6 to the metal-chelate system. 相似文献
20.
《分离科学与技术》2012,47(12):2711-2722
Abstract Sorption behavior of zirconium and hafnium on different commercial anion exchange resins with different amine functions; ammonium (Amberjet 4200Cl), pyridine (PVP) and pyridinium (HPQ) was investigated in hydrochloric acid by both batch and column methods. Experiments were studied as a function of the concentration of hydrochloric acid. For all resins, zirconium was preferably extracted. The highest separation factors at equilibrium conditions were obtained by poly(vinyl‐pyridine) (PVP) with a hydrochloric acid concentration of 9.5 M. It was observed that a single contact of the loaded resins with pure water completely back extracted the metal ions from the resins. On the basis of the significant difference between distribution coefficients of Zr and Hf, the separation was performed on a glass column (25×160 mm), packed with the resin. The breakthrough curves showed a competitive sorption and desorption process between Zr and Hf for the three resins studied. 相似文献