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Introduction. Zirconium is always accompanied by hafnium in nature and therefore termed congeneric. Zircon (ZrSiO 4) and baddeleyite (ZrO 2) are the major minerals for zirconium and contained more than 0.5% hafnium, which originates from the substitution of zirconium in the crystal lattice (Taghizadeh et al., 2011).Zirconium has …Web
journal article: determination of zirconium with hafnium in zircon via paper chromatographic separationWeb
Cyclohexanone was found to be a very excellent extraction solvent for the mutual separation of zircorium and hafnium. The distribution ratio (D: the ratio of the concentration of zirconium or hafnium in orgaric phase to that in aqueous phase) and the separation factor (the ratio of D/sub Hf//D/sub Zr/) in this extraction were measured chiefly at 30 deg C. …Web
BEAP (B) was used to separate zirconium from hafnium with a separation factor of 6.8 under optimum conditions. The content of HfO 2 in ZrO 2 product was decreased from 3% in the feed to 0.6% in the Zr product after counter-current operation. The extracted complexes can be determined to be ZrO(HSO 4) 2 ·3B and HfO(HSO 4) 2 ·2B …Web
Zirconium or hafnium was stripped from the organic phase with mineral acids and determined spectrophotometri- cally as the complex with Arsenazo III [10] or xylenol orange [11], respectively. RESULTS AND DISCUSSION Extraction as a function of crown ether con- centration The optimum concentration of DC-18-crown-6 for extraction or …Web
The concentrations of zirconium and hafnium were determined by energy dispersive X-ray fluorescence spectrometry - EDXRF (Shimadzu - EDX 720), whereas the concentration of the nitrate was determined by molecular absorption spectrophotometry in the ultraviolet region (302 nm) through a UV–visible spectrophotometer (Varian - Cary 50 …Web
Dialkylphosphinic acids with stronger extraction ability show better zirconium/hafnium separation performance at higher acidity of 2.0 mol L-1 H2SO4, while those with weaker extraction ability ...Web
After washing, atomic-level zirconia containing hafnium <0.01% can be obtained. The hafnium in the raffinate is enriched to 50% to 70%, and then extracted by P204, and the zirconium and hafnium are further separated to obtain atomic energy level hafnium oxide containing more than 96% of hafnium. This process has low material …Web
A method is provided to optimize separation of zirconium from hafnium by extraction of a feed mix including (Zr+Hf)OCl 2 with a thiocyanate-containing organic phase. The method includes maintaining the TA/MO 2 ratio in a range from greater than about 2.55 to about 3.5. ... Uranium-preextraction in zirconium/hafnium separations process ...Web
Density functional theory (DFT) is employed to investigate ferroelectric (FE) hafnium–zirconium oxide stack models for both metal–insulator–metal (MIM) and metal–insulator–semiconductor (MIS) structures. The role of dielectric (DE) interlayers at the ferroelectric interfaces with metals and semiconductors anWeb
16 Timothy Adams, "Zirconium and Hafnium," from Mineral Facts and Problems, U.S. Bureau of Mines, 1985, pp. 941-956. A less complicated method may be found to separate hafnium from zirconium and to refine the hafnium. A new process is being developed where zirconium and hafnium are separat ed by fractional distillation of the zirconium ...Web
1. Introduction. Zirconium and hafnium are two of the most important nuclear materials [1].They are mainly used for cladding nuclear reactor fuels and control rods due to their extremely opposite absorption characteristics for thermal neutrons, respectively [2], [3].The purity of Zr and Hf has a direct compact on the efficiency and security of reactor …Web
Nuclear grade zirconium and hafnium are important materials in nuclear power plants, which are usually produced with solvent extraction and separation …Web
Nuclear-grade zirconium (Zr) and hafnium (Hf) play an inevitably strategic role in the sustainable development of the nuclear industry. However, the efficient separation of Zr ions and Hf ions is still problematic due to their approximate ionic radii. This work, provides a novel strategy for separating Zr ions and Hf ions by solvent extraction ...Web
This work, provides a novel strategy for separating Zr ions and Hf ions by solvent extraction using an HCl solution containing the green amic acid N, N-di-2 …Web
The disadvantages of these processes could be largely avoided if it were feasible to separate hafnium and zirconium, using another extractants. Previous reports have used Cyanex 925, Cyanex 923, 3 Aliquat 336, 4 Cyanex 272 5 and D2EHPA 6 for zirconium/hafnium separation [4], [5], [6]. The comparison of these works shows that …Web
whereas hafnium is used as an excellent control rod material for reactors due to its high neutron-absorption capacity. The efficiency of the reactor depends directly on the concentration of hafnium in zirconium. The zirconium should contain a very low concentration of hafnium, not exceeding 100 ppm, for use in the nuclear industry.Web
Entirely aqueous solution-gel route for the preparation of zirconium carbide, hafnium carbide and their ternary carbide powders Ceramics – Silikáty 60 (3) 248-253 (2016) 249 carbide precursors were concerned, the metal source was comprised of zirconium and hafnium salts in the molar ratios 0.5Hf:0.5Zr and 0.9Hf:0.1Zr and the otherWeb
A. van Sandwijk. Zr-Hf-Ti Metallurgie B.V.; Van der Heimstraat 62, Den Haag, SB, The Netherlands. Search for more papers by this authorWeb
A technique is described for the solvent extraction of zirconium. In this method, zirconium has been extracted quantitatively from 0.005 M sodium salicylate solution at pH 2.5-3 using 0.01 M ...Web
Zirconium and hafnium are corrosion-resistant metals that are widely used in the chemical and nuclear industries. Most zirconium is consumed in the form of the main ore mineral zircon (ZrSiO4, or as zirconium oxide or other zirconium chemicals. Zirconium and hafnium are both refractory lithophile elements that have nearly identical charge, ionic …Web
Properties and Applications of some Zirconium and Hafnium Compounds. Decomposition of Zirconium Ores. Preparation of Zirconium Compounds and …Web
Zirconium is an ideal material for nuclear reactors due to its low absorption cross-section for thermal neutrons, whereas the typically contained hafnium with strong neutron-absorption is very harmful for zirconium. This paper provides an overview of the processes for separating hafnium from zirconium. The separation processes are roughly ...Web
In the present study, a simple versatile extraction method based on supramolecular solvent microextraction followed by inductively coupled plasma atomic emission spectrometry was developed for the extraction, separation and determination of zirconium (Zr) from hafnium (Hf). Zr and Hf were complexed with bis(2,4,4 …Web
Zirconium is an ideal material for nuclear reactors due to its low absorption cross-section for thermal neutrons, whereas the typically contained hafnium with strong neutron …Web
This is an improvement to a process for making zirconium metal from uranium-containing zircon ore. The process being improved is of the type which utilizes a fluidized bed carbochlorination process of the zircon ore in which uranium chloride is volatilized at the ore chlorinator temperature and follows as an impurity in the zirconium-hafnium …Web
This is an improvement to a process for making zirconium metal from uranium-containing zircon ore. The process being improved is of the type which utilizes a fluidized bed carbochlorination process of the zircon ore in which uranium chloride is volatilized at the ore chlorinator temperature and follows as an impurity in the zirconium-hafnium …Web
A se paration experiment was made in which a mixture of 97.8% Zr and 2.2% Hf (W/W) was extracted with 0.2 M TNOAcyclohexane in 8 M HCl + 0.7 M HNO/sub 3/. With a single contact the hafnium content was brought down to …Web
The equilibrium adsorption capacity (Q e, mg/g) and distribution coefficient (D) were calculated with the following formulas: m V ccQ ⋅−= )( e0e (1) m V c cc D ⋅ − = e e0 (2) where c 0 is the initial total metal concentration of zirconium or hafnium in solution, g/L; c e is the equilibrium concentration of zirconium or hafnium in ...Web
