The separation of zirconium and hafnium in a molten salt ...
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 + …
The Ion-Exchange Separation of Zirconium and Hafnium ...
radioactive tracer technique, the run described below, involving milligrams of material, illustrates the applicability of the method to the production of significant amounts of pure hafnium and zir-conium. 35 mg. of zirconium oxide 15 mg. of hafnium oxide were dis-solved in sulfuric and hydrofluoric acids, hafnium and zirconium
Synthesis and X-ray crystal structures of ansa-complexes ...
Synthesis and X-ray crystal structures of ansa-complexes of titanium, zirconium, and hafnium involving methylene-bis(indenyl) ligand January 2001 Journal of Organometallic Chemistry 619(1):280-286
SEPARATION OF ZIRCONIUM FROM HAFNIUM BY ION …
Hafnium occurs in all zirconium ores usually in the range 2 - 3%. However, for the most nuclear industry applications, it is necessary to use a zirconium of extremely pure level. The current work consists in the separation of zirconium and hafnium by the ion exchange method in order to obtain a zirconium concentrate of high purity.
Corrosion of Hafnium and Hafnium Alloys
Corrosion of Hafnium and Hafnium Alloys D.R. Holmes, ATI Wah Chang, Allegheny Technologies HAFNIUMiselementnumber72.Itresidesin group IVA of the periodic table with titanium and zirconium. Hafnium is always associated with zirconium in minerals such as zircon and baddeleyite, usually in the range of 1 to 5%. The chemical similarity between ...
Hafnium | Hafnium
Hafnium: Hafnium metal is a mild irritant of the eyes, skin, and mucous membranes. No industrial poisonings involving hafnium have been reported. Zirconium: Zirconium is generally considered to be physiologically inert. Acute Toxicity: No data Carcinogenicity: NTP: Not identified as carcinogenic IARC: Not identified as carcinogenic
Hafnium - espimetals.com
Hafnium: Hafnium metal is a mild irritant of the eyes, skin, and mucous membranes. No industrial poisonings involving hafnium have been reported. Zirconium: Zirconium is generally considered to be physiologically inert. Acute Toxicity: No data. Carcinogenicity: NTP: Not identified as carcinogenic IARC: Not identified as carcinogenic
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Zirconium, hafnium, and the alloys produced from those metals are highly resistant to corrosion and high temperatures, making them particularly desirable for use in a variety of critical applications involving aggressive environments. Zirconium and hafnium are used in fuel rods that power nuclear reactors ...
Synthesis and X-ray crystal structures of ansa-complexes ...
Complexes of zirconium and hafnium involving chelating methylene-bis(indenyl) ligand have been prepared in a similar manner using transmetallation reaction . Mixtures of rac - and meso - methylene-bis(indenyl)zirconium and -hafnium dichlorides were prepared under a treatment of ZrCl 4 or HfCl 4, respectively, with tin derivatives of bis ...
EXTRACTION AND SEPARATION OF ZIRCONIUM AND …
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.
A thermodynamic model for reactive extraction of macro ...
Pure component thermodynamic models are developed for solvent extraction involving ionic reaction equilibrium for distribution of macro concentrations of zirconium and hafnium between an aqueous phase containing HNO 3 and an organic solvent phase containing diluted TBP. The concentration range considered is 10 −03 to 10 0 M. A framework based on …
Development of a process for the production of a high ...
hafnium oxide (based on hafnium and zirconium oxide content) to in excess of 90 weight per cent hafnium oxide in tw9 . 5 process cycles, each cycle involving an adsorption on silica gel followed by differential stripping of the adsorbate. It is estimated that 70% of the initial hafnium adsorbed can be recovered as 90 weight per cent hafnium ...
Simultaneous determinations of zirconium, hafnium, …
Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide Talanta . 2013 Nov 15;116:1085-90. doi: 10.1016/j.talanta.2013.08.019.
Emerging Research and Development | Zircon Industry ...
A growing portion of the zircon mined worldwide is used for the extraction of the metals zirconium and hafnium or their further processing to produce zirconium chemicals. There is a considerable number of further uses and it is clear from …
Hydrolysis of Zirconium and Hafnium Siloxide Complexes ...
Hydrolysis of Zirconium and Hafnium Siloxide Complexes. Isolation and Characterization of the Intermediate Aqua Complexes M[OSi(O t Bu) 3] 4 (H ... This indicates that the aqua ligand exchange occurs by an associative mechanism involving a seven-coordinate intermediate. On the basis of this observation, we postulate that the hydrolysis of 5 ...
Zirconium and hafnium in meteorites - PATZER - 2010 ...
Zirconium, Hafnium, Calcium, and Magnesium. As an additional approach of evaluating the inventory of refractory elements, we plotted Zr/Hf ratios as a function of CaO/MgO. Certain trends become identifiable . From a common cluster of Zr/Hf approximately 33 and CaO/MgO approximately 0.075, three paths emerge (1) H chondrites showing relatively ...
Preparation of Zirconium and Hafnium Metal Powders …
Article Preparation of Zirconium and Hafnium Metal Powders Using Fused Salt Electrolysis was published on April 1, 1995 in the journal High Temperature Materials and …
The Ion-Exchange Separation of Zirconium and Hafnium - …
In the course of a rather cursory examination of the elution of tetra-positive ions from the cation exchange resin Dowex 50 with hydrochloric acid solutions, the authors have discovered a very effective method of separating zirconium from hafnimu. In view of the great labor involved in preparing even reasonably pure hafnium compounds by existing methods, they feel that this …
ZIRCONIUM, HAFNIUM, TITANIUM, AND SILICON …
1. 1.-37. (canceled) 38. A deposition process, comprising contacting a substrate with a vapor of a precursor to deposit a film thereon containing at least one of zirconium, hafnium, titanium and silicon, wherein said precursor comprises a compound selected from the group consisting of compounds of the formulae: a) (R 1 NC(R 3 R 4) m NR 2) (OX−n)/2 MX n, wherein R 1, R 2, R …
Simultaneous determinations of zirconium, hafnium, …
Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide Raso, M. Censi, P. Saiano, F. …
The separation of zirconium and hafnium in a molten salt ...
Abstract. The commercial separation of zirconium and hafnium via 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 zinc via the displacement reaction: Zr(IV) …
Synthesis and crystal structure of some novel phases ...
zirconium halldes relative to those of hafnium is one of the few differences in the chemistry of the two elements. Larsen has proposed a separation scheme involving the reduction of zirconium tetrahalides containing hafnium in natural abundance to the appropriate zirconium trlhalide by either metallic
Titanium, zirconium and hafnium - Annual Reports Section ...
Highlights include some remarkable imide chemistry, notably from the Mountford laboratories, whilst applications involving TiO continue to multiply.
Chemistry of organo-zirconium and -hafnium compounds …
The zirconium and hafnium compounds are monoclinic with four molecules in the unit cell. The crystals belong to the space group P2/sub 1/ /a, which permits the existence of mirror images in the solid state. Attempts to resolve the possible racemic pairs of these anions were unsuccessful.
Titanium, Zirconium and Hafnium - ScienceDirect
Titanium, which comprises 0.63% (i.e. 6320 ppm) of the earth's crustal rocks, is a very abundant element (ninth of all elements, second of the transition elements), and, of the transition elements, only Fe, Ti and Mn are more abundant than zirconium (0.016%, 162 ppm). Even hafnium (2.8 ppm) is as common as Cs and Br.
Zirconium and hafnium 1994 - ScienceDirect
A group of amoborollide derivatives of zirconium and hafnium having both Lewis acidic and basic sites in relatively close proximity has been prepared. The compounds Cp* [t15C4BN (CHMe2)2)MCl1iCl (M = Zr, Hf) have been obtained by treatment of Cp*MC13 with L [C414BN (CH,Me2)21hf in toluene.
Hafnium and Zirconium-Machining - espimetals.com
Hafnium and Zirconium-Machining. Three basic machining parameters should be used for all operations involving zirconium and hafnium alloys: A flood coolant system using a water soluble oil lubricant. Zirconium and hafnium exhibit a marked tendency to gall and work-harden. Therefore higher-than-normal clearance angles on tools are needed to ...