Zirconium solubility

The hafnium to zirconium ratio can be reduced to only O Ol per cent or less, by 16 to 18 fractional crystallizations in stainless-steel vessels, between temperatures of 100°C and 19 C. At these temperatures the zirconium solubilities are respectively 250 g/1. and 16-3 g/1. Hafnium solubilities are somewhat higher. Since the overall yield, using fresh water for each crystallization stage, would only be about 10 per cent, the mother liquor from each stage is passed back to a previous stage for a later batch. In this way an overall yield of 80 per cent of the zirconium is obtained. 

Deodorants and antiperspirants Aluminium and zinc Zirconium (soluble) Boric acid Chlorides Sulfates Hexachlorophene Methenamine Phenosulfonates Urea... 

The formation of Zr(OH)5 was proposed by Sheka and Pevzner (1960) to explain an observed increase in zirconium solubility with increasing pH. Their data displayed a unit increase in solubility with a unit increase in pH, thus suggesting a solution species with a charge of -1. More recent studies (Pouchon et al, 2001 Ekberg et al, 2004 Altmaier, Neck and Fanghanel, 2008) have been unable to reproduce the behaviour observed by Sheka and Pevzner, and Pouchon et al. suggested that the observed solubility increase in the experiments of Sheka and Pevzner was likely due to contamination by carbon dioxide and the complexation of the zirconium by carbonate. As such, the formation of the Zr(OH)5" ion is not accepted by this review. 

Zirconium trifluoride [13814-22-7], ZrP, was first prepared by the fluorination of ZrH2 using a mixture of H2 and anhydrous HP at 750°C (2). It can also be prepared by the electrolysis of Zr metal in KF—NaF melts (3). Zirconium trifluoride is stable at ambient temperatures but decomposes at 300°C. It is slightly soluble in hot water and readily soluble in inorganic acids. This compound is of academic interest rather than of any industrial importance. 

Fluorozirconate Crystallization. Repeated dissolution and fractional crystallization of potassium hexafluorozirconate was the method first used to separate hafnium and zirconium (15), potassium fluorohafnate solubility being higher. This process is used in the Prinieprovsky Chemical Plant in Dnieprodzerzhinsk, Ukraine, to produce hafnium-free zirconium. Hafnium-enriched (about 6%) zirconium hydrous oxide is precipitated from the first-stage mother Hquors, and redissolved in acid to feed ion-exchange columns to obtain pure hafnium (10). 

Lead zirconate [12060-01 -4] PbZrO, mol wt 346.41, has two colorless crystal stmctures a cubic perovskite form above 230°C (Curie point) and a pseudotetragonal or orthorhombic form below 230°C. It is insoluble in water and aqueous alkaUes, but soluble in strong mineral acids. Lead zirconate is usually prepared by heating together the oxides of lead and zirconium in the proper proportion. It readily forms soHd solutions with other compounds with the ABO stmcture, such as barium zirconate or lead titanate. Mixed lead titanate-zirconates have particularly high piezoelectric properties. They are used in high power acoustic-radiating transducers, hydrophones, and specialty instmments (146). 

Uranium Purification. Subsequent uranium cycles provide additional separation from residual plutonium and fission products, particularly zirconium— niobium and mthenium (30). This is accompHshed by repeating the extraction/stripping cycle. Decontamination factors greater than 10 at losses of less than 0.1 wt % are routinely attainable. However, mthenium can exist in several valence states simultaneously and can form several nitrosyl—nitrate complexes, some for which are extracted readily by TBP. Under certain conditions, the nitrates of zirconium and niobium form soluble compounds or hydrous coUoids that compHcate the Hquid—Hquid extraction. SiUca-gel adsorption or one of the similar Hquid—soHd techniques may also be used to further purify the product streams. 

Many metal alkoxides are soluble ia the corresponding alcohols, but magnesium alkoxides are practically insoluble. Only the distillable alkoxides, like those of alumiaum, titanium, and zirconium, are soluble ia weaMy polar solvents. The double alkoxides are soluble ia alcohol K[Li(OC2Hy)2],... 

Zirconium Tetra-n-propylate. Zirconium tetra- -propoxide [23519-77-9], TunipQ ]) mol wt 327.6, is a colorless soHd, melting point, 214°C (95). The commercial product contains about 28% Zr02 and propanol it is a yellow-brown Hquid, density, 65] = 1.05 g/mL solidification point below —70°C flammable, flash point below 21°C, soluble in hydrocarbons. 

Zirconium and hafnium are separated by fractional distillation of the anhydrous tetrachlorides in a continuous molten solvent salt KCl—AlCl system at atmospheric pressure (56,57). Zirconium and hafnium tetrachlorides are soluble in KCl—AlCl without compound formation and are produced simultaneously. 

Basic zirconium carbonate reacts with sodium or ammonium carbonate solutions to give water-soluble double carbonates. The ammonium double carbonate is nominally NH4[Zr20(0H)2(C02)3]. These solutions are stable at room temperature, but upon heating they lose carbon dioxide and hydrous zirconia precipitates. 

The gels precipitated as described above are not useful in ion-exchange systems because their fine size impedes fluid flow and allows particulate entrainment. Controlled larger-sized particles of zirconium phosphate are obtained by first producing the desired particle size zirconium hydrous oxide by sol—gel techniques or by controlled precipitation of zirconium basic sulfate. These active, very slightly soluble compounds are then slurried in phosphoric acid to produce zirconium bis (monohydrogen phosphate) and subsequently sodium zirconium hydrogen phosphate pentahydrate with the desired hydrauhc characteristics (213,214). 

Although zirconium phosphate is insoluble in acids, it is easily hydrolyzed in excess caustic to give hydrous zirconium oxide. Zirconium phosphate forms soluble complexes with a large excess of zirconium oxide chloride, and therefore separation of phosphoms from zirconium oxide chloride solutions is difficult (215). 

The chemistry of hafnium has not received the same attention as that of titanium or zirconium, but it is clear that its behaviour follows that of zirconium very closely indeed with only minor differences in such properties as solubility and volatility being apparent in most of their compounds. The most important oxidation state in the chemistry of these elements is the group oxidation state of +4. This is too high to be ionic, but zirconium and hafnium, being larger, have oxides which are more basic than that of titanium and give rise to a more extensive and less-hydrolysed aqueous chemistry. In this oxidation state, particularly in the case of the dioxide and tetrachloride, titanium shows many similarities with tin which is of much the same size. A large... 

Nitrogen Nitrogen is virtually insoluble in pure sodium (10 p.p.m. at 500°C and 1 MN/m ). It is, however, quite soluble in molten lithium (2 (XX) p.p.m. at 3(X)°C and l(X)kN/m ) and can accelerate the already corrosive action of lithium, particularly on steels. Zirconium and yttrium have been used to getter nitrogen. 

Boron zirconimn chelates from ammonium hydroxide water-soluble amines sodium or potassimn zirconium and organic acid salts such as lactates, citrates, tartrates, glycolates, malates, gluconates, glycerates, and mandelates with polyols such as glycerol, erythritol, arabitol, xylitol, sorbitol, dulcitol, mannitol, inositol, monosaccharides, and disaccharides [463,464,1592,1593]... 

Syndiotactic polystyrene is a new polymeric material150 152 of industrial relevance since it shows a high melting point (270°C) and high crystallization rates.153 Syndiotactic polystyrene is a highly stereoregular polymer which can be obtained by using several soluble titanium and, to a less extent, zirconium compounds. 

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