Potassium fluorozirconate

High purity hexafluorozirconic acid and its salts are produced by Advance Research Chemicals of the United States, and Akita and Moritta of Japan. The technical-grade green-colored material is suppHed by Cabot Corp. of the United States. In 1993, the U.S. market for fluorozirconic acid was about 250,000 kg/yr the world market was less than 500,000 kg/yr. A principal part of this production is consumed by the wool, garment, and upholstery industries. The 1993 price varied between 2.4 to 6.6/kg depending on the quaUty and quantity required. Potassium fluorozirconate [16923-95-8], K ZrF, is commercially important the world market is about 750,000 kg/yr. The most important appHcation is as a fire-retardant material in the wool (qv) industry, for the manufacture of garments, upholstery for aeroplane industry, and children s clothes (see Flame retardants). The 1993 unit price was between 5.0 and 6.6/kg. 

Reduction. Brezehus attempted the first reduction of zirconium in 1824 by the reaction of sodium with potassium fluorozirconate. However, the first pure ductile metal was made in 1925 by the iodide thermal-dissociation method. The successful commercial production of pure ductile zirconium via the magnesium reduction of zirconium tetrachloride vapor in an inert gas atmosphere was the result of the intense research efforts of KroH and... 

Aflammit ZR Dipotassium hexafluorozirconate(2-) Dipotassium zirconium hexafluoride EINECS 240-985-6 HSDB 2019 NSC 310011 Potassium fluorozirconate Potassium fluorozirconate (K2ZrF6) Potassium hexafluorozirconate Potassium zirconifluoride Potassium zirconium fluoride Potassium zirconium hexafluoride Zirconate(2-), hexafluoro-, dipotassium Zirconium potassium fluoride, Flameprooflng agent used in wool processing. Also used in manufacture of zirconium. Solid slightly soluble in cold H2O, Thor Chemicals (UK) Ltd. 

Reid et al. (454) reinvestigated the synthesis of the zirconium and hafnium borohydrides. The reaction of diborane with zirconium tetrachloride dissolved in tetrahydrofuran (THE) does not give a boron-containing product, whereas the reaction of diborane with an ether solution of zirconium tetraethoxide gives the desired metal borohydx ide although it is difficult to separate from the borate ester coproduct. The reaction of Katz (246) was run with potassium fluorozirconate in preference to the sodium salt because the potassium salt reacted more readily,... 

Potassium fluorozirconate. See Zirconium potassium hexafluoride Potassium fluosilicate CAS 16871-90-2... 

Synonyms Dipotassium hexafluorozirconate Potassium fluorozirconate Potassium fluozirconate Potassium zirconifluoride Potassium zirconium fluoride Potassium zirconium hexafluoride Zirconium potassium fluoride Definition Zirconium potassium fluoride Empirical FsK2Zr Formula K2ZrFe... 

A process is operated in the U.S.S.R., on a production scale for the breakdown of zircon by sintering with potassium silicofluoride. The principal reason for the employment of this route is the fact that the product potassium fluorozirconate, is suitable for feeding directly to the Russian fractional crystallization purification process. This removes the 1-5 to 2-5 per cent of hafnium which originates in the zircon mineral. 

The sodium reduction of titanium tetrachloride was actually carried out as early as 1939 in Germany, and about 670 kg was produced by the Deutsche Gold and Silber Scheideanstalt, during the 1939-45 war. The process, now obsolete, involved reduction in a molten bath of 50 per cent sodium chloride and 50 per cent potassium chloride at 800°C in an atmos phere of hydrogen. The reactors consisted of expendable welded sheet-iron cylindrical vessels, 50 cm diameter by 70 cm deep and 2 mm thick. These rested loosely in a stout iron crucible, fitted into a gas-fired furnace. A portable stirrer was used to agitate the reactor contents. Approximately 20 kg batches of titanium were reduced by distilling 85 kg of titanium tetrachloride at a controlled rate into a melt of 15 kg sodium chloride and 15 kg of potassium chloride, covered with a layer of 46 kg of molten sodium. The titanium sank to the bottom of the molten salts, and at the end of the reaction was recovered from the crushed solidified melt by leaching with dilute hydrochloric acid, in a ceramic-lined vessel. It was finally washed in water and dried at a moderate temperature. The same plant was also used for the production of zirconium metal by the sodium reduction of potassium fluorozirconate (KaZrF ]. 

An electrolysis run is started by heating the cell to 830-50°C and adding a charge of 170 lb of pure, dry sodium chloride. When molten, 50 lb of vacuum-dried potassium fluorozirconate is added. Pre-electrolysis, to remove impurities onto a graphite cathode, as used in the smaller cells, is... 

The metal zirconium is very strongly bound to oxygen in the oxide ZrOj. Reduction with carbon has no prospect of success. However, in 1824, 35 years after Klaproth s discovery, BerzeHus was able to prepare potassium fluorozirconate K2ZrFg and reduce it with potassium metal The product was a black metal powder Berzelius reported that it was impossible to compact the powder to a metal of conventional appearance so the product was obviously impure. In the following years many unsuccessful attempts were made to isolate pure ductile zirconium metal. 

Zirconium, atomic number 40 and atomic weight 91.22, was identified by the German chemist, Klaproth, in 1789. However, the metal itself was not isolated imtil 1824, when Berzelius produced a brittle, impure metal powder by the reduction of potassium fluorozirconate with potassium. One himdred years later, van Arkel and de Boer developed the iodide decomposition process to make a pure, ductile metal in Einhoven, Holland. The "iodide crystal bar" process continues to be used today as a method of purifying titanium, zirconium, and hafnium, even though it is slow and expensive. 

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). 

Because K2HfF6 is —1.7 times more soluble in water than K2ZrF6,528 zirconium and hafnium can be separated by fractional crystallization of the hexafluorometallates. This approach is used on an industrial scale in the USSR.286 Conductance measurements on aqueous solutions of M2MF6 (M = K, Rb, or Cs) indicate very little hydrolysis of the [MF6]2- ions.529 Alkaline hydrolysis of potassium and ammonium fluorozirconates yields crystalline M ZrF3(0H)2-H20 complexes, which are easily dehydrated to M ZrF3(OH)2. 

A proportion of potassium chloride is also present in the reaction mixture and this assists the reaction to go to completion. The efficiency of conversion of the zirconium to fluorozirconate is in fact about 97 to 99 per cent. 

Potassium Hexafluorozirconate [16923-95-8]. This water-soluble com-poimd is a flame retardant for wool by the Zirpro process. Applied in combination with formic acid and citric acid, the fluorozirconate exhausts onto wool and after mild heating, provides a fairly wash-dimable flame-retardant finish. Wool upholstery for aircraft makes use of this treatment (19). 

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