Zirconium production

Total hafnium available worldwide from nuclear zirconium production is estimated to be 130 metric tons annually. The annual usage, in all forms, is about 85 t. The balance is held in inventory in stable intermediate form such as oxide by the producers Teledyne Wah. Chang (Albany, Oregon) and Western Zirconium in the United States Ce2us in France Prinieprovsky Chemical Plant in Ukraine and Chepetsky Mechanical Plant in Russia (crystal bar). 

In the chemical process industry molybdenum has found use as washers and bolts to patch glass-lined vessels used in sulphuric acid and acid environments where nascent hydrogen is produced. Molybdenum thermocouples and valves have also been used in sulphuric acid applications, and molybdenum alloys have been used as reactor linings in plant used for the production of n-butyl chloride by reactions involving hydrochloric and sulphuric acids at temperatures in excess of 170°C. Miscellaneous applications where molybdenum has been used include the liquid phase Zircex hydrochlorination process, the Van Arkel Iodide process for zirconium production and the Metal Hydrides process for the production of super-pure thorium from thorium iodide. 

Pal and Kapoor74 have studied the reactions of isopropoxides of aluminum, titanium and zirconium with benzo- and phenylaceto-hydroxamic adds in anhydrous benzene. Solid products of the types Al(OPr )3 L and M(OPri)4 L (where M = Ti or Zr and L is the hydroxamic acid) have been isolated all the aluminum and zirconium products are white in colour whereas titanium ones are yellow. The mixed isopropoxide hydroxamates interchange their isopropoxy group with r-but-oxy groups, yielding r-butoxide products. 

ARIDRY SS-80 has been developed as a specialty water repellent to be used where many other hand builders and auxiliaries are used without sacrificing a high degree of water repellency. ARIDRY SS-80 is a one-package zirconium product that incorporates a blend of emulsifiers that lend an inherent uniqueness to the product. ARIDRY SS-80 can be applied to many types of fabrics but is particularly effective on rayon linings. 

Shelton SM (1995) Zirconium production method. In Lustman B and Kerze FJr (eds) The metallurgy of zirconium. McGraw-Hill, New York, pp59-101... 

Zirconium purification and conversion to zirconium dioxide. The zirconium-product stream leaving the HCNS recovery column D of Fig. 7.6 contained most of the metal impurities in the ZrCl4 feed other than hafnium. Purified zirconium was obtained by precipitating Zr(OH)4 at a pH low enough to prevent precipitation of other metal hydroxides. The precipitation procedure used by the Bureau of Mines was as follows. Zirconium content of the raffinate was diluted to 19 g/liter. To every cubic meter of diluted raffinate were added 5.7 liters of concentrated 33 N sulfuric acid, followed by sufficient 28% ammonium hydroxide to bring the pH to 1.2 to... 

Figure 7.9 Megy process for producing reactor-grade zirconium from natural sodium fluozircon-ate. Material quantities in moles. Basis, 1 mol zirconium product.-----salt ------ metal.

The salt at point 5 is recycled to step A of a later batch. The zinc solvent at point 6 is distilled from the zirconium product and recycled to a later batch at point 2. 

The reduction of zirconium tetrachloride in a carrier salt with sodium as a reducing agent may be examined next. Again, as described before, complete deoxidation of the bath before reduction is the essential condition for success, if ductile metal is wanted. Zirconium tetrachloride is soluble in sodium chloride or potassium chloride (48) and a salt with about 25% zirconium tetrachloride can be melted without excessive zirconium chloride losses. Such a bath can even be obtained from powdery commercial zirconium silicide and iron dichloride, which react when heated and deliver a stream of zirconium tetrachloride, contaminated with some titanium tetrachloride and silicon tetrachloride. The gas so produced can be condensed in a fused salt bath such as potassium chloride-sodium chloride, in which only the zirconium tetrachloride dissolves (47), To obtain a low oxide metal after reduction with sodium, the conditions for fluo salt deoxidation must be observed. This process of zirconium production has no special interest, except for obtaining powder for getter purposes. A carrier salt, which might introduce oxide, is not wanted, as the reaction itself liberates sodium chloride. 

Figure 7-70. Zirconium production by direct decomposition of its tetrachloride (ZrC ) in atmospheric-pressure thermal plasma. Composition of products ...

The main feed solvent strip flow ratios are 1 2 5 0 25, but the extraction and stripping sections are separate extractors and the aqueous strip solution is returned to the feed vessel rather than to the point of entry of the feed. This means in practice that the strip volume is already included in the main feed volume, to bring the zirconium feed concentration to 100 g/1. The zirconium product concentration is about 75 g/1. and it still contains an excess of hydrochloric acid, with only a trace of thiocyanic acid. 13... 

A similar hexone-thiocyanate process has been operated in the U.S.A., firstly by the Northwest Electrodevelopment Laboratories at Albany since 1952 and the Carborundum Metals Corporation plant near Akron, New York, since 1953. They use packed and unpacked columns and the difficulties associated with polymerization of thiocyanic acid were alleviated by using a solvent consisting of 80 per cent hexone and 20 per cent butyl acetate instead of solely hexone. > The zirconium product is precipitated as the acid sulphate, phthalate or salicylate, and a certain additional degree of purification is obtained at this stage. A typical analysis of pure zirconium oxide after hexone-thiocyanate extraction and salicylate precipitation is as follows ... 

Any of these processes can be adjusted to a zirconium product containing 0-01 per cent of hafnium or less, although the normal French product is accepted at about 0-02 per cent to 0-03 per cent. ... 

Fig. 7.3. Zirconium Electrolysis cell (Shelton, S. M., Zirconium Production Methods, Metallurgy of Zirconium, McGraw-Hill. U.S.A.E.C. Copyright).

Valves of the conventional packed type are unsuitable for vacuum work. Bellows sealed valves are subject to corrosion and failure of the bellows, and diaphragm valves have also proved unsuccessful. A special valve designed for the purpose by the Westinghouse Electric Corporation, shown in Fig. 8.3, has proved reasonably satisfactory on zirconium production units. 

Zirconium production with the Kroll process is carried out by the following steps [19.4] ... 

NFPA 482, Processing, Handling and Storage of Zirconium Production... 

Mineral chlorination, precious metals, titanium and zirconium production (Kroll process) chlorinator various 300-900 °C Cl2-corrosion... 

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