Tantalum columns

Stainless-steel (type 316) columns do not have these disadvantages of copper, aluminium and iron tubes and are very suitable. In most HPLC applications, 316 stainless-steel column tubes can be used without difficulty. When the chemical inertness is insufficient, the 316 stainless-steel column can be replaced with the more expensive but more inert tantalum column tubes (Siemens). When very strongly acidic mobile phases have to be used, 316 stainless-steel columns are less suitable. For such instances, sometimes home-made titanium columns, including titanium terminators and injection systems, have been applied successfully. ... 

Acid corrosion presents a problem in isopropyl alcohol factories. Steel (qv) is a satisfactory material of constmction for tanks, lines, and columns where concentrated (>65 wt%) acid and moderate (<60° C) temperatures are employed. For dilute acid and higher temperatures, however, stainless steel, tantalum, HasteUoy, and the like are required for corrosion resistance and to ensure product purity (65). 

The reaction temperature of 500—600°C is much lower than that required for the reductive chlorination. The volatile chlorides evolve from the molten salt bath. The boiling points of NbCl, TaCl, and WOCl He between 228 and 248°C. These compounds must therefore be separated by means of a distillation column. The chlorination of ferroalloys produces very pure tantalum pentachloride in toimage quantities. The TaCl contains less than 5 )J.g Nb/g Ta, and other metallic impurities are only amount to 1—2 lg/g Ta. 

Carbon steel, stainless steel, aluminum, tantalum, titanium, and zirconium are used for both loose-fill and structured metal packing. All have reportedly been involved in packing fire incidents. Titanium, in particular, has been involved in a number of column fires. 

Selective vaporization and deposition are performed in radiofrequency-heated tantalum distillation columns (Fig. 4). The... 

Fig. 4. Tantalum distillation columns and appropriate temperatures (K) for the preparation-purification of Am and Cm metals.

Preparation of Niobium (Tantalum) Chloride and Purification from Iron Impurities. Assemble an apparatus as shown in Fig. 124. Place activated carbon preliminarily dried in vacuum during two hours at 200-250 Cinto section III of the reactor. Mix 2 g of niobium (tantalum) and 0.5 g of iron in a porcelain boat and place them in section I. Fill columns 5 and 6 with a mixture of glass wool and phosphoric anhydride, and fill wash bottle 7 with sulphuric acid. 

An 8-mm x 1-m jacketed column packed with a coiled tantalum wire was used by the submitters. The checkers used a Vigreux column of similar size. 

The checkers employed a Podbielniak column, 0.8 x 125 cm., with tantalum wire spiral and partial reflux head.3... 

In experiments at the UNILAC accelerator at GSI, Darmstadt, the tantalum isotopes 168 170Ta were transported by the He(KCl) gas-jet and deposited on a polyethylene frit in ARCA II. The dissolution of the collected tantalum activity from the frit was investigated as a function of the a-HiB concentration. Because of the smaller column size in ARCA II (1.6x8 mm) which might cause an earlier breakthrough of the tetravalent and trivalent metal ions it was desirable to decrease the a-HiB concentration. Even with 34 pL of 0.025 M a-HiB, dissolution of >75% of the tantalum activity was achieved in 2 s. The time required for the complete elution of Ta from the column was about 4 s. Similar experiments performed at the Mainz TRIGA reactor with "mNb confirm this result as shown in Figure 14. 

The calibrated, glass feed tank has a diameter of 102 mm and a capacity of 4.5 L. Solutions can be added to the tank via two routes first, vacuum can be applied to the tank to motivate transfer of adjusted feed solution from the feed adjustment evaporator and secondly, pressurized transfer of solution can be made from the eluent addition tank. A tantalum diaphragm pump is used to transfer solutions from the feed tank to the top of the ion exchange column. Flow rates are controlled by cycling vacuum and pressure against the diaphragm at a selected frequency a discharge pressure of up to 200 kPa can be achieved. 

Make a table to show the differences and similarities between tantalum and cesium. For each metal, add a column to describe how its different properties make it useful for specific applications. 

Carlson and Nielsen (C3) described the pilot and full-scale plant separation of an ore containing more than 30% combined columbium and tantalum oxide using a sulfuric-hydrofluoric acid leach and methyl isobutyl ketone (MIBK) as solvent in pulsed columns. The —200 mesh columbite-tantalite ore was digested with 70% HF until the combined (Ca + Ta)20s in the leach liquid reached 3 Ib/gal at which time it was diluted to 15N free acid and clarified by filtration. This solution was contacted countercurrently in the pulsed column where Ta and Cb were extracted by MIBK. Columbium was stripped from the organic with demineralized water which diluted the free acid in the solvent, making possible the transfer of all the Cb the Ta-loaded solvent was then stripped with demineralized water causing the transfer of Ta to the aqueous phase. The oxides were then precipitated with 28% ammonium hydroxide solution. Conversion to the respective oxides was by calcination of the precipitates. 

Niobium and tantalum can also be separated by solvent extraction (p. 572) Nb is extracted almost quantitatively from HCl solution by methyldioctyl-amine in xylene while Ta remains in the acid. (Leddicotte and Moore, 1952). Chromatographic methods (p. 570) are also possible. Thus Mercer and Williams (1952) separated Nb and Hf from ores containing Ti and other metals. The fluorides were adsorbed on paper pulp elution with methyl ethyl ketone saturated with water extracted the tantalum equilibration of the column with a 1% solution of HF in the ketone arrested the movement of Ti, Zr... 

The most simple design of such a column is shown in figure 4. The column wall and the sieve plates are made of titanium and work as cathodes. The central rod made of platinized tantalum and separated electrically from the sieve plates by means of ceramic rings, serves as the anode. Additional cylindrical metal sheets... 

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