Determination of niobium and tantalum in titanium-base alloys

Abstract

A procedure for t he determ in ation of niobium a nd tantalum in titanium-base alloys is described. The sample is dissolved in a mixture of hydrochloric and hydrofluoric acid, and oxidized with a minimum of nitric ac id. The res ulting solution is tra nsferred to a column containing a strong quatern ary amin e anion-exchange resin (Dowex-l ). Titani um and other alloying elements, except niobium and tantalum , are removed by elution with an ammonium ehloricle-hydrochlori c-h ydrofluoric acid solution. Niobium is removed b y elution with an ammonium chloride-hydrofluoric acid solution. Tantalum is collected in a separate eluate of sligh tly a cid a mmonium chloride-a mmonium fluorid e solution. Boric acid is added to complex t he fluoride, the earths acids precipitated with cupferron , ignited to the pe ntoxides, a nd ,,·eighed. IntroductjonOne o[ the difficult problems of analytical chelTl.istry ha s been the separaLion of niobium a nd tantalum from eac h other a lld from Litan ium when large amounts of titanium arc prese nt. Thi s combin ation has becom e of practiea,l importance with thc devclopmenL of ~/IST grade 821 tita nium-base allo~" containing 2 perce ll t of niobi um , ] percen t of ta ntal um, and 8 percent of aluminum .Lt has been show n [3] * that LiLa nium, ni obium, and ta lltalum can be easil.\" se parated b.\" a nion-excbange in hydroc hloric-hydrofluoric ac id combinations. Some' [lata are giv'en here for t he elu tio n behavior of t in , mol~"bdenum , vanad ium, and iron , used as alloyi ll g clements in the titanium . metal indu st r~" , and for phosphorus a tld tungsten beca use of t heir presence in naturally occurring ores or in co nce ntrates. While a question has ari sen [1] as to whether it is possible to separate thi s group of clements from niobium and tantalum, i t should be pointed out that prese nt knowledge of Lhe s ubject indicates t hat a fa irl. \-high conce ntratio n of h~"drofluoric acid is required to eliminate interfering clements and to retain tIle niobium and tantalum on the columns for subsequent separation.The ti tanium metal alloys are dissolved in a mixture of hydrochloric and hydrofluoric acid and oxidized with a minimum of nitric acid. The solut ion is tran sferred to an ion -exchange column containing the strong tetramet h~'lamine anion-exchange resin, Dowex-l. The titan ium, a nd an~T other interfering elements, are removed b.\" eluLion with an ammonium chloride-ln-droch loric-lwdrofluoric aeid solution and discarded " The niobi lim is collected in an eluate containing ammonium chloride and hydrofluoric acid. The tantalum is collec ted in a separate portion by elu tion wit h a slightl~r ac id ammonium chlorideammo nium fluoride mixture. Boric acid is added to these eluates to complex t he hydrofluoric acid , and tile ear th acids ar e t hen precipitated with cupferron. The eupferron precipitates are ignited to the pentoxides and weighed as Nb20 5 and T az0 5'The procedure requires 2 to 3 days to ca,rry to comple tion , as about 12 hr are required for the ionexchan...

Separation of hafnium from zirconium by anion exchange

“…Attach a hose-cock clamp, used to control the flow rate, to the Tygon tubing. Columns suitable for continuous operation have previously been described for both glass [ 3 ] and plastic [ 4 ] assemblies, and these are convenient to use if a number of analyses are to be performed.…”

“…G. Hevesy has written that [ 6 ] 1 “In view of the great similarity between hafnium and zirconium, it is hardly possible to separate these two elements in a single operation.” A simple one-step separation adequate for analytical work has still to be developed for hafnium-zirconium mixtures, although recent work employing ion exchange has developed suitable methods for the separation of niobium from tantalum [ 5 , 9 , 10 ] and of molybdenum from tungsten [ 2 , 9 , 10 ], and a promising start has even been made on separating the rare earths [ 12 ].…”

Aktivierungsanalytische Bestimmung von Verunreinigungen in Aluminium

“…The total retentions obtained in the presence of hydrogen bromide at 15° C are plotted as a function of scavenger concentration in Fig. 3 which also shows the curve obtained previously with bromine 22 . At large concentrations of bromine the hot atom yield of 1,2-dibromoethane should be proportional to the ratio of the concentration of bromine atoms combined as such divided by the total bromine atom concentration.…”

“…Systems containing 1,2-dibromoethane The SZILAKD-CHALMERS effect in this substance has been previously investigated 22 , but no attempt was made to study the variation in yield of the products as a function of scavenger concentration. The total retentions obtained in the presence of hydrogen bromide at 15° C are plotted as a function of scavenger concentration in Fig.…”

Anion exchange separations of metal ions in partially nonaqueous solutions

“…A prime example of the utility of this method is the complete separation of an eleven component high tempera ture alloy (63). Other alloys have also been separated by this scheme (64,65). Regardless of solvent the exchange of univalent ions may be represented by the following equation,…”