DE838604C - Process for separating the elements titanium, niobium and tantalum from one another - Google Patents

Description

Process for separating the elements titanium, niobium and tantalum from one another To the separation of the elements titanium, niobium and tantalum works, as far as known is, the technique is essentially still following procedures that in principle on Nlarignac (i865) go back. They are based for the separation of the tantalum from the titanium and niobium on the fractional crystallization of the alkali double fluoride and for the separation of titanium from niobate on fractional crystallization of sodium niobate.

The minerals containing titanium, niobium and tantalum "either earth extruded directly with hydrofluoric acid or digested with potassium bisulphate or caustic alkali, the digestion solutions are hydrolyzed and the precipitated hydrated oxides in hydrofluoric acid solved. or the minerals are chlorinated and the chlorination products (chlorides and oxychloride) hydrolyzed and dissolved in hydrofluoric acid. In all cases, the hydrofluoric acid solutions obtained from the fractional crystallization of the double fluorides subject.

The alkali double fluorides and sodium niobate are difficult to filter Precipitations and arise in solutions that are due to their hydrofluoric or strongly alkaline Character are uncomfortable to handle. In addition, the deposition of this Precipitation extremely lengthy and therefore, as well as because of the relatively high The price of the chemicals required for this is expensive. The separation measures of titanium from niobium lead z. Usually only after frequent repetitions to the satisfactory Success.

The processes described below, which are the subject of the invention, are based on the ufliicl) aridity of compounds of the elements titanium, niobium and tantalum in highly concentrated hydrochloric acid. In her solve z. B. Oxydhydrates of any kind of preparation that can be obtained z. B. dprch precipitation with NH40H, KOH or NaOH or by hydrolysis with boiling and / or introduction of CO3 or SO., As well as chlorides and oxychlorides.

The methods are therefore linked to the digestion with potassium bisulfate that has been customary up to now and / or the representation of the oxide hydrates and / or. the chlorination on.

Part I. Separation of titanium from niobium Titanium is required less often in titanium-rich mixtures of titanium and niobium compounds and is relatively simple, the separation of small amounts of titanium from niobium prepares greatest difficulty.

The inventive method is based on the fact that i. links of titanium and niobium are dissolved in highly concentrated hydrochloric acid and out of solution the titanium due to the addition of ammonium chloride and / or potassium chloride as sparingly soluble Compound (NH4) 3TiC18 or K.TiClg is precipitated while the niobium is in solution remains (see, however, Part 1I1), 2. by introducing HCI gas into the aqueous slurry of the potassium bisulfate digestion of both elements at about 0 ° and atmospheric pressure while stirring, the niobium goes into solution, while the titanium is a poorly soluble double salt (K., TiCla) is precipitated.

It is known that titanium can be deposited from solutions of TiC14 in hydrochloric acid by adding ammonium chloride and saturating the solution with HCl gas at about 0 ° as (NH4) 3TiC18 up to 0.5 mg Ti in 100 ccm of the solution ( W. Seidel and W. Fischer: Z. anorg. Allg. Chem. 247 [19411 367).

I) the dependence of the solubility of (NH4) 3TiC18 on the HCl concentration, and thus from the "temperature of the solution, and from the concentration of the solution." NH4C1 is described there and applies accordingly here as well. As an optimal condition for the most extensive precipitation of titanium is the temperature 0 °, the NH4C1 concentration 49 in iooccm and saturation of the solution with HCl.

When saturating an aqueous slurry of freshly precipitated Titanium oxide hydrate with HC1 gas while stirring, the titanium also goes into solution and can be filled up to 0.5 mg Ti in 100 ccm by adding NH.C1.

For niobium oxide hydrate, niobium pentachloride and niobium oxychloride is the solubility limit in highly concentrated hydrochloric acid i g Nb305 given in 100 ccm (G m e 1 i n - K r a u t s manual of the inorg. Chemie [1928] Vol. VI / i, pp. 221, 227, 238, 24i).

It has been found that the solubility of these compounds by Stir the solution and further introduction of HCl gas at about 0 ° to about 4 g of Nb305 can be increased in ioo ccm. Are mixtures of the compounds mentioned before both elements, the dissolvability and the speed of dissolution increase with increasing titanium content of the mixtures. In the case of oxide hydrates, the rate of dissolution is further dependent on the way they are presented and their age. With ammonia solution freshly precipitated oxide hydrates dissolve individually and in mixtures faster than that represented by hydrolysis. The representation of the Oxide hydrates found by reducing the peroxy solution of both elements with SOj gas. By introducing HCl gas directly into the solution reduced in this way, the hydrated oxides become solved again, and the titanium is after i. except for 0.5 mg Ti in 100 ccm of the solution precipitated and separated from the niobium solution by filtration. At 4 g per 100 ccm dissolved niobium oxide, the niobium oxide obtained after the Ti separation still contains o, oi2o / o Titanium. I The same separating effect is achieved when one is obtained from in other ways freshly precipitated oxide hydrates of Ti and Nb emanates, or from Ti-Nb complexes more organic Oxyacids, or of chlorides or oxychlorides.

The chlorination products can be converted into hydrochloric acid without prior hydrolysis Solution to be brought. The one for the dissolution process and the subsequent separation The high chlorine ion concentration required of the titanium is here because of the presence of the chlorine ions through the dissolved chlorides through a smaller addition of HCl gas reached.

The titanium is, as from the solutions of the oxide hydrates, according to i. severed. After adding about 4 g of NH4Cl in each case to 100 ccm of the solution, further introduction of HCl and stirring at about 0 °, the titanium falls according to the solubility of the (NH4) 3TiC18 except for 0.5 mg Ti in 100 ccm.

About the solubility of the ammonium nioboxy chloride described in the literature [(NH4) 3 NbOCIs] (Weinland and S t o r z: Z. anorg. Chemie 54 [1907] 225), the on analogous way as the ammonium titanium chloride (NH4) 3TiC18 was represented is nothing known. Given the great similarity of comparable connections between these two elements, that are related by oblique relationships in the periodic system would also be available may assume a low solubility of (NH4) 3 NhOC15. However, it was found that under i. described conditions in Ti-free niobium solutions no (NH4) 3 NbOCIs is precipitated, which accordingly increases the solubility of this compound the metals calculated is more than 5ooom times larger than that of (NH4) 3TiC1a.

(The connection described by W e i n I a n d and S t o r z (s. o.) was apparently obtained from a Ti-containing niobium solution and presumably represented an Nb-rich mixed crystal formation.) In contrast, the precipitating (NH4) 3TiC18 can to incorporate the niobium isomorphically in the form of (NH4), NbOCIs.

This fact leads to losses in the yield of niobium after separation of titanium, which is why the process becomes more uneconomical as the titanium content in the niol> oxvcl increases will. Despite this limitation, the process is a technical one Progress because it is particularly suitable for separating small amounts of titanium in front of N iob, which are extremely difficult to separate using the methods that have hitherto been used was.

a) Because of the large difference in solubility found for (NH4) 2TiC18 and des (NH4) 2 NbOCIS, the titanium is separated down to 0.012% Ti in the Nb205 in one operation; b) (las Niob can after the separation of the titanium from the highly concentrated Hydrochloric acid solution can be obtained in pure form more conveniently than by the previously customary methods. The niobium hydrate is z. B. only by diluting with \\ 'water and / or heating precipitated in a readily filterable form. In the case of separation with ammonium chloride are the compounds adsorbed by the precipitating niobium oxide hydrate volatile in the heat and therefore completely removable; c) those for the procedure The chemicals required are cheap and can be found in some cases according to known ones recovered %% - earths; d) (the procedure allows other than titanium to separate common accompanying elements of the niobium in one operation. The poor solubility the corresponding compounds in HCl saturated solution is known per se (W. Fischer, J. \\ 'ernet and 1V1. Zumbusch-1 'f i s t e r e r: Z. atiorg. Chem: 258 [1949] 157).

What is new is the possibility offered by the invention of separating these elements from the niolt individually and together with the titanium in one operation. So z. E.g. with 4 g 1 \ 'b- .05 in 100 cctn of the 11C1-saturated solution the separation of the accompanying Al as 111C13' 6 H20 except for 0.8 mg A1 / 100 ccm = 0.02% Al, Sn as ( NH4) 2 sticl, except for 0.4 mg sti / 100 cctn = o, oi% Sn, cf. '1' i as (.N li1) = "1'iC15 up to 0.5 mg Ti / 100 ccm = o, or 2 ° / o Ti.

I # olgeti (le other elements' can also be largely separated be: alkalis, alkaline earths, lanthanides, 1'ttrium, zirconium.

1) The method according to the invention can be exemplified by the following: explained: .1. 3.5 g of niobium oxide, containing 0.3% titanium oxide, are mixed with halium bisphate digested, the pulverized digestion liquid added to 75 ccrn water and solved as far as possible. In the suspension obtained is at about o ° Lind Atmospheric pressure HCl gas introduced while guiding. Over the course of et '# N a 4 hours If after saturation, ILCI gas rides the titanium as K2TiC16, while (read Niol> goes into solution. Final volume of 1_hstittg Zoo ccin.

I1. 3 g of niobium oxide, containing 0.3% titanium oxide, are digested with potassium bisulfate, the pulverized digestion mass is dissolved in about 700 ccm of water in (I keep as far as possible. The oxide hydrates are grounded out of the solution by lly (lrolysis or, better, by adding ammonia solution After filtration, the hydrated oxides are either introduced directly into 75 cc of water and dissolved by passing in 1-1C1 gas and stirring 1> e1, or better 2. in a mixture of 70 cc of 10% sulfuric acid and i ccm of 30% hydrogen peroxide dissolved. In order to achieve more soluble oxide hydrates, the peroxy-titanium-niobium solution is reduced with SO gas. Subsequent introduction of HCl gas at about 0 ° into the reduced solution removes the oxide hydrates precipitated by reduction redissolved in the course of about 3 hours with stirring; 3. to the solutions obtained according to BI and B2, about 4 g of ammonium chloride are added to each loo ccm volume and as much Am. corresponding to the Ti content monchloride more than is consumed by the precipitation as (NH4) 2TiC18. The solution is further saturated with HCl gas at about 0 ° while stirring. The finely crystalline, easily filterable precipitate is filtered off through an ice-cooled glass frit. It contains titanium as ammonium titanium chloride and isomorphically incorporated ammonium niobium oxychloride. The niobium-containing titanium precipitates obtained in each case in the separations are collected; the main amount of titanium is separated off by known processes and the product depleted in titanium is subjected again to working instruction Example B to completely separate off the titanium.

The niobium in the filtrate is diluted with water and / or Heating precipitated, filtered and burned to niobium oxide.

The yield of purified niobium oxide (0.012 0/0 Ti) is at one Concentration of 3 g of starting oxide mixture in 100 ccm of the 95% Nb205 solution at 0.3% T102 in the starting oxide, 700/0 Nb205 at 2.4% T102 in the starting oxide.

C. io g of a technical niobium concentrate of the mineral Koppit, the in addition to about 50% Nb205 essentially contains Fe2O3, Ca0, S102, A1203 and about 3% T102, are worked up analogously to Example B on pure Nb205. With bisulphate digestion S102 remains unsolved. The pulverized digestion mass is as far as possible in Dissolved water, and in the heat by introducing v, on C02 the oxide hydrates of the niob and titanium precipitated. The main amount of iron, the aluminum and some of it remains of titanium in solution. After filtration, the filtrate is discarded.

In addition to \ iob and titanium, there are essentially the Silica and undigested material.

The niobium and titanium oxide hydrates are added to about 100 cc of the mixture Dissolved sulfuric acid and hydrogen peroxide. The peroxy-niob-titanium solution is reduced according to the invention with SO, gas and, as described under B2, are the oxide hydrates are redissolved by introducing HCl gas at about 0 °.

The titanium is obtained by adding ammonium chloride (calculated amount plus about 49 NH4C1 to 100 cc of the solution) and further introduction of HCl at 0 ° and stirring precipitated.

If present, the tin at this point will have the same separating effect like titanium deposited as (NH4), SnClO. After filtration, the Hydrochloric acid Ti-free niobium solution hydrolyzed by dilution with water and / or heating. The niobium falls as an easily filterable, flaky oxyhydrate.

Any iron that has run into the HCI-saturated solution is converted by (NH4) 2TiClg built-in, possible remnants of the iron remain in the hydrolysis of the niobium hydrochloric acid solution.

The filtered niobium oxide hydrate is burned off. Yield of Nb "O, (0.04% T102): about 700/0. 1>. : \ us solutions from NbCI, and / or NhOCIg with changing Amount of titanium, the titanium is in hole-concentrated hydrochloric acid according to Hebeispiel 1; 3 separated.

11. Separation of the fineness titanium and tantalum according to the invention Mixtures of compounds of titanium and tantalum in highly concentrated hydrochloric acid can be used be solved.

By adding - "\ nimoniumchlori (I bz« -. Potassium chloride is added further introduction of HCl gas with stirring at about 0 ° the titanium as (N 1-i4), "I'iCls or K.TiC1, while (read Tautal remains in solution.

If you pass HCI gas to saturation at about o` while stirring into the aqueous solution of the potassium bisulfate digestion, the Ti and Ta in suitable proportions contains, it fails due to the presence of potassium unions (read digestion medium the titanium out as K "T1Cls, while (read Tautal remains in solution.

The strong mutual influence of the earth acids in solubility their compounds are known (O. H a 1i n and H. G i 1 1 e: Z. anorg. general Chem. ii2 [192o] 283). Thus, for example, 13th (never risulfate melts of Ta., 05-Ti02 -gemischeri clear in water if the Ti0 _, - content predominates in these mixtures.

By introducing HCl: gas into the aqueous solutions of these bisulfate digestions if at about o = the titanium is precipitated as KZTiCIs with stirring, icing the taut valley remains in solution.

There are only traces of pure tantalum oxide in highly concentrated hydrochloric acid soluble (G ni e 1 i n -Kr a u t s Handbuch der Anorg. Chemie, p. 293).

It has been found that the solubility of the TantaloxN-d] i_v (Irate with increasing Ti-content rises and that mixtures of the Avoid Oxvdhvdrate, the 5o04 T102 and more contained in Ta205, by adding HCl gas to the aqueous slurry the hydrated oxides go into solution at about 0 ° with stirring. As described in Part I, Here, too, the dissolvability and the rate of dissolution are more freshly precipitated Oxvdhydrate greater than that of the aged.

In a corresponding way, the chlorination products (chlorides) of the two elements are brought into hydrochloric acid solution. Since the subsequent Titanium separation requires the setting of the highest possible chlorine ion concentration is sufficient here, as in Part I and 1I, because of the chlorine ions present through the dissolved chlorides a lower addition of hydrogen chloride.

The hydrochloric acid solutions are converted into titanium by adding N H4C1 or KCI, as described in Part I, is precipitated while the tantalum remains in solution. An additive is required to achieve the greatest possible separation of the titanium from the tantalum of about 6 g of N H4C1 per 100 cc of the solution is required. In theory that was enough amount of NH4C1 plus calculated for the precipitation of the titanium present as (N H4) 2TiC18 about 4 g NH4C1 per 100 ccm to adjust a HCl saturated at 0 ° of NH4C1, aqueous solution.

It was impossible to predict how the tantalum would change during the precipitation of Titan behaves. In contrast to Niol>, which according to Part I of (NH4) 2TiC18 in part is incorporated isomorphically, the tantalum remains despite its great chemical similarity with the niobium completely in solution.

If the titanium is not completely covered when it is precipitated Ti residues that have become tantalum can be converted into tantalum by careful hydrolysis of the Filtrates, in which there is (las tantalum, with introduction of CO, to 0.1% Ti separated in tantalum pentoxide. .-lusl) ute to TazO ": almost ioo%.

In the case of (NH4) 2TiC18, the titanium can be removed by burning off the residue due to the presence of NH4C1 as a loose, finely divided oxide for further use to be recovered.

To justify the technical progress, refer to the information given in Part I for the all separation of titanium from N lob described advantages 11, c and d pointed out. They apply mutatis mutandis to the separation of the Titan from the Tautal. Part 11I. The separation the lenient titanium, niobium and tautal of each other. According to the invention, genniches the elements titanium, niobium and tautalum are separated from each other in a hydrochloric acid solution, that after the addition of ammonium chloride or potassium chloride and further introduction of Hydrogen chloride is precipitated together with the titanium at about 0 °, while (read Tautal remains in solution.

If you pass hydrogen chloride gas until saturation at about 0 ° Stirring in the aqueous solution of a bisulphate digestion in which the elements titanium, N lob and Tautal are present in suitable proportions to one another, then falls as a result of the absence of potassium unions due to the isomorphically incorporated niobium together as K2TiClß / K2NbOC15, during the tau valley remains in solution.

According to part 11 , the oxide hydrate mixtures of the elements titanium and tautal can be dissolved in hydrochloric acid solution if the presence of sufficient titanium in the oxide hydrate mixture makes the tantalum oxide hydrate dissolvable. This is the case when jo% T102 and more are present in the oxide mixture.

With the simultaneous presence of Nioi) in the oxide hydrate mixture the dissolution process turns out to be more complicated. Small amounts of niols affect the Not dissolvable, while the titanium content is increased with larger amounts of niobine got to. in order to dissolve the Oxydhydratgeinisches in highly concentrated hydrochloric acid respectively.

a) 13s solve z. B. Oxydhydratgemischen, in which TiO2, M) 205 and Ta205 are present in the weight ratio 2: 1: 2 or 3: i: i, in the course of about 3 hours clear, if one in the aqueous slurry of the oxide hydrates at about o ° HC1 gas is introduced with stirring.

For the \ `orzige freshly precipitated oxide hydrates, the Explanations in Part I. The same applies to the dissolvability of the chlorination products analogous to what was said in Part 1I. The separation of the elements titanium and niobium from Tantalum in the concentrated hydrochloric acid solution is based on the property of titanium after the addition of NH4C1 or KCI (NH4) 2TiC18 or K., TiCI6 zti, which compounds the niobium in the form of the corresponding oxychloride compounds to be incorporated isomorphically capital.

13s it was found that at a ratio of 2 parts Tio) 2 and more on part of Nb205 the niobium is almost completely precipitated. Here too is for the best possible separation of titanium and niobium, an additive that is approximately 50% higher of NH4C1 required (see Part 11).

1) a is the titanium content in the starting mixture of titanium compounds and tantalum (Part 1I) and titanium, niobium and tantalum (Part III) is crucial for the dissolvability of these connections and the genieiiisanie precipitability of titanium and niobium, you only need by "adding titanium compounds (read to set a suitable ratio of these elements to one another.

b) By introducing HCl gas into the watery or sludge solution a Kaliumbisulfatifscliltisses, the elements Ti, Nb and Ta in the appropriate Contains quantitative ratio to each other, the titanium is at about 0 ° with stirring precipitated together with the niobium, while the tantalum goes into solution or in 1_solution remain.

After filtration of the solutions obtained according to a or b , the tautal in the filtrate can be freed from any titanium residues by hydrolysis with the introduction of CO 2, in accordance with Part 11.

The purified tantalum pentoxide still contains i to 2% NI) and o, i to 0.5% Ti.

The residue from the filtration of a and b, the titanium and \ iob contains, is dissolved in dilute hydrochloric acid and the main amount of titanium according to known `` 'experience (expediently separated by hydrolysis). The precipitated niobium oxide hydrate may still contain a few percent titanium. After filtration, it becomes your procedure Part I subjected, in which it is purified to 0.012% Ti in N1) 205.

Because ", titanium can be extracted from the filtrate by hydrolytic precipitation, for example Precipitation with ammonia can be recovered.

Regarding the possibility of using other elements in the separation The following apply mutatis mutandis: ltisfiiliriiiigeii in Part 1. For reasons The technical progress is due to that in Part I for the separation of the titanium the advantages described by niobium. They also apply here accordingly.

According to the invention, the separation of the elements titanium, niobium and Tantalum from each other in solution saturated at about 0 ° with HCl gas at atmospheric pressure carried out.

This solvent stands out from other media in which the Separation of the elements titanium, niobium and tantalum has so far been carried out in the special in that the chemical differences are suitable for separation Connections of these elements in it are more pronounced.

Because of these great chemical differences, it is possible to find the element Titanium, the separation of which is usually sought (Part I and Part II) or titanium together with the niobium (part 11I), in each case very largely in one operation to deposit; and this is a fundamental difference from the invented one Procedure to the previous procedures, in which from the titanium-containing solutions the tantalum or niobium is precipitated in the form of strongly adsorbing precipitates, therefore, frequent repetition of the separation measures is necessary.

Claims (7)

PATENT CLAIMS: i. Process for separating the elements titanium, niobium and tantalum from one another, characterized in that solutions of these elements are expediently admixed with ammonium chloride and / or potassium chloride to saturation and are saturated with hydrogen chloride at about 0 ° with stirring and the titanium and, depending on the quantitative ratio, niobium containing sediment is separated from the niobium or optionally tantalum-containing solution. 2. Procedure for separating the elements Titanium, niobium and tantalum from one another, characterized in that by introducing of HCI gas in the aqueous solution or slurry of the potassium bisulfate digestion of compounds of these elements at about 0 ° with stirring the titanium or the titanium is deposited together with your niob in the form of poorly soluble compounds, while the niobium or tantalum remains dissolved or goes into solution. 3. Procedure according to claim i and 2, characterized in that to separate the titanium from Niobium starting solutions are used in which the titanium content is not that amount compared to niobium, in which a co-precipitation of the niobium takes place. q. procedure according to claims 1 and 2, characterized in that titanium is used to separate the elements and tantalum starting solutions are used in which the titanium content contrasts with the amount Tantalum reaches or exceeds (TiO2: Ta205> 1) at which the titanium precipitates while the tantalum remains dissolved or goes into solution. 5. Procedure according to claims 1 and 2, characterized in that titanium is used to separate the elements and niobium used from tantalum starting solutions «earths in which the titanium content is the one Nfenge compared to niobium reaches or exceeds (Ti02: Nb205> 2), in the case of titanium and niobium are precipitated together, while tautal remains dissolved or in solution goes. 6. The method according to claim i to 5, characterized in that one for adjustment a high concentration of chlorine ions in concentrated solutions of the chlorides and / or Oxychloride of the elements titanium, niobium and tantalum runs out and therefore less HC1 gas needs to add. 7. The method according to claim i to 6, characterized in that that in addition to titanium or titanium and niobium, other elements such. B. aluminum and tin, be separated, those in HCl-saturated solution or HCl-KCl-saturated or HCl-NH4C1-saturated Solution form poorly soluble compounds.