DE1018037B - Process for felling tantalum or. Niobium compounds from ketonic solutions - Google Patents

Description

Process for the case of tantalum or. Niobium compounds from ketonic Solutions It is known to use tantalum or niobium compounds from ores, concentrates, Slags and metallurgical intermediates can be obtained by using these substances can be digested with hydrofluoric acid, which removes the metals as fluorides go into solution. However, as is also known, the digestion can also be carried out by means of chlorine take place. In the case of oxidic substances, reducing conditions must be observed at the same time. The resulting chlorides of tantalum and niobium as well as the accompanying elements are subsequently dissolved in strong hydrochloric acid. From such aqueous acidic solutions the tantalum or niobium fluorides and / or chlorides can be used in a known manner extract fractionated using ketones. From the separated ketone solution must then the tantalum and / or niobium compounds are precipitated in a filterable form will. To this end, it has been proposed to use tantalum or niobium with the aid of alkali metal hydroxides or carbonates, but especially to precipitate with ammonia. Tantalum and niobium fall in this case as hydrated oxides, which produce an extremely voluminous precipitate represent, which is very poor from the liquid, z. B. by filtration, can be separated. In addition, the voluminous precipitate is difficult to wash off and includes ketone. Since the ketone is a technical process for economic reasons Reasons must be reused as an extractant in the cycle, means this results in a considerable loss of organic extractants. The ketone is taking especially when using Ammoniumhy droxyd ammonia, so that it is advantageous is to regenerate it before returning it to the process. Here, however, occur again greater ketone losses. A wide variety of ketones can be used, however, methyl isobutyl ketone and methyl ethyl ketone are particularly suitable.

When neutralizing the organic phase with the above Precipitants also have a considerable heat of neutralization, which is necessary makes to carry out the precipitation with cooling, on the one hand, under certain circumstances To protect equipment made in heat-sensitive plastic, on the other hand but also to switch off evaporation losses.

The invention has set itself the goal of the disadvantages of this known avoid the precipitation process associated with neutralization and reduce the tantalum or niobium compounds to be precipitated in an easily filterable form. According to the invention the process consists in separating the tantalum or niobium compounds from their fluorine or Solutions containing hydrogen chloride by adding potassium salts to the ketonic To precipitate the solution immediately in the form of the double salts. It can be of the most varied Potassium salts get used, so z. B. Potash Chloride. However, it has Potassium fluoride has proven to be advantageous, especially in the case of fluoride-containing, ketonic solutions to use as this. prevents foreign anions from being carried into the ketone will. Potassium bifluoride is particularly suitable. It is known per se that in aqueous solution hydrofluoric acid tantalum and niobium compounds by adding potassium fluoride can be converted into the corresponding double salts. A quantitative turnover does not take place. According to the invention, however, in ketonic solution worked, which is practically anhydrous. By adding, in particular the potassium fluoride, potassium-tantalum-fluorine or potassium-niobium-fluorine compounds are formed. These double salts precipitate in a finely crystalline, easily filterable form. The precipitation takes place without significant heating so that ketone evaporation losses do not occur and heat-sensitive Plastics for the apparatus can be used. The residual hydrofluoric acid content in contrast to the known process, in the ketone is not destroyed by neutralization, it remains in the circuit, so that the consumption of hydrofluoric acid is reduced.

The precipitated crystal pulp can already be removed from the ketone phase largely separate by decanting, so that during the filtration no longer the all of the ketone must pass through the filter, as is the result of a hydroxide precipitation the poor deductibility can very easily be required. Through this will a considerable gain in time is achieved, and the required Nutschenraum can be considerable be smaller. Furthermore, washing out of the filtration residue is common unnecessary.

The double salts fall in a form that is particularly favorable to filtration from the organic solution when the potassium bifluoride is introduced as a solid salt will. This applies in particular to the precipitation of the niobium double salt.

To accelerate the precipitation reaction, which may occur in the Tantalum precipitation has been shown to require the presence of some water can be appropriate. In no case should the amount of water be around 3% of the total amount exceed. It is known that potassium tantalum fluoride is difficult in water, the potassium niobium fluoride is much more soluble, so this fact makes for separation of the two elements has been used. However, it was not foreseeable that the addition of potassium salts to ketonic solutions of tantalum or Job which is practical causes quantitative precipitation of the corresponding potassium double halides. A heat build-up does not occur in this precipitation process. Furthermore, it was not foreseeable that one a tantalum and / or niobium double compound is obtained by this method of precipitation, which can be converted into pure double halides by simple recrystallization. In particular, the double fluorides of Job and Tantalum are important intermediate stages in the metallurgy of tantalum and niobium.

Some preferred embodiments of the method according to the invention are shown: Examples 1. 2.3 m3 hydrofluoric acid-tantalum-niobium solution, which through Dissolving a tantalum-niobium-containing precursor in hydrofluoric acid was prepared about 60g / 1 tantalum and about 57 g / 1 niobium, furthermore the impurities titanium, iron, Containing tin, phosphorus, sulfur, was with llethylisobutyllceton after per se well-known principle extracted in the circular process, whereby the tantalum in the ketonic Solution, the niobium goes into the aqueous solution. A total of 25 extractions were carried out, each with 2001 ketone.

The tantalum was precipitated from the ketonic solution from the 2001 ketonic solution obtained by adding 6 kg each of solid potassium bifluoride with vigorous stirring. The precipitation of potassium tantalum fluoride takes place within 2 hours in the absence of water, whereas it was complete within 1/2 hour after addition of 51% of water. The supernatant, now tantalum-free, acidic ketone was returned to the process and the precipitated, crude salt was filtered off from the adhering ketone, which was about 5 liters, on a Hutsche. A total of 165 kg of crude potassium tantalum fluoride were obtained in this way, from which pure salt with the following contents was obtained by simple recrystallization: Ta = 45.8% / a Nb = 0.02% Ti = 0.029 / o Wo3 = 0.03% Fe = Traces F = 33.90% Ca0 = 0.075% Si 02 = 0.010 / 0 K = 19.8 0 / 0-2 . Using a method not previously known, it is possible to extract the niobium from solid niobium-containing oxide hydrate mixtures with hydrofluoric ketone . Thus, 35 kg of a dried oxide hydrate mixture with IN- b2 OS = 17.09 / o Ta205 = 1.69 / o 7i 0 "= 13.3 0/0 WO3 = 2.0% were extracted with hydrofluoric acid ketone by removing the solid product in 1501 methyl isobutyl ketone, to which 251 70% hydrofluoric acid was added. After stirring for one hour, the organic phase was siphoned off, the residue collected on a hatch and filtered off. The filtrate was combined with the siphoned off main amount of ketone Addition of 12 kg of solid potassium bifluoride with vigorous stirring. Potassium niobium fluoride precipitated. The precipitation was finished after 1 / z hour. The precipitate settled out immediately and the ketone phase could be drawn off for further extractions. The precipitate was placed on the Hutsche and sucked off Moist crystal pulp weighed 25 kg and, in the dried state, contained: 1 \ 7b205 = 40.0 0/0 Ta, "0S = 1.2 9/0 Ti 02 = 0.05 0 / a w03 = traces. A potassium niobium fluoride was obtained by recrystallization, which contained 0.3 part of titanium and 0.3 part of tantalum per 100 parts of niobium.

3. In the case of an extraction of the starting material described in Example 2, with exactly the same extraction process, was used for the precipitation of halinmrliobfluorides 12 kg of potassium chloride were used from the organic phase in place of the potassium bifluoride. The precipitation proceeded analogously to Example 2. The resulting potassium niobium fluoride was recrystallized, and the crystallized salt showed the same composition, as indicated under Example 2.

Claims (4)

PATENT CLAIMS: 1. Process for felling tantalum or niobium compounds from their ketonic solutions containing fluorine and / or hydrogen chloride, thereby characterized in that the tantalum is obtained by adding potassium salts to the ketonic solution or Job can be felled in the form of their double salts. 2. The method according to claim 1, characterized in that potassium fluoride, in particular potassium bifluoride, is added will. 3. The method according to claim 1 and 2, characterized in that the potassium bifluoride is introduced into the solution as a solid salt. Considered publications: K. A. Hofmann, "Textbook of Inorganic Chemistry", 2nd edition, Vieweg-Braunschweig, 1919, p. 570; Kirk-Othmer, "Encyclopedia of Chemical Technology," Vol. 4, The Interscience Encyclopedia, Inc., New York, 1949, p. 317.