RU2241677C1 - Method of processing solution containing fluorotitanic acid and impurity minerals - Google Patents

Abstract

FIELD: inorganic compounds technology.

SUBSTANCE: invention relates to processing solutions containing fluorotitanic acid and impurities, in particular in preparation of titanium dioxide pigment, high-purity titanium dioxide, and others. Solution containing fluorotitanic acid and impurity minerals is concentrated to content of fluorotitanic acid (on conversion to TiO₂) not higher than 800 kg/m³ and mixed with organic solvent in the form of oxygen-containing extractant, namely aliphatic C₇-C₁₂-alcohols, preferably 2-ethylhexanol, 1-octanol, 2-octanol, or their mixtures. Resulting mixture is subjected to 3-6-fold extraction until content of fluorotitanic acid in raffinate achieves 200-300 kg/m³ (as TiO₂). Ratio of organic to aqueous phase (2-5):1. These phases are separated from each other to give fluorotitanic acid extract and raffinate. Part of the latter is returned into concentration operation. Acid is the re-extracted 3-5 times with aqueous re-extractant at organic-to-aqueous phase ratio (1-5):1 to give re-extract in the form of purified fluorotitanic acid solution. Aqueous re-extractant can be purified water, initial solution evaporation condensate, or solution of purified fluorotitanic acid. Regenerated organic phase is returned into extraction stage.

EFFECT: increased fluorotitanic acid purification degree.

9 cl, 3 dwg

Description

The invention relates to hydrometallurgy and can be used in the processing of industrial solutions containing fluorotitanic acid and impurity elements, in particular in the preparation of pigment titanium dioxide, high-purity titanium dioxide used in the electronics industry for the production of ultrahigh-quality titanates and titanyls, photosensitive titanium dioxide used for color copying etc.

Upon receipt of titanium dioxide by pyrolysis of fluorotitanic acid containing limiting impurity elements, preliminary cleaning of the fluorotitanic acid solution from impurities is necessary. The purification by known methods, for example by precipitation or extraction of impurity elements, electrolysis, freezing, etc., does not allow to obtain fluorotitanic acid of the required quality.

A known method of processing a solution containing fluorotitanic acid and impurity elements (see RF patent No. 2149912, IPC ⁷ C 22 B 33/24, 34/12, 3/06, 3/26, 2000), including nitrogen hydrofluoride opening of loparite concentrate to obtain a solution of fluorobiobic, fluorotantalic and fluorotitanic acids, extraction extraction of tantalum and niobium using octanol-1 as an extractant, in which fluorobiobic and fluorotantalic acids are transferred into the organic phase (extract), and fluorotitanoic acid remains in the aqueous phase (raffinate). Next, the raffinate is evaporated 1.5-2 times to a content of 350-400 kg / m ³ according to TiO ₂ and high-temperature pyrolysis of the fluorotitanic solution to produce pigment titanium dioxide and regenerated hydrofluoric acid.

In this method, the processed solution has a complex impurity composition, which does not allow to ensure high purity of fluorotitanic acid extracted into the raffinate. Therefore, the resulting solution of fluorotitanic acid can only be used to obtain pigment titanium dioxide. In the case of using a raw material of a different composition of impurities, additional purification of a solution of fluorotitanoic acid, which is sent to pyrolysis, may be required, both for obtaining pigment titanium dioxide and titanium dioxide used in the electronic industry.

There is also a method of processing a solution containing fluorotitanic acid and impurity elements (see Masloboeva S.M., Sklokin L.I., Budnikova N.N. Extraction of titanium from fluoride solutions for processing loparite concentrate // New processes in the metallurgy of non-ferrous, rare and noble metals: Collection of scientific papers / Kola Scientific Center of the Russian Academy of Sciences, Apatity, 2001. - P.60-62), including concentration of the initial solution by evaporation to the content, kg / m ³ : TiO ₂ - 300, HF - 410 , Fe - 2,0, Na ₂ O - 0,56, Al ₂ O ₃ - 0,054, Cr ₂ O ₃ - 0,003, MnO - 0,006 followed by extraction ftortitanov th acid with an organic solvent as tributyl phosphate (TBP) at 10 stages at a ratio of organic and aqueous phases O: B = 4 to transfer to the organic phase the main part of the acid, and the aqueous phase - the main part of the impurity elements. For a more complete extraction of fluorotitanic acid, the initial solution can be evaporated to a content of TiO ₂ - 520 kg / m ³ . Reextraction is carried out in 4 steps with a ratio of organic and aqueous phases O: B = 3 with the direction of the regenerated organic phase to the extraction operation. As a stripping agent, a portion of the stripping diluted with water to an HF content of 40 kg / m ^{3 is used} . The obtained strips in the form of solutions of purified fluorotitanic acid have the following composition, kg / m ³ : TiO ₂ 100-120; HF 150-210; Fe 0.007; Na 0.01; Nb <0.001; Al 0.005; Cr 0,0002; Mn 0.0002. The resulting raffinate is sent to the operation of evaporation of the initial solution. After extraction, the extract of fluorotitanic acid can be washed, and the spent washing solution is combined with the raffinate and also sent to the evaporation operation. The extractant used (TBP) is periodically regenerated by treating it with a solution of sodium carbonate and saturation with hydrofluoric acid.

This method is characterized by a relatively high degree of acid extraction and a low content of impurity elements in it, but not sufficiently high (100-120 kg / m ³ in terms of TiO ₂ ) concentration of fluorotitanic acid in the reextract. The extractant used in the method is TBP, which belongs to the class of organophosphorus compounds, which, during the extraction of fluorotitanic acid, undergo partial hydrolysis with the formation of mono-, dialkylphosphoric acids. This leads to the destruction of the extractant and the appearance in the aqueous phase of an undesirable impurity of inorganic phosphorus compounds. In addition, TBP has a density close to the density of water, which leads to delayed phase separation, requires a large number of steps for stripping, eliminates the possibility of stripping with water and requires additional operations for regeneration of the extractant.

The present invention is directed to solving the problem of obtaining a concentrated (up to 500 kg / m ³ in TiO ₂ ) solution of fluorotitanic acid for its subsequent pyrolysis using aliphatic alcohols as an extractant while ensuring a high degree of fluorotitanoic acid extraction and its purification, regardless of the composition of impurity elements, as well as the optimization of material flows and equipment used.

The technical result is achieved by the fact that in the method of processing a solution containing fluorotitanic acid and impurity elements, including concentration of the initial solution, mixing the concentrated solution with an organic solvent in the form of aliphatic alcohols, extraction of fluorotitanic acid with the main part of fluorotitanic acid being converted into the organic phase and into the aqueous phase phase - the main part of the impurity elements, the separation of the organic and aqueous phases with the formation of an extract of fluorotitanic acid and raffinate, return Asti raffinate in the concentration step, stripping acid aqueous reextractants to obtain reextract as a solution of purified fluorotitanic acid and return the regenerated organic phase extraction, according to the invention the concentration of the starting solution is carried out until it contained fluorotitanic acid is not more than 800 kg / m ³ on TiO _2, aliphatic alcohols are used as a neutral oxygen-containing extractant, extraction is carried out in 3-6 steps until the fluorotitanic acid content in the raffinate is 200-300 kg / m ³ according to TiO ₂ , and reextraction is carried out at 3-5 steps with a ratio of organic and aqueous phases of 1-5: 1.

The technical result is also achieved by using an initial solution containing 50-300 kg / m fluorotitanic acid in terms of TiO ₂ , and as impurity elements at least one of the elements: Al, Ca, Cl, Cr, Fe, Mg, Mn, Na, Nb, Si, Ta, Ti, V, Zn, Zr with a total oxide content of impurity elements up to 50 kg / m ³ .

The technical result is also achieved by the fact that the concentration of the initial solution is carried out by evaporation to the content of fluorotitanic acid 500-800 kg / m ³ in TiO ₂ , after which the solution is cooled to a temperature of 15-30 ° C.

The technical result is achieved by the fact that aliphatic alcohols use alcohols with the number of carbon atoms C ₇ -C ₁₂ , mainly 2-ethylhexanol, octanol-1, octanol-2, or mixtures thereof.

The achievement of the technical result is directed to the fact that extraction is carried out with a ratio of organic and aqueous phases of 2-5: 1.

The technical result is also directed to the fact that purified water, condensate from evaporation of the initial solution or a solution of purified fluorotitanic acid are used as an aqueous stripping agent.

To achieve a technical result, it is also directed that reextraction is carried out to a content of fluorotitanic acid in the reextract of not more than 500 kg / m ³ according to TiO ₂ .

To achieve a technical result, it is also directed that up to 80 vol.% Of raffinate is returned to the concentration operation.

The achievement of the task is also facilitated by the fact that after the extraction, the extract is washed with purified water, condensate from evaporation of the initial solution or a solution of purified fluorotitanic acid with a ratio of organic and aqueous phases of 20-10: 1 with the direction of the washed extract for reextraction, and the washing solution for operation concentration.

The use of an initial solution with a fluorotitanic acid content of 50-300 kg / m ³ for TiO ₂ is determined by the composition of the initial titanium raw material, the processing of which can provide solutions of fluorotitanic acid for their further pyrolysis in order to obtain titanium dioxide. Such titanium raw materials include, in particular, rutile, ilmenite, titanomagnetite, perovskite, loparite, sphene concentrates, as well as products of the processing of titanium raw materials in the form of cakes and slags. The same considerations determine the composition of impurity elements and their total content up to 50 kg / m ³ in terms of oxides.

Concentration of the initial solution to a fluorotitanic acid content of not more than 800 kg / m ³ in TiO ₂ eliminates, on the one hand, the decomposition of fluorotitanoic acid with an irreversible change in its chemical structure, and, on the other hand, provides the maximum difference in acid concentrations in the concentrated solution and in raffinate and, as a result, leads to an increase in the degree of extraction of fluorotitanic acid. The lower concentration limit of the initial solution is not lower than 500 kg / m ³ due to the peculiarities of the isotherm of extraction of fluorotitanic acid with aliphatic alcohols having a concave shape.

The cooling of the concentrated solution to a temperature of 15-30 ° C is due to the fact that when the temperature of the solution is less than 15 ° C, the viscosity of the organic and aqueous phases increases, which complicates the separation of the emulsion during extraction. Temperature above 30 ° C is undesirable due to loss of extractant due to evaporation.

The use of aliphatic alcohols with the number of carbon atoms C ₇ -C ₁₂ as an extractant, mainly 2-ethylhexanol, octanol-1, octanol-2 or a mixture thereof, is due to the high selectivity of alcohols with respect to fluorotitanic acid, and also more favorable compared to organophosphorus extractant physico-chemical properties: low density, high chemical resistance, less solubility and toxicity.

The implementation of the extraction at 3-6 stages is due to the fact that when the number of steps is less than 3, there will be an under-extraction of acid into the extract, and an increase in the number of steps above 6 is impractical, because this only leads to a slight increase in the degree of acid extraction.

The choice of the ratio of organic and aqueous phases 2-5: 1 in the extraction operation is due to the fact that when the ratio increases above 5: 1, the concentration of fluorotitanic acid in the organic phase and, accordingly, in the reextract will decrease, which is undesirable. When the phase ratio is less than 2: 1, an undesirable increase in the number of steps will take place to achieve a given degree of acid extraction into the extract.

The extraction to a content of fluorotitanic acid in the raffinate of 200-300 kg / m ³ for TiO ₂ is due to the fact that at a value below 200 kg / m ^{3 the} extraction practically stops, and at a value above 300 kg / m ^{3 there} will be an under-extraction of acid into the extract .

The implementation of re-extraction at 3-5 steps is due to the fact that when the number of steps is less than 3, incomplete extraction of acid into the re-extract will occur, and the number of steps above 5 will not lead to a significant increase in acid recovery and is excessive from the point of view of regeneration of the extractant.

The choice of 1-5: 1 ratio of organic and aqueous phases for reextraction is due to the need to obtain concentrated reextracts and to ensure a minimum content of fluorotitanic acid in the extractant, which eliminates the need for additional operations for regeneration of the extractant.

Using purified water, condensate from evaporation of the initial solution or a solution of purified fluorotitanic acid as an aqueous stripping agent, allows the extraction of fluorotitanic acid from the extract without introducing additional impurities into the reextract. As purified water, demineralized water, condensate of the secondary vapor formed during the evaporation of the solution, etc. can serve. As part of the solution of purified fluorotitanic acid, a part of the reextract diluted to a concentration of fluorotitanic acid sufficient to regenerate the extractant can be used.

Reextraction to a content of fluorotitanic acid in a reextract of not more than 500 kg / m ³ according to TiO ₂ is dictated by the need to obtain concentrated solutions of fluorotitanoic acid to expand their scope, ease of storage and transportation. The possibility of obtaining such reextracts is based on the use of concentrated solutions in the extraction process with a fluorotitanic acid content of 800 kg / m ³ or less in TiO ₂ and is due to the peculiarities of the form of the isotherm of fluorotitanic acid extraction with aliphatic alcohols with the number of carbon atoms C ₇ -C ₁₂ .

The return to the operation of concentration up to 80 vol.% Raffinate inclusively leads to an increase in the weight flow of acid during its concentration and extraction, which helps to increase the degree of extraction of fluorotitanic acid. If the above value is exceeded, an undesirable increase in the concentration of impurity elements in the extraction operation will be observed, which will lead to their coextraction with acid and deterioration in the quality of the back-extract.

The washing of the extract with purified water, condensate from evaporation of the initial solution or with a solution of purified fluorotitanic acid is due to the need for maximum removal of impurity elements for the subsequent preparation of a conditioned solution of purified fluorotitanic acid. As purified water, as in the case of reextraction, demineralized water or a condensate of secondary vapor formed during evaporation of the solution can serve, and part of the reextract can be used as a solution of purified fluorotitanic acid.

The choice of the ratio of organic and aqueous phases O: B = 20-10: 1 when washing the extract is due to the fact that this ratio provides a reduction to 95-99% of the concentration of impurity elements.

For a clearer understanding of the invention and an additional assessment of its features, the following are embodiments of a method for processing a solution containing fluorotitanic acid and impurity elements, which are illustrated in the following drawings.

Figure 1 shows a schematic flow chart of the processing of a fluorine-titanium solution without washing the extract;

 figure 2 shows the isotherm for the extraction of fluorotitanic acid with aliphatic alcohols from a concentrated fluorotitanic solution;

figure 3 shows a schematic flow chart of the processing of a fluorine-titanium solution with washing the extract.

The essence of the proposed method, the processing of a solution containing fluorotitanic acid and impurity elements, is as follows.

As a result of mixing the initial processed production solution 1 (see Fig. 1) with a portion of raffinate 2, an initial fluorotitanium solution 3 is formed containing 50 kg / m ³ of TiO ₂ or more fluorotitanic acid, as well as impurity elements with a total content of their oxides of up to 50 kg / m ³ . The combined solution 3 is directed to concentration 4, which is carried out by evaporation of the solution until the content of fluorotitanic acid in it is not more than 800 kg / m ³ according to TiO ₂ , which excludes the decomposition of fluorotitanoic acid. Condensate 5 formed during evaporation is used as stripping agent 6, and excess condensate 7 is sent for further disposal.

One stripped off solution 8 after cooling to a temperature of 15-30 ° С, filtration and separation of the precipitate (not shown) goes to extraction 9, where in countercurrent mode it interacts with extractant 10 - aliphatic alcohol in the form of 2-ethylhexanol, octanol-2, octanol- 1 or mixtures thereof. Based on the equilibrium extraction isotherm (see figure 2), it can be seen that when the concentration of fluorotitanic acid in the aqueous phase is less than 300 kg / m ³ by TiO _{2, the} extraction of acid into the organic phase is negligible. Noticeable extraction of the acid begins with its concentration in the solution of about 380 kg / m ³ according to TiO ₂ .

The extraction is carried out in conventional mixing-settling extractors with 3-6 stages, in which the main part of fluorotitanic acid is extracted into the organic phase. The acid-poor aqueous phase - raffinate 11 contains almost all impurity elements and up to 300 kg / m ³ of TiO _{2 of} fluorotitanic acid, and the organic phase - extract 12 mainly contains purified fluorotitanic acid. The extract 12 then goes to re-extraction 13, where condensate 6 from evaporation of the initial solution 3 is used as the re-extractant. If necessary, the re-extraction can be carried out with demineralized water or a diluted solution of purified fluorotitanic acid (not shown in Fig. 1).

Reextraction is also carried out in countercurrent mode in a mixer-settler type extractor with a number of stages of 3-5, where fluorotitanic acid passes from extract 12 to the aqueous phase. When this extract 12 loses most of the acid and in the form of a regenerated organic phase 10 is sent again to the extraction 9. The resulting reextract 14 contains purified fluorotitanic acid with almost complete absence of impurities and is the target product. Part of raffinate 2 in an amount of up to 80% is returned to the concentration operation 4, and the remaining part of raffinate 15 is removed from the circuit and sent for recycling.

Depending on the requirements for purified fluorotitanic acid and the composition of impurity elements in the initial solution, a variant of the method according to the invention is possible, including washing the extract. In this case (see FIG. 3), after extraction 9, the organic phase 12 enters the washing operation 16, which is carried out by condensate 17 from evaporation of the initial solution 3 in countercurrent mode in an extractor of the mixer-settler type with the number of stages 2-5. For washing, you can use demineralized water or a solution of purified fluorotitanic acid (not shown in figure 3). The washing solution 18, containing a part of fluorotitanic acid and impurity elements, is sent to the concentration operation, combining it with the processed production solution 1. The washed extract 19 is fed to re-extraction 13. The process is then carried out similarly to that described above.

The essence and advantages of the present invention can be explained in more detail by the following examples of specific performance of the method.

Example 1

Mix 50 m ^{3 of the} initial fluorotitanium solution obtained by hydrofluoride opening of titanium raw materials containing 50 kg / m ^{3 of} fluorotitanoic acid and impurity elements: Na, K, Ca, Sr, Si, Mn, Mg, V, Zn, Fe in an amount of 48 , 5 kg / m ³ in terms of the amount of oxides, with 3.414 m ^{3 of} raffinate (80% of the total raffinate) containing 200 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 6.9 kg / m ³ in terms of the amount of oxides . The resulting fluorotitanium solution is directed to the evaporation operation. After cooling to a temperature of 17 ° C, filtering and separating the precipitate, a concentrated solution in an amount of 6.071 m ³ containing 500 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 5.0 kg / m ³ in terms of the amount of oxides (0.304 wt.% ), goes to extraction, where in countercurrent mode it interacts with 29.972 m ^{3 of the} regenerated organic phase in the form of octanol-1 (O: B = 4.9) with a residual fluorotitanic acid content of 10 kg / m ³ . The extraction is carried out in conventional mixing-settling extractors with 4 steps, in which the main part of the fluorotitanic acid is extracted into the organic phase. The acid-poor aqueous phase (raffinate) in an amount of 4.267 m ³ contains impurity elements in an amount of 6.9 kg / m ³ , calculated on the sum of the oxides and 200 kg / m ^{3 of} fluorotitanic acid. The organic phase (extract) in an amount of 31.025 m ³ contains fluorotitanic acid with a concentration of 80 kg / m ³ . The extract is then transferred to stripping, where condensate from evaporation of the initial solution is used as stripping agent.

Reextraction is also carried out in countercurrent mode in a mixer-settler type extractor with a number of stages of 3 (O: B = 3.4), where fluorotitanic acid passes from the extract to the aqueous phase. In this case, the extract loses most of the acid and in the form of regenerated octanol-1 with a residual content of fluorotitanic acid of 10 kg / m ^{3 is} redirected to the extraction. The obtained re-extract, which is the target product, in an amount of 10.911 m ³ contains 200 kg / m ^{3 of} purified fluorotitanic acid and impurity elements in an amount of 0.05 kg / m ³ in terms of the amount of oxides (0.004 wt.%). The residual portion of the raffinate in an amount of 0.853 m ³ (1.76% of the volume of the initial solution) with a fluorotitanic acid content of 200 kg / m ^{3 is} removed from the circuit and sent for disposal. The degree of extraction of fluorotitanic acid in re-extract is 92.7% at a concentration of fluorotitanic acid of 200 kg / m ³ .

Example 2

Mix 18 m ^{3 of the} initial fluorotitanium solution obtained by hydrofluoride opening of titanium raw materials containing 120 kg / m ^{3 of} fluorotitanic acid and impurity elements: Na, Ca, Zr, Cr, Al, Mn, Fe in an amount of 23.2 kg / m ³ in terms of the amount of oxides, from 1.412 m ^{3 of} raffinate (60% of the total volume of raffinate) containing 220 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 7.45 kg / m ³ in terms of the amount of oxides. The resulting fluorotitanium solution is directed to the evaporation operation. After cooling to a temperature of 20 ° C, filtration and separation of the precipitate, a concentrated solution in an amount of 4.003 m ³ containing 600 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 4.5 kg / m ³ in terms of the amount of oxides (0.26 wt. %), is supplied to extraction, where it interacts in countercurrent mode with 19.928 m ^{3 of the} regenerated organic phase in the form of octanol-2 (O: B = 5.0) with a residual fluorotitanic acid content of 10 kg / m ³ . The extraction is carried out in conventional mixing-settling extractors with 5 steps, in which the bulk of fluorotitanic acid is extracted into the organic phase. The acid-poor aqueous phase (raffinate) in an amount of 2.353 m ³ contains impurity elements in an amount of 7.45 kg / m ³ in terms of the amount of oxides and 220 kg / m ^{3 of} fluorotitanic acid, and the organic phase (extract) in an amount of 20.838 m ³ - fluorotitanic acid with a concentration of 100 kg / m ³ . The extract then goes to reextraction, where purified water is used as a reextractor.

Reextraction is also carried out in countercurrent mode in a mixer-settler type extractor with a number of steps of 3 (O: B = 3.5), where fluorotitanic acid passes from the extract to the aqueous phase. In this case, the extract loses most of the acid and in the form of regenerated octanol-2 with a residual content of fluorotitanic acid of 10 kg / m ^{3 is} redirected to the extraction. The obtained re-extract, which is the target product, in an amount of 7.538 m ³ contains 250 kg / m ^{3 of} purified fluorotitanic acid and impurity elements in an amount of 0.06 kg / m ³ in terms of the amount of oxides (0.0045 wt.%). The residual portion of the raffinate in the amount of 0.941 m ³ (5.23% of the volume of the initial solution) with the content of fluorotitanic acid 220 kg / m ^{3 is} removed from the scheme and sent for disposal. The degree of extraction of fluorotitanic acid in re-extract is 90.1% at a concentration of fluorotitanic acid of 250 kg / m ³ .

Example 3

Mix 30 m ^{3 of the} initial fluorotitanium solution obtained by hydrofluoride opening of titanium raw materials containing 200 kg / m ^{3 of} fluorotitanic acid and impurity elements: Na, K, Mo, Al, Cr, Mn, Fe in the amount of 10.3 kg / m in in terms of the amount of oxides, from 1,226 m of raffinate (35% of the total volume of the raffinate) containing 280 kg / m ^{3 of} fluorotitanic acid and impurity elements in terms of the amount of oxides of 7.6 kg / m ³ . The resulting fluorotitanium solution is directed to the evaporation operation. After cooling to a temperature of 18 ° C, filtering and separating the precipitate, a concentrated solution in an amount of 8.336 m ³ containing 750 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 3.4 kg / m ³ in terms of the amount of oxides (0.178 wt.% ), goes to extraction, where in countercurrent mode it interacts with 22.324 m ^{3 of the} regenerated organic phase in the form of a mixture of alcohols of the C ₇ -C ₉ fraction (O: B = 2.7) with a residual fluorotitanic acid content of 10 kg / m ³ . The extraction is carried out in conventional mixing-settling extractors with 3 stages, in which the bulk of fluorotitanic acid is extracted into the organic phase. The acid-poor aqueous phase (raffinate) in an amount of 3.502 m ³ contains impurity elements in an amount of 7.6 kg / m, calculated on the sum of oxides and 280 kg / m of fluorotitanic acid, and the organic phase (extract) in an amount of 25.629 m ³ contains fluorotitanic acid with a concentration of 214 kg / m ³ . The extract is then transferred to a reextraction, where a diluted reextract is used as a stripping agent.

Reextraction is also carried out in countercurrent mode in a mixer-settler-type extractor with a number of stages of 4 (O: B = 1.5), where fluorotitanic acid passes from the extract to the aqueous phase. In this case, the extract loses most of the acid and, in the form of a regenerated mixture of alcohols of the C ₇ -C ₉ fraction with a residual fluorotitanic acid content of 10 kg / m ^{3, is} redirected to the extraction. The obtained re-extract, which is the target product, in an amount of 15,801 m ³ contains 400 kg / m ^{3 of} purified fluorotitanic acid and impurity elements in an amount of 0.12 kg / m ³ in terms of the amount of oxides (0,0009 wt.%). The remainder of the raffinate in an amount of 2.276 m ³ with a content of fortitanic acid of 280 kg / m ³ (7.58% of the volume of the initial solution) is removed from the scheme and sent for disposal. The degree of extraction of fluorotitanic acid in re-extract is 88.9% at a concentration of fluorotitanic acid 400 kg / m ³ .

The implementation of the method of processing fluorotitanium solution with washing the extract.

Example 4

Mix 16 m ^{3 of the} initial fluorotitanium solution obtained by hydrofluoride opening of titanium raw materials containing 170 kg / m ^{3 of} fluorotitanoic acid and impurity elements: Na, K, Ca, Cr, Sr, Si, Zn, Mg, Fe in an amount of 11, 5 kg / m ³ in terms of the amount of oxides, with 2.173 m ^{3 of} raffinate (50% of the total raffinate) containing 240 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 6.9 kg / m ³ in terms of the amount of oxides and 4.994 m ³ of wash solution containing 430 kg / m ³ fluorotitanic acid and trace elements in an amount of 0.14 kg / m ³ based on ummah oxide (0.21 wt.%). The resulting fluorotitanium solution is directed to the evaporation operation. After cooling to a temperature of 25 ° C, filtering and separating the precipitate, a concentrated solution in an amount of 8.128 m ³ containing 650 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 3.8 kg / m ³ in terms of the amount of oxides is fed to the extraction, where in countercurrent mode it interacts with 32.988 m ^{3 of the} regenerated organic phase in the form of 2-ethylhexanol (O: B = 4.1) containing 20 kg / m ^{3 of} residual fluorotitanic acid. The extraction is carried out in conventional mixing-settling extractors with 5 steps, in which the bulk of fluorotitanic acid is extracted into the organic phase. The acid-poor aqueous phase (raffinate) in an amount of 4.346 m ³ contains impurity elements in an amount of 6.9 kg / m ³ in terms of the sum of oxides and 240 kg / m ^{3 of} fluorotitanic acid, and the organic phase (extract) in an amount of 35 m ³ - fluorotitanic acid with a concentration of 140 kg / m ³ . The extract then goes to the washing, for which 3.299 m ^{3 of} condensate is used from evaporation of the initial solution. The washing is carried out in countercurrent mode in an extractor of the mixer-settler type with the number of stages 2 (O: B = 10.6). The saturated wash solution is combined, as mentioned above, with the processed production solution - fluorotitanic acid and sent to the concentration stage. The washed extract is fed to stripping, where condensate from evaporation of the initial solution in the amount of 5.302 m ^{3 is} used as stripping agent.

Reextraction is carried out in countercurrent mode in a mixer-settler type extractor with a number of stages of 3 (O: B = 5), where fluorotitanic acid passes from the washed extract to the aqueous phase. In this case, the extract loses most of the acid and, in the form of regenerated 2-ethylhexanol with a residual fluorotitanic acid content of 20 kg / m ^{3, is} redirected to the extraction. The obtained stripping, which is the target product, in an amount of 6.976 m ³ contains 300 kg / m ^{3 of} purified fluorotitanic acid and impurity elements in an amount of 0.03 kg / m ³ in terms of the amount of oxides (0.002 wt.%). The residual portion of the raffinate in the amount of 2.173 m ³ (13.5% of the volume of the initial solution) with a fluorotitanic acid content of 240 kg / m ^{3 is} removed from the circuit and sent for disposal. The degree of extraction of fluorotitanoic acid in re-extract, which is the target product, is 80.0% at a concentration of fluorotitanoic acid 300 kg / m ³ .

Example 5

Mix 12 m ^{3 of the} initial fluorotitanium solution obtained by hydrofluoride opening of titanium raw materials containing 300 kg / m ^{3 of} fluorotitanoic acid and impurity elements: Na, K, Ca, Sr, Nb, Si, Ta, Mn, Fe in the amount of 15 kg / m ³ in terms of the amount of oxides, from 0.205 m ^{3 of} raffinate (10.0% of the total volume of raffinate) containing 300 kg / m of fluorotitanic acid and impurity elements in an amount of 7.9 kg / m in terms of the amount of oxides and 1,686 m ³ a washing solution containing 560 kg / m ^{3 of} fluorotitanic acid impurity elements in an amount of 0.75 kg / m ³ in terms of amounts in oxides. The resulting fluorotitanium solution is directed to the evaporation operation. After cooling to a temperature of 30 ° C, filtering and separating the precipitate, a concentrated solution in an amount of 5.701 m ³ containing 800 kg / m ^{3 of} fluorotitanic acid and impurity elements in an amount of 3.1 kg / m ³ in terms of the amount of oxides (0.16 wt. .%) goes to extraction, where in countercurrent mode it interacts with 17.638 m ^{3 of the} regenerated organic phase in the form of a mixture of alcohols of fraction C ₁₀ -C ₁₂ (O: B = 3.1) containing 20 kg / m ^{3 of} residual fluorotitanic acid . The extraction is carried out in conventional mixing-settling extractors with 6 stages, in which the main part of the fluorotitanic acid is extracted into the organic phase. The acid-poor aqueous phase (raffinate) in an amount of 2.047 m ³ contains impurity elements in an amount of 7.9 kg / m ³ in terms of the sum of oxides and 300 kg / m ^{3 of} fluorotitanic acid, and the organic phase (extract) in an amount of 19.543 m ³ - fluorotitanic acid with a concentration of 220 kg / m ³ . The extract then goes to the washing, for which 0.977 m ^{3 of} condensate is used from evaporation of the initial solution. Washing is carried out in countercurrent mode in an extractor of the mixer-settler type with a number of steps of 3 (O: B = 20). The saturated wash solution is combined, as mentioned above, with the processed production solution - fluorotitanic acid and sent to the concentration stage. The washed extract is supplied for stripping, where condensate from evaporation of the initial solution in the amount of 3.523 m ^{3 is} used as stripping agent.

Reextraction is carried out in countercurrent mode in a mixer-settler type extractor with a number of steps of 5 (O: B = 3.5), where fluorotitanic acid passes from the washed extract to the aqueous phase. In this case, the extract loses most of the acid and in the form of a regenerated mixture of alcohols of the C ₁₀ -C ₁₂ fraction with a residual fluorotitanic acid content of 20 kg / m ^{3 is} redirected to the extraction. The obtained re-extract, which is the target product, in an amount of 6.006 m ³ contains 500 kg / m ^{3 of} purified fluorotitanic acid and impurity elements in an amount of 0.04 kg / m ³ in terms of the amount of oxides (0.0024 wt.%). The residual portion of the raffinate in the amount of 1,842 m ³ (15.4% of the volume of the initial solution) with a fluorotitanic acid content of 300 kg / m ^{3 is} removed from the circuit and sent for disposal. The degree of extraction of fluorotitanic acid in the re-extract, which is the target product, is 84.4% at a concentration of fluorotitanic acid of 500 kg / m ³ .

From the above Examples, it is seen that the proposed method for processing a solution containing fluorotitanic acid and impurity elements allows, with a high degree of fluorotitanic acid extraction, to increase the acid concentration to 500 kg / m ³ according to TiO ₂ and to ensure a minimum content of impurity elements in it regardless of their composition. This allows you to process purified fluorotitanic acid by pyrolysis to obtain titanium dioxide, including high purity, for various purposes. The method allows to optimize the material flows of the organic and aqueous phases by adjusting the amount of raffinate returned to the concentration operation and the amount of waste solution. When implementing the method, standard equipment is used.

Claims (9)

1. A method of processing a solution containing fluorotitanic acid and impurity elements, including concentrating the initial solution, mixing the concentrated solution with an organic solvent in the form of a neutral oxygen-containing extractant, extraction of fluorotitanic acid with the main part of the acid into the organic phase, and the main part of the impurity into the aqueous phase elements, separation of the organic and aqueous phases with the formation of an extract of fluorotitanic acid and raffinate, the return of a portion of the raffinate to the concentrate operation extraction, acid reextraction with an aqueous stripping agent to obtain a reextract in the form of a solution of purified fluorotitanic acid and returning the regenerated organic phase to extraction, characterized in that the initial solution is concentrated until the content of fluorotitanic acid in it is not more than 800 kg / m ³ according to TiO ₂ , as of a neutral oxygen-containing extractant, aliphatic alcohols are used, extraction is carried out in 3-6 steps until the fluorotitanic acid content in the raffinate is 200-300 kg / m ³ according to TiO ₂ , and re-extraction is carried out for 3-5 steps with a ratio of organic and aqueous phases of 1-5: 1. 2. The method according to claim 1, characterized in that the use of an initial solution containing 50-300 kg / m ^{3 of} fluorotitanic acid in terms of TiO ₂ , and as impurity elements at least one of the elements: Al, Ca, Cl, Cr, Fe, Mg, Mn, Na, Nb, Si, Ta, Ti, V, Zn, Zr with a total oxide content of impurity elements up to 50 kg / m ³ . 3. The method according to claim 1 or 2, characterized in that the concentration of the initial solution is carried out by evaporation to the content of fluorotitanic acid 500-800 kg / m ³ in TiO ₂ , after which the solution is cooled to a temperature of 15-30 ° C. 4. The method according to any one of claims 1 to 3, characterized in that as aliphatic alcohols use alcohols with the number of carbon atoms C ₇ -C ₁₂ , mainly 2-ethylhexanol, octanol-1, octanol-2, or mixtures thereof. 5. The method according to any one of claims 1 to 4, characterized in that the extraction is carried out at a ratio of organic and aqueous phases of 2-5: 1. 6. The method according to any one of claims 1 to 5, characterized in that purified water, condensate from evaporation of the initial solution or a solution of purified fluorotitanic acid are used as an aqueous stripping agent. 7. The method according to any one of claims 1 to 6, characterized in that the stripping is carried out to the content of fluorotitanic acid in the stripping no more than 500 kg / m ³ according to TiO ₂ . 8. The method according to claim 1, characterized in that up to 80 vol.% Raffinate is returned to the concentration operation. 9. The method according to any one of claims 1 to 8, characterized in that after the extraction, the extract is washed with purified water, condensate from evaporation of the initial solution or a solution of purified fluorotitanic acid with a ratio of organic and aqueous phases of 20-10: 1 with the direction of the washed extract to re-extraction, and the washing solution for the concentration operation.

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