Method for removing impurities from high-purity metatitanic acid

Abstract

The application discloses a method for removing impurities from high-purity metatitanic acid, and relates to the field of material chemical preparation. The method comprises the following steps: firstly, adjusting the pH of metatitanic acid raw material liquid by using an acid washing solution, and then performing acid washing, wherein the acid washing solution is acetic acid solution, and the acid washing temperature is 50-60 DEG C; secondly, mixing the metatitanic acid after acid washing with an alkali washing solution to perform alkali washing, wherein the alkali washing solution is ammonia water solution, and the pH of the system is adjusted to 8-10; finally, washing the metatitanic acid after alkali washing with water. The application constructs a three-step mild purification process system of "acetic acid acid washing-ammonia water alkali washing-hot water washing", and realizes step-by-step efficient removal of iron ions and sulfate ions in the metatitanic acid through the synergistic cooperation of acid washing, alkali washing and hot water washing. The iron content can be reduced to below 10 ppm, and the sulfur content can be reduced to below 0.1%, so that the strict requirements of high-purity metatitanic acid on high-purity titanium dioxide, high-end electronic ceramics and new energy battery materials and the like can be met.

Description

Technical Field

[0001] This invention relates to the field of materials chemical preparation, specifically to a method for removing impurities from high-purity metatitanic acid. Background Technology

[0002] Metatitanic acid is a key intermediate product in the sulfuric acid process for producing titanium dioxide, and also an important precursor for preparing high-value-added titanium-based materials such as nano-sized titanium dioxide and barium titanate. Due to its mature technology, readily available raw materials, and low production cost, the sulfuric acid process is currently the main industrial method for producing metatitanic acid. However, metatitanic acid obtained by the sulfuric acid process inevitably contains a large number of impurity ions, especially sulfate ions (SO42-). 2- ) and iron ions (Fe 3+ Fe 2+ This severely restricts its application in fields such as high-purity titanium dioxide, high-end electronic ceramics, and new energy battery materials.

[0003] To reduce the impurity content in metatitanic acid, the current industrial practice mainly uses metatitanic acid after secondary washing to prepare high-purity metatitanic acid. Water washing is primarily used to remove soluble impurities such as iron, sulfur, and heavy metals from the primary metatitanic acid, with some processes supplemented by reduction bleaching to enhance purification. However, relying solely on physical washing has limited effectiveness in removing impurities strongly adsorbed on the crystal lattice and particle surface, easily resulting in residual impurities such as iron and sulfur, making it difficult to consistently meet the requirements for high-purity products. Furthermore, washing consumes a large amount of water, generates significant amounts of acidic wastewater, and incurs high environmental treatment costs. The production process is easily affected by operating and equipment conditions, resulting in poor product purity and batch stability, and particle agglomeration, affecting the performance of subsequent products. Moreover, traditional processes only focus on impurity removal, lacking simultaneous control over particle structure, resulting in long overall processes, high energy consumption, and large reagent consumption, making it difficult to meet the demands of high-end fields for stable, efficient, and environmentally friendly preparation of high-purity metatitanic acid.

[0004] Chinese patent CN114671460A discloses a method for removing impurities from industrial metatitanic acid in a short-process sulfuric acid method for titanium dioxide production. The method involves a process of pulping and dispersing, adding a complexing agent (sulfosalicylic acid, citric acid), adding a dispersant (sodium dodecyl sulfonate), hydrothermal crystallization (110–180℃, 4–48 h), and purification and washing to remove impurity ions. However, while the hydrothermal treatment used in this patent can improve the impurity removal effect, it is energy-intensive and has a long processing cycle. Furthermore, this patent requires the addition of complexing and dispersing agents for impurity removal, which, while improving efficiency, increases reagent consumption and process complexity, and may also introduce other impurities.

[0005] Chinese patent CN118479532A proposes a method for removing impurities from metatitanic acid without hydrothermal treatment or additional additives. This method involves slurrying and dispersing the metatitanic acid filter cake from the sulfuric acid process in an aqueous sodium carbonate solution, stirring thoroughly at room temperature, filtering, and washing with sodium carbonate solution until no SO4 is present.2- The ions are present; the resulting filter cake is then slurried and dispersed in a dilute hydrochloric acid aqueous solution, stirred evenly at room temperature, filtered, and washed with dilute hydrochloric acid solution until no CO3 is present. 2- The solution contains iron ions; finally, it is washed with water until the filtrate is neutral to obtain purified metatitanic acid filter cake. This method is carried out entirely at room temperature, and the purified metatitanic acid contains ≤5 ppm iron and ≤10 ppm sulfur. However, the alkaline and acid washing methods used in this patent have several drawbacks. First, there is a risk of residual sodium and chloride ions. Second, the method uses large quantities of acid and alkali solutions, resulting in significant wastewater generation and high environmental and treatment costs.

[0006] In summary, existing metatitanic acid purification technologies generally suffer from problems such as incomplete impurity removal, easy introduction of new impurities, and large wastewater generation, making it difficult to meet the increasingly stringent quality requirements for high-purity metatitanic acid in high-end applications. Therefore, there is an urgent need to develop a novel metatitanic acid purification method that can efficiently remove key impurities such as iron and sulfur without introducing new impurities, while also being simple in process, environmentally friendly, and easy to scale up for production. Summary of the Invention

[0007] Therefore, the present invention provides a method for removing impurities from high-purity metatitanic acid to solve the problems in the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: According to the present invention, a method for removing impurities from high-purity metatitanic acid includes the following steps: Step 1, pickling step After adjusting the pH of the metatitanic acid raw material solution with pickling solution, pickling is performed. The pickling solution is an acetic acid solution, and the pickling temperature is 50-60℃. Step 2, Alkali Washing Step The acid-washed metatitanic acid is mixed with an alkaline washing solution, which is an ammonia solution, and the pH of the system is adjusted to 8-10. Step 3, water washing step The metatitanic acid, after being washed with alkali, was then pulped and washed with water.

[0009] Furthermore, in step one, the metatitanic acid raw material solution is prepared by adding metatitanic acid raw material to water and dispersing it, with the pH of the slurry system between 2.20 and 2.50.

[0010] This invention uses acetic acid as a pickling agent, leveraging its weak acidity and complexing properties to dissolve and remove iron-based impurities adsorbed on the surface and within the pores of metatitanic acid particles. As an organic acid, acetic acid does not contain difficult-to-remove inorganic anions such as chloride ions and nitrate ions, thus avoiding the introduction of new ionic impurities during purification. Furthermore, acetic acid is mild and will not corrode the metatitanic acid matrix or cause particle gelation at 50–60°C, effectively removing impurities while maintaining the stability of the material's structure and morphology.

[0011] This invention uses ammonia as an alkaline washing agent. The weak alkalinity of ammonia neutralizes residual acetic acid and acidic sites, and through neutralization and displacement reactions, converts residual sulfate ions into a elutable form. Ammonia decomposes upon heating into NH3 and H2O, without introducing metallic cation impurities such as sodium and potassium, thus avoiding the risk of residual metal ions that may arise from sodium carbonate alkaline washing in existing technologies. Furthermore, the ammonia alkaline washing conditions are mild and will not damage the metatitanic acid particle structure or cause particle agglomeration.

[0012] Furthermore, the pH of the metatitanic acid feed solution was adjusted to 2.10-2.20 using pickling solution.

[0013] Furthermore, in step two, the alkaline washing temperature is 50–60°C.

[0014] Furthermore, the method also includes a filtration step after the acid washing step, the alkali washing step, and the water washing step, namely, filtration after acid washing, filtration after alkali washing, and filtration after water washing.

[0015] Furthermore, in the filtration step, a filter aid is added to the metatitanic acid slurry.

[0016] Furthermore, the filter aid is nonionic polyacrylamide.

[0017] Furthermore, the amount of nonionic polyacrylamide added is 0.05% to 0.2% of the mass of metatitanic acid. As an example, it is preferred that the amount of nonionic polyacrylamide added is 0.1% of the mass of metatitanic acid.

[0018] This invention adds nonionic polyacrylamide as a filter aid after each of the acid washing, alkali washing, and water washing stages to assist filtration. This significantly improves the filtration performance of the metatitanic acid slurry, increases dewatering efficiency, reduces the moisture content of the filter cake, and reduces material loss during the filtration process, thereby increasing product yield. Nonionic polyacrylamide does not carry an ionic charge and will not electrostatically adsorb ions in the slurry or introduce new impurities, thus ensuring product purity while enhancing filtration.

[0019] Furthermore, in the water washing step, in step three, the water washing temperature is 50-60℃, and the number of water washing cycles is three.

[0020] This invention uses a temperature of 50-60℃ for washing, which significantly improves the diffusion rate and mass transfer efficiency of ions compared to room temperature operation, making the removal of impurities more thorough and complete. At the same time, the temperature is mild and moderate, avoiding the problems of high energy consumption, long cycle and demanding equipment requirements caused by high-temperature hydrothermal treatment, thus achieving a balance between efficient impurity removal and energy saving.

[0021] Furthermore, in the water washing step, specifically in step three, the washing endpoint is defined as the pH of the filtrate after washing being neutral. This invention uses the neutral pH of the filtrate after washing as the criterion for determining the washing endpoint, ensuring a clear and controllable endpoint, which is beneficial for guaranteeing the stability and consistency of purity across different batches of products.

[0022] The purified metatitanic acid of this invention contains ≤10ppm iron and ≤0.1% sulfur. Other impurity ions are all ≤1ppm.

[0023] The metatitanic acid raw material used in this invention is metatitanic acid produced by the sulfuric acid process. Preferably, it is a metatitanic acid filter cake produced by the two-wash sulfuric acid process.

[0024] The present invention relates to the application of purified metatitanic acid in the preparation of battery-grade barium titanate, electronic-grade barium titanate, titanium-based oxide functional ceramics, battery separator modifiers, or electrode interface buffer layer materials.

[0025] The present invention has the following advantages: This invention constructs a three-step mild purification process system of "acetic acid washing—ammonia alkaline washing—hot water washing." Through the synergistic effect of acid washing, alkaline washing, and hot water washing, stepwise and efficient removal of iron ions and sulfate ions from metatitanic acid is achieved. The iron content can be reduced to below 10 ppm and the sulfur content to below 0.1%, which can meet the stringent requirements for high-purity metatitanic acid in fields such as high-purity titanium dioxide, high-end electronic ceramics, and new energy battery materials.

[0026] The entire purification process of this invention is carried out under mild conditions, without the need for high-temperature hydrothermal or high-pressure reactions or the addition of complex additives such as complexing agents and dispersants. The process is simple, easy to operate, the reagents are inexpensive and readily available, energy consumption is low, and wastewater generation is small. It has good environmental and economic benefits and is easy to realize large-scale industrial production. Attached Figure Description

[0027] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0028] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0029] Figure 1 The images shown are comparative images of the appearance of different products after calcination provided in Experimental Example 6 of the present invention, where A is Example 1 and B is Comparative Example 8. Detailed Implementation

[0030] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products; different manufacturers and models of raw materials do not affect the implementation of the technical solution or the achievement of the technical effect of this invention.

[0032] Example 1 This embodiment provides a method for removing impurities from high-purity metatitanic acid, including the following steps: Step 1, Acid Washing: Weigh 100g of sulfuric acid. Prepared The second-washed metatitanic acid filter cake (raw material iron content 29.6 ppm, sulfur content 1.38%) was mixed with 10 times its weight of deionized water (water temperature 50℃) and stirred for 1 hour to obtain a homogeneous slurry. At this point, the pH of the slurry system was 2.30. The pH of the slurry was adjusted to 2.10 with acetic acid solution, and stirring was continued for 1 hour. Then, 0.1% of the metatitanic acid mass of nonionic polyacrylamide (filter aid concentration of 2.5% aqueous solution) was added, stirred evenly, and filtered while hot to obtain the acid-washed metatitanic acid filter cake.

[0033] Step 2, alkaline washing: Add the acid-washed metatitanic acid filter cake to 10 times its weight of deionized water (water temperature 50℃) and stir to disperse. Adjust the pH of the system to 8.10 with ammonia solution. Continue stirring for 1 hour, then add 0.1% nonionic polyacrylamide by weight of metatitanic acid. Stir evenly and filter to obtain alkaline-washed metatitanic acid filter cake.

[0034] Step 3, water washing: Add the alkaline-washed metatitanic acid filter cake to 10 times its mass of deionized water (water temperature 50℃) and stir to disperse. After stirring for 0.5 hours, add 0.1% (by mass of metatitanic acid) of nonionic polyacrylamide, stir evenly and filter. Repeat the above water washing operation three times until the pH of the filtrate is neutral to obtain purified metatitanic acid filter cake.

[0035] The purified metatitanic acid obtained in this example contained 7.3 ppm of iron and 0.08% of sulfur. The purified metatitanic acid obtained in this example contained ≤1 ppm of other impurity ions such as calcium, magnesium, aluminum, silicon, chromium, manganese, and nickel. The TiO2 content after calcination was 99.26%.

[0036] Example 2 The difference between this embodiment and Embodiment 1 is that: in the acid washing step, the pH of the slurry is adjusted to 2.20 using acetic acid solution; in the alkaline washing step, the pH of the system is adjusted to 8.30 using ammonia solution; and the water washing temperature is 60℃. The remaining steps and parameters are the same as in Embodiment 1.

[0037] The purified metatitanic acid obtained in this example was found to contain 6.8 ppm of iron, 0.07% of sulfur, and 99.30% TiO2 after calcination.

[0038] Example 3 The difference between this embodiment and Example 1 is that the amount of nonionic polyacrylamide added is 0.05% of the mass of metatitanic acid. The remaining steps and parameters are the same as in Example 1.

[0039] The purified metatitanic acid obtained in this example was found to contain 8.1 ppm of iron, 0.09% of sulfur, and 99.15% TiO2 after calcination.

[0040] Example 4 The difference between this embodiment and Example 1 is that the amount of nonionic polyacrylamide added is 0.2% of the mass of metatitanic acid. The remaining steps and parameters are the same as in Example 1.

[0041] The purified metatitanic acid obtained in this example was found to contain 7.0 ppm of iron, 0.08% of sulfur, and 99.20% TiO2 after calcination.

[0042] Example 5 The difference between this embodiment and Embodiment 1 is that the second batch of sulfuric acid-washed metatitanic acid filter cake is used as raw material (raw material iron content 30.2 ppm, sulfur content 1.42%). The remaining steps and parameters are the same as in Embodiment 1.

[0043] The purified metatitanic acid obtained in this example was found to contain 7.5 ppm of iron, 0.09% of sulfur, and 99.18% TiO2 after calcination.

[0044] Comparative Example 1 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, and test it directly without any washing treatment.

[0045] Tests showed that the raw material metatitanic acid contained 29.6 ppm of iron, 1.38% of sulfur, and 94.00% of TiO2 after calcination.

[0046] Comparative Example 2 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, add it to 10 times its weight of deionized water (room temperature) and slurry and disperse. After stirring for 1 hour, filter. Repeat the water washing operation three times. Do not perform acid washing or alkali washing.

[0047] The iron content in the metatitanic acid obtained in this comparative example was 25.4 ppm, the sulfur content was 1.25%, and the TiO2 content after calcination was 94.50%.

[0048] Comparative Example 3 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, and perform acetic acid washing (pH 2.10, 50℃) according to step one of Example 1. Then, perform hot water washing three times (50℃) according to step three of Example 1, without performing alkaline washing. After each washing step, add 0.1% nonionic polyacrylamide as a filter aid.

[0049] The iron content in the metatitanic acid obtained in this comparative example was 8.5 ppm, the sulfur content was 0.85%, and the TiO2 content after calcination was 98.20%.

[0050] Comparative Example 4 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, and perform alkaline washing with ammonia water (pH 8.10, 50℃) according to step two of Example 1. Then, perform hot water washing three times (50℃) according to step three of Example 1, without acid washing. After each washing step, add 0.1% nonionic polyacrylamide as a filter aid.

[0051] The iron content in the metatitanic acid obtained in this comparative example was 18.7 ppm, the sulfur content was 0.12%, and the TiO2 content after calcination was 98.50%.

[0052] Comparative Example 5 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1. First, perform alkaline washing with ammonia water (pH 8.10, 50℃) according to step two of Example 1. Then, perform acid washing with acetic acid (pH 2.10, 50℃) according to step one of Example 1. Finally, perform hot water washing three times (50℃) according to step three of Example 1. After each washing stage, add 0.1% nonionic polyacrylamide as a filter aid.

[0053] The iron content in the metatitanic acid obtained in this comparative example was 12.3 ppm, the sulfur content was 0.09%, and the TiO2 content after calcination was 98.70%.

[0054] Comparative Example 6 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, and perform acid washing (acetic acid, pH 2.10), alkali washing (ammonia, pH 8.10), and water washing three times in the same order as in Example 1. The difference is that the entire process is carried out at room temperature (about 25°C) without heating. After each washing stage, add 0.1% nonionic polyacrylamide as a filter aid.

[0055] The iron content in the metatitanic acid obtained in this comparative example was 15.6 ppm, the sulfur content was 0.35%, and the TiO2 content after calcination was 98.40%.

[0056] Comparative Example 7 Take 100g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, and perform acid washing (acetic acid, pH 2.10, 50℃), alkali washing (ammonia water, pH 8.10, 50℃), and water washing three times (50℃) according to the steps in Example 1. The difference is that after each washing stage, no non-ionic polyacrylamide filter aid is added, and the filter is directly filtered.

[0057] Testing revealed that the iron content in the metatitanic acid obtained in this comparative example was 9.2 ppm, the sulfur content was 0.11%, and the TiO2 content after calcination was 98.80%. Filtration time determination: the average filtration time for each stage was approximately 2.5 times that of Example 1, and the moisture content of the filter cake was about 8 percentage points higher than that of Example 1.

[0058] Comparative Example 8 Take 70g of the same batch of sulfuric acid-washed metatitanic acid filter cake as in Example 1, and disperse it in a 2% sodium carbonate aqueous solution at a solid-liquid ratio of 70g:1L. After stirring at room temperature for 10 minutes, filter and wash with a 2% sodium carbonate solution until no SO4 is visible. 2- Ions are present; the obtained filter cake is slurried and dispersed in a 0.05 mol / L dilute hydrochloric acid aqueous solution, stirred at room temperature for 10 min, filtered, and washed with a 0.05 mol / L dilute hydrochloric acid solution until no CO3 is present. 2- Iron ions are present; finally, wash with water until the filtrate is neutral.

[0059] Testing revealed that the iron content in the metatitanic acid obtained in this comparative example was 4.8 ppm, the sulfur content was 9.5 ppm, and the TiO2 content after calcination was 99.50%. Ion chromatography and inductively coupled plasma atomic emission spectrometry analysis showed that the residual chloride ion content in the product was 92 ppm and the residual sodium ion content was 135 ppm.

[0060] Experimental Example 1 Effect of pickling pH on impurity removal efficiency: With fixed alkaline washing conditions (ammonia water, pH 8.10, 50℃) and water washing conditions (50℃, three times, 0.1% NPAM), the pickling pH was varied to investigate its effect on impurity removal efficiency. The results are shown in Table 1.

[0061] Table 1. Effect of pickling pH on the purification effect of metatitanic acid

[0062] The results showed that the pickling pH range of 2.00 to 2.20 had a better iron removal effect. Too low a pH (1.80) may cause partial gelation of metatitanic acid, while too high a pH (≥2.40) will reduce the iron removal effect.

[0063] Experiment Example 2 Effect of pH on impurity removal efficiency of alkaline washing: With fixed acid washing conditions (acetic acid, pH 2.10, 50℃) and water washing conditions (50℃, three times, 0.1% NPAM), the pH of alkaline washing was varied to investigate its effect on impurity removal efficiency. The results are shown in Table 2 below.

[0064] Table 2. Effect of alkaline washing pH on the purification effect of metatitanic acid

[0065] The results showed that alkaline washing had a better desulfurization effect in the pH range of 8.00 to 9.00. Desulfurization was incomplete when the pH was too low (7.50) and particle agglomeration may occur when the pH was too high (≥10.00).

[0066] Example 3 Effect of washing temperature on impurity removal efficiency: With fixed acid washing conditions (acetic acid, pH 2.10), alkaline washing conditions (ammonia, pH 8.10), and three water washes (0.1% NPAM), the washing temperature was varied to investigate the effect of temperature on impurity removal efficiency. The results are shown in Table 3.

[0067] Table 3. Effect of washing temperature on the impurity removal effect of metatitanic acid

[0068] The results showed that as the washing temperature increased from room temperature to 60℃, the removal efficiency of iron and sulfur improved significantly; further increasing the temperature to 70℃ did not significantly improve the removal efficiency and increased energy consumption.

[0069] Experiment Example 4 Effect of filter aid dosage on filtration performance: Under fixed acid washing conditions (acetic acid, pH 2.10, 50℃), alkaline washing conditions (ammonia, pH 8.10, 50℃), and water washing conditions (50℃, three times), the dosage of nonionic polyacrylamide was varied to investigate the effect of filter aid on filtration performance and product purity. The results are shown in Table 4.

[0070] Table 4. Effects of Filter Aid Dosage on Filtration Performance and Product Purity

[0071] The results showed that adding nonionic polyacrylamide could significantly shorten the filtration time and reduce the moisture content of the filter cake. The addition amount was effective in the range of 0.05% to 0.2%, with 0.1% being the preferred addition amount.

[0072] Experimental Example 5 Process stability verification of different batches of raw materials: Three different batches of sulfuric acid-washed metatitanic acid filter cake were used as raw materials, and impurity removal was performed according to the method in Example 1 to examine the batch stability and general applicability of the process. The results are shown in Table 5.

[0073] Table 5 Comparison of impurity removal effects of different batches of raw materials

[0074] The results show that the method of the present invention has a stable and excellent impurity removal effect on different batches of metatitanic acid raw materials, and the process has good versatility.

[0075] Experimental Example 6 Figure A shows a comparison of the appearance of the products after calcination: The purified metatitanic acid filter cakes obtained in Example 1 and Comparative Example 8 were calcined at 850℃ for 2 hours, and the appearance of the titanium dioxide products after calcination was observed. The results are as follows: Example 1: The product after calcination is a white powder with uniform color and no abnormal particles; The product of Comparative Example 8 after calcination is shown in Figure B below. It is light yellow with a small number of black spots on the surface.

[0076] The results showed that residual chloride ions may cause the product to turn yellow and develop black spots on the surface during high-temperature calcination; however, the present invention uses acetic acid and ammonia as detergents, which avoids the introduction of chloride and sodium ions, and the product after calcination is pure white and of excellent quality.

[0077] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for removing impurities from high-purity metatitanic acid, characterized in that, The method includes the following steps: Step 1, pickling step After adjusting the pH of the metatitanic acid raw material solution with pickling solution, pickling is performed. The pickling solution is an acetic acid solution, and the pickling temperature is 50-60℃. Step 2, Alkali Washing Step The acid-washed metatitanic acid is mixed with an alkaline washing solution, which is an ammonia solution, and the pH of the system is adjusted to 8-10. Step 3, water washing step The metatitanic acid, after being washed with alkali, was then washed with water.

2. The method for removing impurities from high-purity metatitanic acid according to claim 1, characterized in that, In step one, the metatitanic acid raw material solution is prepared by adding metatitanic acid raw material to water and dispersing it into a slurry, with the pH of the slurry system between 2.20 and 2.

50.

3. The method for removing impurities from high-purity metatitanic acid according to claim 1, characterized in that, Adjust the pH of the metatitanic acid feed solution to 2.10-2.20 using pickling solution.

4. The method for removing impurities from high-purity metatitanic acid according to claim 1, characterized in that, In step two, the alkaline washing temperature is 50–60°C.

5. The method for removing impurities from high-purity metatitanic acid according to claim 1, characterized in that, The method also includes a filtration step after the acid washing step, the alkali washing step, and the water washing step, namely, filtration after acid washing, filtration after alkali washing, and filtration after water washing.

6. The method for removing impurities from high-purity metatitanic acid according to claim 4, characterized in that, In the filtration step, a filter aid is added to the metatitanic acid slurry.

7. The method for removing impurities from high-purity metatitanic acid according to claim 5, characterized in that, The filter aid is nonionic polyacrylamide.

8. The method for removing impurities from high-purity metatitanic acid according to claim 6, characterized in that, The amount of nonionic polyacrylamide added is 0.05% to 0.2% of the mass of metatitanic acid.

9. The method for removing impurities from high-purity metatitanic acid according to claim 1, characterized in that, In the water washing step, in step three, the water washing temperature is 50-60℃, and the number of water washing cycles is three.

10. The method for removing impurities from high-purity metatitanic acid according to claim 1, characterized in that, In the water washing step, in step three, the washing endpoint is defined as the pH of the filtrate after washing being neutral.

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