CN117819598A - A method for preparing high-purity titanium dioxide - Google Patents

Abstract

The invention discloses a method for preparing high-purity titanium dioxide, comprising the following steps: S1. slowly mixing titanium tetrachloride with a hydrochloric acid aqueous solution to react and obtain a primary hydrolysis material containing titanium dichloride and hydrochloric acid; S2. mixing the primary hydrolysis material with water at 90-110°C for secondary hydrolysis, and separating the solid and liquid after hydrolysis to obtain a metatitanic acid precursor; S3. calcining the metatitanic acid precursor to obtain high-purity titanium dioxide. The present application first directly mixes titanium tetrachloride with a hydrochloric acid aqueous solution under conditions of limited concentration and dosage at room temperature to generate a mixed solution of titanium dichloride and hydrochloric acid, and then performs secondary hydrolysis on the mixed solution of titanium dichloride and hydrochloric acid under limited high temperature conditions. Compared with direct hydrolysis of titanium tetrachloride aqueous solution, this hydrolysis process does not need to react under low temperature conditions, has fewer intermediate products, is easy to control, and is fully hydrolyzed with a hydrolysis rate of more than 99.0%.

Description

A method for preparing high-purity titanium dioxide

Technical Field

The invention belongs to the technical field of titanium dioxide preparation, and specifically relates to a method for preparing high-purity titanium dioxide.

Background technique

Titanium dioxide, also known as titanium dioxide, is an important inorganic chemical raw material and is known as the "king of white pigments". It mainly has three crystal forms: rutile, anatase and brookite. It is non-toxic, has the best opacity, whiteness and brightness. It is considered to be the best performing white pigment in the world and is widely used in coatings, plastics, papermaking, inks, chemical fibers, ceramics, daily chemicals, capacitors, photocatalysis and other fields.

Titanium dioxide can be divided into pigment grade and non-pigment grade. Pigment grade mainly uses its white color, while non-pigment products mainly use its function and purity. Non-pigment grade titanium dioxide can also be divided into enamel grade titanium dioxide, welding rod grade titanium dioxide, ceramic grade titanium dioxide, electronic grade titanium dioxide and other types. High-purity titanium dioxide belongs to non-pigment grade.

Titanium dioxide is an inorganic substance with stable physical and chemical properties. It also has semiconductor properties, high dielectric constant and resistivity, and excellent mechanical and electrical properties. In recent years, titanium dioxide has gradually been valued in high-end manufacturing, electronic components, catalysts and other related fields due to its excellent photochemical properties. In these fields, high-purity titanium dioxide materials are widely used in electronic components: resistors (thermistors, varistors VDR), capacitors (chip multilayer ceramic capacitors MLCC), inductors, piezoelectrics (piezoelectric ceramics), circuit boards, integrated circuits, etc.; battery materials: lithium battery lithium titanate negative electrode, lithium battery titanium dioxide negative electrode, lithium battery positive electrode material additives, sodium ion battery negative electrode, fuel cell diaphragm, solar cell, etc.; glass: glass additives, glass colorants, optical glass, microcrystalline glass, special glass, etc. and titanium dioxide thin films: vacuum sputtering coating, vacuum evaporation coating, etc., so the preparation method of higher purity titanium dioxide is becoming the mainstream research object, and the demand has increased year by year in recent years.

High-purity _TiO2 generally refers to _TiO2 with a purity of 99.0-99.9%. The higher the purity of titanium dioxide, _the better the performance and more stable the quality of the products made with it as raw material. Harmful impurities in titanium dioxide will have an adverse effect on subsequent finished products, especially elements such as silicon, aluminum, and iron, which have a fatal impact on the quality of finished products.

At present, the production methods of high-purity titanium dioxide in China mainly include sulfuric acid method, TiCl ₄ direct hydrolysis method, chlorination method and titanium alcohol salt hydrolysis method. The sulfuric acid method for preparing high-purity titanium dioxide has the advantages of simple and mature process, easy raw materials, low cost and simple equipment, but the preparation system itself has high impurity content and introduces other impurities, which makes the product purity low. The direct hydrolysis method of titanium tetrachloride has a short process flow and good product quality, but the raw material quality requirements are high and the production cost is high. At the same time, a large amount of acid-containing wastewater is generated during the production process, which puts huge pressure on environmental protection. The chlorination method has a short process flow, a high degree of automation, less "three wastes", and good product quality, but there are problems such as high technical difficulty, high raw material quality requirements, and strict equipment material requirements, and it is difficult to industrialize. The titanium dioxide prepared by the titanium alcohol hydrolysis method has high purity, small particle size, and narrow particle size distribution, but the cost of titanium alcohol salt is too high and is only suitable for laboratory production.

Patent CN103073058A directly adds titanium tetrachloride to water to prepare titanium tetrachloride solution, then adds hydrochloric acid and deionized water to the titanium tetrachloride solution to prepare a mixed solution, and then obtains rutile nano titanium dioxide powder with a particle size of 15 to 30 nm through hydrolysis, filtration, washing, vacuum drying, etc. Since TiCl ₄ is extremely active and easily hydrolyzed, it will form smoke with water vapor in the air. The reaction between TiCl ₄ and water is violent and complex. TiCl ₄ is slowly added to water to first generate a white suspension. Then, as TiCl ₄ continues to be added, the acidity in the reaction solution increases, the suspension dissolves, and titanium tetrachloride is continued to be added to obtain a yellow-green liquid. The reaction is affected by temperature and the ratio of titanium tetrachloride to water. The ratio of titanium tetrachloride to water needs to be controlled within a certain range to obtain a solution. The reaction process is not easy to control, and since the process does not perform endpoint pH adjustment and calcination treatment, the titanium dioxide obtained has a hard particle size and mixed crystal forms.

The document "Zhou Zhongcheng, et al. Direct preparation of rutile nano-titanium dioxide by low-temperature hydrolysis of titanium tetrachloride. [J] Rare Metals, 2006, 30 (5): 653-65" is prepared by first preparing a mixture of isopropanol and water, then adjusting the pH value with hydrochloric acid, then slowly adding titanium tetrachloride solution, and adding ammonia water to adjust the pH value, then hydrolyzing at 70°C for 3h, aging for 24h, filtering, washing with anhydrous ethanol 2-3 times, and drying at 80°C to obtain _TiO2 powder. Then calcining at 300 and 400°C for 2h to obtain the sample. This method hydrolyzes under alkaline conditions, and the hydrolysis reacts instantly. The reaction is not easy to control. The prepared sample grain size and its distribution are not easy to control, the specific surface area is too large, the downstream application reaction activity is not easy to control, and the purity of titanium dioxide is also low, which needs further improvement.

Therefore, it is of great significance to develop a method for producing high-purity titanium dioxide that is easy to control.

Summary of the invention

The purpose of the present invention is to provide a method for preparing high-purity titanium dioxide in order to solve the deficiencies of the prior art.

The objective of the present invention is achieved by the following technical solutions:

A method for preparing high-purity titanium dioxide comprises the following steps:

S1. Slowly mixing titanium tetrachloride with an aqueous hydrochloric acid solution to obtain a primary hydrolysis material containing titanium dichloride and hydrochloric acid; the mass fraction of the aqueous hydrochloric acid solution is 18 to 22%, and the mass ratio of the titanium tetrachloride to the aqueous hydrochloric acid solution is (0.4 to 0.8): 1;

S2. The primary hydrolyzate is mixed with water and subjected to secondary hydrolysis at 90 to 110°C, and solid-liquid separation is performed after hydrolysis to obtain a metatitanic acid precursor; the volume ratio of the primary hydrolyzate to the water is 1:(1.5 to 2.5);

S3. calcining the metatitanate precursor to obtain high-purity titanium dioxide.

Preferably, the purity of the titanium tetrachloride is ≥99.99%.

Preferably, the titanium tetrachloride is crude titanium tetrachloride obtained by chlorination and condensation in a conventional chlorination process, and then purified by distillation; the distillation temperature is 130-160°C.

Preferably, after mixing in step S1, the mixture is allowed to stand for reaction for 0.5 to 1 hour, and the concentration of the primary hydrolysis material is 250 to 450 g/L in terms of _TiO2 .

Preferably, in step S2, the primary hydrolysis material is slowly added into water for 2 to 5 hours, and the material is kept warm and homogenized for 0.5 to 2 hours after the addition.

Preferably, after the hydrolysis in step S2, the metatitanate precursor is prepared by the following method:

First, the first solid-liquid separation is performed, the filter cake is re-slurried by adding water, and the pH is adjusted to 6.0-8.0;

Then, a secondary solid-liquid separation is performed, and water washing and alcohol washing are used in sequence to obtain the metatitanic acid precursor.

Preferably, the filtrate from the first solid-liquid separation is recycled to step S1 for recycling.

Preferably, the pH is adjusted using aqueous ammonia.

Preferably, the calcination temperature in step S3 is 550-750° C. and the calcination time is 2.0-5.0 h.

Preferably, in step S3, the metatitanate precursor is placed in a calcining furnace and then calcined under programmed temperature conditions, wherein the programmed temperature conditions are:

Stage 1: Raise the temperature from room temperature to 185-215°C within 15-25 minutes;

The second stage: the temperature is raised from 185-215°C to 550-750°C within 50-60 minutes;

The third stage: then keep warm at 550-750℃ for 2.0-5.0h.

The present invention first directly reacts titanium tetrachloride with a hydrochloric acid aqueous solution under conditions of limited concentration and dosage at room temperature to generate a mixed solution of titanium dichloride and hydrochloric acid, and then the mixed solution of titanium dichloride and hydrochloric acid is subjected to secondary hydrolysis under limited high temperature conditions, and titanium dichloride is directly hydrolyzed into metatitanic acid at one time. Compared with direct hydrolysis of titanium tetrachloride aqueous solution, the hydrolysis process does not need to react under low temperature conditions, has fewer intermediate products, is easy to control, and titanium dichloride is fully hydrolyzed, with a hydrolysis rate of more than 99.0%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an electron microscope scanning image of a certain grade of commercially available high-purity titanium dioxide;

FIG. 2 is an electron microscope scanning image of the high-purity titanium dioxide obtained in Example 3.

Detailed ways

The present invention provides a method for preparing high-purity titanium dioxide, comprising the following steps:

S1. Take titanium tetrachloride and slowly mix it with hydrochloric acid aqueous solution to obtain a primary hydrolysis material containing titanium dichloride and hydrochloric acid; the mass fraction of the hydrochloric acid aqueous solution is 18-22%, and the mass ratio of titanium tetrachloride to the hydrochloric acid aqueous solution is (0.4-0.8):1; when the amount of hydrochloric acid used is too much, the acidity of the primary hydrolysis material and the secondary hydrolysis material is too high, and too much alkali is required to neutralize the material before subsequent calcination. When the amount of hydrochloric acid used is too little, the primary hydrolysis will generate a white precipitate, which affects the subsequent hydrolysis.

If a white complex is produced by the first hydrolysis and then a second hydrolysis is performed, the white complex is equivalent to the addition of seed crystals. The hydrolysis process will cause deposition around the white complex. The grain size and distribution of the prepared sample will become larger, affecting the application performance of the sample prepared later.

S2. The primary hydrolyzate is mixed with water and subjected to secondary hydrolysis at 90 to 110°C, and solid-liquid separation is performed after hydrolysis to obtain a metatitanate precursor; the volume ratio of the primary hydrolyzate to water is 1:(1.5 to 2.5);

Secondary hydrolysis ensures that there is enough reactant water, which is beneficial for the reaction to proceed to the right, and the hydrolysis rate will increase accordingly.

S3. calcining the titanate precursor to obtain high-purity titanium dioxide.

In the prior art, titanium tetrachloride is hydrolyzed to prepare titanium dioxide. Titanium tetrachloride is first dissolved in water at a low temperature of less than 10°C to prepare a titanium tetrachloride aqueous solution, and then the titanium tetrachloride aqueous solution is mixed with hydrochloric acid for hydrolysis. However, titanium tetrachloride is easy to react with water in general, and the reaction is complicated, with more intermediate products. White complexes are easily generated in the process of preparing titanium tetrachloride aqueous solution. The reaction is affected by the ratio of titanium tetrachloride to water. The formation of white complexes makes it difficult to control the grain size and distribution of the hydrolyzed material. The specific surface area of the obtained product is large. Since the reaction is affected by water, insufficient water will lead to a decrease in the hydrolysis rate. If titanium tetrachloride is directly hydrolyzed, a white complex will be generated when there is too much water. However, using titanium dichloride for secondary hydrolysis, using enough water will increase the hydrolysis rate and hydrolysis rate.

The present application first directly mixes titanium tetrachloride with a hydrochloric acid aqueous solution under conditions of limited concentration and dosage at room temperature to generate a mixed solution of titanium dichloride and hydrochloric acid. It has been verified by experiments that under the conditions specified in the present application, titanium tetrachloride reacts with the hydrochloric acid aqueous solution to directly generate a yellow-green mixed solution of titanium dichloride and hydrochloric acid, and no white complex is generated. It is speculated that the presence of the initial hydrochloric acid aqueous solution prevents the formation of the complex; and then the mixed solution of titanium dichloride and hydrochloric acid is subjected to secondary hydrolysis under limited high temperature conditions, and titanium dichloride is directly hydrolyzed into metatitanic acid at one time. The reaction formula involved in the secondary hydrolysis is mainly as follows:

TiOCl ₂ +2H ₂ O→TiO(OH) ₂ ↓+2HCl

At the beginning of hydrolysis, the free acid concentration in the solution is low. Under high temperature conditions, it is beneficial for the hydrolysis reaction to proceed in the positive direction, so the hydrolysis rate is fast. As the reaction proceeds, the free acidity in the hydrolyzate increases, the concentration of the product HCl increases, and the inhibitory effect on the positive reaction becomes greater, which effectively controls the reaction rate, so that titanium dichloride is gradually and fully hydrolyzed, metatitanic acid is uniformly precipitated, the particle size and particle size morphology are effectively controlled, and the hydrolysis rate is improved. In order to prevent the reaction rate from being slow, sufficient water is required for the secondary hydrolysis to carry out the hydrolysis reaction, which can accelerate the hydrolysis reaction rate, promote the hydrolysis of TiOCl ₂ , and improve the hydrolysis rate.

Compared with direct hydrolysis of titanium tetrachloride aqueous solution, the hydrolysis process does not need to react under low temperature conditions, has fewer intermediate products, is easy to control, and fully hydrolyzes titanium dichloride with a hydrolysis rate of more than 99.0%.

The purity of titanium dioxide can be improved by using titanium tetrachloride with higher purity. The purity of titanium tetrachloride in the present application is preferably ≥ 99.99%. Further preferably, crude titanium tetrachloride obtained by chlorination and condensation through a conventional chlorination process is purified by distillation to obtain high-purity titanium tetrachloride, and the distillation temperature is 130-160°C.

Preferably, after mixing in step S1, the mixture is allowed to react for 0.5 to 1 hour. Titanium tetrachloride will volatilize to a certain extent during hydrolysis, and the titanium in the obtained primary hydrolysis material is lower than the initial amount of titanium tetrachloride. The concentration of the primary hydrolysis material is 250 to 450 g/L in terms of _TiO2 .

Preferably, in step S2, the primary hydrolysis material is slowly added into water for 2 to 5 hours, and the material is kept warm and homogenized for 0.5 to 2 hours after the addition to make the reaction more thorough.

Preferably, after the hydrolysis in step S2, a metatitanate precursor is prepared by the following method:

First, the first solid-liquid separation is performed, preferably by pressing separation, the filter cake is re-pulped with water, and the pH is adjusted to 6.0-8.0, which is conducive to calcination under neutral conditions, and the calcined material is relatively fluffy; the filtrate of solid-liquid separation is recycled to step S1 for recycling, and the hydrochloric acid therein can be recovered to save production costs; ammonia water is preferably used for pH adjustment;

Then, a secondary solid-liquid separation is performed, and water washing and alcohol washing are used in sequence to obtain a metatitanic acid precursor. Alcohol washing is performed after water washing to reduce surface tension and make the calcined material soft.

The calcination temperature in step S3 is 550-750° C. and the calcination time is 2.0-5.0 h.

Step S3: placing the metatitanate precursor in a calcining furnace, and then calcining it under programmed temperature conditions, wherein the programmed temperature conditions are:

Stage 1: Raise the temperature from room temperature to 185-215°C within 15-25 minutes;

The second stage: the temperature is raised from 185-215°C to 550-750°C within 50-60 minutes;

The third stage: then keep warm at 550-750℃ for 2.0-5.0h.

By adjusting the calcination temperature and time, titanium dioxide with different crystal forms and specific surface areas can be obtained. The appropriate calcination temperature and time can be selected according to the requirements of downstream customers. Generally speaking, the higher the calcination temperature, the higher the rutile conversion rate.

The method provided by the invention has short flow, simple steps, low cost, high production efficiency, and no additional substances are introduced in the whole production process. The obtained titanium dioxide has low impurity content and high product purity, _TiO2≥99.5 %, BET is ^15-25m2 /g, and according to the XRD analysis result, the average particle size calculated by using Scherrer equation is about 68nm.

Example 1

The crude titanium tetrachloride prepared by chlorination and condensation of titanium-rich material and petroleum coke by conventional chlorination process is then purified by distillation at 140°C to obtain high-purity titanium tetrachloride with a purity of 99.99%; concentrated hydrochloric acid with a mass fraction of 36% is diluted with water to prepare a hydrochloric acid solution with a mass ratio of 1:1; the distilled titanium tetrachloride is slowly added to the 1:1 hydrochloric acid solution within 3 hours to make m _TiCl4 :m _{1:1HCl solution} = 0.4:1, then stand and react for 30 minutes to obtain a primary hydrolysis material; then add the primary hydrolysis material into boiling water within 2 hours for secondary hydrolysis, V _water : V _{primary hydrolysis material} = 1.7:1, and then keep it warm at 100°C for 0.5h to obtain a secondary hydrolysis material; after the secondary hydrolysis material is squeezed, the filter cake is re-pulped with water, and ammonia water is added to adjust the pH to 7.0; secondary squeezing is performed and washed with water to a conductivity of 50μs/cm, and then washed twice with ethanol; after flash drying, the filter cake is loaded into a clean sagger and calcined in an air atmosphere at a calcination temperature of 600°C for 2.5h, then naturally cooled to room temperature, and crushed to obtain high-purity titanium dioxide powder.

Example 2

The crude titanium tetrachloride prepared by chlorinating and condensing the titanium-rich material and petroleum coke through a conventional chlorination process is then purified by distillation at 150°C to obtain high-purity titanium tetrachloride with a purity of 99.999%; concentrated hydrochloric acid with a mass fraction of 37% is diluted with water to prepare a hydrochloric acid solution with a mass ratio of 1:1; the distilled titanium tetrachloride is slowly added to the 1:1 hydrochloric acid solution within 2 hours to make m _TiCl4 :m _{1:1HCl solution} = 0.5:1, then stand and react for 60 minutes to obtain a primary hydrolysis material; then add the primary hydrolysis material into boiling water within 3 hours for secondary hydrolysis, V _water : V _{primary hydrolysis material} = 2.0:1, and then keep it at 105°C for 1.0h to obtain a secondary hydrolysis material; after the secondary hydrolysis material is squeezed, the filter cake is re-pulped with water, and ammonia water is added to adjust the pH to 7.1; secondary squeezing is performed and washed with water to a conductivity of 45μs/cm, and then washed with ethanol 3 times; after flash drying, the filter cake is loaded into a clean sagger and calcined in an air atmosphere at a calcination temperature of 650°C for 3.0h, then naturally cooled to room temperature, and crushed to obtain high-purity titanium dioxide powder.

Example 3

The crude titanium tetrachloride prepared by chlorination and condensation of titanium-rich material and petroleum coke by conventional chlorination process is then purified by distillation at 155°C to obtain high-purity titanium tetrachloride with a purity of 99.9995%; concentrated hydrochloric acid with a mass fraction of 37% is diluted with water to prepare a hydrochloric acid solution with a mass ratio of 1:1; the distilled titanium tetrachloride is slowly added to the 1:1 hydrochloric acid solution within 2 hours to make m _TiCl4 :m _{1:1HCl solution} = 0.57:1 to obtain a primary hydrolysis material; then the primary hydrolysis material is added into boiling water within 3 hours for secondary hydrolysis, _Vwater : _{Vprimary hydrolysis material} = 2.5:1, and then kept warm at 105°C for 1.0h to obtain a secondary hydrolysis material; after the secondary hydrolysis material is squeezed, the filter cake is re-pulped with water, and ammonia water is added to adjust the pH to 7.2; secondary squeezing is performed and washed with water to a conductivity of 43μs/cm, and then washed with ethanol for 3 times; after flash drying, the filter cake is loaded into a clean sagger and calcined in an air atmosphere at a calcination temperature of 700°C for 3.0h, then naturally cooled to room temperature, and crushed to obtain high-purity titanium dioxide powder.

Comparative Example 1

First, at 10°C, titanium tetrachloride is added to stirred deionized water at a rate of 40 ml/h to prepare a titanium tetrachloride solution with a concentration of 2 mol/L, and then the temperature is raised to 100°C. After hydrolysis for 3 hours, a titanic acid gel is obtained, which is then pumped into a filter press for filtration; the titanic acid filter cake obtained by filtration is placed in a kiln for calcination, the calcination temperature is controlled to be 650°C, and after constant temperature calcination for 3 hours, it is taken out to obtain titanium dioxide powder.

Comparative Example 2

First, at 10°C, titanium tetrachloride is added to stirred deionized water at a rate of 40 mL/h to prepare a titanium tetrachloride solution with a concentration of 2 mol/L. Then, a total volume of 950 ml of hydrochloric acid (hydrogen ion concentration of 6.3 mol/L) and deionized water are added to the titanium tetrachloride solution with a concentration of 2 mol/L and a volume of 50 mL to prepare a mixed solution with a titanium ion concentration of 0.1 mol/L and a hydrogen ion concentration of 6 mol/L. The mixed solution is then hydrolyzed at 110°C for 3 hours to obtain a precipitate. The precipitate is filtered, washed, dried, and calcined at 650°C for 3 hours to obtain rutile nano-titanium dioxide.

The comparison of some indicators of the titanium dioxide prepared in the embodiment of the present invention, a commercially available high-purity titanium dioxide with better quality, and the titanium dioxide prepared in Comparative Examples 1-2 is shown in Table 1, and the particle morphology is shown in Figures 1 and 2.

Table 1

It can be seen from the above data that the titanium dioxide prepared by the present invention has better TiO ₂ %, BET, particle size and impurity content than the commercially available products and comparative examples 1-2, and the particle morphology of the product prepared by the present invention is more uniform.

Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (10)

1. The preparation method of the high-purity titanium dioxide is characterized by comprising the following steps of:

s1, slowly mixing titanium tetrachloride with a hydrochloric acid aqueous solution, and reacting to obtain a primary hydrolysate containing titanium oxychloride and hydrochloric acid; the mass fraction of the hydrochloric acid aqueous solution is 18-22%, and the mass ratio of the titanium tetrachloride to the hydrochloric acid aqueous solution is (0.4-0.8): 1;

s2, mixing the primary hydrolysis material with water to carry out secondary hydrolysis at the temperature of 90-110 ℃, and carrying out solid-liquid separation after the hydrolysis to obtain a metatitanic acid precursor; the volume ratio of the primary hydrolysis material to the water is 1 (1.5-2.5);

s3, calcining the metatitanic acid precursor to obtain the high-purity titanium dioxide.

2. The method for producing high purity titanium dioxide according to claim 1,

the purity of the titanium tetrachloride is more than or equal to 99.99 percent.

3. The method for producing high purity titanium dioxide according to claim 2,

the titanium tetrachloride is crude titanium tetrachloride obtained by chlorination and condensation through a conventional chlorination process, and is purified by rectification; the rectification temperature is 130-160 ℃.

4. The method for producing high purity titanium dioxide according to claim 1,

step S1, mixing, standing and reacting for 0.5-1 h, wherein the concentration of the primary hydrolysis material is TiO ₂ Accounting for 250 g/L to 450g/L.

5. The method for producing high purity titanium dioxide according to claim 1,

step S2, slowly adding the primary hydrolysis material into water, wherein the charging time is 2-5 h, and preserving heat and homogenizing for 0.5-2 h after charging.

6. The method for producing high purity titanium dioxide according to claim 1,

and step S2, preparing the metatitanic acid precursor by the following method after hydrolysis:

firstly, carrying out solid-liquid separation for the first time, adding water into a filter cake to re-pulp, and adjusting the pH value to 6.0-8.0;

and then carrying out secondary solid-liquid separation, and sequentially adopting water washing and alcohol washing to obtain the metatitanic acid precursor.

7. The method for producing high purity titanium dioxide according to claim 6,

and (3) recycling the filtrate obtained by the first solid-liquid separation to the step S1 for recycling.

8. The method for producing high purity titanium dioxide according to claim 6,

ammonia is used for pH adjustment.

9. The method for producing high purity titanium dioxide according to claim 1,

and step S3, wherein the calcining temperature is 550-750 ℃ and the calcining time is 2.0-5.0 h.

10. The method for producing high purity titanium dioxide according to claim 9,

step S3, placing the metatitanic acid precursor in a calciner, and calcining under the temperature programming condition:

the first stage: raising the temperature from room temperature to 185-215 ℃ within 15-25 min;

and a second stage: raising the temperature from 185 ℃ to 215 ℃ to 550 ℃ to 750 ℃ within 50 min to 60 min;

and a third stage: then preserving heat for 2.0-5.0 h at 550-750 ℃.