Titanium liquid hydrolysis method, metatitanic acid particles and titanium dioxide

Abstract

The present invention discloses a titanium liquid hydrolysis method and metatitanic acid particles, which comprises the following steps: S1, adding orthotitanic acid nuclei to titanium liquid B, stirring, heating and hydrolyzing, and keeping warm; S2, when the hydrolysis rate of titanium liquid B reaches 70-90%, continuing to heat up to boiling, and keeping warm to obtain metatitanic acid particles; wherein the mass concentration of the titanium liquid B is 22-28%, the stability K of the titanium liquid B is less than 500ml, and the final stability of the orthotitanic acid nuclei is 110ml. The present invention solves the problem of poor stability of orthotitanic acid nuclei prepared by titanium liquid with poor stability, reacts the titanium liquid with poor stability with sodium metaaluminate, and the orthotitanic acid nuclei prepared are active and stable. After adding the orthotitanic acid nuclei prepared by the present invention to the titanium liquid with poor stability, a regular crystallization, uniform particle size, and very little impurity content wrapped by metatitanic acid particles can be obtained, and the whiteness, tinting power and other properties of the obtained titanium dioxide finished product are excellent.

Description

Technical Field

[0001] The invention relates to the field of titanium dioxide production, in particular to a titanium liquid hydrolysis method, metatitanic acid particles and titanium dioxide, which are particularly suitable for hydrolyzing titanium liquid with poor stability. Background Art

[0002] The hydrolysis of titanium dioxide transforms the liquid titanium dioxide component into solid metatitanic acid, thereby separating it from soluble impurities in the mother liquor to extract pure titanium dioxide. The hydrolysis of titanium dioxide is a crucial step in the sulfuric acid process for titanium dioxide production. The quality of the hydrolysis process not only affects the economic viability of industrial production but also significantly impacts the quality of the final product.

[0003] Titanium liquid stability refers to the phenomenon in titanium dioxide production where, under changing conditions, the liquid undergoes premature hydrolysis, resulting in the precipitation of white metatitanic acid colloidal particles (TiO2). The strength of this phenomenon is called stability. Stability is an important indicator of titanium liquid quality.

[0004] The stability of titanium solution is expressed as the number of ml of distilled water required to dilute each ml of titanium solution with 25°C distilled water until white turbidity appears. The calculation is: Titanium solution stability (K) = Volume of distilled water used for titanium solution hydrolysis / Volume of titanium solution. For example, the number of ml of distilled water required to dilute 1 ml of titanium solution with 25°C distilled water until white turbidity appears is the stability of the titanium solution. Generally, the stability K of pigment-grade titanium dioxide hydrolyzed titanium solution is controlled to be above 500 ml. A K below 500 ml is considered to be poorly stable.

[0005] Unexpected production accidents often occur during the production of titanium dioxide: such as sudden power outages and equipment damage, which prevent normal and orderly production and prevent the titanium liquid from entering the next process in a timely manner. During long-term storage, the titanium liquid with poor stability will age and gradually precipitate colloidal TiO2 particles. For titanium liquid with poor stability, colloidal TiO2 particles are already produced before hydrolysis. These colloidal particles exist in the titanium liquid and form irregular crystal centers during hydrolysis. The size and shape of these irregular crystal centers are random and disordered. The resulting hydrated TiO2 particles are uneven and porous, easily absorbing a large number of impurities, affecting filtration and significantly extending washing time. During calcination, due to their irregularity, impurities such as sulfur and iron are coated in the hydrated TiO2 particles. The calcination temperature needs to be increased to completely remove impurities such as sulfur and iron. However, if the temperature is increased, the hydrated TiO2 particles are prone to sintering, hardening, and turning gray. Ultimately, the whiteness, tinting power, and other pigment properties of the finished titanium dioxide will be significantly reduced. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for hydrolyzing titanium liquid and metatitanic acid particles in view of the shortcomings of the existing technology, wherein the prepared metatitanic acid particles have a low impurity content.

[0007] The present invention also provides a titanium dioxide, and the whiteness, tinting power and other pigment properties of the titanium dioxide finished product are significantly improved.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a titanium liquid hydrolysis method, comprising the following steps:

[0009] S1. Add orthotitanate nuclei to titanium liquid B, stir, heat and hydrolyze, and keep warm;

[0010] S2. When the hydrolysis rate of titanium liquid B reaches 70-90%, continue to heat it to boiling and keep it warm to obtain metatitanate particles;

[0011] The mass concentration of the titanium liquid B is 22-28%, and the stability K of the titanium liquid B is less than 500 ml;

[0012] Stability of titanium liquid K = volume of distilled water used for titanium liquid hydrolysis / volume of titanium liquid;

[0013] The initial stability of the orthotitanic acid crystal nucleus is 160-170 ml, and the final stability of the orthotitanic acid crystal nucleus is 110 ml.

[0014] In the present invention, orthotitanic acid nuclei are added before heating when hydrolyzing titanium liquid B. In order to evenly mix the titanium liquid with poor stability with the orthotitanic acid nuclei with good activity and stability, the titanium liquid with poor stability and the orthotitanic acid nuclei are heated together. The activity of the orthotitanic acid nuclei is better than that of the titanium liquid with poor stability, thereby avoiding the formation of a small amount of inferior colloidal particles due to early hydrolysis before heating, thereby reducing the impurity content of the obtained metatitanic acid particles.

[0015] According to the activity principle, the prepared orthotitanate nuclei are preferably used when the titanium liquid B is hydrolyzed.

[0016] If the concentration of the titanium liquid is lower than 22%, the stability of the titanium liquid will be worse, and the titanium liquid will hydrolyze prematurely to form irregular titanate particles; if the concentration of the titanium liquid is higher than 28%, the concentration cost will increase.

[0017] Preferably, the temperature is maintained until the hydrolysis rate of titanium liquid B reaches 80-85%. If the hydrolysis rate of titanium liquid B with poor stability is less than 70%, titanium liquid B will hydrolyze at a boiling state, and the particle size of the hydrolyzed metatitanic acid particles will be too coarse, affecting the whiteness, tinting power and other properties of the finished titanium dioxide. If the hydrolysis rate of titanium liquid with poor stability is too high, the acidity will increase later, resulting in repeated dissolution of precipitated particles and an increase in precipitated particles, which will lead to a decrease in product quality.

[0018] In addition, the stability of titanium liquid K = the volume of distilled water used for hydrolysis of titanium liquid / the volume of titanium liquid, and the volume of distilled water used for hydrolysis of titanium liquid and the volume of titanium liquid are expressed in ml.

[0019] In a preferred embodiment of the present invention, the mass percentage of TiO2 in the orthotitanate crystal nuclei in S1 to the titanium liquid B is 0.5-0.7%.

[0020] If the amount of orthotitanic acid nuclei added is too low, there will be fewer crystallization centers, and the colloidal particles precipitated early in the titanium liquid B will act as the crystallization centers of the orthotitanic acid nuclei. The generated hydrated TiO2 particles will be uneven and have many pores, which will ultimately affect the whiteness, tinting power and other properties of the titanium dioxide product. If the amount of orthotitanic acid nuclei added is too high, the hydrolysis rate of the titanium dioxide liquid B will be accelerated, and the stability of the titanium dioxide itself is poor, resulting in the hydrolyzed particles being too coarse, affecting the pigment properties of the final titanium dioxide product.

[0021] In a preferred embodiment of the present invention, the stirring time in S1 is 8-15 minutes, preferably 8-10 minutes.

[0022] If the stirring time of S2 is too short, the orthotitanic acid crystal nuclei cannot be evenly dispersed in the titanium liquid B, which is not conducive to hydrolysis; if the stirring time of S2 is too long, it will accelerate the hydrolysis of the titanium liquid B with poor stability at low temperature, and the metatitanic acid particles formed will have a large pore size and adsorb more impurities, affecting the subsequent washing and calcination processes, and ultimately affecting the whiteness, decolorizing power and other properties of the titanium dioxide product.

[0023] In a preferred embodiment of the present invention, the temperature of the hydrolysis in S1 is 90-103°C;

[0024] According to the principles of crystallography, titanium liquid B uses orthotitanic acid nuclei as its crystallization center, grows on the surface of the orthotitanic acid nuclei, and then combines to form larger aggregates. The size of the aggregates depends on the composition of titanium liquid B and the hydrolysis conditions. Titanium liquid B, which has poor stability, is easily hydrolyzed under the guidance of orthotitanic acid nuclei. Therefore, we control the hydrolysis temperature of titanium liquid B below its boiling temperature (it needs to reach 105-106°C to boil) to control the hydrolysis rate, prevent rapid hydrolysis reaction, and obtain uniform hydrolyzed metatitanic acid particles.

[0025] The holding time in S1 is 20-40 minutes; the boiling time in S2 is 120-150 minutes.

[0026] In a preferred embodiment of the present invention, the method for preparing orthotitanate crystal nuclei comprises the following steps:

[0027] Titanium liquid A is added to a weakly alkaline compound and mixed evenly, and then heated, aged, and rapidly cooled to obtain orthotitanate crystal nuclei. The stability K of the titanium liquid A is less than 500 mL.

[0028] In a preferred embodiment of the present invention, the mass concentration of the titanium liquid A is 22-28%, preferably the mass concentration of the titanium liquid A is 24-26%.

[0029] If the concentration of the titanium liquid is lower than 22%, the stability of the titanium liquid will be worse, and the titanium liquid will hydrolyze prematurely to form irregular titanate particles; if the concentration of the titanium liquid is higher than 28%, the concentration cost will increase.

[0030] In a preferred embodiment of the present invention, the weakly alkaline compound in S1 is sodium metaaluminate, and the mass concentration is 1-8%, preferably 3-5%.

[0031] If the concentration of sodium aluminate is lower than 1%, the reaction time between it and titanium liquid A is long, and fewer orthotitanic acid nuclei are formed, which will reduce the concentration of titanium liquid A, prompting the hydrolysis of titanium liquid A, forming more irregular crystal centers, and causing the formed orthotitanic acid nuclei to be irregular; if the concentration of sodium aluminate is higher than 8%, the particle size of the orthotitanic acid nuclei obtained after the reaction with titanium liquid A is relatively fine, which is not conducive to the water washing of the hydrolyzed orthotitanic acid.

[0032] For titanium liquid with poor stability, the existing seed crystal preparation process is used to heat and mature the titanium liquid with a strong base to produce orthotitanic acid nuclei. The addition of a strong base to the titanium liquid with poor stability reacts extremely quickly, releasing a large amount of heat in a short period of time. The poorly stable titanium liquid will hydrolyze at high temperatures, which inevitably accelerates the hydrolysis process and forms a large number of irregular crystal centers. The size and shape of these irregular crystal centers are random and disordered. The resulting hydrated TiO2 particles are uneven and porous, easily absorbing a large number of impurities, affecting filtration and significantly extending washing time. During calcination, due to their irregularity, impurities such as sulfur and iron are encapsulated in the hydrated TiO2 particles. The calcination temperature needs to be increased to completely remove these impurities. However, if the temperature is increased, the hydrated TiO2 particles tend to sinter, harden, and turn gray. Ultimately, the whiteness, tinting power, and other pigment properties of the finished titanium dioxide product will be significantly reduced.

[0033] In the present invention, the sodium metaaluminate selected is a weak base and will not react with the poorly stable titanium liquid to increase the temperature as quickly as a strong base.

[0034] The initial stability of orthotitanic acid nuclei prepared by reacting a stable titanium liquid with an alkali is typically 160-170 ml, allowing the hydrolysis process to proceed normally. However, in the present invention, when a titanium liquid with poor stability is used, the orthotitanic acid nuclei prepared by the reaction after the addition of a strong alkali have poor activity and stability of less than 80 ml, making the generated orthotitanic acid nuclei unfavorable for subsequent hydrolysis. In a preferred embodiment of the present invention, the orthotitanic acid nuclei prepared by reacting a titanium liquid with poor stability with sodium metaaluminate have an initial stability of 160-170 ml, and the final stability of the orthotitanic acid nuclei after aging is 110 ml.

[0035] In a preferred embodiment of the present invention, the weight ratio of the titanium liquid A to the weakly basic compound in S1 is (250-550):(4-300);

[0036] If the weight ratio of titanium liquid A to the weakly alkaline compound is too high, the acidity will be high, the seed crystals will be highly stable, and the seed crystals will be less active. If the weight ratio is too low, the acidity will be low, and the stability of titanium liquid A itself will be poor, resulting in poor stability and activity of the prepared orthotitanic acid nuclei, which will be detrimental to hydrolysis and lead to poor hydrolysis results. If the amount of weakly alkaline compound is small, the number of prepared orthotitanic acid nuclei will be small. During the hydrolysis process, the poorly stable titanium liquid will form irregular crystal centers, which will become irregular orthotitanic acid nuclei and participate in the process. This can easily lead to irregular and defective metatitanic acid hydrolyzed particles formed during the hydrolysis process.

[0037] In the present invention, sodium metaaluminate is a weak base and is added to the titanium liquid with poor stability without heating in order to avoid the precipitation of irregular crystal centers in the titanium liquid when heated, thereby ensuring the activity of preparing orthotitanic acid crystal nuclei.

[0038] The temperature in S1 is raised to 35-45°C, and the curing time in S1 is 5-15 minutes;

[0039] If the aging time is too short, fewer orthotitanic acid nuclei will be formed and their activity will be low. As the aging time increases, the activity of the orthotitanic acid nuclei will increase to an acceptable range. At this time, since the dissolution and precipitation of the generated orthotitanic acid nuclei is a dynamic process, when the total amount and size changes of the orthotitanic acid nuclei tend to be stable, the orthotitanic acid nuclei can reach a relatively uniform state, and the titanium dioxide product with a blue base phase and high tinting power can also be achieved. If the aging time is too long, the orthotitanic acid seed solution will easily hydrolyze prematurely.

[0040] In the method for preparing orthotitanate crystal nuclei, the temperature after cooling is below 25°C;

[0041] In the present invention, the seed crystals are cooled to below 25° C. after preparation. At this temperature, the activity and stability of the seed crystals are the best, which is conducive to the subsequent hydrolysis process.

[0042] The addition rate of the titanium liquid A is 250-550 g / min, and the addition rate of the titanium liquid A is from slow to fast.

[0043] Titanium liquid is generally added to the weakly alkaline compound at a rate that starts slowly and then increases rapidly. The purpose is to ensure that titanium liquid A and the weakly alkaline compound form orthotitanate nuclei of relatively uniform volume and size. If titanium liquid A is added to the weakly alkaline compound for too short a time, orthotitanate nuclei will form rapidly and in large quantities, causing the saturation in the titanium liquid to decrease rapidly. At the same time, because too many orthotitanate nuclei are formed in a short period of time, the distance between the nuclei is too close, which easily forms a semi-solid gel. The nucleus particles do not have time to grow, the nuclei become more and more clumped together, and the activity of the seed crystals is low. If titanium liquid A is added to the weakly alkaline compound for too long, the orthotitanate nuclei formed first will gradually grow larger over time. The orthotitanate nuclei formed later will be thinner than the orthotitanate nuclei formed first, resulting in uneven orthotitanate nuclei and uneven hydrolyzed metatitanate particles.

[0044] From slow to fast: before the rapid reaction of titanium liquid and weak alkaline compound, add slowly, and after the rapid reaction, add quickly. It takes two-thirds of the time before the rapid reaction and one-third of the time after the rapid reaction. The total time is within 20-60 seconds (conventional addition of alkali is 2-3 minutes), preferably 40-60 seconds.

[0045] The present invention also discloses a metatitanic acid particle prepared by the titanium liquid hydrolysis method. The metatitanic acid particle has an aspect ratio of 1.2-1.5 μm, a water washing time of 60-70 min, and an iron content of 23-28 ppm.

[0046] The invention also discloses titanium dioxide powder prepared by using the metatitanic acid particles. The quality indicators of the titanium dioxide powder are: L: 98.70-98.80, b: 1.46-1.56, and tinting power: 100%.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The present invention solves the problem of poor stability of orthotitanic acid nuclei prepared from titanium liquid with poor stability. The titanium liquid with poor stability is reacted with sodium metaaluminate to prepare orthotitanic acid nuclei with good activity and stability.

[0049] 2. After adding the orthotitanic acid nuclei prepared by the present invention to the titanium liquid with poor stability, regular crystals, uniform particle size, and extremely low impurity content of metatitanic acid particles can be obtained. The washing time is short, and the iron content of metatitanate after washing is low. The obtained titanium dioxide product has excellent whiteness, tinting power and other properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a photo of the initial stability of the orthotitanate crystal nuclei prepared in Examples 1 and 2 of the present invention;

[0051] Figure 2This is a photo of the final stability of the orthotitanate crystal nuclei prepared in Examples 1 and 2 of the present invention;

[0052] Figure 3 This is a photo of the initial stability of the orthotitanate crystal nucleus prepared in Comparative Example 1 of the present invention;

[0053] Figure 4 The diameter-to-pitch ratio in Example 1 of the present invention is 1.275;

[0054] Figure 5 The diameter-to-pitch ratio in Example 2 of the present invention is 1.407;

[0055] Figure 6 The diameter-to-pitch ratio in Comparative Example 1 of the present invention is 2.152;

[0056] Figure 7 The diameter-to-pitch ratio in Comparative Example 2 of the present invention is 1.248. DETAILED DESCRIPTION

[0057] Initial stability of the titanium solution: After adding the alkaline compound to the titanium solution, immediately take 10ml of seed crystals and test their stability. This is the initial stability. If the titanium solution has poor stability, the initial stability of the seed crystals prepared using conventional seed crystal preparation methods will be very low. See Comparative Example 1.

[0058] Example 1

[0059] The stability of titanium liquid A and titanium liquid B is 100ml.

[0060] (1) Weigh 300g of sodium metaaluminate with a concentration of 5% into a beaker, weigh 550g of titanium liquid A with a concentration of 24%, and pour titanium liquid A into the beaker containing sodium metaaluminate from slow to fast (total time 58 seconds), heat to 40°C, mature for 15 minutes, and cool to below 25°C with ice water to obtain orthotitanic acid crystal nuclei. Take 10ml of seed crystals to test its initial stability of 160ml, continue to mature until its final stability is 110ml, the data are shown in Table (1). Take 1ml of seed crystals to test its TiO2 concentration of 145g / L.

[0061] (2) Weigh 1000g of titanium liquid B with a concentration of 24% (198g / L in terms of TiO2) and place it in a four-necked flask. Weigh 38ml of orthotitanic acid nuclei obtained in the first step and add them to the four-necked flask. Stir for 10 minutes, heat to 102°C, and keep warm for 32 minutes until the hydrolyzed titanium liquid turns grayish white and the hydrolysis rate reaches 82.3%. Then heat the titanium liquid B to boiling and maintain this temperature for 120 minutes. The hydrolysis is completed to obtain metatitanic acid particles. Figure 4As shown, a small amount of metatitanic acid particles were taken and the particle size of the metatitanic acid was measured using a laser particle size analyzer. The diameter-to-pitch ratio was 1.275 μm. The specific data is shown in Table (2). The metatitanic acid particles were washed with water for only 60 minutes. The iron content of the metatitanic acid particles was only 23 ppm after bleaching, salt treatment, and calcination. The quality indicators of the final titanium dioxide product were: L: 98.73, b: 1.56, and tinting power: 100%. The data are shown in Table (2).

[0062] Example 2

[0063] The stability of titanium liquid A and titanium liquid B is 0ml.

[0064] (1) Weigh 4g of sodium metaaluminate with a concentration of 2% into a beaker, weigh 250g of titanium liquid A with a concentration of 24%, and pour titanium liquid A into the beaker containing sodium metaaluminate from slow to fast (total time 42 seconds), heat to 35°C, and mature for 5 minutes. Prepare orthotitanic acid nuclei by cooling to below 25°C with ice water. Take 10ml of seed crystals and test its initial stability, which is 165ml. Continue to mature until its final stability is 110ml. The data are shown in Table (1). Take 1ml of seed crystals and test its TiO2 concentration, which is 138g / L.

[0065] (2) Weigh 500g of titanium liquid B with a concentration of 24% (198g / L in terms of TiO2) and place it in a four-necked flask. Weigh 24.3ml of orthotitanic acid nuclei obtained in the first step and add them to the four-necked flask. Stir for 10 minutes, heat to 102°C, and keep warm for 35 minutes until the hydrolyzed titanium liquid turns grayish white and the hydrolysis rate reaches 81.1%. Then heat the titanium liquid B to boiling and maintain this temperature for 120 minutes. The hydrolysis is completed and metatitanic acid particles are obtained. Figure 5 As shown, a small amount of metatitanic acid particles were taken and the particle size of the metatitanic acid was measured using a laser particle size analyzer. The diameter-to-width ratio was 1.407 μm. The specific data is shown in Table (2). The metatitanic acid particles were washed with water, and the washing time was only 63 minutes. The iron content of the metatitanic acid particles was only 28 ppm after bleaching, salt treatment, and calcination. The quality indicators of the final titanium dioxide product were: L: 98.78b: 1.46 color reduction power: 100%. The data are shown in Table (2).

[0066] Comparative Example 1

[0067] The stability of titanium liquid A and titanium liquid B is 200 ml (titanium liquid with poor stability and conventional titanium liquid hydrolysis method are selected).

[0068] (1) Measure 50 ml of sodium hydroxide with a concentration of 100 g / L into a beaker. According to the preparation requirements of orthotitanic acid nuclei with a titanium-alkali ratio of 6.4:1, measure 162 ml of titanium liquid A with a TiO2 concentration of 198 g / L. Heat the titanium liquid A and sodium hydroxide to 80°C respectively. Pour the titanium liquid A into the alkali cup over 3 minutes to prepare orthotitanic acid nuclei. Take 10 ml of seed crystals and test its initial stability, which is 75 ml (very low stability). After the preparation is completed, test its final stability again, which is 50 ml. Take 1 ml of seed crystals and test its TiO2 concentration, which is 152 g / L.

[0069] (2) 500 ml of titanium liquid was weighed into a four-necked flask, and 13.7 ml of seed crystals were added. The amount of seed crystals was added according to the TiO2 weight ratio of 2.1%. Stir for 10 minutes and heat to boiling. When the hydrolyzed titanium liquid was found to be grayish white during boiling, the temperature was stopped for 30 minutes, and the temperature was raised again to a second boiling point. The temperature was kept for 3 hours, and the hydrolysis was completed. Figure 6 As shown, a small amount of the hydrolyzed material was taken and the particle size of the metatitanic acid was measured using a laser particle size analyzer. The diameter-to-pitch ratio was 2.152 μm. The specific data is shown in Table (2). The hydrolyzed material was washed with water for 85 minutes. The iron content of the metatitanic acid particles was as high as 87 ppm. The quality indicators of the final product after bleaching, salt treatment, and calcination were: L: 97.73b: 2.21, and tinting power: 80%.

[0070] Comparative Example 2

[0071] The stability of titanium liquid is 500ml (select titanium liquid with good stability and conventional titanium liquid hydrolysis method)

[0072] (1) Measure 50 ml of sodium hydroxide with a concentration of 100 g / L into a beaker. According to the requirements for preparing orthotitanic acid nuclei with a titanium-alkali ratio of 6.4:1, measure 162 ml of titanium liquid A with a TiO2 concentration of 198 g / L. Heat the titanium liquid A and the alkali to 80°C respectively. Pour the titanium liquid A into the alkali cup over 3 minutes to prepare orthotitanic acid nuclei. Take 10 ml of seed crystals and test its initial stability, which is 165 ml. Continue to heat to 95°C for aging. After 6 minutes, test the seed crystal stability and it is 110 ml. 1 ml of seed crystals test its TiO2 concentration to 162 g / L.

[0073] (2) 500 ml of titanium liquid was weighed into a four-necked flask, and 12.8 ml of hydrolysis seed crystals were added. The amount of seed crystals was added according to the TiO2 weight ratio of 2.1%. Stir for 10 minutes. After heating to boiling, the hydrolysis titanium liquid turned grayish white after 20 minutes. Stop heating for 30 minutes, heat it again to a second boiling, and keep it warm for 3 hours. The hydrolysis is complete. Figure 7As shown, a small amount of the hydrolyzed material was taken and the particle size of the metatitanic acid was measured using a laser particle size analyzer. The diameter-to-pitch ratio was 1.248 μm. The specific data is shown in Table (2). The hydrolyzed material was washed with water for 60 minutes. The iron content of the metatitanic acid particles was as high as 25 ppm. The quality indicators of the final product after bleaching, salt treatment, and calcination were: L: 98.75b: 1.48, and tinting power: 100%.

[0074] Table 1 Stability and activity of the metatitanic acid particles obtained in the examples and comparative examples

[0075]

[0076] Table 2 Quality indicators of the metatitanic acid particles obtained in the examples and comparative examples

[0077]

[0078] In Table 2, D10 represents the particle size at 10% of the cumulative distribution of particles, D50 represents the particle size at 50% of the cumulative distribution of particles, and D90 represents the particle size at 90% of the cumulative distribution of particles; the diameter-to-spacing ratio = (D90-D10) / D50, which represents the width of the particle size distribution. The smaller the diameter-to-spacing ratio value, the narrower the particle size distribution of the hydrolyzed slurry particles.

[0079] The washing time of the hydrolysis material has a great relationship with its particle size distribution. The particle size distribution of the hydrolysis slurry particles is uniform, the washing time is short, and the iron titanate content after washing is low.

[0080] The quality indicators of finished titanium dioxide are related to the particle size distribution and iron content of the hydrolyzed slurry particles. The particle size distribution of the hydrolyzed slurry particles is uniform, the iron titanate content after washing is low, the L value is high, and the b value is low.

[0081] The hydrolyzed particles in Examples 1, 2, and Comparative Example 2 exhibited uniform particle size distribution, short washing times, and low iron metatitanate content after washing, resulting in high-quality titanium dioxide products with high tinting power. The titanium dioxide produced using the less stable titanium dioxide solution in the present invention is of comparable quality to the titanium dioxide produced using the more stable titanium dioxide solution in Comparative Example 2. This present invention addresses the issue of using less stable titanium dioxide solutions to produce high-quality titanium dioxide products.

[0082] In Comparative Example 1, the hydrolyzed material particles were too coarse, the water flow rate was extremely high, and the washing process was essentially air washing. The hydrolyzed slurry had an uneven particle size distribution, making it difficult to remove impurity ions. This resulted in long washing times and a high iron metatitanate content after washing. The resulting titanium dioxide product had a low L value and low tinting power.

Claims

1. A method for hydrolyzing titanium liquid, characterized in that: The following steps are involved: S1. Add orthotitanate nuclei to titanium liquid B, stir, heat and hydrolyze, and keep warm; S2. When the hydrolysis rate of titanium liquid B reaches 70-90%, continue to heat it to boiling and keep it warm to obtain metatitanate particles; The mass concentration of the titanium liquid B is 22-28%, and the stability K of the titanium liquid B is less than 500 ml; Stability of titanium liquid K = volume of distilled water used for titanium liquid hydrolysis / volume of titanium liquid; The initial stability of the orthotitanic acid crystal nucleus is 160-170 ml, and the final stability of the orthotitanic acid crystal nucleus is 110 ml.

2. The method for hydrolyzing titanium liquid according to claim 1, characterized in that: The mass percentage of TiO2 in the orthotitanate crystal nuclei in S1 to the titanium liquid B is 0.5-0.7%.

3. The method for hydrolyzing titanium liquid according to claim 1, characterized in that: The stirring time in S1 is 8-15 minutes.

4. The method for hydrolyzing titanium liquid according to claim 1, characterized in that: The stirring time in S1 is 8-10 minutes.

5. The method for hydrolyzing titanium liquid according to claim 1, characterized in that: The temperature of the hydrolysis in S1 is 90-103°C; The holding time in S1 is 20-40 minutes; The boiling time in S2 is 120-150 minutes.

6. The titanium liquid hydrolysis method according to claim 1, characterized in that: The method for preparing the orthotitanate crystal nucleus comprises the following steps: Titanium liquid A is added to a weakly alkaline compound and mixed evenly, and then heated, aged, and rapidly cooled to obtain orthotitanate crystal nuclei. The stability K of the titanium liquid A is less than 500 mL.

7. The titanium liquid hydrolysis method according to claim 6, characterized in that: The mass concentration of the titanium liquid A is 22-28%.

8. The titanium liquid hydrolysis method according to claim 6, characterized in that: The mass concentration of the titanium liquid A is 24-26%.

9. The method for hydrolyzing titanium liquid according to claim 6, characterized in that: The weakly alkaline compound in S1 is sodium metaaluminate, and the mass concentration is 1-8%.

10. The method for hydrolyzing titanium liquid according to claim 9, characterized in that: The mass concentration of the sodium metaaluminate is 3-5%.

11. The method for hydrolyzing titanium liquid according to claim 6, characterized in that: The weight ratio of the titanium liquid A to the weakly alkaline compound in S1 is (250-550): (4-300); The temperature in S1 is raised to 35-45°C, and the curing time in S1 is 5-15 minutes; In the method for preparing orthotitanate crystal nuclei, the temperature after cooling is below 25°C; The addition time of the titanium liquid A is 20-60s, and the addition speed of the titanium liquid A is from slow to fast.

12. The method for hydrolyzing titanium liquid according to claim 6, characterized in that: The addition time of the titanium liquid A is 40-60s.

Images