Method for preparing metatitanic acid with stable particle size rapidly before concentration of titanium liquid in titanium dioxide production

Abstract

The application discloses a method for preparing metatitanic acid with stable particle size from concentrated titanium liquid in titanium dioxide production, and particularly relates to the technical field of titanium dioxide production. First, the concentrated titanium liquid and alkali liquid are respectively preheated to 85-95 DEG C, the concentrated titanium liquid is added into the alkali liquid, the temperature is maintained at 95-120 DEG C for reaction, the reaction time is 5-10 min, and the crystal seed is obtained when the detection of crystal seed stability reaches below 100 ml water / 10 ml titanium liquid; then the crystal seed obtained in step one is added into the concentrated titanium liquid, and the stirring, pressurizing and heating are carried out for reaction, the reaction time is 15-60 min, and the reaction is kept for maturation after the reaction is completed; finally, the titanium liquid after the reaction in step two is cooled, and metatitanic acid with stable particle size is obtained after filtration.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide production technology, specifically to a method for rapidly preparing stable-particle-size metatitanic acid from titanium liquid before concentration in titanium dioxide production. Background Technology

[0002] The sulfuric acid process for titanium dioxide production, a mainstream technology in China, has a critical hydrolysis step that has garnered significant attention. The production of metatitanic acid during hydrolysis often leads to product quality fluctuations due to the lengthy process and difficulty in controlling key processes. Inconsistent particle size makes subsequent washing steps challenging, further exacerbating quality fluctuations. Furthermore, the irreversible nature of hydrolysis makes the recovery of substandard products difficult. Currently, to control hydrolysis fluctuations and mitigate the difficulties in washing away impurities in the sulfuric acid process for titanium dioxide production, the method used is to first concentrate the low-concentration titanium solution before it enters the hydrolysis stage.

[0003] Concentration involves using vacuum concentration to increase the titanium content in the purified titanium solution after acid hydrolysis and crystallization, while reducing some impurities. This allows for control of the reaction rate during the hydrolysis step and facilitates control of the metatitanic acid particle size. However, this method not only increases the economic and time costs of production, but also places extremely high demands on the stability of the titanium solution before the hydrolysis stage. If the temperature control in the concentration stage is not good, hydrolysis can easily occur prematurely, resulting in a deterioration in the quality of the metatitanic acid product from the hydrolysis stage, requiring downgrading or scrapping the entire batch of titanium solution.

[0004] Hydrolysis involves first preparing a portion of the molten titanium as seed crystals, then adding these seed crystals to the molten titanium to be hydrolyzed and mixing them. The temperature is then increased to initiate the hydrolysis reaction, transforming the tetravalent titanium in the molten titanium into a white solid, metatitanic acid. Hydrolysis can be classified according to the seed crystal preparation method into externally seeded hydrolysis and self-generated seeded hydrolysis, and according to the operating pressure into atmospheric pressure hydrolysis, low-pressure hydrolysis, and pressurized hydrolysis.

[0005] In the domestic sulfuric acid process for producing pigment-grade titanium dioxide, there are three existing hydrolysis processes: hydrolysis with added seed crystals at atmospheric pressure, hydrolysis with added seed crystals at low pressure, and hydrolysis with self-generated seed crystals at atmospheric pressure.

[0006] Adding seed crystals for hydrolysis at atmospheric pressure, such as Chinese patent CN106430300A, is a method for adding seed crystals for alkali neutralization in the production of titanium dioxide by the sulfuric acid process. This patent mentions that the concentration of titanium liquid is 195-205 g / L, and the titanium liquid that needs to be concentrated in advance is used for subsequent reactions. In the examples of this patent, it can be seen that this patent belongs to the method of adding seed crystals, and the overall reaction time is often no less than 4 hours, which is a long reaction time.

[0007] Chinese patent CN106241866A discloses a method for preparing titanium dioxide using high-concentration external seed crystals. As can be seen from the embodiments of this patent, it also involves external seed crystals, and the reaction time is no less than 4 hours, indicating a long reaction time.

[0008] The self-generated seed crystal hydrolysis process at atmospheric pressure, such as Chinese patent CN109205663A, describes a method for preparing self-generated seed crystals in titanium dioxide production. This involves rapidly diluting a portion of the titanium solution with bottom water to prepare seed crystals, then adding more titanium solution to dilute the concentration to a certain range before atmospheric pressure hydrolysis. However, before dilution, the titanium solution in this patent is still of a relatively high concentration. After adding bottom water, the total titanium concentration is controlled at 155-175 g / L. Furthermore, as mentioned in this patent, the total feeding time for adding the initial titanium solution to the bottom water is controlled to be 15-20 minutes. This is similar to application number CN 101607737. The feeding time described in Patent A is basically the same, but the key difference between the former invention and the latter patent lies in the fact that it needs to be controlled during the process of adding the initial titanium liquid to the bottom water. When the amount of titanium liquid added is 3.0% to 3.5% of the total volume of titanium liquid, the total sulfuric acid concentration of the reaction system is 0.6 ± 0.02 mol / L. In other words, the other preparation time of this patent is basically the same as that of Chinese Patent CN101607737 A, and the reaction time is also basically the same. After conversion, its reaction time should not be less than 5 hours, which is a relatively long reaction time. Summary of the Invention

[0009] Therefore, this invention provides a method for rapidly preparing stable metatitanic acid from titanium liquid before concentration in titanium dioxide production, in order to solve the problems in the prior art.

[0010] This invention optimizes the parameters of the hydrolysis process and uses pre-concentrated titanium liquid as the hydrolysis raw material, which greatly shortens the reaction time while stably generating metatitanic acid with a narrow and uniform particle size distribution that can be used in the production of pigment-grade titanium dioxide.

[0011] This invention directly uses the titanium liquid before concentration after crystallization separation into the hydrolysis stage. By combining the titanium liquid before concentration after crystallization separation with a pressurized method for hydrolysis, metatitanic acid that meets the requirements for pigment-grade titanium dioxide production can be prepared without the concentration step. In other words, the concentration stage is omitted, achieving cost savings in terms of low energy consumption and time.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] According to the present invention, a method for rapidly preparing particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production is provided, the method comprising:

[0014] Step 1: Preparation of seed crystals

[0015] The titanium solution and the alkaline solution are preheated to 85℃~95℃ respectively. Titanium solution is added to the alkaline solution, and the temperature is maintained at 95℃~120℃ for reaction. The reaction time is 10min~30min. When the stability of the seed crystal reaches below 100ml water / 10ml titanium solution, the seed crystal is obtained.

[0016] Step 2, Seed-induced reaction

[0017] Add the seed crystals obtained in step one to the titanium liquid before concentration, stir, pressurize and heat to carry out the reaction, the reaction time is 15-60 min, and after the reaction is completed, keep warm and mature.

[0018] Step 3, Post-processing

[0019] After the reaction in step two is completed, the titanium liquid is cooled and filtered to obtain metatitanic acid with stable particle size.

[0020] Furthermore, in step one, the alkaline solution is one or more of ammonia, sodium hydroxide, potassium hydroxide, and lithium hydroxide, and the concentration of the alkaline solution is 100g / L to 200g / L.

[0021] Furthermore, in step one, the titanium liquid before concentration is an acidic solution, and the total titanium content of the titanium liquid, calculated as TiO2, is between 130 g / L and 165 g / L.

[0022] Furthermore, in step one, the ratio of titanium solution to alkali solution is 4:1 to 1.5:1.

[0023] In step two, the conditions for the stirring, pressurizing, and heating reaction are as follows: stirring speed of 300-550 RPM, final temperature of 120-135℃, and pressure of 0.2-0.3 MPa. Heating provides the necessary energy for the reaction: the formation of metatitanic acid is an endothermic reaction, and heating provides more energy, intensifying the thermal motion of reactant molecules and increasing their kinetic energy. When the temperature rises to 120-135℃, molecular motion becomes more intense, and the frequency and energy of collisions between reactant molecules increase significantly, making it easier to overcome the activation energy required for the reaction, thereby accelerating the reaction rate and allowing the reaction to reach its endpoint in a shorter time. Increased temperature may alter the reaction pathway, making the reaction more likely to proceed towards the formation of metatitanic acid. Under high-temperature conditions, the number of activated molecules increases, the number of effective collisions increases, which is more conducive to the formation of metatitanic acid crystal nuclei, and the nucleus formation rate is accelerated, thus shortening the reaction time.

[0024] Appropriate pressure can increase the concentration of gaseous substances in a reaction system. In the preparation reaction of metatitanic acid, pressure reduces the distance between reactant molecules, increasing the number of molecules per unit volume, which is equivalent to increasing the concentration of reactants and thus accelerating the reaction rate. According to Le Chatelier's principle, appropriate pressure shifts the chemical reaction towards the direction of decreasing volume. In the preparation reaction of metatitanic acid, if the sum of the stoichiometric coefficients of the gases in the reactants is greater than the sum of the stoichiometric coefficients of the gases in the products, then pressure will shift the reaction in the forward direction, favoring the formation of metatitanic acid, promoting the reaction to proceed more quickly to the endpoint, and reducing the time required to reach equilibrium.

[0025] Increasing temperature increases molecular kinetic energy, while increasing pressure reduces intermolecular distance. Under the combined effect of these two factors, the frequency and energy of collisions between reactant molecules significantly increase, making it easier to reach the activation energy required for the reaction and thus greatly accelerating the reaction rate. Increasing temperature and pressure can place the reaction system in a state more favorable for the reaction to proceed, thereby shortening the reaction time.

[0026] Stirring, pressurization, and heating work together to create a more stable, uniform environment conducive to the reaction. Stirring ensures uniform mixing of the reactants and provides energy, heating accelerates molecular motion and the reaction process, and pressurization increases the reaction rate and inhibits excessive particle growth. Through the synergistic effect of these three factors, various parameters within the reaction system, such as concentration, temperature, and pressure, are maintained at optimal levels, which is beneficial for the uniform nucleation and growth of metatitanic acid particles.

[0027] Under stirred, pressurized, and heated conditions, the reactants can be uniformly distributed and reacted throughout the entire reaction system, ensuring that each particle has similar growth conditions and opportunities. This prevents some particles from growing too fast and others too slow due to differences in local reaction conditions, thus ensuring a more uniform particle size distribution of the metatitanic acid particles.

[0028] Furthermore, in step two, the Fe in the titanium solution before concentration... 2+ The concentration is 50 g / L to 66 g / L.

[0029] Furthermore, in step two, the ratio of the titanium liquid before concentration to the seed crystal is 2% to 8%.

[0030] Furthermore, in step two, the curing time is 15-75 minutes.

[0031] Furthermore, in step three, the cooling time is 20 to 30 minutes.

[0032] The hydrolysis rate is inversely proportional to the total titanium content in the titanium solution.

[0033] TiOSO4+3H2O→Ti(OH)4↓+H2SO4;

[0034] TiOSO4+2H20→H2TiO3↓+H2SO4;

[0035] In the titanium dioxide production process, the higher the total titanium concentration in the titanium liquid, the higher the sulfuric acid concentration is often. Therefore, the titanium liquid with a higher total titanium content is more stable and requires stronger reaction conditions to proceed. Thus, within a certain range, the titanium liquid can be diluted to promote the hydrolysis reaction, that is, the hydrolysis rate is inversely proportional to the total titanium content of the titanium liquid.

[0036] The present invention has the following advantages:

[0037] Compared to existing methods for preparing metatitanic acid that require concentrated titanium solution, this invention eliminates the need for concentration. Before concentration, a titanium ion content (based on TiO2) of 130 g / L to 159 g / L in the titanium solution is sufficient to meet the preparation requirements. Although the addition of alkali further reduces the titanium ion content (based on TiO2) in the titanium solution using this method, it still meets the preparation requirements.

[0038] The method of this invention directly omits the concentration step, and with the shortened hydrolysis time, the overall process of the sulfuric acid process for titanium dioxide is shortened, further increasing the yield per unit time. It utilizes the inverse relationship between the hydrolysis rate and the total titanium content in the titanium solution; directly using the titanium solution before concentration, combined with stirring, pressurization, and heating (pressurization promotes the forward hydrolysis reaction and improves titanium utilization), greatly shortens the reaction time, reduces energy consumption and cost, and achieves rapid preparation. While significantly shortening the reaction time, it can stably generate metatitanic acid with a narrow and uniform particle size distribution, which can be used as a substitute for metatitanic acid in existing pigment-grade sulfuric acid hydrolysis processes. Attached Figure Description

[0039] 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.

[0040] 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.

[0041] Figure 1 This is a SEM image of metatitanic acid provided in Example 1 of the present invention;

[0042] Figure 2 This is a SEM image of metatitanic acid provided in Comparative Example 2 of the present invention. Detailed Implementation

[0043] 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.

[0044] Example 1

[0045] This embodiment provides a method for rapidly preparing particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production:

[0046] (1) Take the titanium liquid before concentration and the alkaline solution for preheating. The titanium ion content of the titanium liquid before concentration is 158 g / L (calculated as TiO2), the concentration of the alkaline solution is 150 g / L, the preheating temperature of the titanium liquid before concentration is 85℃, and the preheating temperature of the alkaline solution is 85℃.

[0047] (2) Take 200 mL of the preheated titanium solution before concentration and add it to 100 mL of the preheated alkaline solution. Stir and heat to 98°C, maintain the temperature for 8 min, and test the stability at 65 mL water / 10 mL titanium solution.

[0048] (3) Take 338 mL of the titanium liquid before concentration and place it in a pressure-resistant reactor to preheat to 65°C. Add 22 mL of the seed crystals prepared in (2) to the titanium liquid.

[0049] (4) Pass compressed air into the pressure-resistant reactor to make the pressure reach 0.2MPa, set the stirring speed to 500RPM, start timing when heating to 90℃, continue to rise the temperature to 120℃ as the hydrolysis temperature, react for 45min, and keep warm for 30min.

[0050] (5) Cool the titanium liquid after the reaction is complete for 22 minutes and the temperature of the titanium liquid is measured to be 60.8℃.

[0051] (6) After cooling, the mixture was filtered and the particle size D of the metatitanic acid was measured. 10 It is 1.391 μm, D 50 It is 2.556 μm, D 90 It is 4.257 μm, D [4,3] D is 2.694. [3,2] The diameter is 2.200 μm, the uniformity is 0.341, and the radial distance is 1.121.

[0052] SEM image as follows Figure 1 As shown.

[0053] Total reaction time: 80 min; hydrolysis rate: 97.24%.

[0054] Example 2

[0055] This embodiment provides a method for rapidly preparing particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production:

[0056] (1) Take the titanium liquid before concentration and the alkaline solution for preheating. The titanium ion content of the titanium liquid before concentration is 130 g / L (calculated as TiO2), the concentration of the alkaline solution is 125 g / L, the preheating temperature of the titanium liquid before concentration is 90℃, and the preheating temperature of the alkaline solution is 90℃.

[0057] (2) Take 200 mL of the preheated titanium solution before concentration and add it to 100 mL of the preheated alkaline solution. Stir and heat to 98°C, maintain the temperature for 8 min, and test the stability of 74 mL water / 10 mL titanium solution.

[0058] (3) Take 338 mL of the titanium liquid before concentration and place it in a pressure-resistant reactor to preheat to 65°C. Add 22 mL of the seed crystals prepared in (2) to the titanium liquid.

[0059] (4) Pass compressed air into the pressure-resistant reactor to make the pressure reach 0.2MPa, set the stirring speed to 500RPM, start timing when heating to 90℃, continue to rise the temperature to 130℃ as the hydrolysis temperature, react for 45min, and keep warm for 30min.

[0060] (5) Cool the titanium liquid after the reaction is complete for 22 minutes and the temperature of the titanium liquid is measured to be 61.4℃.

[0061] (6) After cooling, the mixture was filtered and the particle size D of the metatitanic acid was measured. 10 The value is 1.350 μm, and the D50 is 2.541 μm. 90 It is 4.298 μm, D [4，3] It is 2.690 μm, D [3,2] The consistency is 2.169, the diameter is 0.354, and the radial distance is 1.160.

[0062] Total reaction time: 78 min; hydrolysis rate: 97.14%.

[0063] Example 3

[0064] This embodiment provides a method for rapidly preparing particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production:

[0065] (1) Take the titanium liquid before concentration and the alkaline solution for preheating. The titanium ion content of the titanium liquid before concentration is 140 g / L (calculated as TiO2), the concentration of the alkaline solution is 100 g / L, the preheating temperature of the titanium liquid before concentration is 95℃, and the preheating temperature of the alkaline solution is 95℃.

[0066] (2) Take 200 mL of the preheated titanium solution before concentration and add it to 100 mL of the preheated alkaline solution. Stir and heat to 98°C, maintain the temperature for 8 min, and test the stability of 82 mL water / 10 mL titanium solution.

[0067] (3) Take 338 mL of the titanium liquid before concentration and place it in a pressure-resistant reactor to preheat to 65°C. Add 22 mL of the seed crystals prepared in (2) to the titanium liquid.

[0068] (4) Pass compressed air into the pressure-resistant reactor to make the pressure reach 0.2MPa, set the stirring speed to 500RPM, start timing when heating to 90℃, continue to rise the temperature to 135℃ as the hydrolysis temperature, react for 45min, and keep warm for 30min.

[0069] (5) Cool the titanium liquid after the reaction is complete for 22 minutes and the temperature of the titanium liquid is measured to be 60.8℃.

[0070] (6) After cooling, the mixture was filtered and the particle size D of the metatitanic acid was measured. 10 It is 1.376 μm, D 50 It is 2.560μm, D 90 It is 4.274 μm, D [4，3] It is 2.697 μm, D [3,2] The consistency is 2.195, the diameter is 0.344, and the radial distance is 1.132.

[0071] Total reaction time: 80 min; hydrolysis rate: 97.37%.

[0072] Example 4

[0073] This embodiment provides a method for rapidly preparing particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production:

[0074] (1) Take the titanium liquid before concentration and the alkaline solution for preheating. The titanium ion content of the titanium liquid before concentration is 158 g / L, the concentration of the alkaline solution is 125 g / L, the preheating temperature of the titanium liquid before concentration is 85℃, and the preheating temperature of the alkaline solution is 85℃.

[0075] (2) Take 200 mL of the preheated titanium solution before concentration and add it to 100 mL of the preheated alkaline solution. Stir and heat to 98°C, maintain the temperature for 8 min, and test the stability of 72 mL water / 10 mL titanium solution.

[0076] (3) Take 338 mL of the titanium liquid before concentration and place it in a pressure-resistant reactor to preheat to 65°C. Add 22 mL of the seed crystals prepared in (2) to the titanium liquid.

[0077] (4) Pass compressed air into the pressure-resistant reactor to make the pressure reach 0.2MPa, set the stirring speed to 500RPM, start timing when heating to 90℃, continue to rise the temperature to 135℃ as the hydrolysis temperature, react for 45min, and keep warm for 30min.

[0078] (5) Cool the titanium liquid after the reaction is complete for 22 minutes and the temperature of the titanium liquid is measured to be 62.0℃;

[0079] (6) After cooling, the mixture was filtered and the particle size D of the metatitanic acid was measured. 10 It is 1.396 μm, D 50 It is 2.590 μm, D 90 It is 4.335 μm, D [4，3] It is 2.733 μm, D [3,2] The consistency is 2.220, the diameter is 0.345, and the radial distance is 1.135.

[0080] Total reaction time: 80 min; hydrolysis rate: 97.23%.

[0081] Example 5

[0082] This embodiment provides a method for rapidly preparing particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production:

[0083] (1) Take the titanium liquid before concentration and the alkaline solution for preheating. The titanium ion content of the titanium liquid before concentration is 158 g / L, the concentration of the alkaline solution is 125 g / L, the preheating temperature of the titanium liquid before concentration is 85℃, and the preheating temperature of the alkaline solution is 85℃.

[0084] (2) Take 200 mL of the preheated titanium solution before concentration and add it to 100 mL of the preheated alkaline solution. Stir and heat to 98°C, maintain the temperature for 8 min, and test the stability of 69 mL water / 10 mL titanium solution.

[0085] (3) Take 338 mL of the titanium liquid before concentration and place it in a pressure-resistant reactor to preheat to 65°C. Add 22 mL of the seed crystals prepared in (2) to the titanium liquid.

[0086] (4) Pass compressed air into the pressure-resistant reactor to make the pressure reach 0.2MPa, set the stirring speed to 500RPM, start timing when heating to 90℃, continue to rise the temperature to 130℃ as the hydrolysis temperature, react for 45min, and keep warm for 30min.

[0087] (5) Cool the titanium liquid after the reaction is complete for 22 minutes. The temperature of the titanium liquid is measured to be 63.7℃.

[0088] (6) After cooling, the mixture was filtered and the particle size D of the metatitanic acid was measured. 10 It is 1.404 μm, D 50It is 2.558 μm, D 90 It is 4.244 μm, D [4，3] It is 2.694 μm, D [3,2] The consistency is 2.206, the diameter is 0.338, and the radial distance is 1.110.

[0089] Total reaction time: 80 min; hydrolysis rate: 97.55%.

[0090] Comparative Example 1

[0091] This comparative example provides a method for the rapid preparation of particle size-stable metatitanic acid from titanium liquid before concentration in titanium dioxide production:

[0092] a. Calculate the required bottom water volume: The specifications of the titanium hydrolysis solution are: total titanium concentration (TiO2 mass basis) 185.6 g / L, F value 1.89. The total titanium concentration of the hydrolysis system in this experiment is controlled at 160 g / L, and the required bottom water volume is calculated.

[0093] b. Calculate the amount of sulfuric acid or sodium hydroxide to be added: Based on the fact that when 3.5% of the total titanium liquid volume is added, the corresponding sulfuric acid concentration of the system is 0.62 mol / L, weigh out 0.35 kg / (cubic meter titanium liquid) of sodium hydroxide, dissolve it in water and dilute it to the corresponding calculated bottom water volume, and mix well to obtain the bottom water.

[0094] C. Preheat the hydrolyzed titanium solution and the base water to 98℃ respectively. Then, add the preheated hydrolyzed titanium solution to the preheated base water at a uniform rate over 17 minutes, maintaining the hydrolysis system temperature at 98℃ during the addition process. After the addition is complete, heat the hydrolysis system to boiling (approximately 104℃), maintaining a heating rate of 1.20℃ / min for 5 minutes, keeping the system in a gentle boiling state. Stop heating and stirring when the solution turns gray (i.e., the graying point), and allow it to mature for 30 minutes. After maturation, heat the system to boiling again (approximately 105℃) while stirring, maintaining a heating rate of 2.0℃ / min for 13 minutes, keeping the system in a gentle boiling state. After the second heating to boiling for 90 minutes, add 10 ml of preheated deionized water (preheated to 90℃) to the system at a uniform rate to dilute the titanium solution concentration and promote the continued hydrolysis reaction. Hydrolysis is completed after 2.5 hours.

[0095] The particle size D of metatitanic acid was obtained 10 It is 1.891 μm, D 50 It is 3.346 μm, D 90 It is 5.472 μm, D [4,3] It is 3.505 μm, D [3，2] The diameter is 2.809 μm, the uniformity is 0.330, and the radial distance is 1.070.

[0096] Total reaction time: 305 min; hydrolysis rate: 96.12%.

[0097] Comparative Example 2

[0098] This comparative example provides a method for rapidly preparing metatitanic acid with stable particle size from titanium liquid before concentration in titanium dioxide production: the total amount of alkali added is such that the mass concentration of the alkali used is 10.5% to 12.5%, and other aspects are completely consistent with Example 1, resulting in metatitanic acid with a particle size D. 10 It is 2.367 μm, D 50 It is 3.937 μm, D 90 It is 6.295μm, D [4,3] It is 4.133 μm, D [3，2] The diameter is 3.308 μm, the uniformity is 0.313, and the radial distance is 0.998.

[0099] Total reaction time: 80 min; hydrolysis rate: 97.29%. Higher alkali concentrations tend to cause seed crystal deactivation and larger metatitanic acid particle size.

[0100] Comparative Example 3

[0101] This comparative example provides a method for rapidly preparing metatitanic acid with stable particle size from titanium liquid before concentration in titanium dioxide production: the hydrolysis temperature is 115℃, and all other steps are exactly the same as in Example 1, resulting in metatitanic acid with a particle size D. 10 It is 0.320μm, D 50 It is 2.679 μm, D 90 It is 6.351 μm, D [4,3] It is 2.808 μm, D [3,2] The diameter is 0.777 μm, the uniformity is 0.815, and the radial distance is 2.251.

[0102] Total reaction time: 80 min; hydrolysis rate: 87.69%. Lower temperatures will reduce the hydrolysis rate, and the resulting metatitanic acid particles will have inconsistent sizes, a wide range, and be sticky.

[0103] Comparative Example 4

[0104] This comparative example provides a method for rapidly preparing metatitanic acid with stable particle size from titanium liquid before concentration in titanium dioxide production: the hydrolysis temperature is 140℃, and all other steps are exactly the same as in Example 1, resulting in metatitanic acid with a particle size D. 10 It is 1.450 μm, D 50 It is 2.616 μm, D 90 It is 4.307 μm, D [4,3] It is 2.746 μm, D [3,2] The diameter is 4.307 μm, the uniformity is 0.335, and the radial distance is 1.092.

[0105] Total reaction time: 75 min; hydrolysis rate: 98.07%. Increasing the temperature will lead to an excessively rapid hydrolysis rate, resulting in inconsistent particle size of metatitanic acid. Continuously increasing the temperature will also increase production costs, making the economic benefits not low.

[0106] Comparative Example 5

[0107] This comparative example provides a method for rapidly preparing metatitanic acid with stable particle size from titanium liquid before concentration in titanium dioxide production: the hydrolysis pressure is 0.05 MPa, and all other parameters are exactly the same as in Example 1, yielding metatitanic acid with a particle size D. 10 It is 0.320μm, D 50 It is 2.679 μm, D 90 It is 6.351 μm, D [4,3] It is 2.808 μm, D [3,2] The diameter is 0.777 μm, the uniformity is 0.815, and the radial distance is 2.251.

[0108] Total reaction time: 80 min; hydrolysis rate: 92.47%. Pressure reduced by 0.15 MPa.

[0109] Comparative Example 6

[0110] This comparative example provides a method for rapidly preparing metatitanic acid with stable particle size from titanium liquid before concentration in titanium dioxide production: the hydrolysis pressure is 0.35 MPa, and all other parameters are exactly the same as in Example 1, yielding metatitanic acid with a particle size D. 10 It is 1.450 μm, D 50 It is 2.616 μm, D 90 It is 4.307 μm, D [4,3] It is 2.746 μm, D [3,2] The diameter is 4.307 μm, the uniformity is 0.335, and the radial distance is 1.092.

[0111] Total reaction time: 80 min; hydrolysis rate: 98.08%. Excessive pressure increase: 0.25 MPa.

[0112] Experimental Example 1

[0113] Examples 1-5 and Comparative Examples 1-6 were calcined using the same method, and the properties of the calcined samples are shown in Table 1.

[0114] Table 1

[0115]

[0116] As shown in Table 1, in terms of the two important pigment performance characteristics of tinting strength and hiding power, the product prepared by this invention is at the same level as the traditional concentrated product, and can be used as a low-cost alternative to the traditional hydrolysis technology.

[0117] 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 rapidly preparing stable metatitanic acid with a specific particle size from concentrated titanium liquid in the production of titanium dioxide, characterized in that, The method comprises: Step one, preparation of crystal seeds respectively, the concentrated pre-titanium liquid with a concentration of 130-158 g / L and alkali solution are preheated to 85-95 ℃, 200 mL of the preheated concentrated pre-titanium liquid is added into 100 mL of the preheated alkali solution, and the reaction is carried out at a temperature of 95-120 ℃, and the reaction time is 5-10 min, and the reaction is stopped when the detection of the stability of the crystal seeds reaches 65-82 mL of water per 10 mL of titanium liquid, and the crystal seed solution is obtained; wherein the concentration of the alkali solution is 100-200 g / L; Step two, crystal seed induction reaction After 338 mL of the concentrated pre-titanium liquid is preheated to 65 ℃, 22 mL of the crystal seed solution prepared in step one is added, and the reaction is carried out by stirring, pressurizing and heating, and the reaction time is 15-60 min, and after the reaction is completed, the maturation is carried out by keeping warm; The stirring, pressurizing and heating reaction conditions are as follows: the stirring speed is 300-550 RPM, the final heating temperature is 120-135 ℃, and the pressurizing pressure is 0.2-0.3 MPa; Step three, post-treatment After the titanium liquid in step two is reacted, it is cooled and filtered to obtain metatitanic acid with stable particle size.

2. The method for rapidly preparing stable metatitanic acid with a certain particle size from concentrated titanium liquid in the production of titanium dioxide according to claim 1, characterized in that, In step one, the alkali in the alkali solution is one or more of ammonia, sodium hydroxide, potassium hydroxide and lithium hydroxide.

3. The method for preparing stable metatitanic acid with a stable particle size rapidly from concentrated titanium liquid in the production of titanium dioxide according to claim 1, characterized in that, In step two, Fe in the titanium solution before concentration 2+ The concentration is 50 g / L to 66 g / L.

4. The method for preparing stable metatitanic acid with a stable particle size rapidly from concentrated titanium liquid in the production of titanium dioxide according to claim 1, characterized in that, In step two, the maturation time is 15-75 min.

5. The method for preparing stable metatitanic acid with a stable particle size rapidly from concentrated titanium liquid in the production of titanium dioxide according to claim 1, characterized in that, In step three, the cooling time is 20-30 min.

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