Preparation method of plastic special titanium dioxide primary product and plastic special titanium dioxide primary product

Abstract

The present disclosure relates to the technical field of titanium dioxide production, and particularly relates to a preparation method of plastic special titanium dioxide crude product and the plastic special titanium dioxide crude product, the preparation method comprises the following steps: step 1, mixing desalted water and metatitanic acid, stirring uniformly to obtain a first slurry; step 2, adding potassium hydroxide solution into the first slurry, stirring uniformly to obtain a second slurry; step 3, adding phosphoric acid solution into the second slurry, stirring uniformly to obtain a third slurry; step 4, adding aluminum sulfate solution into the third slurry, stirring uniformly to obtain a fourth slurry; step 5, adding ammonium salt solution into the fourth slurry, stirring uniformly to obtain a fifth slurry; step 6, filtering the fifth slurry to obtain a filter cake; step 7, calcining the filter cake to obtain the titanium dioxide crude product. The titanium dioxide crude product prepared by the preparation method has small and uniform particle size, low b value, high SCX value and blue bias, and meets the use requirements of the plastic industry.

Description

Technical Field

[0001] This disclosure relates to the technical field of titanium dioxide production, and in particular to a method for preparing a primary titanium dioxide product for plastics and the primary titanium dioxide product for plastics. Background Technology

[0002] Titanium dioxide (TiO2) is currently the world's best white pigment, widely used in coatings, plastics, inks, papermaking, synthetic fibers, cosmetics, food, and rubber industries. The plastics industry is the second largest user of titanium dioxide, experiencing rapid growth in recent years, with approximately 25% of titanium dioxide production used in this sector. As the best white inorganic pigment, titanium dioxide, when applied to plastics, not only provides whiteness, gloss, and hiding power, but also improves the lightfastness, heat resistance, and weather resistance of plastic products, enhances their physicochemical properties, and extends their service life. In short, the quality of titanium dioxide is crucial to the performance of the plastic products it colors.

[0003] Theoretically, the relative scattering ability of rutile titanium dioxide for blue, green, and red light is a function of the particle size. At 200 nm, the sum of scattering across all wavelengths reaches its maximum. When the particle size increases to between 250 and 300 nm, the scattering of blue light decreases rapidly, while the scattering of green and red light remains relatively unchanged. At 150 nm, blue light scattering reaches its maximum, while the scattering of light in the red and green ranges of the spectrum decreases significantly. The visible spectrum ranges from 380 to 780 nm, so the optimal particle size for ideal titanium dioxide should be controlled between 190 and 390 nm. However, human vision generally perceives bluish-white as whiter than pure white, and synthetic resins and plastics often exhibit strong absorption of short-wavelength white light for various reasons, causing the material to appear slightly yellowish. Smaller-particle-size titanium dioxide reflects more blue and green light than larger-particle-size titanium dioxide, resulting in a blue undertone and effectively masking yellowish or easily yellowed resins. Therefore, the particle size of titanium dioxide for plastics should be controlled to be small and uniform, with a low b value (yellow-blue hue value), a high SCX value (hue value), and a bluish hue. The key to determining the particle size and distribution of titanium dioxide is the preparation technology of the initial titanium dioxide product.

[0004] In existing technologies, the preparation of primary titanium dioxide products often employs single or simple composite modification processes, which make it difficult to simultaneously meet the core requirements of small particle size, low b-value, and bluish phase. Furthermore, the process parameters are not precise enough, resulting in poor adaptability of the prepared primary titanium dioxide products, which cannot meet the usage requirements of the plastics industry.

[0005] Based on the above, the existing technology needs further improvement. Summary of the Invention

[0006] To address the aforementioned technical problems, this disclosure provides a method for preparing a primary titanium dioxide product for plastics, comprising the following steps: Step 1: Mix the deionized water and metatitanic acid, stir well to obtain the first slurry; Step 2: Add potassium hydroxide solution to the first slurry and stir well to obtain the second slurry; Step 3: Add phosphoric acid solution to the second slurry and stir well to obtain the third slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir well to obtain the fourth slurry; Step 5: Add ammonium salt solution to the fourth slurry, stir well, and obtain the fifth slurry; Step 6: Filter the fifth slurry to obtain a filter cake; Step 7: Calcine the filter cake to obtain primary titanium dioxide. The concentration of the first slurry, calculated as titanium dioxide, is 320-420 g / L. The amount of potassium hydroxide solution added is calculated as potassium oxide, the amount of phosphoric acid solution added is calculated as phosphorus pentoxide, and the amount of aluminum sulfate solution added is calculated as aluminum oxide. The mass of potassium oxide, phosphorus pentoxide, and aluminum oxide are 0.08-0.15%, 0.25-0.4%, and 0.4-0.8% of the mass of titanium dioxide in the first slurry, respectively.

[0007] In some embodiments, in step 5, the ammonium salt solution is titanium ammonium sulfate, and the mass of titanium ammonium sulfate is 0.4 to 1.2% of the mass of titanium dioxide in the first slurry.

[0008] In some embodiments, in step 5, the ammonium salt solution is ammonium sulfate, and the mass of ammonium sulfate is 0.5 to 1.5% of the mass of titanium dioxide in the first slurry.

[0009] In some embodiments, in step 5, the ammonium salt solution is titanium ammonium sulfate and ammonium sulfate, wherein the mass of titanium ammonium sulfate is 0.2 to 0.6% of the mass of titanium dioxide in the metatitanic acid slurry, and the mass of ammonium sulfate is 0.25 to 0.75% of the mass of titanium dioxide in the metatitanic acid slurry.

[0010] In some embodiments, step 7 includes: calcining the filter cake using a segmented heating and heat preservation method. In some embodiments, in step 1, the stirring speed is 800~1200 r / min and the stirring time is 30~60 min.

[0011] In some embodiments, in steps 2 to 5, the stirring speed is 400 to 600 r / min and the stirring time is 15 to 25 min.

[0012] In some embodiments, in step 6, the filtration is performed using a plate and frame filter, and the filtration pressure is 0.3~0.5MPa.

[0013] In some embodiments, the moisture content of the filter cake is 35-45%.

[0014] On the other hand, the disclosed embodiments also provide a primary titanium dioxide product for plastics, which is prepared using the above-described preparation method.

[0015] By adopting the above technical solution, this disclosure has at least the following beneficial effects: This invention discloses a method for preparing a primary titanium dioxide product for plastics and the primary titanium dioxide product for plastics. The preparation method controls the process parameters and reagent ratios of each step and adopts a composite modification system of potassium hydroxide, phosphoric acid, aluminum sulfate and ammonium salt to achieve particle size refinement and color optimization of the primary titanium dioxide product. The prepared primary titanium dioxide product has small and uniform particle size, low b value, high SCX value and bluish hue, in order to meet the needs of the plastics industry. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure or 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 only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of a method for preparing a primary titanium dioxide product for plastics according to an embodiment of the present disclosure. Detailed Implementation

[0018] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0019] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0020] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0022] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0023] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0024] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0025] As mentioned in the background section, the preparation of titanium dioxide precursors often employs single or simple composite modification processes, which struggle to simultaneously meet the core requirements of small particle size, low b-value, and a bluish hue. Furthermore, the process parameters are not precise enough, resulting in poor adaptability of the prepared titanium dioxide precursors and failing to meet the usage requirements of the plastics industry. Based on the above, this disclosure provides a method for preparing a plastic-specific titanium dioxide precursor and the prepared titanium dioxide precursor itself. The preparation method, by controlling the process parameters and reagent ratios at each step, utilizes a composite modification system of potassium hydroxide, phosphoric acid, aluminum sulfate, and ammonium salts to achieve particle size refinement and hue optimization of the titanium dioxide precursor. The resulting titanium dioxide precursor has small and uniform particle size, low b-value, high SCX value, and a bluish hue, thus meeting the usage requirements of the plastics industry.

[0026] This disclosure provides a method for preparing a primary titanium dioxide product for plastics, such as... Figure 1 As shown, it includes the following steps: Step 1: Mix the deionized water and metatitanic acid, stir well to obtain the first slurry; Step 2: Add potassium hydroxide solution to the first slurry and stir well to obtain the second slurry; Step 3: Add phosphoric acid solution to the second slurry and stir well to obtain the third slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir well to obtain the fourth slurry; Step 5: Add ammonium salt solution to the fourth slurry, stir well, and obtain the fifth slurry; Step 6: Filter the fifth slurry to obtain a filter cake; Step 7: Calcine the filter cake to obtain the initial titanium dioxide product.

[0027] The concentration of the first slurry, calculated as titanium dioxide, is 320-420 g / L. The amount of potassium hydroxide solution added is calculated as potassium oxide, the amount of phosphoric acid solution added is calculated as phosphorus pentoxide, and the amount of aluminum sulfate solution added is calculated as aluminum oxide. The mass of potassium oxide, phosphorus pentoxide, and aluminum oxide are 0.08-0.15%, 0.25-0.4%, and 0.4-0.8% of the mass of titanium dioxide in the first slurry, respectively.

[0028] The process principle is as follows: A slurry of specific concentration (320-420 g / L as titanium dioxide) was prepared by uniformly dispersing metatitanic acid using demineralized water. This provided a homogeneous and stable reaction system for subsequent modification reactions, ensuring sufficient contact between the reagents and metatitanic acid. A small amount of potassium hydroxide (calculated as potassium oxide) was added to adjust the pH of the slurry and to provide a small amount of potassium ions to the surface of the metatitanic acid, assisting in the subsequent crystal growth control and laying the foundation for the preparation of small-particle-size titanium dioxide. Phosphoric acid (calculated as phosphorus pentoxide) was used as a modifier to inhibit the agglomeration of metatitanic acid particles and refine the particle size. The particle size is reduced, and the hue of the raw titanium dioxide is improved, the b-value is reduced, and the blue phase tendency is enhanced. Aluminum sulfate (calculated as aluminum oxide) can form a thin aluminum oxide coating layer on the surface of metatitanic acid particles, further inhibiting particle growth, improving particle dispersibility, ensuring uniform particle size, and optimizing the physical properties of the raw product. Ammonium salts (titanium ammonium sulfate, ammonium sulfate, or a mixture of both) can be used as calcination aids to reduce the subsequent calcination temperature, inhibit excessive growth of titanium dioxide crystals, and help regulate particle morphology, further improving the blue phase characteristics and dispersion uniformity of the raw product.

[0029] Compared with existing technologies, this disclosure proposes a method for preparing highly active micro powder. Using high-silicon aluminum industrial solid waste as the main raw material, combined with industrial by-product waste acid and sodium sulfate, highly active micro powder is prepared through simple process steps. This realizes the resource utilization of industrial solid waste and industrial by-products, solves the problems of insufficient supply of highly active micro powder in the Panxi region, environmental pollution from industrial solid waste stockpiling, and difficulties in the disposal of industrial by-products. At the same time, it reduces the production cost of highly active micro powder and enhances the market competitiveness of the product.

[0030] In the above method, in step 5, the ammonium salt solution is titanium ammonium sulfate, and the mass of titanium ammonium sulfate is 0.4~1.2% of the mass of titanium dioxide in the first slurry. Titanium ammonium sulfate can play a role in assisting calcination, inhibiting excessive growth of titanium dioxide crystals, and at the same time helping to optimize the color of the product, providing support for the preparation of titanium dioxide primary products with a bluish phase and small particle size.

[0031] In the above method, in step 5, the ammonium salt solution is ammonium sulfate, and the mass of ammonium sulfate is 0.5~1.5% of the mass of titanium dioxide in the first slurry. As a calcining aid, ammonium sulfate can reduce the subsequent calcination temperature and avoid the introduction of impurities, thus ensuring product purity.

[0032] In the above method, in step 5, the ammonium salt solution is titanium ammonium sulfate and ammonium sulfate. The mass of titanium ammonium sulfate is 0.2~0.6% of the mass of titanium dioxide in the metatitanic acid slurry, and the mass of ammonium sulfate is 0.25~0.75% of the mass of titanium dioxide in the metatitanic acid slurry. Through the synergistic effect of the two ammonium salts, both the calcination aid effect and color control are taken into account.

[0033] In the above method, step 7 includes: calcining the filter cake using a segmented heating and holding method. By using a segmented heating and holding method, uneven calcination of the filter cake and excessive crystal growth are avoided, ensuring that the crystal morphology of the initial titanium dioxide product is uniform.

[0034] In the above method, in step 1, the stirring speed is 800~1200 r / min, and the stirring time is 30~60 min. High-speed stirring ensures that the metatitanic acid and deionized water are fully mixed and uniformly dispersed, avoiding the agglomeration of metatitanic acid particles. This provides a uniform and stable system for the subsequent reaction of reagents with metatitanic acid, ensuring the modification effect.

[0035] In the above method, the stirring speed is 400-600 r / min and the stirring time is 15-25 min in steps 2 to 5. The stirring speed after each reagent is added in steps 2 to 5 ensures that each reagent is fully mixed with the slurry and reacts completely. This avoids particle breakage caused by stirring too fast and incomplete reaction caused by stirring too slow, thus ensuring the stability of the effect of each modification step.

[0036] In the above method, in step 6, plate and frame filtration is used, and the filtration pressure is 0.3~0.5MPa. Plate and frame filtration has high filtration efficiency and good filter cake formation. Appropriate filtration pressure can ensure sufficient filtration, while avoiding the filter cake being too dry or too wet, providing a suitable filter cake state for subsequent calcination processes.

[0037] In the above method, the moisture content of the filter cake is 35-45%. This moisture content range ensures that the moisture evaporates slowly during the subsequent calcination process, avoiding cracking of the filter cake and uneven crystal growth caused by excessively rapid evaporation. At the same time, it reduces calcination energy consumption and ensures the stable quality of the initial titanium dioxide product.

[0038] On the other hand, the disclosed embodiments also provide a primary titanium dioxide product for plastics, which is prepared using the above-described preparation method.

[0039] The technical solution of the present invention will be further described below through specific embodiments.

[0040] Example 1: Step 1: Mix the deionized water and metatitanic acid, and stir at 800 r / min for 30 min until homogeneous to obtain a first slurry with a concentration of 320 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 400 r / min for 15 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.08% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 400 r / min for 15 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.25% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 400 r / min for 15 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.4% of the mass of titanium dioxide in the first slurry; Step 5: Add ammonium titanium sulfate solution to the fourth slurry and stir at 400 r / min for 15 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium titanium sulfate is 0.4% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.3 MPa to obtain a filter cake with a moisture content of 35%. Step 7: The filter cake is calcined using a segmented heating and holding method to obtain the initial titanium dioxide product. The specific calcination process is as follows: 30 min to raise the temperature from room temperature to 105℃ and hold for 120 min; 240 min to raise the temperature from 105℃ to 500℃ and hold for 120 min; 100 min to raise the temperature from 500℃ to 800℃ and hold for 120 min; 95 min to raise the temperature from 800℃ to 950℃ and hold for 110 min, and then the calcination is completed.

[0041] Example 2: Step 1: Mix the deionized water and metatitanic acid, and stir at 1000 r / min for 45 min until homogeneous to obtain a first slurry with a concentration of 360 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 500 r / min for 20 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.12% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 500 r / min for 20 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.3% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 500 r / min for 20 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.6% of the mass of titanium dioxide in the first slurry; Step 5: Add ammonium titanium sulfate solution to the fourth slurry, stir at 500 r / min for 20 min until homogeneous, and obtain the fifth slurry; wherein, the mass of ammonium titanium sulfate is 0.8% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.4 MPa to obtain a filter cake with a moisture content of 40%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0042] Example 3: Step 1: Mix the deionized water and metatitanic acid, and stir at 1200 r / min for 60 min until homogeneous to obtain a first slurry with a concentration of 420 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 600 r / min for 25 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.15% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 600 r / min for 25 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.4% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 600 r / min for 25 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.8% of the mass of titanium dioxide in the first slurry; Step 5: Add ammonium titanium sulfate solution to the fourth slurry and stir at 600 r / min for 25 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium titanium sulfate is 1.2% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.5 MPa to obtain a filter cake with a moisture content of 45%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0043] Example 4: Step 1: Mix the deionized water and metatitanic acid, and stir at 800 r / min for 30 min until homogeneous to obtain a first slurry with a concentration of 320 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 400 r / min for 15 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.08% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 400 r / min for 15 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.25% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 400 r / min for 15 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.4% of the mass of titanium dioxide in the first slurry; Step 5: Add ammonium sulfate solution to the fourth slurry and stir at 400 r / min for 15 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium sulfate is 0.5% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.3 MPa to obtain a filter cake with a moisture content of 35%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0044] Example 5: Step 1: Mix the deionized water and metatitanic acid, and stir at 1000 r / min for 45 min until homogeneous to obtain a first slurry with a concentration of 360 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 500 r / min for 20 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.12% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 500 r / min for 20 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.3% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 500 r / min for 20 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.6% of the mass of titanium dioxide in the first slurry; Step 5: Add ammonium sulfate solution to the fourth slurry and stir at 500 r / min for 20 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium sulfate is 1.0% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.4 MPa to obtain a filter cake with a moisture content of 40%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0045] Example 6: Step 1: Mix the deionized water and metatitanic acid, and stir at 1200 r / min for 60 min until homogeneous to obtain a first slurry with a concentration of 420 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 600 r / min for 25 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.15% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 600 r / min for 25 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.4% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 600 r / min for 25 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.8% of the mass of titanium dioxide in the first slurry; Step 5: Add ammonium sulfate solution to the fourth slurry and stir at 600 r / min for 25 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium sulfate is 1.5% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.5 MPa to obtain a filter cake with a moisture content of 45%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0046] Example 7: Step 1: Mix the deionized water and metatitanic acid, and stir at 800 r / min for 30 min until homogeneous to obtain a first slurry with a concentration of 320 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 400 r / min for 15 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.08% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 400 r / min for 15 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.25% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 400 r / min for 15 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.4% of the mass of titanium dioxide in the first slurry; Step 5: Add a mixed solution of ammonium titanium sulfate and ammonium sulfate to the fourth slurry, and stir at 400 r / min for 15 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium titanium sulfate is 0.2% of the mass of titanium dioxide in the first slurry, and the mass of ammonium sulfate is 0.25% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.3 MPa to obtain a filter cake with a moisture content of 35%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0047] Example 8: Step 1: Mix the deionized water and metatitanic acid, and stir at 1000 r / min for 45 min until homogeneous to obtain a first slurry with a concentration of 360 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 500 r / min for 20 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.12% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 500 r / min for 20 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.3% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 500 r / min for 20 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.6% of the mass of titanium dioxide in the first slurry; Step 5: Add a mixed solution of ammonium titanium sulfate and ammonium sulfate to the fourth slurry, and stir at 500 r / min for 20 min until homogeneous to obtain the fifth slurry; wherein the mass of ammonium titanium sulfate is 0.4% of the mass of titanium dioxide in the first slurry, and the mass of ammonium sulfate is 0.5% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.4 MPa to obtain a filter cake with a moisture content of 40%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0048] Example 9: Step 1: Mix the deionized water and metatitanic acid, and stir at 1200 r / min for 60 min until homogeneous to obtain a first slurry with a concentration of 420 g / L based on titanium dioxide. Step 2: Add potassium hydroxide solution to the first slurry and stir at 600 r / min for 25 min until homogeneous to obtain the second slurry; wherein, the amount of potassium hydroxide solution added is based on potassium oxide, and the mass of potassium oxide is 0.15% of the mass of titanium dioxide in the first slurry; Step 3: Add phosphoric acid solution to the second slurry and stir at 600 r / min for 25 min until homogeneous to obtain the third slurry; wherein, the amount of phosphoric acid solution added is based on phosphorus pentoxide, and the mass of phosphorus pentoxide is 0.4% of the mass of titanium dioxide in the first slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir at 600 r / min for 25 min until homogeneous to obtain the fourth slurry; wherein, the amount of aluminum sulfate solution added is based on aluminum oxide, and the mass of aluminum oxide is 0.8% of the mass of titanium dioxide in the first slurry; Step 5: Add a mixed solution of ammonium titanium sulfate and ammonium sulfate to the fourth slurry, and stir at 600 r / min for 25 min until homogeneous to obtain the fifth slurry; wherein, the mass of ammonium titanium sulfate is 0.6% of the mass of titanium dioxide in the first slurry, and the mass of ammonium sulfate is 0.75% of the mass of titanium dioxide in the first slurry; Step 6: The fifth slurry is filtered using a plate and frame filter press at a pressure of 0.5 MPa to obtain a filter cake with a moisture content of 45%. Step 7: The filter cake is calcined using a segmented heating and heat preservation method to obtain the initial titanium dioxide product; the specific calcination process is the same as in Example 1.

[0049] After the titanium dioxide primary products obtained in Examples 1-9 were pulverized, SEM and slurry hue tests were performed. The results are shown in Table 1. The average particle size of the product was between 185 and 211 nm, the b value (yellow-blue hue value) was between -2.26 and -1.96 (leaning towards blue), and the SCX value (hue value) was between 2.21 and 2.68. The particle size was uniform and fully met the requirements for primary titanium dioxide for plastics.

[0050] Table 1. Detection results of particle size and distribution of the initial products and mortar color obtained in Examples 1-9.

[0051] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0052] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A method for preparing a primary titanium dioxide product for plastics, characterized in that, Includes the following steps: Step 1: Mix the deionized water and metatitanic acid, stir well to obtain the first slurry; Step 2: Add potassium hydroxide solution to the first slurry and stir until homogeneous to obtain the second slurry; Step 3: Add phosphoric acid solution to the second slurry and stir until homogeneous to obtain the third slurry; Step 4: Add aluminum sulfate solution to the third slurry and stir until homogeneous to obtain the fourth slurry; Step 5: Add ammonium salt solution to the fourth slurry and stir evenly to obtain the fifth slurry; Step 6: Filter the fifth slurry to obtain a filter cake; Step 7: Calcine the filter cake to obtain primary titanium dioxide. The concentration of the first slurry, calculated as titanium dioxide, is 320-420 g / L; the amount of potassium hydroxide solution added is calculated as potassium oxide, the amount of phosphoric acid solution added is calculated as phosphorus pentoxide, and the amount of aluminum sulfate solution added is calculated as aluminum oxide; the mass of potassium oxide, phosphorus pentoxide, and aluminum oxide are 0.08-0.15%, 0.25-0.4%, and 0.4-0.8% of the mass of titanium dioxide in the first slurry, respectively.

2. The method for preparing primary titanium dioxide for plastics according to claim 1, characterized in that, In step 5, the ammonium salt solution is titanium ammonium sulfate, and the mass of titanium ammonium sulfate is 0.4~1.2% of the mass of titanium dioxide in the first slurry.

3. The method for preparing primary titanium dioxide for plastics according to claim 1, characterized in that, In step 5, the ammonium salt solution is ammonium sulfate, and the mass of ammonium sulfate is 0.5 to 1.5% of the mass of titanium dioxide in the first slurry.

4. The method for preparing the primary titanium dioxide product for plastics according to claim 1, characterized in that, In step 5, the ammonium salt solution is titanium ammonium sulfate and ammonium sulfate. The mass of titanium ammonium sulfate is 0.2~0.6% of the mass of titanium dioxide in the metatitanic acid slurry, and the mass of ammonium sulfate is 0.25~0.75% of the mass of titanium dioxide in the metatitanic acid slurry.

5. The method for preparing primary titanium dioxide for plastics according to claim 1, characterized in that, Step 7 includes: calcining the filter cake using a segmented heating and heat preservation method.

6. The method for preparing primary titanium dioxide for plastics according to claim 1, characterized in that, In step 1, the stirring speed is 800~1200 r / min and the stirring time is 30~60 min.

7. The method for preparing primary titanium dioxide for plastics according to claim 1, characterized in that, In steps 2 through 5, the stirring speed is 400-600 r / min and the stirring time is 15-25 min.

8. The method for preparing the primary titanium dioxide for plastics according to claim 1, characterized in that, In step 6, plate and frame filtration is used, and the filtration pressure is 0.3~0.5MPa.

9. The method for preparing the primary titanium dioxide for plastics according to claim 8, characterized in that, The moisture content of the filter cake is 35-45%.

10. A primary titanium dioxide product for plastics, characterized in that, include: It is prepared using the preparation method described in any one of claims 1-9.

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