Process for preparing high-purity titanium dioxide from metatitanic acid

Abstract

The application discloses a process for preparing high-purity titanium dioxide from metatitanic acid, and relates to the technical field of titanium dioxide preparation.The process comprises the following steps: adding water to a primary metatitanic acid filter cake obtained by leaching ilmenite powder, and performing acid dissolution; using a composite reducing agent to strengthen reduction treatment; performing hot washing, salt treatment, drying and calcination, so as to obtain high-purity titanium dioxide.The titanium dioxide obtained by the process has an iron content of less than 10 ppm, a whiteness analysis L value of more than 98%, and stable yellow-blue value (b value).The process is based on the sulfuric acid method titanium dioxide production technology, and provides a complete process technology for producing high-quality titanium dioxide with simple process, convenient operation, low cost and low pollution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium dioxide production, more particularly to the technical field of preparing high-purity titanium dioxide from metatitanic acid. High-purity titanium dioxide is finally produced through reduction treatment. BACKGROUND

[0002] Titanium dioxide is an important inorganic chemical pigment, which is widely used in the fields of coatings, inks, papermaking, plastics and rubbers, chemical fibers, ceramics, etc. The main component of titanium dioxide is titanium dioxide. There are two process routes for the production of titanium dioxide, namely the sulfuric acid method and the chlorination method. The sulfuric acid method is mainly used in the production of titanium dioxide in China. In the process, a reducing agent is used to bleach metatitanic acid to reduce ferric ions, thereby improving the whiteness and gloss of the titanium dioxide product. The following technologies are disclosed in existing patents:

[0003] The patent with the publication number CN115350774A and the patent name "Titanium dioxide, titanium dioxide production process and powder grinding process in titanium dioxide production" discloses the following content: to solve the problem of additional cooling treatment of the ball mill and cooling of the material after ball milling in the prior art, a powder grinding process in titanium dioxide production is characterized in that the specific process flow of the powder grinding is: mixing dry titanium concentrate and wet titanium concentrate to obtain a mixture; the mixture enters the ball mill for grinding to obtain a fine material. The titanium dioxide production process provided by the present application has high utilization rate of titanium concentrate; no additional cooling device is needed to reduce the temperature of the ball mill; the material after ball milling can be directly acidified; and the wet ore does not need additional drying cost.

[0004] The patent with the publication number CN106745229B and the patent name "Preparation process of pharmaceutical-grade titanium dioxide" discloses the following content: the high-titanium slag titanium liquid production method solves the technical problems of low titanium-iron ratio and high impurities in ilmenite, and achieves the technical effects of low cost and high quality of titanium liquid production; the alkali method titanium dioxide production process uses NaOH salt solution and sulfuric acid solution to react with high-titanium slag, which achieves the technical effect of obtaining sulfuric acid titanium solution with different F values and mass concentrations by controlling the mass fraction of sulfuric acid and the acid-solid mass ratio; and the technical method of adding aluminum alloy additives during the hydrolysis process achieves the technical effects of improving the hiding power, dispersibility and light resistance of titanium dioxide, and increasing the stability of titanium dioxide.

[0005] However, the above-mentioned patents and traditional methods mainly use trivalent titanium / aluminum powder (or zinc powder) for bleaching, which has high cost, slow mass transfer and diffusion, and low bleaching efficiency. Organic reduction bleaching technology can improve the mass transfer coefficient and reduction bleaching efficiency, and reduce the comprehensive use cost. However, when using organic reducing agents alone, problems such as abnormal increase of L value (lightness) and yellow-blue value (b) of titanium dioxide may occur. SUMMARY

[0006] The present application aims at solving the above technical problems, and provides a process for preparing high-purity titanium dioxide from metatitanic acid.

[0007] To achieve the above-mentioned purposes, the present application specifically adopts the following technical solutions:

[0008] The present application provides a process for preparing high-purity titanium dioxide from metatitanic acid, comprising the following steps:

[0009] S1, preparation of metatitanic acid crude slurry: adding pure water to the primary metatitanic acid filter cake obtained by leaching ilmenite powder, and obtaining metatitanic acid crude slurry by stirring;

[0010] S2, slurry dissolution: adding sulfuric acid to the metatitanic acid crude slurry, heating and stirring, and obtaining metatitanic acid slurry after cooling;

[0011] S3, slurry reduction: adding trivalent titanium solution and a composite reducing agent to the metatitanic acid slurry, and fully stirring to reduce the trivalent iron ions in the metatitanic acid slurry, thereby obtaining a reduced slurry;

[0012] S4, filtration and washing: filtering the reduced slurry obtained in step S3, and washing the reduced slurry with hot water multiple times, thereby obtaining a secondary filter cake;

[0013] S5, salt treatment: adding pure water to the secondary filter cake obtained in step S4, stirring while heating, adding phosphoric acid, potassium hydroxide and zinc oxide, and fully stirring to obtain a salt-treated slurry;

[0014] S6, drying and calcination: further filtering, drying and calcining the salt-treated slurry obtained in step S5 to obtain high-purity titanium dioxide.

[0015] In one embodiment, in step S1, the TiO2 content in the metatitanic acid crude slurry is 200 g / L-350 g / L.

[0016] In one embodiment, in step S2, the amount of sulfuric acid added is 5%-15% of the TiO2 content to ensure sufficient dissolution of the metatitanic acid, the stirring temperature is 80-120℃, and the stirring time is 1-5 hours.

[0017] In one embodiment, in step S3, the amount of trivalent titanium solution added is 0.1%-0.5% of the TiO2 content.

[0018] In one embodiment, in step S3, the composite reducing agent is one or more of sodium borohydride, sodium sulfite, formaldehyde solution and sodium hydrosulfite formaldehyde.

[0019] In one embodiment, in step S3, the composite reducing agent is added in an amount of 0.05%-0.5% of the TiO2 content, the reduction temperature is 30-50°C, and the reduction time is 1-5 hours.

[0020] In one embodiment, in step S4, the temperature of the hot water is 50-80°C.

[0021] In one embodiment, in step S5, the phosphoric acid is added in an amount of 0.01%-0.2% of the TiO2 content.

[0022] In one embodiment, in step S5, the potassium hydroxide is added in an amount of 0.1%-0.5% of the TiO2 content, and the zinc oxide is added in an amount of 0.1%-0.5% of the TiO2 content.

[0023] In one embodiment, in step S6, the drying temperature is 110-150°C, the drying time is 2-8 hours, the calcination temperature is 600-1000°C, and the calcination time is 2-8 hours.

[0024] The beneficial effects of the present application are as follows:

[0025] 1. The TiO2 powder obtained by the process of the present application has an iron content of less than 10 ppm.

[0026] 2. The TiO2 powder obtained by the process of the present application has a whiteness analysis L value of greater than 98%, and a yellow-blue value (b value) that is stably maintained at 1.2-1.6.

[0027] 3. The process of the present application is simple and has strong operability, and the raw materials used are common chemical raw materials commonly found in the market, which can effectively reduce production costs. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is Figure 1 The process flow diagram for preparing high-purity titanium dioxide from metatitanic acid according to the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions will be described below in connection with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0030] The following detailed description of the embodiments is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0031] Example 1

[0032] like Figure 1 As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 200 g / L. Then, concentrated sulfuric acid (98% purity) was added at 5% of the TiO2 content, and the mixture was stirred at 80°C for 5 hours. Trivalent titanium solution was added at 0.1% of the TiO2 content, and stirring was maintained. A mixture of sodium borohydride and sodium bisulfite formaldehyde, with a mass ratio of 1:1, was added at a total amount of 0.05% of the TiO2 content, and the mixture was stirred at 50°C for 1 hour. The mixture was then filtered and washed three times with hot water at 50°C. Phosphoric acid, potassium hydroxide, and zinc oxide were added sequentially at 0.01% of the TiO2 content. The mixture was dried at 110°C for 8 hours and calcined at 1000°C for 2 hours to obtain titanium dioxide sample 1.

[0033] Example 2

[0034] like Figure 1 As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a rough metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 250 g / L. Then, concentrated sulfuric acid (98% purity) was added at 10% of the TiO2 content, and the mixture was stirred at 100°C for 3 hours. Trivalent titanium solution was added at 0.3% of the TiO2 content, and stirring was maintained. A mixture of formaldehyde solution and sodium formaldehyde bisulfite at a mass ratio of 1:1 was added, totaling 0.2% of the TiO2 content, and the mixture was stirred at 30°C for 3 hours. The mixture was then filtered and washed three times with hot water at 60°C. Phosphoric acid (0.05% of the TiO2 content), potassium hydroxide (0.3% of the TiO2 content), and zinc oxide (0.3% of the TiO2 content) were added sequentially. The mixture was dried at 120°C for 6 hours and calcined at 900°C for 4 hours to obtain titanium dioxide sample 2.

[0035] Example 3

[0036] like Figure 1As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a rough metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 300 g / L. Then, concentrated sulfuric acid (98% purity) was added, at a rate of 15% of the TiO2 content, and the mixture was stirred at 120°C for 1 hour. Trivalent titanium solution was added, at a rate of 0.5% of the TiO2 content, and stirring was maintained. A mixture of formaldehyde solution, sodium sulfite, and sodium bisulfite formaldehyde, in a mass ratio of 1:1:1, was added, at a total amount of 0.5% of the TiO2 content, and the mixture was stirred at 50°C for 1 hour. The mixture was then filtered and washed three times with hot water at 80°C. Phosphoric acid (0.2% of the TiO2 content), potassium hydroxide (0.5% of the TiO2 content), and zinc oxide (0.5% of the TiO2 content) were added sequentially. The sample was dried at 150℃ for 2 hours and calcined at 800℃ for 2 hours to obtain titanium dioxide sample 3.

[0037] Example 4

[0038] like Figure 1 As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a rough metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 350 g / L. Then, concentrated sulfuric acid (98% purity) was added, at a rate of 15% of the TiO2 content, and the mixture was stirred at 120°C for 2 hours. Trivalent titanium solution was added, at a rate of 0.5% of the TiO2 content, and stirring was maintained. A mixture of sodium borohydride, formaldehyde solution, sodium sulfite, and sodium bisulfite formaldehyde was added in a mass ratio of 1:1:1:1, at a total amount of 0.5% of the TiO2 content, and the mixture was stirred at 50°C for 2 hours. The mixture was then filtered and washed three times with hot water at 70°C. Phosphoric acid, potassium hydroxide, and zinc oxide were added sequentially, at a rate of 0.1% of the TiO2 content. The sample was dried at 110℃ for 8 hours and calcined at 600℃ for 8 hours to obtain titanium dioxide sample 4.

[0039] Example 5

[0040] like Figure 1As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 250 g / L. Then, concentrated sulfuric acid (98% purity) was added at 8% of the TiO2 content, and the mixture was stirred at 110°C for 3 hours. Trivalent titanium solution was added at 0.2% of the TiO2 content, and stirring was maintained. A mixture of sodium borohydride and formaldehyde solution was added at a mass ratio of 1:1, totaling 0.2% of the TiO2 content, and the mixture was stirred at 50°C for 5 hours. The mixture was then filtered and washed three times with hot water at 60°C. Phosphoric acid (0.05% of the TiO2 content), potassium hydroxide (0.2% of the TiO2 content), and zinc oxide (0.2% of the TiO2 content) were added sequentially. The mixture was dried at 110°C for 8 hours and calcined at 800°C for 5 hours to obtain titanium dioxide sample 5.

[0041] Example 6

[0042] like Figure 1 As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 320 g / L. Then, concentrated sulfuric acid (98% purity) was added at 12% of the TiO2 content, and the mixture was stirred at 120°C for 3 hours. Trivalent titanium solution was added at 0.3% of the TiO2 content, and stirring was maintained. A mixture of formaldehyde and sodium formaldehyde sulfoxylate (1:1 mass ratio) was added at 0.2% of the TiO2 content, and the mixture was stirred at 50°C for 5 hours. The mixture was then filtered and washed three times with hot water at 50°C. Phosphoric acid (0.1% of the TiO2 content), potassium hydroxide (0.3% of the TiO2 content), and zinc oxide (0.3% of the TiO2 content) were added sequentially. The mixture was dried at 110°C for 8 hours and calcined at 800°C for 5 hours to obtain titanium dioxide sample 6.

[0043] Example 7

[0044] like Figure 1As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a rough metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 380 g / L. Then, concentrated sulfuric acid (98% purity) was added at 12% of the TiO2 content, and the mixture was stirred at 120°C for 3 hours. Trivalent titanium solution was added at 0.4% of the TiO2 content, and stirring was maintained. Sodium bisulfite and formaldehyde were added at 0.5% of the TiO2 content, and the mixture was stirred at 80°C for 1 hour. The mixture was then filtered and washed three times with hot water at 60°C. Phosphoric acid (0.01% of the TiO2 content), potassium hydroxide (0.1% of the TiO2 content), and zinc oxide (0.1% of the TiO2 content) were added sequentially. The mixture was dried at 120°C for 8 hours and calcined at 1000°C for 2 hours to obtain titanium dioxide sample 7.

[0045] Example 8

[0046] like Figure 1 As shown, pure water was added to the primary metatitanic acid filter cake obtained from leaching ilmenite powder, and the mixture was stirred at high speed for 1 hour to obtain a metatitanic acid slurry. The amount of water added was sufficient to ensure that the TiO2 content in the slurry was 380 g / L. Then, concentrated sulfuric acid (98% purity) was added at 12% of the TiO2 content, and the mixture was stirred at 120°C for 3 hours. Trivalent titanium solution was added at 0.4% of the TiO2 content, and stirring was maintained. Formaldehyde was added at 0.5% of the TiO2 content, and the mixture was stirred at 80°C for 1 hour. The mixture was then filtered and washed three times with hot water at 60°C. Phosphoric acid (0.01% of the TiO2 content), potassium hydroxide (0.1% of the TiO2 content), and zinc oxide (0.1% of the TiO2 content) were added sequentially. The mixture was dried at 120°C for 8 hours and calcined at 1000°C for 2 hours to obtain titanium dioxide sample 8.

[0047] The iron content in samples 1-8 was analyzed using ICP-MASS, and the L-value and b-value of titanium dioxide whiteness were determined. The results are shown in the table below:

[0048]

[0049] Conclusion: As can be seen from the table above, the titanium dioxide samples prepared by the process of the present invention in Examples 1 to 8 all have an iron content of less than 10 ppm, a whiteness analysis L value of better than 98%, and a stable yellow-blue value (b value) (stable between 1.32 and 1.52).

Claims

1. A process for the preparation of high purity titanium dioxide from metatitanic acid, characterized in that, Includes the following steps: S1. Preparation of metatitanic acid coarse slurry: Using the primary metatitanic acid filter cake obtained by leaching ilmenite powder as raw material, pure water is added and stirred to obtain metatitanic acid coarse slurry; S2. Slurry dissolution: Add sulfuric acid to the raw metatitanic acid slurry, heat and stir, and then cool to obtain metatitanic acid slurry; S3. Slurry Reduction: Add trivalent titanium solution and composite reducing agent to metatitanic acid slurry, and stir thoroughly to reduce the trivalent iron ions in metatitanic acid slurry to obtain reduced slurry; the composite reducing agent is one or more of sodium borohydride, sodium sulfite, formaldehyde solution and sodium bisulfite formaldehyde; the amount of composite reducing agent added is 0.05%-0.5% of TiO2 content, the reduction temperature is 30℃-50℃, and the reduction time is 1-5 hours; S4. Filtration and washing: The reducing slurry obtained in step S3 is filtered and washed multiple times with hot water to obtain a secondary filter cake. S5. Salt treatment: Add pure water to the secondary filter cake obtained in step S4 again, heat and stir at the same time, add phosphoric acid, potassium hydroxide and zinc oxide, stir thoroughly to obtain salt treatment slurry; S6. Drying and calcining: The salt-treated slurry obtained in step S5 is further filtered, dried, and calcined to obtain high-purity titanium dioxide.

2. The process for preparing high purity titanium dioxide from metatitanic acid according to claim 1, characterized in that, In step S1, the TiO2 content in the metatitanic acid slurry is 200 g / L-350 g / L.

3. The process for preparing high purity titanium dioxide from metatitanic acid as claimed in claim 1, wherein, In step S2, the amount of sulfuric acid added is 5%-15% of the TiO2 content to ensure the full dissolution of metatitanic acid. The stirring temperature is 80-120 ℃ and the stirring time is 1-5 hours.

4. The process for preparing high purity titanium dioxide from metatitanic acid as claimed in claim 1, wherein, In step S3, the amount of trivalent titanium solution added is 0.1%-0.5% of the TiO2 content.

5. The process for preparing high purity titanium dioxide from metatitanic acid as claimed in claim 1, wherein, In step S4, the temperature of the washing hot water is 50℃-80℃.

6. The process for preparing high purity titanium dioxide from metatitanic acid as claimed in claim 1, wherein, In step S5, the amount of phosphoric acid added is 0.01%-0.2% of the TiO2 content.

7. The process for preparing high purity titanium dioxide from metatitanic acid as claimed in claim 1, wherein, In step S5, the amount of potassium hydroxide added is 0.1%-0.5% of the TiO2 content, and the amount of zinc oxide added is 0.1%-0.5% of the TiO2 content.

8. The process for preparing high purity titanium dioxide from metatitanic acid as claimed in claim 1, wherein, In step S6, the drying temperature is 110℃-150℃, the drying time is 2h-8h, the calcination temperature is 600℃-1000℃, and the calcination time is 2h-8h.

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