High-purity titanium dioxide and a method for producing the same

Abstract

The application discloses high-purity titanium dioxide and a preparation method thereof, and comprises the following steps: crushing, grinding, and sieving titanium-containing blast furnace slag, mixing the slag with a sulfuric acid solution, adding a modified complexing agent and a surfactant, heating and reacting to obtain acidolysis slag, adding the acidolysis slag into deionized water, stirring and mixing to obtain a titanium oxysulfate solution containing impurities, adding the solution into a reaction kettle, sealing and reacting to obtain hydrothermal metatitanic acid, mixing the metatitanic acid with a NaOH solution to prepare slurry, adjusting pH, stirring at room temperature, filtering, washing, and drying the product to obtain desulfurized metatitanic acid, roasting, and cooling to obtain the high-purity titanium dioxide; the method can effectively remove impurities in the titanium-containing blast furnace slag, improve the product quality of the prepared titanium dioxide, reduce the use amount of acid, and reduce the environmental pollution risk.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium dioxide, and particularly relates to high-purity titanium dioxide and a preparation method thereof. BACKGROUND

[0002] Titanium-bearing furnace slag (TBFS) is a by-product of blast furnace smelting of vanadium-titanium magnetite and is a valuable titanium resource that needs to be developed. During blast furnace smelting, the unreduced titanium, silicon, calcium, magnesium, aluminum and other oxides are co-melted with vanadium-containing molten iron, titanium carbide and titanium nitride at 1385-1440 DEG C and crystallize and solidify at 1000-1200 DEG C to form TBFS.

[0003] The main mineral composition of TBFS is perovskite and pargasite, and a small amount of titanium-rich diopside, magnesium-aluminum spinel, titanium carbide and titanium nitride. The titanium resources are dispersedly distributed in various mineral phases, the titanium-containing mineral grains are small (about 10 microns), the distribution is chaotic, and the titanium-containing mineral grains are connected with each other. The traditional beneficiation and smelting technology cannot realize the separation of the titanium-containing components and the slag phase, only a small part is used to prepare low-end building materials (such as slag cement, sanitary ceramic plate and alkali-resistant mineral wool), and a large amount of titanium-containing blast furnace slag is in an idle state. At present, the total accumulation amount has exceeded 80 million tons, and is increasing at a rate of more than 3.8 million tons per year. The sustainable development of the vanadium-titanium industry is facing great environmental pressure, and it is urgent to solve the bottleneck of TBFS utilization through technological innovation and promote the large-scale green high-value comprehensive utilization.

[0004] The research on the preparation of titanium alloy or nano-titanium dioxide by TBFS mainly includes two basic ideas: pyrometallurgical method (high-temperature carbonization-low-temperature chlorination, alkali roasting, and metal hot reduction) and hydrometallurgical method (hydrochloric acid and sulfuric acid). The high-temperature carbonization-low-temperature chlorination method uses carbon and TBFS as raw materials, which are carbonized at 1580-1700°C, chlorinated at 400-600°C, removed from the alum, rectified, and oxidized to obtain high-purity TiO2. This method is suitable for processing hot TBFS, has high requirements for corrosion-resistant equipment, and has difficulty in processing chlorine-containing residues, so it has not been applied in industry. The alkali roasting method uses alkaline substances such as sodium hydroxide to react with TBFS at 200-700°C, and the product is obtained by water washing, acid dissolution, hydrolysis, and calcination. This method has high acid and alkali consumption, high sodium salt recovery cost, complex process flow, and high requirements for equipment, and is currently in the experimental research and development stage. The metal hot reduction method uses TBFS as raw material and silicon-iron alloy or silicon-aluminum-iron alloy as reducing agent to prepare titanium-silicon or titanium-iron alloy through high-temperature melting and recasting. This method has a short process flow, strong adaptability to raw materials, but high cost, high energy consumption, and small application market, and has not been industrialized. The hydrochloric acid method mixes hydrochloric acid and TBFS at 80-130°C for acid hydrolysis for 4-20 hours, and then filters, distills, hydrolyzes at normal pressure, and calcines to obtain TiO2. This method requires high acid concentration (>30%) and high corrosion-resistant equipment, and has difficulty in treating chlorine-containing wastewater, so it has not been applied in industry. The sulfuric acid method uses sulfuric acid to react with TBFS to obtain titanium sulfate (TiOSO4) solution, which is filtered, distilled, hydrolyzed at normal pressure, and calcined to obtain TiO2. The sulfuric acid method for treating TBFS mainly includes liquid phase method and solid phase method, and the sulfuric acid-solid phase method is widely used in the industrial production of titanium dioxide from ilmenite. Therefore, this method has great application potential for preparing TiO2 from TBFS.

[0005] Chinese patent document CN117865217A discloses a method for preparing titanium dioxide using titanium-rich material as raw material, comprising the following steps: S1, roasting and nitric acid pressure leaching of titanium-containing blast furnace slag to obtain blast furnace slag leaching solution and titanium-rich material; S2, mixing the titanium-rich material with concentrated sulfuric acid and adding an appropriate amount of water, then heat-treating and roasting at low temperature to form a loose and porous solid phase; S3, adding the solid phase to an appropriate amount of water and heating and stirring to leach, and then separating the solid and liquid to obtain leaching solution and leaching material; S4, preparing titanium dioxide by concentrating, reducing, hydrolyzing, and roasting the leaching solution.

[0006] In the existing sulfuric acid-solid phase method technology, the titanyl sulfate solution prepared from the titanium-containing blast furnace slag has significant differences compared with the industrial standard, mainly in the following aspects: the titanium concentration is low, the titanium content (calculated as TiO2) in the solution is usually less than 120 g / L; the impurity content is high, the magnesium sulfate (MgSO4) concentration exceeds 20 g / L, and the aluminum sulfate [Al2(SO4)3] concentration also exceeds 20 g / L; the process is limited, due to the limitation of the atmospheric hydrolysis condition, the low-concentration and high-impurity titanium liquid cannot be directly hydrolyzed, and needs to be purified and concentrated first, and then atmospheric autogenous or external seed hydrolysis operation can be carried out. These characteristics lead to a series of problems such as long production process, large energy consumption and low titanium recovery rate. Therefore, this method faces many challenges in industrial application, and it is difficult to be widely promoted. In order to make it have practical application value, further technical improvement and innovation are needed. SUMMARY

[0007] In order to solve the problems existing in the prior art, the purpose of the present application is to provide a high-purity titanium dioxide and a preparation method thereof, which can effectively remove impurities in titanium-containing blast furnace slag, improve the product quality of the prepared titanium dioxide, reduce the amount of acid used, and reduce the risk of environmental pollution.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0009] A high-purity titanium dioxide and a preparation method thereof, comprising the following steps:

[0010] (1) crushing, grinding and sieving the titanium-containing blast furnace slag;

[0011] (2) mixing the sieved titanium-containing blast furnace slag with a sulfuric acid solution, adding a modified complexing agent and a surfactant, heating and reacting to obtain acidolysis slag; adding the acidolysis slag into deionized water, stirring and mixing, filtering to obtain a titanium oxide solution containing impurities;

[0012] (3) adding the titanium oxide solution containing impurities into a reaction kettle, sealing the reaction, cooling and filtering the product to obtain a filter cake, washing and drying the filter cake to obtain metatitanic acid;

[0013] (4) mixing the metatitanic acid with a NaOH solution to prepare a slurry, adjusting the pH, stirring at room temperature, filtering, washing and drying the product to obtain desulfurized metatitanic acid; calcining and cooling the desulfurized metatitanic acid to obtain the high-purity titanium dioxide.

[0014] Preferably, in step (1), the titanium-containing blast furnace slag is sieved through a 200-600 mesh sieve.

[0015] Preferably, in step (2), the concentration of sulfuric acid solution is 85-98wt%; the heating reaction condition is 70-130℃ for 1-6h; the surfactant is one or more of anionic surfactant and non-ionic surfactant.

[0016] Preferably, in step (2), the ratio of titanium-containing blast furnace slag to sulfuric acid solution is 1:1.5-2.2; the amount of modified complexing agent and surfactant is 0.01-0.5wt% and 0.5-2wt% of titanium-containing blast furnace slag, respectively; the ratio of acidolysis slag to deionized water is 1:1-2.

[0017] Preferably, in step (3), the sealed reaction condition is hydrothermal reaction at 110-160℃ and 0.2-1MPa for 1-12h.

[0018] Preferably, in step (4), the concentration of NaOH solution is 0.5-5wt%, and the pH is adjusted to 10-14; the stirring condition at room temperature is 400-800r / min for 30-120min, and the drying condition is 100-110℃ for 1-3h; the calcination condition is 500-1000℃ in a muffle furnace for 2-5h.

[0019] Preferably, in step (2), the structural formula of the modified complexing agent is one of formula I or formula II:

[0020]

[0021] More preferably, in step (2), the structural formula of the modified complexing agent is as follows:

[0022]

[0023] Preferably, in step (2), the preparation method of the modified complexing agent comprises the following steps:

[0024] Add imino diacetic acid and potassium carbonate to tetrahydrofuran, slowly drop benzene tricarbonyl chloride under ice bath condition, stir the reaction under ice bath condition, remove the solvent tetrahydrofuran of the product by rotary evaporation, then extract and separate by adding ethyl acetate, rotary evaporation, recrystallize the product in ethyl acetate to obtain the modified complexing agent.

[0025] Preferably, the molar ratio of imino diacetic acid, potassium carbonate and benzene tricarbonyl chloride is 1:2.5-4:2-3.1.

[0026] Preferably, benzene tricarbonyl chloride is added dropwise for 30-90min, and the stirring reaction condition is 0-5℃ for 1-6h.

[0027] Under ice bath condition (0-5℃), iminodiacetic acid and potassium carbonate are mixed in tetrahydrofuran solvent, then trimesoyl chloride is slowly added dropwise, and the reaction is continuously stirred in ice bath, after the reaction is completed, tetrahydrofuran solvent is removed by rotary evaporator, then the product is separated by extraction with ethyl acetate, then ethyl acetate is removed again by rotary evaporator, and finally the final product modified complexing agent is obtained by recrystallization with ethyl acetate.

[0028] The core of the reaction is the acylation reaction between acyl chloride and amino group to generate N-substituted amide. Trimesoyl chloride contains three acyl chloride groups, which can undergo acylation reaction with the secondary amine group in iminodiacetic acid. The acylation reaction in this step is carried out under low temperature ice bath environment to slow down the reaction rate, thereby improving the product yield and reducing the occurrence of side reactions. Slowly adding trimesoyl chloride can ensure that the reaction is more thorough and avoid local excess to increase side reactions.

[0029] Potassium carbonate, as a basic substance, not only removes acidic impurities in raw materials, but also provides the basic environment required for the reaction, promoting the progress of the reaction. Potassium carbonate neutralizes by-products such as hydrochloric acid generated during the reaction, ensuring that the reaction medium remains alkaline.

[0030] In the post-processing step after the reaction is completed, tetrahydrofuran solvent is removed by rotary evaporator (rotary evaporation) to obtain the preliminary product. Subsequently, ethyl acetate is used to extract the reaction mixture to separate non-polar impurities, and then ethyl acetate is removed by rotary evaporation to obtain the refined product required for recrystallization. Finally, the product is further purified by recrystallization in ethyl acetate to ensure that the modified complexing agent generated finally has high purity.

[0031] The present application also claims a high-purity titanium dioxide prepared by the preparation method.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] 1) The present application provides a high-purity titanium dioxide and a preparation method thereof. The high-purity titanium dioxide is prepared from titanium-containing blast furnace slag by crushing, acidolysis, hydrothermal reaction and calcination, and is suitable for multiple industries such as coatings, plastics and papermaking. The addition of a surfactant during acidolysis can effectively prevent the agglomeration and sedimentation of titanium-containing blast furnace slag, and has a solubilizing effect on insoluble impurities, thereby improving the reaction efficiency of slag, sulfuric acid and modified complexing agent. The method provided by the present application can effectively remove impurities in titanium-containing blast furnace slag, improve the product quality of the prepared titanium dioxide, reduce the amount of acid used, and reduce the risk of environmental pollution.

[0034] 2) The application provides a modified complexing agent containing multiple carboxyl functional groups, which can selectively form stable complexes with impurity ions such as alkali metals and alkaline earth metals in blast furnace slag, significantly improving the solubility of impurities in an acidic solution, helping to efficiently separate impurities from the titanium-containing blast furnace slag, and obtaining a purer titanium product. Compared with the traditional strong acid leaching process, the use of modified complexing agent can reduce the amount of acid used, reduce the risk of environmental pollution, and also plays an important role in improving product quality and process efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiment schematic diagrams of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0036] Figure 1 SEM photo of high-purity titanium dioxide prepared in Example 1 of the application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the application more clear, the following will further describe the application in combination with the embodiments. Of course, the specific embodiments described here are only used to explain the application, and are not used to limit the application.

[0038] Unless otherwise specified, the chemical reagents and materials in the application are purchased through market channels or synthesized from raw materials purchased through market channels.

[0039] The titanium-containing blast furnace slag used in the examples and comparative examples is from a certain factory in China, and its chemical composition is shown in Table 1:

[0040] Table 1 Main composition of titanium-containing blast furnace slag

[0041]

[0042] A preparation method of high-purity titanium dioxide, comprising the following steps:

[0043] (1) 10 mmol iminodiacetic acid, 2.5-4 mmol potassium carbonate are added to 50 mL tetrahydrofuran, 2-3.1 mmol trimesoyl chloride is slowly added under ice bath condition, and the dropping is completed in 30-90 min, and the reaction is stirred under ice bath at 0-5℃ for 1-6 h, then the product is spin-evaporated to remove the solvent tetrahydrofuran, then ethyl acetate is added for extraction and separation, spin-evaporated, and the product is recrystallized in ethyl acetate to obtain the modified complexing agent;

[0044] (2) crushing and grinding the titanium-containing blast furnace slag, and passing it through a 200-600 mesh screen;

[0045] (3) mixing 1 kg of the screened titanium-containing blast furnace slag with 1.55-2.2 kg of an 85-98 wt% sulfuric acid solution, and adding 0.1-5 g of the modified complexing agent and 5-20 g of a surfactant, and reacting at 70-130°C for 1-6 h to obtain acidolysis slag; adding 1 kg of the acidolysis slag to 1-2 kg of deionized water, stirring and mixing, and filtering to obtain a hetero-titanium sulfate solution;

[0046] (4) adding the hetero-titanium sulfate solution to a reaction kettle, and carrying out a sealed hydrothermal reaction at 110-160°C and 0.2-1 MPa for 1-12 h, cooling the product, and filtering to obtain a filter cake, which is washed and dried to obtain the hydrothermal metatitanic acid;

[0047] (5) mixing the hydrothermal metatitanic acid with a 0.5-5 wt% NaOH solution to form a slurry, adjusting the pH to 10-14, stirring at room temperature at 400-800 r / min for 30-120 min, filtering, washing, and drying at 100-110°C for 1-3 h to obtain desulfurized metatitanic acid; and calcining the desulfurized metatitanic acid in a muffle furnace at 500-1000°C for 2-5 h, and cooling to obtain the high-purity titanium dioxide.

[0048] The application will be further described below through specific examples.

[0049] Example 1

[0050] A method for preparing high-purity titanium dioxide, comprising the following steps:

[0051] (1) adding 10 mmol of iminodiacetic acid and 4 mmol of potassium carbonate to 50 mL of tetrahydrofuran, slowly adding 3.1 mmol of trimesoyl chloride (previously dissolved in 10 mL of tetrahydrofuran) dropwise under ice bath conditions, completing the dropwise addition in 90 min, stirring the reaction under ice bath for 1 h, removing the solvent tetrahydrofuran by rotary evaporation, then extracting and separating by adding ethyl acetate, and recrystallizing the product in ethyl acetate to obtain the modified complexing agent;

[0052] (2) crushing and grinding the titanium-containing blast furnace slag, and passing it through a 500 mesh screen;

[0053] (3) mixing 1 kg of the screened titanium-containing blast furnace slag with 2.2 kg of an 85 wt% sulfuric acid solution, and adding 5 g of the modified complexing agent and 20 g of a surfactant, sodium hexadecyl benzene sulfonate, and reacting at 130°C for 1 h to obtain acidolysis slag; adding 1 kg of the acidolysis slag to 2 kg of deionized water, stirring and mixing, and filtering to obtain a hetero-titanium sulfate solution;

[0054] (4) The hetero-sulfur-containing titanyl oxide solution is added into a reaction kettle, and hydrothermal reaction is carried out at 160°C and 1MPa for 1h, and then the product is cooled and filtered to obtain a filter cake, which is washed and dried to obtain the hydrothermal metatitanic acid;

[0055] (5) The hydrothermal metatitanic acid is mixed with a 3wt% NaOH solution to prepare a slurry, and the pH is adjusted to 12, and then the slurry is stirred at room temperature and 600r / min for 90min, and then the product is filtered, washed and dried at 105°C for 2h to obtain the desulfurized metatitanic acid; the desulfurized metatitanic acid is calcined in a muffle furnace at 600°C for 4h, and then cooled to obtain the anatase high-purity titanium dioxide with a purity of 99.5%.

[0056] The SEM photo of the anatase titanium dioxide prepared in Example 1 is shown in Figure 1 .

[0057] Example 2

[0058] A preparation method of high-purity titanium dioxide, comprising the following steps:

[0059] (1) 10mmol iminodiacetic acid and 3mmol potassium carbonate are added into 50mL tetrahydrofuran, and 2.5mmol trimesoyl chloride (previously dissolved in 10mL tetrahydrofuran) is slowly added dropwise under ice bath condition, and the dropping is completed in 60min, and then the product is stirred in ice bath for 3h, and then the solvent tetrahydrofuran is removed by rotary evaporation, and then ethyl acetate is added for extraction and separation, and then the product is recrystallized in ethyl acetate to obtain the modified complexing agent;

[0060] (2) The titanium-containing blast furnace slag is crushed and ground, and then passed through a 400-mesh sieve;

[0061] (3) 1kg of the sieved titanium-containing blast furnace slag is mixed with 1.9kg of a 93wt% sulfuric acid solution, and 2.5g of the modified complexing agent and 12g of the surfactant sodium hexadecyl benzene sulfonate are added, and then the mixture is reacted at 100°C for 3h to obtain the acidolysis slag; 1kg of the acidolysis slag is added into 1.5kg of deionized water, and then the mixture is stirred and mixed, and then filtered to obtain the hetero-sulfur-containing titanyl oxide solution;

[0062] (4) The hetero-sulfur-containing titanyl oxide solution is added into a reaction kettle, and hydrothermal reaction is carried out at 130°C and 0.6MPa for 6h, and then the product is cooled and filtered to obtain a filter cake, which is washed and dried to obtain the hydrothermal metatitanic acid;

[0063] (5) The hydrothermal metatitanic acid is mixed with a 3wt% NaOH solution to prepare a slurry, and the pH is adjusted to 12, and then the slurry is stirred at room temperature and 600r / min for 90min, and then the product is filtered, washed and dried at 105°C for 2h to obtain the desulfurized metatitanic acid; the desulfurized metatitanic acid is calcined in a muffle furnace at 600°C for 4h, and then cooled to obtain the anatase high-purity titanium dioxide with a purity of 99.4%.

[0064] Example 3

[0065] A method for preparing high-purity titanium dioxide, comprising the following steps:

[0066] (1) 10 mmol of iminodiacetic acid and 2.5 mmol of potassium carbonate are added to 50 mL of tetrahydrofuran, and 2.1 mmol of trimesoyl chloride (dissolved in 10 mL of tetrahydrofuran in advance) is slowly added dropwise under ice bath conditions, and the dropwise addition is completed in 30 min, and the reaction is stirred in an ice bath for 6 h, the product is spin-evaporated to remove the solvent tetrahydrofuran, then ethyl acetate is added for extraction and separation, spin-evaporation is performed, and the product is recrystallized in ethyl acetate to obtain the modified complexing agent;

[0067] (2) The titanium-containing blast furnace slag is crushed, ground, and passed through a 400-mesh sieve;

[0068] (3) 1 kg of the sieved titanium-containing blast furnace slag is mixed with 1.55 kg of an 85wt% sulfuric acid solution, and 1 g of the modified complexing agent and 5 g of the surfactant sodium hexadecyl benzene sulfonate are added, and the mixture is reacted at 70°C for 6 h to obtain acidolysis slag; 1 kg of the acidolysis slag is added to 1 kg of deionized water, stirred and mixed, filtered, and a titanium oxysulfate solution containing impurities is obtained;

[0069] (4) The titanium oxysulfate solution containing impurities is added to a reaction kettle, and a sealed hydrothermal reaction is performed at 110°C and 0.2 MPa for 12 h, the product is cooled and filtered to obtain a filter cake, the filter cake is washed and dried to obtain hydrothermal metatitanic acid;

[0070] (5) The hydrothermal metatitanic acid is mixed with a 3wt% NaOH solution to prepare a slurry, the pH is adjusted to 12, and the slurry is stirred at room temperature at 600 r / min for 90 min, the product is filtered, washed, and dried at 105°C for 2 h to obtain desulfurized metatitanic acid; the desulfurized metatitanic acid is calcined in a muffle furnace at 500°C for 5 h, and cooled to obtain anatase-type high-purity titanium dioxide with a purity of 99.2%.

[0071] Example 4

[0072] A method for preparing high-purity titanium dioxide, comprising the following steps:

[0073] (1) 10 mmol of iminodiacetic acid and 2.5 mmol of potassium carbonate are added to 50 mL of tetrahydrofuran, and 2.1 mmol of trimesoyl chloride (dissolved in 10 mL of tetrahydrofuran in advance) is slowly added dropwise under ice bath conditions, and the dropwise addition is completed in 30 min, and the reaction is stirred in an ice bath for 6 h, the product is spin-evaporated to remove the solvent tetrahydrofuran, then ethyl acetate is added for extraction and separation, spin-evaporation is performed, and the product is recrystallized in ethyl acetate to obtain the modified complexing agent;

[0074] (2) The titanium-containing blast furnace slag is crushed, ground, and passed through a 400-mesh sieve;

[0075] (3) 1 kg of the sieved titanium-containing blast furnace slag was mixed with 1.9 kg of a 93 wt% sulfuric acid solution, and 2.5 g of a modified complexing agent, 12 g of a surfactant sodium dodecyl benzene sulfonate were added, and reacted at 100°C for 3 h to obtain acidolysis slag; 1 kg of the acidolysis slag was added to 1.5 kg of deionized water, stirred and mixed, and filtered to obtain a hetero-titanium sulfate acid solution;

[0076] (4) The hetero-titanium sulfate acid solution was added to a reaction kettle, and hydrothermal reaction was carried out at 130°C and 0.6 MPa for 6 h, and the product was cooled and filtered to obtain a filter cake, which was washed and dried to obtain hydrothermal metatitanic acid;

[0077] (5) The hydrothermal metatitanic acid was mixed with a 3 wt% NaOH solution to prepare a slurry, the pH was adjusted to 12, and the slurry was stirred at room temperature at 600 r / min for 90 min, and the product was filtered, washed, and dried at 105°C for 2 h to obtain desulfurized metatitanic acid; the desulfurized metatitanic acid was calcined in a muffle furnace at 900°C for 3 h, and cooled to obtain rutile-type high-purity titanium dioxide with a purity of 99.3%.

[0078] Comparative Example 1

[0079] A method for preparing titanium dioxide from titanium-containing blast furnace slag, comprising the following steps:

[0080] (1) The titanium-containing blast furnace slag was crushed and ground, and sieved through a 500-mesh sieve;

[0081] (2) 1 kg of the sieved titanium-containing blast furnace slag was mixed with 2.2 kg of an 85 wt% sulfuric acid solution, and 5 g of a complexing agent iminodiacetic acid, 20 g of a surfactant sodium dodecyl benzene sulfonate were added, and reacted at 130°C for 1 h to obtain acidolysis slag; 1 kg of the acidolysis slag was added to 2 kg of deionized water, stirred and mixed, and filtered to obtain a hetero-titanium sulfate acid solution;

[0082] (3) The hetero-titanium sulfate acid solution was added to a reaction kettle, and hydrothermal reaction was carried out at 160°C and 1 MPa for 1 h, and the product was cooled and filtered to obtain a filter cake, which was washed and dried to obtain hydrothermal metatitanic acid;

[0083] (4) The hydrothermal metatitanic acid was mixed with a 3 wt% NaOH solution to prepare a slurry, the pH was adjusted to 12, and the slurry was stirred at room temperature at 600 r / min for 90 min, and the product was filtered, washed, and dried at 105°C for 2 h to obtain desulfurized metatitanic acid; the desulfurized metatitanic acid was calcined in a muffle furnace at 700°C for 4 h, and cooled to obtain anatase-type titanium dioxide with a purity of 98.1%.

[0084] Comparative Example 2

[0085] A method for preparing titanium dioxide from titanium-containing blast furnace slag, comprising the following steps:

[0086] (1) The titanium-containing blast furnace slag is crushed, ground, and passed through a 500-mesh sieve;

[0087] (2) 1 kg of the sieved titanium-containing blast furnace slag is mixed with 2.2 kg of an 85wt% sulfuric acid solution, and 5 g of a complexing agent ethylenediaminetetraacetic acid, 20 g of a surfactant sodium hexadecyl benzene sulfonate are added, and the mixture is reacted at 130°C for 1 h to obtain acidolysis slag; 1 kg of the acidolysis slag is added to 2 kg of deionized water, stirred and mixed, filtered, and a hetero-titanium sulfate solution is obtained;

[0088] (3) The hetero-titanium sulfate solution is added to a reaction kettle, and a hydrothermal reaction is carried out at 160°C and 1 MPa for 1 h, the product is cooled and filtered to obtain a filter cake, the filter cake is washed and dried to obtain hydrothermal metatitanic acid;

[0089] (4) The hydrothermal metatitanic acid is mixed with a 3wt% NaOH solution to form a slurry, the pH is adjusted to 12, and the slurry is stirred at room temperature at 600 r / min for 90 min, the product is filtered, washed, and dried at 105°C for 2 h to obtain desulfurized metatitanic acid; the desulfurized metatitanic acid is calcined in a muffle furnace at 700°C for 4 h, and cooled to obtain anatase titanium dioxide with a purity of 98.2%.

[0090] Comparative Example 3

[0091] A method for preparing high-purity titanium dioxide, comprising the following steps:

[0092] (1) 10 mmol of iminodiacetic acid and 4 mmol of potassium carbonate are added to 50 mL of tetrahydrofuran, and 3.1 mmol of trimesoyl chloride is slowly added dropwise under ice bath conditions (previously dissolved in 10 mL of tetrahydrofuran), and the dropwise addition is completed in 90 min, and the product is stirred in an ice bath for 1 h, then the solvent tetrahydrofuran is removed by rotary evaporation, followed by extraction and separation with ethyl acetate, and the product is recrystallized in ethyl acetate to obtain the modified complexing agent;

[0093] (2) The titanium-containing blast furnace slag is crushed, ground, and passed through a 500-mesh sieve;

[0094] (3) 1 kg of the sieved titanium-containing blast furnace slag is mixed with 2.2 kg of an 85wt% sulfuric acid solution, and 5 g of the modified complexing agent is added, and the mixture is reacted at 130°C for 1 h to obtain acidolysis slag; 1 kg of the acidolysis slag is added to 2 kg of deionized water, stirred and mixed, filtered, and a hetero-titanium sulfate solution is obtained;

[0095] (4) The hetero-titanium sulfate solution is added to a reaction kettle, and a hydrothermal reaction is carried out at 160°C and 1 MPa for 1 h, the product is cooled and filtered to obtain a filter cake, the filter cake is washed and dried to obtain hydrothermal metatitanic acid;

[0096] (5) the metatitanic acid is mixed with 3wt% NaOH solution to prepare a slurry, the pH is adjusted to 12, the slurry is stirred at room temperature for 90 min at 600 r / min, the product is filtered, washed, and dried at 105°C for 2 h to obtain desulfurized metatitanic acid; the desulfurized metatitanic acid is calcined in a muffle furnace at 700°C for 4 h, and cooled to obtain anatase high-purity titanium dioxide with a purity of 98.9%.

[0097] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, within the technical scope disclosed by the present application, according to the technical scheme and inventive concept of the present application, makes equivalent replacements or changes, which should be encompassed in the protection scope of the present application.

Claims

1. A method for producing high-purity titanium dioxide, characterized by, It comprises the following steps: (1) crushing, grinding and sieving the titanium-containing blast furnace slag; (2) mixing the sieved titanium-containing blast furnace slag with a sulfuric acid solution, adding a modified complexing agent and a surfactant, heating and reacting to obtain acidolysis slag, adding the acidolysis slag into deionized water, stirring and mixing, filtering to obtain a mixed titanium metatitanate sulfuric acid solution; (3) adding the mixed titanium metatitanate sulfuric acid solution into a reaction kettle, sealing and hydrothermally reacting, cooling and filtering the product to obtain a filter cake, washing and drying the filter cake to obtain the hydrothermal metatitanic acid; (4) mixing the hydrothermal metatitanic acid with a NaOH solution to prepare a slurry, adjusting the pH, stirring at room temperature, filtering, washing and drying the product to obtain desulfurized metatitanic acid, and roasting and cooling the desulfurized metatitanic acid to obtain the high-purity titanium dioxide; In step (2), the modified complexing agent and the surfactant are used in an amount of 0.01-0.5wt% and 0.5-2wt% of the titanium-containing blast furnace slag, respectively. In step (2), the modified complexing agent is prepared by the following steps: adding iminodiacetic acid and potassium carbonate into tetrahydrofuran, slowly adding trimesoyl chloride dropwise under ice bath conditions, stirring and reacting under ice bath conditions, removing the solvent tetrahydrofuran from the product by rotary evaporation, then adding ethyl acetate for extraction and separation, rotary evaporation, and recrystallizing the product in ethyl acetate to obtain the modified complexing agent; The molar ratio of the iminodiacetic acid, the potassium carbonate and the trimesoyl chloride is 1:2.5-4:2-3.1; The trimesoyl chloride is added dropwise for 30-90min, and the stirring and reaction conditions are 0-5℃ and 1-6h.

2. The production method according to claim 1, characterized by, In step (1), the sieving is performed through a 200-600 mesh sieve.

3. The preparation method according to claim 1, characterized in that, In step (2), the sulfuric acid solution has a concentration of 85-98wt%, and the heating and reaction conditions are 70-130℃ and 1-6h; the surfactant is one or more of an anionic surfactant and a nonionic surfactant.

4. The method of claim 1, wherein, In step (2), the amount ratio of the titanium-containing blast furnace slag to the sulfuric acid solution is 1:1.5-2.2, and the amount ratio of the acidolysis slag to the deionized water is 1:1-2.

5. The preparation method according to claim 1, characterized in that, In step (3), the sealing and reaction conditions are 110-160℃, 0.2-1MPa and 1-12h of hydrothermal reaction.

6. The method of claim 1, wherein, In step (4), the NaOH solution has a concentration of 0.5-5wt%, and the pH is adjusted to 10-14; the stirring conditions at room temperature are 400-800r / min and 30-120min, and the drying conditions are 100-110℃ and 1-3h; the roasting conditions are 500-1000℃ in a muffle furnace for 2-5h.

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