Method for purifying high-purity electronic-grade titanium dioxide by adopting novel chelating agent and sulfuric acid method

Abstract

The invention relates to the technical field of preparation of high-purity materials, and discloses a method for purifying high-purity electronic-grade titanium dioxide by adopting a novel chelating agent through a sulfuric acid method, which comprises the following steps: S1, preparing a chelating agent solution: selecting the novel chelating agent, dissolving the novel chelating agent in a solvent, and stirring until the novel chelating agent is completely dissolved to obtain a chelating agent solution A; s2, pretreating metatitanic acid: taking a metatitanic acid material in a slurry tank after secondary water washing in sulfuric acid method production as metatitanic acid B, measuring the concentration, heating and continuously stirring to form uniform slurry; s3, carrying out complexation reaction; s4, washing and filter pressing; s5, calcining and crushing; and S6, carrying out parallel verification. The technical effects of efficiently chelating harmful metal ions and improving the product purity are achieved by adopting a complex reaction process that a novel multi-coordination chelating agent is matched with the chelating agent firstly and then the system environment is adjusted, and compared with the technical scheme that oxalic acid is used as a complexing agent in the prior art, the technical scheme has the advantages that the production cost is reduced; the problems of limited complexing ability and incomplete removal of harmful metal ions are solved.

Description

Technical Field

[0001] This invention relates to the field of high-purity material preparation technology, specifically a method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process. Background Technology

[0002] High-purity electronic-grade titanium dioxide, primarily composed of high-purity titanium dioxide, is a core material in emerging electronic components and new energy fields. Its superior semiconductor, electromagnetic, and photocatalytic properties make it irreplaceable in applications such as thermistors, wafer capacitors, ceramic capacitors, and lithium iron phosphate cathode materials. Furthermore, its composite compounds with elements like barium, strontium, bismuth, and calcium are crucial raw materials for high-precision electronic devices such as multilayer ceramic capacitors and PTC thermistors. The purity and impurity content of these products directly determine the electrical performance, breakdown resistance, and lifespan of downstream electronic components.

[0003] Currently, the mainstream industrial method for producing high-purity electronic-grade titanium dioxide is the sulfuric acid process. The core process involves dissolving ilmenite in concentrated sulfuric acid to generate titanium oxysulfate, followed by steps such as water washing, bleaching, complexation reaction, washing and filtration, calcination and pulverization to obtain the finished product. Because ilmenite raw materials naturally contain impurities such as iron, magnesium, chromium, and manganese oxides, these impurities will form soluble salts after acid hydrolysis. These salts will enter subsequent processes along with titanium oxysulfate and need to be separated and removed by generating soluble chelates through complexation reactions. Oxalic acid is commonly used as a complexing agent in existing technologies. However, oxalic acid molecules contain only two carboxyl groups, resulting in a single coordination mode and limited complexing ability. This makes it difficult to efficiently chelate various harmful metal ions in raw materials, leading to the inability to completely remove some impurities. Ultimately, this affects the purity of high-purity electronic-grade titanium dioxide products, thereby restricting the improvement of the performance of downstream electronic components. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent via sulfuric acid. This method solves the problems of limited chelating ability and incomplete removal of harmful metal ions caused by the use of oxalic acid as a chelating agent in existing technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process, comprising the following steps: S1. Preparation of chelating agent solution: Select a novel chelating agent, dissolve it in a solvent, and stir until completely dissolved to obtain chelating agent solution A; S2. Pretreatment of metatitanic acid: Take the metatitanic acid material in the slurry tank after secondary water washing in the sulfuric acid process as metatitanic acid B. After measuring the concentration, heat and continuously stir to form a uniform slurry. S3. Perform a complexation reaction: Add the chelating agent solution A prepared in S1 to the pretreated metatitanic acid slurry B, then add deionized water and concentrated sulfuric acid, stir evenly, raise the temperature to the set temperature and keep it warm to generate slurry C. S4. Washing and filtration: After preheating the demineralized water, the slurry C obtained in S3 is filtered and washed according to the set washing water ratio. After solid-liquid separation, material D is obtained. S5. Calcination and pulverization: The material D obtained in S4 is placed in a calcination device, heated from room temperature to the set calcination temperature, and immediately taken out and pulverized using a grinding device to obtain a high-purity electronic-grade titanium dioxide sample E. S6. Parallel verification: Change to a new type of chelating agent, repeat S1-S5, and conduct multiple sets of parallel purification experiments.

[0006] Preferably, in step S1, the novel chelating agent is selected from any one of tannic acid, citric acid, tartaric acid, and organic complexing agent LR04, with a dosage of 10-15g, the solvent being desalinated water, the concentration of chelating agent solution A being 200-300g / L, and the volume being 40-60mL.

[0007] Preferably, in step S2, the amount of metatitanic acid B used is 80-120 mL, the concentration is 320-360 g / L, the heating temperature is 45-55℃, the stirring rate is 100-300 r / min, and the stirring time is 10-20 min.

[0008] Preferably, in step S3, the amount of concentrated sulfuric acid added is 0.5-2% of the mass of the metatitanic acid slurry B, the dropping rate is 1-5 mL / min, the reaction temperature after heating is 65-75℃, and the holding time is 0.8-1.2 h.

[0009] Preferably, in step S4, the preheating temperature of the demineralized water is 45-55℃, the washing water ratio is 4-6 times the volume of slurry C, and the vacuum degree of the filtration washing is 0.06-0.09MPa.

[0010] Preferably, in step S4, the number of washes is 3-5 times, and the washing time for each wash is 10-20 minutes.

[0011] Preferably, in step S5, the calcination equipment is a muffle furnace, the material D is placed in the center of the muffle furnace, the heating rate of the muffle furnace is 10-20℃ / min, and the calcination temperature is set to 900-940℃.

[0012] Preferably, in step S5, the grinding equipment is a three-head grinder, the grinding time is 5-15 min, and the particle size of sample E is 1-5 μm.

[0013] Preferably, in step S1, when preparing the chelating agent solution A, the temperature during the dissolution process is controlled at 25-40°C, and mechanical stirring is used with a stirring rate of 150-250 r / min and a stirring time of 15-30 min.

[0014] Preferably, in step S3, after adding demineralized water and concentrated sulfuric acid to adjust the system, the solid-liquid volume ratio of the slurry needs to be controlled to be 1:2-1:4, and the heating process adopts a gradient heating method, raising the temperature from room temperature to the set reaction temperature at a rate of 5-10℃ / min, while continuously stirring during the heat preservation period.

[0015] This invention provides a novel chelating agent for the purification of high-purity electronic-grade titanium dioxide using a sulfuric acid process. It offers the following advantages: 1. This invention achieves the technical effect of highly efficient chelation of harmful metal ions and improved product purity by using a novel multi-coordination chelating agent combined with a complexation reaction process that first adds the chelating agent and then adjusts the system environment. Compared with the existing technology that uses oxalic acid as a complexing agent, this invention solves the problems of limited complexing ability and incomplete removal of harmful metal ions.

[0016] 2. The present invention adopts a synergistic process design that combines gradient heating, heat preservation reaction with vacuum filtration and washing, and timely washing after complexation. This achieves the technical effect of ensuring uniform and sufficient complexation reaction and avoiding secondary residue of impurities. Compared with the existing technology of directly heating, omitting heat preservation or delaying washing, it solves the problems of uneven local reaction and impurity adsorption and reflux caused by complex dissociation.

[0017] 3. The present invention adopts an integrated technical solution with precise parameter matching for each process step, including chelating agent solution preparation, metatitanic acid pretreatment, complexation reaction, washing, filtration and calcination. This achieves stable product performance and adaptability to different production scenarios. Compared with the existing technology, which has disconnected process links and unreasonable parameter settings, this invention solves the problems of large product quality fluctuations, limited applicability and high production costs. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to the present invention; Figure 2 This is a schematic diagram comparing the purification effects of different chelating agents in the sulfuric acid method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent, as described in this invention. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see the appendix Figure 1 - Appendix Figure 2 This invention provides a method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid method, comprising the following steps: S1. Preparation of chelating agent solution: Select a novel chelating agent, dissolve it in a solvent, and stir until completely dissolved to obtain chelating agent solution A; In S1, the novel chelating agent is selected from any one of tannic acid, citric acid, tartaric acid, and organic complexing agent LR04, with a dosage of 10-15g, the solvent being desalinated water, and the concentration of chelating agent solution A being 200-300g / L and the volume being 40-60mL. In S1, when preparing chelating agent solution A, the temperature during the dissolution process is controlled at 25-40℃, and mechanical stirring is used with a stirring rate of 150-250 r / min and a stirring time of 15-30 min. S2. Pretreatment of metatitanic acid: Take the metatitanic acid material in the slurry tank after secondary water washing in the sulfuric acid process as metatitanic acid B. After measuring the concentration, heat and continuously stir to form a uniform slurry. In S2, the amount of metatitanic acid B used is 80-120 mL, the concentration is 320-360 g / L, the heating temperature is 45-55℃, the stirring rate is 100-300 r / min, and the stirring time is 10-20 min. S3. Perform a complexation reaction: Add the chelating agent solution A prepared in S1 to the pretreated metatitanic acid slurry B, then add deionized water and concentrated sulfuric acid, stir evenly, raise the temperature to the set temperature and keep it warm to generate slurry C. In S3, the amount of concentrated sulfuric acid added is 0.5-2% of the mass of metatitanic acid slurry B, the dropping rate is 1-5 mL / min, the reaction temperature after heating is 65-75℃, and the holding time is 0.8-1.2 h. In S3, after adding demineralized water and concentrated sulfuric acid to adjust the system, the solid-liquid volume ratio of the slurry needs to be controlled at 1:2-1:4, and the heating process adopts a gradient heating method, raising the temperature from room temperature to the set reaction temperature at a rate of 5-10℃ / min, and stirring continuously during the heat preservation period. S4. Washing and filtration: After preheating the demineralized water, the slurry C obtained in S3 is filtered and washed according to the set washing water ratio. After solid-liquid separation, material D is obtained. In S4, the preheating temperature of the demineralized water is 45-55℃, the washing water ratio is 4-6 times the volume of slurry C, and the vacuum degree of the filtration washing is 0.06-0.09MPa. In S4, the number of washes is 3-5 times, and the washing time for each wash is 10-20 minutes; S5. Calcination and pulverization: The material D obtained in S4 is placed in a calcination device, heated from room temperature to the set calcination temperature, and immediately taken out and pulverized using a grinding device to obtain a high-purity electronic-grade titanium dioxide sample E. In S5, the calcination equipment is a muffle furnace, the material D is placed in the center of the muffle furnace, the heating rate of the muffle furnace is 10-20℃ / min, and the calcination temperature is set to 900-940℃. In S5, the grinding equipment is a three-head grinder, the grinding time is 5-15 min, and the particle size of sample E is 1-5 μm; S6. Parallel verification: Change to a new type of chelating agent, repeat S1-S5, and conduct multiple sets of parallel purification experiments.

[0021] The following is a description with reference to specific embodiments: Example 1: A method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process, comprising the following steps: S1. Preparation of chelating agent solution: Citric acid is selected as a new chelating agent. Weigh 10g of citric acid and add 40mL of desalinated water as solvent. Control the dissolution temperature at 25℃. Use mechanical stirring and set the stirring speed to 150r / min. Continue stirring for 15min until the citric acid is completely dissolved to form a chelating agent solution A that is free of precipitate, homogeneous and stable, with a concentration of 200g / L. S2. Pretreatment of metatitanic acid: Take the metatitanic acid material in the slurry tank after secondary water washing in the sulfuric acid process as metatitanic acid B, and take 80 mL. Determine its concentration as 320 g / L by specific gravity measurement. Heat it to 45℃, set the stirring speed to 100 r / min, and stir continuously for 10 min to form a uniformly dispersed metatitanic acid slurry. S3. Complexation reaction: Slowly add the chelating agent solution A prepared in S1 to the pretreated metatitanic acid slurry B, followed by deionized water and concentrated sulfuric acid, with the amount added being 0.5% of the mass of metatitanic acid slurry B. Control the dropping rate of concentrated sulfuric acid at 1 mL / min, adjust the solid-liquid volume ratio of the system to 1:2, stir evenly, and then use a gradient heating method to raise the temperature from room temperature to 65℃ at a rate of 5℃ / min. During the heat preservation period, maintain the stirring rate at 100 r / min and continue the heat preservation reaction for 0.8 h to generate slurry C. S4. Washing and filtration: Preheat the demineralized water to 45°C, and wash the slurry C with a washing water ratio of 4 times the volume of slurry C under a vacuum of 0.06 MPa for a total of 3 washes, each wash lasting 10 minutes. Soluble metal chelates are removed by solid-liquid separation to obtain material D. S5. Calcination and pulverization: Place material D in the center of the muffle furnace, set the heating rate of the muffle furnace to 10℃ / min, and take out the material immediately after heating from room temperature to 900℃. Put the material into a three-head grinder and pulverize for 5 minutes to obtain high-purity electronic-grade titanium dioxide sample E with a particle size of 1-3μm. S6. Parallel verification: Replace the new chelating agent with tannic acid, tartaric acid, and organic complexing agent LR04 respectively, repeat the above steps S1-S5, keep each parameter at its corresponding minimum value, conduct multiple sets of parallel purification experiments, and detect the indicators of each set of samples.

[0022] Example 2: A method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process, comprising the following steps: S1. Preparation of chelating agent solution: Citric acid is selected as a new chelating agent. Weigh 12.5g of citric acid and add 50mL of deionized water as solvent. Control the dissolution temperature at 30℃. Use mechanical stirring and set the stirring speed to 200r / min. Continue stirring for 20min until the citric acid is completely dissolved to form a chelating agent solution A that is free of precipitate, homogeneous and stable, with a concentration of 250g / L. S2. Pretreatment of metatitanic acid: Take the metatitanic acid material in the slurry tank after secondary water washing in the sulfuric acid process as metatitanic acid B. Take 100 mL and determine its concentration as 340 g / L by specific gravity measurement. Heat it to 50℃, set the stirring speed to 200 r / min, and stir continuously for 15 min to form a uniformly dispersed metatitanic acid slurry. S3. Complexation reaction: Slowly add the chelating agent solution A prepared in S1 to the pretreated metatitanic acid slurry B, followed by deionized water and concentrated sulfuric acid. The amount added is 1% of the mass of metatitanic acid slurry B. Control the dropping rate of concentrated sulfuric acid at 3 mL / min and adjust the solid-liquid volume ratio of the system to 1:3. After stirring evenly, use a gradient heating method to raise the temperature from room temperature to 70℃ at a rate of 7℃ / min. During the heat preservation period, maintain the stirring rate at 200 r / min and continue the heat preservation reaction for 1 h to generate slurry C. S4. Washing and filtration: Preheat the demineralized water to 50°C, and wash the slurry C with a washing water ratio of 5 times the volume of slurry C under a vacuum of 0.08 MPa for a total of 4 washes, each wash lasting 15 minutes. Soluble metal chelates are removed by solid-liquid separation to obtain material D. S5. Calcination and pulverization: Place material D in the center of the muffle furnace, set the heating rate of the muffle furnace to 15℃ / min, and take out the material immediately after heating from room temperature to 920℃. Put the material into a three-head grinder and pulverize for 10 minutes to obtain high-purity electronic-grade titanium dioxide sample E with a particle size of 2-4μm. S6. Parallel verification: Replace the new chelating agent with tannic acid, tartaric acid, and organic complexing agent LR04 respectively, repeat the above steps S1-S5, keep each parameter at its corresponding optimal value, conduct multiple sets of parallel purification experiments, and detect the indicators of each group of samples.

[0023] Example 3: A method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process, comprising the following steps: S1. Preparation of chelating agent solution: Citric acid is selected as a new chelating agent. Weigh 15g of citric acid and add 60mL of desalinated water as solvent. Control the dissolution temperature at 40℃. Use mechanical stirring and set the stirring speed to 250r / min. Continue stirring for 30min until the citric acid is completely dissolved to form a chelating agent solution A that is free of precipitate, homogeneous and stable, with a concentration of 300g / L. S2. Pretreatment of metatitanic acid: Take the metatitanic acid material in the slurry tank after secondary water washing in the sulfuric acid process as metatitanic acid B. Take 120 mL and determine its concentration as 360 g / L by specific gravity measurement. Heat it to 55℃, set the stirring speed to 300 r / min, and stir continuously for 20 min to form a uniformly dispersed metatitanic acid slurry. S3. Complexation reaction: Slowly add the chelating agent solution A prepared in S1 to the pretreated metatitanic acid slurry B, followed by deionized water and concentrated sulfuric acid, the amount of which is 2% of the mass of metatitanic acid slurry B. Control the dropping rate of concentrated sulfuric acid at 5 mL / min, adjust the solid-liquid volume ratio of the system to 1:4, stir evenly, and then use a gradient heating method to raise the temperature from room temperature to 75℃ at a rate of 10℃ / min. During the heat preservation period, maintain the stirring rate at 300 r / min and continue the heat preservation reaction for 1.2 h to generate slurry C. S4. Washing and filtration: Preheat the demineralized water to 55°C, and wash the slurry C with a washing water ratio of 6 times the volume of slurry C under a vacuum of 0.09 MPa for a total of 5 washes, each wash lasting 20 minutes. Soluble metal chelates are removed by solid-liquid separation to obtain material D. S5. Calcination and pulverization: Place material D in the center of the muffle furnace, set the heating rate of the muffle furnace to 20℃ / min, and take out the material immediately after heating from room temperature to 940℃. Put the material into a three-head grinder and pulverize for 15min to obtain high-purity electronic-grade titanium dioxide sample E with a particle size of 3-5μm. S6. Parallel verification: Replace the new chelating agent with tannic acid, tartaric acid, and organic complexing agent LR04 respectively, repeat the above steps S1-S5, keep all parameters at their corresponding maximum values, conduct multiple sets of parallel purification experiments, and detect the indicators of each group of samples.

[0024] Comparative Example 1: Unlike Example 2, when performing the complexation reaction in S3, deionized water and concentrated sulfuric acid were first added to the metatitanic acid slurry B pretreated by S2, and then the chelating agent solution A prepared in S1 was added. All other process parameters were the same as in Example 2.

[0025] Comparative Example 2: Unlike Example 2, when S3 carried out the complexation reaction, the temperature was directly raised to 70°C after stirring evenly, without using a gradient heating method. All other process parameters were the same as in Example 2.

[0026] Comparative Example 3: Unlike Example 2, when S3 carried out the complexation reaction, the heating was stopped immediately after the temperature was raised to 70°C, and no heat preservation reaction was carried out. All other process parameters were the same as those in Example 2.

[0027] Comparative Example 4: Unlike Example 2, atmospheric pressure filtration was used instead of vacuum filtration during the S4 washing and pressure filtration process, and the vacuum degree was not controlled. All other process parameters were the same as in Example 2.

[0028] Comparative Example 5: Unlike Example 2, after slurry C is generated in S3, it is first placed at room temperature for 30 minutes before washing and filtration in S4. All other process parameters are the same as in Example 2.

[0029] Comparative Example 1: Unlike Example 2, oxalic acid was replaced with tannic acid as the chelating agent. Other experimental steps and conditions remained unchanged. The calcined samples were ground and pulverized, and the corresponding indicators were tested for comparative analysis. All other process parameters were the same as in Example 2.

[0030] Comparative Example 2: Unlike Example 2, oxalic acid was replaced with citric acid as the chelating agent. Other experimental steps and conditions remained unchanged. The calcined samples were ground and pulverized, and the corresponding indicators were tested for comparative analysis. All other process parameters were the same as in Example 2.

[0031] Comparative Example 3: Unlike Example 2, oxalic acid was replaced with tartaric acid as the chelating agent. Other experimental steps and conditions remained unchanged. The calcined samples were ground and pulverized, and the corresponding indicators were tested for comparative analysis. All other process parameters were the same as in Example 2.

[0032] Comparative Example 4: Unlike Example 2, oxalic acid was replaced with the organic reducing agent LRO4 as a chelating agent. Other experimental steps and conditions remained unchanged. The calcined small samples were ground and pulverized, and the corresponding indicators were tested for comparative analysis. All other process parameters were the same as in Example 2.

[0033] Table 1, Performance Test Data Table Combined with Examples 1-3, Comparative Examples 1-4, performance test data table, and comparison table of purification effects of different chelating agents. Figure 2 It is evident that the screening and selection of novel multi-coordination chelating agents, the synergistic feeding sequence of core process steps, gradient heating, heat preservation reaction, vacuum filtration and washing, and precise adaptation of parameters in each step are three key factors that significantly affect the iron content, titanium dioxide purity, and particle size stability of high-purity electronic-grade titanium dioxide. Furthermore, there is a synergistic effect among these factors, namely, efficient complexation of harmful metal ions, prevention of complex dissociation, and thorough separation of impurities. Among these factors, the optimization of the type of chelating agent is the core prerequisite for improving the purification effect, and process synergy is the key support for ensuring stable performance.

[0034] Comparative examples of chelating agent replacements and Figure 2 Data shows that oxalic acid chelating agents commonly used in existing technologies have limited complexing ability due to containing only two carboxyl groups and a single coordination mode. Iron content is as high as 38.83 ppm, and titanium dioxide purity is only 99.491%. In contrast, the novel chelating agents selected in this invention, such as tannic acid, citric acid, tartaric acid, and the organic complexing agent LR04, significantly improve complexing ability due to the structural advantages of multiple carboxyl and hydroxyl groups. When citric acid is used as a chelating agent, the iron content is as low as 16.14 ppm, and the titanium dioxide purity reaches 99.787%, achieving the best purification effect. The organic complexing agents LR04, tannic acid, and tartaric acid are also superior to oxalic acid, reducing iron content to 18.84 ppm, 29.83 ppm, and 31.64 ppm respectively, with purity all exceeding 99.55%. In contrast, in the comparative examples of chelating agent replacement, only the chelating agent was replaced without changing other processes, and the significant advantages of the new chelating agent in impurity removal were still demonstrated. This confirms the necessity of using the new chelating agent in this invention and solves the core problems of insufficient complexing ability of traditional oxalic acid and incomplete removal of harmful metal ions.

[0035] Comparative Example 1 changed the feeding order, adding concentrated sulfuric acid first and then the chelating agent. The sudden increase in system acidity disrupted the coordination structure of the chelating agent, causing the iron content to rise to 28.56 ppm, an increase of 12.42 ppm compared to Example 2, and the purity to drop to 99.532%, indicating insufficient complexation reaction. Comparative Example 2 eliminated the gradient heating and directly increased the temperature, resulting in uneven local reactions. The iron content was 24.31 ppm, and the purity was 99.615%, with some harmful metal ions not completely complexed. Comparative Example 3 omitted the heat preservation reaction, resulting in insufficient complexation time. The iron content was as high as 32.78 ppm, and the purity was 99.486%, indicating that the chelating agent did not fully combine with impurities. Comparative Example 4 used atmospheric pressure filtration instead of vacuum filtration, resulting in insufficient solid-liquid separation efficiency. The iron content was 26.93 ppm, and the purity was 99.578%, with some soluble complexes not completely removed. The above data show that the absence or unreasonable adjustment of a single process step can disrupt the synergistic logic of chelating agent complexation, uniform reaction, and efficient separation, confirming the rationality of the process step design of this invention.

[0036] Examples 1-3, using citric acid as the core chelating agent, all achieved excellent results with iron content ≤20ppm and titanium dioxide purity ≥99.7%. Example 2 combined with… Figure 2 The optimal purification effect of citric acid, combined with parameters such as a chelating agent concentration of 250 g / L, a complexation temperature of 70℃, and a holding time of 1 h, resulted in an iron content of 16.14 ppm and a purity of 99.787%, exhibiting the best overall performance. Example 1, with its minimum parameters meeting the needs of low-cost, large-scale production, achieved an iron content of 19.80 ppm and a purity of 99.700%, still significantly superior to all comparative examples. Example 3, with its maximum parameters, met the requirements for high-purity electronic component raw materials, achieving an iron content of 17.32 ppm and a purity of 99.765%, with stable product quality. The excellent performance of these three examples verifies the rationality of the parameter range settings in this invention. Each parameter is precisely matched to the impurity content of metatitanic acid, the complexation reaction law, and the impurity separation efficiency, flexibly meeting the needs of different production scenarios.

[0037] This invention solves the core problems of insufficient oxalic acid complexing ability and incomplete removal of harmful metal ions in the traditional sulfuric acid process by integrating screening of novel multi-coordination chelating agents, synergistic use of key processes and parameter adaptation. Furthermore, it avoids problems such as uneven local reaction, dissociation of complexes and residual impurities by standardizing the feeding sequence, gradient heating, heat preservation reaction, and vacuum filtration and washing processes.

[0038] Example 2 achieves the optimal balance between performance and cost-effectiveness; the purification effect of citric acid as the core chelating agent is demonstrated by… Figure 2 The data validated the optimality; Examples 1-3 cover the parameter gradient range and are adapted to different production needs; the two comparative examples, from the aspects of process and chelating agent, indirectly confirmed the innovation and rationality of the technical solution of this invention.

[0039] In summary, this invention significantly improves the purity and performance stability of high-purity electronic-grade titanium dioxide. The preparation process is simple and easy to scale up, and it is fully adaptable to production scenarios with different impurity contents and different purity requirements. It provides a replicable and highly reliable technical solution for the fine purification of electronic-grade titanium dioxide, effectively supporting the performance upgrade of downstream electronic components, new energy cathode materials and other fields.

[0040] Table 2, GB Testing Standards Iron content (ppm): The sample was completely dissolved by microwave digestion. The intensity of the characteristic spectral lines of iron was determined by inductively coupled plasma mass spectrometry. The iron content was calculated by the standard curve method. The detection limit was ≤0.1ppm. Titanium dioxide purity (%): The sample was dissolved in sulfuric acid and hydrofluoric acid, titanium ions were reduced to trivalent by aluminum foil, and titrated with potassium dichromate standard solution under carbon dioxide protection. The titanium dioxide content was calculated based on the volume consumed. Particle size (μm): The sample is uniformly dispersed in demineralized water and injected into the sample cell of a laser particle size analyzer. The particle size distribution is detected by laser scattering signal, and the main distribution range is taken as the detection result.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process, characterized in that, Includes the following steps: S1. Preparation of chelating agent solution: Select a novel chelating agent, dissolve it in a solvent, and stir until completely dissolved to obtain chelating agent solution A; S2. Pretreatment of metatitanic acid: Take the metatitanic acid material in the slurry tank after secondary water washing in the sulfuric acid process as metatitanic acid B. After measuring the concentration, heat and continuously stir to form a uniform slurry. S3. Perform a complexation reaction: Add the chelating agent solution A prepared in S1 to the pretreated metatitanic acid slurry B, then add deionized water and concentrated sulfuric acid, stir evenly, raise the temperature to the set temperature and keep it warm to generate slurry C. S4. Washing and filtration: After preheating the demineralized water, the slurry C obtained in S3 is filtered and washed according to the set washing water ratio. After solid-liquid separation, material D is obtained. S5. Calcination and pulverization: The material D obtained in S4 is placed in a calcination device, heated from room temperature to the set calcination temperature, and immediately taken out and pulverized using a grinding device to obtain a high-purity electronic-grade titanium dioxide sample E. S6. Parallel verification: Change to a new type of chelating agent, repeat S1-S5, and conduct multiple sets of parallel purification experiments.

2. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In S1, the novel chelating agent is selected from any one of tannic acid, citric acid, tartaric acid, and organic complexing agent LR04, with a dosage of 10-15g, the solvent being demineralized water, and the concentration of chelating agent solution A being 200-300g / L and the volume being 40-60mL.

3. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In S2, the amount of metatitanic acid B used is 80-120 mL, the concentration is 320-360 g / L, the heating temperature is 45-55℃, the stirring rate is 100-300 r / min, and the stirring time is 10-20 min.

4. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In step S3, the amount of concentrated sulfuric acid added is 0.5-2% of the mass of the metatitanic acid slurry B, the dropping rate is 1-5 mL / min, the reaction temperature after heating is 65-75℃, and the holding time is 0.8-1.2 h.

5. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In step S4, the preheating temperature of the demineralized water is 45-55℃, the washing water ratio is 4-6 times the volume of slurry C, and the vacuum degree of the filtration washing is 0.06-0.09MPa.

6. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In step S4, the number of washes is 3-5 times, and the washing time for each wash is 10-20 minutes.

7. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In S5, the calcination equipment is a muffle furnace, the material D is placed in the center of the muffle furnace, the heating rate of the muffle furnace is 10-20℃ / min, and the calcination temperature is set to 900-940℃.

8. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In S5, the grinding equipment is a three-head grinder, the grinding time is 5-15 min, and the particle size of sample E is 1-5 μm.

9. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In step S1, when preparing chelating agent solution A, the temperature during the dissolution process is controlled at 25-40℃, and mechanical stirring is used with a stirring rate of 150-250 r / min and a stirring time of 15-30 min.

10. The method for purifying high-purity electronic-grade titanium dioxide using a novel chelating agent and sulfuric acid process according to claim 1, characterized in that: In step S3, after adding demineralized water and concentrated sulfuric acid to adjust the system, the solid-liquid volume ratio of the slurry needs to be controlled at 1:2-1:4, and the heating process adopts a gradient heating method, raising the temperature from room temperature to the set reaction temperature at a rate of 5-10℃ / min, while continuously stirring during the heat preservation period.

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