Sulfuric acid process titanium dioxide deep recycling method based on reactive distillation coupling device
By carrying out acidolysis and staged condensation in a reactive distillation column, combined with countercurrent contact and resource recovery treatment, the problems of high energy consumption and serious pollution in the traditional sulfuric acid process titanium dioxide production have been solved, realizing efficient resource recycling and low energy consumption sulfuric acid process titanium dioxide production.
Patent Information
- Application Number
- CN202511648380.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-12
- Publication Date
- 2026-02-27
AI Technical Summary
Traditional sulfuric acid process titanium dioxide production suffers from low energy efficiency, incomplete resource recovery, and serious environmental pollution. Existing technological upgrades have failed to fundamentally solve the efficiency, energy consumption, and environmental protection issues in the process.
A reactive distillation coupling device is used to mix ilmenite powder with concentrated sulfuric acid and carry out acidolysis reaction in a reactive distillation column. Combined with countercurrent contact, staged condensation and resource recovery treatment, the efficient utilization of reaction heat and closed-loop recycling of waste are achieved.
It achieves efficient recycling of sulfur, reduces wastewater by more than 80%, and lowers overall energy consumption by more than 40%, laying the foundation for the production of high-purity titanium dioxide and solving the problems of high energy consumption and pollution in traditional processes.
Smart Images
Figure FT_1 
Figure FT_2
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of chemical engineering and inorganic chemical industry, and particularly relates to a deep resource utilization method for titanium dioxide by sulfuric acid method based on a reaction distillation coupling device. BACKGROUND
[0002] The sulfuric acid method is a traditional method for preparing titanium dioxide, which uses sulfuric acid to decompose ilmenite powder or titanium slag, and then obtains titanium dioxide product through purification, hydrolysis and calcination. The traditional sulfuric acid method for producing titanium dioxide will cause a large amount of waste to be discharged, and a large amount of waste dilute sulfuric acid, ferrous sulfate heptahydrate and a large amount of waste slag will be generated. The ferrous sulfate heptahydrate is easy to weather and lose, causing serious water pollution.
[0003] The traditional method for preparing titanium dioxide is carried out in a closed reaction kettle. The influence of chemical equilibrium on the reaction leads to incomplete reaction. In addition, the traditional method for preparing titanium dioxide by the sulfuric acid method needs to go through a concentration and evaporation process after acidolysis to reach the concentration of hydrolysis, which is complex in operation and high in energy consumption.
[0004] At present, the existing technical transformation is mainly focused on local optimization, such as crystallization method, waste acid concentration, etc. However, it fails to fundamentally change the engineering nature of reaction and separation, and lacks a systematic solution that can simultaneously solve the problems of efficiency, energy consumption and environmental protection. SUMMARY
[0005] In view of the problems of low energy efficiency and incomplete resource recovery in the existing preparation method of titanium dioxide by sulfuric acid method, the application discloses a deep resource utilization method for titanium dioxide by sulfuric acid method based on a reaction distillation coupling device.
[0006] In order to solve the above problems, the application adopts the following technical scheme: A deep resource utilization method for titanium dioxide by sulfuric acid method based on a reaction distillation coupling device, comprising the following steps: S1. Reaction distillation coupling acidolysis and concentration After the ilmenite powder is mixed with 92%-98% concentrated sulfuric acid, it is sent into a reaction distillation column. The reaction distillation column provides the heat required for acidolysis, and the acidolysis reaction is carried out at a maintained operating temperature. The water produced and a small amount of decomposed SO3 gas generated in the acidolysis reaction move upward, and the upward moving steam is in countercurrent contact with the downward moving liquid material; The mixed steam discharged from the top is first condensed by a condenser, and then part of the recovered concentrated sulfuric acid is sent back into the tower through a reflux distributor. The sulfuric acid impurities in the steam are efficiently intercepted, and high-purity water vapor is removed from the top of the tower. A water-free or low-moisture titanium salt and sulfate melt is obtained at the bottom of the tower. S2. Leaching of the melt and preparation of titanium liquid The melt discharged from the reactive distillation column is directly injected into water for quenching leaching, directly obtaining high-concentration titanium liquid; S3. Fractional condensation and resource utilization of overhead vapor The high-purity water vapor discharged from the column top is subjected to fractional condensation; Primary condensation: high-temperature section condensation recovers concentrated sulfuric acid; Secondary condensation: dilute sulfuric acid obtained by low-temperature section condensation; Non-condensable gas: sent into a traditional titanium dioxide main production line, and converted into sulfuric acid by a one-turn-one-absorption or two-turn-two-absorption acid production system, and returned to the acidolysis procedure in S1 to realize sulfur closed loop; S4. Post-treatment of titanium liquid and preparation of by-products The obtained high-concentration titanium liquid meets the concentration requirement of hydrolysis after reduction and purification, and titanium dioxide product is obtained after hydrolysis, washing and calcination; ferrous sulfate produced by crystallization is directly prepared into ferrous sulfate monohydrate by using vacuum low-degree crystallization technology; S5. Directional conversion of whole-process waste by-products Titanium slag: the dilute sulfuric acid produced in S3 is mixed with the titanium slag to prepare a titanium-rich material; Acidic wastewater: after the acidic wastewater is collected, the diffusion dialysis-electrodialysis coupled membrane technology is used to recover sulfuric acid and return to the rectifying column for reuse, and the purified water is reused, so that the acidic wastewater is nearly zero discharged.
[0007] Further, the column body of the reactive distillation column in S1 is made of strong acid-resistant and high-temperature-resistant material.
[0008] Further, the operating temperature in S1 is 150-200℃.
[0009] Further, the reactive distillation column in S1 is a composite column integrating reaction, evaporation, rectification and heat exchange.
[0010] Further, the reactive distillation column in S1 is divided into a stripping section, a reactive distillation section and a rectification section from top to bottom.
[0011] Further, the reactive distillation section is provided with a column plate side line, and the reactive distillation section is filled with high-efficiency regular fillers.
[0012] Further, the rectification section is filled with high-efficiency regular fillers.
[0013] Further, the quenching leaching in S2 is rapidly reduced to 20-15℃.
[0014] Further, the concentration of titanium dioxide in the high-concentration titanium liquid in S2 is >200g / L.
[0015] Compared with the prior art, the present application has the following advantages: The application integrates the traditional four processes of acidolysis, leaching, precipitation and concentration in the reaction rectifying column, sharply reduces the number of devices and the floor area, efficiently utilizes the reaction heat, removes the concentration process, and is expected to reduce the overall energy consumption by more than 40% compared with the traditional process.
[0016] The application revolutionizes the traditional sulfuric acid method titanium dioxide process by introducing the reaction rectification process intensification technology, and realizes the fundamental change from long process, high energy consumption and high pollution to short process, low energy consumption and resource utilization.
[0017] The application enables efficient circulation of sulfur elements in the system, with a sulfur utilization rate of more than 99%, and reduces the amount of wastewater by more than 80%, solving the problems of waste acid and acidic wastewater from the source, and the fast high-temperature reaction and short process reduce the side reactions, which is beneficial to obtain purer titanium liquid and lay the foundation for producing high-grade titanium dioxide products. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 It is a process flow diagram of a sulfuric acid method titanium dioxide deep resource utilization method based on a reaction rectification coupling device.
[0019] Figure 2 It is a structural diagram of the reaction rectifying column.
[0020] In the above drawings, the reference signs are as follows: 1. Condenser, 2. Reflux distributor, 3. High-purity water vapor outlet, 4. Sulfuric acid inlet, 5. Tray side line, 6. Titanium salt melt outlet, 7. First pipeline. DETAILED DESCRIPTION
[0021] The application will be further described below in conjunction with examples. The examples are only used to illustrate the application, and are not intended to limit the application in any way.
[0022] It should be clear that the described examples are only part of the embodiments of the present application, not all. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0023] The application will be described in detail below. Figure 1
[0024] A sulfuric acid method titanium dioxide deep resource utilization method based on a reaction rectification coupling device, comprising the following steps: S1. Reaction rectification coupling acidolysis and concentration Ilmenite powder is premixed with 92%-98% concentrated sulfuric acid and fed into a reactive distillation column from the top. The column body is constructed of materials resistant to strong acids and high temperatures. The reboiler of the reactive distillation column receives energy for the reaction and separation via high-temperature heat transfer oil or high-pressure steam. The acidolysis reaction is carried out at a maintained operating temperature (150-200℃). The water and a small amount of decomposed SO3 gas produced by the acidolysis reaction rise upwards, and the upward-moving steam comes into countercurrent contact with the downward-moving liquid. The mixed steam discharged from the top of the column is first condensed by condenser 1, and then partially recovered concentrated sulfuric acid is sent back into the column through reflux distributor 2, thus coupling the reaction and separation processes and breaking down the... The reversible reaction equilibrium drives the irreversible reaction to the right, greatly improving the acidolysis rate and reaction rate. Through this process, sulfuric acid impurities in the steam are efficiently retained, and high-purity water vapor is finally removed from the top of the column. Through the bottom titanium salt melt outlet 6 at the bottom of the distillation column, anhydrous or low-moisture titanium salt and sulfate melt is continuously or intermittently discharged. S2. Melt leaching and preparation of titanium liquid The molten material discharged from the reactive distillation column is directly injected into water for rapid leaching. Since the water content in the obtained molten material is extremely low, the subsequent leaching water consumption is reduced by more than 60%, eliminating the need for the massive concentration and evaporation process, and directly obtaining a high-concentration titanium liquid (titanium dioxide concentration > 200 g / L). S3. Staged condensation and resource utilization of overhead gas The high-concentration water vapor discharged from the high-purity water vapor outlet 3 at the top of the tower is condensed in stages. Primary condensation: High-temperature section condensation recovers concentrated sulfuric acid (70-80% concentration), which can be directly returned to the S1 process for recycling; Secondary condensation: The dilute sulfuric acid obtained from the low-temperature condensation stage can be used for the treatment of titanium slag; Non-condensable gases (mainly SO2): are fed into the traditional titanium dioxide main production line and converted into sulfuric acid by a one-turn-one-absorption or two-turn-two-absorption acid production system, thus achieving a closed loop of sulfur. S4. Post-treatment of titanium liquid and preparation of by-products The high-concentration titanium liquid obtained is reduced and purified to meet the concentration requirements for hydrolysis. After hydrolysis, washing, and calcination, titanium dioxide product is obtained. Ferrous sulfate produced by crystallization is directly prepared into ferrous sulfate monohydrate using vacuum low-degree crystallization technology. S5. Targeted Conversion of Waste and By-products Throughout the Process Titanium slag: Dilute sulfuric acid produced in S3 is mixed with titanium slag, and soluble impurities in the titanium slag are dissolved. After filtration and washing, titanium-rich material is prepared. Acidic wastewater: after the acidic wastewater is collected, the diffusion dialysis-electrodialysis coupling membrane technology is used to recover sulfuric acid to return to production, purify water to reuse, and realize near-zero discharge of the acidic wastewater.
[0025] As shown in Figure 2 The reaction rectification column used in the sulfuric acid method titanium dioxide deep resource method based on the reaction rectification coupling device. The reaction rectification column is divided into a stripping section, a reaction rectification section and a rectification section from top to bottom. The acidolysis reaction mainly occurs in the reaction rectification section. The reaction rectification section is provided with a tray side line 5. The reaction rectification section is filled with efficient regular fillers to provide a large gas-liquid mass transfer surface area for the reaction. The rectification section is used to further purify the rising steam. The rectification section is filled with efficient regular fillers. The sulfuric acid components entrained in the steam are returned to the reaction zone in the reaction rectification column through condensation, a first pipeline 7 and a sulfuric acid return inlet 4 for reuse. The reaction rectification column is a composite column integrating reaction, evaporation, rectification and heat exchange.
[0026] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present application should also be within the scope of the present application.
Claims
1. A method for deep resource utilization of titanium dioxide by sulfuric acid process based on reaction rectification coupling device, characterized in that, The method comprises the following steps: S1. Reaction rectification coupled with acidolysis and concentration Titanium ore powder is mixed with 92%-98% concentrated sulfuric acid and fed into a reaction rectification column, the reaction rectification column provides heat for acidolysis and the acidolysis reaction is carried out at a maintained operating temperature, water and a small amount of decomposed SO3 gas generated by the acidolysis reaction move upward, the upward moving steam is in countercurrent contact with the downward moving liquid material; The mixed steam discharged from the top of the column is first condensed by a condenser, then part of the recovered concentrated sulfuric acid is sent back into the column through a reflux distributor, the sulfuric acid impurities in the steam are efficiently intercepted, and high-purity water vapor is removed from the top of the column, and an anhydrous or low-moisture titanium salt and sulfate melt is obtained at the bottom of the column; S2. Leaching of the melt and preparation of titanium liquor The melt discharged from the reaction rectification column is directly injected into water for rapid cooling leaching, and high-concentration titanium liquor is directly obtained; S3. Fractional condensation of the top steam and resource utilization The high-purity water vapor discharged from the top is subjected to fractional condensation; First-stage condensation: high-temperature section condensation to recover concentrated sulfuric acid; Second-stage condensation: low-temperature section condensation to obtain dilute sulfuric acid; Non-condensable gas: fed into a traditional titanium dioxide main production line, and converted into sulfuric acid by a one-turn-one-absorption or two-turn-two-absorption acid production system, and returned to the acidolysis process of S1 to realize sulfur closed loop; S4. Post-treatment of titanium liquor and preparation of by-products The obtained high-concentration titanium liquor meets the concentration requirement of hydrolysis after reduction and purification, and titanium dioxide is obtained after hydrolysis, washing and calcination; ferrous sulfate produced by crystallization is directly prepared into ferrous sulfate monohydrate by vacuum low-degree crystallization technology; S5. Directional conversion of waste and by-products in the whole process Titanium slag: mixed with dilute sulfuric acid produced in S3 to prepare a titanium-rich material; Acidic wastewater: after being collected, the acidic wastewater is subjected to diffusion dialysis-electrodialysis coupled membrane technology to recover sulfuric acid for reuse and purified water for reuse, achieving near-zero discharge of acidic wastewater.
2. The method according to claim 1, wherein the method is characterized in that, The column body of the reaction rectification column in S1 is made of strong acid-resistant and high-temperature-resistant materials.
3. The method according to claim 1, wherein the operating temperature in S1 is 150-200℃.
4. The method according to claim 1, wherein the method is characterized in that, The reaction rectification column in S1 is a composite column integrating reaction, evaporation, rectification and heat exchange.
5. The method according to claim 1, wherein the method is characterized in that, The reaction rectification column in S1 is divided into a stripping section, a reaction rectification section and a rectification section from top to bottom.
6. The method according to claim 5, wherein the reaction distillation coupling device is characterized in that, The reaction rectification section is provided with a column plate side line and is filled with efficient regular packing.
7. The method according to claim 5, wherein the reaction distillation coupling device is characterized in that, The rectification section is filled with efficient regular packing.
8. The method according to claim 1, wherein the method is characterized in that, The rapid cooling leaching in S2 is rapidly reduced to 20-15℃.
9. The method according to claim 1, wherein the method is characterized in that, The concentration of titanium dioxide in the high-concentration titanium liquor in S2 is >200g / L.