Titanium dioxide dilute sulfuric acid concentration system and method

Abstract

The invention discloses a titanium dioxide dilute sulphuric acid concentration system which comprises a first-stage concentration unit, a second-stage concentration unit and a third-stage concentration unit, the first-stage concentration unit is communicated with a first clear liquid tank, the first clear liquid tank is communicated with the second-stage concentration unit, the second-stage concentration unit is communicated with a first heat exchanger, and the third-stage concentration unit is communicated with a second heat exchanger. The first heat exchanger is communicated with the third-stage concentration unit, and the first clear liquid tank is connected with a cooling separation system. The method of the system comprises the following steps: S1, primary separation and concentration treatment; s2, primary evaporation and concentration treatment; s3, secondary evaporation and concentration treatment. According to the concentration process of the system and the process mode disclosed by the invention, material recovery of multiple products can be realized; according to the system and the process mode, dilute sulphuric acid does not need to be neutralized, and lime consumption and titanium gypsum generation are avoided; while the economic cost is saved, the site requirement of a production area can be reduced, and the pressure of surrounding markets on treating titanium gypsum according to the consumption capacity of lime, sulfuric acid and steam is reduced.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide dilute sulfuric acid concentration technology, specifically to a system and method for titanium dioxide dilute sulfuric acid concentration. Background Technology

[0002] The dominant product of titanium dioxide on the market is titanium dioxide powder. Each ton of titanium dioxide powder produces approximately 10.4 tons of titanium dioxide dilute sulfuric acid (equivalent to 20% sulfuric acid), which requires treatment. Currently, the treatment method is lime neutralization, with the byproduct titanium gypsum slag being outsourced to other factories for processing as a raw material. Based on an annual titanium dioxide production of 50,000 tons, the annual amount of 20% titanium dioxide dilute sulfuric acid requiring treatment reaches 520,000 tons. Accordingly, 74,300 tons of 80% lime are needed annually as a neutralizing agent, producing 249,000 tons of titanium gypsum (dry basis), which also needs to be outsourced for treatment. Based on a purchase price of 600 yuan / ton for 80% lime and an outsourced treatment fee of 50 yuan / ton for titanium gypsum slag, the annual material cost alone reaches 57.028 million yuan. Furthermore, the treatment process and the subsequent waste generated further increase environmental pressure.

[0003] The dilute sulfuric acid produced from titanium dioxide originates from waste acid in the acidification and washing processes, and its concentration varies considerably, with an average concentration of over 20% after collection. Due to the solubility characteristics of ferrous salts, the dilute sulfuric acid contains a large amount of titanates and ferrous salts. During the concentration process of dilute sulfuric acid, the solubility of titanium and iron salts changes significantly; as the concentration increases, a large amount of corresponding salts precipitates. When the sulfuric acid is concentrated to 45%, the solubility of each salt reaches a relatively stable state at different acid concentrations. Considering the characteristics of the titanium dioxide dilute sulfuric acid concentration process, proper recovery of titanium salts can improve the utilization rate of titanium ore. The recovered iron salts have good market value in the heptahydrate state; furthermore, recovery can improve the stability of dilute sulfuric acid concentration. When the dilute sulfuric acid is concentrated to an 80% acid concentration, it can be directly reused as raw material sulfuric acid for the acidolysis of titanium dioxide powder.

[0004] The current situation regarding the treatment of dilute sulfuric acid for titanium dioxide is as follows: Reusing or harmlessly treating it requires significant investment in consumable costs; however, proper treatment, effectively recovering valuable elements from the dilute sulfuric acid, can eliminate these costs and generate significant cost savings. Furthermore, the pressure of purchasing raw materials such as concentrated sulfuric acid and lime, the subsidy pressure from selling titanium gypsum, and the pressure from surrounding markets regarding raw material supply capacity and waste receiving and processing capacity will be greatly alleviated. This is of great value in reducing enterprise operating costs and mitigating regional market resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method for concentrating titanium dioxide in dilute sulfuric acid, addressing the aforementioned technical problems.

[0006] The technical solution of the present invention: A system for concentrating dilute sulfuric acid used in titanium dioxide production includes a first concentration unit, a second concentration unit, and a third concentration unit. The first concentration unit is connected to a first clear liquor tank, which is connected to the second concentration unit. The second concentration unit is connected to a first heat exchanger, which is connected to the third concentration unit. The first clear liquor tank is connected to a cooling and separation system.

[0007] The first concentration unit includes a circulating tank and a first separator. The circulating tank is connected to the first clear liquor tank through the first separator. The first separator is provided with a first discharge pipe for solid residue back to titanium residue washing. The circulating tank is provided with a feed pipe for titanium dioxide dilute sulfuric acid input.

[0008] The circulating tank is connected to a first circulating pump, which is connected to a drying kiln tail gas cooling tower. The drying kiln tail gas cooling tower is connected to the circulating tank. The drying kiln tail gas cooling tower is connected to a tail gas input pipe from the drying kiln dry dedusting tail gas and a tail gas output pipe to a drying kiln tail gas cleaning system.

[0009] The second concentration unit includes a second circulating pump, a second heat exchanger, a second evaporator, a mist eliminator, and a steam compressor connected in sequence. The second circulating pump is connected to the output end of the first clear liquor tank. The steam compressor is connected to the first heat exchanger and the second heat exchanger through a steam pipe. The first heat exchanger is connected to the second heat exchanger through a condensate water pipe.

[0010] The second heat exchanger is connected to a steam and hot water shared system. The steam compressor is connected to a steam discharge pipe.

[0011] The second evaporator is connected to a centrifugal separation system. The liquid outlet of the centrifugal separation system is connected to the first clear liquor tank. The solid discharge outlet of the centrifugal separation system is connected to a cooling and separation system. The cooling and separation system is connected to a second discharge pipe for discharging iron sulfate heptahydrate.

[0012] The third concentration unit includes a first evaporator and a second separator. The input end of the first evaporator is connected to the first heat exchanger. The output end of the first evaporator is connected to the second separator. The liquid outlet of the second separator is connected to a concentrated acid discharge pipe to an acidification tank.

[0013] The input end of the second separator is connected to the mist eliminator. The output end of the second separator is connected to a third discharge pipe for discharging solids. The steam input end of the mist eliminator is connected to the first evaporator.

[0014] The liquid outlet of the second separator is also connected to a second clear liquor tank. The output end of the second clear liquor tank is connected to a third circulating pump. The output end of the third circulating pump is connected to the first heat exchanger. The input end of the second clear liquor tank is also connected to the cooling and separation system.

[0015] A method for titanium white powder dilute sulfuric acid concentration system, comprising the following steps: S1. Primary separation concentration treatment, 20% dilute sulfuric acid is input to the circulating tank through the feed pipe and the drying kiln tail gas cooling tower, after circulating tank treatment, into the first separator, after first separator treatment, solid residue is discharged through the first discharge pipe, and the liquid enters the first clear liquid tank; S2. First evaporation concentration treatment, in step S1, the liquid in the first clear liquid tank is sequentially subjected to evaporation concentration treatment by the second circulating pump, the second heat exchanger and the second evaporator, the liquid enters the centrifugal separation system, after centrifugal separation system treatment, the liquid returns to the first clear liquid tank for circulation, the solid enters the cooling separation system, after cooling separation system treatment, the solid residue is discharged through the second discharge pipe, the liquid enters the first clear liquid tank and the second clear liquid tank for continuous treatment, and the steam treated by the second evaporator enters the mist droplet remover, the liquid treated by the mist droplet remover enters the second separator, and the gas enters the steam compressor, after steam compressor treatment, the steam enters the first heat exchanger, the second heat exchanger and the steam discharge pipe, respectively, the condensed water treated by the second heat exchanger enters the steam and hot water sharing system, and is discharged after steam and hot water sharing system treatment; S3. Second evaporation concentration treatment, the liquid in the second clear liquid tank enters the first heat exchanger through the third circulating pump, at the same time, part of the steam treated by the steam compressor also enters the first heat exchanger and the second heat exchanger, and the condensed water produced by the first heat exchanger cooling also enters the second heat exchanger; the liquid enters the first evaporator, after first evaporator concentration evaporation treatment, the gas produced enters the mist droplet remover, and the liquid enters the second separator, after second separator treatment, the solid is discharged through the third discharge pipe, part of the liquid enters the second clear liquid tank again, and the other part of the liquid is transported to the acidification tank through the concentrated acid discharge pipe, and 60% concentrated dilute sulfuric acid is obtained.

[0016] The beneficial effects of the present application are: The whole dilute sulfuric acid concentration of the system and process mode of the application does not need external steam supply; the cooling water circulation cooling of the whole concentration process is the clear water system, without unorganized emission pollution and direct emission pollution. The concentration process of the system and process mode of the application can realize the material recycling of multiple products; the system and process mode of the application does not need to neutralize the dilute sulfuric acid, without consumption of lime and production of titanium gypsum; while saving the economic cost, the site demand of the production area can be reduced, the dependence of the surrounding market on lime, sulfuric acid, steam consumption capacity and the pressure of handling titanium gypsum can be reduced. The dilute sulfuric acid concentration process of the system and process mode of the application separates the crystalline salt according to the solubility physical characteristics of each salt in the titanium white dilute sulfuric acid, so as to ensure that the concentrated dilute sulfuric acid system can realize long-term stable operation; the system and process mode of the application can select vacuum cascade concentration, so that the whole concentration process can be carried out at a lower temperature, the material of the concentration equipment can be economically and reliably selected, so that the system operation has more reliable cost performance and safety. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the process flow chart of the application; Figure 2 is the solubility curve diagram of ferrous sulfate in dilute sulfuric acid. DETAILED DESCRIPTION

[0018] REFERENCE Figure 1 A titanium dioxide dilute sulfuric acid concentration system, comprising a first concentration unit, a second concentration unit and a third concentration unit, the first concentration unit is communicated with a first clear liquid tank, the first clear liquid tank is communicated with the second concentration unit, the second concentration unit is communicated with a first heat exchanger, the first heat exchanger is communicated with the third concentration unit, and the first clear liquid tank is connected with a cooling and separation system.

[0019] The first concentration unit comprises a circulating tank and a first separator, the circulating tank is communicated with the first clear liquid tank through the first separator, the first separator is provided with a first discharge pipe for solid residue back to titanium residue washing, and the circulating tank is provided with a feed pipe for titanium dioxide dilute sulfuric acid input. The first concentration unit is mainly arranged to facilitate the preliminary concentration treatment of 26% titanium dioxide dilute sulfuric acid containing titanium and iron mixture, separate out the solid residue containing titanium residue and the mixed liquid containing 44% dilute sulfuric acid.

[0020] The circulating tank is connected with a first circulating pump, the first circulating pump is connected with a drying kiln tail gas cooling tower, the drying kiln tail gas cooling tower is connected with the circulating tank, and the drying kiln tail gas cooling tower is connected with a tail gas input pipe from the drying kiln dry dedusting tail gas and a tail gas output pipe to the drying kiln tail gas cleaning system. The arrangement is mainly to facilitate the circulating treatment of the drying kiln tail gas, improve the utilization rate of the tail gas and reduce the environmental pollution caused by direct emission of the tail gas.

[0021] The secondary concentration unit comprises a second circulating pump, a second heat exchanger, a second evaporator, a mist droplet demister and a steam compressor connected in sequence, the second circulating pump is connected with the output end of the first clear liquid tank, the steam compressor is connected with the first heat exchanger and the second heat exchanger through a steam pipe, and the first heat exchanger is connected with the second heat exchanger through a condensate water pipe.

[0022] The second heat exchanger is connected with a steam and hot water sharing system, and the steam compressor is connected with a steam discharge pipe.

[0023] The second evaporator is connected with a centrifugal separation system, the liquid outlet of the centrifugal separation system is communicated with the first clear liquid tank, the solid discharge port of the centrifugal separation system is connected with a cooling separation system, and the cooling separation system is connected with a second discharge pipe for discharging ferric sulfate heptahydrate.

[0024] The secondary concentration unit is mainly used for preliminary evaporation concentration treatment of the dilute sulfuric acid mixed liquid after the preliminary concentration treatment, so as to obtain a mixed liquid, steam and corresponding solid by-products after the preliminary evaporation concentration treatment. Specifically, part of the high-temperature sulfur-containing steam is generated at the second heat exchanger, and the high-temperature sulfur-containing steam enters the steam and hot water sharing system for regrinding and slurry mixing, tail washing and water supplementing and filtering treatment.

[0025] The steam generated by the second evaporator enters the mist droplet demister and the steam compressor in sequence for treatment, and the steam treated by the steam compressor is divided into three parts, one part of which is discharged through the steam discharge pipe for external supply, and the other two parts enter the first heat exchanger and the second heat exchanger for re-treatment.

[0026] The mixed liquid generated by the second evaporator enters the centrifugal separation system for centrifugal treatment, and the generated mixed liquid enters the first clear liquid tank for circulation again, and the generated fixed by-products enter the cooling separation system, and the liquid mixture generated after the fixed by-products are treated by the cooling separation system enters the first clear liquid tank and the second clear liquid tank for continuous circulation treatment, and the solid by-products are rich in ferric sulfate heptahydrate, and the solid by-products rich in ferric sulfate heptahydrate are discharged through the second discharge pipe.

[0027] The tertiary concentration unit comprises a first evaporator and a second separator, the input end of the first evaporator is connected with the first heat exchanger, the output end is connected with the second separator, and the liquid outlet of the second separator is connected with a thick acid discharge pipe leading to an acidification tank.

[0028] The input end of the second separator is connected with the mist droplet demister, and the output end is connected with a third discharge pipe for discharging solids, and the steam input end of the mist droplet demister is connected with the first evaporator.

[0029] The liquid outlet end of the second separator is also connected with a second clean liquid tank, the output end of the second clean liquid tank is connected with a third circulating pump, the output end of the third circulating pump is connected with the first heat exchanger, and the input end of the second clean liquid tank is also connected with the cooling separation system.

[0030] In the present application, the centrifugal separation system, the cooling separation system and the steam and hot water sharing system all adopt the conventional treatment technology of sulfuric acid in the prior art, which will not be described in detail in the present application.

[0031] The three-stage concentration unit is convenient for concentrating the high-temperature sulfur-containing steam provided by the steam compressor and the sulfuric acid mixed liquid provided by the second clean liquid tank.

[0032] Specifically, the sulfuric acid mixed liquid provided by the second clean liquid tank is processed by the third circulating pump and enters the first heat exchanger, the first heat exchanger is connected with the high-temperature sulfur-containing steam provided by the steam compressor, after the heat exchange treatment of the first heat exchanger, the remaining sulfur-containing steam enters the second heat exchanger, and the obtained mixed liquid enters the first evaporator, after the treatment of the first evaporator, the generated steam enters the mist eliminator for treatment, and the solid by-product generated by the treatment of the mist eliminator enters the second separator, at the same time, the mixed liquid generated after the treatment of the first evaporator also enters the second separator, after the treatment of the second separator, the solid residue containing ferrous sulfate monohydrate is discharged through the third discharge pipe for use in the production of sulfuric acid; and the liquid generated by the treatment of the second separator is a thick liquid, which is divided into two parts, one part enters the second clean liquid tank for continuous circulation, and the other part is discharged into the acidification tank through the thick acid discharge pipe to obtain 60% dilute sulfuric acid.

[0033] In the present application, the first evaporator and the second evaporator are dilute sulfuric acid evaporators; the first heat exchanger and the second heat exchanger are graphite heat exchangers; the first separator and the second separator are crystalline horizontal spiral separators; the steam compressor is an MVR steam compressor; the dilute sulfuric acid evaporator, the graphite heat exchanger and the crystalline horizontal spiral separator all adopt the conventional equipment in the prior art of sulfuric acid treatment, which will not be described in detail in the present application.

[0034] A method for a titanium dioxide dilute sulfuric acid concentration system, comprising the following steps: S1. Primary separation and concentration treatment, 20% dilute sulfuric acid is input into the circulating tank through the feed pipe and the drying kiln tail gas cooling tower, after the treatment of the circulating tank, it enters the first separator, after the treatment of the first separator, the solid residue is discharged through the first discharge pipe, and the liquid enters the first clean liquid tank; S2. The first evaporation concentration treatment, in step S1, the liquid in the first clear liquid tank is sequentially subjected to evaporation concentration treatment by the second circulating pump, the second heat exchanger and the second evaporator. The liquid enters the centrifugal separation system, and after treatment by the centrifugal separation system, the liquid returns to the first clear liquid tank for circulation. The solid enters the cooling separation system, and after treatment by the cooling separation system, the solid residue is discharged through the second discharge pipe. The liquid enters the first clear liquid tank and the second clear liquid tank for further treatment. The steam treated by the second evaporator enters the mist droplet demister. The liquid treated by the mist droplet demister enters the second separator. The gas enters the steam compressor. After treatment by the steam compressor, the steam enters the first heat exchanger, the second heat exchanger and the steam discharge pipe. The condensed water treated by the second heat exchanger enters the steam and hot water sharing system, and is discharged after treatment by the steam and hot water sharing system. S3. The second evaporation concentration treatment, the liquid in the second clear liquid tank enters the first heat exchanger through the third circulating pump. At the same time, part of the steam treated by the steam compressor also enters the first heat exchanger and the second heat exchanger. The condensed water produced by the first heat exchanger is also introduced into the second heat exchanger. The liquid enters the first evaporator, and after evaporation concentration treatment by the first evaporator, the gas produced enters the mist droplet demister. The liquid enters the second separator, and after treatment by the second separator, the solid is discharged through the third discharge pipe. Part of the liquid reenters the second clear liquid tank, and the other part of the liquid is transported to the acidification tank through the thick acid discharge pipe to obtain 60% concentrated sulfuric acid.

[0035] Reference Figure 2 In actual production, in the mixed titanium and iron dilute sulfuric acid, when the concentration of dilute sulfuric acid is below 25-28%, the solubility of metatitanic acid and ferrate will decrease rapidly with the increase of the concentration of dilute sulfuric acid, and when the concentration of sulfuric acid reaches nearly 26%, metatitanate almost completely precipitates. At this time, the main components of the precipitated titanium and iron salts are titanate and ferrous sulfate salt. Recycling and re-entering the titanate washing can effectively improve the recovery rate of titanium, and the ferrous salt will be dissolved again and recycled to the dilute sulfuric acid or the ferrous sulfate in the preliminary sulfuric acid cooling and salt precipitation. Thus, the utilization rate of titanium ore and the output rate of ferrous sulfate are improved, and the effective output value is increased.

[0036] When the sulfur concentration of dilute sulfuric acid is 26-40% and the temperature is below 65℃, the main dissolved substance in titanium white dilute sulfuric acid is ferrous sulfate salt, and the solubility of iron salt will decrease rapidly during the concentration of dilute sulfur. When the concentration of sulfuric acid is 40% or more, the solubility of iron salt tends to be stable. At this time, the concentration of dilute sulfuric acid is separated, and a large amount of ferrous sulfate heptahydrate can be produced. Not only can the heat exchanger be avoided, but also valuable ferrous sulfate heptahydrate precipitate can be obtained.

[0037] The various properties of the iron salt are as follows: during the concentration process of dilute sulfuric acid with a concentration of 40-60%, the solubility of each iron salt tends to be stable, and the ferrous sulfate heptahydrate still existing at high temperature (more than 65℃) will dehydrate into ferrous sulfate with low crystallization water: ferrous sulfate monohydrate and dihydrate. The market value of this part of ferrous sulfate with low crystallization water will be significantly reduced, and when the amount is large, the heater will be seriously blocked due to the small size of the crystal, the dense and difficult water-soluble scale formed by the precipitation, etc. A small amount of product precipitated by the acid can be used for sulfuric acid production roasting with ore, improving the quality of sulfuric acid burning iron slag. By controlling the concentration of dilute sulfuric acid and separating the precipitated salt in time, the concentration process of dilute sulfuric acid will not produce obvious scaling, and the concentration of sulfuric acid has good stability.

[0038] The boiling point of sulfuric acid is much higher than that of water, and the corrosion of sulfuric acid will be significantly enhanced at high temperature. In order to reduce the temperature level of energy supply for concentration and reduce the requirement for equipment material, vacuum concentration is adopted for the whole process of sulfuric acid concentration: the whole is a cascade vacuum concentration.

[0039] The condition for the existence of ferrous sulfate in the form of heptahydrate in dilute sulfuric acid is that the concentration is less than 43% and the temperature is less than 65℃; in low-concentration and low-temperature titanium white dilute sulfuric acid, the solubility of iron salt will decrease rapidly when the concentration increases, and the solubility value is basically stable and very small when the concentration reaches 43%; the increase of dilute acid temperature will cause the crystallization water of ferrous sulfate to be extremely unstable, and when the temperature is higher than 65℃, the heptahydrate crystal will dehydrate into monohydrate and dihydrate, which will have little effect on production when the amount is not large; The crystallization state of ferrous sulfate: the heptahydrate crystal particles are coarse, the formed precipitate pile has a large specific gravity, and it is easy to be dissolved in water; when there is scaling in the heater, it can be washed with water. The monohydrate and dihydrate crystal particles are small, the formed particles are small, the formed precipitate pile has a small specific gravity, and it is easy to be hydrated at the interface, which will cause serious scaling and blockage when the amount is large, and it is difficult to dissolve the monohydrate and dihydrate crystal in water, so it is difficult to clean the heater. In production, the existence of low-concentration amount should be controlled to ensure the stability of the heat exchange system. At the same time, the ferrous phosphate salt taken out also has high activity only in the form of heptahydrate, which can be used as raw material for lithium iron phosphate, and the monohydrate and dihydrate crystals can only be used for sulfuric acid production.

[0040] The energy recovery COP of the system and process of the present application is 5.0, and the whole concentration of dilute sulfuric acid does not need external steam supply; the cooling water circulation cooling of the whole concentration process is a clear water system, which has no unorganized emission pollution and direct emission pollution.

[0041] COP is the abbreviation of Coefficient of Performance, which is usually translated as performance coefficient in Chinese. It is a core indicator to measure the energy efficiency of energy recovery systems, heat pumps, refrigeration systems and other energy conversion equipment. COP is 5.0, which means that for every unit of driving energy (such as electricity) consumed, 5 units of useful energy (such as heat energy that can be used for concentration) can be recovered.

[0042] The concentration process of the system and process of the present application can achieve multi-product material recovery. For example, concentrating 520,000 tons of 20% titanium white dilute sulfuric acid per year can recover 26,800 tons of titanium slag, 41,600 tons of ferrous sulfate heptahydrate, 2,400 tons of ferrous sulfate monohydrate, and 10,800 tons of steam. 80% sulfuric acid 106,000 tons.

[0043] The system and process of the present application do not require neutralization treatment of dilute sulfuric acid, and there is no consumption of lime and production of titanium gypsum. At the same time, it can save economic costs, reduce the site requirements of the production area, and reduce the dependence of the surrounding market on lime, sulfuric acid, steam consumption capacity and the pressure of handling titanium gypsum.

[0044] The dilute sulfuric acid concentration process of the system and process of the present application separates the crystalline salt according to the solubility physical properties of each salt in titanium white dilute sulfuric acid, ensuring that the dilute sulfuric acid concentration system can operate stably for a long time. The system and process of the present application use vacuum cascade concentration, which allows the entire concentration process to be carried out at a lower temperature. It can economically and reliably select the material of the concentration equipment, making the system operation more reliable in terms of cost performance and safety.

Claims

1. A system for concentrating titanium dioxide in dilute sulfuric acid, characterized in that... It includes a primary concentration unit, a secondary concentration unit, and a tertiary concentration unit. The primary concentration unit is connected to a first clear liquid tank, the first clear liquid tank is connected to a secondary concentration unit, the secondary concentration unit is connected to a first heat exchanger, the first heat exchanger is connected to the tertiary concentration unit, and the first clear liquid tank is connected to a cooling separation system.

2. The titanium dioxide dilute sulfuric acid concentration system according to claim 1, characterized in that: The primary concentration unit includes a circulation tank and a first separator. The circulation tank is connected to the first clear liquid tank through the first separator. The first separator is equipped with a first discharge pipe for washing solid slag back to titanium slag. The circulation tank is equipped with a feed pipe for inputting dilute sulfuric acid into titanium dioxide.

3. The titanium dioxide dilute sulfuric acid concentration system according to claim 2, characterized in that: The circulation tank is connected to a first circulation pump, and the first circulation pump is connected to a drying kiln tail gas cooling tower. The drying kiln tail gas cooling tower is connected to the circulation tank and is connected to a tail gas input pipe from the tail gas after the dry dust removal of the drying kiln and a tail gas output pipe to the drying kiln tail gas cleaning system.

4. The titanium dioxide dilute sulfuric acid concentration system according to claim 1, characterized in that: The secondary concentration unit includes a second circulating pump, a second heat exchanger, a second evaporator, a mist demister, and a steam compressor connected in sequence. The second circulating pump is connected to the output end of the first clear liquid tank. The steam compressor is connected to the first heat exchanger and the second heat exchanger through a steam pipe. The first heat exchanger is connected to the second heat exchanger through a condensate pipe.

5. The titanium dioxide dilute sulfuric acid concentration system according to claim 4, characterized in that: The second heat exchanger is connected to a shared steam and hot water system, and the steam compressor is connected to a steam exhaust pipe.

6. The titanium dioxide dilute sulfuric acid concentration system according to claim 4, characterized in that: The second evaporator is connected to a centrifugal separation system. The liquid outlet of the centrifugal separation system is connected to the first clear liquid tank. The solid discharge outlet of the centrifugal separation system is connected to a cooling separation system. The cooling separation system is connected to a second discharge pipe for discharging ferric sulfate heptahydrate.

7. The titanium dioxide dilute sulfuric acid concentration system according to claim 4, characterized in that: The three-stage concentration unit includes a first evaporator and a second separator. The input end of the first evaporator is connected to the first heat exchanger, and the output end is connected to the second separator. The liquid outlet end of the second separator is connected to a concentrated acid discharge pipe leading to the acidification tank.

8. The titanium dioxide dilute sulfuric acid concentration system according to claim 7, characterized in that: The input end of the second separator is connected to the mist demister, and the output end is connected to a third discharge pipe for discharging solids. The steam input end of the mist demister is connected to the first evaporator.

9. The titanium dioxide dilute sulfuric acid concentration system according to claim 7, characterized in that: The outlet of the second separator is also connected to a second clear liquid tank, the output of the second clear liquid tank is connected to a third circulation pump, the output of the third circulation pump is connected to the first heat exchanger, and the input of the second clear liquid tank is also connected to the cooling separation system.

10. A method for a titanium dioxide dilute sulfuric acid concentration system according to any one of claims 1-10, characterized in that: Includes the following steps: S1. Primary separation and concentration treatment: 20% dilute acid is fed into the circulation tank through the feed pipe and the tail gas cooling tower of the drying kiln. After the circulation tank is processed, it enters the first separator. After the first separator is processed, the solid residue is discharged through the first discharge pipe, and the liquid enters the first clear liquid tank. S2. Primary evaporation and concentration treatment: In step S1, the liquid inside the first clear liquid tank is sequentially evaporated and concentrated through the second circulating pump, the second heat exchanger, and the second evaporator. The liquid enters the centrifugal separation system. After being processed by the centrifugal separation system, the liquid returns to the first clear liquid tank for circulation. The solid enters the cooling separation system. After being processed by the cooling separation system, the solid residue is discharged through the second discharge pipe. The liquid enters the first clear liquid tank and the second clear liquid tank for further processing. The steam after being processed by the second evaporator enters the mist demister. The liquid after being processed by the mist demister enters the second separator. The gas enters the steam compressor. After being processed by the steam compressor, the steam enters the first heat exchanger, the second heat exchanger, and the steam discharge pipe. The condensate after being processed by the second heat exchanger enters the steam and hot water combined system. After being processed by the steam and hot water combined system, it is discharged. S3. Two-stage evaporation and concentration treatment: The liquid in the second clear liquid tank enters the first heat exchanger via the third circulation pump. At the same time, some of the steam processed by the steam compressor also enters the first and second heat exchangers. The condensate produced by the cooling in the first heat exchanger also enters the second heat exchanger. The liquid enters the first evaporator. After concentration and evaporation in the first evaporator, the generated gas enters the mist demister, while the liquid enters the second separator. After processing in the second separator, the solid is discharged through the third discharge pipe. Part of the liquid re-enters the second clear liquid tank, and the other part of the liquid is transported to the acidification tank through the concentrated acid discharge pipe to obtain concentrated 60% dilute sulfuric acid.

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