Water-saving, emission-reducing and iron-reducing titanium dioxide slurry washing device and process for increasing low-iron waste acid washing in sulfuric acid process titanium dioxide production

Abstract

The invention discloses a water-saving, emission-reducing and iron-reducing titanium dioxide slurry washing process for increasing low-iron waste acid washing in sulfuric acid process titanium dioxide production, the process comprises the steps of slurry loading, low-iron waste acid washing, clear water washing, stirring and pulping, slurry conveying and the like, and low-iron waste acid is prepared by mixing a specific washing solution and loading mother liquor in proportion and performing membrane filtration. The device comprises a crane, a washing vacuum leaf filter, washing tanks, a horizontal beating tank, a slurry conveying pump and the like. Compared with a traditional process, the method has the advantages that the treatment capacity per hour is improved, the clear water consumption per ton of TiO2 is reduced by half, the iron content of a filter cake is reduced, the product quality is improved, the process is simplified, the equipment investment, the workload and the energy consumption are reduced, and the method has the advantages of saving water, reducing emission and improving the production efficiency and the product quality, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide production, and particularly to a titanium white slurry washing device and process for water saving, emission reduction and iron reduction by adding low-iron waste acid washing in sulfuric acid process titanium white production.

Background Art

[0002] In the production of sulfuric acid process titanium dioxide, the washing operation of the hydrolyzed slurry is of great significance. Its main purpose is to remove various water-soluble impurities mainly in the form of FeSO 4 from the slurry to obtain a pure washed slurry, which lays a foundation for calcining high-quality titanium dioxide subsequently. There are two key indicators in this process, which have a profound impact on product quality and production cost. On the one hand, the lower the iron content of the washed product, the higher the quality of both anatase and rutile titanium dioxide. When the Fe n+ content in titanium dioxide exceeds 0.01%, the hue and pigment properties will decrease significantly. Even below this value, reducing the iron content can still improve the quality. On the other hand, the water consumption for washing titanium white slurry accounts for more than 80% of the total production water consumption. Reducing its water consumption can not only greatly reduce the water resource cost, but also reduce the amount of sewage generated, thereby reducing the high environmental protection treatment cost.

[0003] The main impurities of the titanium white slurry to be washed are H 2 SO 4 and FeSO 4 , among which FeSO 4 has the greatest impact on the quality of titanium dioxide, while H 2 SO 4 will decompose and volatilize during the calcination process and is not sensitive to the quality. The washing principle is to continuously dilute and carry away water-soluble impurities represented by FeSO 4 with an aqueous solution. Therefore, controlling the washing water consumption and the impurity content of the slurry (marked by the iron content) has always been an important topic explored in the industry. The current better level in the industry is that the iron content of the slurry is about 0.0045%, and the fresh water consumption for washing per ton of titanium dioxide is 20m 3 , and there is still room for improvement.

[0004] In the production operation of titanium dioxide by sulfuric acid process, vacuum leaf filters and plate filters are commonly used for the filtration separation and washing of titanium dioxide hydrolysis slurry. The vacuum leaf filter belongs to the open-flow washing method. The process of installing the filter plate, the thickness of the slurry, and the washing condition can be observed and adjusted throughout the process. The washing is stable, but the equipment is large, the labor intensity of workers is high, and the water consumption is slightly more. However, by using secondary beating, bleaching, and washing, the iron content in the slurry can be reduced to less than 0.0035%, which is an ideal method for producing low-iron and high-performance products. The plate filter is for positive-pressure separation, filtration, and washing, belonging to the underflow washing method. The thickness of the filter cake and the washing condition cannot be directly observed and detected, but can only be indirectly predicted. The equipment is compact, less manpower is used, and after secondary beating, bleaching, and washing, the iron content in the slurry can only be reduced to less than 0.0050%. Although these two methods cannot operate continuously, after secondary beating, bleaching, and washing, the iron content can be reduced to less than 0.005%, which can meet the basic requirements for the manufacture of medium and high-grade titanium dioxide.

[0005] The "Titanium Dioxide Slurry Continuous Washing Device and Its Use Method" with the publication number CN107758733A announced on February 4, 2020, is different from the leaf filter and the plate filter. It focuses on the continuous filtration and washing of the slurry, realizes the continuous process of feeding - washing and filtering - discharging, can reduce water consumption and increase production capacity, but is not helpful for reducing the iron content in the titanium dioxide slurry. And the titanium dioxide slurry washing process of the present invention for sulfuric acid process titanium dioxide production, which increases low-iron waste acid washing to save water, reduce emissions, and reduce iron, belongs to the innovative process of the leaf filter device method. By adding low-iron waste acid washing in the leaf filter device method, not only the secondary beating and bleaching process is omitted, but also the iron content of the slurry and the water consumption for washing are significantly reduced.

[0006] The disclosure of the above background technical content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. Without clear evidence indicating that the above content was publicly available on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and inventiveness of this application.

Summary of the Invention

[0007] The purpose of the present invention is to propose a titanium dioxide slurry washing device and process for sulfuric acid process titanium dioxide production, which increases low-iron waste acid washing to save water, reduce emissions, and reduce iron, so as to solve the technical problems existing in the above prior art.

[0008] For this reason, the present invention adopts the following technical solutions:

[0009] A titanium dioxide slurry washing device for sulfuric acid process titanium dioxide production, which increases low-iron waste acid washing to save water, reduce emissions, and reduce iron, includes a crane, a water-washing vacuum leaf filter, a slurry filter plate installation pool, a low-iron waste acid washing pool, a clean water washing pool, a horizontal beating tank, and a slurry transfer pump;

[0010] Among them, the crane is installed on the rail about 9 - 11 m above the reference ground; the water-washing vacuum leaf filter is lifted by the crane; the slurry loading tank, the low-iron waste acid washing tank, the clean water washing tank, and the horizontal beating tank are installed on the reference ground and arranged in sequence in the same direction; the slurry delivery pump is installed on the reference ground near the discharge end of the horizontal beating tank, and its feed inlet is connected to the lowest point of the horizontal beating tank.

[0011] Function of the crane: The crane is responsible for lifting the vacuum leaf filter. The vacuum leaf filter is lifted to the slurry loading tank for loading operation. During this process, when the filter cake thickness reaches 37 - 43 mm, the loading stops, and it is lifted for draining. Then, the crane lifts the drained vacuum leaf filter to the low-iron waste acid washing tank for washing. After the washing meets the requirements, it is lifted again for draining. Subsequently, it is lifted to the clean water washing tank for continuous washing, and it is also lifted for draining after reaching the washing standard. After that, the crane lifts the vacuum leaf filter above the horizontal beating tank for flaking and stirring beating operation. Finally, the evenly stirred and beaten slurry is transported by the slurry delivery pump to the next station for processing, and this cycle is repeated to complete the washing operation of the titanium white slurry.

[0012] Furthermore, the components of the vacuum leaf filter include a vacuum leaf filter frame, vacuum blades, a vacuum connection pipe of the vacuum leaf filter, a vacuum storage tank, and a vacuum control valve of the vacuum leaf filter; the vacuum blades are hung under the vacuum leaf filter frame; the vacuum connection pipe of the vacuum leaf filter is installed above the vacuum leaf filter frame, the vacuum storage tank is installed on the upper right side of the vacuum leaf filter frame, and the vacuum control valve of the vacuum leaf filter is installed at the front end of the vacuum leaf filter frame.

[0013] Functions of each component of the vacuum leaf filter: The vacuum leaf filter frame serves to connect, fix, and support the other components that make up the vacuum leaf filter. The vacuum blades are used for related filtering operations. One end of the vacuum connection pipe of the vacuum leaf filter is connected to the flange of the vacuum control valve of the vacuum leaf filter, and the other end is connected to the end of the vacuum storage tank, serving to transmit vacuum, etc. The vacuum storage tank provides a certain gas storage function for the system. The vacuum control valve of the vacuum leaf filter is used to control related vacuum processes. The overall vacuum leaf filter composed of these components can realize operations such as loading of the slurry, washing with low-iron waste acid, and washing with clean water, and after the slurry becomes a qualified product, it is sent to the next process through flaking and beating.

[0014] Furthermore, the components of the slurry loading tank include a slurry delivery pipe, a slurry control valve, a vacuum connection pipe for slurry loading, and a vacuum air-lock valve for slurry loading; among them, the slurry delivery pipe is arranged at the rear end of the slurry loading tank, and the slurry control valve is installed at the position of the slurry delivery pipe near the rear end of the slurry loading tank; the vacuum connection pipe for slurry loading is arranged at the lower front end of the slurry loading tank, and the vacuum air-lock valve for slurry loading is connected to the vacuum connection pipe for slurry loading and fixed at the middle front end of the slurry loading tank.

[0015] Functions of each component of the slurry loading tank: The slurry conveying pipe is used to convey the hydrolyzed slurry to the slurry loading tank. The slurry control valve can control the inflow of the hydrolyzed slurry. When it is opened, the hydrolyzed slurry can enter the slurry loading tank, and when it is closed after reaching the required liquid level, the feeding can be stopped. The slurry loading vacuum connecting pipe and the slurry loading vacuum air-lock valve are used in combination. After the vacuum control valve of the vacuum leaf filter on the water-washing vacuum leaf filter is docked with them, and the relevant valves are opened in sequence, the slurry loading operation can start. During the whole loading process, by opening and adjusting the slurry control valve again, the liquid level of the slurry in the tank can be kept constant, ensuring the smooth progress of the loading operation until the thickness of the loaded material reaches 37 - 43 mm. Then, the relevant valves are closed and the material is lifted and drained to complete the loading operation.

[0016] Furthermore, the components of the low-iron waste acid washing tank include a waste acid conveying pipe, a waste acid control valve, a waste acid washing vacuum connecting pipe, and a waste acid washing vacuum air-lock valve; the waste acid conveying pipe is located at the rear end of the low-iron waste acid washing tank, and the waste acid control valve is installed at the position of the waste acid conveying pipe close to the rear end of the low-iron waste acid washing tank; the waste acid washing vacuum connecting pipe is arranged at the lower part of the front end of the low-iron waste acid washing tank, and the waste acid washing vacuum air-lock valve is connected to the waste acid washing vacuum connecting pipe and fixed at the middle part of the front end of the low-iron waste acid washing tank.

[0017] Functions of each component of the low-iron waste acid washing tank: The waste acid conveying pipe is used to convey the low-iron waste acid to the washing tank. The waste acid control valve controls the inflow of the low-iron waste acid. When it is opened, the low-iron waste acid can enter the washing tank, and when it is closed after reaching the required liquid level, the acid feeding can be stopped. The waste acid washing vacuum connecting pipe and the waste acid washing vacuum air-lock valve cooperate with the corresponding components on the water-washing vacuum leaf filter. After docking and opening the relevant valves, the low-iron waste acid washing process is started. During the washing process, by opening and adjusting the waste acid control valve again, the liquid level of the low-iron waste acid in the tank can be kept constant, ensuring the washing effect. After the washing reaches the requirements, the relevant valves are closed and the material is lifted and drained to complete the low-iron waste acid washing operation.

[0018] Furthermore, the components of the clean water washing tank include a clean water conveying pipe, a clean water control valve, a clean water washing vacuum connecting pipe, and a clean water washing vacuum air-lock valve, etc.; among them, the clean water conveying pipe is located at the rear end of the clean water washing tank, and the clean water control valve is installed at the position of the clean water conveying pipe close to the rear end of the clean water washing tank; the clean water washing vacuum connecting pipe is arranged at the lower part of the front end of the clean water washing tank, and the clean water washing vacuum air-lock valve is connected to the clean water washing vacuum connecting pipe and fixed at the middle part of the front end of the clean water washing tank.

[0019] Functions of components of the fresh water washing tank: The fresh water delivery pipe is used to deliver fresh water to the fresh water washing tank. The fresh water control valve can control the inflow of fresh water. When it is opened, fresh water can enter the fresh water washing tank, and when it is closed after reaching the required liquid level, the water inlet can be stopped. The fresh water washing vacuum connection pipe and the fresh water washing vacuum air-lock valve cooperate with the corresponding components on the water washing vacuum leaf filter. After docking and opening the relevant valves, the fresh water washing process can be started. During the washing process, opening and adjusting the fresh water control valve again can keep the liquid level of fresh water in the tank constant, ensuring the washing effect. After the washing reaches the requirements, close the relevant valves and lift to drain, completing the fresh water washing operation.

[0020] Further, the components of the horizontal beating tank include a leaf filter support frame; the leaf filter support frame is installed above the horizontal beating tank. The support top beam of the leaf filter support frame is 1.8 - 2.0 m higher than the surface of the horizontal beating tank, and its four support legs are supported on the reference ground.

[0021] Functions of the horizontal beating tank and its components: The leaf filter support frame is used to place the filter cake that has been dried by fresh water washing and transported by the vacuum leaf filter. It provides a stable placement platform for subsequent operations. During the flaking and stirring beating operation, first place the filter cake stably on the leaf filter support frame, then use pressure water to wash the filter cake into the horizontal beating tank, and then the horizontal beating tank stirs and beats the filter cake that has fallen into it, thus completing the flaking and stirring beating operation, making the materials mix evenly and facilitating subsequent processing.

[0022] Further, the slurry delivery pump is a plastic-lined wear-resistant and corrosion-resistant slurry pump, installed at a position on the reference ground and close to the front end of the horizontal beating tank. Its feed inlet is connected to the lowest point of the horizontal beating tank, and the upper culvert delivery pipe leads to the salt treatment tank.

[0023] Function of the slurry delivery pump: The slurry delivery pump is mainly used to deliver slurry. In the final stage of the titanium white slurry washing operation, the slurry that has been evenly stirred and has good fluidity in the horizontal beating tank is sucked in from its feed inlet, and then pumped to the salt treatment station, thus completing the material transfer work from the horizontal beating tank to the salt treatment station in the entire titanium white slurry washing process, ensuring the coherence of the production process.

[0024] A titanium white slurry washing process for sulfuric acid process titanium white production that increases low-iron waste acid washing to save water, reduce emissions and reduce iron, specifically includes the following steps:

[0025] (1) Titanium white slurry feeding operation: The titanium white slurry to be washed is injected into the slurry feeding tank. When the liquid level reaches 52%-60% of the tank's own volume, close the slurry control valve; The crane hoists the vacuum leaf filter to the slurry feeding tank. After the vacuum control valve of the vacuum leaf filter on the vacuum leaf filter is accurately docked with the slurry feeding vacuum air-lock valve of the slurry feeding tank, open these two valves in sequence to start the feeding operation. During the feeding operation, open and adjust the slurry control valve again to ensure that the slurry liquid level in the tank remains constant all the time; When the filter cake thickness reaches 37-43 mm, complete the feeding operation, and close the vacuum control valve of the vacuum leaf filter, the slurry feeding vacuum air-lock valve and the slurry control valve in sequence. Then lift the filter cake and drain it;

[0026] (2) Low-iron waste acid washing step: Inject the low-iron waste acid with H 2 SO 4 content of 35-39 g / L and FeSO 4 content of 0.1-0.15 g / L into the low-iron waste acid washing tank until the liquid level reaches 52-60% of the tank's own volume, and then close the waste acid control valve; The crane hoists the vacuum leaf filter that has completed the feeding operation in step (1) to the low-iron waste acid washing tank. After the vacuum control valve of the vacuum vane machine on the vacuum leaf filter is docked with the waste acid washing vacuum air-lock valve of the low-iron waste acid washing tank, open these two valves in sequence to start the low-iron waste acid washing program; At the same time, open and adjust the waste acid control valve again to ensure the stability of the low-iron waste acid liquid level in the tank; When the washing waste acid volume reaches 7.5-8.5 m 3 per ton, close the vacuum control valve of the vacuum leaf filter, the waste acid washing vacuum air-lock valve and the waste acid control valve, and then lift the filter cake and drain it;

[0027] (3) Clean water washing process: Inject clean water into the clean water washing tank until the liquid level reaches 52%-60% of the tank's own volume, and then close the clean water control valve; The crane hoists the vacuum leaf filter that has been washed with low-iron waste acid and drained the filter cake in step (2) to the clean water washing tank. After the vacuum control valve of the vacuum leaf filter on the vacuum leaf filter is docked with the clean water washing vacuum air-lock valve of the clean water washing tank, open these two valves in sequence to start the clean water washing process; During this period, open and adjust the clean water control valve again to maintain the constant liquid level of the clean water in the tank; When the washing water volume reaches 9.5-10.5 m 3 per ton, close the vacuum control valve of the vacuum leaf filter, the clean water washing vacuum air-lock valve and the clean water control valve, and then lift the filter cake and drain it;

[0028] (4) Stirring and pulping process: The filter cake after being washed with clean water and drained in step (3) is hoisted together with the vacuum leaf filter to the leaf filter support frame of the horizontal pulping tank and placed stably. Then use pressure water to wash the filter cake into the horizontal pulping tank for stirring and pulping operation;

[0029] (5) Slurry transportation section: The slurry that has been evenly beaten in the horizontal beating tank in step (4) is transported to the salt treatment position in the next process through a slurry transfer pump, thus completing the entire titanium white slurry washing operation.

[0030] Further, the liquid content of the filter cake after the sheet loading operation in step (1) is 69.8% - 73.6%, and the main components of the liquid phase are H with a concentration of 290 - 310 g / L 2 SO 4 and FeSO with a concentration of 132 - 145 g / L 4 ; the liquid content of the filter cake after the low-iron waste acid washing process in step (2) is 67.9% - 69.9%, and the main components of the liquid phase become H with a concentration of 37.7 - 41.5 g / L 2 SO 4 and FeSO with a concentration of 0.028 - 0.030 g / L 4 ; the liquid content of the filter cake after the clear water washing in step (3) is 66.6% - 68.5%, and the main components of the liquid phase are H with a concentration of 0.040 - 0.044 g / L 2 SO 4 and FeSO with a concentration of 0.0009 - 0.0011 g / L 4 ; the iron content of the material obtained after flaking, stirring, and beating is approximately 0.0020 - 0.0025%.

[0031] The present invention also provides a method for preparing low-iron waste acid used in step (2) of the titanium white slurry washing process for water conservation, emission reduction, and iron reduction by adding low-iron waste acid washing in sulfuric acid process titanium white production. The steps are as follows:

[0032] S1. Mix the washing liquid in the first approximately 2 / 3 of the time during the clear water washing of the titanium white slurry in the clear water washing tank with 2 / 5 of the mother liquor from the sheet loading to make an acidic liquid containing H with a concentration of 35 g / L 2 SO 4 and FeSO with a concentration of 16 g / L 4 ;

[0033] S2. Use a ceramic tube filter to filter the acidic liquid, separating and recovering the solid titanium oxide therein;

[0034] S3. Use a nanofiltration membrane made of sulfonated polysulfone with a pore size of 1 nm to filter the acidic liquid that has been filtered and clarified by the ceramic tube filter again; obtain a low-iron waste acid liquid containing H 2 SO 4 with a concentration of 35 - 39 g / L and FeSO 4 with a concentration of 0.1 - 0.15 g / L.

[0035] The technical features and advantages of the present invention compared with the prior art include:

[0036] Increasing the use of low-iron waste acid for washing is the core innovation of the present invention. In the production process of sulfuric acid process titanium dioxide, the traditional process faces many challenges in reducing the iron content in the washing slurry and reducing the consumption of fresh water for washing. The present invention introduces the low-iron waste acid washing link and precisely breaks through these problems. Through the interaction between the low-iron waste acid and the slurry, the iron ions in the slurry are effectively displaced, thus achieving the goal of significantly reducing the iron content in the washing slurry. At the same time, in the washing process, the reasonable use of low-iron waste acid optimizes the chemical balance of the entire washing system, enabling the significant reduction of the fresh water consumption for washing while ensuring the washing effect. The fresh water consumption and sewage discharge for washing are reduced by 10 m 3 / ton respectively, and the fresh water consumption and sewage discharge of the total process are reduced by 50% respectively, fundamentally solving these two key problems that have long existed in the industry.

[0037] Secondly, the preparation method of the low-iron waste acid is to mix the washing liquid after being washed with clear water and the upper sheet mother liquor in a precise proportion and mix them evenly, and then obtain it through membrane filtration treatment. In traditional production, the washing liquid after being washed with clear water is usually all discharged to the environmental protection treatment link, which not only causes waste of water resources but also increases the pressure and cost of environmental protection treatment. However, the present invention effectively recycles part of the washing liquid. Through scientific proportioning with the upper sheet mother liquor and membrane filtration treatment, it is successfully transformed into low-iron waste acid and returned to the low-iron waste acid washing link. This way of recycling greatly reduces the amount of sewage treatment, reduces the environmental protection treatment cost, and realizes green environmental protection and resource conservation in the production process.

[0038] The two-step washing method of low-iron waste acid washing followed by clear water washing adopted by the present invention improves the traditional cumbersome washing process. In the previous process, there were multiple repeated and complex operations including flaking, stirring and pulping, bleaching, and sheeting, which not only consumed a large amount of manpower, material resources and time but also increased the equipment investment and operation energy consumption. However, the two-step washing method of the present invention omits these intermediate links and greatly simplifies the washing process. This makes the entire production process more efficient and convenient, saving more than 50% of the workload, reducing the scale of equipment and operation energy consumption by 50%; reducing the equipment investment cost, reducing the workload of the washing operation, and also significantly reducing the operation energy consumption of the washing operation, bringing considerable economic benefits and production efficiency improvement to the enterprise.

[0039] In terms of equipment selection and application, the present invention uses a vacuum leaf filter as the main washing equipment, and a crane is used as the lifting equipment to lift the vacuum leaf filter across the tank, thereby completing a series of key operations. With its unique filtering structure and working principle, the vacuum leaf filter can achieve efficient solid-liquid separation and impurity removal during processes such as slurry loading, low-iron waste acid washing, and fresh water washing. The flexible lifting function of the crane ensures the rapid and accurate transfer of the vacuum leaf filter between various operation links, guaranteeing the continuity and stability of the entire production process. This equipment combination method not only ensures the conservation and stability of the washing water consumption, but also enables the iron content of the washed slurry to always be maintained at a relatively low level, providing a solid equipment guarantee and process foundation for the production of high-quality titanium dioxide.

[0040] In summary, the titanium white slurry washing process for sulfuric acid process titanium white production with increased low-iron waste acid washing in the present invention achieves significant breakthroughs and progress in multiple aspects through technological innovation, process optimization, and reasonable equipment application. The iron content of the washed titanium white slurry is reduced from the average level of 0.0045% in the existing industry to 0.0025%, exceeding the best level in the current industry; it brings new development opportunities and solutions to the sulfuric acid process titanium dioxide production industry.

Description of the Drawings

[0041] Figure 1 It is a structural schematic diagram and process flow chart of a titanium white slurry washing device for sulfuric acid process titanium white production with increased low-iron waste acid washing described in the present invention.

[0042] The reference numerals in the figure are: crane 1, water-washing vacuum leaf filter 2, slurry loading tank 3, low-iron waste acid washing tank 4, fresh water washing tank 5, horizontal beating tank 6, slurry transfer pump 7, vacuum leaf filter frame 2.1, vacuum leaf 2.2, vacuum connection pipe of vacuum leaf filter 2.3, vacuum storage tank 2.4, vacuum control valve of vacuum leaf filter 2.5, slurry transfer pipe 3.1, slurry control valve 3.2, vacuum connection pipe for slurry loading 3.3, vacuum air-lock valve for slurry loading 3.4, waste acid transfer pipe 4.1, waste acid control valve 4.2, vacuum connection pipe for waste acid washing 4.3, vacuum air-lock valve for waste acid washing 4.4, fresh water transfer pipe 5.1, fresh water control valve 5.2, vacuum connection pipe for fresh water washing 5.3, vacuum air-lock valve for fresh water washing 5.4, leaf filter support frame 6.1.

Detailed Embodiment

[0043] The features and technical advantages of the present invention have been broadly described above so as to better understand the detailed description of the present invention. Other features and advantages of the present invention will be described hereinafter. Those skilled in the art should understand that the disclosed concepts and specific embodiments can be easily used as a basis to modify or design other structures to achieve the same purpose of the present invention. Those skilled in the art should also recognize that such equivalent configurations do not deviate from the spirit and scope of the present invention. The novel features considered to be characteristic of the present invention, its structural and operational methods, as well as further purposes and advantages, will be better understood from the following description in conjunction with the accompanying drawings. However, it should be deeply understood that each feature provided is only for description and illustration, and is not intended to limit the definition of the present invention.

[0044] With reference to the following drawings, non-limiting and non-exclusive embodiments will be described, in which the same reference numerals represent the same components, unless otherwise specifically stated.

[0045] In the present invention, a titanium white slurry washing device for water saving, emission reduction and iron reduction by increasing low-iron waste acid washing in sulfuric acid process titanium white production includes a crane 1, a water washing vacuum leaf filter 2, a slurry loading tank 3, a low-iron waste acid washing tank 4, a fresh water washing tank 5, a horizontal beating tank 6, and a slurry transfer pump 7; the structural schematic and process flow diagram of the device are shown in Figure 1 ;

[0046] Wherein the crane 1 is installed on the rail at a height of about 9 - 11 m from the reference ground of the factory building; the water washing vacuum leaf filter 2 is lifted by the crane and moves on facilities such as the slurry loading tank 3, the low-iron waste acid washing tank 4, the fresh water washing tank 5, and the horizontal beating tank 6 to complete its operations at different stages; the slurry loading tank 3, the low-iron waste acid washing tank 4, the fresh water washing tank 5, and the horizontal beating tank 6 are installed on the reference ground of the factory building and arranged in the same direction in sequence; the slurry transfer pump 7 is also installed on the reference ground of the factory building near the discharge end of the horizontal beating tank, and its inlet is connected to the lowest point of the horizontal beating tank.

[0047] The function of the crane 1: The crane 1 is responsible for lifting the vacuum leaf filter 2. The vacuum leaf filter 2 is lifted to the slurry loading tank 3 for loading operation. During this process, when the filter cake thickness reaches 37 - 43 mm, the loading stops and it is lifted to be drained. Then, the crane 1 lifts the drained vacuum leaf filter 2 to the low-iron waste acid washing tank 4 for washing work. After the washing meets the requirements, it is lifted again to be drained. Subsequently, it is lifted to the fresh water washing tank 5 for continuous washing, and is also lifted to be drained after reaching the washing standard. After that, the crane 1 lifts the vacuum leaf filter 2 above the horizontal beating tank 6 for peeling, stirring and beating operations. Finally, the uniformly stirred and beaten slurry is transported by the slurry transfer pump 7 to the next station for treatment, and so on in a cycle to complete the washing operation of the titanium white slurry.

[0048] The components of the vacuum leaf filter 2 include a vacuum leaf filter frame 2.1, vacuum leaves 2.2, a vacuum connection pipe 2.3 of the vacuum leaf filter, a vacuum storage tank 2.4, a vacuum control valve 2.5 of the vacuum leaf filter, etc.; the vacuum leaves 2.2 are suspended below the vacuum leaf filter frame 2.1. The vacuum connection pipe 2.3 of the vacuum leaf filter is installed above the vacuum leaf filter frame 2.1, the vacuum storage tank 2.4 is installed on the upper right side of the vacuum leaf filter frame 2.1, and the vacuum control valve 2.5 of the vacuum leaf filter is installed at the front end of the vacuum leaf filter frame 2.1.

[0049] Functions of each component of the vacuum leaf filter 2: The vacuum leaf filter frame 2.1 serves to connect, fix, and support the remaining components that make up the vacuum leaf filter. The vacuum leaves 2.2 are used for related filtration operations. One end of the vacuum connection pipe 2.3 of the vacuum leaf filter is connected to the flange of the vacuum control valve 2.5 of the vacuum leaf filter, and the other end is connected to the end of the vacuum storage tank 2.4, serving to transmit vacuum, etc. The vacuum storage tank 2.4 provides a certain gas storage function for the system. The vacuum control valve 2.5 of the vacuum leaf filter is used to control related vacuum processes. The overall vacuum leaf filter formed by combining these components can perform operations such as sheet loading of the slurry, low-iron waste acid washing, and fresh water washing on the slurry, and after the slurry becomes a qualified product, it is sent to the next process through sheet stripping and beating.

[0050] The components of the slurry sheet loading tank 3 include a slurry delivery pipe 3.1, a slurry control valve 3.2, a slurry sheet loading vacuum connection pipe 3.3, and a slurry sheet loading vacuum air lock valve 3.4, etc.; among them, the slurry delivery pipe 3.1 is arranged at the rear end of the slurry sheet loading tank 3, and the slurry control valve 3.2 is installed at a position on the slurry delivery pipe 3.1 close to the rear end of the slurry sheet loading tank 3. The slurry sheet loading vacuum connection pipe 3.3 is laid at the lower front end of the slurry sheet loading tank 3, and the slurry sheet loading vacuum air lock valve 3.4 is connected to the slurry sheet loading vacuum connection pipe 3.3 and fixed at the middle front end of the slurry sheet loading tank 3.

[0051] Functions of each component of the slurry sheet loading tank 3: The slurry delivery pipe 3.1 is used to transport the hydrolyzed slurry to the slurry sheet loading tank 3. The slurry control valve 3.2 can control the inflow of the hydrolyzed slurry. When it is opened, the hydrolyzed slurry can enter the slurry sheet loading tank 3, and when it is closed after reaching the required liquid level, the feeding can be stopped. The slurry sheet loading vacuum connection pipe 3.3 and the slurry sheet loading vacuum air lock valve 3.4 are used in combination. After the vacuum control valve 2.5 on the vacuum leaf filter 2 in the water washing process is docked with it, by sequentially opening the relevant valves, the slurry sheet loading operation can start. During the entire sheet loading process, by opening and adjusting the slurry control valve 3.2 again, the liquid level of the slurry in the tank can be kept constant, ensuring the smooth progress of the sheet loading operation until the sheet loading reaches a thickness of 37 - 43 mm, then closing the relevant valves and lifting it to drain, thus completing the sheet loading operation.

[0052] The components of the low-iron waste acid washing tank 4 include a waste acid delivery pipe 4.1, a waste acid control valve 4.2, a waste acid washing vacuum connection pipe 4.3, a waste acid washing vacuum air-lock valve 4.4, etc.; the waste acid delivery pipe 4.1 is located at the rear end of the low-iron waste acid washing tank 4, and the waste acid control valve 4.2 is installed at a position on the waste acid delivery pipe 4.1 close to the rear end of the low-iron waste acid washing tank 4. The waste acid washing vacuum connection pipe 4.3 is arranged at the lower part of the front end of the low-iron waste acid washing tank 4, and the waste acid washing vacuum air-lock valve 4.4 is connected to the waste acid washing vacuum connection pipe 4.3 and fixed at the middle part of the front end of the low-iron waste acid washing tank 4.

[0053] Functions of each component of the low-iron waste acid washing tank 4: The waste acid delivery pipe 4.1 is used to transport low-iron waste acid to the washing tank 4. The waste acid control valve 4.2 controls the inflow of low-iron waste acid. When opened, low-iron waste acid can enter the washing tank and is closed after reaching the required liquid level to stop the acid inflow. The waste acid washing vacuum connection pipe 4.3 and the waste acid washing vacuum air-lock valve 4.4 cooperate with the corresponding components on the water washing vacuum leaf filter 2. After docking and opening the relevant valves, the low-iron waste acid washing process is started. During the washing process, opening and adjusting the waste acid control valve 4.2 again can keep the liquid level of low-iron waste acid in the tank constant, ensuring the washing effect. After the washing reaches the requirements, the relevant valves are closed and lifted to drain, completing the low-iron waste acid washing operation.

[0054] The components of the clean water washing tank 5 include a clean water delivery pipe 5.1, a clean water control valve 5.2, a clean water washing vacuum connection pipe 5.3, a clean water washing vacuum air-lock valve 5.4, etc.; among them, the clean water delivery pipe 5.1 is located at the rear end of the clean water washing tank 5, and the clean water control valve 5.2 is installed at a position on the clean water delivery pipe 5.1 close to the rear end of the clean water washing tank 5. The clean water washing vacuum connection pipe 5.3 is arranged at the lower part of the front end of the clean water washing tank 5, and the clean water washing vacuum air-lock valve 5.4 is connected to the clean water washing vacuum connection pipe 5.3 and fixed at the middle part of the front end of the clean water washing tank 5.

[0055] Functions of each component of the clean water washing tank 5: The clean water delivery pipe 5.1 is used to transport clean water to the clean water washing tank 5. The clean water control valve 5.2 can control the inflow of clean water. When opened, clean water can enter the clean water washing tank 5 and is closed after reaching the required liquid level to stop the water inflow. The clean water washing vacuum connection pipe 5.3 and the clean water washing vacuum air-lock valve 5.4 cooperate with the corresponding components on the water washing vacuum leaf filter 2. After docking and opening the relevant valves, the clean water washing process is started. During the washing process, opening and adjusting the clean water control valve 5.2 again can keep the liquid level of clean water in the tank constant, ensuring the washing effect. After the washing reaches the requirements, the relevant valves are closed and lifted to drain, completing the clean water washing operation.

[0056] The components of the horizontal beating tank 6 include a leaf filter support frame 6.1; the leaf filter support frame 6.1 is installed above the horizontal beating tank 6, and the support top beam of the leaf filter support frame 6.1 is 1.8 - 2.0 m higher than the surface of the horizontal beating tank, and its four support legs are supported on the reference ground.

[0057] Functions of the horizontal beating tank 6 and its components: The leaf filter support frame 6.1 is used to place the filter cake that has been washed with clear water and drained and is transported by the vacuum leaf filter 2, providing a stable placement platform for subsequent operations. During the flaking, stirring, and beating operations, first place the filter cake steadily on the leaf filter support frame 6.1, then use pressurized water to wash the filter cake into the horizontal beating tank 6, and then the horizontal beating tank 6 stirs and beats the filter cake that has fallen into it, thus completing the flaking, stirring, and beating operations, making the material mix evenly and facilitating subsequent processing.

[0058] The slurry transfer pump 7 is a plastic-lined wear-resistant and corrosion-resistant slurry pump, installed on the reference ground and near the front end of the horizontal beating tank 6. Its feed inlet is connected to the lowest point of the horizontal beating tank 6, and the upper culvert transfer pipe leads to the salt treatment tank.

[0059] Function of the slurry transfer pump 7: The slurry transfer pump 7 is mainly used to transfer the slurry. In the final stage of the titanium white slurry washing operation, the slurry that has been evenly stirred and has good fluidity in the horizontal beating tank 6 is sucked in from its feed inlet, and then pumped to the salt treatment station, thus completing the material transfer work from the horizontal beating tank to the salt treatment station in the entire titanium white slurry washing process, ensuring the continuity of the production process.

[0060] A titanium white slurry washing process for sulfuric acid process titanium white production that increases water conservation, emission reduction, and iron reduction by washing with low-iron waste acid specifically includes the following steps:

[0061] (I) Slurry sheet loading operation: The titanium white slurry to be washed is injected into the slurry sheet loading tank 3. When the liquid level reaches 52% - 60% of the self-volume of the tank, close the slurry control valve 3.2; the crane 1 hoists the vacuum leaf filter 2 to the slurry sheet loading tank 3. After the vacuum control valve 2.5 on the vacuum leaf filter 2 is accurately docked with the slurry sheet loading vacuum air-lock valve 3.4 of the slurry sheet loading tank 3, open these two valves in sequence to start the sheet loading operation. During the sheet loading operation, open and adjust the slurry control valve 3.2 again to ensure that the slurry liquid level in the tank always remains constant; when the filter cake thickness reaches 37 - 43 mm, complete the sheet loading operation, close the vacuum control valve 2.5 on the vacuum leaf filter, the slurry sheet loading vacuum air-lock valve 3.4, and the slurry control valve 3.2 in sequence, and then lift the filter cake to drain it.

[0062] (II) Low-iron waste acid washing step: Put the one containing H 2 SO 4 with a concentration of 35 - 39 g / L and containing FeSO 4Low-iron waste acid with a concentration of 0.1 - 0.15 g / L is injected into the low-iron waste acid washing tank 4 until the liquid level reaches 52 - 60% of the tank's own volume, and then the waste acid control valve 4.2 is closed; the crane 1 hoists the vacuum leaf filter 2 that has completed the sheet loading operation in step (i) to the low-iron waste acid washing tank 4. After the vacuum control valve 2.5 of the vacuum vane machine on the vacuum leaf filter 2 is docked with the waste acid washing vacuum lock valve 4.4 of the low-iron waste acid washing tank 4, these two valves are opened in sequence to start the low-iron waste acid washing procedure; meanwhile, the waste acid control valve 4.2 is opened and adjusted again to ensure the stability of the low-iron waste acid liquid level in the tank; when the amount of washing waste acid reaches 7.5 - 8.5 m per ton 3 After that, the vacuum control valve 2.5 of the vacuum leaf filter, the waste acid washing vacuum lock valve 4.4, and the waste acid control valve 5.2 are closed, and then the filter cake is hoisted and drained;

[0063] (iii) Fresh water washing process: Fresh water is injected into the fresh water washing tank 5 until the liquid level reaches 52% - 60% of the tank's own volume, and then the fresh water control valve 5.2 is closed; the crane 1 hoists the vacuum leaf filter 2 that has been washed with low-iron waste acid and drained of the filter cake in step (ii) to the fresh water washing tank 5. After the vacuum control valve 2.5 of the vacuum leaf filter on the vacuum leaf filter 2 is docked with the fresh water washing vacuum lock valve 5.4 of the fresh water washing tank 5, these two valves are opened in sequence to start the fresh water washing process; during this period, the fresh water control valve 5.2 is opened and adjusted again to maintain the constant liquid level of the fresh water in the tank; when the amount of washing water reaches 9.5 - 10.5 m per ton 3 After that, the vacuum control valve 2.5 of the vacuum leaf filter, the fresh water washing vacuum lock valve 5.4, and the fresh water control valve 5.2 are closed, and then the filter cake is hoisted and drained;

[0064] (iv) Stirring and pulping process: The filter cake after being washed with fresh water and drained in step (iii) is hoisted together with the vacuum leaf filter 2 to the leaf filter support frame 6.1 of the horizontal pulping tank 6 and placed stably, and then the filter cake is washed into the horizontal pulping tank 6 with pressure water for stirring and pulping operation;

[0065] (v) Pulp transportation link: The pulp that has been evenly stirred and pulped in the horizontal pulping tank 6 in step (iv) is transported to the salt treatment post of the next process through the pulp transportation pump 7, and thus the entire titanium white pulp washing operation is completed.

[0066] The liquid content of the filter cake after completing the sheet loading operation in step (i) is 69.8% - 73.6%, and the main components of the liquid phase are H with a concentration of 290 - 310 g / L 2 SO 4 and FeSO with a concentration of 132 - 145 g / L 4 ; the liquid content of the filter cake after the low-iron waste acid washing procedure in step (ii) is 67.9% - 69.9%, and the main components of the liquid phase become H with a concentration of 37.7 - 41.5 g / L2 SO 4 、 and FeSO₄ with a concentration of 0.028 - 0.030 g / L 4 ; the liquid content of the filter cake after being washed with clear water in step (three) is 66.6% - 68.5%, and the main components of the liquid phase are H₂SO₄ with a concentration of 0.040 - 0.044 g / L 2 SO 4 , and FeSO₄ with a concentration of 0.0009 - 0.0011 g / L 4 ; the iron content of the material obtained after flaking, stirring and pulping is about 0.0020 - 0.0025%.

[0067] The preparation method of the low - iron waste acid used in step (two) of the titanium white slurry washing process is as follows:

[0068] S1. Mix the washing liquid in the first about 2 / 3 of the time when the titanium white slurry is washed with clear water in the clear water washing tank 5 with 2 / 5 of the mother liquor on the sheet - forming pool 3 that is filtered and separated, so as to mix them into an acidic liquid containing H₂SO₄ with a concentration of 35 g / L 2 SO 4 and FeSO₄ with a concentration of 16 g / L 4 ;

[0069] S2. Use a ceramic tube filter to filter the acidic liquid, and separate and recover the solid titanium oxide in it;

[0070] S3. Use a nanofiltration membrane made of sulfonated polysulfone with a pore size of 1 nm to filter the acidic liquid that has been filtered and clarified by the ceramic tube filter again; obtain a low - iron waste acid liquid containing H₂SO₄ of 35 - 39 g / L and FeSO₄ of 0.1 - 0.15 g / L 2 SO 4 ; 4 ;

[0071] To make the disclosure of the present invention more sufficient, it is further illustrated by more specific embodiments below.

[0072] Example 1

[0073] A titanium white slurry washing process for increasing water conservation, emission reduction and iron reduction by using low - iron waste acid washing in sulfuric acid - process titanium white production specifically includes the following steps:

[0074] (1) Slurry sheet - forming operation: The TiO₂ slurry to be washed with a concentration of 186 g / L 2The slurry is injected into the upper slurry tank 3. When the liquid level reaches 55% of the tank's own volume, the slurry control valve 3.2 is closed. The crane 1 hoists the vacuum leaf filter 2 to the upper slurry tank 3. After the vacuum control valve 2.5 of the vacuum leaf filter on the vacuum leaf filter 2 is accurately docked with the slurry loading vacuum air-lock valve 3.4 of the upper slurry tank 3, these two valves are opened in sequence to start the loading operation. During the loading operation, the slurry control valve 3.2 is opened again and adjusted to ensure that the slurry liquid level in the tank remains constant all the time. The loading operation lasts for 50 minutes. When the filter cake thickness reaches 40 mm, the loading operation is completed. The vacuum control valve 2.5 of the vacuum leaf filter, the slurry loading vacuum air-lock valve 3.4 and the slurry control valve 3.2 are closed in sequence. Then the filter cake is hoisted and drained;

[0075] (2) Low-iron waste acid washing step: Inject the low-iron waste acid with H 2 SO 4 content of 38 g / L and FeSO 4 content of 0.15 g / L into the low-iron waste acid washing tank 4 until the liquid level reaches 54% of the tank's own volume, and then close the waste acid control valve 4.2. The crane 1 hoists the vacuum leaf filter 2 that has completed the loading operation in step (1) to the low-iron waste acid washing tank 4. After the vacuum control valve 2.5 of the vacuum vane machine on the vacuum leaf filter 2 is docked with the waste acid washing vacuum air-lock valve 4.4 of the low-iron waste acid washing tank 4, these two valves are opened in sequence to start the low-iron waste acid washing program. At the same time, the waste acid control valve 4.2 is opened again and adjusted to ensure the stability of the low-iron waste acid liquid level in the tank. The low-iron waste acid washing program lasts for 50 minutes. When the washing waste acid volume reaches 8.5 m 3 per ton, the vacuum control valve 2.5 of the vacuum leaf filter, the waste acid washing vacuum air-lock valve 4.4 and the waste acid control valve 5.2 are closed. Then the filter cake is hoisted and drained;

[0076] (3) Clean water washing process: Inject clean water into the clean water washing tank 5 until the liquid level reaches 58% of the tank's own volume, and then close the clean water control valve 5.2. The crane 1 hoists the vacuum leaf filter 2 that has been washed with low-iron waste acid and drained the filter cake in step (2) to the clean water washing tank 5. After the vacuum control valve 2.5 of the vacuum leaf filter on the vacuum leaf filter 2 is docked with the clean water washing vacuum air-lock valve 5.4 of the clean water washing tank 5, these two valves are opened in sequence to start the clean water washing process. During this period, the clean water control valve 5.2 is opened again and adjusted to maintain the constant liquid level of the clean water in the tank. The clean water washing process lasts for 40 minutes. When the washing water volume reaches 10 m 3 per ton, the vacuum control valve 2.5 of the vacuum leaf filter, the clean water washing vacuum air-lock valve 5.4 and the clean water control valve 5.2 are closed. Then the filter cake is hoisted and drained. After the clean water washing, the iron content in the slurry is measured to be 0.0022%; The TiO of a single leaf filter 2The processing capacity is 1.15 tons, the operating cycle of the leaf filter is 2.33 h, and the processing capacity of each single leaf filter per hour is 0.494 t; the total consumption of fresh water is 10 m 3 / ton TiO 2 ;

[0077] (4) Stirring and pulping process: The filter cake after being washed with fresh water and drained in step (3) is lifted together with the vacuum leaf filter 2 to the leaf filter support frame 6.1 of the horizontal pulping tank 6 and placed stably. Then, the filter cake is flushed into the horizontal pulping tank 6 with pressure water for stirring and pulping operation;

[0078] (5) Pulp transportation link: The pulp that has been evenly stirred and pulped in the horizontal pulping tank 6 in step (4) is transported to the salt treatment post in the next process by the pulp transportation pump 7, and thus the entire titanium white pulp washing operation is completed.

[0079] Example 2

[0080] It is basically the same as Example 1, except that the upper slice operation lasts for 54 min, the thickness of the upper slice is 43 mm, the low-iron waste acid washing procedure lasts for 52 min, and the consumption of low-iron waste acid is 8.2 m 3 / ton TiO 2 , the fresh water washing process lasts for 42 min, and the consumption of fresh water is 10 m 3 / ton TiO 2 , and the iron content in the pulp measured after fresh water washing is 0.0025%; the TiO 2 processing capacity of each single leaf filter is 1.236 tons, the operating cycle of the leaf filter is 2.467 h, and the processing capacity of each single leaf filter per hour is 0.501 t; the total consumption of fresh water is 10 m 3 / ton TiO 2 .

[0081] Example 3

[0082] It is basically the same as Example 1, except that the upper slice operation lasts for 47 min, the thickness of the upper slice is 37 mm, the low-iron waste acid washing procedure lasts for 48 min, and the consumption of low-iron waste acid is 8.0 m 3 / ton TiO 2 , the fresh water washing process lasts for 38 min, and the consumption of fresh water is 10 m 3 / ton TiO 2 , and the iron content in the pulp measured after fresh water washing is 0.0021%; the TiO 2 processing capacity of each single leaf filter is 1.064 tons, the operating cycle of the leaf filter is 2.217 h, and the processing capacity of each single leaf filter per hour is 0.408 t; the total consumption of fresh water is 10 m 3 / ton TiO 2 .

[0083] Comparative Example 1

[0084] The titanium white slurry was filtered and washed by using a traditional leaf filter device with a secondary beating, bleaching and washing method. The TiO 2 slurry concentration was 186 g / L, the first sheet loading time was 50 min, the sheet loading thickness was 40 mm, the first washing time with clear water was 40 min, and the consumption of clear water was 10 m 3 / ton TiO 2 . After beating, heating and bleaching for 90 min, the second sheet loading time was 35 min, the sheet loading thickness was 40 mm, the second washing time with clear water was 36 min, and the consumption of clear water was 10 m 3 / ton TiO 2 . After the second washing with clear water, the iron content in the slurry was measured to be 0.0043%; the TiO 2 processing capacity of a single leaf filter was 1.15 tons, the operating cycle of the leaf filter was 2.68 h, and the hourly processing capacity of a single leaf filter was 0.429 t; the total consumption of clear water was 20 m 3 / ton TiO 2 .

[0085] The comparison results of the data of Examples 1-3 and Comparative Example 1 are shown in Table 1 below.

[0086] Table 1 Comparison of data of Examples and Comparative Examples

[0087]

[0088]

[0089] From the comparison of the data of the examples and the comparative examples, it can be seen that the titanium white slurry washing process of the sulfuric acid process titanium white production of the present invention, which increases the water-saving, emission-reduction and iron-reducing by washing with low-iron waste acid, has the following significant advantages compared with the traditional leaf filter device using the secondary beating, bleaching and washing method:

[0090] 1. Improvement in processing capacity: In terms of the hourly processing capacity, the process of the present invention shows better overall performance. In Examples 1-3, the hourly processing capacities of a single leaf filter are 0.494 t, 0.501 t, and 0.480 t respectively, all higher than 0.429 t of Comparative Example 1. Among them, the improvement ratio of Example 1 is about 15.15%, the improvement ratio of Example 2 is about 16.78%, and the improvement ratio of Example 3 is about 11.89%. This shows that the process of the present invention can improve production efficiency, increase production capacity, and bring higher economic benefits to enterprises.

[0091] 2. Remarkable water-saving effect: The consumption of clear water per ton of TiO 2 in the examples is 10 m 3 , compared with 20 m 3, with a reduction ratio of up to 50%. The fresh water consumption per ton of TiO 2 has been significantly reduced, only being half of that of the traditional process, which is of great significance for the current situation of water resource shortage and for enterprises to reduce production costs, meeting the requirements of green environmental protection and sustainable development.

[0092] 3. Improvement in product quality: The Fe n+ content in the filter cake has been significantly reduced. The Fe n+ contents in the filter cakes of Examples 1 - 3 are 0.0022%, 0.0025%, and 0.0021% respectively, far lower than 0.0043% of Comparative Example 1. The reduction ratio of Example 1 is about 48.84%, that of Example 2 is about 41.86%, and that of Example 3 is about 51.16%, making the quality of titanium dioxide far exceed the industry average level and greatly enhancing the competitiveness of the product in the market.

[0093] 4. Simplification of the process: The present invention adopts a one - step two - stage washing method, omitting cumbersome operations such as flaking, stirring and beating into pulp, bleaching, and secondary flaking in the traditional process, simplifying the washing process, reducing equipment investment costs, the workload of washing operations, and operating energy consumption, and further reducing production costs.

[0094] In summary, the titanium white slurry washing process of the present invention shows obvious advantages in many aspects and has good application prospects and popularization value.

[0095] Those skilled in the art will recognize that numerous modifications to the above description are possible, so the examples are only used to describe one or more specific embodiments.

[0096] Although the present invention has been described in detail along with its advantages, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the present invention. In addition, the scope of application of the present invention is not limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, methods, and steps described in the specification. From the disclosure of the present invention, those skilled in the art will easily utilize existing or later - developed processes, machines, manufactures, compositions of matter, methods, or steps that substantially perform the same functions or achieve the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to cover these processes, machines, manufactures, compositions of matter, methods, or steps.

Claims

1. A titanium dioxide slurry washing device for adding low-iron waste acid washing to save water, reduce emissions and reduce iron in the production of titanium dioxide by sulfuric acid process, characterized in that: Including crane, water-washing vacuum leaf filter, slurry loading pool, low-iron waste acid washing pool, clean water washing pool, horizontal beating tank, slurry delivery pump; The crane is installed on the rails at a height of 9-11m from the reference ground; the water-washed vacuum leaf filter is hoisted on the crane; the slurry loading pool, low-iron waste acid washing pool, clean water washing pool and horizontal pulping tank are installed on the reference ground and arranged in sequence in the same direction; the slurry delivery pump is installed on the reference ground close to the discharge end of the horizontal pulping tank, and its feed port is connected to the lowest point of the horizontal pulping tank.

2. The titanium dioxide slurry washing device for saving water, reducing emissions and reducing iron content in the production of titanium dioxide by sulfuric acid process according to claim 1 is characterized in that: The components of the vacuum leaf filter include a vacuum leaf filter frame, vacuum blades, a vacuum connecting pipe of the vacuum leaf filter, a vacuum gas storage tank, and a vacuum control valve of the vacuum leaf filter; the vacuum blades are hung at the lower part of the vacuum leaf filter frame; the vacuum connecting pipe of the vacuum leaf filter is installed above the vacuum leaf filter frame, the vacuum gas storage tank is installed on the upper right side of the vacuum leaf filter frame, and the vacuum control valve of the vacuum leaf filter is installed at the front end of the vacuum leaf filter frame.

3. The titanium dioxide slurry washing device for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 1, characterized in that: The components of the slurry upper sheet pool include a slurry conveying pipe, a slurry control valve, a slurry upper sheet vacuum connecting pipe and a slurry upper sheet vacuum air locking valve; wherein the slurry conveying pipe is arranged at the rear end of the slurry upper sheet pool, and the slurry control valve is installed at the position of the slurry conveying pipe close to the rear end of the slurry upper sheet pool; the slurry upper sheet vacuum connecting pipe is arranged at the lower front end of the slurry upper sheet pool, and the slurry upper sheet vacuum air locking valve is connected to the slurry upper sheet vacuum connecting pipe and fixed in the middle of the front end of the slurry upper sheet pool.

4. The titanium dioxide slurry washing device for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 1, characterized in that: The components of the low-iron waste acid washing tank include a waste acid delivery pipe, a waste acid control valve, a waste acid washing vacuum connecting pipe and a waste acid washing vacuum air lock valve; the waste acid delivery pipe is located at the rear end of the low-iron waste acid washing tank, and the waste acid control valve is installed at a position of the waste acid delivery pipe close to the rear end of the low-iron waste acid washing tank; the waste acid washing vacuum connecting pipe is arranged at the lower front end of the low-iron waste acid washing tank, and the waste acid washing vacuum air lock valve is connected to the waste acid washing vacuum connecting pipe and fixed at the middle front end of the low-iron waste acid washing tank.

5. The titanium dioxide slurry washing device for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 1, characterized in that: The components of the clean water washing tank include a clean water delivery pipe, a clean water control valve, a clean water washing vacuum connecting pipe and a clean water washing vacuum air lock valve; wherein the clean water delivery pipe is located at the rear end of the clean water washing tank, and the clean water control valve is installed at a position of the clean water delivery pipe close to the rear end of the clean water washing tank; the clean water washing vacuum connecting pipe is arranged at the lower front end of the clean water washing tank, and the clean water washing vacuum air lock valve is connected to the clean water washing vacuum connecting pipe and fixed at the middle front end of the clean water washing tank.

6. The titanium dioxide slurry washing device for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 1, characterized in that: The components of the horizontal pulping trough include a leaf filter support frame; the leaf filter support frame is installed above the horizontal pulping trough, the supporting top beam of the leaf filter support frame is 1.8-2.0m higher than the horizontal pulping trough surface, and its four supporting legs are supported on the reference ground.

7. The titanium dioxide slurry washing device for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 1, characterized in that: The slurry delivery pump is a plastic-lined wear-resistant and corrosion-resistant slurry pump, which is installed on the reference ground and close to the front end of the horizontal beating tank. Its feed inlet is connected to the lowest point of the horizontal beating tank, and the upper culvert delivery pipe leads to the salt treatment tank.

8. A titanium dioxide slurry washing process using a titanium dioxide slurry washing device for water saving, emission reduction and iron reduction in the production of titanium dioxide by sulfuric acid process according to claims 1-7, characterized in that: The specific steps include: (I) Slurry loading operation: The titanium dioxide slurry to be washed is injected into the slurry loading pool. When the liquid level reaches 52%-60% of the pool's own volume, the slurry control valve is closed; the vacuum leaf filter is hoisted to the slurry loading pool by a crane. After the vacuum control valve of the vacuum leaf filter on the vacuum leaf filter is accurately connected with the slurry loading vacuum air lock valve of the slurry loading pool, the two valves are opened in sequence to start the loading operation. During the loading operation, the slurry control valve is opened and adjusted again to ensure that the slurry liquid level in the pool remains constant; when the filter cake thickness reaches 37-43mm, the loading operation is completed, and the vacuum control valve of the vacuum leaf filter, the slurry loading vacuum air lock valve and the slurry control valve are closed in sequence, and then the filter cake is hoisted and drained; (ii) Low iron waste acid washing step: inject low iron waste acid containing 35-39 g / L H2SO4 and 0.1-0.15 g / L FeSO4 into the low iron waste acid washing tank until the liquid level reaches 52-60% of the tank volume, and then close the waste acid control valve; hoist the vacuum leaf filter that has completed the loading operation in step (i) to the low iron waste acid washing tank by a crane, and after the vacuum control valve of the vacuum leaf filter on the vacuum leaf filter is connected with the waste acid washing vacuum air lock valve of the low iron waste acid washing tank, open the two valves in turn to start the low iron waste acid washing program; at the same time, open and adjust the waste acid control valve again to ensure that the low iron waste acid liquid level in the tank is stable; when the amount of washing waste acid reaches 7.5-8.5 m3 / ton 3 Finally, close the vacuum control valve of the vacuum leaf filter, the vacuum air lock valve of the waste acid washing and the waste acid control valve, and then lift the filter cake and drain it; (III) Clean water washing process: inject clean water into the clean water washing tank until the liquid level reaches 52%-60% of the tank's own volume, then close the clean water control valve; hoist the vacuum leaf filter that has been washed with low-iron waste acid and the filter cake drained in step (II) to the clean water washing tank by a crane, and after the vacuum control valve of the vacuum leaf filter on the vacuum leaf filter is connected with the clean water washing vacuum air lock valve of the clean water washing tank, open these two valves in turn to start the clean water washing process; during this period, open and adjust the clean water control valve again to maintain a constant clean water level in the tank; when the washing water volume reaches 9.5-10.5m3 / ton 3 Finally, close the vacuum control valve of the vacuum leaf filter, the clean water washing vacuum air lock valve and the clean water control valve, and then hang up the filter cake and drain it; (IV) Mixing and beating process: The filter cake after being washed and drained by clean water in step (III) is hoisted together with the vacuum leaf filter to the leaf filter support frame of the horizontal beating tank and placed stably, and then the filter cake is washed into the horizontal beating tank by pressurized water for mixing and beating operation; (V) Slurry transportation: The slurry is stirred and evenly beaten in the horizontal beating tank in step (IV), and then transported to the salt treatment station of the next process through a slurry transportation pump, thus completing the entire titanium dioxide slurry washing operation.

9. The titanium dioxide slurry washing process for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 8, characterized in that: The liquid content of the filter cake after the sheeting operation in step (i) is 69.8%-73.6%, and the main components of the liquid phase are H2SO4 with a concentration of 290-310g / L and FeSO4 with a concentration of 132-145g / L; the liquid content of the filter cake after the low-iron waste acid washing procedure in step (ii) is 67.9%-69.9%, and the main component of the liquid phase becomes H2SO4 with a concentration of 37.7-41.5g / L , FeSO4 with a concentration of 0.028-0.030 g / L; the liquid content of the filter cake after washing with clean water in step (iii) is 66.6%-68.5%, and the main components of the liquid phase are H2SO4 with a concentration of 0.040-0.044 g / L and FeSO4 with a concentration of 0.0009-0.0011 g / L; the iron content of the material obtained after peeling, stirring and beating is 0.0020-0.0025%.

10. The titanium dioxide slurry washing process for adding low-iron waste acid washing to save water, reduce emissions and reduce iron content in the production of titanium dioxide by sulfuric acid process according to claim 8, characterized in that: The preparation method of the low-iron waste acid used in the step (ii) comprises the following steps: S1. The washing liquid produced by washing the titanium dioxide slurry with clean water in the clean water washing tank for the first 2 / 3 of the time is blended with 2 / 5 of the upper mother liquor separated by filtration in the upper slurry pool to mix it into an acidic liquid containing 35g / L H2SO4 and 16g / L FeSO4; S2. filtering the acidic liquid using a ceramic tubular filter to separate and recover the solid titanium oxide; S3. A nanofiltration membrane made of sulfonated polysulfone and having a pore size of 1 nm is used to filter the acidic liquid clarified by the ceramic tubular filter again; a low-iron waste acid liquid containing 35-39 g / L of H2SO4 and 0.1-0.15 g / L of FeSO4 is obtained.

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