Oxalate double decomposition precipitation impurity removal device

Abstract

The utility model relates to the technical field of aluminum production, and provides an oxalate double-decomposition precipitation impurity removal device which comprises a seed crystal tank, a washing vertical disc leading to the seed crystal tank and a causticization separation precipitation tank respectively, the causticization separation precipitation tank leading to an ash melting tank, the ash melting tank leading to a lime milk introduction pipe, and the lime milk introduction pipe leading to the washing vertical disc. And the lime milk introduction pipe leads to the causticization separation precipitation tank. According to the technical scheme, the technical problem that the quality of an aluminum oxide product produced by a causticizing process in the prior art is relatively poor is solved.

Description

Technical Field

[0001] The embodiments disclosed herein relate to the field of aluminum production technology, and more specifically, to an oxalate metathesis precipitation and impurity removal device. Background Technology

[0002] The causticization process is a key technology in alumina production, where aluminum ions are converted into aluminum hydroxide precipitate, which is then calcined to obtain alumina. Natural bauxite contains organic matter such as humic substances produced by the decomposition of plant and animal remains and microbial residues. During the mining and processing of bauxite, organic additives such as flocculants and defoamers are added. These organic substances, along with the humic components in the bauxite, are eventually converted into oxalates during the leaching and decomposition of the alumina ore. These oxalates mix into the finished alumina product, interfering with its quality. Therefore, the causticization process of alumina requires the removal of these oxalate impurities from the alumina reaction system to ensure that the product meets quality standards. Oxalate generally exists in two forms during the alumina causticization process: dissolved sodium oxalate and crystalline sodium oxalate. For dissolved sodium oxalate, since the separation of aluminum hydroxide requires filtration using a vertical disc filter, some sodium oxalate adheres to the surface of aluminum hydroxide after hot water washing and subsequently redissolves in the solution. The filtrate is then recycled into the Bayer cycle, leading to the continuous accumulation of sodium oxalate, which severely impacts the production process and product quality. During the subsequent cooling and crystallization process of aluminum hydroxide, the temperature decreases, causing sodium oxalate and aluminum hydroxide to co-crystallize and precipitate as crystalline sodium oxalate. Crystalline sodium oxalate promotes the formation of aluminum hydroxide microcrystals and can also precipitate on large aluminum hydroxide seed crystals, causing them to lose surface activity, reducing the agglomeration efficiency of aluminum hydroxide, and ultimately affecting alumina particle size control and lowering product quality. In addition, the alumina causticization process involves large equipment and strict control of multiple parameters, resulting in high equipment and material costs. In existing production, the fine seed washing liquid is often discharged into the red mud settling system for washing and settling of the red mud. However, this increases the burden on the red mud separation settling tank, leading to an increase in the water content of the red mud, which is not conducive to the control of the last discharge loss index and equipment cost of the red mud. Utility Model Content

[0003] To overcome the above-mentioned defects, the embodiments of this disclosure provide an oxalate metathesis precipitation and impurity removal device, which solves the technical problem of poor quality of alumina products produced by the causticization process in the prior art.

[0004] According to one aspect, at least one embodiment of this disclosure provides an oxalate metathesis precipitation impurity removal apparatus for removing impurities from aluminum hydroxide filtrate generated by a washing disc filtration, comprising:

[0005] Seed cell tank;

[0006] The causticizing separation precipitation tank has washing plates that are respectively connected to the seed tank and the causticizing separation precipitation tank;

[0007] Ashing tank, the causticization separation sedimentation tank leads to the ashing tank;

[0008] A lime slurry inlet pipe leads to the lime slurry inlet pipe, which in turn leads to the causticization separation sedimentation tank.

[0009] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal apparatus, which further includes:

[0010] Drainage tube;

[0011] The diversion pipe has a first branch and a second branch. The guide pipe is used to connect the washing plate and the diversion pipe. The first branch is connected to the seed tank, and the second branch leads to the causticization separation precipitation tank.

[0012] A filter press, wherein the causticizing separation sedimentation tank leads to the filter press, and the filter press leads to the seed crystal tank.

[0013] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal device, wherein the filter press has a mixture inlet and a liquid outlet, and the oxalate metathesis precipitation and impurity removal device further includes:

[0014] A feeding pump is provided, and the causticization separation sedimentation tank is connected to the mixture inlet via the feeding pump. The feeding pump is used to send the sediment in the causticization separation sedimentation tank into the mixture inlet.

[0015] An underflow pump is used, and the liquid outlet is connected to the seed tank via the underflow pump.

[0016] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal apparatus, which further includes:

[0017] An overflow tank is provided, and the causticizing separation sedimentation tank is connected to the overflow tank.

[0018] An overflow pump is provided, and the overflow trough is connected to the ash-refining tank via the overflow pump.

[0019] A mud pump is provided, and the ash-making tank is connected to the causticization separation sedimentation tank via the mud pump.

[0020] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal device, wherein the causticization separation precipitation tank has a top outlet and a bottom outlet, the top outlet leads to the overflow tank, the height of the top outlet is higher than the height of the overflow tank, and the bottom outlet leads to the mud pump.

[0021] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal apparatus, which further includes:

[0022] Cooling pipe, the cooling pipe being wound around the causticization separation sedimentation tank;

[0023] A cooler, wherein the cooling pipe leads to the cooler, the cooler is used to cool the medium inside the cooling pipe, the cooler has an inlet pipe and a return pipe, the return pipe being wound around the ash-reducing tank.

[0024] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal device, wherein the cooler is a wide-channel plate heat exchanger.

[0025] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal apparatus, which further includes:

[0026] A feeding device is provided, which leads to the lime-slaked tank and is used to add quicklime to the lime-slaked tank.

[0027] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal apparatus, which further includes:

[0028] A drain pipe is connected to the seed tank and is used for draining liquid from the seed tank.

[0029] For example, at least one embodiment of this disclosure provides an oxalate metathesis precipitation and impurity removal device, wherein both the overflow pump and the mud pump are unidirectional pumps.

[0030] The beneficial effects of the embodiments disclosed herein are as follows:

[0031] In this disclosure, a portion of the filtrate enters the seed crystal tank, while the other portion enters the causticization separation sedimentation tank for impurity removal. By adding lime milk to the causticization separation sedimentation tank, the calcium hydroxide in the lime milk undergoes a metathesis reaction with sodium oxalate and other oxalates in the filtrate. Ca2+ combines with oxalate ions to form calcium oxalate precipitate, which is then discharged from the seed crystal tank. Compared to the prior art where all the filtrate enters the red mud settling tank, this disclosure can separate impurities such as sodium oxalate in the causticization separation sedimentation tank. By reducing impurities such as sodium oxalate in the filtrate, the quality of the final alumina is improved. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments of this disclosure will be briefly introduced below. Obviously, the drawings described below are merely some exemplary embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the content of the exemplary embodiments of this disclosure and these drawings without any creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of one embodiment of the oxalate metathesis precipitation and impurity removal device disclosed herein;

[0034] In the diagram: Drainage pipe-1, Diversion pipe-2, First branch-201, Second branch-202, Seed tank-3, Causticization separation sedimentation tank-4, Ashing tank-5, Lime slurry inlet pipe-6, Filter press-7, Feed pump-8, Underflow pump-9, Overflow tank-10, Overflow pump-11, Slurry pump-12, Cooling pipe-13, Cooler-14, Inlet pipe-1401, Return pipe-1402, Feeding component-15, Drainage pipe-16. Detailed Implementation

[0035] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present disclosure and are not intended to limit the scope of the disclosure.

[0036] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0037] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0038] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0040] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] like Figure 1 As shown, it illustrates an oxalate metathesis precipitation and impurity removal device in one embodiment of the present disclosure, used to remove impurities from aluminum hydroxide filtrate generated by washing disc filtration. It includes a seed tank 3, the washing disc is connected to the seed tank 3 and the causticization separation precipitation tank 4, the causticization separation precipitation tank 4 is connected to the lime slurry tank 5, the lime slurry tank 5 is connected to the lime milk inlet pipe 6, and the lime milk inlet pipe 6 is connected to the causticization separation precipitation tank 4.

[0042] For example, such as Figure 1 As shown, a portion of the filtrate enters the seed tank 3, while the other portion enters the causticizing separation and precipitation tank 4 for impurity removal. By adding lime milk to the causticizing separation and precipitation tank 4, the calcium hydroxide in the lime milk undergoes a metathesis reaction with sodium oxalate and other oxalates in the filtrate. Ca2+ combines with oxalate ions to form calcium oxalate precipitate, which is then discharged from the seed tank 3 system. Compared to the existing technology where all the filtrate enters the red mud settling tank, this method can separate impurities such as sodium oxalate in the causticizing separation and precipitation tank 4. By reducing impurities such as sodium oxalate in the filtrate, the quality of the final alumina is improved.

[0043] After the aluminum hydroxide filtrate is causticized with lime slurry in the causticization separation sedimentation tank 4, causticized overflow is obtained. The causticized overflow enters the lime sintering tank 5, where it is mixed and stirred with quicklime to obtain lime slurry, thus continuing the lime slurry causticization cycle. Using causticized liquid to replace part of the hot water for lime digestion effectively reduces the amount of hot water used during lime sintering, while also reducing the amount of causticized slag entering the washing and settling tank, thus lowering production costs and saving related energy consumption.

[0044] The causticizing separation sedimentation tank 4 leads to the lime slurry tank 5, which in turn leads to the lime slurry inlet pipe 6. The lime slurry inlet pipe 6 then leads back to the causticizing separation sedimentation tank 4, forming a circulating impurity removal system. In the causticizing separation sedimentation tank 4, the filtrate reacts with lime slurry and other substances, removing impurities through metathesis precipitation. The resulting precipitate is separated and discharged, while the treated solution enters the lime slurry tank 5. After further treatment, it flows back to the causticizing separation sedimentation tank 4 as lime slurry, participating in the impurity removal reaction again. This recycling method not only improves the utilization rate of reagents such as lime slurry and reduces waste, but also continuously and effectively removes impurities from the filtrate, ensuring the stability of the impurity removal effect.

[0045] In some examples, a diversion pipe 1 is also included, and a branch pipe 2 has a first branch 201 and a second branch 202. The diversion pipe 1 is used to connect the washing plate and the branch pipe 2. The first branch 201 is connected to the seed tank 3, and the second branch 202 leads to the causticization separation sedimentation tank 4. The causticization separation sedimentation tank 4 leads to the filter press 7, and the filter press 7 leads to the seed tank 3.

[0046] For example, such as Figure 1 As shown, the aluminum hydroxide filtrate produced by the washing disc filtration is introduced into the branch pipe 2 through the diversion pipe 1. The first branch 201 of the branch pipe 2 is connected to the seed tank 3, and the second branch 202 leads to the causticization separation sedimentation tank 4. The causticization separation sedimentation tank 4 leads to the filter press 7, allowing the mixture that has undergone preliminary sedimentation in the causticization separation sedimentation tank 4 to enter the filter press for finer solid-liquid separation. The filter press 7 uses pressure difference to more thoroughly separate the liquid and solid in the mixture. In particular, smaller calcium oxalate impurities that are difficult to remove by simple precipitation can be effectively intercepted, further improving the purity of the filtrate. For the removal of impurities from the aluminum hydroxide filtrate, a purer filtrate provides a better raw material for the subsequent production of high-quality aluminum hydroxide products, reducing the potential impact of impurities on product quality. The filtrate after being processed by the filter press 7 enters the seed tank 3. Due to the significant reduction in impurity content in the filtrate, the presence of impurities will not affect the formation and growth of the crystals after entering the seed tank 3. The growth of seed crystals in a relatively pure environment can ensure the quality and performance of the seed crystals, thereby improving the uniformity and stability of crystal growth in the subsequent aluminum hydroxide production process, and helping to obtain aluminum hydroxide products with uniform particle size and high purity.

[0047] In some examples, the filter press 7 of the oxalate metathesis precipitation and impurity removal device has a mixture inlet 701 and a liquid outlet 702. The oxalate metathesis precipitation and impurity removal device also includes a feed pump 8. The causticization separation precipitation tank 4 is connected to the mixture inlet 701 via the feed pump 8. The feed pump 8 is used to send the precipitate in the causticization separation precipitation tank 4 into the mixture inlet 701. The liquid outlet 702 is connected to the seed tank 3 via an underflow pump 9.

[0048] For example, such as Figure 1 As shown, the feed pump 8 ensures that the precipitate in the causticization separation sedimentation tank 4 can be efficiently and stably transported to the filter press 7. The feed pump can precisely control the conveying volume and pressure according to actual production needs, ensuring that the precipitate enters the filter press 7 in a timely and sufficient manner for solid-liquid separation. During production, when the precipitate accumulates to a certain level, the feed pump 8 can quickly start and transport it out, preventing the precipitate from piling up in the causticization separation sedimentation tank 4 and ensuring the normal operation and impurity removal effect of the sedimentation tank.

[0049] The filter press 7 is connected to the seed tank 3 via an underflow pump 9. The underflow pump 9 can precisely control the transfer of the filtrate processed by the filter press 7 to the seed tank 3. It can adjust the delivery speed and flow rate of the filtrate according to the liquid level in the seed tank 3 and production needs, ensuring a stable liquid level in the seed tank 3 and providing a stable environment for seed growth. This precise control avoids excessive or insufficient filtrate transfer, improving the coordination and stability of the entire production process.

[0050] In some examples, an overflow trough 10 is also included, the causticization separation sedimentation tank 4 is connected to the overflow trough 10, the overflow trough 10 is connected to the ash-making tank 5 through the overflow pump 11, and the ash-making tank 5 is connected to the causticization separation sedimentation tank 4 through the mud pump 12.

[0051] For example, such as Figure 1 As shown, the causticization separation sedimentation tank 4 is connected to the overflow tank 10. When the liquid level in the causticization separation sedimentation tank 4 reaches a certain height, the excess liquid can flow into the overflow tank 10. This effectively controls the liquid level in the causticization separation sedimentation tank 4, avoiding problems such as affecting the sedimentation effect or causing liquid overflow due to excessive liquid level. The overflow tank 10 is connected to the lime-slaked tank 5 through the overflow pump 11, realizing the rational distribution of liquid in the system and recycling the excess liquid in the causticization separation sedimentation tank 4, avoiding waste. At the same time, the lime-slaked tank 5 is connected to the causticization separation sedimentation tank 4 through the mud pump 12. The treated liquid in the lime-slaked tank 5 is mixed with quicklime to form lime slurry, which can then flow back to the causticization separation sedimentation tank 4 to participate in the reaction, improving the overall operating efficiency of the system.

[0052] In some examples, the causticization separation sedimentation tank 4 has a top outlet 401 and a bottom outlet 402. The top outlet 401 leads to the overflow tank 10 and is higher than the overflow tank 10. The bottom outlet 402 leads to the mud pump 12.

[0053] For example, such as Figure 1As shown, the design of the top outlet 401 and bottom outlet 402 of the causticization separation sedimentation tank 4 facilitates the stratified separation of precipitate and supernatant. During sedimentation, heavier precipitates gradually settle to the bottom of the tank, while the relatively pure supernatant remains at the top. The top outlet 401 leads to the overflow tank 10 and is higher than the overflow tank 10, allowing the supernatant to flow naturally into the overflow tank 10 under gravity. This prevents the bottom precipitate from being carried out when the supernatant is extracted, ensuring that the liquid overflowing into the overflow tank 10 is relatively pure and improving the sedimentation separation effect. When treating aluminum hydroxide filtrate, impurities such as oxalate precipitate to the bottom of the tank. This stratified separation method effectively reduces the impurity content in the supernatant, providing higher-quality raw materials for subsequent impurity removal and production processes. Since the top outlet 401 is specifically for discharging the supernatant, and the bottom outlet 402 leads to the mud pump 12 for discharging the precipitate, the mixing and backflow of precipitate and supernatant are avoided. Without this clearly defined stratified outlet design, the liquid or precipitate may mix during discharge, affecting the sedimentation effect and subsequent treatment processes. This design allows the precipitate and supernatant to be discharged and treated independently, reducing the possibility of impurities re-entering the liquid and further ensuring the thoroughness of impurity removal.

[0054] In some examples, a cooling pipe 13 is also included, which is wound around the caustic separation sedimentation tank 4 and leads to a cooler 14 for cooling the medium inside the cooling pipe 13. The cooler 14 has an inlet pipe 1401 and a return pipe 1402, which is wound around the ash-reducing tank 5.

[0055] For example, such as Figure 1 As shown, cooling pipe 13 is wound around the causticization separation sedimentation tank 4, which can effectively regulate the temperature of the reaction system in the tank. In the oxalate metathesis precipitation process, the reaction temperature has an important impact on the precipitation effect and impurity removal efficiency. Through the circulation of the cooling medium in the cooling pipe, the heat generated in the reaction process can be removed in time, and the temperature in the causticization separation sedimentation tank 4 can be controlled within a suitable range. The return water pipe 1402 of the cooler 14 is wound around the lime slurry tank 5, so that the cooling medium coming out of the cooler cools the lime slurry tank before returning to the system circulation. The causticization liquid has a high temperature, and the reaction of quicklime dissolving into lime slurry after entering the lime slurry tank 5 releases a lot of heat. The setting of the return water pipe 1402 helps to maintain the temperature stability in the lime slurry tank 5, providing a good reaction environment for the preparation of lime slurry, thereby ensuring that the lime slurry can better participate in the impurity removal reaction after being introduced into the causticization separation sedimentation tank 4, and improving the operating efficiency of the entire impurity removal device.

[0056] In some examples, cooler 14 is a wide-channel plate heat exchanger.

[0057] For example, such as Figure 1As shown, the wide-channel plate heat exchanger has a large heat exchange area, and its unique plate structure design can increase the contact area and turbulence between the cooling medium and the object being cooled. In the oxalate metathesis precipitation and impurity removal device, this efficient heat exchange method can quickly transfer the heat generated in the causticization separation precipitation tank 4 and the ash-removing tank 5, so that the temperature in the tank can quickly reach and be maintained within a suitable reaction temperature range.

[0058] In some examples, a feeding device 15 is also included, which leads to the lime slaked tank 5 for adding quicklime to the lime slaked tank 5.

[0059] For example, such as Figure 1 As shown, the feeder 15 leads to the lime slurry tank 5, ensuring that quicklime can be added to the tank 5 in a timely and stable manner. In the oxalate metathesis precipitation and impurity removal process, quicklime is a key raw material for preparing lime slurry, which in turn plays a crucial role in the impurity removal reaction. The feeder 15 allows for the timely replenishment of quicklime according to production needs, preventing production interruptions due to raw material shortages. For example, in large-scale continuous production, as the reaction continues, the quicklime in the lime slurry tank 5 is continuously consumed. The feeder 15 can promptly add quicklime to ensure the stable preparation of lime slurry and maintain the normal operation of the impurity removal device.

[0060] The feeding unit 15 can be equipped with corresponding metering and control devices to achieve precise control of the amount of quicklime added. Different production conditions and impurity removal requirements may require different amounts of lime slurry to participate in the reaction. Precise control of the amount of quicklime added helps to accurately adjust the concentration and yield of lime slurry, thereby optimizing the effect of the impurity removal reaction. By precisely controlling the feeding amount, the impurity removal efficiency can be improved, reagent waste can be reduced, and production costs can be lowered.

[0061] In some examples, a drain pipe 16 is also included, which is connected to the seed tank 3 and is used for draining the seed tank 3.

[0062] The drain pipe 16 is connected to the seed tank 3, and different production conditions require different liquid levels in the seed tank 3. The presence of the drain pipe allows operators to flexibly adjust the liquid level in the seed tank 3 according to actual production needs, ensuring smooth production.

[0063] In some examples, both the overflow pump 11 and the mud pump 12 are unidirectional pumps.

[0064] For example, such as Figure 1As shown, the overflow pump 11 acts as a one-way pump, ensuring that the liquid can only flow from the causticization separation sedimentation tank 4 to the overflow tank 10, preventing backflow. Backflow would disrupt the sedimentation stratification already formed in the causticization separation sedimentation tank 4, causing precipitated impurities to re-mix into the liquid, affecting the sedimentation effect and subsequent impurity removal processes. The one-way pump ensures the smooth progress of the sedimentation process within the sedimentation tank, maintaining the stability of the liquid and guaranteeing the normal operation of the impurity removal device.

[0065] It should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and are not intended to limit it. Although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this disclosure without departing from the spirit and scope of the technical solutions of this disclosure, and all such modifications and substitutions should be covered within the scope of the claims of this disclosure.

Claims

1. An oxalate metathesis precipitation impurity removal device for removing impurities from an aluminum hydroxide filtrate produced by filtering a washed standing disk, characterized by, include: Seed cell (3); The causticization separation sedimentation tank (4) is connected to the seed tank (3) and the causticization separation sedimentation tank (4). Ashing tank (5), the causticization separation sedimentation tank (4) leads to the ashing tank (5); The lime slurry inlet pipe (6) leads to the lime slurry inlet pipe (6), and the lime slurry inlet pipe (6) leads to the causticization separation sedimentation tank (4).

2. The device for removing impurities by oxalate complex precipitation according to claim 1, characterized in that, Also includes: Drainage tube (1); The diversion pipe (2) has a first branch (201) and a second branch (202). The diversion pipe (1) is used to connect the washing plate with the diversion pipe (2). The first branch (201) is connected to the seed tank (3), and the second branch (202) leads to the causticization separation precipitation tank (4). The filter press (7) is connected to the causticization separation sedimentation tank (4), and the filter press (7) is connected to the seed tank (3).

3. The device for removing impurities by oxalate complex precipitation according to claim 2, characterized in that, The filter press (7) has a mixture inlet (701) and a liquid outlet (702), and the oxalate metathesis precipitation and impurity removal device further includes: Feed pump (8), the caustic separation sedimentation tank (4) is connected to the mixture inlet (701) through the feed pump (8), the feed pump (8) is used to send the sediment in the caustic separation sedimentation tank (4) into the mixture inlet (701). The underflow pump (9) is connected to the seed tank (3) via the liquid outlet (702).

4. The device for removing impurities by oxalate complex precipitation according to claim 1, characterized in that, Also includes: Overflow tank (10), the causticization separation sedimentation tank (4) is connected to the overflow tank (10); An overflow pump (11) is provided, and the overflow tank (10) is connected to the ash-making tank (5) through the overflow pump (11). The mud pump (12) is connected to the causticization separation sedimentation tank (4) through the mud pump (12).

5. The device for removing impurities by oxalate complex precipitation according to claim 4, characterized in that, The causticization separation sedimentation tank (4) has a top outlet (401) and a bottom outlet (402). The top outlet (401) leads to the overflow tank (10), and the height of the top outlet (401) is higher than the height of the overflow tank (10). The bottom outlet (402) leads to the mud pump (12).

6. The device for removing impurities by oxalate complex precipitation according to claim 1, characterized in that, Also includes: Cooling pipe (13), the cooling pipe (13) is wound around the causticization separation sedimentation tank (4); Cooler (14), the cooling pipe (13) leads to the cooler (14), the cooler (14) is used for cooling the medium in the cooling pipe (13), the cooler (14) has an inlet pipe (1401) and a return pipe (1402), the return pipe (1402) is wound around the ash-making tank (5).

7. The device for removal of impurities by oxalate metathesis precipitation according to claim 6, characterized in that, The cooler (14) is a wide-channel plate heat exchanger.

8. The device for removing impurities by oxalate complex precipitation according to claim 1, characterized in that, Also includes: Feeding component (15) leads to the lime-slaked tank (5) and is used to add quicklime to the lime-slaked tank (5).

9. The device for removing impurities by oxalate complex precipitation according to claim 1, characterized in that, Also includes: Drainage pipe (16) is connected to the seed tank (3) and is used for draining liquid from the seed tank (3).

10. The device for removal of impurities by oxalate complexation precipitation according to claim 4, characterized in that, The overflow pump (11) and the mud pump (12) are both one-way pumps. The overflow pump (11) and the mud pump (12) are both one-way pumps.

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