A system and method for impurity removal from a battery leachate

Abstract

This invention belongs to the field of battery material recycling technology and discloses a system and method for removing impurities from battery leachate. The system includes a removal reactor and a feeding assembly. The removal reactor comprises multiple reaction sections connected by U-shaped bends, allowing the reactor to extend upwards in a continuous S-shape. The pH values ​​within each reaction section are continuous and sequentially increase, enabling iron and aluminum impurities to precipitate in stages. Each reaction section is equipped with a filter assembly at its end. The feeding assembly is located at the beginning of the removal reactor to supply the leachate, allowing it to pass through the reaction sections sequentially. This system enables the large-scale precipitation of iron and aluminum in a lower pH environment, reducing the time required for precipitation and removal at higher pH levels. This effectively avoids high loss rates, reduces costs, and the S-shaped reactor significantly reduces floor space requirements, improving economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of battery material recycling technology, and in particular to a system and method for removing impurities from battery leachate. Background Technology

[0002] With the development of the new energy vehicle industry, ternary lithium-ion power batteries have become one of the mainstream choices in the market due to their high energy density and high output power. After these batteries are retired, they can be pre-treated to obtain ternary black powder containing various valuable metals such as nickel, cobalt, manganese, and lithium, which has great recycling value. Current technologies typically employ a three-step process of acid leaching, impurity removal, and separation to recover the metals from the ternary black powder. However, while leaching nickel, cobalt, manganese, and lithium, impurities such as iron and aluminum also enter the leaching solution, necessitating the removal of iron and aluminum ions from the battery leaching solution.

[0003] In existing technologies, multiple reactors are typically connected together, and the battery leachate flows between the reactors via overflow. This method can only control the pH within a certain range and cannot adjust the pH for different substances. This can lead to the precipitation of some nickel, cobalt, manganese, and lithium, resulting in a high loss rate of nickel, cobalt, manganese, and lithium (the nickel loss rate is usually greater than 5% in conventional processes). At the same time, different reactors must be arranged in a stepped manner, which increases the floor space and civil engineering costs, affecting economic efficiency.

[0004] In addition, in existing multi-reactor series processes, adjacent reactors are connected by overflow. Precipitated particles generated in the previous reactor will enter the subsequent reactor with the overflow liquid, interfering with the pH control accuracy of the subsequent stages. Furthermore, it is difficult to collect the precipitates in each stage separately, which reduces the controllability of the impurity removal process. Summary of the Invention

[0005] The purpose of this invention is to provide a purification system and method for battery leaching solutions, which enables iron and aluminum to precipitate in large quantities in a low pH environment, thereby reducing the precipitation and purification time of iron and aluminum in a high pH environment. This effectively avoids the problem of high loss rate caused by the large precipitation of metals that need to be recovered (such as nickel, cobalt, manganese, and lithium), reduces costs, and the S-shaped purification reactor significantly reduces the floor space required and improves economic efficiency.

[0006] To achieve this objective, the embodiments of the present invention adopt the following technical solutions: A battery leaching solution impurity removal system for removing iron and aluminum impurities from the battery leaching solution, comprising: The impurity removal reactor includes multiple reaction sections, adjacent reaction sections are connected by U-shaped bends, so that the impurity removal reactor extends upward in a continuous S-shape, and the pH value range within the multiple reaction sections is continuous and increases sequentially, so that the iron impurities and the aluminum impurities precipitate in stages, and each reaction section is provided with a filter assembly at the end. A feeding assembly is provided at the beginning of the impurity removal reactor to feed the impurity removal reactor, so that the battery leachate passes through multiple reaction sections in sequence.

[0007] Preferably, the impurity removal reactor comprises four reaction sections, and the pH values ​​of the four reaction sections along the flow direction of the battery leachate are pH1, pH2, pH3, and pH4, respectively, with 2.8 ≤ pH1 < 3, 3 ≤ pH2 < 3.5, 3.5 ≤ pH3 < 4, and 4 ≤ pH4 < 4.5.

[0008] Preferably, of the four reaction sections, the first two reaction sections are controlled at a temperature of 50°C to 70°C, and the latter two reaction sections are controlled at a temperature of 80°C to 100°C.

[0009] Preferably, each of the reaction sections is provided with a pH control component, which includes an alkali supply head and a pH sensor. The alkali supply head is used to supply alkali to the reaction section to control the pH value within the reaction section. The pH sensor is used to detect the pH value within the reaction section, and the alkali supply head is located upstream of the pH sensor along the flow direction of the battery leaching solution.

[0010] Preferably, vibration is applied to the battery leachate in the impurity removal reactor, the feeding assembly performs pulsating feeding, and the feeding pulsation frequency of the battery leachate is the same as the vibration frequency of the battery leachate.

[0011] Preferably, the impurity removal system further includes a vibration generator connected to the starting end of the impurity removal reactor. The vibration generator is used to apply vibration to the battery leachate in the impurity removal reactor, and the vibration direction is the same as the flow direction of the battery leachate; and / or, The feeding assembly includes a diaphragm plunger pump, which drives the flow of the battery leaching solution.

[0012] Preferably, the filtration assembly includes two automatic backwash filters, both of which are connected to the end of the corresponding reaction section, and the two automatic backwash filters work alternately, automatically switching backwashing triggered by pressure difference or timed switching.

[0013] Preferably, each reaction section is provided with multiple baffles, and the baffles are provided with flow holes.

[0014] Preferably, the area of ​​the flow passage is 60% to 80% of the flow cross-sectional area of ​​the impurity removal reactor.

[0015] A method for removing impurities from battery leaching solution, capable of removing iron and aluminum impurities from the battery leaching solution, the method comprising: The battery leachate is passed into a purification reactor having multiple sequentially connected reaction sections, and the battery leachate is passed through the multiple reaction sections in sequence, with the pH value of the multiple reaction sections increasing sequentially to cause the iron impurities and the aluminum impurities to precipitate in stages. After the precipitates generated in each reaction section are removed by filtration at the end of the reaction section, the battery leachate then enters the next reaction section. Each reaction section uses PID control to regulate the amount of alkali added, thus maintaining the pH value of that section.

[0016] The beneficial effects of this invention are: This invention provides a system and method for removing impurities from battery leachate. In this system, multiple reaction sections of the impurity removal reactor are sequentially connected by curved connecting sections, causing the reactor to extend upwards in an S-shape. When the feeding assembly supplies the battery leachate, it generally flows upwards. This means that the battery leachate spontaneously accumulates under gravity, filling the reactor and maintaining stability, allowing for precise control of the flow rate. Furthermore, it overcomes the shortcomings of existing multi-reactor series systems, which require a stepped arrangement, have a large footprint, and incur high civil engineering costs. While ensuring the total reaction length meets the requirements of segmented reactions, the system's footprint is significantly reduced. The pH range within the multiple reaction sections is continuous and sequentially increases, allowing iron and aluminum impurities in the battery leachate to precipitate in large quantities at lower pH levels, thus reducing the time required for precipitation and removal of iron and aluminum impurities at higher pH levels.

[0017] This impurity removal system enables iron and aluminum to precipitate in large quantities in a low pH environment, thereby reducing the precipitation and impurity removal time of iron and aluminum in a high pH environment. It effectively avoids the problem of high loss rate caused by the large precipitation of metals that need to be recovered (such as nickel, cobalt, manganese, and lithium), reduces costs, and the S-shaped impurity removal reactor significantly reduces the footprint and improves economic efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the battery leaching solution removal system provided in an embodiment of the present invention.

[0019] In the picture: 1. Impurity removal reactor; 11. First section; 12. Second section; 13. Third section; 14. Fourth section; 15. Connecting section; 16. First connecting pipe; 2. Raw material tank; 3. Driving components; 4. Storage tank; 51. Vibration generator; 52. Hoses; 53. Isolating element; 54. Second connecting pipe; 6. Baffle; 61. Flow hole; 7. Filter components; 8. Temperature sensor; 9. pH control component; 91. Alkali supply head; 92. pH sensor. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] In this invention, the terms "comprising," "including," "having," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0022] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, in this invention, the character " / " generally indicates that the preceding and following related objects have an "and / or" relationship.

[0023] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," "fixed," "combined," "coupled," and "installed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection via an intermediate medium; or the internal communication of two components or the interaction between two components. As examples, a direct connection refers to two parts or components being connected together without the need for an intermediate medium, while an indirect connection refers to two parts or components each being connected to at least one intermediate medium, with the connection achieved through the intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, "connected" and "coupled" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0024] In this invention, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the value and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​not using relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0025] In this invention, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0026] In the description of this invention, the terms "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationships shown in the accompanying drawings. They are used solely for ease of description and simplification of operation, and do not 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 invention. Furthermore, in the context, it should be understood that when an element is mentioned as being "upper" or "lower" of another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "above," "on top of," "upper side of," and "above" of the first feature and the second feature include the first feature being directly above, to the upper left, to the upper right, to the upper front, and to the upper rear of the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature. The terms "below," "under," "below," and "below" for "first feature" and "second feature" include situations where the first feature is directly below, to the lower left, to the lower right, in front of, or behind the second feature, or simply indicate that the first feature is at a lower horizontal level than the second feature. Furthermore, the terms "first" and "second" are used merely for descriptive distinction and have no specific meaning.

[0027] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] Existing technologies typically employ a three-step process of acid leaching, impurity removal, and separation to recover metals from ternary lithium batteries. This involves leaching the ternary lithium batteries with sulfuric acid and a reducing agent, causing nickel, cobalt, manganese, and lithium to enter the solution as ions, forming a battery leachate. The components are then separated through chemical precipitation or extraction. However, this process also introduces iron and aluminum impurities into the leachate, necessitating the removal of these ions.

[0029] In existing technologies, multiple reactors are typically connected together, and the battery leachate flows between the reactors via overflow. This method can only control the pH within a certain range and cannot adjust the pH for different substances. This can lead to the precipitation of some nickel, cobalt, manganese, and lithium, resulting in a high loss rate of nickel, cobalt, manganese, and lithium. At the same time, different reactors must be arranged in a stepped manner, which increases the floor space and civil engineering costs, affecting economic efficiency.

[0030] To address the aforementioned issues, this embodiment provides a battery leaching solution impurity removal system (hereinafter referred to as the impurity removal system). The impurity removal system includes an impurity removal reactor 1 and a feeding assembly. The impurity removal reactor 1 includes multiple reaction sections, with adjacent reaction sections connected by U-shaped bends 15, so that the impurity removal reactor 1 extends continuously upward in an S-shape. The pH value range within the multiple reaction sections is continuous and increases sequentially, allowing iron and aluminum impurities to precipitate in stages. Each reaction section is equipped with a filter assembly 7 at its end to remove precipitates generated in that reaction section. The feeding assembly is located at the beginning of the impurity removal reactor 1 to supply the impurity removal reactor 1, allowing the battery leaching solution to pass through the multiple reaction sections sequentially.

[0031] In this impurity removal system, multiple reaction sections of the impurity removal reactor 1 are connected sequentially by curved connecting sections 15, causing the impurity removal reactor 1 to extend upward in an S-shape. When the feeding component supplies the feed, the battery leachate generally flows upward. That is to say, the battery leachate will spontaneously accumulate under the action of gravity, filling the impurity removal reactor 1 and maintaining stability, which can accurately control the flow rate of the battery leachate. Moreover, it solves the defects of existing multi-reactor series connections that require a stepped arrangement, large footprint, and high civil engineering costs. Under the premise of ensuring that the total reaction length meets the requirements of segmented reaction, the footprint of the impurity removal system is significantly reduced. The pH range within the multiple reaction sections is continuous and increases sequentially, allowing iron and aluminum impurities in the battery leachate to precipitate in large quantities in a lower pH environment. This means that the battery leachate does not need to react for too long in a higher pH environment, effectively avoiding the problem of high loss rate caused by the large precipitation of metals to be recovered (such as nickel, cobalt, manganese, and lithium).

[0032] This impurity removal system enables iron and aluminum to precipitate in large quantities in a low pH environment, thereby reducing the precipitation and impurity removal time of iron and aluminum in a high pH environment. It effectively avoids the problem of high loss rate caused by the large precipitation of metals that need to be recovered (such as nickel, cobalt, manganese and lithium), reduces costs, and the S-type impurity removal reactor 1 significantly reduces the footprint and improves economic efficiency.

[0033] Specifically, in this embodiment, the impurity removal reactor 1 includes four reaction sections along the flow direction of the battery leachate. The pH values ​​of the four reaction sections are pH1, pH2, pH3, and pH4, respectively, and 2.8 ≤ pH1 < 3, 3 ≤ pH2 < 3.5, 3.5 ≤ pH3 < 4, and 4 ≤ pH4 < 4.5.

[0034] In other words, first adjust the pH of the battery leachate to 2.8-3 to allow iron to begin to precipitate, and a small amount of aluminum to be adsorbed and precipitated by ferric hydroxide; then adjust the pH of the battery leachate to 3-3.5 to allow a large amount of iron to precipitate, and aluminum to begin to precipitate; then adjust the pH of the battery leachate to 3.5-4 to allow iron to precipitate completely, and aluminum to precipitate in large quantities; finally, adjust the pH of the battery leachate to 4-4.5 to allow aluminum to precipitate completely.

[0035] For ease of explanation, the four reaction sections along the flow direction of the battery leaching solution are referred to as Section 11, Section 2, Section 3, and Section 4. When the battery leachate flows to the first stage (11), iron ions in the battery leachate begin to form ferric hydroxide precipitate. Simultaneously, since 2.8-3 is close to the pH at which aluminum ions begin to precipitate, aluminum ions also form a small amount of aluminum hydroxide precipitate. Furthermore, due to the low pH at this point, the precipitation rate of ferric hydroxide precipitate is low, resulting in a flocculent morphology of ferric hydroxide, which can also adsorb the formed aluminum hydroxide precipitate, thus promoting the precipitation of aluminum ions. When the battery leachate flows to the second stage (12), the pH is adjusted to 3-3.5, and iron ions in the battery leachate form a large amount of ferric hydroxide precipitate, while aluminum ions also begin to precipitate aluminum hydroxide precipitate more rapidly. When the battery leachate flows to the third stage (13), the pH is adjusted to 3.5-4, and aluminum ions begin to form a large amount of aluminum hydroxide precipitate; iron ions are almost non-existent in the battery leachate. When the battery leachate flows to the fourth stage (14), the pH is adjusted to 4-4.5, and almost all aluminum ions form aluminum hydroxide precipitate.

[0036] In other words, iron and aluminum can precipitate in large quantities in a lower pH environment, thereby reducing the time required for iron and aluminum to precipitate and remove impurities in a higher pH environment. This effectively avoids the large-scale precipitation of metals that need to be recovered (such as nickel, cobalt, manganese, and lithium), effectively avoids the problem of high loss rates of metals that need to be recovered, reduces costs, and improves economic efficiency.

[0037] Preferably, along the flow direction of the battery leaching solution, the pH value of the battery leaching solution in the first section 11, the second section 12, the third section 13, and the fourth section 14 all gradually increase.

[0038] In other words, regardless of where the battery leachate is in the impurity removal reactor 1, the pH value at the same location gradually increases as the battery leachate flows, thereby causing iron and aluminum ions to gradually precipitate out. The rate of hydroxide precipitation is relatively slow, avoiding the concentrated precipitation of iron hydroxide and aluminum hydroxide due to abrupt pH fluctuations, which would affect the overall precipitation rate and ensure a stable environment during the impurity removal process.

[0039] It is worth noting that the pH values ​​of the battery leaching solution in the first segment 11, the second segment 12, the third segment 13, and the fourth segment 14 all change continuously.

[0040] Preferably, along the flow direction of the battery leachate, the pH values ​​of the first segment 11 can be 2.8, 2.9 and 3 in sequence; the pH values ​​of the second segment 12 can be 3, 3.1, 3.2, 3.3, 3.4 and 3.5 in sequence; the pH values ​​of the third segment 13 can be 3.5, 3.6, 3.7, 3.8, 3.9 and 4 in sequence; and the pH values ​​of the fourth segment 14 can be 4, 4.1, 4.2, 4.3, 4.4 and 4.5 in sequence.

[0041] It is worth noting that although the fourth pH range is 4~4.5, which is lower than the second complete precipitation pH of aluminum ions, the use of this impurity removal method allows the battery leachate to precipitate for a long time in a lower pH range. Furthermore, the ferric hydroxide precipitate can further adsorb aluminum ions and precipitate, thus ensuring the complete precipitation of aluminum ions. Moreover, by reducing the maximum pH value during the impurity removal process, the amount of nickel, cobalt, manganese, and lithium precipitated can be effectively reduced, thereby improving the recovery rate of nickel, cobalt, manganese, and lithium.

[0042] In order to precisely control the pH value of the battery leachate in each reaction section, in this embodiment, each reaction section is equipped with a pH control component 9. The pH control component 9 includes an alkali supply head 91 and a pH sensor 92. The alkali supply head 91 is used to supply alkali to the reaction section to control the pH value in the reaction section. The pH sensor 92 is used to detect the pH value in the reaction section. Along the flow direction of the battery leachate, the alkali supply head 91 is located upstream of the pH sensor 92, that is, the battery leachate first flows through the alkali supply head 91 of the pH control component 9, and then flows through the pH sensor 92 of the pH control component 9.

[0043] The opening and closing of the alkali replenishment head 91 and the replenishment amount are controlled by PID (Proportional-Integral-Derivative control). The PID controller dynamically adjusts the alkali flow rate of the upstream alkali replenishment head 91 based on the real-time detection value of the downstream pH sensor, thereby achieving pH advance control. If the pH sensor 92 detects that the pH value in the reaction interval is not within the corresponding preset range within 2 minutes, the system can adjust the corresponding alkali replenishment head 91 to replenish alkali according to the pH value. The alkali is continuously added, and the addition flow rate is dynamically adjusted by the PID.

[0044] To further improve the accuracy of pH control, multiple pH control components 9 are installed in the first section 11, the second section 12, the third section 13 and the fourth section 14 to monitor the pH of the battery leaching solution and replenish the alkali solution at multiple points.

[0045] In this embodiment, three sets of pH control components 9 are provided in the first section 11 of the impurity removal reactor 1. The pH sensors 92 of the three sets of pH control components 9 are located at 10%, 50%, and 80% of the distance from the starting end of the first section 11, respectively. Correspondingly, the alkali replenishment heads 91 of the three sets of pH control components 9 are located at the starting end of the first section 11, 40%, and 70% of the distance from the starting end, respectively. This ensures that the pH value of the battery leachate can be controlled as soon as it enters the first section 11, and that the pH of the battery leachate can be stabilized until the battery leachate flows out of the first section 11.

[0046] Similarly, three sets of pH control components 9 are provided in the second section 12 of the impurity removal reactor 1. The pH sensors 92 of the three sets of pH control components 9 are located at 10%, 50% and 80% of the distance from the starting end of the second section 12, respectively. Correspondingly, the alkali replenishment heads 91 of the three sets of pH control components 9 are located at the starting end of the second section 12, at 40% and 70% of the distance from the starting end, respectively. Similarly, three sets of pH control components 9 are provided in the third section 13 of the impurity removal reactor 1. The pH sensors 92 of the three sets of pH control components 9 are located at 10%, 50% and 80% of the distance from the starting end of the third section 13, respectively. Correspondingly, the alkali replenishment heads 91 of the three sets of pH control components 9 are located at the starting end of the third section 13, at 40% and 70% of the distance from the starting end, respectively. Similarly, three sets of pH control components 9 are provided in the fourth section 14 of the impurity removal reactor 1. The pH sensors 92 of the three sets of pH control components 9 are located at 10%, 50% and 80% of the distance from the starting end of the fourth section 14, respectively. Correspondingly, the alkali replenishment heads 91 of the three sets of pH control components 9 are located at the starting end of the fourth section 14, at 40% and 70% of the distance from the starting end, respectively.

[0047] In other embodiments, more sets of pH control components 9 are provided in the first section 11, the second section 12, the third section 13 and the fourth section 14 to further refine the pH control of the battery leachate, ensuring that the pH value of the battery leachate in the first section 11, the second section 12, the third section 13 and the fourth section 14 of the impurity removal reactor 1 meets the preset value, thereby ensuring the stability of the precipitation environment of iron ions and aluminum ions during the impurity removal process and ensuring the consistency of the impurity removal results.

[0048] In this embodiment, the feeding assembly includes a raw material tank 2 and a drive unit 3. The raw material tank 2 stores battery leachate and is connected to the first section 11 via the drive unit 3. A storage tank 4 is connected to the end of the impurity removal reactor 1 for temporarily storing the battery leachate after impurity removal and for providing raw materials for subsequent nickel-cobalt-manganese-lithium recovery.

[0049] In this embodiment, vibration is applied to the battery leachate in the impurity removal reactor 1, and the feeding assembly performs pulsating feeding. The feeding pulsation frequency of the battery leachate is the same as the vibration frequency of the battery leachate, so as to superimpose small-amplitude reciprocating oscillations without changing the net flow rate of the battery leachate. The two are at the same frequency to achieve uniform mixing in a coordinated manner and avoid the breakage of precipitated particles.

[0050] In this embodiment, the driving component 3 is a diaphragm plunger pump, which drives the flow of battery leaching solution. The diaphragm plunger pump achieves flow regulation by adjusting the pump's stroke frequency (motor speed). Typically, a frequency converter is used to control the motor speed to continuously and linearly regulate the feed flow rate. By using a diaphragm plunger pump to drive the flow of battery leaching solution, the flow rate of the battery leaching solution can be precisely controlled.

[0051] To apply vibration to the battery leachate, the impurity removal system also includes a vibration generator 51, which is connected to the starting end of the impurity removal reactor 1, i.e., the starting end of the first section 11. The vibration generator 51 is used to apply vibration to the battery leachate in the impurity removal reactor 1, and the vibration direction is the same as the flow direction of the battery leachate. By precisely controlling the vibration frequency and amplitude of the battery leachate, the battery leachate can be made to vibrate back and forth in the impurity removal reactor 1. Since the vibration direction is the same as the flow direction of the battery leachate, this vibration can ensure that the ferric hydroxide precipitate and aluminum hydroxide precipitate are evenly distributed in the impurity removal reactor 1 without affecting the flow rate of the battery leachate, while avoiding the breakage of precipitate particles and facilitating filtration and separation.

[0052] Specifically, the vibration frequency of the battery leachate is 1-10 Hz. This vibration frequency should not be too high, as excessively high vibration frequencies can easily lead to the breakage of sediment particles. It is worth noting that the vibration frequency of the battery leachate can be 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz, 6 Hz, 7 Hz, 8 Hz, 9 Hz, or 10 Hz, with 5 Hz being preferred.

[0053] In addition, to prevent leakage of battery leaching solution, the impurity removal system also includes a hose 52, an isolator 53, and a second connecting pipe 54. The raw material tank 2 is connected to the starting end of the first section 11 through the first connecting pipe 16. The diaphragm plunger pump is installed on the first connecting pipe 16. The second connecting pipe 54 is also connected to the starting end of the first section 11 and is arranged in the same direction as the first section 11. The vibration generator 51 is connected to the hose 52, and the isolator 53 is installed between the hose 52 and the second connecting pipe 54.

[0054] This structure facilitates the direct transmission of vibration from the vibration generator 51 to the first section 11, causing vibration of the battery leaching fluid. On the other hand, the flexible hose 52 enables a soft connection between the vibration generator 51 and the second connecting pipe 54, preventing resonance between the vibration generator 51, the second connecting pipe 54, and the first section 11. The isolation component 53 prevents battery leaching fluid from leaking into the vibration generator 51 and causing it to fail, while also preventing the loss of battery leaching fluid.

[0055] It is worth noting that the ends of the first segment 11, the second segment 12, the third segment 13 and the fourth segment 14 are all equipped with filter components 7, which filter out the sediment generated in the corresponding stage and ensure the cleanliness of the battery leaching solution entering the next stage.

[0056] In this embodiment, the filter assembly 7 includes two automatic backwash filters, both of which are connected to the end of the corresponding reaction section, and the two automatic backwash filters work alternately, automatically switching backwash by pressure difference or timed trigger.

[0057] When the filter cake thickens, causing the differential pressure to rise, the system automatically switches to the standby unit and automatically backwashes the clogged unit, achieving uninterrupted continuous filtration. It's worth noting that backwash filters are existing technology; simply selecting a suitable and mature product based on the parameters is sufficient, and will not be elaborated upon here.

[0058] In this embodiment, multiple baffles 6 are spaced apart in each reaction section, and each baffle 6 has a flow hole 61. These baffles 6 can obstruct the flow of the battery leachate, allowing it to move slowly forward at a low flow rate. At the same time, the vibration generator 51 can also drive the fluid to make small-amplitude reciprocating motions between adjacent baffles 6. When the battery leachate flows through each baffle 6, the vibration of the battery leachate will generate eddies with periodically changing directions in front of and behind the baffle 6, improving the uniformity of precipitation distribution, avoiding precipitation accumulation that would affect the local flow rate of the battery leachate, and ensuring that the battery leachate maintains a stable flow throughout the entire impurity removal reactor 1.

[0059] Preferably, the distance between two adjacent baffles 6 is 0.5 to 1 times the pipe diameter. The distance between two adjacent baffles 6 should not be too large or too small. If it is too large, the flow obstruction effect will be insignificant and the battery leaching liquid will not be able to make small-amplitude reciprocating movements between the adjacent baffles 6, which is not conducive to the uniform distribution of precipitation. If it is too small, it will affect the flow of the battery leaching liquid, resulting in excessive resistance and increased energy consumption.

[0060] Specifically, the distance between two adjacent baffles 6 can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1 times the pipe diameter.

[0061] Preferably, the area of ​​the flow passage 61 on the baffle 6 is 60% to 80% of the flow cross-sectional area of ​​the impurity removal reactor 1. The area of ​​the flow passage 61 should not be too large or too small. If it is too large, the flow obstruction effect will be insignificant. If it is too small, it will seriously affect the normal flow of the battery leaching solution and easily cause an excessive difference in the flow rate of the battery leaching solution before and after the baffle 6, thus affecting the overall impurity removal effect.

[0062] Specifically, the area of ​​the flow passage 61 on the baffle 6 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, or 80% of the flow cross-sectional area of ​​the impurity removal reactor 1.

[0063] In some embodiments, a baffle 6 may also be provided within the curved connecting section 15 to further enhance the flow resistance to battery leaching fluid.

[0064] In this embodiment, the temperature of the battery leachate is maintained between 20°C and 100°C. This temperature should not be too high or too low. If the temperature is too high, the state of the battery leachate will be unstable and the solubility of each component will be affected. If the temperature is too low, the reaction rate will be slow, affecting the impurity removal efficiency. Specifically, the temperature of the battery leachate can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C.

[0065] To balance reaction rate and energy consumption, in this embodiment, the first two reaction stages are controlled at 50℃~70℃, and the latter two reaction stages are controlled at 80℃~100℃. Preferably, the first two reaction stages can be controlled at 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, or 70℃, and the latter two reaction stages can be controlled at 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, or 100℃.

[0066] In this embodiment, temperature sensors 8 are provided at the starting ends of the first segment 11, the second segment 12, the third segment 13, and the fourth segment 14. The exterior of the impurity removal reactor 1 is covered with a heating layer, which can be heated in segments. When the temperature sensor 8 detects that the temperature of the battery leachate entering the first segment 11, the second segment 12, the third segment 13, and the fourth segment 14 is lower than a preset temperature, the corresponding position can be heated by the heating layer to ensure the stability of the battery leachate temperature.

[0067] In this embodiment, the alkaline solution used to adjust the pH of the battery leachate is a sodium carbonate solution with a concentration of 15% to 20%, to ensure that the pH of the battery leachate changes gradually. Specifically, the concentration of the sodium carbonate solution can be 15%, 16%, 17%, 18%, 19%, or 20%.

[0068] In this embodiment, the battery leachate is applied for 0.5 h to 1 h in each of the first stage 11, the second stage 12, the third stage 13, and the fourth stage 14. This ensures effective precipitation while avoiding excessive time that could affect the impurity removal efficiency. Specifically, the application time of the battery leachate in the first stage 11, the second stage 12, the third stage 13, and the fourth stage 14 can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, or 1 h.

[0069] Table 1 Table 1 shows the composition of the battery leachate in this embodiment. In this embodiment, the battery leachate in Table 1 is treated with a purification system to remove impurities. The treatment conditions are as follows: the feed frequency is 5Hz, the time for the battery leachate in the first stage 11, the second stage 12, the third stage 13, and the fourth stage 14 is 0.5h, the temperature of the battery leachate in the first stage 11 and the second stage 12 is maintained at 60℃, and the temperature of the battery leachate in the third stage 13 and the fourth stage 14 is maintained at 90℃. The purification results are shown in Table 2.

[0070] Table 2 It is worth noting that in conventional processes, the loss rate of nickel is usually greater than 5%, the loss rate of cobalt is greater than 3%, and the loss rate of manganese and lithium is greater than 2%. According to the data in Table 2, the impurity removal method of the present invention significantly reduces the loss rate of nickel, cobalt, manganese, and lithium.

[0071] To demonstrate the effectiveness of this impurity removal method using experimental data, several sets of comparative experiments with different conditions were designed for data comparison.

[0072] Comparative Example 1 This comparative example changed the number of reaction stages in the impurity removal process from four stages in this embodiment to three stages, thereby verifying the effect of the number of reaction stages on the loss rate of nickel, cobalt, manganese, and lithium. The pH ranges corresponding to the three stages were 2.8–3.2 (primarily for iron ion removal), 3.2–4.0 (primarily for aluminum ion removal), and 4.0–4.5 (for deep aluminum ion removal), respectively. The experimental results are shown in Table 3.

[0073] Table 3 Reducing the number of reaction stages increased the loss rate of nickel-cobalt-manganese-lithium (NiCoMn) lithium. Analysis revealed that this was because with fewer reaction stages, the solution still contained a large amount of aluminum ions in the high pH stage. The precipitation of these aluminum ions carried away NiCoMn, leading to a higher loss rate.

[0074] Comparative Example 2 The comparative example changed the vibration frequency during the impurity removal process from 5Hz in this example to 10Hz, while keeping the amplitude unchanged, thereby verifying the effect of high-frequency oscillation on the dispersibility of precipitated particles. The experimental results are shown in Table 4.

[0075] Table 4 As can be seen from the data in Table 4, the loss rate of each metal ion increases slightly after increasing the vibration frequency of the battery leachate. In other words, the vibration frequency needs to be within a suitable range. Increasing the vibration frequency will not only weaken the impurity removal effect, but also cause the precipitate particles to become finer, affecting the filtration efficiency and increasing energy consumption.

[0076] Comparative Example 3 The comparative example changed the feeding frequency during the impurity removal process from 5Hz in this embodiment to 10Hz, which means changing the feeding frequency of the diaphragm plunger pump to 10Hz. This increases the flow rate of the battery leachate and shortens the reaction time of the battery leachate in each stage. The experimental results are shown in Table 5.

[0077] Table 5 The data in Table 5 shows that increasing the feed frequency and reducing the reaction time in each stage resulted in a 100% removal rate for iron ions, while the removal rate for aluminum ions decreased slightly. This indicates that reducing the reaction time in each stage to improve efficiency leads to a decrease in the removal rate of aluminum ions. Furthermore, Table 5 also shows a slight increase in the loss rate of nickel, cobalt, manganese, and lithium. This is because the shorter reaction time in the first stage reduces the removal rate of iron ions, resulting in excessively high iron ion concentrations in the subsequent three stages. Under high pH conditions, the precipitation of ferric hydroxide adsorbs some nickel, cobalt, manganese, and lithium, leading to an increased loss rate.

[0078] Comparative Example 4 The comparative example changed the temperature of the battery leaching solution in the first stage during the impurity removal process, from 60°C in this example to 90°C. The experimental results are shown in Table 6.

[0079] Table 6 As can be seen from the data in Table 6, increasing the temperature of the battery leachate in the first stage resulted in similar removal rates of iron and aluminum ions and loss rates of nickel, cobalt, manganese, and lithium as in this embodiment. This indicates that increasing the temperature of the first stage has little impact on the results. Considering the economic efficiency of the process, the temperature of the first stage can be selected as 60°C.

[0080] In addition, in order to compare the impurity removal effect with the impurity removal method in the prior art, this embodiment also provides a comparative example of performing impurity removal operation according to the impurity removal method in the prior art.

[0081] Comparative Example 5 The comparative proportion is purified according to the existing process method, and the working method is as follows: After heating the battery leaching solution to 90°C, a 20% sodium carbonate solution was slowly and uniformly added to the leaching solution. The pH of the battery leaching solution was adjusted to 4.5, and the reaction was carried out at 90°C for 2 hours. After the reaction was completed, the solution was filtered. The experimental results are shown in Table 7.

[0082] Table 7 Compared with the final data in Table 2, the loss rates of nickel, cobalt, manganese, and lithium are all higher in Table 7.

[0083] Comparative Example 6 The comparative example had only one reaction stage, with the pH adjusted to 4.5, a total residence time of 2 hours, and the temperature controlled at 90℃. After the reaction was completed, the mixture was filtered. The experimental results are shown in Table 8.

[0084] Table 8 In summary, the impurity removal method in this embodiment is the optimal solution, which can retain nickel, cobalt, manganese and lithium to the maximum extent while ensuring the removal of iron ions and aluminum ions, effectively avoiding the problem of high loss rate of metals that need to be recycled, reducing costs and improving economic benefits.

[0085] This embodiment also provides a method for removing impurities from battery leaching solution (hereinafter referred to as the impurity removal method), which can remove iron and aluminum impurities from battery leaching solution. The impurity removal method includes: The battery leachate is fed into a purification reactor 1, which has multiple sequentially connected reaction sections. The battery leachate is passed through multiple reaction sections in sequence, and the pH value of each reaction section is increased sequentially to allow iron and aluminum impurities to precipitate in stages. After the precipitates produced in each reaction section are removed by filtration at the end of the reaction section, the battery leachate enters the next reaction section. Each reaction section uses PID control to regulate the amount of alkali added, thus maintaining the pH value of that section.

[0086] The pH range within multiple reaction stages is continuous and increases sequentially, allowing iron and aluminum impurities in the battery leachate to be removed stepwise in a suitable pH environment. This prevents the battery leachate from reacting for too long in a high pH environment, effectively avoiding the problem of high loss rates due to the precipitation of large amounts of metals to be recovered (such as nickel, cobalt, manganese, and lithium). At the end of each reaction stage, precipitates generated in that stage are removed by filtration, ensuring the cleanliness of the battery leachate entering the next stage and preventing the adsorption of valuable metals by precipitation. The PID controller dynamically adjusts the alkaline flow rate of the upstream alkaline replenishment head 91 based on the real-time detection value of the downstream pH sensor, achieving proactive pH control. If the pH sensor 92 detects that the pH value in the reaction interval is not within the corresponding preset range within 2 minutes, the system can adjust the corresponding alkaline replenishment head 91 to replenish alkaline according to the pH value. The alkaline solution is continuously added, and the addition flow rate is dynamically adjusted by the PID controller.

[0087] Preferably, the impurity removal reactor 1 includes four reaction sections. The first section 11 and the second section 12 of the impurity removal reactor 1 have lower pH values, while the third section 13 and the fourth section 14 have higher pH values. This allows iron and aluminum to precipitate in large quantities in a lower pH environment, thereby reducing the time required for iron and aluminum to precipitate and remove impurities in a higher pH environment. This effectively avoids the large-scale precipitation of metals that need to be recovered (such as nickel, cobalt, manganese, and lithium), effectively avoids the problem of high loss rates of metals that need to be recovered, reduces costs, and improves economic efficiency.

[0088] In this embodiment, the impurity removal method further includes driving the battery leachate to flow sequentially through the first section 11, the second section 12, the third section 13, and the fourth section 14, and applying vibration to the battery leachate, with the vibration direction being the same as the flow direction of the battery leachate. By precisely controlling the vibration frequency and amplitude of the battery leachate, the battery leachate can be made to vibrate back and forth in the impurity removal reactor 1. Since the vibration direction is the same as the flow direction of the battery leachate, this vibration can ensure that the iron hydroxide precipitate and aluminum hydroxide precipitate are uniformly distributed in the impurity removal reactor 1 without affecting the flow velocity of the battery leachate, while avoiding the breakage of precipitate particles and facilitating filtration and separation.

[0089] Specifically, the vibration frequency of the battery leachate is 1~10Hz. This vibration frequency should not be too high, as an excessively high vibration frequency can easily lead to the breakage of sediment particles. It is worth noting that the vibration frequency of the battery leachate can be 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz, 6 Hz, 7 Hz, 8 Hz, 9 Hz or 10 Hz, with 5 Hz being preferred.

[0090] Preferably, a diaphragm plunger pump is used to drive the flow of the battery leachate, and the feed pulsation frequency of the battery leachate is the same as its vibration frequency. The diaphragm plunger pump achieves flow regulation by adjusting the pump's stroke frequency (motor speed). Typically, a frequency converter is used to control the motor speed to continuously and linearly regulate the feed flow rate. Using a diaphragm plunger pump to drive the flow of the battery leachate allows for precise control of the flow rate. Simultaneously, it ensures that the feed pulsation frequency of the battery leachate is the same as its vibration frequency, allowing for the superposition of small-amplitude reciprocating oscillations without changing the net flow rate of the battery leachate. These two elements work together to achieve uniform mixing and prevent the breakage of precipitated particles.

[0091] Specifically, the vibration of the battery leachate is achieved by the vibration generator 51. There are no mechanical stirring paddles or moving mechanical parts in the impurity removal reactor 1, which can effectively avoid the collision and breakage between the precipitated particles and the stirring paddle.

[0092] In this embodiment, the impurity removal method further includes real-time monitoring of the pH value of the battery leachate in the first section 11, the second section 12, the third section 13, and the fourth section 14. Multiple alkali replenishment heads 91 are installed in each of the first, second, third, and fourth sections 14. Alkali is replenished through these replenishment heads 91 based on the pH monitoring results. By utilizing multiple alkali replenishment heads 91, the pH value of the battery leachate in the first, second, second, third, third, and fourth sections 14 of the impurity removal reactor 1 can be ensured to meet the preset value, thereby ensuring a stable precipitation environment for iron and aluminum ions during the impurity removal process and guaranteeing the consistency of the impurity removal results.

[0093] In this embodiment, the impurity removal method further includes filtering the battery leachate at the ends of the first section 11, the second section 12, the third section 13 and the fourth section 14, so as to ensure that the precipitate particles generated by the battery leachate in each section of the impurity removal reactor 1 can be filtered, and to prevent the precipitate particles from entering the next section and affecting the precipitation of the battery leachate in the next section.

[0094] Preferably, two backwash filters are used to filter the battery leachate in the first section 11, the second section 12, the third section 13, and the fourth section 14. One backwash filter is in standby mode, and the switching is automatically triggered by a differential pressure sensor or timer. When the filter cake thickens, causing the differential pressure to rise, the system automatically switches to the standby unit and automatically backwashes the clogged unit, achieving uninterrupted continuous filtration. It is worth noting that the backwash filter is existing technology; only a suitable and mature product needs to be selected based on the parameters, and will not be elaborated further here.

[0095] In this embodiment, the impurity removal method further includes using a baffle 6 with a flow hole 61 to obstruct the flow of the battery leachate. The baffle 6 can obstruct the flow of the battery leachate, allowing it to move slowly forward at a low flow rate. At the same time, the vibration generator 51 can also drive the fluid to make small-amplitude reciprocating motions between adjacent baffles 6. As the battery leachate flows through each baffle 6, the vibration of the battery leachate will generate eddies with periodically changing directions before and after the baffle 6, improving the uniformity of precipitation distribution, preventing precipitation accumulation from affecting the local flow rate of the battery leachate, and ensuring that the battery leachate maintains a stable flow throughout the entire impurity removal reactor 1.

[0096] Preferably, the distance between two adjacent baffles 6 is 0.5 to 1 times the pipe diameter. The distance between two adjacent baffles 6 should not be too large or too small. If it is too large, the flow obstruction effect will be insignificant and the battery leaching liquid will not be able to make small-amplitude reciprocating movements between the adjacent baffles 6, which is not conducive to the uniform distribution of precipitation. If it is too small, it will affect the flow of the battery leaching liquid, resulting in excessive resistance and increased energy consumption.

[0097] Specifically, the distance between two adjacent baffles 6 can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1 times the pipe diameter.

[0098] Preferably, the area of ​​the flow passage 61 on the baffle 6 is 60% to 80% of the flow cross-sectional area of ​​the impurity removal reactor 1. The area of ​​the flow passage 61 should not be too large or too small. If it is too large, the flow obstruction effect will be insignificant. If it is too small, it will seriously affect the normal flow of the battery leaching solution and easily cause an excessive difference in the flow rate of the battery leaching solution before and after the baffle 6, thus affecting the overall impurity removal effect.

[0099] Specifically, the area of ​​the flow passage 61 on the baffle 6 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, or 80% of the flow cross-sectional area of ​​the impurity removal reactor 1.

[0100] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A system for removing impurities from battery leaching solution, used to remove iron and aluminum impurities from the battery leaching solution, characterized in that, include: The impurity removal reactor (1) includes multiple reaction sections, and adjacent reaction sections are connected by U-shaped bends (15) so that the impurity removal reactor (1) extends upward in a continuous S-shape, and the pH range within the multiple reaction sections is continuous and increases sequentially so that the iron impurities and the aluminum impurities precipitate in stages, and each reaction section is provided with a filter assembly (7) at the end. A feeding assembly is provided at the starting end of the impurity removal reactor (1) to feed the impurity removal reactor (1) so that the battery leachate passes through multiple reaction sections in sequence.

2. The battery leaching solution purification system according to claim 1, characterized in that, The impurity removal reactor (1) comprises four reaction sections, and along the flow direction of the battery leachate, the pH values ​​of the four reaction sections are pH1, pH2, pH3, and pH4, respectively, and 2.8 ≤ pH1 < 3, 3 ≤ pH2 < 3.5, 3.5 ≤ pH3 < 4, and 4 ≤ pH4 < 4.

5.

3. The battery leaching solution purification system according to claim 2, characterized in that, Of the four reaction sections, the first two are controlled at 50°C to 70°C, and the latter two are controlled at 80°C to 100°C.

4. The impurity removal system for battery leachate according to claim 1, characterized in that, Each of the reaction sections is provided with a pH control component (9), which includes an alkali supply head (91) and a pH sensor (92). The alkali supply head (91) is used to supply alkali to the reaction section to control the pH value in the reaction section. The pH sensor (92) is used to detect the pH value in the reaction section. Along the flow direction of the battery leaching solution, the alkali supply head (91) is located upstream of the pH sensor (92).

5. The battery leaching solution purification system according to claim 1, characterized in that, Vibration is applied to the battery leachate in the impurity removal reactor (1), the feeding assembly performs pulsating feeding, and the feeding pulsation frequency of the battery leachate is the same as the vibration frequency of the battery leachate.

6. The battery leaching solution purification system according to claim 5, characterized in that, The impurity removal system further includes a vibration generator (51) connected to the starting end of the impurity removal reactor (1). The vibration generator (51) is used to apply vibration to the battery leachate in the impurity removal reactor (1), and the vibration direction is the same as the flow direction of the battery leachate; and / or, The feeding assembly includes a diaphragm plunger pump, which drives the flow of the battery leaching solution.

7. The battery leaching solution purification system according to claim 1, characterized in that, The filter assembly (7) includes two automatic backwash filters, both of which are connected to the end of the corresponding reaction section, and the two automatic backwash filters work alternately, automatically switching backwash by pressure difference or timed trigger.

8. The battery leachate removal system according to claim 1, characterized in that, Each reaction section is provided with multiple baffles (6), and the baffles (6) have flow holes (61).

9. The battery leaching solution purification system according to claim 8, characterized in that, The area of ​​the flow passage (61) is 60% to 80% of the flow cross-sectional area of ​​the impurity removal reactor (1).

10. A method for removing impurities from battery leachate, characterized in that, The method for removing iron and aluminum impurities from battery leaching solutions includes: The battery leachate is fed into a purification reactor (1) having multiple sequentially connected reaction sections, and the battery leachate is passed through the multiple reaction sections in sequence, with the pH value of the multiple reaction sections increasing sequentially to cause the iron impurities and the aluminum impurities to precipitate in stages; After the precipitates generated in each reaction section are removed by filtration at the end of the reaction section, the battery leachate then enters the next reaction section. Each reaction section uses PID control to regulate the amount of alkali added, thus maintaining the pH value of that section.

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