Lithium precipitation mother liquor recycling system

Abstract

The utility model relates to lithium sink mother liquor recycling technical field, specifically disclose a lithium sink mother liquor recycling system, including the lithium sink mother liquor storage tank, neutralization device, filtering equipment, evaporator and centrifugal device connected in proper order through pipeline, the solid phase recovery device is connected to the solid phase outlet of centrifugal device, and the liquid phase recovery device is connected to the liquid phase outlet of centrifugal device, and the neutralization device includes neutralization jar, and the top of neutralization jar is provided with primary lithium sink mother liquor feeding port and sulfuric acid feeding port, and the sulfuric acid feeding port is connected with sulfuric acid storage tank through sulfuric acid pump, and the bottom of primary lithium sink mother liquor feeding port is connected with first spiral dispersion feeding pipe, and the bottom of sulfuric acid feeding port is connected with second spiral dispersion feeding pipe, and the pH monitor is arranged in neutralization jar, and the outside of neutralization jar is provided with temperature control jacket, and the circulating cooling water is circulated in temperature control jacket. The system can reduce the addition of auxiliary materials, reduce energy consumption, improve the resource utilization rate and economic benefit of lithium carbonate production.

Description

Technical Field

[0001] This utility model relates to the field of lithium precipitation mother liquor recycling technology, and specifically discloses a lithium precipitation mother liquor recycling system. Background Technology

[0002] Lithium carbonate, a key raw material for lithium-ion battery cathode materials, has attracted much attention regarding its preparation process. Lithium precipitation is a core step in lithium carbonate production, aiming to precipitate lithium ions from a lithium-containing solution as lithium carbonate. However, the resulting mother liquor still contains a significant concentration of lithium ions; direct discharge of this mother liquor would result in a substantial loss of valuable lithium resources and increase environmental pollution. Therefore, efficient recovery of lithium from the mother liquor has become an indispensable part of the lithium carbonate production process.

[0003] Currently, the sulfuric acid acidification method is commonly used in industry to recover lithium from lithium precipitation mother liquor. This method involves adding sulfuric acid to the mother liquor, which reacts with residual carbonate ions to generate carbon dioxide gas, thereby disrupting the precipitation equilibrium of lithium carbonate and allowing lithium ions to re-enter the solution. After filtration to remove insoluble matter, the solution is then separated from the lithium-rich solution through evaporation, concentration, and centrifugation. Finally, the lithium-rich solution is returned to the system for re-precipitation, achieving the goal of lithium resource recovery.

[0004] However, this traditional process has significant drawbacks: First, during the addition of sulfuric acid, an excess of sulfuric acid is often used to ensure complete removal of carbonate ions. This excess sulfuric acid leads to an excessively low pH value in the mother liquor, which is detrimental to subsequent processing. Therefore, it is necessary to add alkaline substances such as sodium hydroxide to adjust the pH, thereby increasing the consumption of auxiliary raw materials such as sodium hydroxide and driving up production costs. Second, during the pH adjustment process, sulfuric acid reacts with sodium hydroxide to generate additional sodium sulfate, resulting in a significant increase in the yield of the byproduct sodium sulfate. The increased sodium sulfate yield directly increases the load on the evaporation and concentration process, requiring the evaporation of more water to achieve salt crystallization and separation, thus significantly increasing the system's energy consumption and operating costs, and reducing the economic viability and sustainability of the entire recovery process. In summary, while existing lithium precipitation mother liquor recovery processes achieve lithium recovery, they suffer from problems such as high auxiliary material consumption, large amounts of byproduct salt, and high energy consumption. Utility Model Content

[0005] The purpose of this invention is to provide a lithium precipitation mother liquor recycling system, which can reduce the addition of auxiliary materials, reduce energy consumption, and improve the resource utilization rate and economic benefits of lithium carbonate production.

[0006] This utility model is achieved through the following technical solution: A lithium precipitation mother liquor recycling system includes a lithium precipitation mother liquor storage tank, a neutralization device, a filtration device, an evaporation device, and a centrifuge device connected in sequence by pipelines. The solid phase outlet of the centrifuge device is connected to a solid phase recovery device, and the liquid phase outlet of the centrifuge device is connected to a liquid phase recovery device. The neutralization device includes a neutralization tank. The top of the neutralization tank has a primary lithium precipitation mother liquor inlet and a sulfuric acid inlet. The sulfuric acid inlet is connected to a sulfuric acid storage tank via a sulfuric acid pump. The bottom of the primary lithium precipitation mother liquor inlet is connected to a first spiral dispersion feeding pipe, and the bottom of the sulfuric acid inlet is connected to a second spiral dispersion feeding pipe. A pH monitor is installed inside the neutralization tank, and a temperature control jacket is installed on the outside of the neutralization tank. Circulating cooling water flows through the temperature control jacket.

[0007] Furthermore, both the first spiral dispersing feed pipe and the second spiral dispersing feed pipe are provided with multiple spray holes.

[0008] Furthermore, a temperature monitoring device is also installed inside the neutralization tank.

[0009] Furthermore, the neutralization tank has an exhaust port at the top and a stirring paddle inside.

[0010] Furthermore, the filtration device is a filter press.

[0011] Furthermore, the evaporation device includes at least one flash tank, the inlet of which is connected to the neutralization tank, the outlet of which is connected to a vapor-liquid separator, and the outlets of both the flash tank and the vapor-liquid separator are connected to the inlet of the centrifuge device.

[0012] Furthermore, the solid phase recovery device includes a dryer.

[0013] Furthermore, the liquid phase recovery device includes a mixing tank, a filter press, a lithium precipitation tank, a centrifuge, and a dryer connected in sequence. The top of the mixing tank is provided with a primary lithium precipitation mother liquor inlet and a sodium precipitation mother liquor inlet. The sodium precipitation mother liquor inlet is connected to the liquid phase outlet of the centrifuge device, and the outlet of the centrifuge is connected to the lithium precipitation mother liquor storage tank.

[0014] The technical solution of this utility model has at least the following advantages and beneficial effects: In this invention, the pH of the neutralization tank is adjusted by adjusting the mother liquor of the primary lithium precipitation process, without using sodium hydroxide. A portion of bicarbonate is retained in the neutralized clear liquid, so that lithium carbonate will not saturate and precipitate during the sodium evaporation process, thus increasing lithium loss. This reduces the consumption of sulfuric acid, sodium hydroxide, and sodium carbonate, reduces the amount of water evaporated, and achieves the purpose of reducing the addition of auxiliary materials and reducing energy consumption, thereby improving the resource utilization rate and economic benefits of lithium carbonate production.

[0015] A pH monitor allows for real-time monitoring of the pH within the neutralization tank, facilitating control of the addition of sulfuric acid or primary lithium precipitation mother liquor and improving the neutralization effect. The first and second spiral dispersive feed pipes enhance the uniformity of the addition of primary lithium precipitation mother liquor and sulfuric acid, accelerating the neutralization process. A temperature control jacket regulates the temperature within the neutralization tank, preventing boiling and splashing, controlling the stable release of CO2 gas, reducing acid mist, and promoting the formation of large, easily filterable calcium sulfate crystals, thus increasing the filtration rate and reducing lithium entrainment loss. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the lithium precipitation mother liquor recycling system provided in Embodiment 1 of this utility model.

[0018] Attached reference numerals: 1-Lithium precipitation mother liquor storage tank, 2-Neutralization tank, 3-Filtering device, 4-Flash tank, 5-Vacuum-liquid separator, 6-Centrifuge device, 7-Dryer I, 8-Blending tank, 9-Filter press, 10-Lithium precipitation tank, 11-Centrifuge, 12-Dryer II, 13-Primary lithium precipitation mother liquor feed port, 14-Sulfuric acid feed port, 15-Sulfuric acid pump, 16-Sulfuric acid storage tank, 17-First spiral dispersion feed pipe, 18-Second spiral dispersion feed pipe, 19-pH monitor, 20-Temperature monitor, 21-Agitator, 22-Temperature control jacket, 23-Exhaust port. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this utility model, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this utility model and simplifying the description, 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, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] Example 1 Reference Figure 1 This embodiment provides a lithium precipitation mother liquor recycling system, including a lithium precipitation mother liquor storage tank 1, a neutralization device, a filtration device 3, an evaporation device and a centrifuge device 6 connected in sequence by pipelines. The solid phase outlet of the centrifuge device 6 is connected to a solid phase recovery device, and the liquid phase outlet of the centrifuge device 6 is connected to a liquid phase recovery device. The neutralization device includes a neutralization tank 2. The top of the neutralization tank 2 is provided with a primary lithium precipitation mother liquor inlet 13 and a sulfuric acid inlet 14. The sulfuric acid inlet 14 is connected to a sulfuric acid storage tank 16 via a sulfuric acid pump 15. The bottom of the primary lithium precipitation mother liquor inlet 13 is connected to a first spiral dispersion feeding pipe 17, and the bottom of the sulfuric acid inlet 14 is connected to a second spiral dispersion feeding pipe 18. A pH monitor 19 is installed inside the neutralization tank 2, and a temperature control jacket 22 is installed on the outside of the neutralization tank 2. Circulating cooling water flows through the temperature control jacket 22.

[0024] The pH of the neutralization tank 2 in the primary lithium precipitation mother liquor is adjusted back to neutralization unit without the use of sodium hydroxide. A portion of bicarbonate is retained in the neutralized clear liquid. During the evaporation and sodium precipitation process, lithium carbonate will not saturate and precipitate, increasing lithium loss. This can reduce the consumption of sulfuric acid, sodium hydroxide, and sodium carbonate, reduce the amount of water evaporated, and achieve the purpose of reducing the addition of auxiliary materials and reducing energy consumption, thereby improving the resource utilization rate and economic benefits of lithium carbonate production.

[0025] The pH monitor 19 allows for real-time monitoring of the pH within the neutralization tank 2, facilitating control of the addition of sulfuric acid or primary lithium precipitation mother liquor and improving the neutralization effect of the lithium precipitation mother liquor. The first spiral dispersing feed pipe 17 and the second spiral dispersing feed pipe 18 enhance the uniformity of the addition of primary lithium precipitation mother liquor and sulfuric acid, accelerating the neutralization process. The temperature control jacket 22 regulates the temperature within the neutralization tank 2, preventing solution boiling and splashing, controlling the stable release of CO2 gas, reducing acid mist, and promoting the formation of large, easily filterable calcium sulfate crystals, thereby increasing the filtration rate and reducing lithium entrainment loss.

[0026] The following reaction occurs within the neutralization apparatus:

[0027]

[0028] The purpose of sulfuric acid regulation (acidification) is to remove excess carbonate (CO3) ions from the mother liquor. 2- ) is converted into carbon dioxide (CO) 2 The gas is released, and the remaining lithium carbonate is converted into soluble lithium sulfate. This process introduces sulfate ions (SO4). 2- ), and the calcium (Ca) inherent in the mother liquor 2+ The lithium sulfate precipitate precipitates through an ionic reaction. Therefore, passing the neutralized lithium mother liquor through filtration device 3 removes calcium sulfate, gypsum, and other insoluble impurities. This significantly reduces the formation of a hard, dense scale layer on the inner wall of the evaporator, ensuring heat transfer efficiency and extending cleaning cycles and equipment lifespan. Furthermore, it yields a pure lithium-containing solution, facilitating efficient subsequent recovery of high-purity lithium products. Centrifugation after sodium evaporation separates the lithium-containing solution from the sodium sulfate crystals, facilitating the recovery of both sodium sulfate and lithium from the lithium-containing solution.

[0029] The following reaction occurs inside the evaporator:

[0030] In a specific embodiment, both the first spiral dispersing feed pipe 17 and the second spiral dispersing feed pipe 18 are provided with multiple spray holes. The spray holes can uniformly spray the primary lithium precipitation mother liquor and sulfuric acid into the solution, accelerating the neutralization speed and improving the neutralization effect.

[0031] In a specific implementation, a temperature monitor 20 is also installed inside the neutralization tank 2. The temperature monitor 20 can detect the temperature inside the neutralization tank 2 in real time, controlling the temperature at a low level (e.g., 50-70℃). This allows operators to slowly and controllably add sulfuric acid, ensuring a stable reaction, smooth escape of CO2 gas, avoiding the risk of overflow, and thus guaranteeing the complete decomposition of carbonate ions. Calcium sulfate (gypsum) forms different crystal forms and morphologies of precipitates at different temperatures. At low temperatures (<80℃): it tends to form larger, more regular, flaky crystals. These crystals settle quickly, have good filtration performance, and form filter cakes with high porosity, making them easier to wash and separate, significantly improving filtration efficiency and reducing lithium loss from the filter cake. If the acidification temperature is too high, directly entering the evaporation section will increase the initial load on the evaporation unit. By controlling the acidification reaction at a moderate temperature, the burden on subsequent cooling can be reduced.

[0032] In a specific embodiment, the neutralization tank 2 has an exhaust port 23 at its top, and an agitator 21 is provided inside the neutralization tank 2. The exhaust port 23 can discharge the gas inside the neutralization tank 2, and the agitator 21 can accelerate the neutralization process.

[0033] In a specific embodiment, the filtration device 3 is a filter press.

[0034] In a specific embodiment, the evaporation device includes at least one flash tank 4. The inlet of the flash tank 4 is connected to the neutralization tank 2, and the outlet of the flash tank 4 is connected to a vapor-liquid separator 5. Both the liquid outlet of the flash tank 4 and the liquid outlet of the vapor-liquid separator 5 are connected to the inlet of the centrifuge device 6. The filtered lithium precipitation mother liquor is fed into the flash tank 4 for flash evaporation. The flashed water vapor enters the vapor-liquid separator 5 for gas-liquid separation. The concentrated mother liquor after flash evaporation is then sent to the centrifuge device 6 to separate solid sodium sulfate. The liquid phase is sent to the mixing tank 8 and the primary lithium precipitation mother liquor for mixing to facilitate a secondary lithium precipitation operation. The liquid phase from the vapor-liquid separator 5 is sent to the centrifuge device 6.

[0035] In a specific embodiment, the solid phase recovery device includes a dryer 7. The dryer 7 dries the sodium sulfate separated by the centrifuge 6 to obtain anhydrous sodium sulfate.

[0036] In a specific embodiment, the liquid phase recovery device includes a mixing tank 8, a filter press 9, a lithium precipitation tank 10, a centrifuge 11, and a dryer 12 connected in sequence. The top of the mixing tank 8 is provided with a primary lithium precipitation mother liquor inlet and a sodium precipitation mother liquor inlet. The sodium precipitation mother liquor inlet is connected to the liquid phase outlet of the centrifuge 6, and the outlet of the centrifuge 11 is connected to the lithium precipitation mother liquor storage tank 1. The liquid phase separated by the centrifuge 6 enters the mixing tank 8, and the primary lithium precipitation mother liquor is added to the mixing tank 8 for mixing. After filtration, lithium precipitation, centrifugation, and drying, industrial-grade lithium carbonate product can be obtained. At the same time, the secondary lithium precipitation mother liquor separated by the centrifuge 11 can be directly sent to the lithium precipitation mother liquor storage tank 1 for recycling, that is, used to dissolve the next batch of crude lithium carbonate and prepare LiHCO3 solution. This can greatly reduce the consumption of fresh water and the discharge of wastewater, realizing closed-loop production.

[0037] The following reaction occurs inside the mixing tank:

[0038] The processing procedure of this utility model is as follows: The lithium precipitation mother liquor is transported from the lithium precipitation mother liquor storage tank 1 to the neutralization tank 2 of the neutralization device. The sulfuric acid pump 15 feeds sulfuric acid from the sulfuric acid storage tank 16 into the neutralization tank 2 through the sulfuric acid feed port 14. The sulfuric acid is then sprayed into the lithium precipitation mother liquor through the spray holes of the second spiral dispersion feed pipe 18, and the neutralization reaction is carried out by stirring with the agitator 21. When the pH monitor 19 detects a low pH, primary lithium precipitation mother liquor is introduced through the primary lithium precipitation mother liquor feed port 13 to neutralize excess sulfuric acid. The neutralized lithium precipitation mother liquor is filtered by the filter device 3 to remove impurities such as gypsum, and then enters the flash evaporator 4 for flash evaporation. The flashed water vapor enters the vapor-liquid separator 5 for gas-liquid separation. The concentrated mother liquor after flash evaporation is then sent to the centrifuge device 6 to separate solid sodium sulfate. The solid sodium sulfate is dried in a dryer 7 to obtain anhydrous sodium sulfate. The liquid phase is fed into the mixing tank 8 and the primary lithium precipitation mother liquor for mixing. After filtration, lithium precipitation, and centrifugation, the solid separated by centrifuge 11 is dried by dryer 12 to obtain industrial-grade lithium carbonate product. The secondary lithium precipitation mother liquor separated by centrifuge 11 can be directly sent to the lithium precipitation mother liquor storage tank 1 for recycling.

[0039] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A lithium sink liquor recycling system, characterized by, The system includes a lithium precipitation mother liquor storage tank, a neutralization device, a filtration device, an evaporation device, and a centrifuge device connected in sequence by pipelines. The solid phase outlet of the centrifuge device is connected to a solid phase recovery device, and the liquid phase outlet of the centrifuge device is connected to a liquid phase recovery device. The neutralization device includes a neutralization tank. The top of the neutralization tank has a primary lithium precipitation mother liquor inlet and a sulfuric acid inlet. The sulfuric acid inlet is connected to a sulfuric acid storage tank via a sulfuric acid pump. The bottom of the primary lithium precipitation mother liquor inlet is connected to a first spiral dispersion feeding pipe, and the bottom of the sulfuric acid inlet is connected to a second spiral dispersion feeding pipe. A pH monitor is installed inside the neutralization tank, and a temperature control jacket is installed on the outside of the neutralization tank. Circulating cooling water flows through the temperature control jacket.

2. The lithium sink liquor recycling system of claim 1, wherein, Both the first spiral dispersing feed pipe and the second spiral dispersing feed pipe are provided with multiple spray holes.

3. The lithium sink liquor recycling system of claim 1, wherein, The neutralization tank is also equipped with a temperature monitoring instrument.

4. The lithium sink liquor recycling system of claim 1, wherein, The neutralization tank has an exhaust port at the top and a stirring paddle inside.

5. The lithium sink liquor recycling system of claim 1, wherein, The filtration device is a filter press.

6. The lithium sink liquor recycling system of claim 1, wherein, The evaporation device includes at least one flash tank, the inlet of which is connected to the neutralization tank, the outlet of which is connected to a vapor-liquid separator, and the outlets of both the flash tank and the vapor-liquid separator are connected to the inlet of the centrifuge device.

7. The lithium sink liquor recycling system of claim 1, wherein, The solid phase recovery device includes a dryer.

8. The lithium sink liquor recycling system of claim 1, wherein, The liquid phase recovery device includes a mixing tank, a filter press, a lithium precipitation tank, a centrifuge, and a dryer connected in sequence. The top of the mixing tank is provided with a primary lithium precipitation mother liquor inlet and a sodium precipitation mother liquor inlet. The sodium precipitation mother liquor inlet is connected to the liquid phase outlet of the centrifuge device, and the outlet of the centrifuge is connected to the lithium precipitation mother liquor storage tank.

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