A process for the preparation of battery grade lithium hydroxide

Abstract

The application relates to the technical field of lithium hydroxide production, and discloses a processing technology for preparing battery-grade lithium hydroxide, which comprises the following steps: lithium ore is crushed to a reasonable particle size and then is sent into a roasting furnace, lithium ore is destroyed through high-temperature roasting, the roasted ore clinker is sent into a reaction kettle, sulfuric acid solution is added to carry out acidification reaction, then water is added to carry out leaching, and a crude leaching solution containing lithium sulfate is obtained. The application is provided with a sealing element, the large contact area design of the L-shaped sealing strip improves the reliability of the primary sealing, the cooperation of the elastic pressing strip and the spring can effectively compensate for the slight deformation in the equipment operation process, the stability of the sealing performance is ensured, the double-sealing structure can effectively prevent the leakage of the heat exchange medium, the problems of resource waste, environmental pollution and equipment damage caused by medium leakage are avoided, the influence of cross contamination of different media on product quality is also avoided.

Description

Technical Field

[0001] This invention relates to the field of lithium hydroxide production technology, and more specifically to a processing technology for preparing battery-grade lithium hydroxide. Background Technology

[0002] Battery-grade lithium carbonate / lithium hydroxide, as part of the cathode material, participates in the charge-discharge reaction of the battery, storing and releasing electrical energy, and is a key material used in the manufacture of lithium-ion batteries. With the rise of the lithium-ion battery new energy market, its market demand is also growing rapidly. Currently, my country's ore-based lithium hydroxide synthesis technology dominates in terms of both process and production capacity, while brine-based lithium extraction technology is developing relatively slowly. There are two main processes for ore-based lithium extraction: one involves roasting, acidifying, leaching, and causticizing lithium ore to obtain a lithium hydroxide solution, which is then processed through carbonization precipitation, dehydration, purification, drying, crushing, demagnetization, and packaging. The other process involves roasting, acidifying, and leaching lithium ore to obtain a lithium sulfate solution, which is then processed through carbonization precipitation, dehydration, purification, drying, crushing, demagnetization, and packaging.

[0003] The current lithium precipitation process involves first subjecting a mother liquor containing lithium hydroxide and sodium sulfate to deep cooling to precipitate and separate the sodium sulfate. The product is then heated, concentrated using MVR (Mechanical Vapor Reduction), filtered, and washed to obtain battery-grade lithium hydroxide. However, this process consumes significant amounts of refrigerant and steam during the cooling and heating stages without waste heat recovery, and produces low-calorific-value intermediates. The process is intermittent, and the product's impurity content fluctuates greatly, making it difficult to meet requirements. Purification is generally necessary to remove impurities and satisfy quality standards, resulting in low production efficiency. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a processing technology for preparing battery-grade lithium hydroxide, which can effectively solve the problems of high energy consumption due to lack of waste heat recovery in the lithium precipitation process, large fluctuations in impurity content due to intermittent production, the need for purification treatment, and low production efficiency in the existing technology.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a processing method for preparing battery-grade lithium hydroxide, comprising:

[0007] S1. Preparation of lithium sulfate solution: After crushing lithium ore to a reasonable particle size, it is fed into a roasting furnace. The high-temperature roasting process destroys the crystal structure of the lithium ore. The roasted ore clinker is then fed into a reaction vessel, where sulfuric acid solution is added for acidification. Water is then added to the acidification reaction system for leaching to obtain a crude leaching solution containing lithium sulfate. Suspended particles and soluble impurities in the crude leaching solution are removed through sedimentation, filtration, and impurity removal processes to finally obtain a pure lithium sulfate solution.

[0008] S2. Preparation of lithium hydroxide monohydrate: A pure lithium sulfate solution is fed into a causticizing reactor, and a 50% sodium hydroxide solution is added to carry out the causticizing reaction to generate lithium hydroxide monohydrate and sodium sulfate. After the reaction is completed, the solution is filtered to obtain a causticizing solution containing sodium sulfate and lithium hydroxide monohydrate.

[0009] S3. Multi-stage cooling: The causticizing liquid is sent into a multi-stage cooling system for step cooling to form a slurry containing a large amount of sodium sulfate crystals;

[0010] S4. Solid-liquid separation: The slurry is fed into a centrifugal separator. The resulting solid sodium sulfate crystals are transported to the sodium sulfate workshop for resource recovery. The resulting low-temperature filtered mother liquor is returned to S3 as a cold source to pre-cool the newly fed causticizing liquid, thus completing the closed loop of cold energy recovery.

[0011] S5. Waste heat recovery: After the low-temperature filtered mother liquor completes the heat exchange in S3, it immediately enters the primary filtered mother liquor-secondary condensate heat exchanger to participate in the waste heat recovery of the condensate.

[0012] S6. Preparation of battery-grade lithium hydroxide: The filtered mother liquor after temperature rise is directly sent to the MVR concentration system. The concentrated liquid is filtered, washed and dried to finally obtain battery-grade lithium hydroxide product.

[0013] Furthermore, the multi-stage cooling process sequentially includes multiple cooling steps such as primary precooling, secondary precooling, tertiary primary crystallization cooling, and quaternary cryogenic crystallization.

[0014] Furthermore, the first-stage precooling specifically includes: sending the causticizing liquid into a circulating water-causticizing liquid heat exchanger to exchange heat indirectly with the circulating water;

[0015] The secondary precooling specifically includes: sending the causticized liquid after primary precooling into a filtration mother liquor-causticized liquid heat exchanger to indirectly exchange heat with the low-temperature filtration mother liquor from the subsequent solid-liquid separation process;

[0016] The three-stage primary crystallization cooling specifically includes: sending the causticizing liquid after the second-stage precooling into a primary crystallizer for indirect heat exchange with chilled water;

[0017] The fourth-stage cryogenic crystallization specifically includes: sending the causticizing liquid containing crystal nuclei after cooling from the third-stage primary crystallization into a cryogenic crystallization tank, where it continues to exchange heat indirectly with chilled water to obtain the slurry containing a large amount of sodium sulfate crystals.

[0018] Furthermore, the filtered mother liquor-causticizing liquid heat exchanger includes a heat exchange body, and a support base is provided at the bottom of the heat exchange body;

[0019] The heat exchange body includes a frame, plates are fixedly connected to both ends of the frame, an isolation plate is provided in the middle of the plate, and cavities are symmetrically arranged inside the plate with the frame as the boundary. Heat exchange pipes are provided on the inner side of each cavity.

[0020] One end of the heat exchange pipe is fixedly connected to the inlet pipe, and the other end of the heat exchange pipe is fixedly connected to the outlet pipe;

[0021] The heat exchange pipe is fitted with a sealing element at the connection between the heat exchange pipe and the inlet pipe to ensure a tight seal.

[0022] Furthermore, the sealing element includes an inner fixing ring that connects the heat exchange pipe and the inlet pipe, and the inner wall of the inner fixing ring is provided with an L-shaped sealing strip.

[0023] Furthermore, the sealing element also includes a sealing tube disposed outside the inner fixing ring, the inner wall of the sealing tube having a channel, and the inner wall of the channel having an elastic pressure strip disposed circumferentially.

[0024] Furthermore, a fixed rod is slidably connected to the middle of the elastic pressure strip. The fixed rod is embedded in the inner wall of the channel, and a spring is sleeved on the outer wall of the fixed rod. The outer wall of the spring is elastically connected to the inner wall of the elastic pressure strip.

[0025] Furthermore, a turbulence column is provided on the inner wall of the end of the heat exchange pipe near the inlet pipe. The turbulence column adopts an arc-shaped design and is evenly arranged circumferentially on the inner wall of the heat exchange pipe.

[0026] Furthermore, a guide plate is fixedly connected to the side of the plate near the frame, and the outer wall of the guide plate adopts a tapered design.

[0027] The plate has corrugations on the other side near the frame, and the corrugations are designed in a herringbone pattern.

[0028] Furthermore, the primary condensate from the secondary steam condensation of the MVR concentration process first enters a circulating water-primary condensate heat exchanger to exchange heat indirectly with the circulating water.

[0029] The cooled primary condensate then enters the filtered mother liquor-secondary condensate heat exchanger for indirect heat exchange with the filtered mother liquor.

[0030] The technical solution provided by this invention has the following advantages compared with the prior art:

[0031] This invention incorporates sealing elements, constructing a complete sealing and protection system from the initial seal formed by the inner fixing ring and L-shaped sealing strip in the inner layer, to the elastic seal formed by the outer sealing tube, elastic pressure strip, and spring. The large contact area design of the L-shaped sealing strip improves the reliability of the initial seal, while the cooperation between the elastic pressure strip and the spring effectively compensates for minor deformations during equipment operation, ensuring the stability of the sealing performance. This dual-sealing structure effectively prevents leakage of the heat exchange medium, avoiding problems such as resource waste, environmental pollution, and equipment damage caused by medium leakage, while also preventing the impact of cross-contamination between different media on product quality.

[0032] This invention features an isolation plate that divides the interior of the plate into two independent chambers. This design allows the heat exchanger to simultaneously adapt to two different heat exchange conditions: heat recovery of cold energy between the causticizing liquid and the filtered mother liquor, and waste heat recovery of the filtered mother liquor and the primary condensate. This design eliminates the need for separate heat exchangers for each condition, significantly reducing the equipment's footprint and investment costs, while also simplifying the process and reducing the complexity of piping connections. The two independent chambers effectively prevent cross-contamination between different heat exchange media, ensuring the purity of the heat exchange media and thus guaranteeing the quality of subsequent products. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0034] Figure 1 This is a schematic diagram of the processing technology of an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of the filtrated mother liquor-causticizing liquid heat exchanger according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the heat exchanger body structure in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the inlet pipe connection structure according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic cross-sectional view of the sealing element structure according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the heat exchange pipeline structure according to an embodiment of the present invention;

[0040] Figure 7This is a schematic diagram of the plate structure according to an embodiment of the present invention.

[0041] The labels in the diagram represent: 1. Heat exchanger body; 11. Plate; 112. Guide plate; 113. Corrugated plate; 12. Frame; 13. Isolation plate; 14. Heat exchange pipe; 141. Turbulence column; 15. Inlet pipe; 16. Outlet pipe; 17. Seal; 171. Sealing pipe; 172. Channel; 173. Elastic pressure strip; 174. Spring; 175. Inner fixing ring; 176. Sealing strip; 2. Support base. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] The present invention will be further described below with reference to embodiments.

[0044] Example:

[0045] Please see Figures 1-7 This invention provides a processing technology solution for preparing battery-grade lithium hydroxide, comprising the following steps:

[0046] S1. Preparation of lithium sulfate solution: After crushing lithium ore to a reasonable particle size, it is fed into a roasting furnace. The high-temperature roasting process destroys the crystal structure of the lithium ore. The roasted ore clinker is then fed into a reaction vessel, where sulfuric acid solution is added for acidification. Water is then added to the acidification reaction system for leaching to obtain a crude leaching solution containing lithium sulfate. Suspended particles and soluble impurities in the crude leaching solution are removed through sedimentation, filtration, and impurity removal processes to finally obtain a pure lithium sulfate solution.

[0047] S2. Preparation of lithium hydroxide monohydrate: A pure lithium sulfate solution is fed into a causticizing reactor, and a 50% sodium hydroxide solution is added to carry out the causticizing reaction to generate lithium hydroxide monohydrate and sodium sulfate. After the reaction is completed, the solution is filtered to obtain a causticizing solution containing sodium sulfate and lithium hydroxide monohydrate.

[0048] S3. Multi-stage cooling: The causticizing liquid is sent into a multi-stage cooling system for step cooling to form a slurry containing a large amount of sodium sulfate crystals;

[0049] Multi-stage cooling sequentially includes multiple cooling steps: primary precooling, secondary precooling, tertiary primary crystallization cooling, and quaternary cryogenic crystallization.

[0050] First-stage precooling: The causticizing liquid is sent into the circulating water-causticizing liquid heat exchanger to exchange heat indirectly with the circulating water, and the temperature drops from 60℃ to 45℃. This step uses low-energy circulating water to handle the first round of temperature drop, avoiding the direct use of high-energy chilled water and reducing the load on subsequent cryogenic processes.

[0051] Secondary precooling: The 45°C causticizing liquid is fed into the filtrate mother liquor-causticizing liquid heat exchanger, where it indirectly exchanges heat with the low-temperature filtrate mother liquor from the subsequent centrifugal separation process. The temperature of the causticizing liquid drops to 35°C. This step achieves cold energy recovery, transferring the cold energy of the low-temperature filtrate mother liquor to the newly fed causticizing liquid, further reducing the amount of chilled water used.

[0052] Three-stage primary crystallization cooling: The causticizing liquid at 35°C is sent into the primary crystallizer and indirectly heats it with the chilled water. The temperature drops to 25°C. At this point, the sodium sulfate in the causticizing liquid reaches a supersaturated state and begins to precipitate fine crystal nuclei, laying the foundation for subsequent deep crystallization.

[0053] Fourth-stage cryogenic crystallization: The causticizing liquid containing crystal nuclei at 25°C is sent into the cryogenic crystallization tank and continues to exchange heat indirectly with the chilled water until the temperature drops to -5°C; the low temperature environment causes most of the sodium sulfate crystals in the causticizing liquid to precipitate deeply, forming a slurry containing a large amount of sodium sulfate crystals.

[0054] S4. Solid-liquid separation: The sodium sulfate slurry at -5℃ is fed into a horizontal screw discharge centrifuge for centrifugal separation. The solid sodium sulfate crystals obtained are transported to the sodium sulfate workshop for resource utilization. The low-temperature filtered mother liquor obtained is returned to the secondary pre-cooling process of S3 as a cold source to pre-cool the newly fed causticizing liquid, thus completing the closed loop of cold energy recovery.

[0055] S5. Waste heat recovery: After heat exchange in the secondary pre-cooling process of S3, the temperature of the low-temperature filtered mother liquor rises from -5℃ to 10℃, and then enters the filtered mother liquor-secondary condensate heat exchanger to participate in the waste heat recovery of the primary condensate.

[0056] The secondary steam condensation from the subsequent MVR concentration process, with the initial temperature of the primary condensate at about 80°C, first enters the circulating water-primary condensate heat exchanger, where it indirectly exchanges heat with the circulating water, and the temperature drops from 80°C to 60°C. The waste heat recovered in this step can be used for heat tracing of equipment in the plant area, preheating of materials, and low-grade heat application scenarios.

[0057] The primary condensate at 60°C enters the mother liquor-secondary condensate heat exchanger and indirectly exchanges heat with the mother liquor at 10°C. The temperature of the primary condensate eventually drops to 40°C, and the temperature of the mother liquor rises from 10°C to 20°C after absorbing the residual heat.

[0058] S6. Preparation of battery-grade lithium hydroxide: The filtered mother liquor, heated to 20°C, is directly fed into the MVR concentration system. Since the filtered mother liquor has been heated to 20°C through waste heat recovery, the concentrated liquid undergoes filtration, washing, and drying processes to finally produce battery-grade lithium hydroxide products.

[0059] refer to Figure 2 and Figure 3 The core load-bearing structure of this heat exchanger is the heat exchange body 1, with a support base 2 fixedly installed at its bottom. The support base 2 adopts a frame structure adapted to the contour of the heat exchange body 1 and is tightly connected to the mounting seat at the bottom of the heat exchange body 1 by bolts, providing stable support for the entire equipment and effectively distributing the weight and vibration loads generated during equipment operation. The main structure of the heat exchange body 1 consists of a frame 12, which is made of high-strength alloy material and has a rectangular structure. Plates 11 are fixedly connected to both ends by welding. The plates 11 and the frame 12 form a closed cavity structure, providing a sealed space for the flow and heat exchange of the heat exchange medium. This integrated connection design of the frame 12 and the plates 11 not only ensures the structural strength of the heat exchange body 1 but also effectively avoids the problem of loosening of the connection due to equipment vibration during operation, allowing the equipment to maintain a stable structural form even under long-term continuous operation without the occurrence of component detachment.

[0060] refer to Figure 3 and Figure 4 A partition plate 13 is fixedly installed in the middle of the plate 11. The partition plate 13 extends longitudinally along the plate 11, symmetrically dividing the interior of the plate 11 into two independent cavities with the frame 12 as the boundary. The two cavities are independent and have good sealing performance, preventing media penetration between them. They can each accommodate different heat exchange media, thus enabling synchronous or alternating operation of two different heat exchange conditions within the same equipment. This eliminates the need for additional independent heat exchange equipment for different heat exchange requirements, greatly simplifying the equipment layout of the entire process and making more rational use of the production line space. Heat exchange pipes 14 are evenly arranged inside both independent cavities. The heat exchange pipes 14 adopt a serpentine bend arrangement and are tightly fixed to the inner wall of the plate 11. This design maximizes the contact area between the heat exchange medium and the heat exchange surface, allowing for more efficient heat transfer. One end of the heat exchange pipe 14 is fixedly connected to the inlet pipe 15, and the other end is fixedly connected to the outlet pipe 16. A complete and unobstructed medium flow channel is formed from the inlet to the outlet, which can ensure that the medium participating in the heat exchange flows smoothly inside the pipe and completes the entire heat exchange process smoothly without the problem of medium stagnation or poor flow.

[0061] refer to Figure 3 and Figure 7To further improve the overall heat exchange efficiency of the equipment, a guide plate 112 is fixedly connected to the side of the plate 11 near the frame 12. The outer wall of the guide plate 112 adopts a conical structure design, with the tip of the cone facing the outlet direction of the inlet pipe 15. This unique conical structure can effectively guide and evenly distribute the heat exchange medium entering the cavity, allowing the medium entering the cavity to flow evenly along the conical slope of the guide plate 112 to each heat exchange pipe 14 in the cavity. This fundamentally avoids the local accumulation of heat exchange medium inside the cavity and also eliminates the formation of dead flow zones inside the cavity, ensuring that each heat exchange pipe 14 can participate in the heat exchange operation and improve the overall heat exchange efficiency. At the same time, corrugations 113 are added to the side of the plate 11 near the frame 12. The corrugations 113 adopt a herringbone structure design and are evenly distributed on the inner wall surface of the plate 11 in a regular arrangement. The herringbone corrugated structure 113 can, on the one hand, further increase the heat exchange surface area of ​​the plate 11, allowing more contact points for heat transfer, and on the other hand, it can generate effective turbulence during the flow of the heat exchange medium, which can destroy the laminar boundary layer formed by the medium during the flow and promote the medium to form a turbulent state that is more conducive to heat exchange, thereby further improving the heat exchange efficiency of the equipment and making the transfer of cold and heat more efficient.

[0062] refer to Figure 6 A turbulence-inducing column 141 is fixedly installed on the inner wall of the heat exchange pipe 14 near the inlet pipe 15. The turbulence-inducing column 141 adopts an arc-shaped structure design, and its arc is adapted to the arc of the inner wall of the heat exchange pipe 14, so that it can fit tightly against the inner wall of the pipe and will not form additional protrusions or obstructions inside the pipe. The turbulence-inducing columns 141 are evenly distributed circumferentially along the inner wall of the heat exchange pipe 14. The spacing between two adjacent turbulence-inducing columns 141 has been precisely calculated and designed, so that the spacing is neither too small to excessively obstruct the flow of the medium, nor too large to fail to fully exert the turbulence-inducing effect. When the heat exchange medium enters the heat exchange pipe 14 from the inlet pipe 15, it first comes into contact with the arc-shaped turbulence column 141. Under the obstruction and guidance of the turbulence column 141, the original flow direction of the medium will be reasonably changed, thus forming an irregular vortex motion. This vortex motion state allows the heat exchange medium to have more comprehensive and sufficient contact with the inner wall of the heat exchange pipe 14, which can not only effectively improve the heat exchange efficiency, but also reduce the adhesion and accumulation of crystal particles contained in the heat exchange medium on the inner wall of the pipe, reduce the probability of pipe scaling, and extend the cleaning cycle of the pipe.

[0063] refer to Figure 4 , Figure 5 and Figure 7To fundamentally ensure that the heat exchange medium does not leak during the entire flow and heat exchange process, a sealing element 17 is installed at the connection between the heat exchange pipe 14 and the inlet pipe 15. This sealing element 17 employs a double-layer protection and double-seal design, forming a complete and tight sealing protection system from the inside out, comprehensively eliminating the possibility of medium leakage. The core inner structure of the sealing element 17 is an inner fixing ring 175. The inner fixing ring 175 adopts a ring-shaped structure design, which can be tightly fitted at the connection between the heat exchange pipe 14 and the inlet pipe 15, providing both a stable fixation of the connection position between the two pipes and achieving preliminary sealing protection. On the inner wall of the inner fixed ring 175, there is also an L-shaped sealing strip 176. The sealing strip 176 is made of high-quality elastic and wear-resistant material. Its unique L-shaped structure can form a multi-faceted tight fit with the inner wall of the inner fixed ring 175 and the end face of the pipe interface, effectively increasing the sealing contact area and structurally improving the reliability of the initial seal, so that the inner seal can form a solid anti-leakage barrier.

[0064] A sealing tube 171 is fitted around the outer part of the inner fixing ring 175. The inner wall of the sealing tube 171 fits tightly against the outer wall of the inner fixing ring 175, forming a secondary sealing protection, creating a double protection structure with the inner sealing layer. An annular groove 172 is formed on the inner wall of the sealing tube 171. Elastic pressure strips 173 are evenly arranged circumferentially on the inner wall of the groove 172. A fixing rod is slidably connected to the center of the elastic pressure strip 173, and the fixing rod is securely embedded in the inner wall of the groove 172. The axis of the fixing rod is perpendicular to the axis of the sealing tube 171. A spring 174 is fitted around the outer wall of the fixing rod. One end of the spring 174 is fixedly connected to the inner wall of the groove 172, and the other end is elastically connected to the inner wall of the elastic pressure strip 173. This elastic structural design allows the elastic pressure strip 173 to remain tightly fitted to the outer wall of the inner fixing ring 175 under the elastic support of the spring 174, forming a continuous elastic seal. This effectively compensates for minor structural deformations caused by temperature changes or slight vibrations during equipment operation, ensuring a tight fit of the sealing surface from beginning to end and maintaining stable sealing performance. It prevents seal failure due to deformation during normal equipment operation.

[0065] The heat exchanger's various structural optimizations and special constructions offer corresponding practical advantages. The coordinated design of these structures significantly enhances the overall performance of the equipment. The tight connection between the support base 2 and the heat exchange body 1 effectively distributes the equipment's weight and vibration loads generated during operation, preventing structural deformation or loosening of components due to continuous vibration during long-term, uninterrupted operation. This fundamentally ensures the overall stability of the equipment. The integrated welded connection between the frame 12 and the plates 11 further enhances the overall structural strength of the heat exchange body 1, allowing it to adapt well to different pressure and temperature changes throughout the process. This prevents structural damage due to changes in operating conditions, effectively extending the overall service life of the equipment. Furthermore, the modular structural design of the equipment, with its simple and robust connections between core components, facilitates installation, disassembly, and daily maintenance, significantly reducing the difficulty of later maintenance operations and minimizing manpower and time costs.

[0066] The design of the partition plate 13, which divides the interior of plate 11 into two independent chambers, is one of the core advantages of this heat exchanger. This design allows the heat exchanger to simultaneously adapt to two different heat exchange conditions: cold energy recovery heat exchange between the causticizing liquid and the filtered mother liquor, and waste heat recovery heat exchange between the filtered mother liquor and the primary condensate. This multi-purpose design eliminates the need for separate heat exchange equipment for two different heat exchange requirements, significantly reducing the overall footprint of the equipment, lowering procurement and investment costs, simplifying the overall process flow, reducing the number and complexity of piping connections, and making the layout of the entire production line more compact and rational. The two independent chambers have excellent sealing performance, effectively preventing cross-contamination between different heat exchange media, ensuring the purity of each heat exchange medium from the source. The purity of the medium further guarantees the product quality of subsequent lithium hydroxide preparation processes, avoiding product impurity content exceeding standards due to medium contamination.

[0067] The conical design of the guide plate 112 effectively guides and distributes the heat exchange medium, ensuring its uniform distribution throughout the heat exchange pipes 14. This avoids insufficient heat exchange caused by dead zones in localized flow, allowing each pipe 14 to perform its heat exchange function effectively. The herringbone corrugations 113 on the plate 11 increase the heat exchange surface area and promote turbulence, disrupting the laminar boundary layer and effectively improving heat transfer efficiency. The arc-shaped turbulence columns 141 on the inner wall of the heat exchange pipes 14 further enhance the turbulence effect, ensuring more thorough contact between the medium and the pipe wall, further improving heat exchange efficiency. These heat-enhancing structures work synergistically, progressively improving heat exchange efficiency, ultimately ensuring that the heat exchanger achieves efficient heat exchange within a limited space. This fully meets the efficiency requirements of the entire manufacturing process for cold energy recovery and waste heat utilization, resulting in a significant improvement in energy utilization.

[0068] The dual-seal design of seal 17 is the core guarantee for equipment leakage prevention. From the tight initial seal formed by the inner fixing ring 175 and the L-shaped sealing strip 176, to the elastic compensation seal formed by the outer sealing tube 171, elastic pressure strip 173, and spring 174, a complete sealing protection system without dead angles is constructed. The large contact area design of the L-shaped sealing strip 176 structurally improves the reliability of the initial seal, while the elastic cooperation of the elastic pressure strip 173 and spring 174 can flexibly compensate for various minor deformations during equipment operation, ensuring that the sealing performance remains stable at all times. This dual-seal structure can fundamentally prevent the leakage of heat exchange medium, avoiding the waste of raw material resources caused by medium leakage, eliminating environmental pollution problems caused by leaked media, preventing equipment corrosion and damage caused by leakage, and avoiding the adverse effects of cross-contamination between different media on the final product quality, thus comprehensively ensuring the stability of the process and the quality of the product.

[0069] Meanwhile, all materials selected for the sealing element 17 possess excellent low-temperature resistance, effectively adapting to the low-temperature environment of the mother liquor heat exchange process after filtration. This material-wise avoids the problem of sealing material embrittlement, hardening, and subsequent seal failure caused by low-temperature environments. The elastic structure design composed of the elastic pressure strip 173 and spring 174 can also adapt to the thermal shrinkage deformation of the equipment under low-temperature conditions, ensuring that the sealing surface always maintains a tight fit, further improving the sealing reliability under low-temperature conditions. In addition, the base materials used for the heat exchange pipe 14 and plate 11 have also undergone low-temperature adaptability screening and treatment, maintaining good structural strength and efficient heat exchange performance even in low-temperature working environments. They will not experience material cracking or a decrease in heat exchange efficiency due to excessively low temperatures, ultimately ensuring that the equipment maintains stable operation and good working performance throughout the entire temperature range of the process.

[0070] The filtrate mother liquor-causticizing liquid heat exchanger is a core heat exchange device in the battery-grade lithium hydroxide preparation process. It primarily undertakes two core heat exchange tasks throughout the production process: secondary pre-cooling and cold energy recovery of the causticizing liquid, and waste heat recovery from the primary condensate. The entire usage process and operation steps of this equipment closely align with the overall lithium hydroxide preparation process, with each operational step interconnected and seamlessly integrated with the preceding and following processes. The specific usage process and detailed steps are as follows:

[0071] Before the equipment is officially put into production, a comprehensive and detailed inspection of the entire heat exchanger system is necessary. This is the fundamental prerequisite for ensuring stable operation of the equipment. The inspection mainly focuses on the structural connections and sealing performance of the equipment. First, check whether the connection between the support base 2 and the heat exchange body 1 is firm and whether all connecting bolts are tightened to ensure there is no looseness. Then, check whether there are any defects such as cracks, pinholes, or leaks at the welded joints of the frame 12 and the plate 11, ensuring the sealing and firmness of the welds. Next, check the sealing performance of the isolation plate 13 to confirm that there is no media leakage between the two independent cavities, ensuring the independence of the cavities. At the same time, check whether the connections between the heat exchange pipes 14, the inlet pipe 15, and the outlet pipe 16 are tight, and whether all seals 17 are intact and undamaged, without aging, deformation, or damage that could affect the sealing. In addition, check whether the valves on each pipe are in the correct open and closed state to ensure that the flow channels of the heat exchange medium remain unobstructed. After completing all the inspection work, the heat exchanger system also needs to be purged with nitrogen. The flow of nitrogen will thoroughly remove any remaining impurities and moisture from the pipes, preventing impurities from clogging the pipes during operation and preventing residual moisture from affecting the purity of the heat exchange medium and the heat exchange effect.

[0072] After completing the preliminary preparations, the equipment can be started to enter the cold energy recovery mode of the causticizing liquid secondary precooling. First, the relevant medium transfer pump is started to slowly introduce the low-temperature filtered mother liquor from the centrifugal separation process into the heat exchanger through the inlet pipe 15 of one of the chambers. After entering the inlet pipe 15, the low-temperature filtered mother liquor first flows through the guide plate 112 on the plate 11. Under the guidance and diversion action of the conical guide plate 112, it is evenly distributed into the heat exchange pipes 14 in that chamber. At the same time, the causticizing liquid, which has undergone primary precooling treatment, is synchronously introduced into the heat exchanger through the inlet pipe 15 of the other chamber. Under the guidance of the guide plate 112 of the corresponding chamber, the causticizing liquid is also evenly distributed into the heat exchange pipes 14 in that chamber. The two media are fed into their respective independent chambers and pipes.

[0073] The low-temperature filtered mother liquor and the causticizing liquid flow within their respective heat exchange pipes 14. During this flow, the medium first comes into contact with the arc-shaped turbulence-inducing columns 141 on the inner wall of the heat exchange pipe 14. Under the turbulence of the turbulence-inducing columns 141, the flow state of the medium changes to vortex motion, which allows for more thorough contact between the medium and the inner wall of the heat exchange pipe 14. Simultaneously, the herringbone-shaped corrugations 113 on the inner wall of the plates 11 further enhance the turbulence state of the medium, further improving heat transfer efficiency. The two heat exchange media exchange heat indirectly through the pipe wall of the heat exchange pipe 14 and the plates 11. The heat carried by the causticizing liquid is fully absorbed by the low-temperature filtered mother liquor, thus successfully completing the core operation of cold energy recovery.

[0074] After sufficient heat exchange, the temperature of the causticizing liquid will be significantly reduced, reaching the temperature standard required for process production. It will then be discharged from the heat exchanger through the drain pipe 16 of its corresponding chamber and directly enter the next stage primary crystallizer for further cooling and crystallization. Meanwhile, the low-temperature filtrate mother liquor, after absorbing heat from the causticizing liquid, will have its temperature effectively increased. The heated filtrate mother liquor will be discharged from the heat exchanger through the drain pipe 16 of its corresponding chamber and then enter the subsequent waste heat recovery process to continue participating in the heat exchange operation. Throughout the entire heat exchange process of cold energy recovery, the seals 17 at each pipe connection will consistently provide a stable double seal. The L-shaped sealing strip 176 on the inner wall of the inner fixed ring 175 will tightly fit the pipe interface, forming a solid inner seal. The elastic pressure strip 173 inside the sealing pipe 171, under the elastic action of the spring 174, will always tightly fit against the outer wall of the inner fixed ring 175, flexibly compensating for minor deformations during equipment operation and ensuring no media leakage occurs throughout the process.

[0075] After completing the cold energy recovery operation of the causticizing liquid, the equipment can seamlessly switch to the waste heat recovery mode of the primary condensate. The operation process in this mode is equally simple and smooth. First, the corresponding delivery pump is started to introduce the high-temperature primary condensate from the MVR concentration process into the heat exchanger through the inlet pipe 15 of one of the chambers. This chamber can be shared with the chamber used for the filtered mother liquor in the causticizing liquid pre-cooling mode. The mode switch can be completed simply by switching the pipe valves, without any structural adjustments to the equipment. After entering the chamber, the high-temperature primary condensate is evenly distributed to the various heat exchange pipes 14 in the chamber under the guidance of the guide plate 112. At the same time, the filtered mother liquor, which has been heated after the causticizing liquid pre-cooling mode, is introduced into the heat exchanger through the inlet pipe 15 of the other chamber. The filtered mother liquor is also evenly distributed to the corresponding heat exchange pipes 14 under the guidance of the guide plate 112.

[0076] The high-temperature primary condensate and the heated filtered mother liquor flow separately within their respective heat exchange pipes 14. Under the combined turbulence of the turbulence columns 141 on the inner wall of the heat exchange pipes 14 and the corrugations 113 on the inner wall of the plates 11, both media form a highly efficient heat-exchange turbulent flow state. Subsequently, they exchange heat indirectly through the pipe walls of the heat exchange pipes 14 and the plates 11. The waste heat carried by the high-temperature primary condensate is fully absorbed by the filtered mother liquor, thus successfully completing the cascade utilization of waste heat and effectively recovering and reusing heat that would otherwise be wasted.

[0077] After sufficient waste heat exchange, the temperature of the primary condensate will decrease to the required standard for the process. The cooled primary condensate will be discharged from the heat exchanger through drain pipe 16. After simple treatment, it can be reused as process makeup water, realizing the recycling of water resources. The filtered mother liquor, after absorbing the waste heat from the primary condensate, will have its temperature further increased, reaching the preset temperature standard for the process. It will then be discharged from the heat exchanger through drain pipe 16 and directly enter the subsequent MVR concentration system for the concentration and purification of lithium hydroxide. Once the waste heat recovery is complete, if it is necessary to switch back to the pre-cooling condition of the causticizing liquid, simply shutting down the corresponding medium's transfer pump and switching the pipeline valves allows for a rapid switchover. The entire switching process is convenient and efficient, without affecting the overall production rhythm, and is fully compatible with continuous production process requirements.

[0078] When the entire production process is completed, or when the equipment requires maintenance after a certain operating cycle, the standardized shutdown and maintenance procedures must be followed to ensure the equipment's performance and service life. First, all heat exchange medium transfer pumps must be shut down, and all valves on the inlet pipe 15 and outlet pipe 16 must be closed to cut off the medium's flow path. Then, the pre-installed drain valve at the bottom of the heat exchanger should be opened to completely empty the remaining heat exchange medium from both chambers and the heat exchange pipe 14, preventing crystallization or corrosion of the residual medium inside the equipment.

[0079] After the medium is emptied, a comprehensive cleaning and maintenance operation is required for the equipment. A dedicated cleaning solution is introduced into the equipment through the inlet pipe 15, allowing it to flow freely within the heat exchange pipes 14 and the cavity, thoroughly removing any crystal particles, dirt, and impurities adhering to the inner walls of the pipes. After cleaning, the inside of the equipment is repeatedly rinsed with clean water until the water is clear and free of impurities. Then, nitrogen gas is introduced again for purging to completely dry any remaining moisture inside the equipment, preventing pipe corrosion caused by residual moisture.

[0080] After cleaning, a comprehensive inspection and maintenance of the equipment is required, with a focus on a detailed inspection of each seal 17. If aging, wear, or deformation of the sealing strips 176 and elastic pressure strips 173 are found, affecting sealing performance, they should be replaced promptly. Simultaneously, check the core heat exchange components such as heat exchange pipes 14 and plates 11 for corrosion, damage, or deformation; repair or replace any defects found. Also check the connections of structural components such as the support base 2 and frame 12, ensuring that all connections are secure and free from looseness or deformation. After all maintenance work is completed, close all valves and drain ports of the equipment, seal the inlets and outlets to prevent dust and impurities from entering the equipment, and then place the equipment in a dry and ventilated environment, awaiting the next startup and use.

[0081] This filtration mother liquor-causticizing liquid heat exchanger, through targeted structural optimization and design, can bring many significant benefits when put into use in the preparation process of battery-grade lithium hydroxide. It can comprehensively optimize and improve the entire process from multiple dimensions such as energy consumption, production efficiency, and product quality. The specific benefits are reflected in many aspects.

[0082] Firstly, this heat exchanger, through the synergistic design of multiple enhanced heat exchange structures, effectively improves the heat exchange efficiency between the causticizing liquid and the low-temperature filtered mother liquor. This allows for the full and efficient recovery and utilization of the cold energy carried by the low-temperature filtered mother liquor, significantly reducing the energy consumption of high-energy-consuming chilled water in subsequent cryogenic processes. In traditional heat exchange processes, the heat exchangers used generally suffer from low heat exchange efficiency and insufficient cold energy recovery, requiring a large amount of chilled water to meet the cooling requirements of the causticizing liquid, resulting in high energy consumption. This heat exchanger, through the synergistic effect of multiple structures such as the guide plate 112, the herringbone corrugated plate 113, and the turbulence column 141, significantly improves the cold energy recovery efficiency and greatly reduces the consumption of chilled water. This reduces the energy consumption of the entire preparation process from the core, effectively reducing the company's production and manufacturing costs.

[0083] Secondly, in the waste heat recovery operation of primary condensate, this heat exchanger can efficiently recover the waste heat carried by the high-temperature primary condensate and fully transfer this heat to the filtered mother liquor, effectively raising its temperature. This cascade utilization of waste heat fundamentally avoids the heat waste caused by direct cooling of the high-temperature primary condensate. Simultaneously, it eliminates the need for additional steam heating before the heated filtered mother liquor enters the MVR concentration system, further reducing steam energy consumption. In traditional lithium hydroxide preparation processes, the waste heat carried by the primary condensate is often directly dissipated into the air, resulting in significant energy waste. The application of this heat exchanger successfully achieves energy recycling, significantly improving the overall energy utilization rate of the process. This aligns with current green and low-carbon production concepts and saves enterprises substantial energy costs.

[0084] Furthermore, the dual-sealing structure design of this heat exchanger fundamentally solves the common problem of media leakage in traditional heat exchangers, ensuring comprehensive protection against cross-contamination between different heat exchange media. In the preparation process of battery-grade lithium hydroxide, the purity of the product has extremely high industry standards and process requirements. Any form of media cross-contamination can lead to excessive impurities in the final product, thus affecting its quality and grade. This heat exchanger, with its stable and reliable sealing performance, can fully guarantee the purity of various heat exchange media such as causticizing liquid, filtrate mother liquor, and primary condensate. It provides a solid guarantee for the subsequent preparation of high-purity battery-grade lithium hydroxide products from the heat exchange stage, effectively reducing rework and waste caused by substandard product quality, and improving product yield and production efficiency.

[0085] Meanwhile, the overall structural design of this heat exchanger is fully adapted to the needs of modern continuous production processes. It allows for rapid switching between two core operating conditions through simple valve changes, without requiring machine downtime or replacement of any equipment parts, significantly increasing the effective operating time of the equipment. In traditional production processes, due to the poor adaptability of the heat exchangers used, multiple different heat exchange devices are often required, or intermittent operation is employed, resulting in high equipment investment costs and low overall production efficiency. The implementation of this heat exchanger allows the core processes of cold energy recovery and waste heat utilization to proceed continuously and uninterruptedly, perfectly matching the continuous operation rhythm of the entire lithium hydroxide preparation process. This effectively improves the overall production line efficiency and better meets the actual needs of large-scale industrial production.

[0086] In addition, the modular design of this heat exchanger makes installation, disassembly, and daily maintenance more convenient. Meanwhile, its various enhanced heat exchange structures effectively reduce the adhesion and accumulation of crystal particles in the medium on the inner wall of the pipes, significantly extending the equipment's cleaning cycle and reducing the workload and frequency of daily maintenance. The high reliability of the double-sealing structure also effectively reduces the frequency of replacing seal 17, further lowering the equipment's maintenance costs. Overall, the reduced energy consumption, increased production efficiency, guaranteed product quality, and reduced maintenance costs combine to enhance the overall economic benefits of the lithium hydroxide preparation process, creating higher profit margins and market competitiveness for production enterprises.

[0087] In addition to the aforementioned core benefits, this heat exchanger, through targeted structural optimization design, has also successfully solved many other problems that traditional heat exchangers face in practical applications. Solving these problems further improves the performance of the equipment and makes the entire manufacturing process more stable and smooth.

[0088] Traditional heat exchangers, lacking effective medium guidance and turbulence-inducing structural design, often suffer from uneven medium flow and insufficient local heat exchange during actual operation. This directly leads to unstable heat exchange performance, affecting the accuracy of parameter control throughout the process. This heat exchanger, however, utilizes the uniform flow distribution effect of the conical guide plate 112 to ensure the heat exchange medium is evenly distributed to each heat exchange pipe 14, fundamentally preventing localized medium accumulation. Simultaneously, the synergistic turbulence effect of the herringbone corrugations 113 and the arc-shaped turbulence-inducing columns 141 promotes a stable turbulent flow state, ensuring more thorough contact between the medium and the heat exchange surface. This effectively solves the problem of uneven heat exchange, guarantees the stability of the heat exchange effect, and allows for precise control of various temperature parameters in the process, laying a solid foundation for the stable operation of subsequent processes.

[0089] In traditional heat exchanger operations, seal failure under low-temperature conditions is a common problem. Low temperatures can cause sealing materials to become brittle and shrink, leading to decreased sealing performance and media leakage. However, the seals 17 used in this heat exchanger are made of low-temperature resistant elastic materials, which can adapt well to low-temperature working environments, thus preventing seal material embrittlement and failure. Simultaneously, the elastic sealing structure composed of the elastic pressure strip 173 and spring 174 can flexibly compensate for thermal shrinkage deformation caused by the equipment under low-temperature conditions, ensuring that the sealing surface always maintains a tight fit. This successfully solves the industry problem of seal failure under low-temperature conditions and guarantees stable operation of the equipment across the entire temperature range of the process.

[0090] Traditional heat exchangers, during long-term operation, suffer from structural deformation and loose component connections due to continuous vibration and frequent temperature changes. This not only affects heat exchange efficiency but also reduces the equipment's lifespan and operational safety. This new heat exchanger employs a high-strength frame 12 and integrated welded plate 11 design, significantly improving the overall structural strength. The stable support base 2 effectively distributes the operating load and reduces the impact of vibration on the structure. Simultaneously, the herringbone corrugations 113 on the plates 11 not only improve heat exchange efficiency but also enhance the structural rigidity of the plates 11. These multiple structural designs collectively address the insufficient structural strength of traditional heat exchangers, effectively extending the equipment's lifespan and significantly improving its operational safety and stability.

[0091] Traditional heat exchangers are often only suitable for a single heat exchange condition. When a process requires multiple heat exchange functions, multiple different heat exchange devices must be equipped. This not only leads to high equipment investment costs but also occupies a large amount of production space and complicates the process flow. This heat exchanger, through the cavity separation design of the isolation plate 13, forms two independent heat exchange chambers, which can simultaneously adapt to both cold energy recovery and waste heat utilization. The switching of operating conditions can be completed simply by changing valves, successfully solving the problem of poor multi-condition adaptability of traditional heat exchangers. This significantly simplifies the process flow, reduces equipment investment costs and floor space, and makes the layout of the entire production line more compact and reasonable.

[0092] Traditional heat exchangers commonly suffer from high flow resistance, primarily due to inefficient piping layout and a lack of effective flow guidance structures. This results in significant impact and flow resistance during medium flow, requiring more power to transport the medium and increasing operating costs. The conical guide plate 112 in this heat exchanger effectively guides the medium entering the chamber, reducing impact resistance. Simultaneously, the arc-shaped turbulence column 141 enhances the turbulence effect without excessively obstructing flow, further reducing overall flow resistance. This optimized design not only reduces power consumption for medium transport and lowers operating costs but also prevents instability caused by excessive flow resistance, ensuring stable operation of the entire process.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A processing method for preparing battery-grade lithium hydroxide, characterized in that, include: S1. Preparation of lithium sulfate solution: After crushing lithium ore to a reasonable particle size, it is fed into a roasting furnace. The high-temperature roasting process destroys the crystal structure of the lithium ore. The roasted ore clinker is then fed into a reaction vessel, where sulfuric acid solution is added for acidification. Water is then added to the acidification reaction system for leaching to obtain a crude leaching solution containing lithium sulfate. Suspended particles and soluble impurities in the crude leaching solution are removed through sedimentation, filtration, and impurity removal processes to finally obtain a pure lithium sulfate solution. S2. Preparation of lithium hydroxide monohydrate: A pure lithium sulfate solution is fed into a causticizing reactor, and a 50% sodium hydroxide solution is added to carry out the causticizing reaction to generate lithium hydroxide monohydrate and sodium sulfate. After the reaction is completed, the solution is filtered to obtain a causticizing solution containing sodium sulfate and lithium hydroxide monohydrate. S3. Multi-stage cooling: The causticizing liquid is sent into a multi-stage cooling system for step cooling to form a slurry containing a large amount of sodium sulfate crystals; S4. Solid-liquid separation: The slurry is fed into a centrifugal separator. The resulting solid sodium sulfate crystals are transported to the sodium sulfate workshop for resource recovery. The resulting low-temperature filtered mother liquor is returned to S3 as a cold source to pre-cool the newly fed causticizing liquid, thus completing the closed loop of cold energy recovery. S5. Waste heat recovery: After the low-temperature filtered mother liquor completes the heat exchange in S3, it immediately enters the primary filtered mother liquor-secondary condensate heat exchanger to participate in the waste heat recovery of the condensate. S6. Preparation of battery-grade lithium hydroxide: The filtered mother liquor after temperature rise is directly sent to the MVR concentration system. The concentrated liquid is filtered, washed and dried to finally obtain battery-grade lithium hydroxide product.

2. The processing technology for preparing battery-grade lithium hydroxide according to claim 1, characterized in that: The multi-stage cooling system includes multiple cooling steps, namely, primary precooling, secondary precooling, tertiary primary crystallization cooling, and quaternary cryogenic crystallization.

3. The processing technology for preparing battery-grade lithium hydroxide according to claim 2, characterized in that: The first-stage precooling specifically includes: sending the causticizing liquid into a circulating water-causticizing liquid heat exchanger to exchange heat indirectly with the circulating water; The secondary precooling specifically includes: sending the causticized liquid after primary precooling into a filtration mother liquor-causticized liquid heat exchanger to indirectly exchange heat with the low-temperature filtration mother liquor from the subsequent solid-liquid separation process; The three-stage primary crystallization cooling specifically includes: sending the causticizing liquid after the second-stage precooling into a primary crystallizer for indirect heat exchange with chilled water; The fourth-stage cryogenic crystallization specifically includes: sending the causticizing liquid containing crystal nuclei after cooling from the third-stage primary crystallization into a cryogenic crystallization tank, where it continues to exchange heat indirectly with chilled water to obtain the slurry containing a large amount of sodium sulfate crystals.

4. The processing technology for preparing battery-grade lithium hydroxide according to claim 3, characterized in that: The filtered mother liquor-causticizing liquid heat exchanger includes a heat exchange body (1), and a support base (2) is provided at the bottom of the heat exchange body (1). The heat exchange body (1) includes a frame (12), with plates (11) fixedly connected to both ends of the frame (12), and an isolation plate (13) provided in the middle of the plate (11). The plate (11) has symmetrically arranged cavities with the frame (12) as the boundary, and heat exchange pipes (14) are provided on the inner side of each cavity. One end of the heat exchange pipe (14) is fixedly connected to the inlet pipe (15), and the other end of the heat exchange pipe (14) is fixedly connected to the outlet pipe (16); The heat exchange pipe (14) and the inlet pipe (15) are fitted with a sealing element (17) to ensure a seal.

5. The processing method for preparing battery-grade lithium hydroxide according to claim 4, characterized in that: The sealing element (17) includes an inner fixing ring (175) that connects the heat exchange pipe (14) and the inlet pipe (15), and the inner wall of the inner fixing ring (175) is provided with an L-shaped sealing strip (176).

6. The processing method for preparing battery-grade lithium hydroxide according to claim 5, characterized in that: The sealing element (17) also includes a sealing tube (171) located outside the inner fixing ring (175). The inner wall of the sealing tube (171) is provided with a channel (172), and the inner wall of the channel (172) is provided with an elastic pressure strip (173) along the circumferential direction.

7. The processing method for preparing battery-grade lithium hydroxide according to claim 6, characterized in that: A fixed rod is slidably connected in the middle of the elastic pressure strip (173). The fixed rod is embedded in the inner wall of the channel (172). A spring (174) is sleeved on the outer wall of the fixed rod. The outer wall of the spring (174) is elastically connected to the inner wall of the elastic pressure strip (173).

8. The processing method for preparing battery-grade lithium hydroxide according to claim 4, characterized in that: The heat exchange pipe (14) has a turbulence column (141) on the inner wall of one end near the inlet pipe (15). The turbulence column (141) is arc-shaped and is evenly arranged on the inner wall of the heat exchange pipe (14) in a circumferential direction.

9. The processing method for preparing battery-grade lithium hydroxide according to claim 4, characterized in that: The plate (11) is fixedly connected to a guide plate (112) on the side near the frame (12), and the outer wall of the guide plate (112) is tapered. The plate (11) is provided with corrugations (113) on the other side near the frame (12), and the corrugations (113) are herringbone-shaped.

10. A processing method for preparing battery-grade lithium hydroxide according to any one of claims 1-9, characterized in that: The primary condensate from the secondary steam condensation of the MVR concentration process first enters a circulating water-primary condensate heat exchanger, where it exchanges heat indirectly with the circulating water. The cooled primary condensate then enters the filtered mother liquor-secondary condensate heat exchanger for indirect heat exchange with the filtered mother liquor.

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