A method and equipment for treating lithium-containing wastewater

Abstract

This invention discloses a method and equipment for treating lithium-containing wastewater. The method includes the following steps: S1, pretreatment of high-chlorine lithium-containing wastewater; S2, reverse osmosis membrane separation; S3, MVR evaporation and concentration; S4, sodium precipitation and lithium separation; S5, carbonate precipitation of lithium. Before evaporation and concentration, the primary concentrate can exchange heat with a lithium-rich solution to preheat the primary concentrate and cool the lithium-rich solution. This invention establishes a heat exchange system between the primary concentrate and the lithium-rich mother liquor, utilizing the excess heat of the lithium-rich mother liquor to raise the temperature of the primary concentrate entering the MVR evaporator, shortening the MVR evaporation and concentration time, and also enabling rapid cooling of the lithium-rich mother liquor, shortening the lithium precipitation process time. This significantly reduces the overall time of the lithium-containing wastewater treatment process, improves treatment efficiency, and achieves heat recovery and rational utilization, making the lithium-containing wastewater treatment process more economical and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method and equipment for treating lithium-containing wastewater. Background Technology

[0002] Lithium metal, known as the "metallic flavor enhancer," can significantly alter the properties of alloys with just a small amount, thus finding widespread application in aerospace, nuclear power generation, high-energy batteries, and lightweight, high-strength alloys, earning it the title of "the metal of the 21st century." High-chlorine lithium-containing wastewater has a relatively high lithium concentration, thus possessing good recycling value. The economic benefits of lithium recovery from lithium industry wastewater, based on the market's annual lithium production and the lithium content in the wastewater, translate to at least 1 billion yuan in recovery value when converted to lithium carbonate prices.

[0003] The key to treating high-chlorine lithium-containing wastewater lies in the removal of impurity ions and the separation of lithium and sodium salts. According to the treatment requirements, existing technologies employ a process route of high-efficiency removal of organic pollutants—nanofiltration membrane removal of calcium and magnesium—special membrane separation and pre-concentration—MVR evaporation and concentration—sodium precipitation and lithium separation—sodium carbonate precipitation of lithium. This fractional treatment method removes impurities from the wastewater, allowing for the enrichment and concentration of effective components.

[0004] The concentrated mother liquor obtained from MVR evaporation is a mixed solution rich in lithium chloride and sodium chloride, with a high concentration and viscosity. It is then processed by a sodium-lithium precipitation device, utilizing the significant difference in solubility between lithium chloride and sodium chloride to first crystallize out sodium chloride. After centrifugation, sodium chloride crystals are obtained, which are considered general solid waste. The resulting lithium-rich solution is then fed into a sodium carbonate precipitation device, where lithium chloride is converted into lithium carbonate precipitate at a specific temperature. This precipitate is then separated by centrifugation to obtain the final lithium carbonate precipitate.

[0005] Since the reaction temperature of the sodium carbonate lithium precipitation process is 30-60 degrees Celsius, which is much lower than the temperature of the lithium-rich solution and sodium chloride solid waste obtained after sodium precipitation and lithium separation, the lithium-rich solution needs to be naturally cooled for a certain period of time before sodium carbonate reagent can be added for reaction, and the sodium chloride solid waste needs to be cooled before further treatment. This not only greatly increases the process time, resulting in low treatment efficiency of high-chlorine lithium-containing wastewater, but also causes a lot of energy waste and reduces the economic and environmental performance of the process.

[0006] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a method and equipment for treating lithium-containing wastewater.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a method and equipment for treating lithium-containing wastewater, which can solve the problems of low process efficiency and energy waste caused by cooling lithium-rich solutions and sodium chloride solid waste, and effectively improve the treatment efficiency and economic and environmental performance of high-chlorine lithium-containing wastewater.

[0009] To achieve the above objectives, a specific embodiment of the present invention provides a method for treating lithium-containing wastewater, comprising the following steps:

[0010] S1. Pretreatment of high-chlorine lithium-containing wastewater: Adjust the pH of the high-chlorine lithium-containing wastewater to weakly acidic, and then filter to remove impurities and suspended solids from the water;

[0011] S2. Reverse osmosis membrane separation: The membrane osmosis device using membrane separation technology separates dissolved salts from wastewater to obtain primary concentrate and reclaimed water.

[0012] S3, MVR evaporation and concentration: The primary concentrate is further evaporated and concentrated in an MVR evaporator to obtain a secondary concentrate;

[0013] S4. Sodium precipitation and lithium separation: The secondary concentrate is transferred to the thickening system for further concentration, and then centrifuged and filtered to obtain sodium chloride solid crystalline salt and lithium-rich solution.

[0014] S5, Lithium carbonate precipitation: After the lithium-rich solution is cooled in the lithium precipitation reactor, a carbonate solution is added to react and generate lithium carbonate precipitate. The precipitate is then separated by centrifugation to obtain the finished lithium carbonate product.

[0015] Before entering the MVR evaporator for evaporation and concentration, the primary concentrate can exchange heat with the lithium-rich solution through a spiral heat exchange tube in the lithium precipitation reactor, thereby preheating the primary concentrate and cooling the lithium-rich solution.

[0016] To achieve the above objectives, a specific embodiment of the present invention provides a lithium-containing wastewater treatment device, including a membrane permeation device, a lithium precipitation reactor, and an MVR evaporator;

[0017] The membrane permeation device includes a primary membrane separation module and a secondary membrane separation module, which can sequentially permeate and separate dissolved salts in wastewater to obtain a primary concentrate.

[0018] The MVR evaporator is located at the rear end of the membrane permeation unit. A feed pipeline is fixedly installed between the membrane permeation unit and the MVR evaporator. The primary concentrate is fed into the MVR evaporator through the feed pipeline for evaporation and concentration to obtain the secondary concentrate.

[0019] A heating sodium precipitation device is fixedly installed above the MVR evaporator. The heating sodium precipitation device is used to further heat and crystallize the secondary concentrate to precipitate sodium chloride solid.

[0020] The lithium precipitation reactor is internally connected to a stirring tube, and a porous drum is fixedly installed above the stirring tube. The porous drum is used to centrifuge and separate the lithium-rich solution. A liquid collecting cylinder is fixedly installed on the outside of the porous drum. Multiple sets of liquid outlet holes are opened on the outer wall of the liquid collecting cylinder. A flow guiding ring is fixedly installed below the liquid collecting cylinder. A slow-release chamber is formed between the inner wall of the lithium precipitation reactor and the outer wall of the flow guiding ring. The lithium-rich solution can flow into the slow-release chamber through the multiple sets of liquid outlet holes. Multiple sets of liquid outlet pipes are fixedly installed at the bottom end of the flow guiding ring.

[0021] The feeding pipeline includes a spiral heat exchange tube, which is coiled around the outside of the flow guide ring and located inside the slow release chamber. The lithium-rich solution entering the slow release chamber can directly contact the spiral heat exchange tube, thereby exchanging heat with the primary concentrate inside the spiral heat exchange tube.

[0022] In one or more embodiments of the present invention, a base is fixedly installed below the lithium precipitation reactor, and the base has a hollow structure for storing sodium chloride solid.

[0023] The top end of the stirring tube is connected to the inside of the porous drum, and the bottom end of the stirring tube is connected to the inside of the hollow structure inside the base. The sodium chloride solid separated inside the porous drum can fall into the inside of the hollow structure through the stirring tube.

[0024] A second solenoid valve is fixedly installed on the stirring tube near the top.

[0025] In one or more embodiments of the present invention, a first solenoid valve is fixedly installed on the stirring tube near the bottom end. The first solenoid valve allows the sodium chloride solid entering the stirring tube to remain inside the stirring tube, and the heat of the sodium chloride solid is used to maintain the temperature of the lithium precipitation reaction.

[0026] In one or more embodiments of the present invention, a stirring motor is fixedly installed on the base, and a belt is installed between the output end of the stirring motor and the stirring tube, so that the stirring motor can drive the stirring tube to rotate via the belt;

[0027] Multiple sets of blades are fixedly installed on the stirring tube, which enables the stirring tube to stir during the lithium precipitation reaction.

[0028] In one or more embodiments of the present invention, a water distribution box is fixedly installed on the liquid collection cylinder, and a plurality of spray nozzles are fixedly installed on the water distribution box;

[0029] A steam main pipe is fixedly installed on the MVR evaporator, and a steam branch pipe is connected to the steam main pipe. One end of the steam branch pipe is connected to the inside of the water distribution box.

[0030] Control valves are installed on both the main steam pipe and the branch steam pipe.

[0031] In one or more embodiments of the present invention, a helical toothed ring is rotatably connected to the outer wall of the liquid collecting cylinder, and a rotating sleeve is fixedly installed on the helical toothed ring;

[0032] A control motor is fixedly installed on the lithium deposition reactor. The output end of the control motor extends into the interior of the lithium deposition reactor and is fixedly installed with a helical gear. The helical gear is matched with a helical gear ring.

[0033] The liquid outlet includes multiple sets of internal liquid outlets formed on the liquid collecting cylinder and multiple sets of external liquid outlets formed on the rotating sleeve;

[0034] The rotating sleeve is sealed and fitted to the outer wall of the liquid collecting cylinder, and the multiple sets of inner liquid outlet holes are respectively matched with the multiple sets of outer liquid outlet holes.

[0035] In one or more embodiments of the present invention, a dosing system is fixedly installed on the lithium precipitation reactor. The dosing system is connected to multiple sets of liquid outlet pipes and can add carbonate solution to the lithium-rich solution through the multiple sets of liquid outlet pipes.

[0036] The multiple sets of liquid outlet pipes have cavities inside, and multiple sets of bosses are fixedly installed on the inner wall of the liquid outlet pipes. The bosses have medicine outlet holes, and the cavity is connected to the inside of the liquid outlet pipe through the medicine outlet holes.

[0037] In one or more embodiments of the present invention, the dosing system includes a dosing cylinder and a ring pipe, the dosing cylinder is fixedly mounted on a base, and a dosing pump is fixedly mounted on the dosing cylinder;

[0038] The ring pipe is fixedly installed outside the lithium precipitation reactor, and a delivery pipe is fixedly installed between the output end of the dosing pump and the ring pipe;

[0039] Multiple sets of injection tubes are fixedly installed on the ring tube, and the multiple sets of injection tubes are respectively connected to multiple sets of liquid outlet tubes.

[0040] In one or more embodiments of the present invention, the feeding pipeline further includes a concentrate pipe and a concentrate branch pipe, wherein the concentrate pipe is fixedly installed between the primary membrane separation module and the MVR evaporator, and the concentrate branch pipe is fixedly installed between the secondary membrane separation module and the concentrate pipe;

[0041] The spiral heat exchange tube is fixedly installed on the concentrate tube;

[0042] A water pipe is fixedly installed between the primary membrane separation module and the secondary membrane separation module.

[0043] Compared with the prior art, the present invention establishes a heat exchange system between the primary concentrate and the lithium-rich mother liquor. This system utilizes the excess heat of the lithium-rich mother liquor to raise the temperature of the primary concentrate entering the MVR evaporator, thus shortening the MVR evaporation and concentration time. It also enables the lithium-rich mother liquor to cool down rapidly, shortening the lithium precipitation process time. As a result, the overall time of the lithium-containing wastewater treatment process is significantly shortened, the treatment efficiency is improved, and heat recovery and rational utilization are achieved.

[0044] The stirring tube not only facilitates the discharge and collection of sodium chloride solid waste, but also allows the heat from the sodium chloride solid waste to maintain the temperature required for the lithium precipitation reaction, further realizing heat recovery and utilization, making the lithium-containing wastewater treatment process more economical and environmentally friendly.

[0045] Multiple sets of outlet pipes can be used to uniformly add carbonate solution to lithium-rich mother liquor, saving the time of chemical mixing in the lithium precipitation process and improving the lithium precipitation efficiency. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 The structure of a lithium-containing wastewater treatment device in one embodiment of the present invention is shown below. Figure 1 ;

[0048] Figure 2 The structure of a lithium-containing wastewater treatment device in one embodiment of the present invention is shown below. Figure 2 ;

[0049] Figure 3 This is a front view of a lithium-containing wastewater treatment device according to an embodiment of the present invention;

[0050] Figure 4 This is a cross-sectional view of a lithium precipitation reactor in a lithium-containing wastewater treatment device according to an embodiment of the present invention.

[0051] Figure 5 This is a partially enlarged view of the flow-guiding baffle ring of a lithium-containing wastewater treatment device according to an embodiment of the present invention;

[0052] Figure 6 This is a structural diagram of the liquid collection cylinder of a lithium-containing wastewater treatment device according to an embodiment of the present invention;

[0053] Figure 7 This invention provides a lithium-containing wastewater treatment device according to one embodiment. Figure 4 Enlarged view of point A in the middle;

[0054] Figure 8 This invention provides a lithium-containing wastewater treatment device according to one embodiment. Figure 5 Enlarged view at point B in the middle;

[0055] Figure 9 This is a bottom cross-sectional view of the outlet pipe of a lithium-containing wastewater treatment device according to an embodiment of the present invention;

[0056] Figure 10 This is a structural diagram of the stirring tube of a lithium-containing wastewater treatment device according to an embodiment of the present invention;

[0057] Figure 11 This is a schematic diagram of the cleaning of a porous drum in a lithium-containing wastewater treatment device according to an embodiment of the present invention;

[0058] Figure 12 This is a flowchart of a lithium-containing wastewater treatment method according to an embodiment of the present invention.

[0059] Explanation of key figure labels:

[0060] 10. Membrane permeation unit; 11. Primary membrane separation module; 12. Secondary membrane separation module; 13. Water guide pipe; 14. Concentrate pipe; 15. Concentrate branch pipe; 16. Spiral heat exchanger tube; 20. Lithium precipitation reactor; 21. Top cover; 22. Porous drum; 23. Collection cylinder; 231. Water distribution box; 2311. Nozzle; 232. Slanted toothed ring; 2321. Rotating sleeve; 2322. Outlet liquid port; 233. Inner outlet liquid port; 24. Drainage baffle ring; 241. Conical part; 242. Outlet pipe; 2421 1. Cavity; 2422. Boss; 2423. Discharge port; 30. MVR evaporator; 31. Steam main pipe; 32. Steam branch pipe; 40. Base; 41. Discharge baffle; 50. Storage cylinder; 51. Dosing pump; 511. Delivery pipe; 52. Ring pipe; 521. Injection pipe; 60. Heating sodium precipitation device; 61. Feed pipe; 70. Stirring pipe; 71. First solenoid valve; 72. Second solenoid valve; 73. Blade; 80. Stirring motor; 81. Belt; 90. Control motor; 91. Helical gear. Detailed Implementation

[0061] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0062] like Figure 12As shown, a lithium-containing wastewater treatment method according to an embodiment of the present invention includes the following steps:

[0063] S1. Pretreatment of high-chlorine lithium-containing wastewater: Adjust the pH of the high-chlorine lithium-containing wastewater to weakly acidic, and then filter to remove impurities and suspended solids from the water;

[0064] Specifically, the pretreatment steps for high-chlorine lithium-containing wastewater are, in sequence, neutralization pretreatment, filtration, and ultrafiltration.

[0065] Since the raw water for the high-chlorine lithium-containing wastewater comes from the washing water of the upstream resin adsorption, the water quality is characterized by large fluctuations in acidity and alkalinity, as well as large fluctuations in salt composition and content. Considering that the subsequent concentration mainly adopts membrane separation technology, a neutralization pretreatment system needs to be designed to adjust the pH of the raw water and keep it stable. Due to the variable acidity and alkalinity of the water, the acid and alkali addition systems are all taken into account. The acid used is dilute hydrochloric acid, and the alkali is liquid alkali. The device is equipped with an online pH monitoring and control loop.

[0066] The filtration system employs a precision filtration device to reduce suspended solids in the raw water and minimize the impact of impurities such as particles and colloidal droplets on subsequent systems.

[0067] Ultrafiltration, as a pretreatment for reverse osmosis membrane separation, removes some large molecular impurities and tiny suspended solids, further reducing turbidity, maintaining stable operation of downstream membrane devices, and extending membrane lifespan.

[0068] S2. Dissolved salts in wastewater are separated by membrane osmosis in membrane osmosis unit 10 using membrane separation technology to obtain primary concentrate and reclaimed water;

[0069] Specifically, membrane separation technology is used to concentrate salt in raw water. The membrane material's high removal rate of dissolved salts yields high-quality permeate, which can then be reused or meet discharge standards. The membrane permeation unit 10 uses organic spiral wound membrane materials and elements to achieve the permeation separation of water and salt under a certain pressure.

[0070] More specifically, the primary membrane separation module 11 separates the permeate containing a small amount of salt, which then enters the secondary membrane separation module 12 through the water inlet pipe 13 for further desalination, ensuring the desalination rate. Dissolved salts are enriched in the concentrate to form the primary concentrate.

[0071] S3, MVR Evaporation and Concentration: The primary concentrate is further evaporated and concentrated in the MVR evaporator 30 to obtain the secondary concentrate;

[0072] Specifically, the primary concentrate obtained from reverse osmosis already has a high salt content. It is further concentrated by evaporation. The evaporation system uses MVR technology, which operates continuously and stably with low energy consumption. After concentration, a secondary concentrate is obtained. The secondary concentrate is a saturated salt solution, and correspondingly, the concentration of the valuable component lithium in the secondary concentrate is also increased.

[0073] S4. Sodium precipitation and lithium separation: The secondary concentrate is transferred to the thickening system for further concentration, and then centrifuged and filtered to obtain sodium chloride solid crystalline salt and lithium-rich solution.

[0074] Specifically, once the sodium chloride concentration in the MVR system reaches the discharge concentration, the liquid is transferred to a thickening system for further concentration. After filtration and centrifugation, sodium chloride solid crystalline salt and lithium-rich solution are obtained.

[0075] S5, Lithium carbonate precipitation: After the lithium-rich solution is cooled in the lithium precipitation reactor 20, a carbonate solution is added to react and generate lithium carbonate precipitate. The precipitate is then separated by centrifugation to obtain the finished lithium carbonate product.

[0076] Before entering the MVR evaporator 30 for evaporation and concentration, the primary concentrate can exchange heat with the lithium-rich solution in the lithium precipitation reactor 20 through the spiral heat exchange tube 16, preheating the primary concentrate and cooling the lithium-rich solution. See below for details:

[0077] like Figures 1-11 As shown, a lithium-containing wastewater treatment device includes a membrane permeation device 10, a lithium precipitation reactor 20, an MVR evaporator 30, a base 40, a chemical storage cylinder 50, a heating sodium precipitation device 60, a stirring tube 70, and a stirring motor 80.

[0078] like Figures 1-3 As shown, the membrane permeation device 10 includes a primary membrane separation module 11 and a secondary membrane separation module 12. The primary membrane separation module 11 and the secondary membrane separation module 12 can sequentially permeate and separate dissolved salts in wastewater to obtain a primary concentrate.

[0079] Feeding pipelines are fixedly installed on the primary membrane separation module 11 and the secondary membrane separation module 12. The feeding pipelines include a concentrate pipe 14 and a concentrate branch pipe 15. The concentrate pipe 14 is fixedly installed between the primary membrane separation module 11 and the MVR evaporator 30, and the concentrate branch pipe 15 is fixedly installed between the secondary membrane separation module 12 and the concentrate pipe 14.

[0080] Specifically, the primary concentrate produced by the primary membrane separation module 11 can be transported to the MVR evaporator 30 through the concentrate pipe 14. A water guide pipe 13 is fixedly installed between the primary membrane separation module 11 and the secondary membrane separation module 12. The permeate from the primary membrane separation module 11 contains a small amount of salt, which can enter the secondary membrane separation module 12 through the water guide pipe 13 for further desalination, ensuring the desalination rate. The primary concentrate produced by the secondary membrane separation module 12 can first enter the concentrate pipe 14 through the concentrate branch pipe 15, and then enter the MVR evaporator 30 through the concentrate pipe 14.

[0081] The primary concentrate enters the MVR evaporator 30 for evaporation and concentration to obtain the secondary concentrate.

[0082] Specifically, the MVR evaporator 30 is located at the rear end of the membrane permeation unit 10. Inside the MVR evaporator 30, the primary concentrate is evaporated and concentrated by steam heating to obtain the secondary concentrate. A heating sodium precipitation device 60 is fixedly installed above the MVR evaporator 30. The secondary concentrate is pumped into the heating sodium precipitation device 60, where it is further heated for thickening and concentration. Taking advantage of the significant difference in solubility between lithium chloride and sodium chloride, sodium chloride is crystallized and precipitated first, thereby causing solid sodium chloride to crystallize and precipitate from the secondary concentrate inside the heating sodium precipitation device 60.

[0083] like Figure 4 As shown, a stirring tube 70 is rotatably connected inside the lithium deposition reactor 20, and a porous drum 22 is rotatably connected to the top of the reactor 20. The top of the stirring tube 70 is fixedly connected to the bottom of the porous drum 22, and the stirring tube 70 is located on the central axis of the porous drum 22. The stirring tube 70 can drive the porous drum 22 to rotate.

[0084] The top of the lithium precipitation reactor 20 is fixedly installed with a top cover 21, and the top of the heating sodium precipitation device 60 is fixedly installed with a feed pipe 61. The outlet end of the feed pipe 61 is fixed to the top of the top cover 21 and is connected to the inside of the porous drum 22.

[0085] After the secondary concentrate completes sodium precipitation and lithium separation inside the heating sodium precipitation device 60, it is then fed into the porous drum 22 through the feed pipe 61. Centrifugal separation is carried out inside the porous drum 22. The lithium-rich solution produced by centrifugal separation is centrifuged out, while the sodium chloride solid is left behind.

[0086] like Figure 6 As shown, a liquid collecting cylinder 23 is fixedly installed on the outer side of the porous drum 22, and the lithium-rich solution thrown out by the porous drum 22 is collected inside the liquid collecting cylinder 23. A helical gear ring 232 is rotatably connected to the outer wall of the liquid collecting cylinder 23, and a rotating sleeve 2321 is fixedly installed on the helical gear ring 232. The rotating sleeve 2321 can rotate with the helical gear ring 232.

[0087] Among them, such as Figure 7 As shown, the outer wall of the liquid collecting cylinder 23 has multiple sets of inner liquid outlet holes 233, and the outer wall of the rotating sleeve 2321 has multiple sets of outer liquid outlet holes 2322, with each inner liquid outlet hole 233 corresponding to one outer liquid outlet hole 2322. When the outer liquid outlet hole 2322 coincides with the inner liquid outlet hole 233, the lithium-rich solution inside the liquid collecting cylinder 23 can flow out through the multiple sets of inner liquid outlet holes 233 and outer liquid outlet holes 2322.

[0088] The rotating sleeve 2321 is sealed and fitted to the outer wall of the liquid collecting cylinder 23. When the rotating sleeve 2321 rotates, the inner liquid outlet 233 and the outer liquid outlet 2322 are completely misaligned. At this time, the rotating sleeve 2321 can seal and block the inner liquid outlet 233, and the lithium-rich solution inside the liquid collecting cylinder 23 cannot flow out.

[0089] A control motor 90 is fixedly installed on the outer wall of the lithium deposition reactor 20. The output end of the control motor 90 extends into the interior of the lithium deposition reactor 20 and is fixedly installed with a helical gear 91. The helical gear 91 meshes with a helical gear ring 232. The control motor 90 can drive the helical gear ring 232 to rotate at a certain angle through the helical gear 91.

[0090] Specifically, the control motor 90 drives the helical gear ring 232 to rotate via the helical gear 91, causing the rotating sleeve 2321 to rotate. When the outflow hole 2322 on the rotating sleeve 2321 rotates to coincide with the inner outflow hole 233, the lithium-rich solution inside the collecting cylinder 23 can flow out. When the outflow hole 2322 and the inner outflow hole 233 are misaligned, the lithium-rich solution inside the collecting cylinder 23 cannot flow out. This allows for free control of the time and amount of lithium-rich solution entering the lithium precipitation reactor 20, facilitating the orderly control of the lithium precipitation reaction inside the lithium precipitation reactor 20.

[0091] like Figure 4 and Figure 5 As shown, a flow-guiding baffle ring 24 is fixedly installed below the liquid collection cylinder 23. The flow-guiding baffle ring 24 is welded and fixed to the inner wall of the lithium deposition reactor 20, and a slow-release cavity is formed between the inner wall of the lithium deposition reactor 20 and the outer wall of the flow-guiding baffle ring 24. The lithium-rich solution flowing out from the inside of the liquid collection cylinder 23 can flow into the slow-release cavity along the inner wall of the lithium deposition reactor 20.

[0092] The guide ring 24 has a conical section 241 above it. After the lithium-rich solution flows out, it first contacts the inner wall of the lithium deposition reactor 20. If there is a large amount of lithium-rich solution inside the collecting cylinder 23, the liquid flow rate will be high, causing splashing upon contact with the inner wall of the lithium deposition reactor 20. The conical section 241 can block and guide the splashed liquid, ensuring that the lithium-rich solution can smoothly enter the slow-release chamber.

[0093] A spiral heat exchange tube 16 is fixedly installed on the concentrate tube 14. The spiral heat exchange tube 16 is coiled around the outside of the flow guide ring 24 and located inside the slow release chamber. Both ends of the spiral heat exchange tube 16 extend to the outside of the lithium deposition reactor 20, facilitating the series connection of the spiral heat exchange tube 16 to the concentrate tube 14. In other words, the primary concentrate passes through the interior of the spiral heat exchange tube 16 during its transport within the concentrate tube 14.

[0094] There is a narrow gap between the inner side of the spiral heat exchange tube 16 and the outer wall of the flow guide ring 24, and a narrow gap between the outer side of the spiral heat exchange tube 16 and the inner wall of the lithium deposition reactor 20. Therefore, the spiral heat exchange tube 16 can play a certain role in blocking the lithium-rich solution entering the slow-release chamber, slowing down the flow rate of the lithium-rich solution after entering the slow-release chamber, and causing it to seep down along the surface of the spiral heat exchange tube 16. In other words, the lithium-rich solution entering the slow-release chamber can directly and fully contact the spiral heat exchange tube 16, thereby exchanging heat with the primary concentrate inside the spiral heat exchange tube 16.

[0095] Since the lithium-rich solution is at a relatively high temperature, it can indirectly exchange heat with the primary concentrate inside the spiral heat exchange tube 16 through direct contact with the spiral heat exchange tube 16. The primary concentrate, due to its low initial temperature, would require a long heating time to reach a certain temperature for evaporation and concentration if it directly enters the MVR evaporator 30. This results in low evaporation and concentration efficiency. However, by exchanging heat with the lithium-rich solution inside the spiral heat exchange tube 16, the primary concentrate is preheated, significantly shortening the heating time during evaporation and thus improving the evaporation and concentration efficiency.

[0096] In addition, after exchanging heat with the primary concentrate, the lithium-rich solution can rapidly decrease its own temperature, allowing it to cool to the temperature range required for lithium precipitation during its downward flow. This enables the lithium-rich solution to undergo the lithium precipitation process immediately, eliminating waiting time and improving the consistency and efficiency of the overall lithium-containing wastewater treatment process.

[0097] At the same time, by recovering and utilizing heat, heat loss can be reduced, energy can be saved, the greenhouse effect can be reduced, and the equipment can be made to work more economically and environmentally friendly.

[0098] like Figure 4 , Figure 5 and Figure 8 As shown, multiple sets of liquid outlet pipes 242 are fixedly installed at the bottom of the drainage baffle ring 24. The multiple sets of liquid outlet pipes 242 are used to export the lithium-rich solution inside the slow-release chamber.

[0099] like Figure 1 and Figure 4 As shown, a dosing system is fixedly installed on the lithium precipitation reactor 20. The dosing system includes a storage cylinder 50 and a ring pipe 52. The storage cylinder 50 is fixedly installed on the base 40, and the storage cylinder 50 stores a carbonate solution. In this embodiment, the carbonate solution is preferably a sodium carbonate solution.

[0100] A dosing pump 51 is fixedly installed on the medicine storage cylinder 50. The input end of the dosing pump 51 extends into the bottom of the medicine storage cylinder 50, and a delivery pipe 511 is fixedly installed on the output end of the dosing pump 51.

[0101] The ring pipe 52 is fixedly installed on the outside of the lithium precipitation reactor 20, and one end of the drug delivery pipe 511 is fixedly installed on the ring pipe 52. The sodium carbonate solution drawn by the dosing pump 51 can be injected into the inside of the ring pipe 52 through the drug delivery pipe 511.

[0102] Multiple sets of injection tubes 521 are fixedly installed on the ring tube 52. The multiple sets of injection tubes 521 are connected to multiple sets of outlet tubes 242 respectively. The sodium carbonate solution that enters the ring tube 52 can be injected into the outlet tubes 242 through the injection tubes 521.

[0103] Among them, such as Figure 8 and Figure 9 As shown, each of the multiple sets of outlet pipes 242 has a cavity 2421 inside. The injection pipe 521 is connected to the inside of the cavity 2421, and the sodium carbonate solution first enters the cavity 2421. Multiple sets of bosses 2422 are fixedly installed on the inner wall of the outlet pipe 242, and each boss 2422 has a dispensing hole 2423. The cavity 2421 is connected to the inside of the outlet pipe 242 through the dispensing hole 2423. The sodium carbonate solution entering the cavity 2421 can enter the outlet pipe 242 through the dispensing holes 2423 on the multiple sets of bosses 2422.

[0104] As the lithium-rich solution is discharged downwards through the outlet pipe 242, the sodium carbonate solution flows out through multiple sets of outlet holes 2423, mixing uniformly with the lithium-rich solution to complete the chemical mixing in the lithium precipitation process. The protrusion 2422 can turbulently flow through the lithium-rich solution, ensuring uniform mixing of the lithium-rich solution and sodium carbonate solution inside the outlet pipe 242.

[0105] In this way, the sodium carbonate solution addition and mixing steps are completed before the lithium-rich solution reaches the bottom of the lithium precipitation reactor 20, eliminating the time required for addition, stirring and mixing in the lithium precipitation process, greatly shortening the time required for the lithium precipitation process, further reducing the overall process time and improving efficiency.

[0106] A base 40 is fixedly installed below the lithium precipitation reactor 20. A stirring motor 80 is fixedly installed on the base 40. A belt 81 is installed between the output end of the stirring motor 80 and the stirring tube 70. The stirring motor 80 can drive the stirring tube 70 to rotate through the belt 81.

[0107] like Figure 10 As shown, multiple sets of blades 73 are fixedly installed on the stirring tube 70. The multiple sets of blades 73 are located inside the lithium precipitation reactor 20 near the bottom. The blades 73 enable the stirring tube 70 to continuously stir the solution during the lithium precipitation reaction.

[0108] Specifically, after the lithium-rich solution flows into the bottom of the lithium precipitation reactor 20 through the outlet pipe 242, the stirring motor 80 drives the stirring tube 70 to rotate through the belt 81. The blades 73 on the stirring tube 70 will continuously stir the solution to ensure the efficient progress of the reaction.

[0109] The base 40 has a hollow structure inside. The top of the stirring tube 70 is connected to the inside of the porous drum 22, and the bottom of the stirring tube 70 is connected to the inside of the hollow structure inside the base 40. The stirring tube 70 can form a passage between the porous drum 22 and the hollow structure, so that the sodium chloride solid separated inside the porous drum 22 can fall into the inside of the hollow structure through the stirring tube 70.

[0110] A discharge baffle 41 is rotatably connected to the base 40, which can remove and clean the sodium chloride solid collected inside the base 40.

[0111] A second solenoid valve 72 is fixedly installed on the stirring tube 70 near the top. The second solenoid valve 72 is used to control the closing of the top of the stirring tube 70 to ensure that the lithium-rich solution does not enter the interior of the stirring tube 70 during the centrifugation process.

[0112] like Figure 11 Combination Figure 2 As shown, a water distribution box 231 is fixedly installed on the liquid collection cylinder 23, and multiple sets of nozzles 2311 are fixedly installed on the water distribution box 231. The multiple sets of nozzles 2311 are all facing the outer wall of the porous drum 22. The multiple sets of nozzles 2311 can backflush the porous drum 22, causing the sodium chloride solid adhering to the inner wall of the porous drum 22 to fall off.

[0113] A steam main pipe 31 is fixedly installed on the MVR evaporator 30. The steam main pipe 31 is used to supply heating steam to the inside of the MVR evaporator 30. A steam branch pipe 32 is connected to the steam main pipe 31. One end of the steam branch pipe 32 is connected to the inside of the water distribution box 231. Steam can be introduced into the inside of the water distribution box 231 through the steam branch pipe 32 and finally sprayed out through the nozzle 2311.

[0114] Both the main steam pipe 31 and the branch steam pipe 32 are equipped with control valves. When it is necessary to clean the sodium chloride solid inside the porous drum 22, the control valve on the main steam pipe 31 is closed and the control valve on the branch steam pipe 32 is opened, so that steam can enter the water distribution box 231 through the branch steam pipe 32, thereby using steam to backflush and clean the porous drum 22.

[0115] Specifically, after the sodium chloride solid falls to the bottom of the porous drum 22, opening the second solenoid valve 72 allows the sodium chloride solid to enter the stirring tube 70.

[0116] It is worth noting that a first solenoid valve 71 is fixedly installed on the stirring tube 70 near the bottom. By closing the first solenoid valve 71, the sodium chloride solid that has entered the stirring tube 70 can remain inside the stirring tube 70, and the heat of the sodium chloride solid can be used to maintain the temperature of the lithium precipitation reaction.

[0117] Since the lithium precipitation reaction needs to be controlled at a temperature of 30-60℃, it is difficult to ensure the smooth progress of the reaction without a heat supply. At this point, because the sodium chloride solid itself has a high temperature, and the temperature is further increased by the steam, directly discharging it would not only make subsequent cleaning difficult, but also cause a large loss of heat energy.

[0118] Therefore, after the sodium chloride solid enters the stirring tube 70, the first solenoid valve 71 can be closed, so that the sodium chloride solid remains inside the stirring tube 70. The sodium chloride solid can indirectly heat the solution by heating the stirring tube 70 and using the blades 73 to achieve uniform heat conduction, so as to maintain the temperature of the lithium precipitation reaction.

[0119] In this way, the temperature required for the lithium precipitation reaction can be maintained without the need for external heat supply, saving energy, and the sodium chloride solid can be cooled down, which facilitates the subsequent processing of the sodium chloride solid.

[0120] In operation, lithium-containing wastewater, after neutralization pretreatment, filtration, and ultrafiltration, first enters the primary membrane separation module 11 for primary membrane separation. The resulting primary concentrate enters the concentrate pipe 14. The permeate then enters the secondary membrane separation module 12 through the water guide pipe 13 for further secondary membrane separation, yielding another portion of the primary concentrate. This concentrate then enters the concentrate pipe 14 through the concentrate branch pipe 15. The primary concentrate is then transported through the concentrate pipe 14 and preheated by heat exchange with the lithium-rich solution in the spiral heat exchange tube 16 before entering the MVR evaporator 30. After evaporation and concentration, the solution is pumped to the sodium precipitation device 60 for further heating, crystallizing out solid sodium chloride. Then, it is transported through the feed pipe 61 to the porous drum 22 for centrifugal separation to obtain a new lithium-rich mother liquor. The lithium-rich mother liquor first flows into the slow release chamber, where it exchanges heat with the spiral heat exchange tube 16 to cool down to the required temperature range. Then, it is introduced into the bottom of the lithium precipitation reactor 20 through the liquid outlet pipe 242. During the process of passing through the liquid outlet pipe 242, the sodium carbonate solution is added and mixed. The reaction is continuously stirred by the blades 73 on the stirring tube 70 to generate lithium carbonate precipitate.

[0121] This invention establishes a heat exchange system between the primary concentrate and the lithium-rich mother liquor. This system utilizes the excess heat of the lithium-rich mother liquor to raise the temperature of the primary concentrate entering the MVR evaporator 30, thus shortening the MVR evaporation and concentration time. It also enables the lithium-rich mother liquor to cool down rapidly, shortening the lithium precipitation process time. This significantly reduces the overall time of the lithium-containing wastewater treatment process, improves treatment efficiency, and achieves heat recovery and rational utilization.

[0122] The stirring tube 70 not only facilitates the discharge and collection of sodium chloride solid waste, but also allows the heat from the sodium chloride solid waste to maintain the temperature required for the lithium precipitation reaction, further realizing heat recovery and utilization, making the lithium-containing wastewater treatment process more economical and environmentally friendly.

[0123] Multiple sets of outlet pipes 242 can uniformly add carbonate solution to lithium-rich mother liquor, saving the mixing time in the lithium precipitation process and improving the lithium precipitation efficiency.

[0124] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0125] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A lithium-containing wastewater treatment device, characterized in that, include: The membrane permeation device includes a primary membrane separation module and a secondary membrane separation module, which can sequentially permeate and separate dissolved salts in wastewater to obtain a primary concentrate. The MVR evaporator is located at the rear end of the membrane permeation unit. A feed pipeline is fixedly installed between the membrane permeation unit and the MVR evaporator. The primary concentrate is fed into the MVR evaporator through the feed pipeline for evaporation and concentration to obtain the secondary concentrate. A heating sodium precipitation device is fixedly installed above the MVR evaporator. The heating sodium precipitation device is used to further heat and crystallize the secondary concentrate to precipitate sodium chloride solid. A lithium precipitation reactor is provided, wherein a stirring tube is rotatably connected inside the reactor, a porous drum is fixedly installed above the stirring tube, the porous drum is used for centrifugal separation of lithium-rich solution, a liquid collecting cylinder is fixedly installed on the outside of the porous drum, multiple sets of liquid outlet holes are opened on the outer wall of the liquid collecting cylinder, a flow guiding baffle is fixedly installed below the liquid collecting cylinder, a slow release chamber is formed between the inner wall of the lithium precipitation reactor and the outer wall of the flow guiding baffle, the lithium-rich solution can flow into the slow release chamber through the multiple sets of liquid outlet holes, and multiple sets of liquid outlet pipes are fixedly installed at the bottom end of the flow guiding baffle. The feeding pipeline includes a spiral heat exchange tube, which is coiled around the outside of the flow guide ring and located inside the slow release chamber. The lithium-rich solution entering the slow release chamber can directly contact the spiral heat exchange tube, thereby exchanging heat with the primary concentrate inside the spiral heat exchange tube. The process of treating lithium-containing wastewater using the lithium-containing wastewater treatment equipment includes the following steps: S1. Pretreatment of high-chlorine lithium-containing wastewater: Adjust the pH of the high-chlorine lithium-containing wastewater to weakly acidic, and then filter to remove impurities and suspended solids from the water; S2. Reverse osmosis membrane separation: Dissolved salts in wastewater are separated using a membrane osmosis device to obtain primary concentrate and reclaimed water; S3, MVR evaporation and concentration: The primary concentrate is further evaporated and concentrated in an MVR evaporator to obtain a secondary concentrate; S4. Sodium precipitation and lithium separation: The secondary concentrate is transferred to a heated sodium precipitation device for further concentration, followed by centrifugation and filtration to obtain sodium chloride solid crystalline salt and lithium-rich solution. S5, Lithium carbonate precipitation: After the lithium-rich solution is cooled in the lithium precipitation reactor, a carbonate solution is added to react and generate lithium carbonate precipitate. The lithium carbonate product is then obtained by centrifugation and filtration. Before entering the MVR evaporator for evaporation and concentration, the primary concentrate can exchange heat with the lithium-rich solution through a spiral heat exchange tube in the lithium precipitation reactor, thereby preheating the primary concentrate and cooling the lithium-rich solution.

2. The lithium-containing wastewater treatment equipment according to claim 1, characterized in that, A base is fixedly installed below the lithium precipitation reactor. The base has a hollow structure inside and is used to store solid sodium chloride. The top end of the stirring tube is connected to the inside of the porous drum, and the bottom end of the stirring tube is connected to the inside of the hollow structure inside the base. The sodium chloride solid separated inside the porous drum can fall into the inside of the hollow structure through the stirring tube. A second solenoid valve is fixedly installed on the stirring tube near the top.

3. The lithium-containing wastewater treatment equipment according to claim 2, characterized in that, A first solenoid valve is fixedly installed near the bottom of the stirring tube. The first solenoid valve allows the sodium chloride solid entering the stirring tube to remain inside the stirring tube, and the heat of the sodium chloride solid is used to maintain the temperature of the lithium precipitation reaction.

4. The lithium-containing wastewater treatment equipment according to claim 3, characterized in that, A stirring motor is fixedly installed on the base. A belt is installed between the output end of the stirring motor and the stirring tube. The stirring motor can drive the stirring tube to rotate through the belt. Multiple sets of blades are fixedly installed on the stirring tube, which enables the stirring tube to stir during the lithium precipitation reaction.

5. The lithium-containing wastewater treatment equipment according to claim 4, characterized in that, A water distribution box is fixedly installed on the liquid collection cylinder, and multiple sets of nozzles are fixedly installed on the water distribution box; The MVR evaporator is fixedly equipped with a steam main pipe, and a steam branch pipe is connected to the steam main pipe. One end of the steam branch pipe is connected to the inside of the water distribution box. Steam is introduced into the inside of the water distribution box through the steam branch pipe and finally sprayed out through the nozzle to back-flushing and cleaning the multi-hole drum. Control valves are installed on both the main steam pipe and the branch steam pipe.

6. The lithium-containing wastewater treatment equipment according to claim 1, characterized in that, A helical toothed ring is rotatably connected to the outer wall of the liquid collecting cylinder, and a rotating sleeve is fixedly installed on the helical toothed ring. A control motor is fixedly installed on the lithium deposition reactor. The output end of the control motor extends into the interior of the lithium deposition reactor and is fixedly installed with a helical gear. The helical gear is matched with a helical gear ring. The liquid outlet includes multiple sets of internal liquid outlets formed on the liquid collecting cylinder and multiple sets of external liquid outlets formed on the rotating sleeve; The rotating sleeve is sealed and fitted to the outer wall of the liquid collecting cylinder, and the multiple sets of inner liquid outlet holes are respectively matched with the multiple sets of outer liquid outlet holes.

7. The lithium-containing wastewater treatment equipment according to claim 1, characterized in that, A dosing system is fixedly installed on the lithium precipitation reactor. The dosing system is connected to multiple sets of liquid outlet pipes, which can add carbonate solution to the lithium-rich solution through the multiple sets of liquid outlet pipes. The multiple sets of liquid outlet pipes have cavities inside, and multiple sets of bosses are fixedly installed on the inner wall of the liquid outlet pipes. The bosses have medicine outlet holes, and the cavity is connected to the inside of the liquid outlet pipe through the medicine outlet holes.

8. The lithium-containing wastewater treatment equipment according to claim 7, characterized in that, The dosing system includes a storage cylinder and a ring pipe. The storage cylinder is fixedly installed on the base, and a dosing pump is fixedly installed on the storage cylinder. The ring pipe is fixedly installed outside the lithium precipitation reactor, and a delivery pipe is fixedly installed between the output end of the dosing pump and the ring pipe; Multiple sets of injection tubes are fixedly installed on the ring tube, and the multiple sets of injection tubes are respectively connected to multiple sets of liquid outlet tubes.

9. The lithium-containing wastewater treatment equipment according to claim 1, characterized in that, The feeding pipeline also includes a concentrate pipe and a concentrate branch pipe. The concentrate pipe is fixedly installed between the primary membrane separation module and the MVR evaporator, and the concentrate branch pipe is fixedly installed between the secondary membrane separation module and the concentrate pipe. The spiral heat exchange tube is fixedly installed on the concentrate tube; A water pipe is fixedly installed between the primary membrane separation module and the secondary membrane separation module.

Images