Lithium cycle system for preparing lithium-enriched material

Abstract

The invention belongs to the field of inorganic enrichment materials, and discloses a lithium circulation system for preparing a lithium enrichment material, the lithium circulation system comprises a synthesis reaction kettle, a solid-liquid separation device, a lithium recovery module and an elution module, the lithium recovery module comprises an adsorption tower module and an evaporation crystallization module, the adsorption tower module is used for adsorbing lithium salt in high-lithium waste liquid and generating lithium-poor waste liquid, and the evaporation crystallization module is used for evaporating the lithium-poor waste liquid; the evaporative crystallization module is used for performing evaporative crystallization on the lithium-poor waste liquid and collecting corresponding alkali metal salt byproducts and condensate water, and the elution module is used for collecting the condensate water as a desorption solution for eluting and regenerating the adsorption tower module saturated in adsorption. According to the system, waste materials in the preparation process of the lithium-enriched material can be completely recycled, pollution emission is reduced, and economic benefits are improved.

Description

Technical Field

[0001] The invention belongs to the field of inorganic enrichment materials, and in particular relates to a lithium circulation system for preparing lithium enrichment materials. Background Art

[0002] An existing lithium-enriched material is formed by adding sodium hydroxide as an alkaline reagent to an aluminum chloride solution containing lithium ions in a reactor, and the reaction formula is: LiOH+3AlCl3+9NaOH+nH2O=LiCl·3Al(OH)3·nH2O+9NaCl, where 8≤n≤10; the LiCl·3Al(OH)3·nH2O precipitate is collected as the target lithium-enriched material product, and the filtrate containing sodium chloride and lithium chloride is filtered out as waste liquid.

[0003] However, the inventors found in the specific implementation that the lithium salt concentration in the above waste liquid is as high as 3-6g / L, and other by-products in the waste liquid system will not affect the reaction in the reactor, so the waste liquid can be directly fed into the reactor for the preparation of lithium-enriched materials after further recycling. If the by-products other than lithium salts are further separated and their purity reaches the predetermined standard, additional economic benefits can be generated, thereby achieving a win-win situation of cost reduction, efficiency improvement and environmental protection. Summary of the invention

[0004] The object of the present invention is to overcome at least one disadvantage of the prior art and provide a lithium circulation system for preparing lithium-enriched materials.

[0005] The technical solution adopted by the present invention is:

[0006] A lithium circulation system for preparing lithium-enriched materials comprises a synthesis reactor for generating lithium-enriched materials by using lithium salts, non-lithium metal salts and alkali metal hydroxides, and, after the reaction is completed, a solid-liquid separation device for filtering out high-lithium waste liquid in the synthesis reactor and separating the lithium-enriched materials; the lithium circulation system also comprises a lithium recovery module for extracting lithium salts from the high-lithium waste liquid and an elution module for eluting lithium salts from the lithium recovery module, the lithium recovery module comprises an adsorption tower module connected to the liquid outlet of the solid-liquid separation device and an evaporation crystallization module connected to the output end of the adsorption tower module, the adsorption tower module is used to adsorb lithium salts in the high-lithium waste liquid and generate lithium-poor waste liquid, the evaporation crystallization module evaporates and crystallizes the lithium-poor waste liquid, and collects corresponding alkali metal salt byproducts and condensed water, the input end of the elution module is used to collect the condensed water and the output end is correspondingly connected to the adsorption tower module, the condensed water is used as an analytical liquid to elute and regenerate the adsorption saturated adsorption tower module.

[0007] By separating lithium salts from high-lithium waste liquid for preparing lithium-enriched materials, the recovered lithium salts are used to return to the synthesis reactor for subsequent preparation of lithium-enriched materials, and the remaining aqueous solution of non-lithium metal salts in the waste liquid can be further evaporated and crystallized. The alkali metal salts after crystallization can be directly used as industrial-grade alkali metal salt products to achieve corresponding economic value, and the evaporated liquid is condensed and recovered to the elution module, which can be used for the elution adsorption tower module to achieve its regeneration. This system can achieve 100% recovery of waste materials in the preparation process of lithium-enriched materials, reduce pollution emissions, and improve economic benefits.

[0008] In some optional embodiments, the adsorption tower module comprises a plurality of adsorption towers, and 90% of the space in each of the adsorption towers is filled with the lithium enrichment material. The plurality of adsorption towers can be combined to form a multi-stage adsorption to increase the lithium salt recovery ratio, or adsorb and extract lithium in parallel to enhance the treatment efficiency of high-lithium waste liquid per unit time; the renewable lithium enrichment material of the target product of the synthesis reactor is used, and no additional feed is required, thereby reducing costs.

[0009] In some optional embodiments, the high-lithium waste liquid is adsorbed by one of the adsorption towers for 1-2 hours to generate low-lithium waste liquid, and the low-lithium waste liquid is adsorbed by at least one of the adsorption towers for 2-3 hours to generate the lithium-poor waste liquid, and the elution module elutes and regenerates one of the adsorption towers for 3-5 hours. By setting a reasonable time for adsorbing lithium salts in the waste liquid and the regeneration time for the adsorption tower, the adsorption tower can be alternately adsorbed and regenerated to achieve the optimal lithium recovery efficiency.

[0010] In some optional embodiments, the adsorption saturation of the adsorption tower for receiving the low-lithium waste liquid is not greater than the adsorption saturation of the adsorption tower for receiving the high-lithium waste liquid. As the adsorption saturation of the adsorption material increases, the adsorption efficiency gradually decreases. Therefore, the low-lithium waste liquid with a lower lithium salt content should be efficiently adsorbed using an adsorption tower with a lower saturation to improve the recovery rate of the lithium salt.

[0011] In some optional embodiments, the adsorption tower module includes a first adsorption tower and at least one second adsorption tower connected in series, and the adsorption tower module alternately performs a sequential adsorption procedure and a reverse adsorption procedure:

[0012] In the sequential adsorption procedure, the high-lithium waste liquid passes through the first adsorption tower and at least one of the second adsorption towers in sequence to generate the lithium-poor waste liquid;

[0013] In the reverse adsorption procedure, the high-lithium waste liquid passes through at least one of the second adsorption tower and the first adsorption tower in sequence to generate the lithium-poor waste liquid.

[0014] The adsorption tower module performs sequential adsorption and reverse adsorption alternately. In the initial state, the high-lithium waste liquid is subjected to sequential adsorption, and in the adjacent reverse adsorption process, more time can be reserved for the elution module to regenerate the first adsorption tower, and in the adjacent sequential adsorption process, more time can be reserved for elution regeneration of the second adsorption tower.

[0015] In some optional embodiments, the first adsorption tower and the second adsorption tower are configured to perform elution and regeneration of the lithium-enriched material once after completing two adsorption and filtration of lithium salts. Each adsorption tower adsorbs twice to reach saturation, and elutes and regenerates in time to ensure that the lithium salt content in the lithium-poor waste liquid after each adsorption process is below a predetermined standard.

[0016] In some optional embodiments, the second adsorption tower is set to one, and before the adsorption tower performs the sequential adsorption procedure for the first time, the first adsorption tower needs to pre-receive the high-lithium waste liquid once to generate the low-lithium waste liquid, and before the low-lithium waste liquid enters the second adsorption tower, the adsorption tower starts the sequential adsorption procedure. By allowing the first adsorption tower to pre-receive the high-lithium waste liquid once, the saturation difference with the first adsorption of the second adsorption tower is achieved, so that in the subsequent alternating sequence and reverse adsorption procedures, the first adsorption tower or the second adsorption tower into which the low-lithium waste liquid enters is always a brand-new lithium-enriched material that has not been adsorbed by lithium salts or has just been regenerated, thereby achieving a better adsorption and recovery effect on the low-lithium waste liquid with a relatively lower lithium salt concentration, thereby achieving a lithium-poor waste liquid with a lower residual lithium salt concentration, and further improving the purity of the by-product alkali metal salt, the chemical quality of the alkali metal salt is also improved, and better economic value can be created.

[0017] In some optional embodiments, from the time when the low-lithium waste liquid in the sequential adsorption process is completely filtered out of the first adsorption tower to the time when the low-lithium waste liquid in the adjacent reverse adsorption process enters the first adsorption tower, the elution module injects the analytical solution into the first adsorption tower to elute and regenerate the lithium-enriched material in the first adsorption tower;

[0018] From the time when the low-lithium waste liquid in the reverse adsorption process is completely filtered out of the second adsorption tower to the time when the low-lithium waste liquid in the adjacent sequential adsorption process enters the second adsorption tower, the elution module injects the analysis liquid into the second adsorption tower to elute and regenerate the lithium-enriched material in the second adsorption tower.

[0019] Rationally utilize the time of the adsorption tower that is not occupied by lithium-containing waste liquid, and cross-use the elution modules for elution and regeneration of lithium-enriched materials in the adsorption tower, improve the smoothness of system operation, and ensure lithium recovery efficiency.

[0020] In some optional embodiments, the lithium salt concentration of the low-lithium waste liquid is 1.8-2.4 g / L, and the lithium salt concentration of the poor-lithium waste liquid is 0.15-0.3 g / L. The efficiency of the two adsorptions of the equilibrium adsorption tower is adapted to the configuration of the adsorption tower module.

[0021] In some optional embodiments, the lithium circulation system further includes a lithium salt concentration module, the input end of which receives the eluate after the elution module elutes the adsorption tower, and the output end feeds the synthesis reactor to filter and concentrate the lithium salt raw material obtained by the eluate, and injects the water obtained by filtering and concentrating the eluate into the elution module. The lithium salt raw material suitable for the synthesis reactor can be obtained by simply concentrating the eluate, and the circulation of the lithium salt full circuit is completely realized, achieving both zero emission and high efficiency.

[0022] In some optional embodiments, the lithium salt concentration of the eluent is 5-9 g / L, and the lithium salt concentration of the lithium salt raw material obtained by filtering and concentrating by the lithium salt concentration module is 30 g / L. The lithium salt concentration of the concentrated lithium salt raw material meets the production requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a lithium circulation system for preparing lithium-enriched materials according to an optional embodiment of the present application.

[0024] Among them, the blue pipeline reflects the route of high-lithium waste liquid from the first adsorption tower to the evaporation crystallization module in the sequential adsorption procedure; the red pipeline reflects the route of high-lithium waste liquid from the second adsorption tower to the evaporation crystallization module in the reverse adsorption procedure; the green pipeline reflects the route of the analytical liquid elution and regeneration of the first adsorption tower and the second adsorption tower in the elution module. DETAILED DESCRIPTION

[0025] Embodiments of the present embodiment are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment, and should not be construed as limiting the present embodiment.

[0026] In the description of this embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this embodiment.

[0027] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0028] In the description of this embodiment, unless otherwise clearly defined, the terms such as setting, installing, connecting, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in this embodiment in combination with the specific content of the technical solution. The technical solution of the present invention is further described below in combination with exemplary embodiments.

[0029] The present application provides a lithium circulation system for preparing lithium-enriched materials, comprising a synthesis reactor for generating lithium-enriched materials using lithium salts, non-lithium metal salts and alkali metal hydroxides, and, after the reaction is completed, a solid-liquid separation device for filtering out high-lithium waste liquid in the synthesis reactor and separating the lithium-enriched materials; the lithium circulation system also includes a lithium recovery module for extracting lithium salts from the high-lithium waste liquid and an elution module for eluting lithium salts from the lithium recovery module, the lithium recovery module includes an adsorption tower module connected to the liquid outlet of the solid-liquid separation device and an evaporation crystallization module connected to the output end of the adsorption tower module, the adsorption tower module is used to adsorb lithium salts in the high-lithium waste liquid and generate lithium-poor waste liquid, the evaporation crystallization module evaporates and crystallizes the lithium-poor waste liquid, and collects corresponding alkali metal salt by-products and condensed water, the input end of the elution module is used to collect the condensed water and the output end is correspondingly connected to the adsorption tower module, and the condensed water is used as an analytical liquid to elute and regenerate the adsorption saturated adsorption tower module.

[0030] For example, see Figure 1 , lithium hydroxide is used as the lithium salt raw material, aluminum chloride is used as the non-lithium metal salt, and sodium hydroxide is used as the alkali metal hydroxide. Therefore, in the synthesis reactor, sodium hydroxide is added as an alkaline reagent to the aluminum chloride solution containing lithium ions to form aluminum lithium double hydroxide, and the aluminum lithium double hydroxide is also used as a lithium enrichment material, and the reaction formula is: LiOH+3AlCl3+9NaOH+nH2O=LiCl·3Al(OH)3·nH2O+9NaCl, where 8≤n≤10; after the reaction is completed, a slurry containing LiCl·3Al(OH)3·nH2O precipitate is formed, and then solid-liquid separation is performed through solid-liquid separation equipment such as a filter press, wherein the solid is collected as the target lithium enrichment material product, and the filtrate is filtered out as a waste liquid containing sodium chloride and lithium chloride.

[0031] Furthermore, the waste liquid filtered out by the solid-liquid separation equipment is used as the high-lithium waste liquid to be treated, and a lithium recovery module is set up. The high-lithium waste liquid is output as a lithium-poor waste liquid through the adsorption tower module in the lithium recovery module, and the lithium-poor waste liquid is received by the evaporation and crystallization module for further solid-liquid separation in the form of evaporation and crystallization to obtain alkali metal salt by-products and condensed water, wherein the by-product alkali metal salt can be directly used as an industrial raw material for application or sale, and the condensed water is collected in the elution module and used as a decomposition liquid for the adsorption material in the elution adsorption tower. The waste materials in the preparation process of lithium-enriched materials in this system can be recycled and reused 100%, achieving 0 emissions and improving economic benefits. It can be understood that the concentration of lithium salts in the lithium-poor waste liquid needs to be within the impurity control requirements of the industrial purity of alkali metal salts, and the condensed water is not enough to completely cover the water consumption of the elution module, so the elution module should also be connected to external water.

[0032] In some optional embodiments, the adsorption tower module includes multiple adsorption towers, and 90% of the space in each of the adsorption towers is filled with the target product of the lithium-enriched material prepared by the synthesis reactor. There is no need to purchase additional lithium-enriched materials to realize the production of the adsorption tower, which reduces the cost. Multiple adsorption towers can be set up. On the one hand, they can be combined to form a multi-stage adsorption to increase the lithium salt recovery ratio. On the other hand, multiple adsorption towers are parallel to adsorb and extract lithium, which enhances the treatment efficiency of high-lithium waste liquid per unit time. It can be understood that, on the one hand, the lithium-enriched material separated by the solid-liquid separation equipment needs to be further processed into lithium-enriched particles to be filled into the adsorption tower, and the size of the lithium-enriched particles will affect the upper limit of the space filling ratio of the adsorption tower, so it is necessary to screen out a suitable particle size, which will not be repeated here; on the other hand, there is a certain start-up sequence between the synthesis reactor, the lithium salt recovery module and the elution module in this system, wherein the synthesis reactor pre-reacts to generate a certain amount of lithium-enriched material and a predetermined amount of high-lithium waste liquid, and then the lithium recovery module is started to fill the lithium-enriched material, build the pipeline and adsorb the high-lithium waste liquid, and the elution module can be arranged in advance and set to standby.

[0033] Furthermore, the high-lithium waste liquid is adsorbed by one of the adsorption towers for 1-2 hours to generate low-lithium waste liquid, and the low-lithium waste liquid is adsorbed by at least one of the adsorption towers for 2-3 hours to generate the lithium-poor waste liquid, and the elution module elutes and regenerates one of the adsorption towers for 3-5 hours. By setting a reasonable time for adsorbing lithium salts in the waste liquid and the regeneration time for the adsorption tower, the adsorption tower can be alternately adsorbed and regenerated to achieve the optimal lithium recovery efficiency. The low-lithium waste liquid has a low lithium salt content, and it is more difficult for the lithium-enriched material to capture the lithium salt. Therefore, appropriately extending the treatment time of the low-lithium waste liquid is also conducive to improving the recovery rate of the lithium salt.

[0034] Furthermore, the adsorption saturation of the adsorption tower for receiving the low-lithium waste liquid is not greater than the adsorption saturation of the adsorption tower for receiving the high-lithium waste liquid. For multi-stage adsorption operation, the high-lithium waste liquid becomes low-lithium waste liquid after the first-stage adsorption, and the lithium salt concentration drops significantly. The rule of lithium-enriched materials is that as the adsorption saturation of the material increases, the adsorption efficiency of the material will gradually decrease. Therefore, the low-lithium waste liquid should be treated with an adsorption tower with a lower adsorption saturation, so as to achieve efficient adsorption and improve the recovery rate of lithium salts. In addition, a new adsorption tower with a saturation of 0 can also be used to treat the waste liquid throughout the process. At this time, the saturation of each adsorption tower is 0.

[0035] In some optional embodiments, the adsorption tower module includes a first adsorption tower and at least one second adsorption tower connected in series, and the adsorption tower module alternately performs a sequential adsorption procedure and a reverse adsorption procedure:

[0036] In the sequential adsorption procedure, the high-lithium waste liquid passes through the first adsorption tower and at least one of the second adsorption towers in sequence to generate the lithium-poor waste liquid;

[0037] In the reverse adsorption procedure, the high-lithium waste liquid passes through at least one of the second adsorption tower and the first adsorption tower in sequence to generate the lithium-poor waste liquid.

[0038] The adsorption tower module performs sequential adsorption and reverse adsorption alternately. In the initial state, the high-lithium waste liquid is subjected to sequential adsorption, and in the adjacent reverse adsorption process, more time can be reserved for the elution module to regenerate the first adsorption tower, and in the adjacent sequential adsorption process, more time can be reserved for elution regeneration of the second adsorption tower.

[0039] It can be understood that the first adsorption tower is connected to the solid-liquid separation equipment, the second adsorption tower and the elution module through corresponding pipelines. In order to achieve better control, each pipeline should be equipped with a corresponding valve, and the valve between the first adsorption tower and the second adsorption tower should also be a two-way valve.

[0040] For example, see Figure 1 , the second adsorption tower is set to 1, and before the adsorption tower performs the sequential adsorption procedure for the first time, the first adsorption tower needs to pre-receive the high-lithium waste liquid once to generate the low-lithium waste liquid, and before the low-lithium waste liquid enters the second adsorption tower, the adsorption tower starts the sequential adsorption procedure. Among them, between the first adsorption tower pre-receiving the high-lithium waste liquid and the first adsorption tower receiving the high-lithium waste liquid for the second time, the valve between the first adsorption tower and the second adsorption tower should be closed. It is understandable that the pipeline between the first adsorption tower and the second adsorption tower may not be sufficient to accommodate the low-lithium waste liquid generated by receiving the high-lithium waste liquid once, so it may be necessary to install a buffer tank for storing the low-lithium waste liquid in the pipeline.

[0041] By making the first adsorption tower pre-receive a high-lithium waste liquid, a saturation difference with the first adsorption of the second adsorption tower is achieved, so that in the subsequent alternating order and reverse adsorption procedures, and it is well known that as the adsorption saturation of the adsorption material increases, the adsorption efficiency will gradually decrease. Therefore, the low-lithium waste liquid is always given priority to enter the first adsorption tower or the second adsorption tower of brand-new lithium-enriched materials that have not been adsorbed by lithium salts or have just been regenerated, thereby achieving a better adsorption and recovery effect on low-lithium waste liquid with relatively lower lithium salt concentration, thereby achieving lithium-poor waste liquid with lower residual lithium salt concentration, and further improving the purity of the by-product alkali metal salt, the chemical quality of the alkali metal salt is also improved, and can create better economic value.

[0042] Furthermore, the first adsorption tower and the second adsorption tower are configured to perform elution and regeneration of the lithium-enriched material after completing two adsorption and filtration of lithium salts. Exemplarily, the saturation of the lithium-enriched material reaches 50% after one adsorption by each adsorption tower, and the saturation is 100% after two adsorptions. Therefore, each adsorption tower reaches saturation after two adsorptions, and needs to be eluted and regenerated in time to ensure that the lithium salt content in the lithium-poor waste liquid after each adsorption procedure is below the predetermined standard, thereby meeting the purity requirements of the by-product alkali metal salt. The specific status data of the lithium recovery module and the elution module in specific operation are shown in the table below:

[0043]

[0044] The above table demonstrates the pre-receiving procedure and the two alternating sequential adsorption procedures and the reverse adsorption procedure. It can be seen that the adsorption tower that the low-lithium waste liquid passes through each time is an adsorption tower filled with newly-filled lithium-enriched materials or regenerated new lithium-enriched materials to achieve better adsorption.

[0045] In some optional embodiments, from the time when the low-lithium waste liquid in the sequential adsorption process is completely filtered out of the first adsorption tower to the time when the low-lithium waste liquid in the adjacent reverse adsorption process enters the first adsorption tower, the elution module injects the analytical solution into the first adsorption tower to elute and regenerate the lithium-enriched material in the first adsorption tower;

[0046] From the time when the low-lithium waste liquid in the reverse adsorption process is completely filtered out of the second adsorption tower to the time when the low-lithium waste liquid in the adjacent sequential adsorption process enters the second adsorption tower, the elution module injects the analysis liquid into the second adsorption tower to elute and regenerate the lithium-enriched material in the second adsorption tower.

[0047] Rationally utilize the time of the adsorption tower that is not occupied by lithium-containing waste liquid, and cross-use the elution modules for elution and regeneration of lithium-enriched materials in the adsorption tower, improve the smoothness of system operation, and ensure lithium recovery efficiency.

[0048] In some optional embodiments, the lithium salt concentration of the low-lithium waste liquid is 1.8-2.4 g / L, and the lithium salt concentration of the poor-lithium waste liquid is 0.15-0.3 g / L. The efficiency of the two adsorptions of the equilibrium adsorption tower is compatible with the configuration of the adsorption tower module, and compared with the original high-lithium waste liquid, 97.5% of the lithium salt can be recovered, which not only ensures the purity of the by-products, but also improves the utilization rate of the lithium salt raw materials.

[0049] In some optional embodiments, the lithium circulation system further includes a lithium salt concentration module, the input end of the lithium salt concentration module receives the eluate after the elution module elutes the adsorption tower, and the output end feeds the synthesis reactor to filter and concentrate the lithium salt raw material obtained by the eluate and injects the water obtained by filtering and concentrating the eluate into the elution module. By simply concentrating the eluate, a lithium salt raw material suitable for the synthesis reactor can be obtained, and the circulation of the lithium salt full circuit can be fully realized, with zero emissions and high efficiency; and the filtered water can be further returned to the elution module as a analytical solution, which can be fully recycled. In the specific implementation process, a common RO filtration device can be used as the lithium salt concentration module to simply and efficiently filter and concentrate the lithium salt, and the permeated water molecules are directly transported to the elution module.

[0050] In some optional embodiments, the lithium salt concentration of the eluent is 5-9 g / L, and the lithium salt concentration of the lithium salt raw material obtained by filtering and concentrating by the lithium salt concentration module is 30 g / L. The lithium salt concentration of the concentrated lithium salt raw material meets the production requirements.

[0051] The above is a further detailed description of the present invention, which should not be regarded as a limitation on the specific implementation of the present invention. For ordinary technicians in the technical field to which the present invention belongs, simple deduction or replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A lithium circulation system for preparing lithium-enriched materials, comprising a synthesis reactor for generating lithium-enriched materials using lithium salts, non-lithium metal salts and alkali metal hydroxides, and, after the reaction is completed, a solid-liquid separation device for filtering out high-lithium waste liquid in the synthesis reactor to separate the lithium-enriched materials; characterized in that: The lithium circulation system also includes a lithium recovery module for extracting lithium salts from the high-lithium waste liquid and an elution module for eluting lithium salts from the lithium recovery module. The lithium recovery module includes an adsorption tower module connected to the liquid outlet of the solid-liquid separation device and an evaporation crystallization module connected to the output end of the adsorption tower module. The adsorption tower module is used to adsorb lithium salts in the high-lithium waste liquid and generate lithium-poor waste liquid. The evaporation crystallization module evaporates and crystallizes the lithium-poor waste liquid to collect corresponding alkali metal salt by-products and condensed water. The input end of the elution module is used to collect the condensed water and the output end is correspondingly connected to the adsorption tower module. The condensed water is used as an analytical liquid to elute and regenerate the adsorption saturated adsorption tower module.

2. The lithium circulation system for preparing lithium-enriched materials according to claim 1, characterized in that: The adsorption tower module comprises a plurality of adsorption towers, and 90% of the space in each of the adsorption towers is filled with the lithium-enriched material.

3. The lithium circulation system for preparing lithium-enriched materials according to claim 2, characterized in that: The high-lithium waste liquid is adsorbed in one of the adsorption towers for 1-2 hours to generate low-lithium waste liquid, and the low-lithium waste liquid is adsorbed in at least one more adsorption tower for 2-3 hours to generate the lithium-poor waste liquid. The elution module takes 3-5 hours to regenerate one of the adsorption towers.

4. The lithium circulation system for preparing lithium-enriched materials according to claim 3, characterized in that: The adsorption saturation of the adsorption tower for receiving the low-lithium waste liquid is not greater than the adsorption saturation of the adsorption tower for receiving the high-lithium waste liquid.

5. The lithium circulation system for preparing lithium-enriched materials according to claim 3, characterized in that: The adsorption tower module comprises a first adsorption tower and at least one second adsorption tower connected in series, and the adsorption tower module alternately performs a sequential adsorption procedure and a reverse adsorption procedure: In the sequential adsorption procedure, the high-lithium waste liquid passes through the first adsorption tower and at least one of the second adsorption towers in sequence to generate the lithium-poor waste liquid; In the reverse adsorption procedure, the high-lithium waste liquid passes through at least one of the second adsorption tower and the first adsorption tower in sequence to generate the lithium-poor waste liquid.

6. The lithium circulation system for preparing lithium-enriched materials according to claim 5, characterized in that: The first adsorption tower and the second adsorption tower are configured to perform elution and regeneration of the lithium-enriched material once after completing two adsorption and filtration of lithium salts.

7. The lithium circulation system for preparing lithium-enriched materials according to claim 5 or 6, characterized in that: The second adsorption tower is set to one. Before the adsorption tower executes the sequential adsorption program for the first time, the first adsorption tower needs to pre-receive the high-lithium waste liquid once to generate the low-lithium waste liquid, and before the low-lithium waste liquid enters the second adsorption tower, the adsorption tower starts the sequential adsorption program.

8. The lithium circulation system for preparing lithium-enriched materials according to claim 7, characterized in that: From the time when the low-lithium waste liquid in the sequential adsorption process is completely filtered out of the first adsorption tower to the time when the low-lithium waste liquid in the adjacent reverse adsorption process enters the first adsorption tower, the elution module injects the analytical solution into the first adsorption tower to elute and regenerate the lithium-enriched material in the first adsorption tower; From the time when the low-lithium waste liquid in the reverse adsorption process is completely filtered out of the second adsorption tower to the time when the low-lithium waste liquid in the adjacent sequential adsorption process enters the second adsorption tower, the elution module injects the analysis liquid into the second adsorption tower to elute and regenerate the lithium-enriched material in the second adsorption tower.

9. The lithium circulation system for preparing lithium-enriched materials according to claim 3, characterized in that: The lithium salt concentration of the low-lithium waste liquid is 1.8-2.4 g / L, and the lithium salt concentration of the poor-lithium waste liquid is 0.15-0.3 g / L.

10. The lithium circulation system for preparing lithium-enriched materials according to claim 1, characterized in that: The lithium circulation system also includes a lithium salt concentration module, the input end of the lithium salt concentration module receives the eluate after the elution module elutes the adsorption tower, and the output end feeds the lithium salt raw material obtained by filtering and concentrating the eluate into the synthesis reactor and injects the water obtained by filtering and concentrating the eluate into the elution module.

11. The lithium circulation system for preparing lithium-enriched materials according to claim 10, characterized in that: The lithium salt concentration of the eluent is 5-9 g / L, and the lithium salt concentration of the lithium salt raw material obtained by filtration and concentration by the lithium salt concentration module is 30 g / L.

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