Resource utilization method of lithium-containing mother liquor and resource utilization device of lithium-containing mother liquor

Abstract

The invention provides a resource utilization method of a lithium-containing mother solution and a resource utilization device of the lithium-containing mother solution. The resource utilization method of the lithium-containing mother liquor comprises the following steps: providing the lithium-containing mother liquor containing lithium ions and sulfate ions; mixing the lithium-containing mother solution with a phosphate solution, and performing lithium precipitation treatment to obtain lithium-containing slurry; carrying out solid-liquid separation treatment on the lithium-containing slurry to obtain pre-adsorption liquid and a first solid material; adsorbing lithium ions in the adsorption pre-solution by adopting a titanium adsorbent to obtain an adsorption tail solution; and carrying out concentration and crystallization treatment on the adsorption tail liquid, wherein the ratio of the amount of substance of lithium ions in the lithium-containing mother solution to the amount of substance of phosphate ions in the phosphate solution is 3: (0.7-0.8). The resource utilization method of the lithium-containing mother liquor can improve the lithium recovery rate and the purity of the recovered product.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a resource utilization method and a resource utilization system of lithium-containing mother liquor. Background Art

[0002] Lithium mother liquor is a lithium-containing mother liquor formed after lithium salts are extracted from lithium ore or from waste lithium iron phosphate batteries. It contains not only a certain amount of lithium ions, but also a large amount of impurities, such as carbonate ions, sulfate ions, aluminum ions, calcium ions and sodium ions. The lithium content in lithium mother liquor accounts for more than 20% of the entire lithium extraction material circulation process, so it is necessary to recover the lithium ions in lithium mother liquor.

[0003] Some traditional technologies propose to use adsorbent adsorption to recover lithium ions from lithium precipitation mother liquor. However, the lithium adsorption rate of this extraction method is usually only 85%~90%. In addition, the adsorbent will gradually wear out during use, which is costly and requires larger adsorption equipment. Some other traditional technologies propose to add solid phosphate to lithium precipitation mother liquor to generate lithium phosphate precipitate to recover lithium ions. This extraction method requires the addition of excess phosphate to recover more lithium, and the recovery rate of lithium element can only reach 70%~80%. The obtained lithium phosphate precipitate contains more impurities, and the low concentration of lithium element in the remaining liquid is difficult to further recover.

[0004] Based on the above situation, further research is still needed to provide a method for resource utilization of lithium-containing mother liquor and a device for resource utilization of lithium-containing mother liquor. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a method for resource utilization of lithium-containing mother liquor and a device for resource utilization of lithium-containing mother liquor, which are beneficial to improving the recovery rate of lithium elements and improving the purity of recovered products.

[0006] The embodiment of the present application provides a method for resource utilization of lithium-containing mother solution, which comprises the following steps:

[0007] providing a lithium-containing mother solution containing lithium ions and sulfate ions;

[0008] The lithium-containing mother solution is mixed with a phosphate solution and then subjected to lithium precipitation treatment to obtain a lithium-containing slurry;

[0009] The lithium-containing slurry is subjected to solid-liquid separation to obtain a pre-adsorption liquid and a first solid material;

[0010] Adsorbing lithium ions in the pre-adsorption liquid with an adsorbent to obtain an adsorption tail liquid; and,

[0011] The adsorption tail liquid is concentrated and crystallized to obtain a second solid material;

[0012] The molar ratio of lithium ions in the lithium-containing mother solution to phosphate ions in the phosphate solution is 3:(0.7-0.8).

[0013] In the resource utilization method of the lithium-containing mother liquor, the lithium-containing mother liquor is first mixed with a phosphate solution, and the feeding ratio of lithium ions to phosphate ions is controlled to be 3: (0.7~0.8) during mixing. The amount of phosphate ions in this feeding ratio is relatively low, which is conducive to improving the peritectic problem and improving the purity of lithium phosphate in the first solid material while precipitating a large amount of lithium ions. Furthermore, the lithium precipitation treatment consumes most of the lithium ions in the lithium-containing mother liquor, thereby effectively alleviating the problem of reduced alkalinity during the subsequent adsorption process, and significantly improving the adsorption capacity of the adsorbent for lithium ions. After the above-mentioned lithium precipitation treatment and lithium ion adsorption, more than 99% of the lithium ions in the lithium-containing mother liquor are recovered, and the impurities remaining in the adsorption tail liquid are relatively small. The purity of the sulfate material obtained by the concentration and crystallization treatment of the adsorption tail liquid is relatively high.

[0014] In some embodiments of the present application, during the process of mixing the lithium-containing mother solution with the phosphate solution, the lithium-containing mother solution is added to the phosphate solution.

[0015] In this embodiment, the reverse feeding method of adding the lithium-containing mother liquor into the phosphate solution is adopted, which is beneficial to effectively avoid the peritectic problem and promote more complete precipitation of lithium ions, thereby further improving the purity of lithium phosphate in the first solid material and the recovery rate of lithium ions.

[0016] In some embodiments of the present application, the lithium-containing mother solution is added to the phosphate solution within 0.5 h to 4 h.

[0017] In this embodiment, the lithium-containing mother solution is added to the phosphate solution within 0.5 h to 4 h, which is beneficial for the full crystallization and growth of lithium phosphate and improves the purity of lithium phosphate in the obtained first solid material.

[0018] In some embodiments of the present application, the phosphate in the phosphate solution includes one or more of sodium dihydrogen phosphate and disodium hydrogen phosphate.

[0019] In this embodiment, sodium dihydrogen phosphate and disodium hydrogen phosphate have high solubility. Using sodium dihydrogen phosphate and disodium hydrogen phosphate as solutes in the phosphate solution is beneficial to reducing the required volume of the phosphate solution, reducing the dilution of lithium ions during the feeding process, and facilitating the full precipitation of lithium ions; and sodium dihydrogen phosphate and disodium hydrogen phosphate can also produce hydrogen ions, which is beneficial to adjusting the pH value after the lithium precipitation reaction to an appropriate range, reducing or avoiding the use of additional acid-base regulators.

[0020] In some embodiments of the present application, the phosphate solution is a saturated solution of phosphate ions.

[0021] In this embodiment, compared with an unsaturated solution, a saturated solution of phosphate ions is used as the phosphate, and lithium ions can combine and precipitate with the phosphate ions more quickly and more fully, which is conducive to obtaining a higher lithium ion recovery rate and resource utilization efficiency.

[0022] In some embodiments of the present application, after the solid-liquid separation process, a step of washing the first solid material with a washing liquid is also included.

[0023] In some embodiments of the present application, before mixing the lithium-containing mother solution with the phosphate solution, the lithium-containing mother solution is heated to 80° C. to 100° C.; and / or,

[0024] The temperature of the lithium precipitation treatment is 80° C. to 100° C., and the insulation time of the lithium precipitation treatment is 2 h to 4 h.

[0025] In this embodiment, the lithium-containing mother solution is heated to 80°C to 100°C and the temperature of the lithium precipitation treatment is controlled to be 80°C to 100°C, which is conducive to the rapid and sufficient precipitation of lithium ions and phosphate ions in the lithium-containing mother solution, and is conducive to improving the efficiency of resource utilization and the recovery rate of lithium ions. Controlling the holding time to be within 2h to 4h is conducive to the full crystallization and crystal growth of lithium phosphate, and is conducive to further improving the purity of lithium phosphate in the obtained first solid material.

[0026] In some embodiments of the present application, the pH value of the pre-adsorption solution is 9.5-10.5.

[0027] In this embodiment, a pre-adsorption liquid with a pH value of 9.5-10.5 is used to provide sufficient alkalinity for the adsorption of lithium ions by the adsorbent so that the lithium ions can be fully adsorbed, which is beneficial to avoid the dissolution problem of the adsorbent during the adsorption process and increase the service life of the adsorbent.

[0028] In some embodiments of the present application, the lithium ion concentration in the pre-adsorption liquid is 200 ppm to 500 ppm, and the lithium ion concentration in the adsorption tail liquid is less than 20 ppm.

[0029] In this embodiment, the lithium ion concentration in the pre-adsorption liquid is controlled to be 200ppm~500ppm and the lithium ion concentration in the adsorption tail liquid is less than 20ppm, which is conducive to the adsorbent fully adsorbing lithium ions and controlling the loss of the adsorbent, thereby reducing the use cost of the adsorbent.

[0030] In some embodiments of the present application, the adsorbent includes a titanium-based adsorbent, and after the adsorbent is used to adsorb lithium ions in the pre-adsorption liquid, the process further includes: using an acid solution to desorb the adsorbent.

[0031] In this embodiment, the adsorbent is desorbed by an acid solution to form a lithium solution enriched with lithium ions, which is beneficial to further recovery and utilization of lithium elements.

[0032] In some embodiments of the present application, the phosphate solution contains sodium ions, and before the adsorption tail liquid is concentrated and crystallized, it also includes: adjusting the pH value of the adsorption tail liquid to 5.0~6.0; the step of concentrating and crystallizing the adsorption tail liquid includes: sequentially performing evaporation concentration treatment and freeze crystallization treatment on the adsorption tail liquid to obtain the second solid material and the crystal residual liquid; the second solid material is dried to obtain alum.

[0033] In this embodiment, adjusting the pH value of the adsorption tail liquid is beneficial to improving the purity of sodium sulfate in the second solid material; using the evaporation concentration treatment and the freezing crystallization treatment in sequence is beneficial to improving the recovery rate of glauber salt.

[0034] In some embodiments of the present application, the method further includes: preparing the crystallization residual solution into a phosphate solution, and recycling the solution to mix the lithium-containing mother solution with the phosphate solution.

[0035] In this embodiment, the lithium ions and sulfate ions in the crystallization residual liquid have been basically removed, so mainly a small amount of phosphate ions remain in the crystallization residual liquid. Reusing them in the phosphate solution will not affect the recovery rate of lithium ions and sulfate ions, but will also help to fully utilize the phosphate ions and save the cost of resource utilization.

[0036] In some embodiments of the present application, the lithium ion concentration in the lithium-containing mother solution is 1450ppm~2700ppm; and / or,

[0037] The lithium-containing mother liquor is selected from the lithium-precipitated mother liquor of waste lithium iron phosphate batteries or the lithium-precipitated mother liquor produced by extracting lithium from lithium ore.

[0038] In this embodiment, the resource utilization method is targeted at recovering a specific lithium-containing mother liquor, the cost of the required raw materials is relatively low, the recovery efficiency is relatively high, and the residual lithium ions therein can be recovered more fully, thus having a high economic benefit.

[0039] The present application also provides a resource utilization device for lithium-containing mother liquor, which includes: a lithium precipitation reactor, a solid-liquid separator, an adsorber, an evaporator and a cooling crystallizer; wherein the discharge port of the lithium precipitation reactor is connected to the feed port of the solid-liquid separator, the discharge port of the solid-liquid separator is connected to the feed port of the adsorber, an adsorbent is arranged in the adsorber, the discharge port of the adsorber is connected to the feed port of the evaporator, and the discharge port of the evaporator is connected to the feed port of the cooling crystallizer.

[0040] The resource utilization device of the lithium-containing mother solution is used to implement the resource utilization method of the lithium-containing mother solution as described in the above embodiment.

[0041] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 A schematic diagram of the steps of a method for resource utilization of lithium-containing mother liquor in the present application;

[0044] Figure 2 This is a process flow chart of a method for resource utilization of lithium-containing mother liquor in the present application. DETAILED DESCRIPTION

[0045] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0047] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0050] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0051] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0052] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0053] In the examples of the present application, ppm represents the ratio of the mass of the solute to the mass of the solution.

[0054] In the embodiments of the present application, unless otherwise specified, the solvents of "mother liquor", "solution", "tail liquor", "pre-adsorption liquid", "acid liquid", "residual liquid", etc. are independently selected from at least one of secondary water, deionized water, distilled water, pure water and ultrapure water.

[0055] The present application provides a method for resource utilization of lithium-containing mother liquor, which comprises the following steps: providing a lithium-containing mother liquor containing lithium ions and sulfate ions;

[0056] The lithium-containing mother liquor is mixed with a phosphate solution and then subjected to lithium precipitation treatment to obtain a lithium-containing slurry;

[0057] The lithium-containing slurry is subjected to solid-liquid separation treatment to obtain a pre-adsorption liquid and a first solid material;

[0058] Adsorbing lithium ions in the pre-adsorption liquid using a titanium-based adsorbent to obtain an adsorption tail liquid; and,

[0059] The adsorption tail liquid is concentrated and crystallized;

[0060] Among them, the molar ratio of lithium ions in the lithium-containing mother solution to phosphate ions in the phosphate solution is 3: (0.7~0.8).

[0061] In the resource utilization method of the lithium-containing mother liquor, the lithium-containing mother liquor is first mixed with a phosphate solution, and the feeding ratio of lithium ions to phosphate ions is controlled to be 3: (0.7~0.8) during mixing. The amount of phosphate ions in the feeding ratio is relatively low, which is conducive to improving the peritectic problem and improving the purity of lithium phosphate in the first solid material while precipitating a large amount of lithium ions. When the amount of phosphate ions is greater than 0.8, it will not only increase the cost of resource utilization, but also introduce too many phosphate ions into the pre-adsorption liquid, which is not conducive to subsequent adsorption and concentrated crystallization. Further, the lithium precipitation treatment consumes most of the lithium ions in the lithium-containing mother liquor, thereby effectively alleviating the problem of reduced alkalinity during the subsequent adsorption process, and significantly improving the adsorption capacity of the adsorbent for lithium ions. After the above-mentioned lithium precipitation treatment and lithium ion adsorption, more than 99% of the lithium ions in the lithium-containing mother liquor are recovered, and the impurities remaining in the adsorption tail liquid are relatively small, and the purity of the sulfate material obtained by the adsorption tail liquid through concentrated crystallization treatment is relatively high.

[0062] Figure 1 This is a schematic diagram of the steps of a method for resource utilization of lithium-containing mother liquor in this application. Figure 1 As shown, the resource utilization method of the lithium-containing mother solution includes the following steps S1 to S5, which are specifically as follows.

[0063] Step S1, providing a lithium-containing mother solution containing lithium ions and sulfate ions.

[0064] As an example of this embodiment, the lithium ion concentration in the lithium-containing mother solution is 1450ppm to 2700ppm. For example, the lithium ion concentration in the lithium-containing mother solution may be 1450ppm, 1500ppm, 1600ppm, 1800ppm, 2000ppm, 2200ppm, 2400ppm, 2500ppm, 2600ppm or 2700ppm, or the lithium ion concentration in the lithium-containing mother solution may be between any two of the above concentrations.

[0065] As an example of this embodiment, the sulfate ion concentration in the lithium-containing mother solution is 80 g / L to 105 g / L. For example, the sulfate ion concentration in the lithium-containing mother solution may be 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L or 105 g / L, or the sulfate ion concentration in the lithium-containing mother solution may be between any two of the above concentrations.

[0066] In this example, the resource utilization method is used to recycle a specific lithium-containing mother liquor. The cost of the raw materials required is relatively low, the recovery efficiency is relatively high, and the residual lithium ions can be recovered more fully, thus having high economic benefits.

[0067] As an example of this embodiment, the lithium-containing mother liquor is selected from the lithium-precipitated mother liquor of waste lithium iron phosphate batteries or the lithium-precipitated mother liquor produced by lithium extraction from lithium ore. As a further example, the lithium-precipitated mother liquor of waste lithium iron phosphate batteries refers to the solution obtained after lithium ions are precipitated and solid-liquid separation is performed in the process of recycling waste lithium iron phosphate batteries. The lithium-precipitated mother liquor produced by lithium extraction from lithium ore refers to the solution obtained after lithium ions are precipitated and solid-liquid separation is performed in the process of lithium extraction from lithium ore. The product of the above-mentioned lithium ion precipitation is usually lithium carbonate. The precipitation of lithium ions in the above-mentioned precipitation process is not complete, so there is still a certain amount of lithium ions in the lithium-precipitated mother liquor. At the same time, the above-mentioned lithium-precipitated mother liquor usually contains more sulfate ions. The resource utilization method of the lithium-containing mother liquor of the present application is applicable to the recovery and utilization of lithium ions in the two lithium-precipitated mother liquors. In some other embodiments, the resource utilization method of the lithium-containing mother liquor of the present application can also be applied to the recovery and utilization of lithium ions using other lithium-containing mother liquors containing similar components as raw materials.

[0068] Step S2, mixing the lithium-containing mother liquor with the phosphate solution and then performing lithium precipitation treatment to obtain a lithium-containing slurry.

[0069] In this embodiment, the ratio of the amount of lithium ions in the lithium-containing mother solution to the amount of phosphate ions in the phosphate solution is 3:(0.7~0.8). Optionally, the ratio of the amount of lithium ions in the lithium-containing mother solution to the amount of phosphate ions in the phosphate solution can be 3:0.7, 3:0.72, 3:0.74, 3:0.76, 3:0.78, 3:0.8. The amount of phosphate ions in this feed ratio is relatively low, which is conducive to better improving the peritectic problem and improving the purity of lithium phosphate in the first solid material while precipitating a large amount of lithium ions. When the amount of phosphate ions is more (for example, the ratio of the amount of lithium ions in the lithium-containing mother solution to the amount of phosphate ions in the phosphate solution is 3:0.9, 3:1, 3:2, etc.), the improvement of the lithium ion recovery rate is extremely limited, which will not only increase the material cost, but also introduce too many phosphate ions into the solution, which is not conducive to the purity of the material obtained in the subsequent concentration and crystallization step. When the amount of phosphate ions used is even smaller (for example, the molar ratio of lithium ions in the lithium-containing mother liquor to phosphate ions in the phosphate solution is 3:0.4, 3:0.5, 3:0.6, etc.), the yield of lithium phosphate solid phase material is low, and the concentration of lithium ions in the lithium-containing slurry is still high, which is not conducive to adsorption in subsequent steps.

[0070] As an example of this embodiment, the step of mixing the lithium-containing mother solution with the phosphate solution may be performed in a reaction vessel.

[0071] As an example of this embodiment, in the step of mixing the lithium-containing mother solution with the phosphate solution, the lithium-containing mother solution is added to the phosphate solution.

[0072] In conventional technology, phosphate solid or phosphate solution is usually directly added to the lithium-containing mother solution. This forward feeding method is easy to cause peritectic formation of lithium phosphate, increase the consumption of phosphate, and have a low lithium ion yield. In this embodiment, the reverse feeding method of adding the lithium-containing mother solution to the phosphate solution is adopted, which is conducive to effectively avoiding the peritectic problem and promoting more sufficient precipitation of lithium ions, thereby further improving the purity of lithium phosphate in the first solid material and the recovery rate of lithium ions.

[0073] As a further example of this embodiment, the lithium-containing mother solution is added to the phosphate solution within 0.5 h to 4 h. It is understood that the lithium-containing mother solution can be added to the phosphate solution in batches or continuously.

[0074] In this embodiment, the lithium-containing mother solution is added to the phosphate solution within 0.5 h to 4 h, which is beneficial for the full crystallization and growth of lithium phosphate and improves the purity of lithium phosphate in the obtained first solid material.

[0075] As an example of this embodiment, the phosphate in the phosphate solution includes one or more of sodium dihydrogen phosphate and disodium hydrogen phosphate. It can be understood that in other embodiments, the phosphate in the phosphate solution can also be other soluble phosphates, such as sodium phosphate.

[0076] In this embodiment, sodium dihydrogen phosphate and disodium hydrogen phosphate have high solubility. Using sodium dihydrogen phosphate and disodium hydrogen phosphate as solutes in the phosphate solution is beneficial to reducing the required volume of the phosphate solution, reducing the dilution of lithium ions during the feeding process, and facilitating the full precipitation of lithium ions; and sodium dihydrogen phosphate and disodium hydrogen phosphate can also produce hydrogen ions, which is beneficial to adjusting the pH value after the lithium precipitation reaction to an appropriate range, reducing or avoiding the use of additional acid-base regulators.

[0077] As an example of this embodiment, the phosphate solution is a saturated solution of phosphate ions.

[0078] In this embodiment, compared with an unsaturated solution, a saturated solution of phosphate ions is used as the phosphate, and lithium ions can combine and precipitate with the phosphate ions more quickly and more fully, which is conducive to obtaining a higher lithium ion recovery rate and resource utilization efficiency.

[0079] As an example of this embodiment, before mixing the lithium-containing mother liquor with the phosphate solution, the lithium-containing mother liquor is heated to 80°C~100°C, preferably 90°C~95°C. For example, the lithium-containing mother liquor can be heated to 85°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, or the lithium-containing mother liquor can be heated to any two temperatures above. Heating the lithium-containing mother liquor to 80°C~100°C, preferably 90°C~95°C is more conducive to promoting the formation of lithium phosphate precipitation. First heating the lithium-containing mother liquor to 80°C~100°C, preferably 90°C~95°C, is conducive to the lithium ions in the lithium-containing mother liquor to more quickly combine with phosphate ions to form precipitation during lithium precipitation treatment, which is conducive to improving production efficiency and lithium ion recovery rate.

[0080] As a further example of this embodiment, in order to fully precipitate lithium ions, it is usually necessary to perform lithium precipitation treatment at a temperature of 80°C to 100°C, preferably 90°C to 95°C. Therefore, before mixing the lithium-containing mother solution with the phosphate solution, heating the lithium-containing mother solution to 90°C to 95°C is beneficial to saving the heating time during the lithium precipitation process, thereby improving production efficiency.

[0081] As an example of this embodiment, during the lithium precipitation treatment, the temperature of the lithium precipitation treatment is 80°C to 100°C, preferably 90°C to 95°C, and the holding time of the lithium precipitation treatment is 2h to 4h. For example, the temperature of the lithium precipitation treatment is 85°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, or the temperature of the lithium precipitation treatment may be between any two of the above temperatures. For another example, the holding time of the lithium precipitation treatment is 2h, 2.5h, 3h, 3.5h, 4h, or the holding time of the lithium precipitation treatment may be between any two of the above temperatures.

[0082] In this embodiment, the lithium-containing mother solution is heated to 80°C to 100°C, preferably 90°C to 95°C, and the temperature of the lithium precipitation treatment is controlled to 80°C to 100°C, preferably 90°C to 95°C, which is conducive to the rapid and sufficient precipitation of lithium ions and phosphate ions in the lithium-containing mother solution, and is conducive to improving the efficiency of resource utilization and the recovery rate of lithium ions. Controlling the holding time to within 2h to 4h is conducive to the full crystallization and crystal growth of lithium phosphate, and is conducive to further improving the purity of lithium phosphate in the obtained first solid material.

[0083] After the reaction process in step S2, the main component of the solid phase component in the formed lithium-containing slurry is lithium phosphate precipitate, and the liquid phase component contains residual lithium ions and sulfate ions.

[0084] In step S3, the lithium-containing slurry is subjected to solid-liquid separation to obtain a pre-adsorption liquid and a first solid material.

[0085] As an example of this embodiment, the solid-liquid separation process can be performed in a solid-liquid separator. Further, depending on the actual separation method, the solid-liquid separator can include a filter press, a centrifuge, a suction filter or a sedimentation tank. In this embodiment, a plate and frame filter press can be used to achieve separation between the pre-adsorption liquid and the first solid material.

[0086] As an example of this embodiment, the solid-liquid separation treatment method is filtration, such as filter pressing or suction filtration. In other embodiments, the solid-liquid separation treatment method can also be centrifugation or static precipitation. The solid phase material obtained after the solid-liquid separation treatment is used as the first solid material, and the liquid phase material obtained is used as the pre-adsorption liquid, and the pre-adsorption liquid contains residual lithium ions and sulfate ions.

[0087] As an example of this embodiment, the lithium ion concentration in the pre-adsorption solution is 200ppm to 500ppm. For example, the lithium ion concentration in the pre-adsorption solution may be 200ppm, 250ppm, 300ppm, 350ppm, 400ppm, 450ppm, 500ppm, or the lithium ion concentration in the pre-adsorption solution may be between any two of the above concentrations.

[0088] In this embodiment, the lithium ion concentration in the pre-adsorption liquid is controlled to be 200ppm~500ppm and the lithium ion concentration in the adsorption tail liquid is less than 20ppm, which is conducive to the adsorbent fully adsorbing lithium ions and controlling the loss of the adsorbent, thereby reducing the use cost of the adsorbent.

[0089] As an example of this embodiment, the pH value of the pre-adsorption liquid is 9.5-10.5.

[0090] Titanium-based adsorbents have a dissolution problem when in contact with a solution with a pH value greater than 11.5. In this embodiment, a pre-adsorption solution with a pH value of 9.5 to 10.5 is used to provide sufficient alkalinity for the adsorption of lithium ions by the adsorbent so that the lithium ions are fully adsorbed, which is beneficial to avoid the dissolution problem of the adsorbent during the adsorption process and increase the service life of the adsorbent.

[0091] It can be understood that when sodium dihydrogen phosphate or disodium hydrogen phosphate is used as the phosphate, a small amount of hydrogen ions can be introduced into the lithium-containing slurry, so that the pH value of the pre-adsorption liquid obtained after solid-liquid separation is 9.5-10.5, and no additional pH regulator is required to avoid dilution of the lithium ion concentration in the lithium-containing slurry. If other phosphate salts (such as sodium phosphate) are used, the pH value in the lithium-containing slurry is high, and an additional pH adjustment process is required, such as adding a pH regulator (such as phosphoric acid, sulfuric acid, etc.) to the lithium-containing slurry, which will also lead to a decrease in the lithium ion concentration.

[0092] As an example of this embodiment, after the solid-liquid separation treatment, the method further includes a step of washing the first solid material with a washing liquid. The washing liquid may be at least one of pure water, distilled water, ultrapure water, and deionized water. Further, in the step of washing the first solid material with the washing liquid, the first solid material may be washed once or multiple times (e.g., twice, three times, four times, five times, etc.), and the volume of the washing liquid used in each washing is more than twice the volume of the first solid material, so as to remove soluble impurity ions in the first solid material.

[0093] As an example of this embodiment, after the first solid material is washed with a washing liquid, a step of drying the washed first solid material (eg, drying) is further included to remove moisture from the washed first solid material.

[0094] In this example, the first solid material obtained by washing with a washing liquid removes the impurity ions remaining on the surface of the lithium phosphate, further improving the purity of the lithium phosphate in the first solid material. After experimental verification, the purity (in terms of mass fraction) of the lithium phosphate material obtained by the first solid material obtained by the lithium precipitation treatment of the present application is more than 95% after being washed with a washing liquid and dried, reaching the industrial-grade lithium phosphate standard. That is, after washing and drying, the first solid material can be directly sold or returned to the production line to increase the lithium concentration of the leachate. For example, for the battery black powder lithium extraction production line, lithium phosphate can be returned to the lithium leaching process section of the battery powder recovery production line to increase the lithium concentration in the leachate. For the lithium ore extraction production line, lithium phosphate can be returned to the phosphoric acid roasting process section to increase the lithium concentration in the leachate.

[0095] As a further example of this embodiment, after the first solid material is washed with pure water and dried, the purity (by mass fraction) of the lithium phosphate is above 95%. For example, the purity of the lithium phosphate may be 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, or the purity of the lithium phosphate may be between any two of the above purities.

[0096] Step S4, using an adsorbent to adsorb lithium ions in the adsorption front liquid to obtain an adsorption tail liquid.

[0097] It is understood that the adsorbent should be selected from an adsorbent capable of adsorbing lithium ions from a solution. As an example of this embodiment, the adsorbent includes a titanium-based adsorbent. Compared with aluminum-based adsorbents that are not suitable for alkaline solutions and manganese-based adsorbents that are not suitable for solutions containing sulfate ions, the use of titanium-based adsorbents has a relatively long service life and can ensure sufficient adsorption of lithium ions.

[0098] As an example of this embodiment, the titanium-based adsorbent is selected from at least one of the following products: Anhui Yuxiang UL-6, Tefeng New Materials G-100, Tefeng New Materials G-200, Jiuwu High-Tech JW-LTOS, Haipu HP180 and Haipu HPL900.

[0099] As an example of this embodiment, the adsorbent may be disposed in a fixed bed or a continuous moving bed adsorption device so that the pre-adsorption liquid flows through the adsorbent, thereby facilitating the adsorbent to adsorb lithium ions in the pre-adsorption liquid.

[0100] As a further example of this embodiment, in the step of adsorbing lithium ions in the pre-adsorption solution, the adsorption time can be controlled to be 3 hours to 10 hours. For example, the adsorption time can be controlled to be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or the adsorption time can be controlled to be between any two of the above times.

[0101] In this example, controlling the adsorption time is beneficial to allow the adsorbent to fully adsorb the lithium ions in the pre-adsorption solution.

[0102] It can be understood that in the process of using an adsorbent to adsorb lithium ions in the pre-adsorption liquid, the flow rate of the pre-adsorption liquid can be adjusted according to the lithium ion concentration in the pre-adsorption liquid to take into account both the lithium ion recovery rate and the adsorption efficiency.

[0103] In this embodiment, most of the lithium ions in the lithium-containing mother liquor are recovered by sequentially adopting lithium precipitation treatment and adsorbent adsorption, which is not only beneficial to the full recovery of lithium ions, but also beneficial to obtaining by-products with higher purity.

[0104] As an example of this embodiment, the lithium ion concentration in the adsorption tail liquid is less than 20 ppm.

[0105] As an example of this embodiment, after the adsorbent is used to adsorb lithium ions in the pre-adsorption liquid, the method further includes: using an acid solution to desorb the adsorbent.

[0106] In this embodiment, the adsorbent is desorbed by an acid solution to form a lithium solution enriched with lithium ions, which is conducive to further recycling of lithium elements. The lithium solution can be put into a lithium carbonate production line, or the lithium solution can be put into an evaporator for concentration to obtain a lithium-containing solid.

[0107] As a further example of this embodiment, in the process of using acid to desorb the adsorbent, the acid used is a strong acid. Preferably, the acid is selected from one or more of dilute sulfuric acid and dilute hydrochloric acid. Dilute sulfuric acid and dilute hydrochloric acid are strong in acidity and are not strong oxidizing acids, which is conducive to maintaining the service life of the adsorbent.

[0108] As a further example of this embodiment, the pH value of the acid solution used is 1.5 to 1.8. For example, the pH value of the acid solution used is 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, or the pH value of the acid solution used can also be between any two of the above pH values. The use of the acid solution in this pH range can ensure sufficient desorption of lithium ions.

[0109] As a further example of this embodiment, during the desorption process, the temperature of the acid solution used is 40° C. to 50° C. For example, the temperature of the acid solution used is 40° C., 42° C., 44° C., 45° C., 46° C., 48° C., 50° C., or the temperature of the acid solution used may be between any two of the above temperatures.

[0110] Step S5, concentrating and crystallizing the adsorption tail liquid to obtain a second solid material.

[0111] It can be understood that after the pre-adsorption liquid is adsorbed by the adsorbent, the adsorption tail liquid is formed, the lithium ions in the adsorption tail liquid are basically removed, and the main components of the adsorption tail liquid are cations and sulfate ions in the phosphate solution. Therefore, the main component of the second solid material formed by the adsorption tail liquid after the concentration and crystallization treatment is sulfate. In this embodiment, the main components of the adsorption tail liquid are sodium ions and sulfate ions. When the adsorption tail liquid is concentrated and crystallized, the main component of the second solid material formed is sodium sulfate, that is, glauber salt.

[0112] As an example of this embodiment, before the adsorption tail liquid is subjected to concentration and crystallization treatment, the process further includes: adjusting the pH value of the adsorption tail liquid to 5.0-6.0.

[0113] In this embodiment, adjusting the pH value of the adsorption tail liquid is beneficial to improving the purity of the sodium sulfate in the second solid material.

[0114] As a further example of this embodiment, sulfuric acid can be used to adjust the pH value of the adsorption tail liquid. Using sulfuric acid to adjust the pH value of the adsorption tail liquid can avoid the introduction of other impurity ions and is also beneficial to improving the purity of sodium sulfate in the second solid material.

[0115] As an example of this embodiment, the step of concentrating and crystallizing the adsorption tail liquid includes: sequentially performing evaporation and concentration treatment and freezing and crystallization treatment on the adsorption tail liquid to obtain a second solid material and a crystallization residual liquid; the second solid material is subjected to drying treatment (e.g., heat drying treatment, etc.) to obtain glauber salt. During the evaporation and concentration treatment, the adsorption tail liquid can be evaporated until crystals are about to precipitate, and then the adsorption tail liquid is subjected to freezing and crystallization treatment.

[0116] The evaporation concentration treatment and the freezing crystallization treatment performed in sequence are beneficial to improving the recovery rate of sodium sulfate. During the evaporation concentration treatment, the adsorption tail liquid can be evaporated until crystals are about to precipitate, and then the adsorption tail liquid is subjected to freezing crystallization treatment.

[0117] As an example of this embodiment, the step of performing evaporation and concentration treatment on the adsorption tail liquid can be performed in an evaporator, and the step of performing cooling and crystallization treatment on the adsorption tail liquid can be performed in a cooling crystallizer.

[0118] As an example of this embodiment, the purity (by mass fraction) of sodium sulfate in the obtained glauber salt is above 99%.

[0119] As an example of this embodiment, the content of lithium ions in the obtained sodium sulphate (in terms of mass concentration) is lower than 50 ppm.

[0120] As a further example of this embodiment, the method further includes: preparing the crystallization residual solution into a phosphate solution, and recycling the solution to mix the lithium-containing mother liquor with the phosphate solution.

[0121] In this embodiment, the lithium ions and sulfate ions in the crystallization residual liquid have been basically removed, so mainly a small amount of phosphate ions remain in the crystallization residual liquid. Reusing them in the phosphate solution will not affect the recovery rate of lithium ions and sulfate ions, but will also help to fully utilize the phosphate ions and save the cost of resource utilization.

[0122] As a further example of this embodiment, in the process of preparing the crystallization residual solution into a phosphate solution, phosphate can be added to the crystallization residual solution to prepare a saturated solution of phosphate ions.

[0123] As a further example of this embodiment, in the process of preparing the crystallization residual solution into a phosphate solution, phosphate and phosphoric acid can be added to the crystallization residual solution to prepare a saturated solution of sodium dihydrogen phosphate and / or disodium hydrogen phosphate.

[0124] It can be understood that through the above steps S1 to S5, the resource utilization method of the lithium-containing mother solution of the present application can be completed.

[0125] After experimental verification, the resource utilization method of the lithium-containing mother solution of this embodiment first uses a phosphate solution to recover the lithium element in the lithium-containing mother solution for the first time. About 80% of the lithium can be recovered during the first recovery process, and then an adsorbent is used to recover the small amount of lithium remaining in the liquid before adsorption of about 20%. The two recovery processes can achieve a lithium element recovery rate of more than 99% in the lithium-containing mother solution, and fully recover the lithium element. Among them, the initial recovery and utilization of a lower cost to achieve the recovery of most of the lithium elements, combined with the secondary recovery of higher costs to achieve the full recovery of the remaining lithium elements. Compared with the method of single recovery using a phosphate solution or a single recovery using an adsorbent, the method of single recovery using a phosphate solution has a low yield and the problem that the low-concentration lithium element in the remaining liquid is difficult to recover. The method of single recovery using an adsorbent has different systems. The system is different, the adsorption rate of the lithium element is low, and the adsorbent is large and the cost is high. The resource utilization method can achieve full recovery of the lithium element while controlling the recovery cost to be low. Furthermore, since the lithium recovery rate of the resource utilization method of the lithium-containing mother liquor of the present application can reach more than 99%, the lithium impurity content in the adsorption tail liquid is extremely small. The adsorption tail liquid can be further concentrated and crystallized to form a by-product with extremely high purity, thereby generating additional economic benefits.

[0126] Furthermore, the present application also provides a resource utilization device for lithium-containing mother liquor, which includes: a lithium precipitation reactor, a solid-liquid separator, an adsorber, an evaporator and a cooling crystallizer. Among them, the discharge port of the lithium precipitation reactor is connected to the feed port of the solid-liquid separator, the solid discharge port of the solid-liquid separator is connected to the feed port of the material collection container, the liquid discharge port of the solid-liquid separator is connected to the feed port of the adsorber, an adsorbent is provided in the adsorber, the discharge port of the adsorber is connected to the feed port of the evaporator, and the discharge port of the evaporator is connected to the feed port of the cooling crystallizer.

[0127] The resource utilization device of the lithium-containing mother solution is used to implement the resource utilization method of the lithium-containing mother solution as described in the above embodiment.

[0128] The lithium precipitation reactor is used as a container for lithium precipitation after the lithium-containing mother liquor is mixed with the phosphate solution. The solid-liquid separator is used to perform solid-liquid separation on the lithium-containing slurry formed after the lithium precipitation treatment to obtain a pre-adsorption liquid and a first solid material. The adsorber is used to adsorb lithium ions in the pre-adsorption liquid obtained after the solid-liquid separation treatment and discharge the adsorption tail liquid, the evaporator is used to evaporate and concentrate the adsorption tail liquid discharged from the adsorber, and the cooling crystallizer is used to cool and crystallize the liquid discharged from the evaporator to obtain a second solid material.

[0129] As an example of this embodiment, phosphorus and lithium are enriched and concentrated in the crystallization residual liquid after cooling crystallization. The crystallization residual liquid is mixed with phosphate and water to prepare a phosphate solution and used for lithium precipitation treatment, which is conducive to achieving a high recovery rate of lithium and phosphorus elements and reducing external discharge losses.

[0130] As an example of this embodiment, the lithium precipitation reactor may include a reaction kettle.

[0131] As an example of this embodiment, according to different actual separation methods, the solid-liquid separator may include a filter press, a centrifuge, a suction filter or a sedimentation tank. In this embodiment, a plate and frame filter press may be used to separate the pre-adsorption liquid and the first solid material.

[0132] As an example of this embodiment, the adsorber may include a fixed bed adsorber or a moving bed adsorber. The adsorbent in the adsorber is selected from titanium-based adsorbents.

[0133] The resource utilization system of the lithium-containing mother solution can realize the resource utilization method of the lithium-containing mother solution as described in the above embodiment.

[0134] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0135] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0136] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0137] Example 1

[0138] Use Figure 2 The process flow shown is to utilize lithium-containing mother liquor as a resource, as follows.

[0139] (1) The solution after lithium carbonate precipitation of waste lithium iron phosphate batteries (i.e., lithium precipitation mother liquor) is used as the lithium-containing mother liquor, wherein the lithium concentration is 1600ppm±150ppm and the sulfate ion concentration is 80g / L.

[0140] (2) Control the temperature of the lithium-containing mother liquor to 92°C, and gradually add the lithium-containing mother liquor to the prepared phosphate solution within 2 hours. The phosphate solution is saturated sodium dihydrogen phosphate (NaH 2 PO 4 ) solution, the ratio of the amount of lithium in the lithium-containing mother liquor to the amount of phosphate ion in the phosphate solution is 3:0.75. After the feeding is completed, the temperature is kept warm for 3 hours. During the feeding process and the insulation process, the overall temperature of the mixed solution is maintained at 92°C to allow the lithium phosphate to be fully precipitated. After the reaction, a lithium-containing slurry is obtained.

[0141] (3) filtering to separate the solid phase component and the liquid phase component in the lithium-containing slurry, with the solid phase component serving as the first solid material and the liquid phase component serving as the pre-adsorption liquid; washing the first solid material with pure water, with the volume ratio of pure water to the first solid material being 3:1, repeating the washing three times, and then drying the first solid material to obtain a lithium phosphate product.

[0142] (4) The pre-adsorption liquid obtained in step (3) is put into a fixed bed adsorption equipment filled with a titanium-based adsorbent (Anhui Yuxiang UL-6) to adsorb lithium ions. The lithium concentration of the pre-adsorption liquid is 450ppm±50ppm. The flow rate of the pre-adsorption liquid is controlled so that the adsorption time of the pre-adsorption liquid through the titanium-based adsorbent is 8h. The outflowing liquid is collected as the adsorption tail liquid. The concentration of lithium ions in the adsorption tail liquid is less than 20ppm. The titanium-based adsorbent is analyzed using dilute sulfuric acid with a pH value of 1.6 and a temperature of 45°C to obtain a lithium solution.

[0143] (5) The pH value of the adsorption tail liquid obtained in step (4) is adjusted to 5.5, and then evaporated and concentrated. When crystals are about to precipitate, freeze crystallization is performed, and the obtained crystals are dried to obtain a glauber salt product.

[0144] Example 2

[0145] The only difference between Example 2 and Example 1 is that in step (1), the solution after lithium carbonate precipitation produced by lithium extraction from lithium ore (i.e., lithium precipitation mother liquor) is used as the lithium-containing mother liquor, wherein the lithium concentration is 2200ppm±200ppm and the sulfate ion concentration is 95g / L.

[0146] Example 3

[0147] The only difference between Example 3 and Example 1 is that in step (1), the solution after lithium carbonate precipitation produced by lithium extraction from lithium ore (i.e., lithium precipitation mother liquor) is used as the lithium-containing mother liquor, wherein the lithium concentration is 1800ppm±150ppm and the sulfate ion concentration is 88g / L.

[0148] Example 4

[0149] The only difference between Example 4 and Example 1 is that in step (1), the solution after lithium carbonate precipitation produced by lithium extraction from lithium ore (i.e., lithium precipitation mother liquor) is used as the lithium-containing mother liquor, wherein the lithium concentration is 2500ppm±200ppm and the sulfate ion concentration is 105g / L.

[0150] Example 5

[0151] The only difference between Example 5 and Example 1 is that in step (2), the ratio of the amount of lithium in the lithium-containing mother solution to the amount of phosphate ions in the phosphate solution is 3:0.7.

[0152] Example 6

[0153] The only difference between Example 6 and Example 1 is that in step (2), the ratio of the amount of lithium in the lithium-containing mother solution to the amount of phosphate ion in the phosphate solution is 3:0.8.

[0154] Example 7

[0155] The only difference between Example 7 and Example 1 is that in step (2), the temperature of the lithium-containing mother solution is controlled to be 95° C., and the overall temperature of the mixed solution is maintained at 95° C. during the feeding process and the heat preservation process.

[0156] Example 8

[0157] The only difference between Example 8 and Example 1 is that in step (2), the temperature of the lithium-containing mother solution is controlled to be 90° C., and the overall temperature of the mixed solution is maintained at 90° C. during the feeding process and the heat preservation process.

[0158] Example 9

[0159] The difference between Example 9 and Example 1 is that in step (2), the phosphate solution is saturated disodium hydrogen phosphate (Na 2 HPO 4 ) solution.

[0160] Example 10

[0161] The only difference between Example 10 and Example 1 is that in step (2), the prepared phosphate solution is gradually added to the lithium-containing mother liquor within 2 hours.

[0162] Embodiment 11

[0163] The only difference between Example 11 and Example 1 is that in step (2), the lithium-containing mother solution is gradually added to the prepared phosphate solution within 0.1 h.

[0164] Example 12

[0165] The only difference between Example 12 and Example 1 is that in step (2), the lithium-containing mother liquor is gradually added to the prepared phosphate solution within 0.5 h.

[0166] Embodiment 13

[0167] The only difference between Example 13 and Example 1 is that in step (2), the lithium-containing mother solution is gradually added to the prepared phosphate solution within 4 hours.

[0168] Embodiment 14

[0169] The only difference between Example 14 and Example 1 is that in step (2), the temperature is kept warm for 1.5 hours after the feeding is completed.

[0170] Embodiment 15

[0171] The only difference between Example 15 and Example 1 is that in step (4), the titanium-based adsorbent is analyzed using dilute sulfuric acid at a pH of 1.8 and a temperature of 50°C.

[0172] Example 16

[0173] The only difference between Example 16 and Example 1 is that in step (4), the titanium-based adsorbent is analyzed using dilute sulfuric acid at a pH of 1.5 and a temperature of 40°C.

[0174] Embodiment 17

[0175] The only difference between Example 17 and Example 1 is that in step (4), the flow rate of the pre-adsorption liquid is controlled so that the adsorption time of the pre-adsorption liquid passing through the titanium-based adsorbent is 10 hours.

[0176] Embodiment 18

[0177] The only difference between Example 18 and Example 1 is that in step (4), the flow rate of the pre-adsorption liquid is controlled so that the adsorption time of the pre-adsorption liquid passing through the titanium-based adsorbent is 3 hours.

[0178] Comparative Example 1

[0179] (1) The solution obtained after lithium carbonate precipitation from waste lithium iron phosphate batteries (i.e., lithium precipitation mother liquor) is used as the lithium-containing mother liquor, wherein the lithium concentration is 1600ppm±200ppm.

[0180] (2) The lithium-containing mother liquor in step (1) is added to a fixed bed adsorption device filled with a titanium-based adsorbent to adsorb lithium ions, the flow rate of the pre-adsorption liquid is controlled so that the adsorption time of the pre-adsorption liquid through the titanium-based adsorbent is 8 hours, and the outflowing liquid is collected as the adsorption tail liquid. The pH value of the adsorption tail liquid is 6.5, and the concentration of lithium ions in the adsorption tail liquid is 160ppm±50ppm; the titanium-based adsorbent is analyzed using dilute sulfuric acid with a pH value of 1.6 and a temperature of 45°C to obtain a lithium solution.

[0181] Comparative Example 2

[0182] The difference between this comparative example and Example 1 is:

[0183] (2) The temperature of the lithium-containing mother liquor is controlled at 92° C. Sodium phosphate solid is gradually added to the lithium-containing mother liquor within 2 hours. The ratio of the amount of lithium in the lithium-containing mother liquor to the amount of phosphate ion in the sodium phosphate solid is 3:0.75. After the addition is completed, the mixture is kept warm for 3 hours. During the addition and insulation processes, the overall temperature of the mixed solution is maintained at 92° C. to allow the lithium phosphate to be fully precipitated. After the reaction, a lithium-containing slurry is obtained.

[0184] Comparative Example 3

[0185] The difference between Comparative Example 3 and Comparative Example 2 is that in (2), sodium dihydrogen phosphate solid is gradually added to the lithium-containing mother liquor within 2 hours.

[0186] Comparative Example 4

[0187] The difference between Comparative Example 4 and Example 1 is that:

[0188] In (2), the ratio of the amount of lithium in the lithium-containing mother solution to the amount of phosphate ions in the phosphate solution is 3:1.1.

[0189] Comparative Example 5

[0190] The difference between Comparative Example 5 and Example 1 is that:

[0191] In (2), the ratio of the amount of lithium in the lithium-containing mother solution to the amount of phosphate ions in the phosphate solution is 3:0.6.

[0192] Performance Testing

[0193] 1. The content of lithium phosphate and the content of each impurity element in the lithium phosphate products prepared in step (3) of the above embodiments 1 to 18 and comparative examples 2 to 5 were tested by inductively coupled plasma mass spectrometry (ICP-MS). The results are shown in Table 1.

[0194] 2. Inductively coupled plasma mass spectrometry was used to test the contents of various elements in the lithium solutions obtained in step (4) of the above Examples 1 to 18 and the lithium solutions prepared in Comparative Examples 1 and 4 to 5. The results are shown in Table 2.

[0195] 3. The sodium sulfate content and the content of each impurity element in the glauber salt obtained in step (5) of the above Examples 1 to 18 and the glauber salt prepared in Comparative Examples 4 and 5 were tested by inductively coupled plasma mass spectrometry. The results are shown in Table 3.

[0196] Table 1

[0197]

[0198] From the results in Table 1, it can be seen that the mass fraction of lithium phosphate in the lithium phosphate products obtained in Examples 1 to 18 is relatively high, all of which are above 95%. The mass fractions of Ca, Mg, Cl, Si, Zn, Na and SO 4 2- The contents of impurities such as iodine and iodine are all low, indicating that the resource utilization method of lithium-containing mother liquor provided in the present application achieves the recovery of more than 99% of lithium ions in lithium-containing mother liquor by first mixing the lithium-containing mother liquor with a phosphate solution and then performing lithium precipitation treatment, controlling the feed ratio of lithium ions to phosphate ions to be 3: (0.7-0.8) during mixing, and then using a titanium-based adsorbent to adsorb lithium ions in the pre-adsorption solution.

[0199] In Comparative Example 1, a titanium-based adsorbent is used to directly recover the lithium-containing mother liquor. The lithium-containing mother liquor has a high lithium concentration. The titanium-based adsorbent is directly used to adsorb the lithium-containing mother liquor. The adsorption process of the titanium-based adsorbent is a process in which hydrogen ions in titanate molecules are replaced by lithium ions, which requires consumption of the alkalinity in the solution. Since the alkalinity in the lithium-containing mother liquor is limited and is insufficient to provide the alkalinity required for the adsorption of lithium ions by the adsorbent, when the alkalinity in the adsorption tail liquid is insufficient, the lithium ions cannot be adsorbed, and there is still a large amount of lithium that cannot be adsorbed and recovered. The lithium recovery rate is about 90%. In addition, the titanium-based adsorbent is expensive, and the amount of adsorbent used for direct adsorption will increase by more than 5 times, and the equipment scale will also increase by 5 times. The equipment investment is high, and the cost of resource utilization of the lithium-containing mother liquor is high, reaching RMB 30,000 / t of lithium carbonate.

[0200] Sodium phosphate solid was used to recover lithium phosphate in Comparative Example 2. Sodium phosphate solid was used as a lithium recovery agent. The solubility of sodium phosphate was low, resulting in a serious peritectic phenomenon. Lithium phosphate covered the sodium phosphate, resulting in a low purity of the lithium phosphate product of only 80.7%.

[0201] In Comparative Example 3, sodium dihydrogen phosphate solid was added to the lithium-containing mother liquor, and the generated lithium phosphate solid encapsulated sodium ions in the crystals, and the peritectic phenomenon was also serious. The purity of the obtained lithium phosphate product was low, only 89.7%.

[0202] In Comparative Example 4, the ratio of the amount of lithium element in the lithium-containing mother liquor to the amount of phosphate ion in the phosphate solution is 3:1.1, which has a very limited effect on the improvement of the lithium ion recovery rate. It not only increases the material cost, but also introduces too many phosphate ions into the solution, which is not conducive to the purity of the material obtained in the subsequent concentration and crystallization step.

[0203] In Comparative Example 5, the ratio of the amount of lithium in the lithium-containing mother liquor to the amount of phosphate ions in the phosphate solution is 3:0.6, the yield of the lithium phosphate product is low, and the concentration of lithium ions in the lithium-containing slurry is high, which is not conducive to the sufficient adsorption of lithium ions in the subsequent steps.

[0204] Table 2

[0205]

[0206] Table 3

[0207]

[0208] It can be seen from the results in Table 2 that the method for resource utilization of lithium-containing mother liquor provided in the present application controls the adsorption time to be 3h~10h by adsorbing lithium ions in the pre-adsorption liquid and desorbing the adsorbent with acid solution, the pH value of the acid solution used for desorption is 1.5~1.8, and the temperature of the acid solution used for desorption is 40℃~50℃, thereby obtaining a lithium solution enriched in lithium ions and low in other metal elements, thereby realizing further recovery and utilization of lithium elements.

[0209] It can be seen from the results in Table 3 that the resource utilization method of the lithium-containing mother liquor provided in the present application obtains alum with a purity between 99.13% and 99.57% by concentrating and crystallizing the adsorption tail liquid, thereby achieving full resource utilization of the adsorption tail liquid and generating additional economic benefits.

[0210] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for resource utilization of lithium-containing mother liquor, characterized in that: The steps include: providing a lithium-containing mother solution containing lithium ions and sulfate ions; The lithium-containing mother solution is mixed with a phosphate solution and then subjected to lithium precipitation treatment to obtain a lithium-containing slurry; The lithium-containing slurry is subjected to solid-liquid separation to obtain a pre-adsorption liquid and a first solid material; Adsorbing lithium ions in the pre-adsorption liquid with an adsorbent to obtain an adsorption tail liquid; as well as, The adsorption tail liquid is concentrated and crystallized to obtain a second solid material; The molar ratio of lithium ions in the lithium-containing mother solution to phosphate ions in the phosphate solution is 3:(0.7-0.8).

2. The method for resource utilization of lithium-containing mother solution according to claim 1, characterized in that: In the process of mixing the lithium-containing mother solution with the phosphate solution, adding the lithium-containing mother solution to the phosphate solution; and / or, The lithium-containing mother solution is added to the phosphate solution within 0.5 h to 4 h.

3. The method for resource utilization of lithium-containing mother solution according to claim 2, characterized in that: The phosphate in the phosphate solution includes one or more of sodium dihydrogen phosphate and disodium hydrogen phosphate; and / or, The phosphate solution is a saturated solution of phosphate ions; and / or, After the solid-liquid separation treatment, the method further includes a step of washing the first solid material with a washing liquid.

4. The method for resource utilization of lithium-containing mother solution according to claim 3, characterized in that: Before mixing the lithium-containing mother solution with the phosphate solution, heating the lithium-containing mother solution to 80° C. to 100° C.; and / or, The temperature of the lithium precipitation treatment is 80° C. to 100° C., and the insulation time of the lithium precipitation treatment is 2 h to 4 h.

5. The method for resource utilization of lithium-containing mother solution according to any one of claims 1 to 4, characterized in that: The pH value of the pre-adsorption liquid is 9.5-10.5; and / or, The lithium ion concentration in the pre-adsorption liquid is 200ppm-500ppm, and the lithium ion concentration in the adsorption tail liquid is less than 20ppm.

6. The method for resource utilization of lithium-containing mother solution according to any one of claims 1 to 4, characterized in that: The adsorbent includes a titanium-based adsorbent. After the adsorbent is used to adsorb lithium ions in the pre-adsorption liquid, the method further includes: using an acid solution to desorb the adsorbent.

7. The method for resource utilization of lithium-containing mother solution according to any one of claims 1 to 4, characterized in that: The phosphate solution contains sodium ions. Before the adsorption tail liquid is subjected to concentration and crystallization treatment, the method further includes: adjusting the pH value of the adsorption tail liquid to 5.0-6.0; The step of concentrating and crystallizing the adsorption tail liquid comprises: sequentially performing evaporation concentration treatment and freezing crystallization treatment on the adsorption tail liquid to obtain the second solid material and crystallization residual liquid; The second solid material is dried to obtain glauber salt.

8. The method for resource utilization of lithium-containing mother solution according to claim 7, characterized in that: Also includes: The crystallization residual solution is prepared into a phosphate solution and is reused in the step of mixing the lithium-containing mother solution with the phosphate solution.

9. The method for resource utilization of lithium-containing mother solution according to any one of claims 1 to 4, characterized in that: The lithium ion concentration in the lithium-containing mother solution is 1450ppm to 2700ppm; and / or, The lithium-containing mother liquor is selected from the lithium-precipitated mother liquor of waste lithium iron phosphate batteries or the lithium-precipitated mother liquor produced by extracting lithium from lithium ore.

10. A resource utilization device for lithium-containing mother liquor, characterized in that: include: A lithium precipitation reactor, a solid-liquid separator, an adsorber, an evaporator and a cooling crystallizer; wherein the discharge port of the lithium precipitation reactor is connected to the feed port of the solid-liquid separator, the discharge port of the solid-liquid separator is connected to the feed port of the adsorber, an adsorbent is arranged in the adsorber, the discharge port of the adsorber is connected to the feed port of the evaporator, and the discharge port of the evaporator is connected to the feed port of the cooling crystallizer.

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