Method for recovering lithium from lithium-containing aluminum electrolysis waste slag

Abstract

The present invention relates to the field of lithium extraction, and specifically discloses a method for recovering lithium from lithium-containing aluminum electrolytic waste slag, wherein the aluminum electrolytic waste slag containing lithium is pretreated in a pretreatment liquid to obtain pretreatment slag, wherein the pretreatment liquid contains HF; the pretreatment slag is mixed with an alkaline substance for alkaline leaching to obtain a lithium extraction solution; the lithium extraction solution is mixed with a water-soluble carbonate for impurity removal treatment to remove calcium and magnesium impurities therein, and the impurity-removing lithium liquid is separated; the impurity-removing lithium liquid and an organic phase A containing formula 1 are mixed for a first phase separation to obtain a lithium-carrying organic phase, and then the lithium-carrying organic phase and an aqueous phase B are subjected to a second phase separation to obtain a lithium-carrying aqueous phase; the aqueous phase B is an aqueous solution dissolved with phosphoric acid and / or sulfonic acid. The present invention has shown that the combination of the pretreatment-first phase separation and the second phase separation process can unexpectedly achieve synergy, and can solve the problem that lithium is difficult to extract, recover and extract due to the physical and chemical characteristics of lithium-containing aluminum electrolytic slag.

Description

Technical Field

[0001] The invention belongs to the field of valuable metal recovery, and in particular relates to the field of lithium recovery from lithium-containing waste residues. Background Art

[0002] With the rapid development of my country's aluminum electrolysis industry and the increasing demand for aluminum products, a large amount of medium and low-grade lithium-containing bauxite is mined and used to prepare metallurgical-grade alumina. Lithium-containing alumina is continuously transported to the electrolyte system during the production process. Once lithium enters the electrolyte system, it will be very stable and difficult to precipitate. The lithium content will accumulate with the continuous operation of the aluminum electrolytic cell, and eventually form a lithium-rich aluminum electrolyte. The lithium fluoride content of some companies' aluminum electrolytic cells is as high as 5-7.0wt%. Aluminum electrolyte is the core part of the aluminum electrolysis production process. In contrast, lithium-rich aluminum electrolyte will lead to lower production temperature, lower alumina solubility, more precipitation at the bottom of the electrolytic cell, and poor stability of the aluminum electrolytic cell. These waste aluminum electrolytes are mainly treated by stacking or landfilling. The stacked waste electrolyte not only occupies the functional space of aluminum enterprises, but the soluble fluorine may also leak into the ground with rainwater, causing environmental pollution. At the same time, it also leads to the waste of many lithium resources in lithium-containing aluminum electrolytes.

[0003] Lithium resources are essential energy materials and strategic resources. With the rapid development of new energy industries, lithium demand has exploded, and the demand for lithium resources has become increasingly severe. Compared with traditional lithium resources, aluminum electrolyte can also be considered non-traditional. The clean and efficient recycling of lithium, aluminum and fluorine not only helps to achieve the recycling of fluorides and solve environmental problems in the aluminum electrolysis industry, but also helps to alleviate the pressure brought by the rapid development of lithium resources.

[0004] The prior art also reports some methods for recovering lithium from aluminum electrolytic slag. For example, a Chinese patent document with publication number CN116334411A discloses a method for recovering lithium from aluminum electrolyte slag by low-temperature multi-stage leaching. Another example is a Chinese patent document with publication number CN117089721A, which discloses a method for recovering lithium from aluminum electrolyte. Specifically, the aluminum electrolyte is mixed with auxiliary materials for leaching, wherein the auxiliary materials are calcium oxide and calcium hydroxide, and then the leaching solution is removed by extraction. The lithium leaching rate of this technical solution is 80-85%.

[0005] Although the prior art has reported some processes for recovering lithium from aluminum electrolytic slag, and also reported some extraction processes for improving lithium recovery and purity, the composition of aluminum electrolytic slag is complex, and there are relatively many components such as Si, Ca, Mg, and F, which are easy to form colloids during the treatment process and also easy to poison the extraction system, thereby greatly affecting the extraction recovery rate and selectivity of lithium, and it is difficult to realize the extraction recovery of lithium from aluminum electrolytic slag based on the extraction process. Summary of the invention

[0006] In view of the problems faced in the recovery of lithium from existing lithium-containing aluminum electrolytic waste slag, the purpose of the present invention is to provide a method for recovering lithium from lithium-containing aluminum electrolytic waste slag, aiming to improve the extraction efficiency and selectivity of lithium.

[0007] The lithium-containing electrolytic slag contains a large amount of impurities such as Al, F, and Si. These impurities are easily colloided during the treatment process and easily lead to poisoning of the extractant, which in turn leads to low extraction recovery rate and recovery selectivity of lithium in the aluminum electrolytic slag. In view of the difficulties faced in extracting lithium from lithium-containing aluminum electrolytic waste slag, the present invention has been studied in depth and provides the following solutions:

[0008] A method for recovering lithium from lithium-containing aluminum electrolytic waste slag, comprising pretreating the lithium-containing aluminum electrolytic waste slag in a pretreatment liquid to obtain pretreatment slag, wherein the pretreatment liquid contains HF;

[0009] The pre-treated slag and alkaline substances are mixed to perform alkaline leaching treatment to obtain a lithium extraction solution;

[0010] The lithium extract and the water-soluble carbonate are mixed to perform impurity removal treatment to remove calcium and magnesium impurities therein, and the impurity-removed lithium solution is separated;

[0011] The impurity-removing lithium solution and the organic phase A containing Formula 1 are mixed to perform a first phase separation to obtain a lithium-carrying organic phase, and then the lithium-carrying organic phase and the aqueous phase B are subjected to a second phase separation to obtain a lithium-carrying aqueous phase;

[0012]

[0013] The M is H, Na, K or NH4, and the R is C4 to C 12 The alkyl group;

[0014] The aqueous phase B is an aqueous solution containing phosphoric acid and / or sulfonic acid.

[0015] In view of the problem that the extraction recovery rate and recovery selectivity of lithium in lithium-containing aluminum electrolytic waste slag are not ideal due to its special structure and phase characteristics, the present invention provides a new solution, which uses a pretreatment liquid for preliminary treatment, and then cooperates with alkali extraction, the first phase separation involving formula 1, and the second phase separation involving phosphoric acid and / or sulfonic acid. This innovative solution can unexpectedly achieve a synergistic effect, thereby significantly improving the recovery rate and recovery selectivity of lithium. The implementation of this technology will provide a more efficient and environmentally friendly solution for the treatment of lithium-containing aluminum electrolytic waste slag, and also provide strong technical support for the development of related industries.

[0016] In the present invention, the lithium-containing aluminum electrolysis waste slag can be any lithium-containing material separated from the aluminum electrolysis process system in the industry. For example, the lithium-containing aluminum electrolysis waste slag contains 2-3wt.% Li, 10-15wt.% Si, 10-15wt.% Al, 30-40wt.% F, 2-5wt.% Mg, and 3-5wt.% Ca.

[0017] In the present invention, in the pretreatment solution, the concentration of HF is 1 to 3 M;

[0018] Preferably, during the pretreatment process, the liquid-to-solid ratio of the lithium-containing aluminum electrolytic waste slag to the pretreatment liquid is above 5 ml / g, and can further be 10 to 40 ml / g;

[0019] In the present invention, the temperature of the pretreatment process is not particularly required, for example, it can be 20 to 90°C, preferably 40 to 95°C, and further 60 to 85°C;

[0020] In the present invention, the time of the pretreatment process can be conventionally adjusted according to the characteristics of the slag, for example, it can be 1 to 4 hours.

[0021] In the present invention, the pre-treated slag is mixed with an aqueous solution containing alkaline substances (ie, alkaline solution) to perform alkaline extraction treatment.

[0022] In the present invention, the alkaline substance includes but is not limited to at least one of sodium hydroxide and potassium hydroxide.

[0023] Preferably, the weight ratio of the pre-treated slag to the alkaline substance is 1:0.5-3; more preferably 1:1-1.5.

[0024] In the present invention, there is no particular requirement for the concentration of the solute in the alkali solution, for example, it can be 1 to 3 M. In the present invention, during the alkali leaching process, the liquid-to-solid ratio of the lithium-containing aluminum electrolytic waste slag to the alkali solution is above 5 ml / g, and can further be 10 to 40 ml / g.

[0025] In the present invention, there is no particular requirement for the temperature during the alkali leaching process, for example, it can be above 20°C, further can be 40 to 95°C, and further can be 60 to 85°C;

[0026] In the present invention, the alkali leaching time is 1 to 4 hours.

[0027] Preferably, cryolite in an amount equivalent to 1-5 wt% of the mass of the aluminum electrolysis waste slag is added during the alkaline leaching process.

[0028] In the present invention, alkaline leaching treatment is carried out with the aid of the cryolite, which helps to further avoid the problem of unsatisfactory lithium extraction effect caused by system colloidization, and also helps to improve the impurity removal effect, solve the extraction poisoning problem, and improve the lithium extraction recovery rate and selectivity.

[0029] In the present invention, water-soluble carbonate is added to the alkaline extract to perform a preliminary Ca / Mg removal treatment.

[0030] In the present invention, the water-soluble carbonate is at least one of sodium carbonate and ammonium carbonate;

[0031] Preferably, the amount of the water-soluble carbonate is 1 to 1.1 times the theoretical amount for completely precipitating Ca / Mg in the lithium extract, and can be further 1 to 1.05 times in consideration of the processing cost;

[0032] In the present invention, the temperature of the impurity removal process is 10-40°C, and considering the requirements of process convenience, it can be further room temperature;

[0033] In the present invention, the time of the impurity removal process is 1 to 3 hours;

[0034] Preferably, during the impurity removal process, a gas is blown into the system, and the gas is at least one of nitrogen and an inert gas. There is no particular requirement for the blowing rate of the gas, for example, it can be 1 to 100 mL / min, and further can be 30 to 70 mL / min.

[0035] In the present invention, under the preferred process, the extraction poisoning problem can be further avoided, and the recovery rate and separation selectivity of lithium can be further improved.

[0036] In the present invention, the pretreatment and impurity removal processes are combined, and further coordinated with the first phase separation treatment involving formula 1 and the second phase separation treatment involving aqueous phase B, which can unexpectedly further synergistically reduce the phase poisoning problem caused by components such as Si and F in the aluminum-containing electrolytic slag, and can further improve the recovery rate and selectivity of lithium.

[0037] In the present invention, the pH of the impurity removal liquid can be controlled, and then mixed with the organic phase A to carry out the first phase separation treatment, and the loaded organic phase, that is, the lithium-loaded organic phase, is collected.

[0038] In the present invention, the pH of the first phase separation stage is 10-13 (ie, the pH of the first phase separation stage).

[0039] In the present invention, in Formula 1, R is C4 to C 12 The alkyl group;

[0040] Preferably, the organic phase containing Formula 1 further contains a hydrophobic diluent, which may be a conventional hydrophobic solvent, for example, at least one of sulfonated kerosene, silicone oil, etc.;

[0041] Preferably, in the first phase separation stage, the volume ratio of the impurity-removing lithium solution to the organic phase containing Formula 1 is 5 to 20:1, and can further be 5 to 10:1;

[0042] In the present invention, the loaded organic phase and the aqueous phase B solution are mixed and then subjected to a second phase separation, thereby, for example, improving the extraction rate and extraction selectivity of lithium.

[0043] In the present invention, in the second phase separation stage, the concentration of the solute in the aqueous phase B is 1 to 5 M;

[0044] Preferably, the pH of the second phase separation stage is 2 to 5;

[0045] Preferably, in the second phase separation stage, the volume ratio of the lithium-carrying organic phase to the phosphoric acid solution is 5 to 20:1, and can further be 5 to 10:1.

[0046] In the present invention, the lithium-carrying aqueous phase is subjected to evaporation and crystallization treatment to obtain lithium dihydrogen phosphate.

[0047] Beneficial Effects

[0048] The present invention innovatively adopts the pretreatment solution for pretreatment, and then combines the alkaline leaching, the first phase separation involving Formula 1 and the second phase separation treatment process involving phosphoric acid, which can unexpectedly achieve synergy and improve the recovery rate and selectivity of lithium.

[0049] In the present invention, cryolite-assisted alkaline extraction treatment and / or gas-assisted impurity removal treatment and sulfonic acid-assisted second-stage phase separation treatment are used, which can solve the problem of unsatisfactory lithium extraction rate and extraction selectivity caused by the physicochemical characteristics of aluminum electrolytic slag, and help to obtain better extraction recovery effect. DETAILED DESCRIPTION

[0050] The present invention will be further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0051] In the present invention, the lithium-containing aluminum electrolytic waste slag contains 2-3wt% Li, 10-15wt% Si, 10-15wt% Al, 30-40wt% F, 2-5wt% Mg, and 3-5wt% Ca.

[0052] In the following cases, as typical examples, unless otherwise stated, the contents of the components are: 2.4wt% Li, 12.3wt% Si, 11.5wt% Al, 35.2wt% F, 4.2wt% Mg, and 3.8wt% Ca.

[0053] In the following cases, the HF solution, sodium hydroxide solution, etc., referred to, are all aqueous solutions unless otherwise stated.

[0054] In the following cases, the room temperature refers to 20-30℃ unless otherwise stated.

[0055] The processes of the first phase separation and the second phase separation can be conventional, and can be single-stage phase separation or multi-stage countercurrent extraction phase separation.

[0056] Embodiment 1:

[0057] Step (1) Pretreatment:

[0058] The lithium-containing waste was pretreated by immersing in 2M HF with a liquid-to-solid ratio of 30 mL / g. After 60 min of treatment, the sample was filtered, washed with water, and air-dried to obtain pretreated slag for later use;

[0059] Step (2) alkali leaching:

[0060] The pretreated slag is mixed with a sodium hydroxide solution, wherein the concentration of the sodium hydroxide solution is 2M and the weight ratio of the sodium hydroxide to the pretreated slag is 1:1, and then the mixture is stirred for alkali leaching at 80°C for 120 minutes, and then filtered to obtain a lithium extract.

[0061] Step (3) removing impurities:

[0062] Sodium carbonate (1.05 times the total molar amount of Ca / Mg precipitates in the lithium extract) was added to the lithium extract, and the mixture was stirred at room temperature for 60 minutes, and then filtered to obtain a lithium solution free of impurities;

[0063] Step (4): First phase separation

[0064] The impurity-removing lithium solution and the organic phase are mixed and subjected to a first phase separation treatment to obtain a lithium-carrying organic phase;

[0065] The organic phase is a sulfonated kerosene mixture containing 10 wt% of Formula 1 (specifically Formula 1-A in this case); the volume ratio of the impurity-removing lithium solution to the organic phase is 8:1; the temperature of the phase separation stage is room temperature, the equilibrium time is 30 minutes, and the pH of the first phase separation stage is 12;

[0066]

[0067] Step (5): Second phase separation

[0068] The lithium-loaded organic phase and 5M phosphoric acid aqueous solution are mixed, and the second phase separation treatment is performed to separate the LiH2PO4 aqueous phase; and then the LiH2PO4 is obtained by crystallization treatment;

[0069] In the second phase separation stage, the volume ratio of the lithium-loaded organic phase to the phosphoric acid aqueous solution was 5:1, the temperature of the phase separation stage was room temperature, the equilibrium time was 30 min, and the pH was 4;

[0070] In the LiH2PO4 product, the total recovery rate of lithium ions is 97.4% and the purity is 97.6%, of which Si and F impurities are 0.22% and 0.25% respectively.

[0071] Example 2

[0072] Compared with Example 1, the only difference is that cryolite is also added to the solution system at the start of alkali leaching in step 2, and its amount is 3% of the weight of the pretreated slag. Other operations and parameters are the same as in Example 1.

[0073] In the LiH2PO4 product, the total recovery rate of lithium ions is 98.5% and the purity is 98.3%, of which Si and F impurities are 0.19% and 0.21% respectively.

[0074] Example 3

[0075] Compared with Example 2, the only difference is that in step 3, during the entire process of impurity removal, nitrogen is bubbled into the solution system at a rate of 60 ml / min.

[0076] In the LiH2PO4 product, the total recovery rate of lithium ions is 98.9%, and the purity of LiH2PO4 is 99.1%, of which Si and F impurities are 0.11% and 0.13% respectively.

[0077] Example 4

[0078] Compared with Example 1, the only difference is that in step 4, Formula 1-B is used to replace Formula 1-A, and other operations and parameters are the same as those in Example 1;

[0079]

[0080] In the LiH2PO4 product, the total recovery rate of lithium ions is 97.1%, and the purity of LiH2PO4 is 97.4%, of which Si and F impurities are 0.30% and 0.28% respectively.

[0081] Example 5

[0082] Compared with Example 1, the only difference is that in step 5, a sulfonic acid aqueous solution of equal concentration is used to replace the phosphoric acid aqueous solution, and the other operations are the same as in Example 1.

[0083] In the lithium product, the total recovery rate of lithium ions is 99.0%, and the purity of the Li product is 99.2%, of which Si and F impurities are 0.12% and 0.10% respectively.

[0084] Compared with Example 1, the use of sulfonic acid in the second phase separation treatment can unexpectedly further improve the lithium recovery effect and selectivity.

[0085] Example 6

[0086] Compared with Example 1, the only difference is that the conditions of steps 1 to 5 are changed, and the difference conditions are:

[0087] Step (1) Pretreatment:

[0088] The concentration of HF is 2.5M, and the liquid-solid ratio is 20mL / g. After 90 minutes of treatment, the sample is filtered, washed with water, and air-dried to obtain the pre-treated slag for later use;

[0089] Step (2) alkali leaching:

[0090] The pretreated slag is mixed with a sodium hydroxide solution, wherein the concentration of the sodium hydroxide solution is 2.5M, and the weight ratio of the sodium hydroxide to the pretreated slag is 1:1.5, and then stirred for alkaline leaching at 60°C for 150 minutes, and then filtered to obtain a lithium extract.

[0091] Step (3) removing impurities:

[0092] Sodium carbonate (1.05 times the total molar amount of Ca / Mg precipitates in the lithium extract) was added to the lithium extract, and the mixture was stirred at room temperature for 90 minutes, and then filtered to obtain a lithium solution free of impurities;

[0093] Step (4): First phase separation

[0094] The impurity-removing lithium solution and the organic phase are mixed and subjected to a first phase separation treatment to obtain a lithium-carrying organic phase;

[0095] The organic phase is sulfonated kerosene containing 15 wt% of Formula 1 (specifically Formula 1-A in this case); the volume ratio of the impurity-removing lithium liquid to the organic phase is 6:1; the temperature of the phase separation stage is room temperature, the time is 40 minutes, and the pH is 12.5;

[0096]

[0097] Step (5): Second phase separation

[0098] The lithium-loaded organic phase and 4M phosphoric acid aqueous solution are mixed and subjected to a second phase separation treatment to separate and obtain a LiH2PO4 aqueous phase; and then subjected to a crystallization treatment to obtain LiH2PO4;

[0099] In the second phase separation stage, the volume ratio of the lithium-loaded organic phase to the phosphoric acid aqueous solution was 6:1, the temperature of the phase separation stage was room temperature, and the time was 40 minutes;

[0100] In the lithium product, the total recovery rate of lithium ions is 97.7%, and the purity of LiH2PO4 is 96.9%, of which Si and F impurities are 0.28% and 0.27% respectively.

[0101] Comparative Example 1

[0102] Compared with Example 1, the only difference is that the pretreatment in step 1 is not performed, but the lithium-containing waste directly replaces the pretreatment slag to perform step 2 and subsequent treatments. Other operations and parameters are the same as in Example 1.

[0103] The recovery rate of lithium ions is 81.3%, the purity of LiH2PO4 is 86.2%, the Si content reaches 3.5% and the F content reaches 1.8%.

[0104] Comparative Example 2

[0105] Compared with Example 1, the only difference is that in step 4, an equal weight of N910 is used to replace Formula 1, and other operations and parameters are the same as in Example 1.

[0106] The recovery rate of lithium ions is 76.8%, the purity of LiH2PO4 is 74.2%, the content of Si impurities reaches 2.3%, and the content of F reaches 1.2%.

[0107] Comparative Example 3

[0108] Compared with Example 1, the only difference is that in step 5, hydrochloric acid is used to replace the phosphoric acid, and other operations and parameters are the same as in Example 1.

[0109] The recovery rate of lithium ions is 85.8%, the purity of LiCl is 88.9%, the content of Si impurities reaches 1.8%, and the content of F reaches 1.3%.

[0110] Comparative Example 4

[0111] Compared with Example 1, the only difference is that in step 5, sulfuric acid is used to replace the phosphoric acid, and other operations and parameters are the same as in Example 1.

[0112] The recovery rate of lithium ions is 74.9%, the purity of Li2SO4 is 73.1%, the content of Si impurities reaches 1.2%, and the content of F reaches 0.9%.

[0113] In summary, through the pretreatment, alkaline extraction, impurity removal, the first phase separation involving formula 1, and the second phase separation treatment with phosphoric acid and / or sulfonic acid parameters, unexpected synergy can be achieved, and the problems of gelation, extraction poisoning, etc. of components such as Si and F in lithium-containing aluminum electrolytic slag can be solved, and the recovery rate and recovery effect of lithium can be synergistically improved.

Claims

1. A method for recovering lithium from lithium-containing aluminum electrolysis waste slag, characterized in that: The aluminum electrolysis waste slag containing lithium is pretreated in a pretreatment liquid to obtain pretreatment slag; the aluminum electrolysis waste slag containing lithium contains 2-3wt.% Li, 10-15wt.% Si, 10-15wt.% Al, 30-40wt.% F, 2-5wt.% Mg, and 3-5wt.% Ca; The pretreatment solution is an HF solution, wherein the concentration of HF is 1-3M; the temperature of the pretreatment process is 20-90°C; the pretreatment time is 1-4 h; The pre-treated slag is mixed with an alkaline solution containing an alkaline substance, and an alkaline extraction treatment is performed to obtain a lithium extraction solution; The alkaline substance includes at least one of sodium hydroxide and potassium hydroxide; The weight ratio of the pre-treated slag to the alkaline substance is 1:0.5-3; The concentration of the solute in the alkali solution is 1~3M; During the alkaline extraction process, the liquid-to-solid ratio of lithium-containing aluminum electrolytic waste slag to alkaline solution is 10~40ml / g; The temperature of the alkali extraction process is 40~95℃; the alkali extraction time is 1~4h; The lithium extract and the water-soluble carbonate are mixed to perform impurity removal treatment to remove calcium and magnesium impurities therein, and the impurity-removed lithium solution is separated; The impurity-removing lithium solution and the organic phase A are mixed for the first phase separation to obtain a lithium-carrying organic phase, and then the lithium-carrying organic phase and the aqueous phase B are subjected to the second phase separation to obtain a lithium-carrying aqueous phase; The organic phase A is a solution composed of Formula 1 and a hydrophobic diluent; the hydrophobic diluent is at least one of sulfonated kerosene and silicone oil; Formula 1 In formula 1, M is H, Na, K or NH4, and R is C4~C 12 The alkyl group; The aqueous phase B is an aqueous solution dissolved with phosphoric acid and / or sulfonic acid; In the first phase separation stage, the volume ratio of the impurity-removing lithium solution to the organic phase containing Formula 1 is 5-20:1; The pH of the first phase separation stage is 10~13.

2. The method for recovering lithium from lithium-containing aluminum electrolytic waste slag according to claim 1, characterized in that: During the pretreatment process, the liquid-to-solid ratio of the lithium-containing aluminum electrolytic waste slag to the pretreatment solution is 20-40 ml / g; The temperature of the pretreatment process is 40~70℃.

3. The method for recovering lithium from lithium-containing aluminum electrolysis waste slag according to claim 1, characterized in that: During the alkaline extraction process, cryolite is added in an amount equivalent to 1-5wt.% of the aluminum electrolysis waste slag.

4. The method for recovering lithium from lithium-containing aluminum electrolysis waste slag according to claim 1, characterized in that: The water-soluble carbonate is at least one of sodium carbonate and ammonium carbonate.

5. The method for recovering lithium from lithium-containing aluminum electrolysis waste slag according to claim 1, characterized in that: The amount of the water-soluble carbonate is 1 to 1.1 times the theoretical amount for completely precipitating Ca / Mg in the lithium extract; The temperature of the impurity removal process is 10~40℃; The time of the impurity removal process is 1~3h.

6. The method for recovering lithium from lithium-containing aluminum electrolysis waste slag according to claim 1 or 5, characterized in that: During the impurity removal process, gas is blown into the system at a blowing rate of 1-100 mL / min, and the gas is at least one of nitrogen and an inert gas.

7. The method for recovering lithium from lithium-containing aluminum electrolytic waste slag according to claim 1, characterized in that: In the second phase separation stage, the concentration of the solute in the aqueous phase B is 1-5 M.

8. The method for recovering lithium from lithium-containing aluminum electrolytic waste slag according to claim 1, characterized in that: The pH of the second phase separation stage is 2-5; In the second phase separation stage, the volume ratio of the lithium-carrying organic phase to the phosphoric acid solution is 5-20:

1.

9. The method for recovering lithium from lithium-containing aluminum electrolytic waste slag according to claim 1, characterized in that: The lithium-carrying aqueous phase is evaporated and crystallized to obtain a product containing lithium dihydrogen phosphate or lithium sulfonate.

Images