A method for efficiently separating lithium and nickel in a nickel-lithium mixed solution based on combined extraction

Abstract

The application discloses a kind of based on combination extraction realizes the efficient separation method of lithium nickel in nickel lithium mixed solution, including respectively determining the concentration of lithium and the concentration of nickel in nickel lithium mixed solution;Adopt the combination extractant formed by extractant A and extractant B, and the volume of both is determined according to specific formula;Then combination extractant is added to nickel lithium mixed solution, and saponification is carried out to obtain aqueous phase lithium liquid and organic phase;Finally, add acid liquor to the organic phase is stripped, and aqueous phase nickel liquid is obtained.The separation method of the application adopts the mode of combination extraction, can make the extraction rate of nickel in lithium nickel mixed material liquid reach 97%~98%, and stripping rate reaches 95%~98%, and while reducing the nickel content in lithium sulfate, the loss rate of lithium is reduced to 1~2%;In addition, the separation method can determine the volume ratio relationship of different extractants in combination extraction according to the component content of different to-be-separated recycled materials, realize objective, quantitative extraction separation method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium-nickel recovery and separation, and particularly relates to a high-efficiency separation method for lithium and nickel in a nickel-lithium mixed solution based on combined extraction. BACKGROUND

[0002] In the development process of the lithium battery industry, the iteration and upgrading of the existing material system is the key to promoting the energy density and realizing the efficiency and cost reduction. The positive electrode material, as a key link in the lithium battery industry chain, is a decisive factor for the electrochemical performance of the lithium battery, directly determines the energy density and safety of the battery, and further affects the comprehensive performance of the battery.

[0003] At present, the development of positive electrode materials mainly focuses on compounds of elements such as nickel, cobalt, manganese and iron phosphate, and the battery precursors are generated through compound reactions, and then react with lithium hydroxide or lithium carbonate to form positive electrode materials. These materials are mainly divided into four categories of lithium cobaltate, lithium manganate, lithium iron phosphate and ternary materials. The full-wet recovery method is generally used to recover ternary positive electrode materials from waste lithium batteries: the waste lithium batteries are disassembled and crushed, and the positive electrode powder with low impurity content is sorted out. After the manganese, nickel, cobalt and lithium in it are reduced and leached, nickel, cobalt and manganese are recovered through extraction process, and lithium is recovered through adding a precipitating agent in the leaching solution or through extraction in the nickel, cobalt and manganese raffinate. However, the existing separation technology usually causes partial loss of lithium during the separation of lithium and nickel in the nickel-lithium mixed solution, resulting in low recovery rate of lithium sulfate solution.

[0004] Therefore, a new lithium-nickel separation method is researched, which can realize efficient recovery and separation regardless of the concentration of the incoming lithium-nickel materials, and reduce the loss of lithium. SUMMARY

[0005] The technical problem to be solved by the application is to realize efficient recovery and separation regardless of the content of the recovered materials, and to reduce the loss of lithium.

[0006] The technical scheme of the application is a high-efficiency separation method for lithium and nickel in a nickel-lithium mixed solution based on combined extraction, which comprises the following steps:

[0007] (1) taking a nickel-lithium mixed solution, and respectively measuring the concentration of lithium and the concentration of nickel in the nickel-lithium mixed solution;

[0008] (2) using a combined extractant composed of extractant A and extractant B, and determining the volumes of extractant A and extractant B according to the following formula:

[0009]

[0010] In the formula, V A is the volume of extractant A; VB is the volume of the extractant B; k ranges from 10 -3 ~10; is the number of moles of H in 1 mol of the extractant A + is the number of moles of H in 1 mol of the extractant B + is the ratio of the number of moles; C Li is the concentration of lithium in the nickel-lithium mixture; C Ni is the concentration of nickel in the nickel-lithium mixture; O / A is the volume ratio of the extractant to the nickel-lithium mixture being extracted;

[0011] (3) After mixing the extractant A and the extractant B, the mixture is added to the nickel-lithium mixture, and liquid alkali is added to adjust the pH value of the mixture to 4-6 for saponification reaction, and the mixture is left to separate into an aqueous phase lithium solution and an organic phase;

[0012] (4) After stirring the water-washed organic phase, the obtained aqueous phase is added to the lithium solution;

[0013] (5) Acid solution is added to the organic phase for back extraction, and the pH value is adjusted to 1-1.5 by stirring, and the mixture is left to separate into an aqueous phase nickel solution.

[0014] The present application can realize efficient recovery and separation and reduce lithium loss by adopting combined extraction, and at the same time, the method can also set the volume ratio relationship of different extractants in combined extraction, so that the volume ratio between different extractants in combined extraction can be set according to the concentration of lithium and nickel in the recovered material, the content of the combined extractant can be determined according to the incoming material, the efficiency and accuracy of extraction are improved on the basis of reducing cost.

[0015] Further, in step (2) of the separation method, the extractant A is one or more of 2-ethyl-2,5-dimethylhexanoic acid, BC191, BC192, BC194, BC196, di(2-ethylhexyl) phosphate, and 2-ethylhexyl 2-ethylhexyl phosphate; the extractant B is one or more of naphthenic acid, 2-octanol, tributyl phosphate, 2-ethyl-2,5-dimethylhexanoic acid, and 4-methyl-2-pentanone.

[0016] Further, in step (2) of the separation method, the volume ratio O / A of the extractant to the nickel-lithium mixture being extracted is (1-10):1.

[0017] Further, in steps (2) and (3) of the separation method, the saponification rate is 30-60%.

[0018] Further, in step (4) of the separation method, the amount of water used for washing the organic phase is 10-50% of the volume of the organic phase.

[0019] Further, in step (5) of the separation method, the volume ratio of the acid liquor to the organic phase used in the back extraction is (0.5-5):1.

[0020] Further, in step (5) of the separation method, the acid used in the back extraction is one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the concentration is 100-300 g / L.

[0021] Advantages: Compared with the prior art, the significant advantages of the present application are that: the separation method uses a combined extraction method, which can make the extraction rate of nickel in the lithium-nickel mixed solution reach 97-98%, the back extraction rate reach 95-98%, and reduce the loss rate of lithium to 1-2% while reducing the content of nickel in the lithium-nickel mixed solution; in addition, the separation method can determine the volume ratio of different extractants in the combined extraction according to the component content of different recovered materials to be separated, and realize an objective and quantitative extraction separation method. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The flowchart of the separation method of the present application. DETAILED DESCRIPTION

[0023] The technical solutions of the present application will be further described in detail below in combination with the drawings and examples.

[0024] As shown in the drawings, Figure 1 The present application realizes a high-efficiency separation method of lithium and nickel in a lithium-nickel mixed solution based on combined extraction, which includes the following steps:

[0025] (1) Take the lithium-nickel mixed solution, and respectively measure the concentration of lithium and the concentration of nickel in the lithium-nickel mixed solution;

[0026] (2) Use a combined extractant composed of extractant A and extractant B, and determine the volumes of extractant A and extractant B according to the following formula:

[0027]

[0028] In the formula, V A is the volume of extractant A; V B is the volume of extractant B; the range of k is 10 -3 -10, k=0.5x extraction rate x extraction stage number when the extraction stage number is two or less, and k=extraction rate x extraction stage number when the extraction stage number is three or more, the extraction rate and the extraction stage number are determined according to actual requirements; is the ratio of the number of moles of H + in 1 mol of extractant A to the number of moles of H + in 1 mol of extractant B; C Li is the concentration of lithium in the lithium-nickel mixed solution; C NiC is the concentration of lithium in the nickel-lithium mixed solution; O / A is the volume ratio of the extractant to the nickel-lithium mixed solution to be extracted;

[0029] (3) After mixing the extractant A and the extractant B, the mixture is added to the nickel-lithium mixed solution, liquid alkali is added to adjust the pH value of the mixed solution to 4-6 to perform saponification reaction, and the mixed solution is left to separate into an aqueous lithium solution and an organic phase.

[0030] (4) After stirring the organic phase, the obtained aqueous phase is added to the lithium solution.

[0031] (5) Acid solution is added to the organic phase for back extraction, and the pH value is adjusted to 1-1.5 by stirring, the mixture is shaken and left to separate into an aqueous nickel solution.

[0032] Example 1

[0033] The nickel-lithium mixed solution obtained in this example 1 is from a ternary positive electrode recovery process.

[0034] This example 1 is a method for efficiently separating lithium and nickel in a nickel-lithium mixed solution based on combined extraction, comprising the following steps:

[0035] (1) The nickel-lithium mixed solution after cobalt-manganese extraction separation in a ternary recovery production line is taken, and the concentration of lithium and the concentration of nickel in the nickel-lithium mixed solution are measured, respectively. The nickel content is about 10 g / L, and the lithium is about 1.5 g / L.

[0036] (2) A combined extractant composed of extractant A (2-ethyl-2,5-dimethylhexanoic acid) and extractant B (naphthenic acid) is used, and the volumes of the extractant A and the extractant B are determined according to the following formula:

[0037]

[0038] In the above formula, the following are determined: k is 2.78; C Li is the concentration of lithium in the nickel-lithium mixed solution 1.5 g / L; C Ni is the concentration of nickel in the nickel-lithium mixed solution 10 g / L; O / A = 2:1; the saponification rate is 40%. Then V A is 100 ml, and V B is 300 ml, and the volume of the nickel-lithium mixed solution is 300 ml.

[0039] (3) After mixing the extractant A and the extractant B, the mixture is added to the nickel-lithium mixed solution, liquid alkali is added to adjust the pH value of the mixed solution to 5.7 to perform saponification reaction, and the mixed solution is left to separate into an aqueous lithium solution and an organic phase.

[0040] (4) Add about 50 mL of water into the organic phase, stir the water-washed organic phase for 10 min, stop stirring and clarify for about 0.5 h to obtain an aqueous phase and an organic phase, and the aqueous phase is added into the lithium liquor.

[0041] (5) Add 500 mL of 200 g / L sulfuric acid into the organic phase of step (4), stir to adjust the pH to about 1.5, detect the pH value multiple times, and stand to separate into layers to obtain a nickel liquor in the aqueous phase.

[0042] The content of each element in the solution after stripping in Example 1 is shown in Table 1.

[0043] Table 1 Content of each element in the solution after stripping in Example 1

[0044]

[0045]

[0046] Comparative Example 1

[0047] The basic steps are the same as in Example 1, except that a single P507 extractant is used to extract nickel, and the content of each element in the solution after stripping is shown in Table 2.

[0048] Table 2 Content of each element in the solution after stripping in Comparative Example 1

[0049]

[0050] Example 2

[0051] The nickel-lithium mixed solution obtained in this Example 2 comes from a ternary positive electrode recovery process.

[0052] This Example 2 is based on a combined extraction to achieve efficient separation of lithium and nickel in a nickel-lithium mixed solution, including the following steps:

[0053] (1) Take the nickel-lithium mixed solution after cobalt-manganese extraction separation from the ternary recovery production line, and respectively determine the concentration of lithium and the concentration of nickel in the nickel-lithium mixed solution. The nickel content is about 10 g / L, and the lithium is about 1.5 g / L;

[0054] (2) Use a combined extractant composed of extractant A (BC191) and extractant B (2-octanol), and determine the volume of extractant A and extractant B according to the following formula:

[0055]

[0056] In the formula, the following are determined: k is 3.70; C Li is the concentration of lithium in the nickel-lithium mixed solution, 1.5 g / L; C NiThe concentration of nickel in the nickel-lithium mixed solution is 10 g / L; O / A = 3:1; the saponification rate is 30%. Then, V is calculated A is 200 ml, and the volume of the nickel-lithium mixed solution is 200 ml. B is 400 ml, and the volume of the nickel-lithium mixed solution is 200 ml.

[0057] (3) After mixing the extractant A and the extractant B, the mixture is added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 5.4 for saponification reaction. After mixing, standing, and clarifying for 0.5 h, the aqueous phase lithium solution and the organic phase are obtained.

[0058] (4) About 80 mL of water is added to the organic phase, the organic phase is stirred for 10 min, then the stirring is stopped and the solution is clarified for about 0.5 h, to obtain the aqueous phase and the organic phase, and the aqueous phase is combined with the lithium solution.

[0059] (5) 1200 mL of 150 g / L sulfuric acid is added to the organic phase of step (4), the pH value is adjusted to about 1.5, the pH value is detected multiple times, and the solution is standing and layered to obtain the aqueous phase nickel solution.

[0060] The content of each element in the solution after stripping in Example 2 is shown in Table 3.

[0061] Table 3 Content of each element in the solution after stripping in Example 2

[0062]

[0063] Example 3

[0064] The nickel-lithium mixed solution obtained in this example 3 comes from the ternary positive electrode recovery process.

[0065] This example 3 is based on a combined extraction to achieve efficient separation of lithium and nickel in a nickel-lithium mixed solution, including the following steps:

[0066] (1) The nickel-lithium mixed solution after cobalt-manganese extraction separation in the ternary recovery production line is taken, and the concentration of lithium and the concentration of nickel in the nickel-lithium mixed solution are measured, respectively. The nickel content is about 10 g / L, and the lithium is about 1.5 g / L;

[0067] (2) A combined extractant composed of extractant A (di(2-ethylhexyl) phosphate) and extractant B (tributyl phosphate) is used, and the volume of the extractant A and the extractant B is determined according to the following formula:

[0068]

[0069] In the formula, k is 2.78; C is the concentration of lithium in the nickel-lithium mixed solution, 1.5 g / L; C Li is the concentration of nickel in the nickel-lithium mixed solution, 10 g / L; and V NiThe nickel concentration in the nickel-lithium mixture was 10 g / L; the O / A ratio was 2:1; and the saponification rate was 30%. V was then calculated. A For 600ml, V B The volume of the nickel-lithium mixture is 1200ml, and the volume of the nickel-lithium mixture is 900ml.

[0070] (3) After mixing extractant A and extractant B, add them to the nickel-lithium mixture. Add liquid alkali to adjust the pH of the mixture to 5.2 and carry out the saponification reaction. After mixing, standing, and clarifying for 0.5 h, the mixture is separated into aqueous lithium liquid and organic phase.

[0071] (4) Add about 240 mL of water to the organic phase, stir and wash the organic phase for 10 min, then stop stirring and clarify for about 0.5 h to obtain the aqueous phase and the organic phase. The aqueous phase is then added to the lithium solution.

[0072] (5) Add 1800 mL of 200 g / L sulfuric acid to the organic phase in step (4), stir to adjust the pH to about 1.5, check the pH value multiple times, let it stand to separate into layers, and obtain an aqueous nickel solution.

[0073] The elemental contents of the solution after back-extraction in Example 3 are shown in Table 3 below.

[0074] Table 4. Element content in the solution after back-extraction in Example 3

[0075]

[0076] Example 4

[0077] Example 4 describes a method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction, comprising the following steps:

[0078] (1) Take a nickel-lithium mixture and determine the concentration of lithium and nickel in the mixture. The nickel content is about 20 g / L and the lithium content is about 3.7 g / L.

[0079] (2) A combined extractant consisting of extractant A (2-ethylhexyl phosphate, 2-ethylhexyl ester) and extractant B (4-methyl-2-pentanone) is used, and the volumes of extractant A and extractant B are determined according to the following formula:

[0080]

[0081] Among them, the following is determined in the above formula: k is 1.45; C Li The lithium concentration in the nickel-lithium mixture was 3.7 g / L; C Ni The nickel concentration in the nickel-lithium mixture was 20 g / L; the O / A ratio was 4:1; and the saponification rate was 40%. V was then calculated. A For 300ml, V BThe volume of the nickel-lithium mixture is 700ml, and the volume of the nickel-lithium mixture is 2500ml.

[0082] (3) After mixing extractant A and extractant B, add them to the nickel-lithium mixture. Add liquid alkali to adjust the pH of the mixture to 5.8 and carry out the saponification reaction. After mixing, standing, and clarifying for 0.5 h, the mixture is separated into aqueous lithium liquid and organic phase.

[0083] (4) Add about 100 mL of water to the organic phase, stir and wash the organic phase for 10 min, then stop stirring and clarify for about 0.5 h to obtain the aqueous phase and the organic phase. The aqueous phase is then added to the lithium solution.

[0084] (5) Add 1500 mL of 200 g / L sulfuric acid to the organic phase in step (4), stir to adjust the pH to about 1.5, check the pH value multiple times, let it stand to separate into layers, and obtain an aqueous nickel solution.

[0085] The element content of the solution after back-extraction in Example 4 is shown in Table 5 below.

[0086] Table 5. Element content in the solution after back-extraction in Example 4

[0087]

[0088] Example 5

[0089] Example 5 describes a method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction, comprising the following steps:

[0090] (1) Take a nickel-lithium mixture and determine the concentration of lithium and nickel in the mixture. The nickel content is about 2.8 g / L and the lithium content is about 14 g / L.

[0091] (2) A combination extractant consisting of extractant A (BC196) and extractant B (4-methyl-2-pentanone) is used, and the volumes of extractant A and extractant B are determined according to the following formula;

[0092]

[0093] Among them, the following is determined in the above formula: k is 0.86; C Li The lithium concentration in the nickel-lithium mixture is 14 g / L; C Ni The nickel concentration in the nickel-lithium mixture was 2.8 g / L; the O / A ratio was 1:1; and the saponification rate was 35%. V was then calculated. A For 600ml, V B The volume of the nickel-lithium mixture is 400ml, and the volume of the nickel-lithium mixture is 1000ml.

[0094] (3) After mixing the extractant A and the extractant B, the mixture is added into the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 5.7 to perform saponification reaction, and after standing and clarifying for 0.5 h, the organic phase and the aqueous phase are separated, and the aqueous phase is obtained.

[0095] (4) About 100 mL of water is added into the organic phase, the organic phase is stirred for 10 min, and then the stirring is stopped and the organic phase is clarified for about 0.5 h to obtain the aqueous phase and the organic phase, and the aqueous phase is combined with the lithium solution.

[0096] (5) 1500 mL of 200 g / L sulfuric acid is added into the organic phase of step (4), the pH value is adjusted to about 1.5, the pH value is detected for multiple times, and then the organic phase is standing and separated to obtain the aqueous phase.

[0097] The content of each element in the solution after stripping in Example 5 is shown in Table 6.

[0098] Table 6 Content of each element in the solution after stripping in Example 5

[0099]

[0100]

[0101] It can be seen from the above examples that the separation method of the present application can determine the volume ratio of different extractants in the combined extraction according to the content of different components in the recycled material to be separated, so as to realize an objective and quantitative extraction separation method. The separation method adopts the combined extraction mode, so that the extraction rate of nickel in the lithium-nickel mixed solution can reach 97% to 98%, the stripping rate can reach 95% to 98%, and the loss rate of lithium is reduced to 1% to 2% while reducing the content of nickel in lithium sulfate.

[0102] In addition to the above examples, the separation steps and process parameters of the present application can also achieve the technical effects claimed above. For example, the extractant A can also include at least one of 2-ethyl-2,5-dimethylhexanoic acid, BC191, BC192, BC194, BC196, di(2-ethylhexyl) phosphate, and 2-ethylhexyl 2-ethylhexyl phosphate. The extractant B can also include at least one of naphthenic acid, 2-octanol, tributyl phosphate, 2-ethyl-2,5-dimethylhexanoic acid, and 4-methyl-2-pentanone. The volume ratio of the extractant to the nickel-lithium mixed solution to be extracted (O / A) can also be (1-10):1. The saponification rate can also be 30% to 60%. The amount of water used for washing the organic phase can also be 10% to 50% of the volume of the organic phase. The volume ratio of the acid solution to the organic phase used for stripping can also be (0.5-5):1. The acid used for stripping can also be one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the concentration thereof is 100-300 g / L.

Claims

1. A method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction, characterized in that, Includes the following steps: (1) Take a nickel-lithium mixture and determine the concentration of lithium and the concentration of nickel in the mixture respectively; (2) A combined extractant consisting of extractant A and extractant B is used, and the volumes of extractant A and extractant B are determined according to the following formula; wherein extractant A is one or more of 2-ethyl-2,5-dimethylhexanoic acid, BC191, BC192, BC194, BC196, and 2-ethylhexyl phosphate; and extractant B is one or more of naphthenic acid, 2-octanol, tributyl phosphate, and 4-methyl-2-pentanone. ； In the formula: V A V is the volume of extractant A; B The volume of extractant B; k ranges from 10. -3 ~10; H in 1 mol of extractant A + The number of moles and the amount of H in 1 mol of extractant B + The ratio of the number of moles; This represents the concentration of lithium in the nickel-lithium mixture. O / A represents the concentration of nickel in the nickel-lithium mixture; O / A is the volume ratio of the extractant to the extracted nickel-lithium mixture. (3) After mixing extractant A and extractant B, add them to the nickel-lithium mixture, add liquid alkali to adjust the pH of the mixture to 4-6 to carry out the saponification reaction, mix and let stand to separate the layers to obtain the aqueous lithium liquid and the organic phase; (4) After stirring and washing the organic phase with water, the obtained aqueous phase is incorporated into the lithium solution; (5) Add acid to back-extract the organic phase, stir to adjust the pH to 1~1.5, shake to mix and let stand to separate the layers to obtain aqueous nickel solution.

2. The method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction according to claim 1, characterized in that, In step (2), the volume ratio O / A of the extractant to the extracted nickel-lithium mixture is (1~10):

1.

3. The method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction according to claim 1, characterized in that, In steps (2) and (3), the saponification rate is 30-60%.

4. The method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction according to claim 1, characterized in that, In step (4), the amount of water used for washing the organic phase is 10-50% of the volume of the organic phase.

5. The method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction according to claim 1, characterized in that, In step (5), the volume ratio of acid solution to organic phase used in the back-extraction is (0.5~5):

1.

6. The method for efficient separation of lithium and nickel in a nickel-lithium mixture based on combined extraction according to claim 1 or 5, characterized in that, In step (5), the acid used for back-extraction is one or more of sulfuric acid, hydrochloric acid, and nitric acid, with a concentration of 100~300 g / L.

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