Method for realizing efficient separation of lithium and nickel in nickel-lithium mixed solution based on combined extraction

Abstract

The invention discloses a method for efficiently separating lithium and nickel in a nickel-lithium mixed solution based on combined extraction. The method comprises the following steps: respectively measuring the concentration of lithium and the concentration of nickel in the nickel-lithium mixed solution; a combined extracting agent composed of an extracting agent A and an extracting agent B is adopted, and the volume of the two is determined according to a specific formula; adding the combined extracting agent into the nickel-lithium mixed solution, and saponifying to obtain a water-phase lithium solution and an organic phase; and finally, acid liquor is added for reverse extraction of the organic phase, and water-phase nickel liquid is obtained. According to the separation method, a combined extraction mode is adopted, the extraction rate of nickel in the lithium-nickel mixed material liquid can reach 97%-98%, the reverse extraction rate can reach 95%-98%, and the loss rate of lithium is reduced to 1%-2% while the nickel content in lithium sulfate is reduced; besides, according to the separation method, the volume proportion relation of different extraction agents in combined extraction can be determined according to the component contents of different to-be-separated recycled materials, and the objective and quantitative extraction separation method is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium nickel recovery and separation, and in particular relates to a method for efficiently separating lithium and nickel from a nickel-lithium mixed solution based on combined extraction. Background Art

[0002] In the development process of the lithium battery industry, the iterative upgrade of the existing material system is the key to promoting energy density improvement and achieving efficiency increase and cost reduction. As a key link in the lithium battery industry chain, the positive electrode material is the decisive factor in the electrochemical performance of lithium batteries, directly determining the energy density and safety of the battery, and thus affecting the overall performance of the battery.

[0003] At present, the development of positive electrode materials is mainly focused on compounds of elements such as nickel, cobalt, manganese and iron phosphate, and the battery precursor is generated through compound reaction, and then reacted with lithium hydroxide or lithium carbonate to form positive electrode materials. These materials are mainly divided into four categories: lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate and ternary materials. The domestic recovery of ternary positive electrode materials from waste lithium batteries generally adopts the full wet recovery method: dismantle and crush the waste lithium batteries, and sort out the positive electrode powder with low impurity content, and reduce and leach the manganese, nickel, cobalt and lithium together, and then recover nickel, cobalt and manganese through extraction and other processes. Lithium is recovered by adding a precipitant to the leachate or by extraction in the nickel-cobalt-manganese raffinate. However, the existing separation technology is usually accompanied by partial loss of lithium in the process of separating lithium and nickel from the nickel-lithium mixed solution, resulting in a low recovery rate of lithium sulfate solution.

[0004] Based on this, a new lithium-nickel separation method is now being studied. This method can achieve efficient recovery and separation and reduce lithium loss regardless of the lithium-nickel concentration of the incoming materials. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to achieve efficient recovery and separation of recycled materials with any lithium-nickel content, and at the same time reduce lithium loss.

[0006] Technical solution: The present invention realizes a highly efficient separation method of lithium and nickel in a nickel-lithium mixed solution based on combined extraction, comprising 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 consisting of extractant A and extractant B, and determining the volumes of both extractant A and extractant B according to the following formula;

[0009]

[0010] Where: V A is the volume of extractant A; VB is the volume of extractant B; the range of k is 10 -3 ~10; is 1 mol of H in extractant A + The number of moles is related to the H in 1 mol of extractant B. + Mole ratio; C Li is the concentration of lithium in the nickel-lithium mixture; C Ni is the concentration of nickel in the nickel-lithium mixed solution; O / A is the volume ratio of the extractant to the extracted nickel-lithium mixed solution;

[0011] (3) extractant A and extractant B are mixed and added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 4-6 for saponification reaction, and the mixture is allowed to stand for separation to obtain an aqueous lithium liquid phase and an organic phase;

[0012] (4) After washing the organic phase with water by stirring, the obtained aqueous phase is incorporated into the lithium solution;

[0013] (5) adding acid solution to strip the organic phase, stirring to adjust the pH to 1-1.5, shaking to mix and standing to separate the layers, and obtaining an aqueous nickel solution.

[0014] The present invention can realize efficient recovery and separation and reduce lithium loss by adopting combined extraction. At the same time, the method can also set the volume ratio relationship of different extractants in the combined extraction, thereby realizing that no matter what kind of recycled material is, the concentration of lithium and nickel in the recycled material can be measured, that is, the volume ratio between different extractants in the combined extraction can be tailored to determine the content of the combined extractant according to the incoming material, thereby improving the efficiency and accuracy of extraction on the basis of reducing costs.

[0015] Furthermore, 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 phosphate 2-ethylhexyl ester; and the extractant B is one or more of cyclohexane acid, 2-octanol, tributyl phosphate, 2-ethyl-2,5-dimethylhexanoic acid, and 4-methyl-2-pentanone.

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

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

[0018] Furthermore, in step (4) of the separation method, the amount of water used to wash the organic phase is 10 to 50% of the volume of the organic phase.

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

[0020] Furthermore, in step (5) of the separation method, the acid used for the stripping is one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the concentration thereof is 100 to 300 g / L.

[0021] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the separation method adopts a combined extraction method, which can make the nickel extraction rate in the lithium-nickel mixed liquid reach 97-98%, the stripping rate reach 95-98%, and reduce the nickel content in the nickel-lithium mixed liquid while reducing the lithium loss rate to 1-2%; in addition, the separation method can determine the volume ratio relationship of different extractants in the combined extraction according to the component content of different recycled materials to be separated, thereby realizing an objective and quantitative extraction and separation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart of the separation method of the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, the present invention realizes a highly efficient separation method of lithium and nickel in a nickel-lithium mixed solution based on combined extraction, comprising the following steps:

[0025] (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;

[0026] (2) Using a combined extractant consisting of extractant A and extractant B, and determining the volumes of both extractant A and extractant B according to the following formula;

[0027]

[0028] Where: V A is the volume of extractant A; V B is the volume of extractant B; the range of k is 10 -3 ~10, when the extraction stage is two or less, k = 0.5 × extraction rate × extraction stage, and when the extraction stage is three or more, k = extraction rate × extraction stage, the extraction rate and extraction stage are determined according to actual needs; is 1 mol of H in extractant A + The number of moles is related to the H in 1 mol of extractant B. + Mole ratio; C Li is the concentration of lithium in the nickel-lithium mixture; C Niis the concentration of nickel in the nickel-lithium mixed solution; O / A is the volume ratio of the extractant to the extracted nickel-lithium mixed solution;

[0029] (3) extractant A and extractant B are mixed and added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 4-6 for saponification reaction, and the mixture is allowed to stand for separation to obtain an aqueous lithium liquid phase and an organic phase;

[0030] (4) After washing the organic phase with water by stirring, the obtained aqueous phase is incorporated into the lithium solution;

[0031] (5) adding acid solution to strip the organic phase, stirring to adjust the pH to 1-1.5, shaking to mix and standing to separate the layers, and obtaining an aqueous nickel solution.

[0032] Example 1

[0033] The nickel-lithium mixed solution obtained in Example 1 is produced from the ternary positive electrode recovery process.

[0034] This embodiment 1 is based on combined extraction to achieve efficient separation of lithium nickel in nickel-lithium mixed solution, comprising the following steps:

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

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

[0037]

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

[0039] (3) Extractant A and extractant B are mixed and added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 5.7 for saponification reaction. After mixing, standing and clarifying for 0.5 h, the layers are separated to obtain an aqueous lithium liquid and an organic phase.

[0040] (4) Add about 50 mL of water to the organic phase, stir and wash the organic phase for 10 minutes, then stop stirring and clarify for about 0.5 hours to obtain an aqueous phase and an organic phase, and merge the aqueous phase into the lithium solution.

[0041] (5) Add 500 mL of 200 g / L sulfuric acid to the organic phase of step (4), stir and adjust the pH to about 1.5, detect the pH value several times, let stand and separate, and obtain an aqueous nickel solution.

[0042] The contents of various elements in the solution after stripping in Example 1 are shown in Table 1 below.

[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 those in Example 1, except that a single P507 extractant is used to extract nickel. The contents of each element in the solution after stripping are shown in Table 2 below.

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

[0049]

[0050] Example 2

[0051] The nickel-lithium mixed solution obtained in Example 2 is produced from the ternary positive electrode recovery process.

[0052] This embodiment 2 is based on combined extraction to achieve an efficient separation method of lithium nickel in a nickel-lithium mixed solution, comprising the following steps:

[0053] (1) taking a nickel-lithium mixed solution obtained after cobalt-manganese extraction and separation in a ternary recovery production line, and measuring the lithium concentration and nickel concentration in the nickel-lithium mixed solution, respectively; the nickel content is about 10 g / L, and the lithium content is about 1.5 g / L;

[0054] (2) A combined extractant consisting of extractant A (BC191) and extractant B (2-octanol) was used, and the volumes of extractant A and extractant B were determined according to the following formula:

[0055]

[0056] Among them, determine the above formula: k is 3.70; C Li The concentration of lithium in the nickel-lithium mixture is 1.5 g / L; C NiThe nickel concentration in the nickel-lithium mixed solution is 10 g / L; O / A = 3:1; and the saponification rate is 30%. Then V A For 200ml, V B The volume of the nickel-lithium mixed solution is 400ml, and the volume of the nickel-lithium mixed solution is 200ml.

[0057] (3) Extractant A and extractant B are mixed and 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 layers are separated to obtain an aqueous lithium liquid and an organic phase.

[0058] (4) Add about 80 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 an aqueous phase and an organic phase, and merge the aqueous phase into the lithium solution.

[0059] (5) Add 1200 mL of 150 g / L sulfuric acid to the organic phase of step (4), stir and adjust the pH to about 1.5, detect the pH value several times, stand and separate, and obtain an aqueous nickel solution.

[0060] The contents of various elements in the solution after stripping in Example 2 are shown in Table 3 below.

[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 Example 3 is produced from the ternary positive electrode recovery process.

[0065] This embodiment 3 is based on combined extraction to achieve an efficient separation method of lithium nickel in a nickel-lithium mixed solution, comprising the following steps:

[0066] (1) taking a nickel-lithium mixed solution obtained after cobalt-manganese extraction and separation in a ternary recovery production line, and measuring the lithium concentration and nickel concentration in the nickel-lithium mixed solution, respectively; the nickel content is about 10 g / L, and the lithium content is about 1.5 g / L;

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

[0068]

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

[0070] (3) Extractant A and extractant B are mixed and added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 5.2 for saponification reaction. After mixing, standing and clarifying for 0.5 h, the layers are separated to obtain an aqueous lithium liquid and an 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 an aqueous phase and an organic phase, and merge the aqueous phase into the lithium solution.

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

[0073] The contents of various elements in the solution after stripping in Example 3 are shown in Table 3 below.

[0074] Table 4 Content of each element in the solution after stripping in Example 3

[0075]

[0076] Example 4

[0077] This embodiment 4 is based on combined extraction to achieve an efficient separation method of lithium nickel in a nickel-lithium mixed solution, comprising the following steps:

[0078] (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, 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) 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, determine the above formula: k is 1.45; C Li The concentration of lithium in the nickel-lithium mixture is 3.7 g / L; C Ni The nickel concentration in the nickel-lithium mixed solution is 20 g / L; O / A = 4:1; and the saponification rate is 40%. Then V A For 300ml, V BThe volume of the nickel-lithium mixed solution is 700ml, and the volume of the nickel-lithium mixed solution is 2500ml.

[0082] (3) Extractant A and extractant B are mixed and added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 5.8 for saponification reaction. After mixing, standing and clarifying for 0.5 h, the layers are separated to obtain an aqueous lithium liquid and an organic phase.

[0083] (4) Add about 100 mL of water to the organic phase, stir and wash the organic phase for 10 minutes, then stop stirring and clarify for about 0.5 hours to obtain an aqueous phase and an organic phase, and merge the aqueous phase into the lithium solution.

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

[0085] The contents of various elements in the solution after stripping in Example 4 are shown in Table 5 below.

[0086] Table 5 Content of each element in the solution after stripping in Example 4

[0087]

[0088] Example 5

[0089] This embodiment 5 is based on combined extraction to achieve an efficient separation method of lithium nickel in a nickel-lithium mixed solution, comprising the following steps:

[0090] (1) taking a nickel-lithium mixed solution, and measuring the lithium concentration and the nickel concentration in the nickel-lithium mixed solution respectively, the nickel content is about 2.8 g / L, and the lithium content is about 14 g / L;

[0091] (2) Using a combined extractant consisting of extractant A (BC196) and extractant B (4-methyl-2-pentanone), and determining the volumes of both extractant A and extractant B according to the following formula;

[0092]

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

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

[0095] (4) Add about 100 mL of water to the organic phase, stir and wash the organic phase for 10 minutes, then stop stirring and clarify for about 0.5 hours to obtain an aqueous phase and an organic phase, and merge the aqueous phase into the lithium solution.

[0096] (5) Add 1500 mL of 200 g / L sulfuric acid to the organic phase of step (4), stir and adjust the pH to about 1.5, detect the pH value several times, let stand and separate, and obtain an aqueous nickel solution.

[0097] The contents of various elements in the solution after stripping in Example 5 are shown in Table 6 below.

[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 embodiments that the separation method of the present invention can determine the volume ratio of different extractants in the combined extraction according to the component content of different recycled materials to be separated, and realize an objective and quantitative extraction separation method. And the separation method adopts a combined extraction method, which can make the nickel extraction rate in the lithium-nickel mixed liquid reach 97% to 98%, the stripping rate reach 95% to 98%, and reduce the loss rate of lithium to 1 to 2% while reducing the nickel content in lithium sulfate.

[0102] In addition to the above embodiments, the separation steps and process parameters of the present invention can achieve the above-mentioned technical effects. For example, the extractant A used can also include at least one of 2-ethyl-2,5-dimethylhexanoic acid, BC191, BC192, BC194, BC196, di(2-ethylhexyl) phosphate, and 2-ethylhexyl phosphate 2-ethylhexyl ester. The extractant B can also include at least one of cyclohexane acid, 2-octanol, tributyl phosphate, 2-ethyl-2,5-dimethylhexanoic acid, and 4-methyl-2-pentanone. The volume ratio O / A of the extractant to the extracted nickel-lithium mixed solution can also be (1-10):1. The saponification rate can also be 30-60%. The amount of water used for washing the organic phase can also be 10-50% of the volume of the organic phase. The volume ratio of the acid solution used in the back extraction to the organic phase 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, with a concentration of 100 to 300 g / L.

Claims

1. A method for efficiently separating lithium and nickel from a nickel-lithium mixed solution based on combined extraction, characterized in that: The steps include: (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; (2) Using a combined extractant consisting of extractant A and extractant B, and determining the volumes of both extractant A and extractant B according to the following formula; Where: V A is the volume of extractant A; V B is the volume of extractant B; the range of k is 10 -3 ~10; is 1 mol of H in extractant A + The number of moles is related to the H in 1 mol of extractant B. + Mole ratio; C Li is the concentration of lithium in the nickel-lithium mixture; C Ni is the concentration of nickel in the nickel-lithium mixed solution; O / A is the volume ratio of the extractant to the extracted nickel-lithium mixed solution; (3) extractant A and extractant B are mixed and added to the nickel-lithium mixed solution, and liquid alkali is added to adjust the pH value of the mixed solution to 4-6 for saponification reaction, and the mixture is allowed to stand for separation to obtain an aqueous lithium liquid phase and an organic phase; (4) After washing the organic phase with water by stirring, the obtained aqueous phase is incorporated into the lithium solution; (5) adding acid solution to strip the organic phase, stirring to adjust the pH to 1-1.5, shaking to mix and standing to separate the layers, and obtaining an aqueous nickel solution.

2. The method for efficiently separating lithium and nickel from a nickel-lithium mixed solution based on combined extraction according to claim 1, characterized in that: In step (2), 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 phosphate 2-ethylhexyl ester; the extractant B is one or more of cyclohexane acid, 2-octanol, tributyl phosphate, 2-ethyl-2,5-dimethylhexanoic acid, and 4-methyl-2-pentanone.

3. The method for efficiently separating lithium and nickel from a nickel-lithium mixed solution 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 mixed solution is (1-10):

1.

4. The method for efficiently separating lithium and nickel from a nickel-lithium mixed solution based on combined extraction according to claim 1, characterized in that: In step (2) and step (3), the saponification rate is 30-60%.

5. The method for efficiently separating lithium and nickel from a nickel-lithium mixed solution 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 to 50% of the volume of the organic phase.

6. The method for efficiently separating lithium and nickel from a nickel-lithium mixed solution based on combined extraction according to claim 1, characterized in that: In step (5), the volume ratio of the acid solution to the organic phase used in the stripping is (0.5-5):

1.

7. The method for efficiently separating lithium and nickel from a nickel-lithium mixed solution based on combined extraction according to claim 1 or 6, characterized in that: In step (5), the acid used for the stripping is one or more of sulfuric acid, hydrochloric acid, and nitric acid, and its concentration is 100 to 300 g / L.

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