Method for removing iron and aluminum from ternary lithium ion battery leachate

Abstract

The invention provides a method for removing iron and aluminum from a ternary lithium ion battery leachate, which comprises the following steps: mixing the ternary lithium ion battery leachate with phosphoric acid to precipitate iron and aluminum in the leachate; and after iron and aluminum in the leaching solution are precipitated, adjusting the pH value of the leaching solution back by adopting an alkaline substance, and then continuously reacting to obtain an iron and aluminum precipitate and a valuable metal solution, so that the removal of iron and aluminum in the ternary lithium ion battery leaching solution is realized. According to the method, the difference of solubility products of phosphate in a solution is utilized, phosphoric acid is added into the leaching solution firstly, then alkaline matter is added to adjust the pH value, aluminum and iron impurities can be effectively removed, valuable metal is left in the form of the solution, and separation of the valuable metal and impurity metal is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgical metal recovery and relates to a method for removing iron and aluminum from a ternary lithium-ion battery leachate. Background Art

[0002] Lithium-ion batteries have been widely used in mobile communications, electric vehicles, and energy storage due to their high energy density, light weight, and long life. Among them, ternary lithium-ion batteries have become one of the mainstream products on the market due to their advantages in energy and power performance. However, after ternary lithium-ion batteries reach the end of their service life, how to effectively recycle the valuable metal elements in them and reduce environmental pollution has become an urgent problem to be solved.

[0003] The positive electrode material of ternary lithium-ion batteries is mainly composed of three metal elements: nickel, cobalt and manganese. This battery combines the advantages of three metal materials and improves the overall performance of the battery. However, waste ternary lithium-ion batteries contain a large amount of metal impurities, such as copper, iron, aluminum, etc. The presence of these impurities seriously affects the recovery efficiency and purity of valuable metal elements. Therefore, developing an effective method for removing iron and aluminum is of great significance to improving the recycling rate of ternary lithium-ion batteries.

[0004] In the recycling process of waste ternary lithium-ion batteries, the selective leaching technology in the chemical method has attracted widespread attention due to its high efficiency and environmental protection. Through the leaching process, valuable metal elements such as cobalt and nickel can be separated to achieve resource reuse. However, the leachate still contains a large amount of impurities such as iron and aluminum, which need further treatment.

[0005] Based on the above research, it is necessary to provide a method for removing iron and aluminum from the leachate of a ternary lithium-ion battery, which can effectively remove impurities such as iron and aluminum in the leachate and improve the recovery efficiency and purity of valuable metal elements. Summary of the invention

[0006] The object of the present invention is to provide a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method utilizes the difference in solubility product of phosphate in a solution. By first adding phosphoric acid to the leachate and then adding an alkaline substance to adjust the pH, aluminum and iron impurities can be effectively removed, and cobalt, nickel and manganese are left in the form of a solution, thereby achieving separation of valuable metals and impurity metals.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate, the method comprising the following steps:

[0009] (1) mixing the ternary lithium-ion battery leachate with phosphoric acid to precipitate iron and aluminum in the leachate;

[0010] (2) After the iron and aluminum in the leachate of step (1) are precipitated, an alkaline substance is used to adjust the pH of the leachate, and then the reaction is continued to obtain an iron and aluminum precipitate and a valuable metal solution, thereby achieving the removal of iron and aluminum in the leachate of the ternary lithium-ion battery.

[0011] The present invention utilizes the difference in solubility product of phosphate in solution, adds phosphoric acid to the ternary lithium ion battery leachate, makes the iron and aluminum in the leachate fully precipitate, after the iron and aluminum are completely precipitated, uses alkaline substances to adjust the pH of the leachate and continues the reaction, optimizes the precipitation stability, ensures that the iron and aluminum precipitation is more thorough and more stable, prevents the loss of valuable metal elements, reduces the acid load of subsequent processes, and provides a suitable pH environment for subsequent steps (such as extraction or precipitation recovery of valuable metals). Therefore, the method of the present invention can effectively remove iron and aluminum impurities in the leachate, and improve the recovery efficiency and purity of valuable metal elements.

[0012] Preferably, the molar amount of phosphoric acid added in step (1) is 1 to 2.5 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, for example, it can be 1 times, 1.25 times, 1.5 times, 1.75 times or 2.5 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] The amount of phosphoric acid added in step (1) of the present invention corresponds to the content of aluminum and iron impurities contained in the leaching solution to ensure the effective removal of aluminum and iron. It is preferred to add an excess of phosphoric acid relative to aluminum and iron to ensure complete precipitation of aluminum and iron. However, it is not advisable to add too much phosphoric acid. If there is too much phosphoric acid, the excess phosphoric acid will cause the target metal (such as nickel and cobalt) to be co-precipitated and lost. In addition, the excess phosphoric acid and Fe 3+ Forming soluble complexes (such as Fe(HPO 4 ) 2- ), and redissolve at pH>4; and if excessive phosphoric acid is used, the viscosity of the solution will increase, making filtration difficult.

[0014] Preferably, the ternary lithium ion battery leachate in step (1) includes 0.16-0.24 mol / L of Ni ions, for example, 0.16 mol / L, 0.18 mol / L, 0.20 mol / L, 0.22 mol / L or 0.24 mol / L, 0.08-0.12 mol / L of Co ions, for example, 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.11 mol / L or 0.12 mol / L, 0.08-0.12 mol / L of Mn ions, for example, 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.11 mol / L or 0.12 mol / L, 0. 0.08~0.12mol / L of Cu ions, for example, can be 0.08mol / L, 0.09mol / L, 0.10mol / L, 0.11mol / L or 0.12mol / L, 0.08~0.12mol / L of Al ions, for example, can be 0.08mol / L, 0.09mol / L, 0.10mol / L, 0.11mol / L or 0.12mol / L, 0.08~0.12mol / L of Fe ions, for example, can be 0.08mol / L, 0.09mol / L, 0.10mol / L, 0.11mol / L or 0.12mol / L, but are not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0015] Preferably, the mixing temperature in step (1) is 25-90°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the mixing time in step (1) is 1 to 2 hours, for example, 1 hour, 1.25 hours, 1.5 hours, 1.75 hours or 2 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the pH of the adjusted leaching solution in step (2) is between 2.5 and 4, for example, 2.5, 2.75, 3, 3.25, 3.5 or 4, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] The present invention uses alkaline substances to adjust the pH of the leaching solution to a specific range. If the adjusted pH value is too small, the strong acidic environment may dissolve the precipitated phosphate and release Fe 3+ / Al 3+Returning to the solution, forming "secondary pollution", the impurity aluminum and iron cannot be precipitated or precipitate less, affecting the subsequent filtration. 2+ 、Co2 + At high pH, ​​hydroxide precipitation is easily generated, Ca 2+ Mg 2+ Impurity ions such as iron phosphate form phosphate precipitates, increasing the amount of solid waste; and iron / aluminum phosphate precipitates tend to form colloidal suspensions when pH>4.0, making solid-liquid separation difficult.

[0019] Preferably, the pH regulator used for adjusting the pH of the leachate in step (2) includes any one of lime milk, sodium hydroxide solution or potassium hydroxide solution or a combination of at least two of them, preferably a sodium hydroxide solution with a concentration of 5 to 15wt%, for example, 5wt%, 7.5wt%, 10wt%, 12.5wt% or 15wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the reaction time of step (2) is 0.5 to 1 h, for example, 0.5 h, 0.625 h, 0.75 h, 0.875 h or 1 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the temperature for continuing the reaction in step (2) is 25-90°C, for example, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the reaction in step (2) is continued and then filtered to obtain an iron-aluminum precipitate and a valuable metal solution.

[0023] Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Al is ≥99%, for example, it can be 99%, 99.2%, 99.4%, 99.6%, 99.8%, 99.9% or 100%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Fe is ≥99%, for example, it can be 99%, 99.2%, 99.4%, 99.6%, 99.8%, 99.9% or 100%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Co is ≤10%, for example, it can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3% or 2%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Ni is ≤9%, for example, it can be 9%, 8%, 7%, 6%, 5%, 4%, 3% or 2%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Mn is ≤16%, for example, it can be 16%, 14%, 12%, 10%, 8%, 6%, 4% or 2%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The method of the present invention utilizes the different solubility products of phosphates in the solution to achieve highly selective removal of Fe and Al in the leachate. The removal rates of Fe and Al can be as high as 100%, respectively, while the precipitation of valuable metals is less. This high removal rate ensures the effective separation of impurity metals and valuable metals in the leachate, providing high-quality raw materials for subsequent metal recycling.

[0030] (2) The method of the present invention has a simple process, continuous operation, and is easy to realize industrial production. It can ensure the consistency and stability of the removal effect, improve production efficiency and product quality, and the leaching solution after removing iron and aluminum is purer, which provides better raw materials for subsequent metal recovery and purification. This not only helps to improve the quality of the final product, but also enhances the market competitiveness of the product, thereby helping to alleviate the problem of resource shortage and reduce the risk of environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of the method described in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The flow chart of the method is as follows: Figure 1 As shown, the following steps are included:

[0035] (1) At a temperature of 25° C., the ternary lithium-ion battery leachate is mixed with phosphoric acid for 2 hours to precipitate iron and aluminum in the leachate;

[0036] The ternary lithium-ion battery leachate includes 0.2 mol / L Ni ions, 0.1 mol / L Co ions, 0.1 mol / L Mn ions, 0.1 mol / L Cu ions, 0.1 mol / L Al ions and 0.1 mol / L Fe ions;

[0037] The molar amount of phosphoric acid added is 1.2 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, specifically 0.24 mol / L in the leachate;

[0038] (2) After the iron and aluminum in the leachate of step (1) are completely precipitated, the pH value of the leachate is adjusted to 3.91 using a 10 wt % liquid alkali, and then the reaction is continued at 25° C. for 1 hour. After the reaction is completed, the iron and aluminum precipitates and the valuable metal solution are obtained by suction filtration, thereby achieving the removal of iron and aluminum in the leachate of the ternary lithium-ion battery.

[0039] Example 2

[0040] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate, the method comprising the following steps:

[0041] (1) The ternary lithium-ion battery leachate is mixed with phosphoric acid at 70°C for 2 hours to precipitate iron and aluminum in the leachate;

[0042] The ternary lithium-ion battery leachate includes 0.2 mol / L Ni ions, 0.1 mol / L Co ions, 0.1 mol / L Mn ions, 0.1 mol / L Cu ions, 0.1 mol / L Al ions and 0.1 mol / L Fe ions;

[0043] The molar amount of phosphoric acid added is 2.4 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, specifically 0.48 mol / L in the leachate;

[0044] (2) After the iron and aluminum in the leachate of step (1) are completely precipitated, the pH of the leachate is adjusted to 4.03 using a 10 wt % liquid alkali, and then the reaction is continued at 70° C. for 1 hour. After the reaction is completed, the iron and aluminum precipitates and the valuable metal solution are obtained by suction filtration, thereby achieving the removal of iron and aluminum in the leachate of the ternary lithium-ion battery.

[0045] Example 3

[0046] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate, the method comprising the following steps:

[0047] (1) At 90°C, the ternary lithium-ion battery leachate is mixed with phosphoric acid for 1 hour to precipitate iron and aluminum in the leachate;

[0048] The ternary lithium-ion battery leachate includes 0.24 mol / L Ni ions, 0.08 mol / L Co ions, 0.08 mol / L Mn ions, 0.08 mol / L Cu ions, 0.12 mol / L Al ions and 0.08 mol / L Fe ions;

[0049] The molar amount of phosphoric acid added is 2.5 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, specifically 0.5 mol / L in the leachate;

[0050] (2) After the iron and aluminum in the leachate of step (1) are completely precipitated, the pH value of the leachate is adjusted to 2.5 using a 5 wt % liquid alkali, and then the reaction is continued at 90° C. for 0.5 h. After the reaction is completed, the iron and aluminum precipitates and the valuable metal solution are obtained by suction filtration, thereby achieving the removal of iron and aluminum in the leachate of the ternary lithium-ion battery.

[0051] Example 4

[0052] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method is the same as Example 1, except that the molar amount of phosphoric acid added is 1 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, specifically 0.2 mol / L in the leachate.

[0053] Example 5

[0054] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method is the same as Example 1, except that the molar amount of phosphoric acid added is 0.8 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, specifically 0.16 mol / L in the leachate.

[0055] Example 6

[0056] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method is the same as Example 1, except that the molar amount of phosphoric acid added is 3.5 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate, specifically 0.7 mol / L in the leachate.

[0057] Example 7

[0058] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method is the same as that of Embodiment 1 except that the pH of the leachate is adjusted to 2 in step (2).

[0059] Example 8

[0060] This embodiment provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method is the same as that of Embodiment 1 except that the pH of the leachate is adjusted to 4.8 in step (2).

[0061] Comparative Example 1

[0062] This comparative example provides a method for removing iron and aluminum from a ternary lithium-ion battery leachate. The method is the same as Example 1 except that step (2), i.e., the step of adjusting the pH of the leachate, is not performed.

[0063] The ion content in the solution obtained after removing iron and aluminum in the above embodiments and comparative examples was detected, and the precipitation rate of each ion was calculated. The precipitation rate calculation results are shown in Table 1:

[0064] Table 1

[0065]

[0066] From Table 1 we can see that:

[0067] It can be seen from Example 1 and Comparative Example 1 that the method of the present invention can efficiently remove iron and aluminum impurities without excessive loss of nickel, cobalt and manganese valuable metals, thereby achieving effective separation of impurity metals and valuable metals in the ternary lithium-ion battery leachate; It can be seen from Example 1 and Examples 4-6 that the present invention preferably adds an excess of phosphoric acid, but it is not easy to add too much phosphoric acid, and the preferred amount of phosphoric acid added is within a specific range; It can be seen from Example 1 and Examples 7-8 that the present invention preferably adjusts the pH within a specific range to ensure efficient removal of iron and aluminum while avoiding excessive loss of valuable metals.

[0068] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for removing iron and aluminum from a ternary lithium-ion battery leachate, characterized in that: The method comprises the following steps: (1) mixing the ternary lithium-ion battery leachate with phosphoric acid to precipitate iron and aluminum in the leachate; (2) After the iron and aluminum in the leachate of step (1) are precipitated, an alkaline substance is used to adjust the pH of the leachate, and then the reaction is continued to obtain an iron and aluminum precipitate and a valuable metal solution, thereby achieving the removal of iron and aluminum in the leachate of the ternary lithium-ion battery.

2. The method according to claim 1, characterized in that The molar amount of phosphoric acid added in step (1) is 1 to 2.5 times the total molar amount of iron and aluminum in the ternary lithium-ion battery leachate.

3. The method according to claim 1 or 2, characterized in that: The ternary lithium-ion battery leachate of step (1) includes 0.16-0.24 mol / L Ni ions, 0.08-0.12 mol / L Co ions, 0.08-0.12 mol / L Mn ions, 0.08-0.12 mol / L Cu ions, 0.08-0.12 mol / L Al ions and 0.08-0.12 mol / L Fe ions.

4. The method according to any one of claims 1 to 3, characterized in that: The mixing temperature in step (1) is 25 to 90° C. Preferably, the mixing time in step (1) is 1 to 2 hours.

5. The method according to any one of claims 1 to 4, characterized in that: In step (2), the pH of the leaching solution is adjusted to 2.5-4.

6. The method according to any one of claims 1 to 5, characterized in that: The pH regulator used in step (2) to adjust the pH of the leachate includes any one of lime milk, sodium hydroxide solution or potassium hydroxide solution or a combination of at least two of them, preferably a sodium hydroxide solution with a concentration of 5 to 15 wt%.

7. The method according to any one of claims 1 to 6, characterized in that: The reaction time in step (2) is 0.5 to 1 h; Preferably, the temperature for continuing the reaction in step (2) is 25 to 90°C.

8. The method according to any one of claims 1 to 7, characterized in that: After continuing the reaction in step (2), filtering is performed to obtain an iron-aluminum precipitate and a valuable metal solution.

9. The method according to any one of claims 1 to 8, characterized in that: After the continued reaction in step (2) is completed, the precipitation rate of Al is ≥99%; Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Fe is ≥99%.

10. The method according to any one of claims 1 to 9, characterized in that: After the continued reaction in step (2) is completed, the precipitation rate of Co is ≤10%; Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Ni is ≤9%; Preferably, after the continued reaction in step (2) is completed, the precipitation rate of Mn is ≤16%.

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