Method for self-adsorption separation and recycling of lithium-containing aluminum nitrate salt solution

Abstract

The present application belongs to the technical field of lithium nitrate solution aluminum-lithium separation, and specifically relates to a method for self-adsorption separation and recycling of aluminum nitrate solution containing trace lithium, which comprises the following steps: S1: treating lithium ore or nitric acid leaching solution containing lithium waste by using a nanofiltration membrane to obtain monovalent ion solution mainly containing lithium nitrate and non-mono-valent ion solution mainly containing aluminum nitrate; S2: using the monovalent ion solution obtained in S1 to prepare battery-grade lithium carbonate after purification and impurity removal; S3: adding magnesium oxide or magnesium carbonate to the non-mono-valent ion solution obtained in S1 to adjust the pH to 2-3.4, and the reaction temperature is 40-100 DEG C; S4: washing the Al(OH)3 precipitate obtained in S3 with water to obtain a mixture containing Li + solution and crude Al(OH)3; and subsequent treatment. The present application has the advantages of simple process, low processing cost, high lithium metal recovery rate, green and environmentally-friendly process, good economic benefits, and easy industrialization application.

Description

Technical Field

[0001] This invention relates to the chemical and metallurgical industry, specifically to the field of aluminum-lithium separation from lithium-containing nitrate solutions, and the efficient separation of aluminum and lithium to prepare battery-grade lithium carbonate. More specifically, it describes a method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium. Background Technology

[0002] Lithium, as an important energy metal, plays an irreplaceable role in the lithium battery industry and controlled thermonuclear reaction industry, and lithium salt products have long been closely related to national production and daily life. In recent years, with the vigorous promotion of lithium-ion power batteries in the automotive industry and the booming development of the energy storage industry, the global demand for lithium resources has grown rapidly.

[0003] Lithium resources are mainly distributed in granite pegmatite deposits and salt lake brines. Currently, there are relevant technologies for extracting and recovering lithium salts from these resources. The main production processes for pegmatite lithium deposits include sulfuric acid roasting, chloride roasting, limestone sintering, and pressure cooking. The main production processes for lithium extraction from salt lakes include extraction, precipitation, adsorption, calcination leaching, carbonization, and electrodialysis.

[0004] However, the above methods are insufficient to achieve highly selective separation of lithium and aluminum in high-aluminum content solutions, while simultaneously achieving a high lithium recovery rate. To improve lithium resource recovery and achieve efficient and comprehensive utilization of mineral resources, it is essential to develop a method for selectively recovering lithium resources from aluminum nitrate solutions. Summary of the Invention

[0005] To address the problem of low lithium recovery rates caused by the inefficient separation of lithium and aluminum in existing technologies, this invention provides a method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium. This method achieves high lithium recovery rates and enables the recycling of nitric acid and alkali (magnesium oxide).

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium includes the following steps:

[0008] S1: The nitric acid leachate from lithium ore or lithium-containing waste is treated with a nanofiltration membrane to obtain a monovalent ionic liquid mainly composed of lithium nitrate and a non-monovalent ionic liquid mainly composed of aluminum nitrate.

[0009] S2: The monovalent ionic liquid obtained from S1 is purified and impurities removed before being used to prepare battery-grade lithium carbonate;

[0010] S3: Add magnesium oxide or magnesium carbonate to the non-monovalent ionic liquid obtained in S1 to adjust the pH to 2-3.4. The reaction temperature is 40-100℃, preferably 40-80℃, so that some Al... 3+ It is converted into Al(OH)3 precipitate and adsorbs Li in the solution. + Ions were used to obtain Al(OH)3 precipitate and a mixed solution containing Al(NO3)3 and Mg(NO3)2, respectively.

[0011] S4: The Al(OH)3 precipitate obtained in S3 is washed with water to obtain Li-containing... + Solution and crude Al(OH)3, which contains Li + The monovalent ionic liquid obtained by returning the solution to S1 is then mixed.

[0012] S5: The mixture obtained in S3 is evaporated, concentrated, calcined and decomposed to obtain a solid mixture of Al2O3 and MgO and nitrogen oxide gas. The nitrogen oxide gas is used to prepare HNO3.

[0013] S6: The solid mixture of Al2O3 and MgO obtained in S5 is mixed with the crude Al(OH)3 obtained in step S4 and then treated with Bayer alkaline leaching to separate MgO and refined Al2O3 products.

[0014] Preferably, in S1, Li is a monovalent ionic liquid. + The content is 5-10 g / L, and the Li in the non-monovalent ionic liquid is + The content is 0-3g / L.

[0015] Preferably, in S1, the chemical composition of the nitric acid leachate includes: Li + 7.5-8.5 g / L, Al 3+ 5-6 g / L, Fe 3+ 0.5-0.6 g / L, Mn 2+ 0.2-0.4 g / L, Ca 2+ 0.5-0.6 g / L, K + 0.15-0.25 g / L, Na + 2-3g / L, H + 1-2 mol / L. For this specific chemical composition of the nitric acid leachate, it is more conducive to fully utilizing the self-adsorption effect of the subsequently formed suitable aluminum precipitate and lithium ions, while simultaneously improving the lithium recovery rate.

[0016] In S1 above, the chemical composition of the nitric acid leachate is simultaneously controlled, with Li in both monovalent and non-monovalent ionic solutions being controlled. + The appropriate content allows for the full utilization of the subsequent formation of suitable aluminum precipitates and the self-adsorption of lithium ions, thus improving the lithium recovery rate.

[0017] Preferably, in step S3, the pH is adjusted to 3-3.3, and the reaction temperature is 55-65℃. This preferred method facilitates the adsorption of as much lithium as possible from the aluminum nitrate solution into the aluminum hydroxide precipitate, thereby maximizing the lithium recovery rate.

[0018] Preferably, in step S3, the reaction time is 0.5-5 hours, more preferably 1-3 hours.

[0019] More preferably, in S3, the reaction time is 1-2 hours.

[0020] Preferably, in step S4, the water washing is a multi-stage water washing process, with 1-3 stages and a water washing temperature of 30-100℃.

[0021] More preferably, in step S4, the water washing employs a multi-stage washing process with three stages and a washing temperature of 60-70°C. This preferred method facilitates the separation of lithium and aluminum as much as possible, thereby maximizing the lithium recovery rate.

[0022] More preferably, in S4, the washing time for each stage is 0.5-4 hours, and even more preferably, the washing time is 1-2 hours.

[0023] Preferably, S6 further includes: returning the separated MgO to S3 for pH adjustment.

[0024] The beneficial effects of the present invention through the above technical solution are as follows:

[0025] This invention provides a method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium. By employing nanofiltration membrane treatment of the nitric acid leachate, combined with a self-adsorption separation step of aluminum and lithium under specific conditions (especially suitable pH and temperature), and subsequent water washing, the recovery rate of lithium in the lithium-containing aluminum nitric acid leachate can be effectively improved. This method achieves efficient separation and high lithium recovery from non-monovalent ionic liquids separated by nanofiltration membranes, while simultaneously enabling the recycling of nitric acid and magnesium oxide. Under the same conditions, if the pH and temperature in the aluminum and lithium self-adsorption separation step are too high, more magnesium oxide and energy will be consumed, resulting in a higher magnesium ion concentration in the magnesium nitrate solution obtained during washing; if they are too low, the lithium ions in the solution will not be completely adsorbed, resulting in a low recovery rate; and low temperature will lead to difficulties in filtering the feed solution.

[0026] This invention features a simple process, low auxiliary material consumption, low processing cost, and high lithium metal recovery rate. This process not only achieves efficient recycling of lithium resources but also aluminum resources. The added nitric acid and alkali (magnesium oxide) can be recycled. The entire process has low auxiliary material consumption, high lithium metal recovery rate, resource recycling, is green and environmentally friendly, has good economic benefits, and is easy to industrialize. Detailed Implementation

[0027] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] The technical solution of the present invention will be described in further detail and completely below with reference to the embodiments.

[0029] The partial composition of the spodumene nitric acid leaching solution used in the examples is shown in Table 1.

[0030] Table 1

[0031]

[0032] Example 1

[0033] A method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium, specifically comprising:

[0034] Step 1: The nitric acid leaching solution of spodumene is treated with a nanofiltration membrane to obtain a monovalent ionic liquid with a lithium content of 8 g / L and a non-monovalent ionic liquid with a lithium content of 0.5 g / L (hereinafter referred to as aluminum nitrate solution);

[0035] Step 2: The monovalent ionic liquid obtained in step S1 is used to prepare battery-grade lithium carbonate after impurity removal;

[0036] Step 3: Add MgO to the aluminum nitrate solution obtained in step S1 to adjust the pH to 2.5. The reaction temperature is 50℃, and the reaction time is 1 hour, so that some Al... 3+ It is converted into Al(OH)3 precipitate and adsorbs Li in the solution. + Ions were used to obtain small amounts of Al(OH)3 precipitate and mixed solutions of Al(NO3)3 and Mg(NO3)2, respectively.

[0037] Step 4: The Al(OH)3 precipitate obtained in step S3 is stirred and washed three times with water at 50℃, with each washing time lasting 1.5 hours, to obtain Li-containing... + Solution and crude Al(OH)3, which contains Li + The solution is returned to the monovalent ionic liquid obtained in step S1 for mixing and processing;

[0038] Step 5: The Al(NO3)3 and Mg(NO3)2 mixture obtained in step S3 is evaporated, concentrated, calcined, and decomposed to obtain a mixture of Al2O3 and MgO with NO. X Gas, producing NO XUsed to prepare HNO3;

[0039] Step 6: The solid mixture of Al2O3 and MgO obtained in step S5 and the crude Al(OH)3 obtained in step S4 are both treated with Bayer alkaline leaching to separate MgO and refined Al2O3. The MgO is returned to step S3 to adjust the pH.

[0040] In Example 1, the lithium metal recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution accounted for 30.1% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal recovered from the precipitation and washing of aluminum hydroxide was 91.4%.

[0041] Example 2

[0042] A method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium is implemented according to the method described in Example 1, with the following difference:

[0043] In step 3, MgO is used to adjust the pH to 3, and the reaction temperature is 60℃.

[0044] Step 4: The Al(OH)3 precipitate is stirred and washed three times with water under a 60°C water bath heating condition.

[0045] In Example 2, lithium metal recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution accounted for 71% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal recovered from the precipitation and washing of aluminum hydroxide was 92.8%.

[0046] Example 3

[0047] A method for the self-adsorption separation and recycling of aluminum nitrate solutions containing trace amounts of lithium is implemented according to the method described in Example 1, with the difference being:

[0048] In step 3, MgO is used to adjust the pH to 3.3, and the reaction temperature is 70°C.

[0049] Step 4: The Al(OH)3 precipitate is stirred and washed twice with water under 80°C water bath heating conditions;

[0050] In Example 3, lithium resources were recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution, accounting for 98% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal from washing with aluminum hydroxide was 93.6%.

[0051] Example 4

[0052] A method for the self-adsorption separation and recycling of aluminum nitrate solution containing trace amounts of lithium is implemented according to the method described in Example 2, except that in step 3, MgO is used to adjust the pH to 3.3.

[0053] In this embodiment, lithium resources recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution accounted for 97.3% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal recovered from washing with aluminum hydroxide was 93.1%.

[0054] Example 5

[0055] A method for the self-adsorption separation and recycling of aluminum nitrate solution containing trace amounts of lithium is implemented according to the method described in Example 2, except that the reaction temperature in step 3 is 40°C.

[0056] In this embodiment, lithium resources recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution accounted for 71.5% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal recovered from washing with aluminum hydroxide was 88.2%.

[0057] Example 6

[0058] A method for self-adsorption separation and recycling of aluminum nitrate solution containing trace amounts of lithium is implemented according to the method described in Example 2, except that: step 4: Al(OH)3 precipitate is stirred and washed three times with water under water bath heating at 80°C.

[0059] In this embodiment, 70.1% of the total lithium in the non-monovalent ionic liquid was recovered from aluminum hydroxide precipitation in aluminum nitrate solution, and the recovery rate of lithium metal from washing in aluminum hydroxide was 93.8%.

[0060] Example 7

[0061] A method for the self-adsorption separation and recycling of aluminum nitrate solution containing trace amounts of lithium is implemented according to the method described in Example 2, except that the reaction temperature in step 3 is 100°C.

[0062] In this embodiment, lithium resources recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution accounted for 70% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal recovered from washing with aluminum hydroxide was 94%.

[0063] Comparative Example 1

[0064] A method for the self-adsorption separation and recycling of aluminum nitrate solution containing trace amounts of lithium is implemented according to the method described in Example 2, except that in step 3, MgO is used to adjust the pH to 1.5.

[0065] In this embodiment, lithium resources recovered from the precipitation of aluminum hydroxide from aluminum nitrate solution accounted for 15% of the total lithium in the non-monovalent ionic liquid, and the recovery rate of lithium metal recovered from washing with aluminum hydroxide was 21%.

[0066] The above description is only a partial embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for the self-adsorption separation and recycling of aluminum nitrate solution containing trace amounts of lithium, characterized in that, Includes the following steps: S1: The nitric acid leachate from lithium ore or lithium-containing waste is treated with a nanofiltration membrane to obtain a monovalent ionic liquid mainly composed of lithium nitrate and a non-monovalent ionic liquid mainly composed of aluminum nitrate. In S1, the chemical composition of the nitric acid leachate includes: Li + 7.5-8.5 g / L, Al 3+ 5-6 g / L, Fe 3+ 0.5-0.6 g / L, Mn 2+ 0.2-0.4 g / L, Ca 2+ 0.5-0.6 g / L, K + 0.15-0.25 g / L, Na + 2-3g / L, H + 1-2mol / L; S2: The monovalent ionic liquid obtained from S1 is purified and impurities removed before being used to prepare battery-grade lithium carbonate; S3: Add magnesium oxide or magnesium carbonate to the non-monovalent ionic liquid obtained in S1 to adjust the pH to 3.

3. The reaction temperature is 55-65℃, so that some Al... 3+ It is converted into Al(OH)3 precipitate and adsorbs Li in the solution. + Ions were used to obtain Al(OH)3 precipitate and a mixed solution containing Al(NO3)3 and Mg(NO3)2, respectively. S4: The Al(OH)3 precipitate obtained in S3 is washed with water in a multi-stage washing process, with three washing stages at a temperature of 60-70℃, to obtain Li-containing... + The solution is mixed with crude Al(OH)3, in which the Li+-containing solution is returned to S1 to obtain a monovalent ionic liquid; S5: The mixture obtained in S3 is evaporated, concentrated, calcined and decomposed to obtain a solid mixture of Al2O3 and MgO and nitrogen oxide gas. The nitrogen oxide gas is used to prepare HNO3. S6: The solid mixture of Al2O3 and MgO obtained in S5 is mixed with the crude Al(OH)3 obtained in step S4 and then treated with Bayer alkaline leaching to separate MgO and refined Al2O3 products. The separated MgO is returned to S3 for pH adjustment.

2. The method according to claim 1, characterized in that, In S1, Li in monovalent ionic liquid + The content is 5-10 g / L, and the Li in the non-monovalent ionic liquid is + The content is 0-3 g / L and Li + The content is not 0.

3. The method according to claim 1, characterized in that, In S3, the reaction time is 0.5-5 hours.

4. The method according to claim 3, characterized in that, In S3, the reaction time is 1-3 hours.

5. The method according to claim 1, characterized in that, In S4, the washing time for each stage is 0.5-4 hours.

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