Method for comprehensively recycling waste lithium manganate positive electrode material

Abstract

The invention discloses a method for comprehensively recycling a waste lithium manganate positive electrode material, which comprises the following steps: by taking the waste lithium manganate positive electrode material as a raw material, leaching with sulfuric acid to obtain a mixed solution of manganese sulfate and lithium sulfate, and adding caustic soda flakes to adjust the pH value to obtain a purified solution; adding sodium carbonate into the purified liquid to obtain manganese carbonate and lithium sulfate solution; adding trisodium phosphate into the lithium sulfate solution to obtain lithium phosphate and sodium sulfate mother liquor; a manganese adsorbent is added into the mother liquor for lithium adsorption, and an adsorbed product is LiMn2O4 and can be returned to leaching of lithium manganate. According to the method, the lithium salt and the valuable metal can be recycled from the waste lithium manganate positive electrode material, the valuable metal recycling efficiency is high, the manganese-lithium comprehensive recycling rate is larger than 95%, the adsorption capacity of the manganese adsorbent is high and can reach 8 mg / g or above on average, and efficient comprehensive utilization of the waste lithium manganate positive electrode material is achieved.

Description

Technical Field

[0001] The invention belongs to the field of recycling waste lithium manganese oxide positive electrode materials, and in particular relates to a method for comprehensive recycling of waste lithium manganese oxide positive electrode materials. Background Art

[0002] Lithium manganese oxide is one of the most promising lithium-ion cathode materials. Compared with traditional cathode materials such as lithium cobalt oxide, lithium manganese oxide has the advantages of abundant resources, low cost, no pollution, good safety, and good rate performance. It is an ideal cathode material for power batteries. With the rapid development of the new energy vehicle industry, the production and sales of lithium manganese oxide batteries have also been greatly improved. Of course, the problem of handling waste lithium manganese oxide materials comes with it. As a rich and cheap metal, manganese is affected by the value of manganese. The current lithium manganese oxide recovery technology is only aimed at the extraction of lithium, and there are still high difficulties in indicators such as economy.

[0003] In view of this, the present invention uses sulfuric acid to leach waste lithium manganese oxide positive electrode materials to obtain a mixed solution of manganese adsorbent and lithium sulfate and manganese sulfate. Manganese sulfate is made into manganese carbonate and lithium sulfate is made into lithium phosphate. The manganese adsorbent is used to extract deep lithium from low-lithium content lithium precipitation mother liquor or lithium brine in salt lakes, thereby realizing highly economical recovery of waste lithium manganese oxide positive electrode materials. Summary of the invention

[0004] The purpose of the present invention is to provide a method for comprehensive recycling of waste lithium manganese oxide positive electrode materials in view of the defects of the prior art.

[0005] Specifically, a method for comprehensive recycling of waste lithium manganese oxide positive electrode materials of the present invention comprises the following steps:

[0006] (1) Take 100 kg of waste lithium manganate positive electrode material, add 800-1100 L of 3-8% sulfuric acid solution, stir and leach at 30-50 ° C for 2-5 hours, filter, and wash with pure water to obtain manganese adsorbent HMn 2 O 4 and filtrate for later use;

[0007] (2) taking the filtrate and adding 18-25 kg of caustic soda flakes to adjust the pH to 5-6 to obtain a purified solution;

[0008] (3) adding 15-25 kg of sodium carbonate to the purified liquid to adjust the pH to 7-9, stirring at 70-90° C. to synthesize manganese carbonate, filtering, and washing with pure water to obtain a solid manganese carbonate product and a lithium sulfate solution;

[0009] (4) adding 40-70 kg of trisodium phosphate to a lithium sulfate solution, controlling the temperature to 90° C., filtering, and washing with pure water to obtain a lithium phosphate and sodium sulfate mother liquor;

[0010] (5) Taking the sodium sulfate mother liquor, using 3-5 kg ​​of concentrated sulfuric acid to adjust the pH value to 8-9, then adding 30-40 kg of manganese adsorbent, stirring and adsorbing at a temperature of 40-60° C. for 1-3 hours to adsorb the residual lithium in the sodium sulfate mother liquor, filtering, washing and separating with pure water to finally obtain lithium manganate and sodium sulfate solution, and returning the lithium manganate to step (1) for recycling.

[0011] In the step (1), 100 kg of waste lithium manganate positive electrode material is added to 900-1000 L of 5-8% sulfuric acid solution, stirred and leached at 40-50° C. for 2-3 h, filtered, and washed with pure water to obtain a manganese adsorbent HMn 2 O 4 And filtrate, set aside.

[0012] In the step (2), 20-23 kg of caustic soda flakes are added to adjust the pH value to 5-6 to remove a small amount of titanium, iron and aluminum elements in the solution.

[0013] In the step (3), 19-24 kg of sodium carbonate is added to the purified liquid to adjust the pH to 7-9, and the mixture is stirred at 80-90° C. to synthesize manganese carbonate. After filtering, the mixture is washed with pure water to obtain a solid manganese carbonate product and a lithium sulfate solution.

[0014] In the step (3), 19-24 kg of sodium carbonate is added to the purified liquid to adjust the pH to 7.5-8.5 to prevent the precipitation of manganese hydroxide due to excessively high pH.

[0015] In the step (4), 55-70 kg of trisodium phosphate is added to the lithium sulfate solution, the temperature is controlled at 90° C., and after filtering, the solution is washed with pure water to obtain lithium phosphate and sodium sulfate mother liquor.

[0016] In the step (5), the sodium sulfate mother liquor is taken and adjusted to a pH value of 8-9 using 3-4 kg of sulfuric acid, and then 34-40 kg of manganese adsorbent is added, and the mixture is stirred and adsorbed at a temperature of 40-50° C. for 2-3 hours to adsorb the residual lithium in the sodium sulfate mother liquor. After filtering, the mixture is washed and separated with pure water to finally obtain lithium manganate and sodium sulfate solution. The lithium manganate can be returned to step (1) for recycling.

[0017] The technical solution of the present invention has the following beneficial effects:

[0018] (1) In the present invention, in the process of leaching waste lithium manganese oxide positive electrode materials, a small amount of titanium, iron and aluminum elements in the solution are removed in the form of a combination of inorganic acids and caustic soda to adjust the pH value. Iron and aluminum are mainly removed in the form of hydroxides, and titanium is mainly removed in the form of titanium dioxide, thereby improving the leaching recovery effect of valuable metals and obtaining solid manganese carbonate products and lithium phosphate products.

[0019] (2) The waste lithium manganese oxide positive electrode material of the present invention is leached with sulfuric acid to obtain a manganese adsorbent, which is used to perform secondary adsorption of the residual lithium in the sodium sulfate mother liquor. The obtained lithium manganese oxide can be recycled again, realizing the recycling of the leached raw materials, further reducing the recovery cost of waste lithium iron phosphate battery positive electrode materials. The manganese adsorbent has a high adsorption capacity, which can reach an average of more than 8 mg / g, and is economical and less expensive than traditional manganese-based adsorbents and titanium-based adsorbents.

[0020] (3) Compared with the traditional recovery method of complete acid leaching, the present invention does not adopt complete leaching, but adopts semi-leaching. The waste residue from the semi-leaching can be used as an adsorbent for the adsorption of lithium-containing mother liquor. Finally, manganese can also be produced as manganese salt. Compared with traditional recovery, it can realize the recycling of resources and has a higher circular economy.

[0021] (4) The method of the present invention can recover lithium salts and valuable metals from waste lithium manganese oxide positive electrode materials, with high valuable metal recovery efficiency and a comprehensive recovery rate of manganese and lithium greater than 95%, thus achieving comprehensive recovery of waste lithium manganese oxide positive electrode materials;

[0022] (5) The recycling method provided by the present invention is simple to operate, has no special requirements for the production process, is environmentally friendly, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The present invention is further described below in conjunction with examples. The examples are only further supplements and explanations of the present invention, rather than limitations of the invention.

[0025] Embodiment 1:

[0026] (1) Prepare 900 L of 5% sulfuric acid solution, weigh 100 kg of waste lithium manganate positive electrode material, with a manganese content of 52.5% and a lithium content of 3.58%, add sulfuric acid solution and stir to leach at 45°C for 3 h, filter, wash with pure water and separate to obtain manganese adsorbent (HMn 2 O 4 ) 82 kg and a filtrate, wherein the lithium content of the manganese adsorbent is 0.45%, the lithium concentration of the filtrate is 3.6 g / L, the manganese concentration is 11 g / L, and the pH is 1.5;

[0027] (2) taking the filtrate and adding 20 kg of caustic soda flakes to adjust the pH to 6, filtering to remove insoluble matter, and obtaining a purified solution;

[0028] (3) adding 19 kg of sodium carbonate to the purified liquid, controlling the temperature at 80° C., filtering, washing with pure water to separate and obtain 18.2 kg of manganese carbonate and a lithium sulfate solution with a lithium concentration of 3.2 g / L, and controlling the pH at 7.5-8.5;

[0029] (4) adding 55.8 kg of trisodium phosphate to a lithium sulfate solution, controlling the temperature to 90° C., filtering, and washing with pure water to separate 16.5 kg of lithium phosphate and sodium sulfate mother liquor, wherein the lithium concentration of the sodium sulfate mother liquor is 0.35 g / L;

[0030] (5) Add 3.2 kg of concentrated sulfuric acid to the sodium sulfate mother liquor to adjust the pH to 8-9, then add 34 kg of manganese adsorbent, stir and adsorb at 50° C. for 2 h to adsorb the residual lithium in the sodium sulfate mother liquor, filter, wash and separate with pure water to finally obtain lithium manganate and sodium sulfate solution.

[0031] The lithium content of the sodium sulfate filtrate was detected to be 0.025 g / L, the filter cake (lithium manganate) was 38.2 kg, the lithium content was 1.18%, and the adsorption efficiency was calculated to be 8.6 mg / g.

[0032] Embodiment 2:

[0033] (1) Prepare 1000 L of 6% sulfuric acid solution, weigh 100 kg of waste lithium manganese oxide positive electrode material, with a manganese content of 52.5% and a lithium content of 3.58%, weigh 35 kg of the adsorption filter cake (lithium manganese oxide) in Example 1, add it to the sulfuric acid solution, stir and leach it at 50° C. for 2 h, filter it, wash it with pure water, and separate it to obtain a manganese adsorbent (HMn 2 O 4 ) 105 kg and a filtrate, wherein the lithium content of the manganese adsorbent is 0.36%, the lithium concentration of the filtrate is 3.58 g / L, the manganese concentration is 12.5 g / L, and the pH is 1.2;

[0034] (2) taking the filtrate and adding 23 kg of caustic soda flakes to adjust the pH to 5.6, filtering to remove insoluble matter, and obtaining a purified solution;

[0035] (3) adding 23.5 kg of sodium carbonate to the purified liquid, controlling the temperature at 85° C., filtering, washing with pure water to separate and obtain 22.52 kg of manganese carbonate and a lithium sulfate solution with a lithium concentration of 3.15 g / L, and controlling the pH at 7.5-8.5;

[0036] (4) adding 66.5 kg of trisodium phosphate to a lithium sulfate solution, controlling the temperature to 90° C., filtering, and washing with pure water to separate and obtain 19.8 kg of lithium phosphate and sodium sulfate mother liquor, wherein the lithium concentration of the sodium sulfate mother liquor is 0.32 g / L;

[0037] (5) Take the lithium precipitation mother liquor and add 3.7 kg of concentrated sulfuric acid to adjust the pH to 8-9, add 37 kg of manganese adsorbent, stir and adsorb at 45° C. for 3 hours to adsorb the residual lithium in the sodium sulfate mother liquor, filter, wash and separate with pure water to finally obtain lithium manganate and sodium sulfate solution.

[0038] The lithium content of the sodium sulfate filtrate was detected to be 0.015 g / L, and the adsorption efficiency was calculated to be 8.25 mg / g.

[0039] Embodiment 3:

[0040] The recovered manganese adsorbent was applied to lithium extraction from salt lakes: 1000L of lithium-containing brine from the salt lake with a lithium concentration of 0.22g / L was taken, the pH was adjusted to 8-9 with concentrated sulfuric acid, 25.8kg of the manganese adsorbent of the above embodiment was added, and the mixture was stirred and adsorbed at 45°C for 3h. After filtering, the mixture was washed and separated with pure water. The lithium concentration of the filtrate was 0.012g / L and the adsorption efficiency was 8.06mg / g by detecting the filtrate.

[0041] Table 1 Adsorption efficiency test results of the embodiment

[0042]

[0043]

[0044] According to Table 1, the manganese adsorbent has a high adsorption capacity, which can reach an average of more than 8 mg / g. In the present invention, the manganese adsorbent and the adsorbed product lithium manganate are returned to the system for recycling, which can achieve the recycling of resources, reduce environmental pollution, and have high circular economy.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for comprehensive recycling of waste lithium manganese oxide positive electrode materials, characterized in that: The method for comprehensive recycling of waste lithium manganese oxide positive electrode materials comprises the following steps: (1) taking 100 kg of waste lithium manganese oxide positive electrode material, adding 800-1100 L of 3-8% sulfuric acid solution, stirring and leaching at 30-50° C. for 2-5 h, filtering, washing with pure water to obtain a manganese adsorbent HMn2O4 and a filtrate, and setting aside; (2) taking the filtrate and adding 18-25 kg of caustic soda flakes to adjust the pH to 5-6 to obtain a purified solution; (3) adding 15-25 kg of sodium carbonate to the purified liquid to adjust the pH to 7-9, stirring at 70-90° C. to synthesize manganese carbonate, filtering, and washing with pure water to obtain a solid manganese carbonate product and a lithium sulfate solution; (4) adding 40-70 kg of trisodium phosphate to a lithium sulfate solution, controlling the temperature to 90° C., filtering, and washing with pure water to obtain a lithium phosphate and sodium sulfate mother liquor; (5) Taking the sodium sulfate mother liquor, using 3-5 kg ​​of concentrated sulfuric acid to adjust the pH value to 8-9, then adding 30-40 kg of manganese adsorbent, stirring and adsorbing at a temperature of 40-60° C. for 1-3 hours to adsorb the residual lithium in the sodium sulfate mother liquor, filtering, washing and separating with pure water to finally obtain lithium manganate and sodium sulfate solution, and returning the lithium manganate to step (1) for recycling.

2. The method for comprehensive recycling of waste lithium manganese oxide positive electrode materials as claimed in claim 1, characterized in that: In the step (1), 100 kg of waste lithium manganate positive electrode material is added with 900-1000 L of 5-8% sulfuric acid solution, stirred and leached at 40-50° C. for 2-3 hours, filtered, and washed with pure water to obtain a manganese adsorbent HMn2O4 and a filtrate for standby use.

3. The method for comprehensive recycling of waste lithium manganese oxide positive electrode materials as claimed in claim 1, characterized in that: In the step (2), 20-23 kg of caustic soda flakes are added to adjust the pH value to 5-6 to remove a small amount of titanium, iron and aluminum elements in the solution.

4. The method for synthesizing the spherical lithium manganese iron phosphate positive electrode material according to claim 1, characterized in that: In the step (3), 19-24 kg of sodium carbonate is added to the purified liquid to adjust the pH to 7-9, and the mixture is stirred at 80-90° C. to synthesize manganese carbonate. After filtering, the mixture is washed with pure water to obtain a solid manganese carbonate product and a lithium sulfate solution.

5. The method for comprehensive recycling of waste lithium manganese oxide positive electrode materials as claimed in claim 1, characterized in that: In the step (3), 19-24 kg of sodium carbonate is added to the purified liquid to adjust the pH to 7.5-8.5 to prevent the precipitation of manganese hydroxide due to excessively high pH.

6. The method for comprehensive recycling of waste lithium manganese oxide positive electrode materials as claimed in claim 1, characterized in that: In the step (4), 55-70 kg of trisodium phosphate is added to the lithium sulfate solution, the temperature is controlled at 90° C., and after filtering, the solution is washed with pure water to obtain lithium phosphate and sodium sulfate mother liquor.

7. The method for synthesizing the spherical lithium manganese iron phosphate positive electrode material according to claim 1, characterized in that: In the step (5), the sodium sulfate mother liquor is taken and adjusted to a pH value of 8-9 using 3-4 kg of sulfuric acid, and then 34-40 kg of manganese adsorbent is added, and the mixture is stirred and adsorbed at a temperature of 40-50° C. for 2-3 hours to adsorb the residual lithium in the sodium sulfate mother liquor. After filtering, the mixture is washed and separated with pure water to finally obtain lithium manganate and sodium sulfate solution. The lithium manganate can be returned to step (1) for recycling.

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