METHOD FOR RECYCLING LITHIUM IRON PHOSPHATE WASTE AND APPLICATION THEREOF

Abstract

The present disclosure discloses a method for recycling lithium iron phosphate waste and its application. The method comprises the following steps: disassembling, crushing, and sieving the lithium iron phosphate waste to obtain a lithium iron phosphate powder; Diluting a ionic membrane liquid alkali, adding the lithium iron phosphate powder to the alkali, stirring under an oxidizing atmosphere in water bath to perform a reaction; filtering a resulting product to obtain a leachate and a lithium phosphate slag; drying the lithium phosphate slag, adding an ammonia aqueous solution to the slag to perform a reaction, filtering to obtain an ammonia aqueous solution containing lithium phosphate and a filter residue; the ammonia aqueous solution containing lithium phosphate is evaporated to obtain lithium phosphate. By adopting the present method of removing aluminum by alkaline leaching under an oxidizing atmosphere, the aluminum content in the obtained lithium iron phosphate slag is 0.08%.

Claims

1. A method for recycling lithium iron phosphate waste, comprising the following steps: (1) subjecting the lithium iron phosphate waste to dissembling, crushing and screening to obtain a lithium iron phosphate powder; (2) adding an ionic membrane liquid alkali to the lithium iron phosphate powder and stirring and introducing air to perform a reaction in a water bath, filtering to obtain a leachate and a lithium phosphate slag; (3) drying the lithium phosphate slag before adding it to an ammonia aqueous solution and stirring to perform a reaction, filtering to obtain a filter slag and an ammonia solution containing lithium phosphate; wherein step (3) further comprises subjecting the filter slag to a magnetic separation to obtain Fe.sub.3O.sub.4. (4) evaporating the ammonia solution containing lithium phosphate to obtain lithium phosphate.

2. The method according to claim 1, wherein in step (2), the ionic membrane liquid alkali is first diluted and then added to the lithium iron phosphate powder and stirred, then air is introduced to allow the reaction in the water batch, and then filtration is conducted to obtain the leachate and the lithium phosphate slag; the ionic membrane liquid alkali has a mass concentration of 30% and is diluted to a mass concentration of 3%-10%.

3. The method according to claim 1, wherein in step (2), the lithium iron phosphate powder and the ionic membrane liquid alkali have a mass-to-volume ratio of 1:(4-10).

4. The method according to claim 1, wherein in step (2), the reaction in the water bath is carried out at 60° C.-90° C.; wherein in step (2), the reaction in the water bath is carried out for 0.5-2 h.

5. The method according to claim 1, wherein in step (3), the reaction is carried out in a nitrogen atmosphere or argon atmosphere at 30° C.-38° C. for 40-80 min.

6. The method according to claim 1, wherein in step (3), the ammonia aqueous solution has a mass concentration of 8-10%.

7. The method according to claim 1, wherein in step (3), the stirring is carried out at a rotational speed of 300-500 r/min.

8. A battery recycling method, comprising using the method of claim 1.

9. A battery recycling method, comprising using the method of claim 2.

10. A battery recycling method, comprising using the method of claim 3.

11. A battery recycling method, comprising using the method of claim 4.

12. A battery recycling method, comprising using the method of claim 5.

13. A battery recycling method, comprising using the method of claim 6.

14. A battery recycling method, comprising using the method of claim 7.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0035] The sole FIGURE is a process flow diagram of Example 1 of the present disclosure.

DETAILED DESCRIPTION OF THE ILLUSTRATED EXAMPLES

[0036] In order to fully understand the present disclosure, the preferred experimental scheme of the present disclosure will be described below in conjunction with examples to further illustrate the characteristics and advantages of the present disclosure. Any change or alteration that does not deviate from the gist of the present disclosure can be understood by those skilled in the art. The scope of protection of the present disclosure is determined by the scope of the claims.

[0037] Where specific conditions are not indicated in the examples of the present disclosure, it shall be carried out under the conventional conditions or the conditions recommended by the manufacturer. The raw materials, reagents, etc. used without indicating their manufacturers are all conventional products commercially available.

EXAMPLE 1

[0038] The recycling method of a lithium iron phosphate waste of this embodiment comprises the following steps:

[0039] (1) Disassembling, crush and screening the lithium iron phosphate waste to obtain a lithium iron phosphate powder;

[0040] (2) Weighing 500 g of the lithium iron phosphate powder with a mass fraction of 67.7%, preparing 3000 ml of a NaOH solution with a mass fraction of 10%, and mixing the powder with the NaOH solution to obtain a lithium iron phosphate slurry;

[0041] (3) Placing the slurry obtained in step (2) in a constant temperature water bath at a temperature of 80° C. and introducing air to perform a reaction for 120 min, and filtering to obtain 2887 ml of an alkaline solution containing sodium metaaluminate and sodium phosphate, and 409.2 of a slag containing lithium phosphate, carbon powder and ferroferric oxide;

[0042] (4) Weighing 300 g of the slag of step (3) containing lithium phosphate, carbon powder and ferroferric oxide, preparing 2400 ml of an ammonia aqueous solution of a mass fraction of 10%, and mixing the slag with the ammonia aqueous solution in a nitrogen atmosphere to obtain a lithium phosphate slurry;

[0043] (5) Placing the slurry obtained in step (4) at room temperature for 60 min to perform a reaction, and filtering to obtain 2355 ml of an ammonia aqueous solution containing lithium phosphate, and 237.8 g of a slag containing ferroferric oxide and carbon powder;

[0044] (6) Evaporating the ammonia aqueous solution containing lithium phosphate of step (5) to obtain 58.8 g of pure lithium phosphate product.

[0045] The sole FIGURE is a process flow diagram of Example 1 of the present disclosure. From the sole FIGURE, it can be seen that the pretreated lithium iron phosphate waste is crushed and screened to obtain a lithium iron phosphate powder; it is mixed with a prepared sodium hydroxide solution to obtain a slurry. The slurry is subjected to a period of reaction under a certain temperature, stirring rate and oxidizing atmosphere, and then filtered to obtain a lithium phosphate slag and a leachate containing AlO.sub.2.sup.−, PO.sub.4.sup.3−, Na.sup.+, etc. Mix the lithium phosphate slag with a prepared ammonia aqueous solution of suitable concentration, adjust the solid-liquid ratio and perform a reaction in a protective atmosphere to obtain an aqueous ammonia solution containing lithium phosphate and a slag material containing Fe.sub.3O.sub.4, Cu, C and other components. The ammonia aqueous solution containing lithium phosphate is evaporated to obtain a pure lithium phosphate product; and the slag material is subjected to a magnetic separation process to obtain pure Fe.sub.3O.sub.4.

EXAMPLE 2

[0046] The recycling method of a lithium iron phosphate waste of this embodiment comprises the following steps:

[0047] (1) Disassembling, crush and screening the lithium iron phosphate waste to obtain a lithium iron phosphate powder;

[0048] (2) Weighing 500 g of the lithium iron phosphate powder with a mass fraction of 67.7%, preparing 3000 mol of a NaOH solution with a mass fraction of 12%, and mixing the powder with the NaOH solution to obtain a lithium iron phosphate slurry;

[0049] (3) Placing the slurry obtained in step (2) in a constant temperature water bath at a temperature of 80° C. and introducing air to perform a reaction for 120 min, and filtering to obtain 2905 ml of an alkaline solution containing sodium metaaluminate and sodium phosphate, and 408.8 of a slag containing lithium phosphate, carbon powder and ferroferric oxide;

[0050] (4) Weighing 300 g of the slag of step (3) containing lithium phosphate, carbon powder and ferroferric oxide, preparing 2400 ml of an ammonia aqueous solution of a mass fraction of 8%, and mixing the slag with the ammonia aqueous solution in a nitrogen atmosphere to obtain a lithium phosphate slurry;

[0051] (5) Placing the slurry obtained in step (4) at room temperature for 60 min to perform a reaction, and filtering to obtain 2362 ml of an ammonia aqueous solution containing lithium phosphate, and 238.2 g of a slag containing ferroferric oxide and carbon powder;

[0052] (6) Evaporating the ammonia aqueous solution containing lithium phosphate of step (5) to obtain 57.9 g of pure lithium phosphate product.

EXAMPLE 3

[0053] The recycling method of a lithium iron phosphate waste of this embodiment comprises the following steps:

[0054] (1) Disassembling, crush and screening the lithium iron phosphate waste to obtain a lithium iron phosphate powder;

[0055] (2) Weighing 500 g of the lithium iron phosphate powder with a mass fraction of 67.7%, preparing 2500 ml of a NaOH solution with a mass fraction of 5%, and mixing the powder with the NaOH solution to obtain a lithium iron phosphate slurry;

[0056] (3) Placing the slurry obtained in step (2) in a constant temperature water bath at a temperature of 80° C. and introducing air to perform a reaction for 90 min, and filtering to obtain 2412 ml of an alkaline solution containing sodium metaaluminate, and 473.1 of a slag containing lithium phosphate, carbon powder;

[0057] (4) Diluting the alkaline solution of step (3) and melting the slag to test the leaching rates. Leaching rates of aluminum, phosphorus and lithium are 70.8%, 2.47%, 2.82% respectively.

EXAMPLE 4

[0058] The recycling method of a lithium iron phosphate waste of this embodiment comprises the following steps:

[0059] (1) Disassembling, crush and screening the lithium iron phosphate waste to obtain a lithium iron phosphate powder;

[0060] (2) Weighing 500 g of the lithium iron phosphate powder with a mass fraction of 67.7%, preparing 2500 mol of a NaOH solution with a mass fraction of 6%, and mixing the powder with the NaOH solution to obtain a lithium iron phosphate slurry;

[0061] (3) Placing the slurry obtained in step (2) in a constant temperature water bath at a temperature of 80° C. and introducing air to perform a reaction for 90 min, and filtering to obtain 2406 ml of an alkaline solution containing sodium metaaluminate, and 466.9 of a slag containing lithium phosphate, carbon powder;

[0062] (4) Diluting the alkaline solution of step (3) and melting the slag to test the leaching rates. Leaching rates of aluminum, phosphorus and lithium are 70.5%, 2.93%, 3.21% respectively.

EXAMPLE 5

[0063] The recycling method of a lithium iron phosphate waste of this embodiment comprises the following steps:

[0064] (1) Disassembling, crush and screening the lithium iron phosphate waste to obtain a lithium iron phosphate powder;

[0065] (2) Weighing 500 g of the lithium iron phosphate powder with a mass fraction of 67.7%, preparing 2500 ml of a NaOH solution with a mass fraction of 5%, and mixing the powder with the NaOH solution to obtain a lithium iron phosphate slurry;

[0066] (3) Placing the slurry obtained in step (2) in a constant temperature water bath at a temperature of 80° C. and introducing air to perform a reaction for 120 min, and filtering to obtain 2395 ml of an alkaline solution containing sodium metaaluminate, and 468.3 of a slag containing lithium phosphate, carbon powder;

[0067] (4) Diluting the alkaline solution of step (3) and melting the slag to test the leaching rates. Leaching rates of aluminum, phosphorus and lithium are 71.5%, 2.74%, 3.08% respectively.

TABLE-US-00001 TABLE 1 Materials and cost of Example 1 30% ionic 20% ammonia membrane aqueous Materials alkaline solution Nitrogen Total Additive 1.55 2.4 0.5 amount/m.sup.3 Price/RMB 1152 1223 12 2387

TABLE-US-00002 TABLE 2 Contents of the lithium phosphate obtained in Example 1 major component Item content Ni/ppm Co/ppm Mn/ppm Ca/ppm Mg/ppm Value 99.13 2.54 2.72 41.99 19.74 24.97 Al/ppm Zn/ppm Ti/ppm Zr/ppm Na/ppm K/ppm 24.43 4.1 548 35.1 126.6 9.47

TABLE-US-00003 TABLE 3 Contents of the Fe.sub.3O.sub.4 obtained in Example 1 major component Item content Ni/ppm Co/ppm Mn/ppm Ca/ppm Mg/ppm Value 99.01 0.72 3.08 7.89 8.55 16.27 Al/ppm Zn/ppm Zr/ppm Na/ppm K/ppm 40.61 11.08 93.84 54.72 32.31

[0068] As shown in the table 1-3, the method of present disclosure has a lithium recovery rate more than 95%, and produces lithium phosphate and Fe.sub.3O.sub.4 with high purity. The lithium phosphate product can be applied in preparation of lithium iron phosphate cathode material and other materials with industrial utilization. And Fe.sub.3O.sub.4 can be applied in manufacture of pigments, polishing agents, and audio tapes and telecommunications equipment.

[0069] The method for recycling a lithium iron phosphate waste and application thereof provided by the present disclosure are described in detail above. Specific examples are used in this article to illustrate the principle and implementation of the present disclosure. The description of the above examples is only used to help understand the method and core idea of the present disclosure, including the best mode, and also enables any person skilled in the art to practice the present disclosure, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present disclosure, several improvements and modifications can be made to the present disclosure, and these improvements and modifications also fall within the protection scope of the claims of the present disclosure. The scope of patent protection of the present disclosure is defined by the claims, and may include other embodiments that those skilled in the art can think of. If these other embodiments have structural elements that are not different from the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, these other embodiments should also be included in the scope of the claims.