A method for selectively extracting lithium by introducing a water vapor atmosphere to assist the co-pyrolysis of the cathode of spent lithium manganese oxide batteries and brominated epoxy resin

Abstract

The present invention discloses a method for selectively extracting lithium by introducing a water vapor atmosphere to assist the co-pyrolysis of waste lithium manganese oxide batteries and brominated epoxy resin, belonging to the field of recycling of lithium battery waste. The method comprises the following steps: fully mixing the waste lithium manganese oxide cathode material with brominated epoxy resin powder to obtain a mixed powder; introducing water vapor into the mixed powder and heating to 180-450 °C under an inert gas atmosphere to carry out a co-pyrolysis reaction; impregnating the pyrolysis residue with a dilute acid solution to separate manganese oxide and a lithium solution. The present invention has the advantages of a short process flow, a high lithium extraction rate, and a high lithium selectivity.

Description

Technical Field

[0001] The present invention belongs to the field of recycling of lithium battery waste, and relates to a method for selectively extracting lithium by introducing a water vapor atmosphere to assist the co-pyrolysis of the positive electrode of waste lithium manganese oxide batteries and brominated epoxy resin. Background Art

[0002] With the rapid development of electric vehicles and renewable energy, the use of lithium-ion batteries has become increasingly popular, and the resource recovery of waste lithium batteries has become particularly important. Recycling waste lithium batteries efficiently and environmentally can, on the one hand, recover high-value resources such as lithium, copper, aluminum, and iron, effectively solving the problem of lithium resource shortage; on the other hand, it can solve the potential pollution problems of electrolytes and heavy metals in waste lithium batteries.

[0003] Currently, the main methods for recycling the positive electrode materials of waste lithium-ion batteries are pyrometallurgical processes and hydrometallurgical processes. The pyrometallurgical process is a method for removing binders and the like in waste lithium batteries by high temperature to realize the enrichment and recovery of positive and negative electrode powders. It has the advantages of short process flow and simple process. However, the pyrometallurgical process has high energy consumption, serious environmental pollution, and cannot achieve efficient lithium recovery; the hydrometallurgical process refers to dissolving the positive electrode materials rich in metals with acid, and then realizing the separation and purification of multiple metals through a series of methods such as complexation, chelation, extraction, and precipitation. However, it has problems such as long process flow, large consumption of chemical reagents, large amount of wastewater, serious lithium loss, and low lithium recovery rate. Therefore, it is necessary to find a method for efficiently and environmentally extracting lithium.

[0004] The prior art has studied the resource recovery of waste lithium batteries. For example, CN117127027A discloses a method for extracting valuable metal elements from waste ternary batteries using salt essence. The method is to mix the powder obtained by discharging, crushing, and screening waste ternary lithium-ion batteries with ammonium chloride, and bake it in a covered mullite crucible. The baked product is leached with water and filtered to obtain a filtrate; saturated sodium hydroxide is added to the filtrate and centrifuged to obtain nickel cobalt manganese hydroxide and a clear liquid; saturated sodium carbonate is added to the clear liquid to obtain crude lithium carbonate crystals.

[0005] However, the prior art has the disadvantages of long process flow, high energy consumption, and high lithium loss rate. It is necessary to develop a method for efficiently, low-energy-consuming, and highly selectively extracting lithium resources from waste lithium batteries. Summary of the Invention

[0006] The object of the present invention is to overcome the disadvantages of high energy consumption and low selectivity existing in the prior art, and to provide a method for selectively extracting lithium by co-pyrolysis of the positive electrode of waste lithium manganese oxide batteries and brominated epoxy resin assisted by water vapor. Superheated water vapor is used to promote the decomposition reaction of brominated epoxy resin, generating hydrogen bromide and a large amount of reducing gases rich in propane, benzene, bromophenol, etc. Among them, hydrogen bromide can react with waste lithium manganate to produce water-soluble lithium bromide, and at the same time, reducing gases such as propane, benzene, and bromophenol react with waste lithium manganate to produce manganese oxide and water-soluble lithium oxide. The separation of lithium and manganese oxide can be achieved through weak acid leaching, thereby realizing the selective recovery of lithium.

[0007] To achieve the above object, the present invention provides a method for selectively extracting lithium by co-pyrolysis of the positive electrode of waste lithium manganese oxide batteries and brominated epoxy resin assisted by water vapor, which includes the following specific steps: (1) fully mixing the waste lithium manganate positive electrode material with brominated epoxy resin powder to obtain a mixed powder; (2) under an inert gas atmosphere, introducing water vapor into the mixed powder and heating it to 180-450 °C to cause a co-pyrolysis reaction; (3) impregnating the pyrolysis residue with a dilute solution of an acid, and separating to obtain manganese oxide and a lithium solution.

[0008] Further, in the step (1), the mass ratio of waste lithium manganate to brominated epoxy resin is 1:(0.2-3).

[0009] Further, in the step (1), the grinding method is stirring, or ball milling, or a combination of stirring and ball milling. The particle size of waste lithium manganate is less than 3 mm, and the particle size of brominated epoxy resin is less than 1 mm.

[0010] Further, in the step (2), the inert gas is nitrogen with a purity greater than 99%, or argon with a purity greater than 99%, or helium with a purity greater than 99%, or a mixed gas composed of nitrogen, argon, and helium in any ratio.

[0011] Further, in the step (2), the co-pyrolysis temperature is 180-450 °C, the heating rate is 1-20 °C / min, the treatment time is 0.5-5 h, the argon flow rate is 1-10 L / min, and the mass ratio of water vapor to the mixed powder is 1:(10-100).

[0012] Further, in the step (3), the acid is dilute sulfuric acid, or dilute nitric acid, or dilute hydrochloric acid, or a mixed acid composed of dilute sulfuric acid, dilute nitric acid, and dilute hydrochloric acid in any proportion, and its acid concentration is 10 -3 mol / L~10 -6 mol / L.

[0013] Further, in the step (3), the impregnation conditions are: the solid-liquid ratio of the pyrolysis residue to the dilute solution of the acid is 1:(3-10), the impregnation temperature is 20-60 °C, the impregnation time is 0.5-3 h, and the stirring rate is 50-200 rmp.

[0014] Further, the separation method in step (3) is filtration or centrifugation.

[0015] The present invention designs a method for selectively extracting lithium by co-pyrolysis of water vapor-assisted catalytic brominated epoxy resin and waste lithium manganese oxide batteries. After uniformly mixing lithium manganese oxide and brominated epoxy resin, co-pyrolysis is carried out in a water vapor atmosphere. On the one hand, the addition of water vapor can weaken the bond energies of C-O bonds and C-Br bonds in brominated epoxy resin, causing brominated epoxy resin to decompose at a lower temperature to produce reducing gases such as hydrogen bromide, propane, and bromophenol. On the other hand, water vapor can react with the coke produced by the pyrolysis of brominated epoxy resin to generate reducing gases such as carbon monoxide. The generated hydrogen bromide can react with waste lithium manganese oxide to produce lithium bromide, and at the same time, the generated reducing gases can react with waste lithium manganese oxide to produce manganese oxide and lithium oxide. Then, through dilute acid impregnation, a lithium solution and solid manganese oxide can be obtained, realizing the selective extraction of lithium.

[0016] Compared with the prior art, the present invention introduces a water vapor atmosphere to promote the decomposition of brominated epoxy resin to produce hydrogen bromide and reducing gases, thereby promoting the bromination reaction and reduction reaction with waste lithium manganese oxide to achieve the selective extraction of lithium. The present invention has the advantages of low energy consumption, high lithium selectivity, and simple process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the XRD pattern of the calcination product of Example 1 related to the present invention. The red marked line is the standard card JCPD#75-0626-MnO of manganese oxide.

[0018] Figure 2 It is a schematic diagram of the lithium extraction rate in Examples 1 and 2 and Comparative Examples 3 and 4 related to the present invention. The red curve is the lithium extraction rate when water vapor is introduced, and the black curve is the lithium extraction rate when water vapor is not introduced. DETAILED DESCRIPTION OF THE INVENTION

[0019] The technical solutions of the present invention will be described in detail below through specific examples in combination with the drawings. For those not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are all conventional products that can be obtained through commercial purchase.

[0020] Example 1: Weigh waste lithium manganese oxide and brominated epoxy resin powder according to a mass ratio of 1:1.2. Through stirring, the two are fully mixed and the particle size of waste lithium manganese oxide is less than 3 mm, and the particle size of brominated epoxy resin is less than 1 mm. Then, the mixed powder is placed in a co-pyrolysis device. Under the condition that the argon flow rate is 3 L / min, it is heated to 300 °C at a rate of 10 °C / min, and the co-pyrolysis reaction time is 70 min. The mass ratio of water vapor to the mixed powder is 1:20. After the reaction is completed, the pyrolysis residue and a concentration of 10-4 Impregnate with a dilute sulfuric acid solution of Figure 2 1 mol / L at a solid-liquid ratio of 1:5, with an impregnation temperature of 50 °C, an impregnation time of 2 h, and a stirring rate of 100 rmp. Then filter to obtain the lithium filtrate, and the results are as

[0021] Example 2: Weigh spent lithium manganate and brominated epoxy resin powder according to a mass ratio of 1:1.2, and fully mix the two by stirring to make the particle size of spent lithium manganate less than 3 mm and the particle size of brominated epoxy resin less than 1 mm. Then place the mixed powder in a co-pyrolysis device. Under the condition of an argon flow rate of 3 L / min, heat it up to 350 °C at a rate of 10 °C / min, and the co-pyrolysis reaction time is 70 min. The mass ratio of water vapor to the mixed powder is 1:20. After the reaction is completed, impregnate the pyrolysis residue with a dilute sulfuric acid solution of 10-4 mol / L at a solid-liquid ratio of 1:5, with an impregnation temperature of 50 °C, an impregnation time of 2 h, and a stirring rate of 100 rmp. Then filter to obtain the lithium filtrate, and the results are as Figure 2 shown, and the lithium extraction rate is 95.49%.

[0022] Comparative Example 1: This comparative example is similar to Example 1, except that water vapor is not introduced in this comparative example. The specific steps are as follows: Weigh spent lithium manganate and brominated epoxy resin powder according to a mass ratio of 1:1.2, and fully mix the two by stirring to make the particle size of spent lithium manganate less than 3 mm and the particle size of brominated epoxy resin less than 1 mm. Then place the mixed powder in a co-pyrolysis device. Under the condition of an argon flow rate of 3 L / min, heat it up to 300 °C at a rate of 10 °C / min, and the co-pyrolysis reaction time is 70 min. After the reaction is completed, impregnate the pyrolysis residue with a dilute sulfuric acid solution of 10 -4 mol / L at a solid-liquid ratio of 1:5, with an impregnation temperature of 50 °C, an impregnation time of 2 h, and a stirring rate of 100 rmp. Then filter to obtain the lithium filtrate, and the results are as Figure 2 shown, and the lithium extraction rate is 75.19%.

[0023] Comparative Example 2: This comparative example is similar to Example 2, except that the co-pyrolysis temperature in this comparative example is 500 °C. The specific steps are as follows: Weigh spent lithium manganate and brominated epoxy resin powder according to a mass ratio of 1:1.2, and fully mix the two by stirring to make the particle size of spent lithium manganate less than 3 mm and the particle size of brominated epoxy resin less than 1 mm. Then place the mixed powder in a co-pyrolysis device. Under the condition of an argon flow rate of 3 L / min, heat it up to 500 °C at a rate of 10 °C / min, and the co-pyrolysis reaction time is 70 min. The mass ratio of water vapor to the mixed powder is 1:20. After the reaction is completed, impregnate the pyrolysis residue with a dilute sulfuric acid solution of 10 -4The dilute sulfuric acid solution with a concentration of [[mol / L]] was impregnated at a solid-liquid ratio of 1:5, the impregnation temperature was 50 °C, the impregnation time was 2 h, and the stirring rate was 100 rmp. Then, the lithium filtrate was obtained by filtration, and the results are as Figure 2 shown, and the lithium extraction rate was 80.49%.

[0024] As described above, in a water vapor atmosphere, the utilization rate of brominated epoxy resin can be increased; and the bromination reaction with the positive electrode of waste lithium manganese oxide batteries can be accelerated, thereby selectively extracting lithium.

Claims

1. A method for selectively extracting lithium by introducing a water vapor atmosphere to assist the co-pyrolysis of the cathode of spent lithium manganese oxide batteries and brominated epoxy resin, characterized in that, The specific steps are as follows: (1) fully mixing waste lithium manganese oxide positive electrode material and brominated epoxy resin powder to obtain mixed powder; (2) introducing water vapor into the mixed powder obtained in step (1) under an inert gas atmosphere and heating it to 180-350°C to cause a co-pyrolysis reaction, with a heating rate of 1-20°C / min, to obtain pyrolysis slag; (3) impregnating the pyrolysis slag obtained in step (2) with a dilute acid solution to separate manganese oxide and lithium solution.

2. A method for selectively extracting lithium by co-pyrolyzing the cathode of waste lithium manganese oxide batteries and brominated epoxy resin with the assistance of a water vapor atmosphere as claimed in claim 1, characterized in that The mass ratio of waste lithium manganese oxide to brominated epoxy resin is 1: (0.2~3).

3. A method for selectively extracting lithium by co-pyrolyzing the cathode of spent lithium manganese oxide batteries and brominated epoxy resin with the assistance of a water vapor atmosphere according to claim 1, characterized in that, The grinding method is stirring, or ball milling, or a combination of stirring and ball milling. The particle size of the waste lithium manganese oxide is less than 3 mm, and the particle size of the brominated epoxy resin is less than 1 mm.

4. A method for selectively extracting lithium by co-pyrolyzing the positive electrode of spent lithium manganese oxide batteries and brominated epoxy resin with the assistance of a water vapor atmosphere according to claim 1, characterized in that, The inert gas is nitrogen with a purity greater than 99%, or argon with a purity greater than 99%, or helium with a purity greater than 99%, or a mixture of nitrogen, argon and helium in any ratio.

5. A method for selectively extracting lithium by co-pyrolysis of the cathode of spent lithium manganese oxide batteries and brominated epoxy resin with the assistance of a water vapor atmosphere as claimed in claim 1, characterized in that, The heating rate is 1~20℃ / min, the processing time is 0.5~5h, the argon flow rate is 1~10L / min, and the mass ratio of water vapor to mixed powder is 1:(10~100).

6. A method for selectively extracting lithium by introducing a water vapor atmosphere to assist in the co-pyrolysis of the cathode of a spent lithium manganese oxide battery and brominated epoxy resin according to claim 1, characterized in that, The acid is dilute sulfuric acid, or dilute nitric acid, or dilute hydrochloric acid, or a mixed acid composed of dilute sulfuric acid, dilute nitric acid and dilute hydrochloric acid in any proportion, and the acid concentration is 10 -3 mol / L to 10 -6 mol / L.

7. The method for selectively extracting lithium by co-pyrolysis of the cathode of waste lithium manganese oxide batteries and brominated epoxy resin assisted by introducing a water vapor atmosphere according to claim 1, characterized in that, The impregnation conditions are as follows: the solid-liquid ratio of the pyrolysis slag to the dilute acid solution is 1:(3~10), the impregnation temperature is 20~60°C, the impregnation time is 0.5~3h, and the stirring rate is 50~200rmp.

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