Method for recycling waste lithium iron phosphate based on ion balance method

Abstract

The application relates to a method for recycling waste lithium iron phosphate based on an ion balance method. The specific steps comprise the following: firstly, performing pretreatment such as discharging, disassembling and separating on a waste lithium iron phosphate battery to obtain lithium iron phosphate powder; ball-milling the lithium iron phosphate powder and silicon dioxide powder in proportion; adding the mixed powder composed of the lithium iron phosphate and the silicon dioxide into deionized water to configure a solution and placing the solution in an ultrasonic reactor; performing pre-aeration on the main reactor by using an aeration head before starting the reaction; keeping the aeration state, adding phosphoric acid solution into the reactor by using a conveying pump, and starting ultrasonic to perform the reaction; performing filtration and separation on the solid-liquid mixture after the reaction to obtain lithium ion solution and lithium iron phosphate precipitation. According to the treatment method, the valuable metal elements in the waste lithium iron phosphate can be recycled, the process flow is short, convenient and easy to operate, the consumption of chemical reagents is greatly reduced, the silicon dioxide powder can be recycled, and energy saving and environmental protection are achieved.

Description

Technical Field

[0001] This invention relates to the field of waste lithium-ion battery recycling, specifically to a method for recycling waste lithium iron phosphate based on the ion balance method. Background Technology

[0002] Promoting new energy vehicles globally is crucial for environmental protection, energy conservation, and emission reduction. With strong government support, the number of new energy vehicles is increasing year by year. It is projected that global sales of new energy vehicles will reach 18 million units by 2025, and exceed 30 million units by 2030. Lithium-ion batteries have seen rapid development in electric vehicles and energy storage systems due to their high capacity and long cycle life. However, lithium batteries typically have a lifespan of 3-5 years, and millions of tons of lithium-ion power batteries will face the problem of failure and retirement in the future. These spent lithium-ion batteries contain a large number of high-value elements, making them highly valuable for recycling and extraction. At the same time, the electrolyte and other organic components can easily cause environmental pollution, necessitating the secondary recycling of spent lithium-ion batteries. Therefore, choosing appropriate strategies for recycling spent lithium-ion batteries is of great significance for promoting energy conservation and emission reduction, environmental pollution control, and alleviating resource pressure in my country.

[0003] Currently, spent lithium-ion batteries are broadly categorized into lithium iron phosphate (LFP), lithium nickel cobalt manganese oxide (LCO), and lithium cobalt oxide (LCO) types based on their cathode materials. Among these, LFP batteries hold a significant market share (32% of the lithium battery industry) due to their high thermal stability and long lifespan. Recycling technologies for spent LFP batteries include pyrometallurgy, hydrochemical extraction, and direct recycling. Pyrometallurgy is suitable for large-scale production due to its durability against complex chemical compositions, but its low recovery rate and large gas emissions remain challenging. Direct recycling typically involves high-temperature calcination to replenish the lithium source, preserve the original structure, and repair damaged crystal lattices. However, this method has stringent requirements for raw materials, and the complex composition of actual spent lithium-ion batteries limits its large-scale engineering application. In contrast, hydrochemical extraction directly recovers the required elements from spent lithium-ion batteries, offering high efficiency and wide application. However, hydrochemical processes often use large amounts of chemicals, reducing the economic viability of recycling and generating severe secondary pollution.

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for recycling waste lithium iron phosphate based on the ion balance method. This process, based on wet leaching technology, adds silica as a reusable electron adsorbent to reduce oxygen and generate hydroxide anions. These hydroxide anions react with the waste lithium iron phosphate under the action of trace amounts of phosphoric acid to form ferric hydroxide precipitate and a lithium phosphate solution. Compared with traditional acid leaching, this significantly reduces the amount of acid used, providing a new technical feasibility for the wet recycling of waste lithium ions. Summary of the Invention

[0005] To address the aforementioned problems, the inventors conducted intensive research and provided a method for recycling waste lithium iron phosphate based on the ion balance method. Specifically, it includes:

[0006] S1, pre-processing the waste lithium iron phosphate batteries by discharging, dismantling and separating them to obtain lithium iron phosphate powder;

[0007] S2, Lithium iron phosphate powder and silicon dioxide powder are ball-milled in a certain proportion;

[0008] S3, a mixed powder of lithium iron phosphate and silicon dioxide is added to deionized water to prepare a solution and placed in an ultrasonic reactor;

[0009] S4, Pre-aeration is carried out in the ultrasonic reactor using an aeration head before the reaction begins;

[0010] S5, maintain aeration, add phosphoric acid solution to the reactor using a transport pump, and turn on ultrasound to carry out the reaction;

[0011] S6, the solid-liquid mixture after the reaction is filtered and separated to obtain lithium phosphate solution and iron hydroxide precipitate.

[0012] Based on the above technical solution, the present invention can be further improved as follows:

[0013] Furthermore, the waste lithium iron phosphate batteries in S1 are obtained from the scrapping of new energy vehicles.

[0014] Furthermore, in S2, the mass ratio of lithium iron phosphate powder to silica powder is 1:1 to 3:1, the ball milling frequency is 35 to 45 Hz, and the ball milling time is 2 to 4 hours.

[0015] Furthermore, the solid-liquid ratio of the mixed powder to deionized water in S3 is 1:20 to 1:40 (g / mL).

[0016] Furthermore, the gas used for pre-aeration in S4 is oxygen.

[0017] Furthermore, the gas flow rate for pre-aeration in S4 is 60–100 mL / min, and the aeration time is 2–4 h.

[0018] Furthermore, the concentration of the phosphoric acid solution pumped into S5 is 1 mol / L, and the reaction temperature is 40–70 °C.

[0019] The method for recycling waste lithium iron phosphate based on the ion balance method provided by the present invention has the following beneficial effects:

[0020] (1) The method of the present invention for treating waste lithium iron phosphate batteries is simple, efficient and convenient to operate, greatly reducing the recycling and processing costs and having good economic benefits.

[0021] (2) The method of the present invention realizes the closed-loop recycling of all elements of solid waste, and there is no harmful substance emission during the treatment process, which reduces environmental pollution and saves resources. Attached Figure Description

[0022] Figure 1 The diagram shows a process flow chart of a method for recycling waste lithium iron phosphate based on the ion balance method provided by the present invention. Detailed Implementation

[0023] The invention will now be described in detail with reference to the accompanying drawings, and its features and advantages will become clearer and more apparent from these descriptions.

[0024] See Figure 1 This invention provides a method for recycling waste lithium iron phosphate based on the ion balance method, comprising the following steps:

[0025] S1, pre-processing the waste lithium iron phosphate batteries by discharging, dismantling and separating them to obtain lithium iron phosphate powder;

[0026] S2, Lithium iron phosphate powder and silicon dioxide powder are ball-milled in a certain proportion;

[0027] S3, a mixed powder of lithium iron phosphate and silicon dioxide is added to deionized water to prepare a solution and placed in an ultrasonic reactor;

[0028] S4, Pre-aeration is carried out in the ultrasonic reactor using an aeration head before the reaction begins;

[0029] S5, maintain aeration, add phosphoric acid solution to the reactor using a transport pump, and turn on ultrasound to carry out the reaction;

[0030] S6, the solid-liquid mixture after the reaction is filtered and separated to obtain lithium phosphate solution and iron hydroxide precipitate.

[0031] Based on the above technical solution, the present invention can be further improved as follows:

[0032] Furthermore, the waste lithium iron phosphate batteries in S1 are obtained from the scrapping of new energy vehicles.

[0033] Furthermore, the mass ratio of lithium iron phosphate powder to silica powder in S2 is 1:1 to 3:1.

[0034] Furthermore, the solid-liquid ratio of the mixed powder to deionized water in S3 is 1:20 to 1:40 (g / mL).

[0035] Furthermore, the gas used for pre-aeration in S4 is oxygen.

[0036] Furthermore, the gas flow rate for pre-aeration in S4 is 60–100 mL / min, and the aeration time is 2–4 h.

[0037] Furthermore, the concentration of the phosphoric acid solution pumped into S5 is 1 mol / L, and the reaction temperature is 40–70 °C.

[0038] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for recycling waste lithium iron phosphate based on ion balance, characterized in that, Includes the following steps: S1, pre-processing the waste lithium iron phosphate batteries by discharging, dismantling and separating them to obtain lithium iron phosphate powder; S2, Lithium iron phosphate powder and silicon dioxide powder are ball-milled in a certain proportion; S3, a mixed powder of lithium iron phosphate and silicon dioxide is added to deionized water to prepare a solution and placed in an ultrasonic reactor; S4, Pre-aeration is carried out in the ultrasonic reactor using an aeration head before the reaction begins; S5, maintain aeration, add phosphoric acid solution to the reactor using a transport pump, and turn on ultrasound to carry out the reaction; S6, the solid-liquid mixture after the reaction is filtered and separated to obtain lithium phosphate solution and iron hydroxide precipitate.

2. The method for recycling waste lithium iron phosphate based on ion balance method according to claim 1, characterized in that: In S2, the mass ratio of lithium iron phosphate powder to silica powder is 1:1 to 3:1, the ball milling frequency is 35 to 45 Hz, and the ball milling time is 2 to 4 hours.

3. The method for recycling waste lithium iron phosphate based on ion balance method according to claim 1, characterized in that: The solid-liquid ratio of the mixed powder to deionized water in S3 is 1:20 to 1:40 (g / mL).

4. The method for recycling waste lithium iron phosphate based on ion balance method according to claim 1, characterized in that: The gas used for pre-aeration in S4 is oxygen.

5. The method for recycling waste lithium iron phosphate based on ion balance method according to claim 1, characterized in that: The gas flow rate for pre-aeration in S4 is 60–100 mL / min, and the aeration time is 2–4 h.

6. The method for recycling waste lithium iron phosphate based on ion balance method according to claim 1, characterized in that: The concentration of phosphoric acid solution pumped into S5 is 1 mol / L, and the reaction temperature is 40–70℃.

Images