A method for separating and recovering valuable metals from the cathode waste of lithium-ion batteries

Abstract

The present invention discloses a method for separating and recovering valuable metals from the positive electrode waste of lithium-ion batteries, which comprises the following steps: fully mixing the positive electrode waste of the battery with CuCl2, placing the mixture in a resistance furnace for vacuum chlorination roasting, keeping warm, controlling multiple-stage condensation temperature zones, and collecting the condensation products in the corresponding areas, namely the chlorides of lithium, nickel, cobalt, manganese, and aluminum. The present invention not only fully recovers the valuable metals Ni, Co, Mn, and Li in the positive electrode waste, but also removes the impurities Al and Cu in the waste, enabling the full recycling and utilization of the positive electrode waste of lithium-ion batteries; compared with the traditional leaching-precipitation method, it avoids the addition of leaching agents and precipitating agents, shortens the process flow, and has certain potential in future industrial applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of solid waste from lithium-ion batteries, and specifically relates to a method for separating and recovering valuable metals from the positive electrode waste of lithium-ion batteries. Background Art

[0002] With the shortage of metals such as Ni, Co, and Li, the prices of these valuable metals have been rising continuously. In order to meet the resources required for the production of lithium-ion batteries, the recycling of waste batteries has become increasingly important. At present, the mainstream method for extracting valuable metals from waste lithium-ion batteries is to transfer the valuable metals into a solution system using inorganic acids, organic acids, or mixed acids, and then use precipitants such as oxalic acid and carbonates to gradually separate the valuable metals Ni, Co, Mn, and Li by adjusting the pH value. In this process, nearly pure valuable metal compounds can be recovered. Acid leaching seems irreplaceable in the extraction of valuable metals from waste lithium-ion batteries, but the problems of waste acid and tail gas treatment have always troubled the further application of this method.

[0003] As a good solid waste treatment method, the chlorination process is widely used in the treatment and recovery of heavy metals in municipal solid waste (MSW), tailings, medical waste, nuclear waste, and other fields. In order to avoid acid loss and air pollution caused by the volatilization of hydrochloric acid, researchers have gradually used non-volatile chlorinating agents such as CaCl2, NaCl, and MgCl2 to replace HCl.

[0004] According to relevant literature reports, in the research on the acid leaching process in the field of lithium-ion battery recycling, nearly half of the methods still use hydrochloric acid as a reducing agent or leaching agent. In order to improve this situation, a chlorination roasting method has been proposed, in which the valuable metal Li in the waste battery is chlorinated with the chlorinating agent CaCl2, and then immersed in water to obtain an LiCl aqueous solution for subsequent treatment. By strictly controlling the process conditions, this process can separate the valuable metal lithium in the lithium-ion battery waste, and has good selectivity. However, the chlorinating agent used is soluble in water, which will introduce additional impurity elements; the by-products obtained will react with water, complicating the solution system and bringing certain impacts and challenges to the ecological environment. The research on the chlorination process is mainly carried out under atmospheric pressure conditions, and there is currently no research on the transformation and volatilization of heavy metals under vacuum and high-temperature treatment conditions by Cl. Therefore, it is particularly important to study the thermodynamics of the transformation and volatilization of chlorides under vacuum-high temperature coupling conditions.

[0005] Therefore, in order to solve the above problems, this paper proposes a method for separating and recovering valuable metals from the positive electrode waste of lithium-ion batteries. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention designs a method for separating and recovering valuable metals from positive electrode waste of lithium-ion batteries, which not only fully recovers the valuable metals Ni, Co, Mn and Li in the positive electrode waste, but also removes the impurities Al and Cu in the waste, so that the positive electrode waste of lithium-ion batteries can be fully recycled.

[0007] In order to achieve the above technical effects, the present invention is implemented by the following technical scheme: A method for separating and recovering valuable metals from lithium-ion battery positive electrode waste, characterized in that it comprises the following steps:

[0008] Step 1: Fully mix the lithium-ion battery cathode waste and CuCl2 in a molar ratio of 1:1.1-1.3 to obtain a mixture;

[0009] Step 2: The mixed material is placed in a resistance furnace for vacuum chlorination roasting. The vacuum chlorination roasting temperature is 730-850°C, the air pressure is 10-100 Pa, and the holding time is 0.5-2h;

[0010] Step 3: Control the condensation temperature zones to 726-835°C, 602-725°C, 575-601°C, 352-574°C, and 100-351°C, and collect condensation products in the corresponding areas. The condensation products are chlorides of lithium, nickel, cobalt, manganese, and aluminum.

[0011] Further, the following steps are included:

[0012] Step 1: Fully mix the lithium-ion battery cathode waste and CuCl2 in a molar ratio of 1:1.2 to obtain a mixture;

[0013] Step 2: The mixed material is placed in a resistance furnace for vacuum chlorination roasting. The vacuum chlorination roasting temperature is 850°C, the air pressure is 100Pa, and the holding time is 0.5h;

[0014] Step 3: Control the condensation temperature zones to 726°C, 602°C, 575°C, 352°C, and 100°C, and collect the condensation products in the corresponding areas. The condensation products are chlorides of lithium, manganese, nickel, cobalt, and aluminum.

[0015] Furthermore, the lithium-ion battery positive electrode waste includes ternary nickel cobalt manganese oxide (NCM), ternary nickel cobalt aluminum oxide (NCA), lithium nickel oxide (LNO), lithium cobalt oxide (LCO) and lithium manganese oxide (LMO).

[0016] The beneficial effects of the present invention are:

[0017] CuCl2 as a chlorinating agent can significantly destroy the spinel structure of lithium-ion battery positive electrode waste, and can make the temperature required for the chlorination reaction close to the theoretical value; CuCl2 reacts with impurities Al and Cu in the positive electrode waste to generate volatile AlCl3 and non-volatile CuCl and CuO, which can remove these two impurities that are difficult to separate through automated production; not only can the valuable metals Ni, Co, Mn and Li in the positive electrode waste be fully recovered, but also the impurities Al and Cu in the waste are removed, so that the positive electrode waste of lithium-ion batteries can be fully recycled; compared with the traditional leaching-precipitation method, it avoids the addition of leaching agents and precipitants, shortens the process flow, and has certain potential for industrial application in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0019] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] A method for separating and recovering valuable metals from lithium-ion battery cathode waste (see Figure 1 ), the specific steps are as follows:

[0023] (1) 10.2 g NCM-523 (the mass contents of Li, Ni, Co, Mn, Al and Cu are 6.82%, 28.85%, 11.59%, 16.20%, 2.65% and 1.25%, respectively) was fully mixed with 24.7 g CuCl2 and calcined at 10 Pa and 730 °C for 2 h;

[0024] (2) The temperatures of the condensation zones were controlled at 726 °C, 575 °C, 352 °C, 602 °C and 100 °C respectively. The masses of LiCl, NiCl2, CoCl2, MnCl2 and AlCl3 collected in the corresponding zones were 4.2 g, 6.4 g, 2.6 g, 3.7 g and 1.3 g respectively, and the purities were 96.2%, 98.3%, 99.1%, 99.2% and 99.5% respectively. The comprehensive recovery rate was 99%; the mass of the roasting residue in the crucible was 18.5 g.

[0025] Reducing the air pressure in the system can significantly reduce the temperature of chlorination roasting and correspondingly reduce the temperature of the condensation zone. However, the overall low temperature in the reaction system makes the chlorination roasting controlled by the chemical reaction rate, and the roasting time needs to be extended accordingly. At the same time, appropriately reducing the temperature of the condensation zone is more conducive to the condensation of chlorination products and improves the recovery rate of valuable metals. A too low condensation temperature easily causes components with lower boiling points (sublimation points) to condense in advance, resulting in a decrease in purity.

[0026] Example 2

[0027] A method for separating and recovering valuable metals from the positive electrode waste of lithium-ion batteries (see Figure 1 ), the specific steps are as follows:

[0028] (1) 10.1 g of NCM-622 (the mass contents of Li, Ni, Co, Mn, Al and Cu accounted for 6.89%, 34.95%, 11.70%, 10.91%, 1.34% and 1.26% respectively) was fully mixed with 27.9 g of CuCl2 and roasted at 100 Pa and 850 °C for 0.5 h;

[0029] (2) The temperatures of the condensation zones were controlled at 835 °C, 601 °C, 574 °C, 725 °C and 351 °C respectively. The masses of LiCl, NiCl2, CoCl2, MnCl2 and AlCl3 collected in the corresponding zones were 4.1 g, 7.5 g, 2.5 g, 2.4 g and 6.4 g respectively, and the purities were 99.3%, 98.8%, 98.6%, 98.0% and 98.5% respectively. The comprehensive recovery rate was 96%; the mass of the roasting residue in the crucible was 22.2 g.

[0030] Increasing the air pressure in the system requires an appropriate increase in the temperature of chlorination roasting and a corresponding increase in the temperature of the condensation zone. A higher roasting temperature helps the chlorination reaction proceed and also helps the volatilization of chlorination products, which can shorten the time required for the chlorination reaction. However, increasing the temperature of the condensation zone will cause incomplete condensation of chlorination products with higher boiling points, thus doping into other chlorination products, resulting in a low recovery rate of valuable metals and a decrease in the purity of low-boiling components.

[0031] Example 3

[0032] A method for separating and recovering valuable metals from lithium-ion battery cathode waste (see Figure 1 ), the specific steps are as follows:

[0033] (1) 10.2 g NCM-811 (the mass contents of Li, Ni, Co, Mn, Al and Cu are 6.82%, 46.13%, 5.79%, 5.40%, 1.99% and 1.25%, respectively) was fully mixed with 26.3 g CuCl2 and calcined at 50 Pa and 780 °C for 1 h;

[0034] (2) The temperatures in the condensation zones were controlled to be 762°C, 584°C, 426°C, 643°C and 267°C, respectively. The masses of LiCl, NiCl2, CoCl2, MnCl2 and AlCl3 collected in the corresponding zones were 4.1 g, 10.1 g, 1.3 g, 1.2 g and 1.0 g, respectively, with purities of 99.3%, 99.0%, 99.2%, 98.8% and 99.5%, respectively, and the comprehensive recovery rate was 98%. The mass of the calcined slag in the crucible was 20.5 g.

[0035] Chlorination roasting under moderate temperature and pressure conditions is conducive to reducing reaction energy consumption, reducing the amount of chlorinating agent CuCl2 added, and reducing the amount of roasting slag produced. It can be found from the three embodiments that the change of condensation temperature has a significant effect on NiCl2 and CoCl2: when the condensation temperature is reduced, the purity of NiCl2 and CoCl2 is improved; the opposite is true when the condensation temperature is increased. Therefore, after comprehensively considering factors such as chlorination reaction efficiency, valuable metal recovery rate and condensation efficiency, a higher reaction temperature and a lower condensation temperature should be preferred.

[0036] The traditional leaching-precipitation method for recovering valuable metals from lithium-ion battery positive electrode waste usually requires the use of an acidic leaching agent to transfer the metal into a solution in the form of soluble ions, and then a precipitant is used to adjust the pH and precipitate separately. The leaching rate and precipitation rate of the traditional method are both about 99%, and the product purity is about 99.5%. From this, it can be calculated that the comprehensive recovery rate of valuable metals is about 97.5%. The recovery rate of valuable metals in the present invention is basically the same as that of the traditional method, but the addition of leaching agents and precipitants is avoided, the process flow is shortened, and it has certain potential for industrial application in the future.

Claims

1. A method for separating and recovering valuable metals from the positive electrode waste of a lithium-ion battery, characterized in that, The following steps are involved: Step 1: Fully mix the lithium-ion battery cathode waste and CuCl2 in a molar ratio of 1:1.1-1.3 to obtain a mixture; Step 2: The mixed material is placed in a resistance furnace for vacuum chlorination roasting. The vacuum chlorination roasting temperature is 730-850°C, the air pressure is 10-100 Pa, and the insulation time is 0.5-2h; Step 3: Control the condensation temperature zones to 726-835°C, 602-725°C, 575-601°C, 352-574°C, and 100-351°C, and collect condensation products in the corresponding areas. The condensation products are chlorides of lithium, nickel, cobalt, manganese, and aluminum.

2. The method for separating and recovering valuable metals from the positive electrode waste of a lithium-ion battery according to claim 1, wherein, The following steps are involved: Step 1: Fully mix the lithium-ion battery cathode waste and CuCl2 in a molar ratio of 1:1.2 to obtain a mixture; Step 2: The mixed material is placed in a resistance furnace for vacuum chlorination roasting. The vacuum chlorination roasting temperature is 850°C, the air pressure is 100Pa, and the holding time is 0.5h; Step 3: Control the condensation temperature zones to 726°C, 602°C, 575°C, 352°C, and 100°C, and collect the condensation products in the corresponding areas. The condensation products are chlorides of lithium, manganese, nickel, cobalt, and aluminum.

3. A method for separating and recovering valuable metals from the positive electrode waste of a lithium-ion battery according to claim 1, characterized in that: The lithium-ion battery positive electrode waste includes ternary nickel cobalt manganese oxide (NCM), ternary nickel cobalt aluminum oxide (NCA), lithium nickel oxide (LNO), lithium cobalt oxide (LCO) and lithium manganese oxide (LMO).

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