Process for selective extraction of valuable metals from lithium batteries

Abstract

The present invention relates to a process for the selective extraction of valuable metals from lithium batteries, including steps such as discharging, separating the cathode material, heat treatment, acid leaching, coprecipitation, lithium precipitation, etc., to achieve the efficient recovery and utilization of valuable metals in waste lithium batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste lithium battery recycling, and specifically relates to a process for the selective extraction of valuable metals from lithium batteries. Background Art

[0002] The cathode material LiFePO4 of lithium batteries has been widely used in fields such as mobile phones and electric vehicles because of its advantages such as high discharge specific capacity, relatively stable discharge platform, good cycle stability, thermal stability, and low price. In recent years, the output of lithium iron phosphate batteries has gradually increased, resulting in a gradual increase in the scrapping amount of lithium iron phosphate batteries. The batteries contain toxic chemical substances and high-value metals and must be recycled to promote environmental protection and sustainable development. The pretreatment process of waste lithium batteries mainly includes processes such as classification, discharging, disassembling, crushing, and separating and removing organic binders, and finally obtains black powder rich in cathode materials. Therefore, through the research on acid leaching and other treatments of waste lithium batteries, the present invention improves the recovery of various valuable metals.

[0003] In traditional wet leaching, the acid leaching process of cathode materials often uses an acid + reducing agent leaching system. Currently, H2O2 is widely used as a reducing agent, which has the advantages of being green, environmentally friendly, and pollution-free, but has problems such as a relatively low thermal decomposition temperature, inconvenient transportation, and storage. Recently, some scientific researchers have begun to try to use natural products as reducing agents, and substances with reducing groups such as macadamia nut shells, orange peels, and starches are also often used as reducing agents in the acid leaching process. These reducing agents are more green and environmentally friendly, and are also safe and convenient for transportation or storage. Some research has used the natural product tea polyphenols as a reducing agent to construct a sulfuric acid - tea polyphenol leaching system, achieving high-selectivity recovery of various metal ions. Therefore, selecting a natural and efficient reducing agent is the research focus of the present invention.

[0004] By stepwise precipitation treatment of various valuable metals in waste lithium batteries under different process conditions for recovery and extraction, the recovery efficiency can be effectively improved, environmental pollution can be reduced, and the recycling of resources can be promoted. Therefore, how to efficiently recover valuable metals by stepwise precipitation is the research focus of the present invention. Summary of the Invention

[0005] The purpose of the present invention is to provide a process for the selective extraction of valuable metals from lithium batteries.

[0006] To solve the above technical problems, the specific process of the present invention is as follows:

[0007] A process for the selective extraction of valuable metals from lithium batteries, including discharging, separating the cathode material, heat treatment, acid leaching, co-precipitation, and lithium precipitation, is characterized in that: the acid leaching treatment is as follows: adding sulfuric acid with a mass fraction of 10% to the ground cathode raw material, the ratio of sulfuric acid to the reducing agent is 8:2-3, the solid-liquid ratio is 30 g / L, the reaction temperature is 55-60 °C, the time is 60 min, the stirring speed is controlled at 400-600 rpm, and after leaching, filtration is carried out to obtain a filtrate;

[0008] Among them, the reducing agent is a gallocatechin solution with a mass fraction of 40-50%.

[0009] Among them, the co-precipitation treatment is to add a co-precipitant with a mass fraction of 30-50%, a reaction temperature of 40-50 °C, a stirring speed of 400-500 rpm, and a reaction time of 60 min to the leaching solution. At this time, a ternary cathode material precursor and a lithium-rich solution can be obtained.

[0010] Among them, the co-precipitant is a hydroxylamine sulfonic acid solution with a mass fraction of 20-30%.

[0011] A process for the selective extraction of valuable metals from lithium batteries is carried out according to the following steps:

[0012] Battery discharging: Discharging the used battery with a 5% NaCl solution for 24 h, and mechanically separating the battery core to obtain the positive electrode, negative electrode, and separator;

[0013] Separation of the cathode material: Cutting the cathode plate into small pieces of 1x1 cm and soaking them in a 15% NMP solution, ultrasonic stirring at 240 w at 100 °C for 1 h to accelerate the separation of the cathode material and dissolve the PVDF binder;

[0014] Heat treatment: After the separated cathode material is calcined in a muffle furnace at 700 °C for 2 h, it is ground and used as the raw material for acidolysis;

[0015] Lithium precipitation: Further precipitating the lithium-rich solution after acid leaching and co-precipitation treatment, adding a NaOH solution to the lithium-rich solution to adjust the solution pH to 9-11, adding a lithium precipitant with a mass fraction of 30-40%, and reacting at 90-95 °C with a stirring speed of 200-400 rpm for 2 h to obtain a precipitate.

[0016] Among them, the lithium precipitant is a 5'-inosinic acid disodium solution with a mass fraction of 32-46%.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. Through steps such as discharging, separating the cathode material, heat treatment, acid leaching, co-precipitation, and lithium precipitation, the present invention realizes the efficient recovery and utilization of valuable metals in waste lithium batteries. By using a natural reducing agent in combination with acid leaching, it environmentally friendly improves the extraction and leaching of valuable metals, and maximizes the precipitation recovery of valuable metals by means of stepwise precipitation, reducing the loss of valuable metals.

[0019] 2. Among them, the phenolic hydroxyl group of gallocatechin can reduce metal ions or metal oxides by providing electrons. During the acid leaching process, metal ions often exist in a high-valent state, and the phenolic hydroxyl group of gallocatechin can react with these metal ions to reduce them to low-valent metals, promoting their dissolution and leaching. During the acid leaching process, sulfuric acid provides an acidic environment conducive to dissolving metal compounds, while gallocatechin promotes the dissolution of metals through reduction, improving the leaching efficiency. This reaction process releases heat more significantly, increasing the collision frequency between molecules, thereby accelerating the progress of the reaction.

[0020] 3. Compared with tea polyphenols, gallocatechin as a reducing agent in waste battery recycling has higher reducing ability, better stability and selectivity, lower environmental hazards, and also has certain advantages in terms of cost and raw material supply. It can significantly improve the efficiency and environmental friendliness of waste lithium battery recycling, reduce the discharge of harmful wastewater, and lower the cost of wet leaching.

[0021] 4. The present invention uses the co-precipitation method to adjust the pH to precipitate nickel, cobalt, and manganese ions in the leaching solution and obtain a precursor product with good morphology and phase structure. Due to the reduction of hydroxylamine sulfonic acid, it can more effectively reduce target metal ions, thereby improving the purity of the precipitate. By adjusting the concentration of hydroxylamine and reaction conditions, the generation of by-products can be reduced and the selectivity of precipitation can be enhanced.

[0022] 5. The addition of hydroxylamine sulfonic acid can be carried out within a relatively wide pH range, while other types of reducing agents are more sensitive to pH changes. Oxalate shows the best precipitation effect at a lower pH and is less reactive in a neutral or alkaline environment. In contrast, the reducing property of hydroxylamine sulfonic acid can effectively play a role under a wider range of acid-base conditions, with stronger adaptability. The reduction rate of hydroxylamine in hydroxylamine sulfonic acid is relatively mild, which can control the particle size distribution during precipitation. A relatively uniform reduction reaction can ensure that the particle size of the precipitate is small and evenly distributed.

[0023] 6. In a lithium-rich solution, there is usually a certain salt effect. The salt effect enhances the solvation effect and weakens the interaction between ions, resulting in the ineffective contact and reaction of ions in the solution during the reaction process. The phosphate group in disodium xanthosine monophosphate has a strong affinity for lithium ions, which can effectively increase the collision probability between phosphate ions and lithium ions in the solution, thereby promoting the formation of lithium phosphate. The phosphate group of 5'-disodium xanthosine monophosphate can effectively form a complex with lithium ions, reduce the influence of ionic strength in the solution, overcome the inhibitory effect of the salt effect, and promote the precipitation of lithium phosphate. Disodium xanthosine monophosphate not only improves the reaction efficiency between lithium ions and phosphate ions through the phosphate group in its structure, but also the purine ring part can play a certain role in stabilizing the structure in the solution, making the phosphate ions more stable in the solution and not easily interfered by other salt ions, thereby improving the efficiency of lithium precipitation. Detailed implementation mode

[0024] The present invention will be further described in detail below with reference to the embodiments. The waste lithium battery is a nickel cobalt manganese lithium oxide battery (NCM523 type). The waste battery is discharged for 24 h with a 5% NaCl solution by mass fraction, and the battery core is mechanically separated to obtain the positive electrode, negative electrode and separator; the positive electrode plate is cut into small pieces of 1x1 cm and soaked in a 15% NMP solution, and stirred at 240 w for 1 h at 100 °C to accelerate the separation of the positive electrode material and dissolve the PVDF binder; the separated positive electrode material is calcined in a muffle furnace at 700 °C for 2 h and then ground to be used as the raw material for acidolysis; the following tests are carried out.

[0025] Example 1

[0026] Acid leaching treatment: Add sulfuric acid with a mass fraction of 10% to the ground positive electrode raw material, and the reducing agent is a gallocatechin solution with a mass fraction of 45%. The ratio of sulfuric acid to the reducing agent is 8:2.5, the solid-liquid ratio is 30 g / L, the reaction temperature is 58 °C, the time is 60 min, the stirring speed is controlled at 500 rpm, and after leaching, filter to obtain the filtrate;

[0027] Example 2

[0028] Acid leaching treatment: Add sulfuric acid with a mass fraction of 10% to the ground positive electrode raw material, and the reducing agent is a gallocatechin solution with a mass fraction of 40%. The ratio of sulfuric acid to the reducing agent is 8:2, the solid-liquid ratio is 30 g / L, the reaction temperature is 60 °C, the time is 60 min, the stirring speed is controlled at 400 rpm, and after leaching, filter to obtain the filtrate;

[0029] Example 3

[0030] Acid leaching treatment: Add sulfuric acid with a mass fraction of 10% to the ground cathode raw material. The reducing agent is a gallocatechin solution with a mass fraction of 50%. The ratio of sulfuric acid to the reducing agent is 8:3, the solid-liquid ratio is 30 g / L, the reaction temperature is 55 °C, the time is 60 min, the stirring speed is controlled at 600 rpm. After leaching, filter to obtain a filtrate;

[0031] Comparative Example 1

[0032] The difference between this comparative example and Example 1 is that the gallocatechin solution in this comparative example is a tea polyphenol solution, and the rest is the same as in Example 1.

[0033] Comparative Example 2

[0034] The difference between this comparative example and Example 1 lies in the different addition amounts of the gallocatechin solution. Specifically, for the acid leaching treatment: Add sulfuric acid with a mass fraction of 10% to the ground cathode raw material. The reducing agent is a gallocatechin solution with a mass fraction of 45%. The ratio of sulfuric acid to the reducing agent is 8:4, the solid-liquid ratio is 30 g / L, the reaction temperature is 58 °C, the time is 60 min, the stirring speed is controlled at 500 rpm. After leaching, filter to obtain a filtrate; the rest is the same as in Example 1.

[0035] Comparative Example 3

[0036] The difference between this comparative example and Example 1 lies in the different addition amounts of the gallocatechin solution. Specifically, for the acid leaching treatment: Add sulfuric acid with a mass fraction of 10% to the ground cathode raw material. The reducing agent is a gallocatechin solution with a mass fraction of 45%. The ratio of sulfuric acid to the reducing agent is 8:1, the solid-liquid ratio is 30 g / L, the reaction temperature is 58 °C, the time is 60 min, the stirring speed is controlled at 500 rpm. After leaching, filter to obtain a filtrate; the rest is the same as in Example 1.

[0037] Experiment 1: Leaching rate

[0038] Take the filtrate after acid leaching treatment, detect the metal ion concentration, and measure the leaching rate (ξ).

[0039]

[0040] c is the numerical value of the concentration of ions in the leaching solution, with the unit g / L; V is the numerical value of the volume of the leaching solution, with the unit L; m is the numerical value of the mass of the raw material, with the unit g; w is the numerical value of the content of each valuable metal in the raw material, with the unit %.

[0041] The results are shown in Table 1.

[0042] Table 1

[0043] Sample Li Leaching Rate (%) Ni Leaching Rate (%) Co Leaching Rate (%) [[ID=V4]]Mn Leaching Rate (%) Example 1 99.84 99.46 99.58 99.21 Example 2 99.69 99.23 99.47 99.05 Example 3 99.78 99.31 99.52 99.14 Comparative Example 1 92.65 93.14 91.65 91.36 Comparative Example 2 97.48 98.02 96.48 97.08 Comparative Example 3 95.27 96.52 94.61 95.69

[0044] The following embodiments are all based on Example 1.

[0045] Example 4

[0046] Coprecipitation: Add a 25% mass fraction of 40% hydroxylamine sulfonic acid solution to the leaching solution, with a reaction temperature of 45°C, a stirring speed of 450 rpm, and a reaction time of 60 min. At this time, a ternary cathode material precursor and a lithium-rich solution can be obtained.

[0047] Lithium precipitation: Further precipitate the lithium-rich solution. Add a NaOH solution to adjust the pH of the solution to 10, add a 39% 5'-inosinic acid disodium solution with a mass fraction of 35%, and react at 92°C with a stirring speed of 300 rpm for 2 h to obtain a precipitate.

[0048] Example 5

[0049] Coprecipitation: Add a 20% mass fraction of 30% hydroxylamine sulfonic acid solution to the leaching solution, with a reaction temperature of 50°C, a stirring speed of 400 rpm, and a reaction time of 60 min. At this time, a ternary cathode material precursor and a lithium-rich solution can be obtained.

[0050] Lithium precipitation: Further precipitate the lithium-rich solution. Add a NaOH solution to adjust the pH of the solution to 11, add a 46% 5'-inosinic acid disodium solution with a mass fraction of 30%, and react at 90°C with a stirring speed of 400 rpm for 2 h to obtain a precipitate.

[0051] Example 6

[0052] Coprecipitation: Add a 30% mass fraction of 50% hydroxylamine sulfonic acid solution to the leaching solution, with a reaction temperature of 50°C, a stirring speed of 500 rpm, and a reaction time of 60 min. At this time, a ternary cathode material precursor and a lithium-rich solution can be obtained.

[0053] Lithium precipitation: Further precipitate the lithium-rich solution. Add a NaOH solution to adjust the pH of the solution to 11, add a 32% 5'-inosinic acid disodium solution with a mass fraction of 40%, and react at 95°C with a stirring speed of 200 rpm for 2 h to obtain a precipitate.

[0054] Comparative Example 4

[0055] The difference between this comparative example and Example 4 is that the hydroxylamine sulfonic acid in this comparative example is ammonium oxalate; the rest is the same as Example 4.

[0056] Comparative Example 5

[0057] The difference between this comparative example and Example 4 lies in the different addition amount of sulfamic acid in this comparative example. Specifically for co-precipitation: add a 25% sulfamic acid solution with a mass fraction of 60% to the leaching solution, the reaction temperature is 45 °C, the stirring speed is 450 rpm, and the reaction time is 60 min. At this time, a ternary cathode material precursor and a lithium-rich solution can be obtained; the rest is the same as Example 4.

[0058] Comparative Example 6

[0059] The difference between this comparative example and Example 4 lies in the different addition amount of sulfamic acid in this comparative example. Specifically for co-precipitation: add a 25% sulfamic acid solution with a mass fraction of 20% to the leaching solution, the reaction temperature is 45 °C, the stirring speed is 450 rpm, and the reaction time is 60 min. At this time, a ternary cathode material precursor and a lithium-rich solution can be obtained; the rest is the same as Example 4.

[0060] Comparative Example 7

[0061] The difference between this comparative example and Example 4 is that the 5'-xanthylic acid disodium in this comparative example is sodium carbonate; the rest is the same as Example 4.

[0062] Comparative Example 8

[0063] The difference between this comparative example and Example 4 lies in the different addition amount of the 5'-xanthylic acid disodium solution in this comparative example. Specifically for lithium precipitation: further precipitate the lithium-rich solution. Add a NaOH solution to the lithium-rich solution to adjust the solution pH to 10, add a 39% 5'-xanthylic acid disodium solution with a mass fraction of 50%, and react at 92 °C with a stirring speed of 300 rpm for 2 h to obtain a precipitate; the rest is the same as Example 4.

[0064] Comparative Example 9

[0065] The difference between this comparative example and Example 4 lies in the different addition amount of the 5'-xanthylic acid disodium solution in this comparative example. Specifically for lithium precipitation: further precipitate the lithium-rich solution. Add a NaOH solution to the lithium-rich solution to adjust the solution pH to 10, add a 39% 5'-xanthylic acid disodium solution with a mass fraction of 20%, and react at 92 °C with a stirring speed of 300 rpm for 2 h to obtain a precipitate; the rest is the same as Example 4.

[0066] Comparative Example 10

[0067] The difference between this comparative example and Example 4 is that one-step precipitation method is used for precipitation. Specifically: add a 25% ammonium oxalate solution with a mass fraction of 40% to the leaching solution, the reaction temperature is 45 °C, the stirring speed is 450 rpm, and the reaction time is 60 min. At this time, a precipitate can be obtained.

[0068] Experiment 2: Total recovery rate

[0069] Measure the content of valuable metals in the waste lithium batteries before treatment and the content of valuable metals obtained after the above treatment to obtain the total recovery rate, as shown in Table 2 below.

[0070] Table 2

[0071]

Claims

1. A process for the selective extraction of valuable metals from lithium batteries, including discharging, separating the cathode material, heat treatment, acid leaching, coprecipitation, and lithium precipitation, characterized in that, The process is as follows: Battery discharging: Discharge the waste battery with a 5% NaCl solution by mass fraction for 24 h, and mechanically separate the battery core to obtain the positive electrode, negative electrode, and separator; Separation of positive electrode material: Cut the positive electrode plate into small pieces of 1x1 cm, and soak them in a 15% NMP solution, stir at 240 w with ultrasonic waves at 100 °C for 1 h to accelerate the separation of the positive electrode material and dissolve the PVDF binder; Heat treatment: After the separated positive electrode material is calcined in a muffle furnace at 700 °C for 2 h, grind it and reserve it as the raw material for acidolysis; The acid leaching treatment is as follows: Add sulfuric acid with a mass fraction of 10% to the ground positive electrode raw material, the ratio of sulfuric acid to the reducing agent is 8:2 - 3, the solid-liquid ratio is 30 g / L, the reaction temperature is 55 - 60 °C, the time is 60 min, the stirring speed is controlled at 400 - 600 rpm, filter after leaching to obtain the filtrate; The reducing agent is a gallocatechin solution with a mass fraction of 40 - 50%; The co-precipitation treatment is to add a 30 - 50% co-precipitating agent to the leaching solution, the reaction temperature is 40 - 50 °C, the stirring speed is 400 - 500 rpm, and the reaction time is 60 min. At this time, the ternary positive electrode material precursor and the lithium-rich solution can be obtained; The co-precipitating agent is a hydroxylamine sulfonic acid solution with a mass fraction of 20 - 30%.

2. The process for selective extraction of valuable metals from a lithium battery as described in claim 1, characterized in that, The lithium precipitation process is as follows: Further precipitate the lithium-rich solution after acid leaching and co-precipitation treatment. Add NaOH solution to the lithium-rich solution to adjust the solution pH to 9 - 11, add a 30 - 40% lithium precipitating agent, and react at 90 - 95 °C with a stirring speed of 200 - 400 rpm for 2 h to obtain the precipitate.

3. The process for selective extraction of valuable metals from lithium batteries as described in claim 2, characterized in that: The lithium precipitating agent is a 5'-inosinic acid disodium solution with a mass fraction of 32 - 46%.

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