Process for selectively extracting valuable metal of lithium battery

Abstract

The invention relates to a process for selectively extracting valuable metals in a lithium battery, which comprises the steps of discharging, positive electrode material separation, heat treatment, acid leaching, coprecipitation, lithium precipitation and the like, and realizes efficient recovery and utilization of the valuable metals in the waste lithium battery.

Description

Technical Field

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

[0002] LiFePO4, the positive electrode material of lithium batteries, is widely used in the fields of mobile phones, electric vehicles, etc. 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 scrap volume of lithium iron phosphate batteries. Batteries contain toxic chemicals and high-value metals and must be recycled to promote environmental protection and sustainable development. The pretreatment process of waste lithium batteries mainly includes classification, discharge, disassembly, crushing, separation and removal of organic binders to finally obtain black powder rich in positive electrode materials. Therefore, the present invention improves the recovery of various valuable metals by studying the treatment of waste lithium batteries such as acid leaching.

[0003] In the traditional wet leaching, the acid leaching process of the positive electrode material often adopts the acid + reducing agent leaching system. H2O2 is currently widely used as a reducing agent, which has the advantages of being green, environmentally friendly and pollution-free, but there are problems such as low thermal decomposition temperature and inconvenient transportation and storage. Recently, some researchers have begun to try to use natural products as reducing agents. Substances with reducing groups such as macadamia nut shells, orange peels, and starch are also often used as reducing agents in the acid leaching process. These reducing agents are more environmentally friendly, safe and convenient to transport or store. There are studies that use the natural product tea polyphenols as a reducing agent to construct a sulfuric acid-tea polyphenols leaching system, achieving highly selective recovery of various metal ions. Therefore, selecting a natural and efficient reducing agent is the research focus of the present invention.

[0004] The recovery and extraction of various valuable metals in waste lithium batteries by step-by-step precipitation treatment under different process conditions can effectively improve the recovery efficiency, reduce environmental pollution, and promote the recycling of resources. Therefore, how to efficiently recover valuable metals by step-by-step precipitation is the research focus of the present invention. Summary of the invention

[0005] The object of the present invention is to provide a process for selectively extracting valuable metals from lithium batteries.

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

[0007] A process for selectively extracting valuable metals from lithium batteries, comprising discharge, separation of positive electrode materials, heat treatment, acid leaching, coprecipitation, and lithium precipitation, characterized in that: the acid leaching treatment comprises: adding 10% sulfuric acid by mass to the ground positive electrode raw material, the ratio of sulfuric acid to reducing agent is 8:2-3, the solid-liquid ratio is 30g / L, the reaction temperature is 55-60°C, the time is 60min, the stirring speed is controlled to be 400-600rpm, filtering after leaching to obtain a filtrate;

[0008] The reducing agent is a gallol catechin solution with a mass fraction of 40-50%.

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

[0010] The coprecipitant is a hydroxylamine sulfonic acid solution with a mass fraction of 20-30%.

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

[0012] Battery discharge: Use a 5% by mass NaCl solution to discharge the used batteries for 24 hours, and mechanically separate the battery cells to obtain the positive electrode, negative electrode and separator;

[0013] Positive electrode material separation: The positive electrode sheet was cut into small pieces of 1x1 cm and immersed in 15% NMP solution at 100°C with ultrasonic stirring at 240w for 1h to accelerate the separation of the positive electrode material and dissolve the PVDF binder;

[0014] Heat treatment: The separated positive electrode material is calcined in a muffle furnace at 700°C for 2h, and then ground and used as raw material for acid hydrolysis;

[0015] Lithium precipitation: The lithium-rich solution after acid leaching and co-precipitation treatment is further precipitated, NaOH solution is added to the lithium-rich solution to adjust the solution pH to 9-11, 30-40% lithium precipitation agent is added, and the reaction is carried out at 90-95° C. and the stirring speed is 200-400 rpm for 2 hours to obtain a precipitate.

[0016] The lithium precipitation agent is a 5'-xanthosyl disodium solution with a mass fraction of 32-46%.

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

[0018] 1. The present invention realizes the efficient recovery and utilization of valuable metals in waste lithium batteries through the steps of discharge, separation of positive electrode materials, heat treatment, acid leaching, co-precipitation, lithium precipitation, etc., improves the extraction and leaching of valuable metals by adopting natural reducing agents combined with acid leaching in a green and environmentally friendly manner, and maximizes the precipitation recovery of valuable metals by a step-by-step precipitation method, thereby reducing the loss of valuable metals.

[0019] 2. Among them, the phenolic hydroxyl group of gallic catechin 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 gallic catechin can react with these metal ions, reducing them to low-valent metals, promoting their dissolution and leaching. During the acid leaching process, sulfuric acid provides an acidic environment that is conducive to the dissolution of metal compounds, while gallic catechin promotes the dissolution of metals through reduction and improves the leaching efficiency. The reaction process is more exothermic, increasing the frequency of collisions between molecules, thereby accelerating the reaction.

[0020] 3. Compared with tea polyphenols, gallol catechins, as a reducing agent in the recycling of waste batteries, have higher reducing ability, better stability and selectivity, and lower environmental harm. At the same time, they also have certain advantages in cost and raw material supply. They can significantly improve the efficiency and environmental protection of waste lithium battery recycling, reduce the discharge of harmful wastewater, and reduce the cost of wet leaching.

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

[0022] 5. Hydroxylamine sulfonic acid can be added over a wide pH range, while other types of reducing agents are more sensitive to pH changes. Oxalate exhibits 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 work effectively under a wider range of acid and alkaline conditions and has greater adaptability. The rate of reduction of hydroxylamine in hydroxylamine sulfonic acid is relatively mild, which can control the particle size distribution during the precipitation process. A more uniform reduction reaction can ensure that the particle size of the precipitate is small and evenly distributed.

[0023] 6. In lithium-rich solutions, there is usually a certain salt effect. The salt effect enhances the solvation effect and weakens the interaction between ions, resulting in the inability of ions in the solution to effectively contact and react during the reaction. The phosphate group in disodium xanthate has a strong affinity with 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 xanthate can effectively form a complex with lithium ions, reduce the influence of ionic strength in the solution, thereby overcoming the inhibitory effect of the salt effect and promoting the precipitation of lithium phosphate. Disodium xanthate not only improves the reaction efficiency of lithium ions and phosphate ions through the phosphate group in its structure, but its purine ring part can also play a certain structural stabilizing role 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 DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the examples. The waste lithium battery is a nickel cobalt manganese oxide lithium battery (NCM523 type), and the waste battery is discharged for 24 hours using a 5% mass fraction NaCl solution, and the battery core is mechanically separated to obtain a positive electrode, a negative electrode and a separator; the positive electrode sheet is cut into small pieces of 1x1cm, and immersed in a 15% NMP solution and stirred at 100°C and 240w for 1 hour 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 hours, and then ground as a raw material for acid hydrolysis; the following test is carried out.

[0025] Example 1

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

[0027] Example 2

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

[0029] Example 3

[0030] Acid leaching treatment: add 10% sulfuric acid by mass to the ground positive electrode raw material, the reducing agent is a 50% gallic catechin solution by mass, the ratio of sulfuric acid to the reducing agent is 8:3, the solid-liquid ratio is 30g / L, the reaction temperature is 55°C, the time is 60min, the stirring speed is controlled at 600rpm, and the leaching is filtered to obtain the filtrate;

[0031] Comparative Example 1

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

[0033] Comparative Example 2

[0034] The difference between this comparative example and Example 1 is that the amount of gallic acid catechin solution added is different. The specific acid leaching treatment is as follows: sulfuric acid with a mass fraction of 10% is added to the ground positive electrode raw material, the reducing agent is a gallic acid catechin solution with a mass fraction of 45%, the ratio of sulfuric acid to the reducing agent is 8:4, the solid-liquid ratio is 30g / L, the reaction temperature is 58°C, the time is 60min, the stirring speed is controlled to 500rpm, and the leaching is filtered to obtain a filtrate; the rest is the same as Example 1.

[0035] Comparative Example 3

[0036] The difference between this comparative example and Example 1 is that the amount of gallic acid catechin solution added is different. The specific acid leaching treatment is as follows: sulfuric acid with a mass fraction of 10% is added to the ground positive electrode raw material, the reducing agent is a gallic acid catechin solution with a mass fraction of 45%, the ratio of sulfuric acid to the reducing agent is 8:1, the solid-liquid ratio is 30g / L, the reaction temperature is 58°C, the time is 60min, the stirring speed is controlled to 500rpm, and the leaching is filtered to obtain a filtrate; the rest is the same as Example 1.

[0037] Test 1: Leaching rate

[0038] The filtrate after acid leaching is taken to detect the metal ion concentration and the leaching rate (ξ).

[0039]

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

[0041] The results are shown in Table 1.

[0042] Table 1

[0043] sample Li leaching rate (%) Ni leaching rate (%) Co leaching rate (%) 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 implementation modes are all carried out on the basis of Example 1.

[0045] Example 4

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

[0047] Lithium precipitation: The lithium-rich solution is further precipitated by adding NaOH solution to the lithium-rich solution to adjust the solution pH to 10, adding 35% of 39% 5'-xanthoglobulin disodium solution, and reacting at 92° C. with a stirring speed of 300 rpm for 2 hours to obtain a precipitate.

[0048] Example 5

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

[0050] Lithium precipitation: The lithium-rich solution is further precipitated by adding NaOH solution to the lithium-rich solution to adjust the solution pH to 11, adding 30% of 46% 5'-xanthoglobulin disodium solution, reacting at 90° C. with a stirring speed of 400 rpm for 2 h to obtain a precipitate.

[0051] Example 6

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

[0053] Lithium precipitation: The lithium-rich solution is further precipitated by adding NaOH solution to the lithium-rich solution to adjust the solution pH to 11, adding 40% of 32% 5'-xanthoglobulin disodium solution, reacting 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 is that the amount of hydroxylamine sulfonic acid added in this comparative example is different. Specifically, the co-precipitation is as follows: 60% of a 25% hydroxylamine sulfonic acid solution by mass is added to the leachate, the reaction temperature is 45°C, the stirring speed is 450rpm, and the reaction time is 60min. At this time, a ternary positive electrode 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 is that the amount of hydroxylamine sulfonic acid added in this comparative example is different. Specifically, the co-precipitation is as follows: 20% of a 25% hydroxylamine sulfonic acid solution by mass is added to the leachate, the reaction temperature is 45°C, the stirring speed is 450rpm, and the reaction time is 60min. At this time, a ternary positive electrode 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'-xanthoglobulin 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 is that the amount of 5'-xanthate disodium solution added in this comparative example is different. Specifically, lithium precipitation: the lithium-rich solution is further precipitated, NaOH solution is added to the lithium-rich solution to adjust the solution pH to 10, 50% of 39% 5'-xanthate disodium solution is added, and the reaction is carried out 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 is that the amount of 5'-xanthate disodium solution added in this comparative example is different. Specifically, lithium precipitation: the lithium-rich solution is further precipitated by adding NaOH solution to the lithium-rich solution to adjust the solution pH to 10, adding 20% ​​of 39% 5'-xanthate disodium solution, and reacting 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 a one-step precipitation method is used for precipitation, specifically: 40% of a 25% ammonium oxalate solution by mass is added to the leachate, the reaction temperature is 45°C, the stirring speed is 450rpm, and the reaction time is 60min, at which time a precipitate can be obtained.

[0068] Test 2: Total recovery

[0069] The valuable metal content in the waste lithium batteries before treatment and the valuable metal content after the above treatment were measured to obtain the total recovery rate, as shown in Table 2 below.

[0070] Table 2

[0071]

Claims

1. A process for selective extraction of valuable metals from lithium batteries, comprising discharge, separation of positive electrode materials, heat treatment, acid leaching, coprecipitation, and lithium precipitation, characterized in that: The acid leaching treatment is as follows: adding 10% sulfuric acid by mass to the ground positive electrode raw material, the ratio of sulfuric acid to reducing agent is 8:2-3, the solid-liquid ratio is 30g / L, the reaction temperature is 55-60°C, the time is 60min, the stirring speed is controlled to be 400-600rpm, and filtering after leaching to obtain a filtrate; The reducing agent is a gallol catechin solution with a mass fraction of 40-50%.

2. The process for selectively extracting valuable metals from lithium batteries according to claim 1, characterized in that: The coprecipitation treatment is to add 30-50% of the coprecipitant to the leaching solution, the reaction temperature is 40-50°C, the stirring speed is 400-500rpm, and the reaction time is 60min, at which time a ternary cathode material precursor and a lithium-rich solution can be obtained.

3. The process for selectively extracting valuable metals from lithium batteries according to claim 2, characterized in that: The coprecipitant is a hydroxylamine sulfonic acid solution with a mass fraction of 20-30%.

4. The process for selectively extracting valuable metals from lithium batteries according to claim 1, characterized in that: Proceed as follows: Battery discharge: Use a 5% by mass NaCl solution to discharge the used batteries for 24 hours, and mechanically separate the battery cells to obtain the positive electrode, negative electrode and separator; Positive electrode material separation: The positive electrode sheet was cut into small pieces of 1x1cm and immersed in 15% NMP solution at 100℃ and ultrasonically stirred at 240w for 1h to accelerate the separation of the positive electrode material and dissolve the PVDF binder; Heat treatment: The separated positive electrode material is calcined in a muffle furnace at 700°C for 2h, and then ground and used as raw material for acid hydrolysis; Lithium precipitation: The lithium-rich solution after acid leaching and co-precipitation treatment is further precipitated, NaOH solution is added to the lithium-rich solution to adjust the solution pH to 9-11, 30-40% of lithium precipitation agent is added, and the reaction is carried out at 90-95°C and the stirring speed is 200-400rpm for 2h to obtain a precipitate.

5. The process for selectively extracting valuable metals from lithium batteries according to claim 4, characterized in that: The lithium precipitation agent is a 5'-xanthoglobulin disodium solution with a mass fraction of 32-46%.

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