Method for recovering valuable metals

Abstract

This application discloses a method for recovering valuable metals. The method includes: a mixing step, in which a material containing valuable metals to be recovered, acid, and a reducing agent are mixed to obtain a mixed slurry; a roasting step, in which the mixed slurry is roasted to obtain a roasted product; and a leaching step, in which the roasted product and a leaching agent are mixed and leached, and solid-liquid separation is performed to obtain a lithium-containing leachate. The reducing agent includes a first regenerated reducing agent obtained by activating a deactivated reducing agent with a first acidic tail gas generated during the mixing of the material containing valuable metals and acid, and / or a second regenerated reducing agent obtained by activating a deactivated reducing agent with a second acidic tail gas generated during the roasting step. This application cleverly utilizes the acidic tail gas generated during the mixing and roasting steps to activate the deactivated reducing agent to obtain a regenerated reducing agent, which is then fed into the front end and mixed with the material containing valuable metals to be recovered and acid, thereby accelerating lithium extraction during the roasting process and increasing the lithium yield.

Description

Technical Field

[0001] This application relates to the field of valuable metal recycling technology, and more specifically, to a method for recycling valuable metals. Background Technology

[0002] With the rapid development of technology, valuable metals have become closely intertwined with human society. For example, personal digital products such as laptops, mobile phones, and Bluetooth headsets, as well as electric vehicles, electric bicycles, electric ships, and electric rail vehicles, contain abundant valuable metal elements. In order to conserve valuable metal resources, it is urgent to recycle valuable metals from waste products.

[0003] However, in related technologies, the cost of recycling valuable metals is not only high, but also the loss of some metals is significant. Summary of the Invention

[0004] This application provides a method for recycling valuable metals, which can reduce the recycling cost of valuable metals and reduce lithium loss.

[0005] The technical problem solved by this application is achieved by the following technical solution.

[0006] This application provides a method for recycling valuable metals, including:

[0007] The mixing process involves mixing the material to be recycled containing valuable metals, acid, and reducing agent to obtain a mixed slurry.

[0008] The roasting process involves roasting the mixed slurry to obtain the roasted product.

[0009] In the leaching process, the roasted product and the leaching agent are mixed and leached, and solid-liquid separation is performed to obtain a lithium-containing leachate.

[0010] The reducing agent includes a first regenerated reducing agent obtained by activating the deactivated reducing agent with the first acidic tail gas generated during the mixing process of the material to be recycled containing valence metals and acid, and / or a second regenerated reducing agent obtained by activating the deactivated reducing agent with the second acidic tail gas generated during the roasting process.

[0011] In some embodiments of this application, the mass ratio of the recyclable material containing valence metal, acid, and reducing agent is 1:(0.4-1.5):(0.05-0.2).

[0012] In some embodiments of this application, the recyclable material containing valuable metals includes battery recyclables.

[0013] In some embodiments of this application, the acid includes inorganic acids.

[0014] In some embodiments of this application, the acid includes at least one of concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.

[0015] In some embodiments of this application, the acid includes concentrated sulfuric acid.

[0016] In some embodiments of this application, the reducing agent includes a first acidic tail gas generated during the mixing of the recyclable material containing valence metals with acid to activate deactivated activated carbon to obtain a first regenerated reducing agent, and / or a second acidic tail gas generated during the roasting process to activate deactivated activated carbon to obtain a second regenerated activated carbon.

[0017] In some embodiments of this application, the calcination temperature is 450°C-850°C.

[0018] In some embodiments of this application, the second regenerated reducing agent obtained by activating the deactivated reducing agent with the second acidic tail gas generated in the roasting process includes:

[0019] The cooling step cools the second acidic tail gas to 50℃-400℃;

[0020] In the activation step, the cooled second acidic tail gas is contacted with the deactivated reducing agent to activate the deactivated reducing agent and obtain the second regenerated reducing agent.

[0021] In some embodiments of this application, the calcination process is carried out under a nitrogen atmosphere, with a nitrogen introduction rate of 4 Nm. 3 / h-6Nm 3 / h.

[0022] In some embodiments of this application, the leaching process includes:

[0023] The crushing step involves crushing the roasted product to make the particle size of the roasted product less than or equal to 0.35 mm.

[0024] In the leaching step, the crushed roasted product and the leaching agent are mixed and leached, and the solid and liquid are separated to obtain a lithium-containing leachate.

[0025] In some embodiments of this application, the leaching agent includes water, and the mass ratio of the calcined product to water is 1:(2-10).

[0026] This application has the following beneficial effects:

[0027] This application provides a method for recovering valuable metals. Residual acid in the first acidic tail gas generated during the mixing process and / or the second acidic tail gas generated during the roasting process activates a deactivated reducing agent, partially restoring its reducing capacity to obtain a regenerated reducing agent. This regenerated reducing agent is then returned to the upstream stage and mixed with the material to be recovered containing valuable metals and acid. This not only allows some of the valuable metal-containing powder entrained in the tail gas to be returned to the mixing process, reducing the loss of valuable metals, but also enables the regenerated reducing agent to create a reducing atmosphere during the roasting process, which facilitates the leaching of lithium in the leaching process. Furthermore, the regeneration of the deactivated reducing agent reduces recovery costs and lowers the acidic gas content in the tail gas, significantly reducing downstream tail gas treatment costs and further lowering the recovery cost of valuable metals, while also reducing environmental pollution from the emitted tail gas. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This application illustrates flowcharts for recycling valuable metals according to some embodiments;

[0030] Figure 2 A flowchart illustrating the recycling of valuable metals provided in other embodiments of this application is shown. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0032] Currently, the recovery of valuable metals mainly involves two processes: one is the wet recovery process, which uses high acid to directly leach the metals from the material containing valuable metals, and then selectively extracts the corresponding products; the other is the pyrometallurgical lithium extraction process, which uses processes such as roasting to extract lithium metal first, and then recovers other valuable metals. The wet recovery process has a low lithium metal yield, only about 85%, and the recovery process is lengthy. The pyrometallurgical lithium extraction process, which extracts lithium metal first and then recovers other valuable metals, can significantly improve the lithium metal yield compared to the wet process, and is therefore adopted by most companies. However, the inventors found that the amount of acid added in the pyrometallurgical lithium extraction process is often excessive. Excessive acid increases the cost of lithium recovery and also results in a large amount of residual acid in the exhaust gas, increasing the cost of exhaust gas treatment and further increasing the cost of lithium recovery. Moreover, during the mixing of the material containing valuable metals with acid, some powder containing valuable metals enters the exhaust gas, causing some metal loss and thus reducing the lithium yield.

[0033] In view of this, this application provides a method for recycling valuable metals, which can reduce the recycling cost of valuable metals and reduce lithium loss.

[0034] The following is a detailed description of a method for recycling valuable metals provided by the embodiments of this application.

[0035] Please see Figure 1 As shown, this application provides a method for recycling valuable metals, including:

[0036] S100, Mixing process: The material to be recycled containing valuable metals, acid and reducing agent are mixed to obtain a mixed slurry;

[0037] S200, calcination process, calcining the mixed slurry to obtain the calcined product;

[0038] S300, Leaching process: The roasted product and leaching agent are mixed and leached, and solid-liquid separation is performed to obtain lithium-containing leachate;

[0039] The reducing agent includes a first regenerated reducing agent obtained by activating the deactivated reducing agent with the first acidic tail gas generated during the mixing process of the material to be recycled containing valence metals and acid, and / or a second regenerated reducing agent obtained by activating the deactivated reducing agent with the second acidic tail gas generated during the roasting process.

[0040] The method for recovering valuable metals provided in this application utilizes residual acid in the first acidic tail gas generated in the mixing process and / or the second acidic tail gas generated in the roasting process to activate a deactivated reducing agent, thereby restoring some of its reducing capacity to obtain a regenerated reducing agent. This regenerated reducing agent is then returned to the front end and mixed with the material to be recovered containing valuable metals and acid. This not only allows some of the valuable metal powder mixed in the tail gas to be returned to the mixing process to reduce the loss of valuable metals (e.g., lithium), but also enables the regenerated reducing agent to create a reducing atmosphere during the roasting process, which helps the leaching of lithium in the leaching process. The regeneration of the deactivated reducing agent can reduce the recovery cost and also reduce the acidic gas content in the tail gas, which can greatly reduce the cost of back-end tail gas treatment, thereby further reducing the recovery cost of valuable metals and reducing the environmental pollution caused by the discharged tail gas.

[0041] In addition, the regeneration of the deactivated reducing agent can reduce the amount of acidic exhaust gas to be treated, reduce the corrosion of equipment by acidic exhaust gas, and the regenerated reducing agent can also contribute some heat during the roasting process, reducing the power consumption during the roasting process.

[0042] In the mixing process of the embodiments of this application, the mass ratio of the recyclable material containing valence metal, acid and reducing agent is controlled within a suitable range, which can help improve the lithium leaching rate.

[0043] In some alternative embodiments, the mass ratio of the recyclable material containing valence metals, acid, and reducing agent is 1:(0.4-1.5):(0.05-0.2).

[0044] Optionally, the mass ratio of the recyclable material containing valence metals, acid, and reducing agent can be, but is not limited to, 1:0.4:0.05, 1:0.5:0.05, 1:0.6:0.06, 1:0.7:0.08, 1:1.0:0.10, 1:1.2:0.15, 1:1.4:0.18, 1:1.5:0.2, or 1:(0.4-1.5):(0.05-0.2). Controlling the appropriate mass ratio of the recyclable material containing valence metals, acid, and reducing agent can convert high-valence metal elements in the recyclable material into low-valence metal oxides. In this process, soluble lithium oxide contacts the acid and forms a salt on the solid surface, thereby improving the lithium leaching rate.

[0045] In some optional implementations, the mixing time of the recyclable material containing valence metals, acid, and reducing agent is 5 min to 45 min.

[0046] Optionally, the mixing time of the recyclable material containing valuable metals, acid, and reducing agent can be, but is not limited to, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, or any value between 5 min and 45 min, or any two values ​​between 5 min and 45 min.

[0047] In this application, the recyclable material containing valuable metals can refer to materials containing valuable metals that are sent to a recycling plant for processing and recycling. It is understood that various methods are used to collect the recyclable material containing valuable metals and deliver it to a processing and recycling facility so that the recovered lithium-containing material can be used to generate new materials or new products.

[0048] In some optional embodiments, the recyclable material containing valuable metals includes battery recyclables. Further, the battery recyclables include lithium-ion battery recyclables, which refer to primary or secondary batteries containing lithium. Exemplary examples include lithium-ion secondary batteries, lithium-sulfur secondary batteries, sodium-ion secondary batteries, and lithium metal primary batteries. In some examples, the recyclable material containing valuable metals includes waste lithium-ion secondary battery recyclables. The positive electrode in these recyclables comprises a positive electrode current collector and a positive electrode active material. The positive electrode current collector can be a metal foil such as aluminum, copper, or nickel, and the positive electrode active material can include valuable metals such as nickel (Ni), cobalt (Co), manganese (Mn), and lithium (Li). In some specific examples, waste lithium-ion battery recyclables can be a mixture containing valuable metals such as Ni, Co, Mn, and Li, and carbon powder, obtained through processes such as dismantling, crushing, screening, pyrolysis, and sorting. This recyclable material can also be referred to as battery black powder. Furthermore, in some examples, the mass percentages of each component in the battery black powder are as follows: Ni 15%-25%, Co 2%-12%, Mn 6%-15%, Fe 0.5%-3%, Mg 0.01%-0.5%, Si 0.01%-0.5%, Zn 0.001%-0.05%, S 0.1%-1%, Cu 0.5%-3%, Al 1%-12%, and Li 3%-6%.

[0049] In some alternative implementations, the volume of the material to be recycled containing valuable metals is large, and it needs to be crushed to facilitate the leaching and recovery of the metals.

[0050] In some alternative embodiments, the particle size of the material to be recycled containing valence metals is ≤0.35 mm. When the particle size of the lithium-containing material to be recycled is within the above range, the surface area of ​​the material to be recycled containing valence metals can be increased, which can provide a larger contact area with the acid solution and more metal exposure, thereby utilizing roasting reduction and leaching.

[0051] For example, the particle size of the material to be recycled containing valuable metals may be, but is not limited to, any value between 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm or ≤0.35 mm, or a range of any two values ​​between ≤0.35 mm.

[0052] In the embodiments of this application, a suitable acid can facilitate the leaching of lithium while reducing the leaching of other metals, thereby reducing metal impurities in the lithium-containing leachate and increasing the purity of lithium in the lithium leachate.

[0053] In some alternative embodiments, the acid includes an inorganic acid that can rapidly leach lithium ions from a solid.

[0054] In some alternative embodiments, the acid includes at least one of concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.

[0055] In some alternative embodiments, the acid includes concentrated sulfuric acid, which here refers to sulfuric acid with a mass fraction of 98% or more in the solution. Concentrated sulfuric acid can reduce the corrosion of equipment during the mixing process and reduce the agglomeration of recyclable materials containing valuable metals, thereby improving lithium leaching.

[0056] In this application, the deactivated reducing agent refers to a solid reducing agent that has lost its reducing properties and is regenerable. Activation refers to the process of restoring at least part of the deactivated reducing agent to its activity, i.e., a regeneration process. If these deactivated reducing agents accumulate over a long period, it will lead to the generation of a large amount of solid waste. For example, in metallurgy and other fields, the separation of metals from solutions typically uses organic extractants to obtain a solution of the target metal. The total organic carbon (TOC) in this solution generally exceeds the standard. Therefore, activated carbon is needed to remove TOC from nickel / cobalt / manganese sulfate solutions. This process generates a large amount of waste activated carbon, which is generally hazardous waste and has high treatment costs. The method provided in this application allows for the regeneration of the deactivated reducing agent and its further utilization in creating a reducing atmosphere during the roasting process, which facilitates lithium leaching in the leaching process. Furthermore, it can reduce the lithium content in the acid gas in the exhaust gas, thereby reducing the exhaust gas treatment cost and further reducing the lithium recovery cost.

[0057] In some alternative embodiments, the reducing agent may include a first regenerated activated carbon obtained by activating deactivated activated carbon with a first acidic tail gas generated during the mixing of the recyclable material containing valence metals and acid, and / or a second regenerated activated carbon obtained by activating deactivated activated carbon with a second acidic tail gas generated during the calcination process.

[0058] In the above embodiments, since the recyclable material containing valence metals may be carried away by the tail gas during the mixing and roasting processes, the first acidic tail gas generated in the mixing process can be used to activate the deactivated activated carbon to obtain the first regenerated activated carbon, and / or the second acidic tail gas generated in the roasting process can be used to activate the deactivated activated carbon to obtain the second regenerated activated carbon. This not only utilizes the acidic gas in the tail gas to activate the deactivated activated carbon to obtain regenerated activated carbon, but also allows the regenerated activated carbon to adsorb at least a portion of the recyclable material containing valence metals carried in the tail gas into its pores, thus anchoring and dispersing the recyclable material containing valence metals, reducing the loss of the recyclable material containing valence metals, and thereby improving the lithium recovery rate. Furthermore, since roasting is carried out in an inert gas atmosphere such as nitrogen, a reducing atmosphere can be created during the roasting process of the regenerated activated carbon, reducing the nitrogen introduction rate.

[0059] In some alternative embodiments of this application, the co-mixing of the recyclable material containing valence metals, concentrated sulfuric acid, and regenerated activated carbon can help reduce the agglomeration of the recyclable material and improve lithium leaching.

[0060] In some examples, a mixed slurry containing valuable metals, concentrated sulfuric acid, and regenerated activated carbon is mixed and then roasted. This process converts the insoluble lithium carbonate produced by roasting into water-soluble lithium sulfate, which can then be leached to obtain a lithium sulfate leachate, thus achieving efficient lithium extraction.

[0061] In some alternative implementations, the calcination temperature can be 450°C-850°C.

[0062] For example, the calcination temperature can be, but is not limited to, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or any value between 450°C and 850°C, or a range consisting of any two values ​​between 450°C and 850°C. Calcination temperatures within the above ranges can facilitate lithium leaching, thereby improving lithium recovery rates.

[0063] In some alternative implementations, the calcination time can be 1-4 hours.

[0064] For example, the calcination time can be, but is not limited to, any value between 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, or any value between 1h and 4h, or a range of any two values ​​between 1h and 4h.

[0065] In some optional embodiments, the second regenerated reducing agent obtained by activating the deactivated reducing agent with the second acidic tail gas generated in the roasting process includes:

[0066] The cooling step cools the second acidic tail gas to 50℃-400℃;

[0067] In the activation step, the cooled second acidic tail gas is contacted with the deactivated reducing agent to activate the deactivated reducing agent and obtain the regenerated reducing agent.

[0068] For example, the second acidic tail gas may be cooled to, but is not limited to, any value between 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, or any value between 50°C and 400°C, or any two values ​​between 50°C and 400°C.

[0069] In the roasting process of this application, the roasting treatment is carried out under an inert atmosphere, which helps to reduce wear and tear on the roasting equipment. Furthermore, introducing inert gas at an appropriate rate to create an inert atmosphere reduces the oxygen content in the roasting equipment, further reducing wear and tear on the equipment.

[0070] In some alternative embodiments, the calcination process is carried out under a nitrogen atmosphere, with a nitrogen introduction rate of 4 Nm. 3 / h-6Nm 3 / h. A nitrogen gas introduction rate within the above range enables the calcination equipment to calcine the mixed slurry in the presence of a small amount of oxygen, further reducing equipment wear and tear while also facilitating lithium leaching.

[0071] For example, the nitrogen introduction rate can be, but is not limited to, 4 Nm. 3 / h, 4.5Nm 3 / h、5Nm 3 / h, 5.5Nm 3 / h、6Nm 3 / h or 4Nm 3 / h-6Nm 3 Any value between / h or 4Nm 3 / h-6Nm 3 The range of values ​​formed by any two values ​​in / h.

[0072] In some alternative implementations, nitrogen is introduced during the roasting process to ensure that the oxygen content inside the equipment is ≤10%.

[0073] Please see Figure 2 As shown, in some optional embodiments, the leaching process in S300 includes:

[0074] S310, Crushing step: The roasted product is crushed so that the particle size of the roasted product is less than or equal to 0.35 mm.

[0075] S320, Leaching step: The crushed roasted product and leaching agent are mixed and leached, and solid-liquid separation is performed to obtain lithium-containing leachate.

[0076] For example, the particle size of the calcined product after ball milling can be, but is not limited to, any value between 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, or ≤0.35 mm, or any two values ​​within the range of ≤0.35 mm. Grinding and crushing the calcined product before leaching increases the contact area between the calcined product and the leaching agent, making it easier for its lithium-containing compounds to enter the leaching agent and obtain a lithium-containing leachate.

[0077] In some alternative embodiments, the leaching agent comprises water, and the mass ratio of the calcined product to water is 1:(2-10).

[0078] Optionally, the mass ratio of roasted product to water during leaching treatment may be, but is not limited to, any value between 1:2, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or 1:(2-10).

[0079] In some alternative implementations, the leaching treatment time can be 1 hour to 6 hours.

[0080] For example, the leaching time may be, but is not limited to, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or any value between 1h and 6h, or a range of any two values ​​between 1h and 6h.

[0081] In some optional embodiments, the method for recovering valuable metals includes the following steps: battery black powder with a particle size ≤0.35mm, concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon (including first regenerated activated carbon and / or second regenerated activated carbon) are thoroughly mixed at a mass ratio of 1:(0.4-1.5):(0.05-0.2) for 5-45 minutes to obtain a mixed slurry; then, the obtained mixed slurry is calcined at 450-850℃ for 1-4 hours, during which nitrogen is introduced at a rate of 4 Nm. 3 / h-6Nm 3 / h, the oxygen content in the roasting equipment is <10%, and roasting products are obtained; the obtained roasting products are then crushed and ball-milled to a particle size ≤0.15mm to obtain crushed roasting products. The crushed roasting products are mixed with water at a mass ratio of 1:(2-10) and leached. After solid-liquid separation, lithium sulfate leaching solution is obtained. In the above process of recovering valuable metals, the regenerated activated carbon used comes from the first acidic tail gas generated during the mixing of battery black powder and concentrated sulfuric acid to activate the deactivated activated carbon to obtain the first regenerated activated carbon, and / or the second acidic tail gas generated in the roasting process to activate the deactivated activated carbon to obtain the second regenerated activated carbon. When using the residual acid in the second acidic tail gas to activate the deactivated activated carbon, the second acidic tail gas needs to be cooled to 50℃-400℃ before activating the deactivated activated carbon.

[0082] The following embodiments describe the disclosure of this application in more detail. These embodiments are for illustrative purposes only, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents and raw materials used in the embodiments are commercially available or synthesized by conventional methods, as are the instruments used in the embodiments.

[0083] It should be noted that the composition of the recycled materials used in the embodiments of this application is merely exemplary and should not be construed as a limitation on the idea of ​​this application, namely, the recycling of valuable metals such as nickel, cobalt, manganese and lithium in the recycled materials.

[0084] Example 1

[0085] This embodiment provides a method for recycling valuable metals, including:

[0086] Battery black powder with a particle size of 0.33 mm (composition shown in Table 1), concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon were mixed at a mass ratio of 1:0.8:0.1 (200 g, 160 g, 20 g) for 30 min to obtain a mixed slurry.

[0087] The above-mentioned mixed slurry was calcined at 650℃ for 2 hours, with a nitrogen gas introduction rate of 5 Nm during the calcination process. 3 / h, the oxygen content in the calcination equipment is 8.7%, and 226g of calcined product is obtained.

[0088] The calcined product was crushed and ball-milled to a particle size of 0.12 mm.

[0089] The calcined product after ball milling was soaked in water for 2 hours, and then filtered to obtain a lithium sulfate solution. The mass ratio of water to the ball-milled calcined product was 5:1. The resulting lithium sulfate solution had a volume of 956 mL and a lithium content of 7.83 g / L. The lithium recovery rate in the lithium sulfate leaching section from the battery black powder was 98.49%, where lithium recovery rate = lithium sulfate solution volume × lithium content / (mass of battery black powder × lithium content in battery black powder).

[0090] Table 1 Specific components of battery black powder

[0091] raw material Ni Co Mn Fe Mg Si Zn S Cu Al Li Element% 16.28 7.63 8.6 1.2 0.2 0.1 0.02 0.5 0.8 2 3.8

[0092] Example 2

[0093] This embodiment provides a method for recycling valuable metals, including:

[0094] Battery black powder with a particle size of 0.30 mm (composition shown in Table 1), concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon were mixed at a mass ratio of 1:0.5:0.05 (200 g, 100 g, 10 g) for 15 min to obtain a mixed slurry.

[0095] The above-mentioned mixed slurry was calcined at 650℃ for 3 hours, with a nitrogen gas introduction rate of 5.6 Nm during the calcination process. 3 The oxygen content in the calcination equipment was 8.6% at a rate of 1 h, yielding 243g of calcined product.

[0096] The calcined product was crushed and ball-milled to a particle size of 0.123 mm.

[0097] The calcined product after ball milling was soaked in water for 4 hours and then filtered to obtain a lithium sulfate solution, wherein the mass ratio of water to the ball-milled calcined product was 10:1. The resulting lithium sulfate solution had a volume of 2218 mL and a lithium content of 3.16 g / L. The lithium recovery rate from the battery black powder to the lithium sulfate leaching solution was 92.22%.

[0098] Example 3

[0099] This embodiment provides a method for recycling valuable metals, including:

[0100] Battery black powder with a particle size of 0.28 mm (composition shown in Table 1), concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon were mixed at a mass ratio of 1:1.5:0.2 (200 g, 300 g, 40 g) for 25 min to obtain a mixed slurry.

[0101] The above-mentioned mixed slurry was calcined at 450℃ for 4 hours, with a nitrogen gas introduction rate of 4.2 Nm during the calcination process. 3The oxygen content in the calcination equipment was 8.8% at a rate of / h, yielding 309g of calcined product.

[0102] The calcined product was crushed and ball-milled to a particle size of 0.11 mm.

[0103] The calcined product after ball milling was soaked in water for 6 hours and then filtered to obtain a lithium sulfate solution, wherein the mass ratio of water to the calcined product after ball milling was 2:1. The resulting lithium sulfate solution had a volume of 605 mL and a lithium content of 11.85 g / L. The lithium recovery rate in the lithium sulfate leaching section from the battery black powder was 94.33%.

[0104] Example 4

[0105] This embodiment provides a method for recycling valuable metals, including:

[0106] Battery black powder with a particle size of 0.20 mm (composition shown in Table 1), concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon were mixed at a mass ratio of 1:0.7:0.1 (200 g, 140 g, 20 g) for 45 min to obtain a mixed slurry.

[0107] The above-mentioned mixed slurry was calcined at 850℃ for 3 hours, with a nitrogen gas introduction rate of 5.1 Nm during the calcination process. 3 / h, the oxygen content in the calcination equipment is 8.8%, and 208g of calcined product is obtained.

[0108] The calcined product was crushed and ball-milled to a particle size of 0.115 mm.

[0109] The calcined product after ball milling was soaked in water for 1 hour and then filtered to obtain a lithium sulfate solution, wherein the mass ratio of water to the calcined product after ball milling was 5:1. The resulting lithium sulfate solution had a volume of 923 mL and a lithium content of 7.86 g / L. The lithium recovery rate in the lithium sulfate leaching section from the battery black powder was 95.46%.

[0110] Example 5

[0111] This embodiment provides a method for recycling valuable metals, including:

[0112] Battery black powder with a particle size of 0.320 mm (composition shown in Table 1), concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon were mixed at a mass ratio of 1:1:0.05 (200 g, 200 g, 10 g) for 30 min to obtain a mixed slurry.

[0113] The above-mentioned mixed slurry was calcined at 650℃ for 3 hours, with a nitrogen gas introduction rate of 5.8 Nm during the calcination process. 3 / h, the oxygen content in the calcination equipment is 8.5%, and 246g of calcined product is obtained.

[0114] The calcined product was crushed and ball-milled to a particle size of 0.128 mm.

[0115] The calcined product after ball milling was soaked in water for 3 hours and then filtered to obtain a lithium sulfate solution, wherein the mass ratio of water to the ball-milled calcined product was 4:1. The resulting lithium sulfate solution had a volume of 908 mL and a lithium content of 8.18 g / L. The lithium recovery rate from the battery black powder to the lithium sulfate leaching solution was 97.73%.

[0116] Example 6

[0117] This embodiment provides a method for recycling valuable metals, including:

[0118] Battery black powder with a particle size of 0.29 mm (composition shown in Table 1), concentrated sulfuric acid with a mass fraction of 98%, and regenerated activated carbon were mixed at a mass ratio of 1:1.5:0.15 (200 g, 300 g, 30 g) for 30 min to obtain a mixed slurry.

[0119] The above-mentioned mixed slurry was calcined at 650℃ for 2 hours, during which nitrogen gas was introduced at a rate of 4.6 Nm. 3 / h, the oxygen content in the calcination equipment is 8.6%, and 258g of calcined product is obtained.

[0120] The calcined product was crushed and ball-milled to a particle size of 0.116 mm.

[0121] The calcined product after ball milling was soaked in water for 2 hours and then filtered to obtain a lithium sulfate solution, wherein the mass ratio of water to the calcined product after ball milling was 2:1. The resulting lithium sulfate solution had a volume of 458 mL and a lithium content of 16.26 g / L. The lithium recovery rate in the lithium sulfate leaching section from the battery black powder was 97.99%.

[0122] Comparative Example 1

[0123] This comparative example is similar to the method in Example 2, except that: no regenerated activated carbon is added; and the nitrogen gas introduction rate is 6.8 Nm. 3 / h. Then, in the lithium sulfate leaching section, the lithium yield is 80.20%.

[0124] Comparative Example 2

[0125] This comparative example is similar to the method in Example 4, except that: no regenerated activated carbon is added; battery black powder and concentrated sulfuric acid are mixed at a mass ratio of 1:1 (200g, 200g); and the nitrogen gas introduction rate is 7.1 Nm. 3 / h. Then, in the lithium sulfate leaching section, the lithium recovery rate is 95.43%.

[0126] Comparative Example 3

[0127] The method of this comparative example is similar to that of Example 2, except that: concentrated sulfuric acid is mixed with battery black powder for 15 minutes, and then deactivated activated carbon is added and mixed for 15 minutes. When the battery black powder is added to the lithium sulfate leaching solution, the lithium recovery rate is 82.36%.

[0128] Comparative Example 4

[0129] The method of this comparative example is similar to that of Example 2, except that: concentrated sulfuric acid is first mixed with battery black powder for 15 minutes, and then regenerated activated carbon is added and mixed for 15 minutes. When the battery black powder is added to the lithium sulfate leaching solution, the lithium yield is 89.56%.

[0130] Table 2. Nitrogen inlet rate and lithium yield in the examples and comparative examples.

[0131]

[0132]

[0133] As can be seen from Tables 1 and 2, the lithium yields in Examples 1-6 of this application are relatively high, meaning that lithium loss is relatively small. However, in Comparative Examples 1-2, without the addition of regenerated activated carbon, it is necessary to increase the nitrogen gas introduction rate to maintain the reducing atmosphere during calcination in order to obtain a suitable lithium yield. In Comparative Examples 3-4, battery black powder, concentrated sulfuric acid, and carbon were not mixed simultaneously, and deactivated activated carbon (Comparative Example 3) and regenerated activated carbon (Comparative Example 4) were added separately. The lithium yields in Comparative Examples 3-4 were also relatively low compared to the examples, meaning that lithium loss was relatively large.

[0134] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of recovering valuable metals, characterized by, include: In the mixing process, the material to be recycled containing valence metals, acid, and reducing agent are mixed, wherein the mass ratio of the material to be recycled containing valence metals, the acid, and the reducing agent is 1:0.4-1.5:0.05-0.2, to obtain a mixed slurry; The calcination process is performed under a nitrogen atmosphere at a nitrogen flow rate of 4 Nm 3 / h-6 Nm 3 / h; In the leaching process, the roasted product and the leaching agent are mixed and leached, and solid-liquid separation is performed to obtain a lithium-containing leachate. The acid is concentrated sulfuric acid, and the reducing agent includes a first regenerated activated carbon obtained by activating the deactivated activated carbon with a first acidic tail gas generated during the mixing process of the material to be recovered containing valence metal and the acid, and / or a second regenerated activated carbon obtained by activating the deactivated activated carbon with a second acidic tail gas generated during the roasting process.

2. The method according to claim 1, characterized in that, The recyclable materials containing valuable metals include battery recyclables.

3. The method according to claim 1, characterized in that, The roasting temperature is 450℃-850℃.

4. The method according to claim 3, characterized in that, The second regenerated activated carbon obtained by activating the deactivated activated carbon with the second acidic tail gas generated in the roasting process comprises: The cooling step involves cooling the second acidic tail gas to 50°C-400°C. In the activation step, the cooled second acidic tail gas is contacted with the deactivated activated carbon to activate the deactivated activated carbon and obtain the second regenerated activated carbon.

5. The method according to claim 1, characterized in that, The leaching process includes: The pulverizing step involves crushing the roasted product to reduce the particle size of the roasted product to less than or equal to 0.35 mm. In the leaching step, the crushed roasted product and the leaching agent are mixed and leached, and solid-liquid separation is performed to obtain a lithium-containing leachate.

6. The method according to claim 5, characterized in that, The leaching agent includes water, and the mass ratio of the calcined product to the water is 1:2-10.

Images