Method for synergistically smelting neodymium iron boron waste and electronic waste to efficiently recover valuable elements

Abstract

The application provides a method for efficiently recycling valuable elements by synergistically smelting neodymium iron boron waste and electronic waste, which comprises the following steps: preparing a mixture of powdered neodymium iron boron waste, fine-grained electronic waste, a slagging agent and a solid reducing agent; and using a top-blown smelting furnace to oxidize and reduce the mixture; by controlling the conditions of the oxidation process, the iron and rare earth in the mixture are oxidized into oxides and enter the slag, copper is not oxidized and captures rare and precious metals such as gold and silver to form crude copper and sink to the bottom of the furnace and is discharged; by controlling the conditions of the reduction process, the iron oxide in the mixed rare earth slag is reduced to metallic iron, and the rare earth oxide is not reduced and remains in the slag layer; the iron with a larger density than the rare earth slag sinks to the bottom of the furnace, and after static stratification, the iron and the rare earth slag are discharged from the metal outlet and the slag outlet respectively, so that the separation of the rare earth and the iron is realized; and finally, the synchronous recovery of the rare earth, the iron in the neodymium iron boron waste and the copper, gold and silver in the electronic waste is realized; the method has a short process flow, low energy consumption and good economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of neodymium iron boron waste recycling technology, and in particular to a method for efficiently recovering valuable elements by co-melting neodymium iron boron waste and electronic waste. Background Technology

[0002] Rare earth elements are important resources, often referred to as "industrial MSG." Neodymium iron boron (NdFeB) materials, in particular, are widely used in industries such as motors, defense, aerospace, and wind power due to their excellent performance. However, due to process limitations and equipment lifespan, a large amount of NdFeB waste is generated. This waste contains significant amounts of rare earth elements and iron, representing a substantial potential for utilization.

[0003] With the rapid development of technology and the accelerated pace of electronic product updates, the amount of waste electronic products is increasing day by day. The core component in electronic waste is the circuit board. Waste circuit boards not only contain valuable metals such as copper, gold, and silver, but also harmful heavy metal elements. They are listed in the National Hazardous Waste List (No. 900-045-49). If they are not utilized, it will not only waste valuable metals, but also pollute the environment.

[0004] Currently, most methods for treating NdFeB waste involve pyrometallurgical and hydrometallurgical processes to separate rare earth elements and iron. However, these methods do not fully utilize the separated iron, have high energy consumption per furnace, and generate large amounts of wastewater. Meanwhile, most electronic waste processing uses pyrometallurgical processes, including closed blast furnace smelting, Osmette furnace smelting, flash furnace smelting, Kaldor furnace smelting, side-blown furnace smelting, and bottom-blown furnace smelting. However, due to the inherent characteristics of these smelting processes, the comprehensive recovery of valuable metals from electronic waste still suffers from drawbacks such as low recovery rates, long processes, high energy consumption, low raw material adaptability, and severe secondary pollution.

[0005] In view of this, it is necessary to design an improved method for recovering rare earth elements and valuable metals from NdFeB waste and electronic waste to solve the aforementioned problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for the efficient recovery of valuable elements through the co-melting of neodymium iron boron waste and electronic waste.

[0007] To achieve the above-mentioned objectives, this invention provides a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste, comprising the following steps:

[0008] S1. Pre-treatment of NdFeB waste and electronic waste, including dismantling, sorting, crushing, and ball milling. The pre-treated powdered NdFeB waste and fine granular electronic waste are mixed with slagging agent and solid reducing agent, and the mixture is fed into the top-blown smelting furnace through the top feeding port using a feeding system.

[0009] S2. Natural gas and oxygen-enriched process air are introduced through the smelting torch. The oxygen mass percentage in the oxygen-enriched process air is 21% to 50%. The temperature inside the smelting furnace is controlled at 1300℃ to 1600℃. During this process, a weak oxidizing atmosphere is controlled. The mixed materials are in a highly dispersed floating state and fall from the top of the furnace to the bottom. The fine particulate materials are in full contact with the weak oxidizing atmosphere, creating good oxidation reaction kinetic conditions. This allows the iron and rare earth elements in the mixed materials to be rapidly oxidized into oxides and enter the slag. The copper is not oxidized and captures rare and precious metals such as gold and silver from electronic waste to form crude copper.

[0010] S3. The crude copper produced by weak oxidation smelting has a higher density than the slag and sinks to the bottom of the furnace. After standing and stratifying, the crude copper layer reaches a certain thickness and is discharged from the metal outlet.

[0011] S4. Add solid reducing agent again to the smelting furnace and introduce reducing gas and process air to make the residual oxygen concentration in the flue gas 1% to 3%, control the strong reducing atmosphere in the smelting furnace, and control the temperature in the smelting furnace 1300℃ to 1600℃ to carry out strong reduction smelting of the rare earth slag after weak oxidation smelting. Under the strong stirring of the gas flow at the outlet of the smelting lance, the rare earth slag and the solid reducing agent in the molten pool are fully mixed and contacted. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated inside the reduced slag, which further enhances the kinetic conditions of the reduction reaction, reducing the iron oxide in the rare earth slag to metallic iron. Since the density of iron is greater than that of rare earth slag, it sinks to the bottom of the furnace.

[0012] S5. After the reduction process is completed, stop adding reducing agent, remove the smelting torch from the molten pool for heat preservation, and allow the slag to settle and separate naturally. Iron and rare earth slag are discharged from the metal outlet and slag outlet respectively.

[0013] Furthermore, the electronic waste refers to discarded electronic or electrical equipment and its components, including products that are discarded due to technological obsolescence, damage, or reaching the end of their service life, such as televisions, refrigerators, computers, and mobile phones.

[0014] Furthermore, the particle size of the neodymium iron boron waste is below 50 mesh, and the particle size of the electronic waste is 10mm to 50mm.

[0015] Furthermore, the slag-forming agent is at least one of SiO2 and CaO, and its particle size is 1 mm to 10 mm.

[0016] Furthermore, the mass fraction of iron w(Fe) in the mixture is 15%–30%, the mass fraction of silicon dioxide w(SiO2) is 25%–40%, and the mass fraction of calcium oxide w(CaO) is 15%–25%.

[0017] Furthermore, the NdFeB waste has a high iron content, and when it is co-smelted with electronic waste, it can supplement the electronic waste with iron elements to form slag, without the need to add additional iron slag-forming agents.

[0018] Furthermore, the feeding system is used to add the mixture into the top-blown melting furnace at a rate of 2t / h to 4t / h through the top feed port.

[0019] Furthermore, the weak oxidizing atmosphere is achieved by a ratio of natural gas to oxygen-enriched process air volume of 1:24 to 1:30.

[0020] Furthermore, the reducing gas and solid reducing agent are both fuels and reducing agents.

[0021] Furthermore, the reducing gas is one or more of carbon monoxide, hydrogen, natural gas, and shale gas, preferably natural gas.

[0022] Furthermore, the reducing atmosphere is characterized by a ratio of reducing gas to process air volume of 1:10 to 1:12.

[0023] Furthermore, the solid reducing agent is at least one of coke and coal.

[0024] Furthermore, the bubbles are generated during a strong reduction reaction when the reducing gas cannot escape in time from the molten slag with high viscosity.

[0025] Furthermore, the slag settling and stratification process allows iron metal particles to settle rapidly within the bubble layer of the slag, significantly shortening the settling time.

[0026] Furthermore, the organic matter inherent in the electronic waste itself has a high calorific value, which can provide heat for the co-melting of NdFeB waste during combustion, greatly reducing energy consumption.

[0027] Furthermore, the reduced smelting flue gas passes through a secondary combustion system, a waste heat recovery system, a rapid cooling system, an activated carbon injection system, a dust removal system, and a desulfurization system before being discharged in compliance with emission standards.

[0028] Furthermore, the oxidation endpoint is determined by sampling and analysis using a probe. The endpoint is also determined by observing and analyzing the morphology of the reduction residue using a probe.

[0029] The present invention provides a method for efficient recovery of valuable elements through co-smelting of NdFeB waste and electronic waste, which has the following features and advantages:

[0030] (1) This method involves mixing powdered NdFeB waste and fine-particle electronic waste with slagging agents and solid reducing agents. The mixture is fed into the furnace through the top charging port. During its descent, the fine-particle mixed waste is highly dispersed and comes into full contact with the high-temperature oxidizing atmosphere of the furnace, creating favorable kinetic conditions for oxidation reaction and rapidly undergoing a weak oxidation reaction. This causes iron and rare earth elements to be oxidized and enter the slag, while the copper in the electronic waste remains unoxidized. It forms crude copper molten metal with gold, silver, and other rare and precious metals in the electronic waste, falls into the bottom molten pool, and is discharged, separating from the rare earth slag. Furthermore, the NdFeB waste has a high iron content, which can supplement the electronic waste with iron elements for slagging when co-smelted with it, eliminating the need for additional iron-based slagging agents. In addition, the organic matter inherent in the electronic waste has a high calorific value, which can provide some heat for the co-smelting of NdFeB waste during combustion, greatly reducing energy consumption.

[0031] (2) Rare earth slag is stirred by the gas flow at the outlet of the smelting lance and fully mixed with the solid reducing agent in the molten pool, creating good kinetic conditions for reduction reaction. Iron oxides in rare earth slag can be quickly reduced to metallic iron, while rare earth oxides are not reduced and continue to remain in the slag layer.

[0032] (3) Iron has a higher density than rare earth slag, and can quickly sink into the metal layer in the molten slag foam layer. After static stratification, the molten iron metal and rare earth slag are discharged from the metal port and slag port respectively, without the need for forced separation by measures such as super gravity slag-metal fusion separation and magnetic separation.

[0033] In summary, this invention enables the simultaneous recovery of rare earth elements from NdFeB waste and copper, gold, and silver from electronic waste, truly achieving multi-recovery from a single furnace. It features a short process, low energy consumption, and significant economic and environmental benefits, making it highly valuable for widespread application. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating a method for the efficient recovery of valuable elements through the co-melting of neodymium iron boron waste and electronic waste, as proposed in this invention.

[0036] Figure 2 This is a schematic diagram of the top-blown smelting furnace used in the embodiment when recycling rare earth elements, copper, gold, and silver from neodymium iron boron waste and electronic waste using the recycling method proposed in this invention.

[0037] The labels in the attached diagram are: 1. Top-blown smelting furnace; 2. Smelting lance; 3. Probe rod; 4. Feed port; 5. Slag discharge port; 6. Metal port. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0040] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0041] This invention provides a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste, such as... Figure 1 As shown, it includes the following steps:

[0042] S1. Pre-treatment of NdFeB waste and electronic waste, including dismantling, sorting, crushing, and ball milling. The pre-treated powdered NdFeB waste and fine granular electronic waste are mixed with slagging agent and solid reducing agent, and the mixture is fed into the top-blown smelting furnace through the top feeding port using a feeding system.

[0043] S2. Natural gas and oxygen-enriched process air are introduced through the smelting torch. The oxygen mass percentage in the oxygen-enriched process air is 21% to 50%. The temperature inside the smelting furnace is controlled at 1300℃ to 1600℃. During this process, a weak oxidizing atmosphere is controlled. The mixed materials are in a highly dispersed floating state and fall from the top of the furnace to the bottom. The fine particulate materials are in full contact with the weak oxidizing atmosphere, creating good oxidation reaction kinetic conditions. This allows the iron and rare earth elements in the mixed materials to be rapidly oxidized into oxides and enter the slag. The copper is not oxidized and captures rare and precious metals such as gold and silver from electronic waste to form crude copper.

[0044] S3. The crude copper produced by weak oxidation smelting has a higher density than the slag and sinks to the bottom of the furnace. After standing and stratifying, the crude copper layer reaches a certain thickness and is discharged from the metal outlet.

[0045] S4. Add solid reducing agent again to the smelting furnace and introduce reducing gas and process air to make the residual oxygen concentration in the flue gas 1% to 3%, control the strong reducing atmosphere in the smelting furnace, and control the temperature in the smelting furnace 1300℃ to 1600℃ to carry out strong reduction smelting of the rare earth slag after weak oxidation smelting. Under the strong stirring of the gas flow at the outlet of the smelting lance, the rare earth slag and the solid reducing agent in the molten pool are fully mixed and contacted. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated inside the reduced slag, which further enhances the kinetic conditions of the reduction reaction, reducing the iron oxide in the rare earth slag to metallic iron. Since the density of iron is greater than that of rare earth slag, it sinks to the bottom of the furnace.

[0046] S5. After the reduction process is completed, stop adding reducing agent, remove the smelting torch from the molten pool for heat preservation, and allow the slag to settle and separate naturally. Iron and rare earth slag are discharged from the metal outlet and slag outlet respectively.

[0047] The above-mentioned recycling process is completed using a top-blown smelting furnace 1, the structural diagram of which is shown below. Figure 2 As shown, the top-blown smelting furnace 1 includes a furnace body. The top of the furnace body has a flue outlet and a charging port 4, while the bottom of the furnace body has a slag discharge port 5 and a metal outlet 6. Inside the furnace body, there is a smelting lance 2 that penetrates the inner wall of the furnace body and extends to the lower part of the furnace body, and a probe 3. The smelting lance 2 is used to introduce reducing gas and process air into the furnace. The probe 3 is used to measure the liquid level in the furnace, and the composition and morphology of the reducing slag at the upper part of the probe 3 are analyzed to determine the reduction endpoint and reduction time. In other embodiments, other smelting furnaces that can achieve the above objectives can also be selected as needed.

[0048] In one embodiment of the present invention, in step S1, the electronic waste refers to discarded electronic or electrical equipment and its components, including products that are discarded due to technological obsolescence, damage, or reaching the end of their service life, such as televisions, refrigerators, computers, and mobile phones.

[0049] In one embodiment of the present invention, in step S1, the materials entering the furnace need to be pre-treated so that the particle size of the NdFeB waste is below 50 mesh and the particle size of the electronic waste is 10mm to 50mm.

[0050] In one embodiment of the present invention, in step S1, the slag-forming agent is at least one of SiO2 and CaO, and its particle size is 1 mm to 10 mm.

[0051] In one embodiment of the present invention, in step S1, the mass fraction of iron w(Fe) in the mixture is 15% to 30%, the mass fraction of silicon dioxide w(SiO2) is 25% to 40%, and the mass fraction of calcium oxide w(CaO) is 15% to 25%.

[0052] In one embodiment of the present invention, in step S1, the NdFeB waste has a high iron content, and when it is smelted in conjunction with electronic waste, it can supplement the electronic waste with iron elements to form slag, without the need to add additional iron slag-forming agents.

[0053] In one embodiment of the present invention, in step S1, the organic matter contained in the electronic waste itself has a high calorific value, which can provide some heat for the co-melting of NdFeB waste during combustion, thus greatly reducing energy consumption.

[0054] In one embodiment of the present invention, in step S1, the feed system is used to add the mixture into the top blown smelting furnace from the top feed port at a rate of 2t / h to 4t / h.

[0055] In one embodiment of the present invention, in step S2, the weak oxidizing atmosphere is a ratio of natural gas to oxygen-enriched process air volume of 1:24 to 1:30.

[0056] In one embodiment of the present invention, in step S4, the reducing gas and the solid reducing agent are both fuel and reducing agent.

[0057] In one embodiment of the present invention, in step S4, the reducing gas is one or more of carbon monoxide, hydrogen, natural gas, and shale gas, preferably natural gas.

[0058] In one embodiment of the present invention, in step S4, the solid reducing agent is at least one of coke and coal.

[0059] In one embodiment of the present invention, in step S4, the amount of solid reducing agent added is 0.7t / h to 1.2t / h.

[0060] In one embodiment of the present invention, in step S4, the reducing atmosphere is a ratio of reducing gas to process air volume of 1:10 to 1:12, and the residual oxygen concentration in the flue gas is 1% to 3%.

[0061] In one embodiment of the present invention, in step S4, the reduced smelting flue gas passes through a flue gas secondary combustion system, a waste heat recovery system, a flue gas quenching system, an activated carbon injection system, a dust removal system, and a desulfurization system before being discharged in compliance with emission standards.

[0062] In one embodiment of the present invention, in step S4, the bubbles are generated because the reducing gas cannot escape in time from the molten slag with high viscosity during the strong reduction reaction process.

[0063] In one embodiment of the present invention, in step S3, the slag is allowed to settle into layers, and the alloy particles can quickly settle on the surface of the bubble layer of the slag, which greatly shortens the settling time.

[0064] In one embodiment of the present invention, in step S2, the oxidation endpoint is determined by sampling, observation and analysis using the probe 3.

[0065] In one embodiment of the present invention, in step S4, the morphology of the reduction residue is determined by sampling, observation and analysis using the probe 3 to determine the endpoint.

[0066] In the above technical solution, the characteristics of NdFeB waste (high iron content, low calorific value) and electronic waste (low iron content, high calorific value) are utilized. By mixing powdered NdFeB waste, finely granulated electronic waste, quartz, limestone (the main component of limestone is calcium carbonate (CaCO3), which decomposes into CaO at high temperatures in the furnace), and a solid reducing agent, the NdFeB waste can supplement the electronic waste with iron for slag formation without the need for additional iron-based slag-forming agents. Meanwhile, the high calorific value of the electronic waste provides heat for the co-smelting of the NdFeB waste, significantly reducing energy consumption. When the mixture is added to the top-blown smelting furnace, the powdered material falls and comes into full contact with the oxidizing atmosphere in the furnace, creating favorable oxidation reaction kinetics. This allows the iron and rare earth elements in the NdFeB waste to be rapidly oxidized and incorporated into the slag. Copper in electronic waste is not oxidized and traps valuable metals such as gold and silver to form a crude copper alloy melt. This crude copper alloy melt has a higher density than rare earth slag, causing it to sink rapidly to the bottom of the furnace and be periodically discharged. The rare earth slag melt, after removing the crude copper, is rapidly drawn into the molten pool by the gas flow from the smelting lance outlet. It mixes thoroughly with the solid reducing agent inside the pool, undergoing a reduction reaction to reduce to metallic iron, while the rare earth oxides remain unreduced in the slag layer. This process fully utilizes the high iron content of NdFeB waste and the high calorific value of electronic waste to recover copper, avoiding the drawback of needing to supplement iron during smelting due to the low iron content of electronic waste. By controlling the reduction conditions and utilizing the higher viscosity of the high-silicon, high-calcium slag, a foam layer is easily generated in the molten slag during strong reduction smelting, increasing the specific surface area of ​​the slag and enhancing the gas-solid two-phase kinetics, allowing the iron oxides to be rapidly reduced and separated from the rare earth slag. After the reduction reaction is complete, stop adding reducing agent, remove the smelting lance from the molten pool for heat preservation, and allow the slag to settle and separate naturally. Iron and rare earth slag are discharged from the metal outlet and slag outlet, respectively.

[0067] The following specific embodiments further illustrate the method for efficient recovery of valuable elements through co-smelting of NdFeB waste and electronic waste proposed in this invention:

[0068] Example 1

[0069] This embodiment proposes a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste. The specific reduction and recovery method is as follows:

[0070] Neodymium iron boron waste with a particle size of 50 mesh and electronic waste with a block size of 50 mm were mixed with quartz, limestone, and coke. The mass fraction of iron (w(Fe)) in the mixture was 22%, the mass fraction of silicon dioxide (w(SiO2)) was 33%, and the mass fraction of calcium oxide (w(CaO)) was 18%. The mixture was added to the top-blown smelting furnace 1 through the feeding port 4. The furnace temperature was 1362℃, and the mass percentage of oxygen in the oxygen-enriched process air was 21%. With a residual oxygen concentration of 3%, oxidative smelting was carried out for 40 minutes to obtain crude copper with a copper content of 93.2% and a copper recovery rate of 92.5%. The ratio of reducing natural gas to process air was controlled at 1:12, and smelting was carried out for 20 minutes. After settling for 5 minutes, iron-rich phase with an iron content of 93.5% and rare earth slag with a neodymium content of 46.3% were obtained from metal outlet 6 and slag outlet 5, respectively. The iron recovery rate in the NdFeB waste was 93.6%, and the rare earth recovery rate was 93.3%.

[0071] Example 2

[0072] This embodiment proposes a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste. The specific reduction and recovery method is as follows:

[0073] Neodymium iron boron waste with a particle size of 50 mesh and electronic waste with a block size of 40 mm were mixed with quartz, limestone, and coke. The mass fraction of iron (w(Fe)) in the mixture was 21%, the mass fraction of silicon dioxide (w(SiO2)) was 33%, and the mass fraction of calcium oxide (w(CaO)) was 19%. The mixture was added to the top-blown smelting furnace 1 through the feeding port 4. The furnace temperature was 1422℃, and the mass percentage of oxygen in the oxygen-enriched process air was 25%. With a residual oxygen concentration of 3%, oxidative smelting was carried out for 40 minutes to obtain crude copper with a copper content of 92.5% and a copper recovery rate of 92.1%. The ratio of reducing natural gas to process air was controlled at 1:12, and smelting was carried out for 20 minutes. After settling for 10 minutes, iron-rich phase with an iron content of 91.9% and rare earth slag with a neodymium content of 46.7% were obtained from metal outlet 6 and slag outlet 5, respectively. The iron recovery rate in the NdFeB waste was 90.2%, and the rare earth recovery rate was 93.5%.

[0074] Example 3

[0075] This embodiment proposes a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste. The specific reduction and recovery method is as follows:

[0076] Neodymium iron boron waste with a particle size of 100 mesh and electronic waste with a block size of 30 mm were mixed with quartz, limestone, and coke. The mass fraction of iron (w(Fe)) in the mixture was 23%, the mass fraction of silicon dioxide (w(SiO2)) was 33%, and the mass fraction of calcium oxide (w(CaO)) was 19%. The mixture was added to the top-blown smelting furnace 1 through the feeding port 4. The furnace temperature was 1455℃, and the mass percentage of oxygen in the oxygen-enriched process air was 30%. With a residual oxygen concentration of 2%, oxidative smelting was carried out for 40 minutes to obtain crude copper with a copper content of 92.3% and a copper recovery rate of 92.6%. The ratio of reducing natural gas to process air was controlled at 1:11, and the reduction smelting was carried out for 25 minutes. After settling for 15 minutes, iron-rich phase with an iron content of 91.7% and rare earth slag with a neodymium content of 46.8% were obtained from metal outlet 6 and slag outlet 5, respectively. The iron recovery rate in the NdFeB waste was 90.5%, and the rare earth recovery rate was 94.5%.

[0077] Example 4

[0078] This embodiment proposes a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste. The specific reduction and recovery method is as follows:

[0079] Neodymium iron boron waste with a particle size of 100 mesh and electronic waste with a block size of 20 mm were mixed with quartz, limestone, and coke. The mass fraction of iron (w(Fe)) in the mixture was 27%, the mass fraction of silicon dioxide (w(SiO2)) was 32%, and the mass fraction of calcium oxide (w(CaO)) was 19%. The mixture was added to the top-blown smelting furnace 1 through the feeding port 4. The furnace temperature was 1465℃, and the mass percentage of oxygen in the oxygen-enriched process air was 35%. With a residual oxygen concentration of 2%, oxidative smelting was carried out for 40 minutes to obtain crude copper with a copper content of 92.4% and a copper recovery rate of 93.3%. The ratio of reducing natural gas to process air was controlled at 1:11, and smelting was carried out for 25 minutes. After settling for 18 minutes, iron-rich phase with an iron content of 92.5% and rare earth slag with a neodymium content of 46.5% were obtained from metal outlet 6 and slag outlet 5, respectively. The iron recovery rate in the NdFeB waste was 91.6%, and the rare earth recovery rate was 94.2%.

[0080] Example 5

[0081] This embodiment proposes a method for the efficient recovery of valuable elements through the co-smelting of NdFeB waste and electronic waste. The specific reduction and recovery method is as follows:

[0082] Neodymium iron boron waste with a particle size of 100 mesh and electronic waste with a block size of 10 mm were mixed with quartz, limestone, and coke. The mass fraction of iron (w(Fe)) in the mixture was 26%, the mass fraction of silicon dioxide (w(SiO2)) was 32%, and the mass fraction of calcium oxide (w(CaO)) was 18%. The mixture was added to the top-blown smelting furnace 1 through the feeding port 4. The furnace temperature was 1485℃, and the mass percentage of oxygen in the oxygen-enriched process air was 40%. With a residual oxygen concentration of 2%, oxidative smelting was carried out for 40 minutes to obtain crude copper with a copper content of 91.4% and a copper recovery rate of 92.0%. The ratio of reducing natural gas to process air was controlled at 1:10, and smelting was carried out for 25 minutes. After settling for 25 minutes, iron-rich phase with an iron content of 94.3% and rare earth slag with a neodymium content of 47.2% were obtained from metal outlet 6 and slag outlet 5, respectively. The iron recovery rate in the NdFeB waste was 92.3%, and the rare earth recovery rate was 95.7%.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for efficiently recovering valuable elements through co-smelting of NdFeB waste and electronic waste, characterized in that, Includes the following steps: S1. Dismantle, sort, crush, and ball mill pre-treat neodymium iron boron waste and electronic waste. Mix the pre-treated powdered neodymium iron boron waste and fine granular electronic waste with slagging agent and solid reducing agent. Use the feeding system to add the mixture to the top blown smelting furnace from the top feeding port. S2. Natural gas and oxygen-enriched process air are introduced through the smelting torch. The oxygen mass percentage in the oxygen-enriched process air is 21% to 50%. The temperature inside the smelting furnace is controlled at 1300℃ to 1600℃. During this process, a weak oxidizing atmosphere is controlled. The mixed materials are in a highly dispersed floating state and fall from the top of the furnace to the bottom. The fine particulate materials are in full contact with the weak oxidizing atmosphere, creating good oxidation reaction kinetic conditions. This allows the iron and rare earth elements in the mixed materials to be rapidly oxidized into oxides and enter the slag. The copper is not oxidized and captures rare and precious metals such as gold and silver in electronic waste to form crude copper. S3. The crude copper produced by weak oxidation smelting has a higher density than the slag and sinks to the bottom of the furnace. After standing and stratifying, the crude copper layer is discharged from the metal outlet. S4. Add solid reducing agent to the smelting furnace again and introduce reducing gas and process air to make the residual oxygen concentration of flue gas 1% to 3%, control the strong reducing atmosphere in the smelting furnace, and control the temperature in the smelting furnace to 1300℃ to 1600℃. Perform strong reduction smelting on the rare earth slag after weak oxidation smelting. Under the strong stirring of the airflow at the outlet of the smelting lance, the rare earth slag and the solid reducing agent in the molten pool are fully mixed and contacted. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated inside the reduced slag, which further strengthens the kinetic conditions of the reduction reaction. The iron oxide in the rare earth slag is reduced to metallic iron. Iron has a higher density than rare earth slag and sinks to the bottom of the furnace. S5. After the reduction process is completed, stop adding reducing agent, remove the smelting torch from the molten pool for heat preservation, and allow the slag to settle and separate naturally. The iron and rare earth slag are discharged from the metal outlet and slag outlet respectively. The neodymium iron boron waste has a particle size of less than 50 mesh, and the electronic waste has a block size of 10mm to 50mm; The mass fraction of iron (w(Fe)) in the mixture is 15%–30%, the mass fraction of silicon dioxide (w(SiO2)) is 25%–40%, and the mass fraction of calcium oxide (w(CaO)) is 15%–25%. The ratio of natural gas to oxygen-enriched process air volume in the weakly oxidizing atmosphere is 1:24 to 1:30; the ratio of reducing gas to process air volume in the reducing atmosphere is 1:10 to 1:

12.

2. The method according to claim 1, characterized in that, The electronic waste refers to discarded electronic or electrical equipment and its components.

3. The method according to claim 1, characterized in that, The slag-forming agent is at least one of SiO2 and CaO, and its particle size is 1mm to 10mm.

4. The method according to claim 3, characterized in that, The feeding system is used to add the mixture into the top-blown smelting furnace from the top charging port at a rate of 2t / h to 4t / h.

5. The method according to claim 1, characterized in that, The reducing gas and solid reducing agent can be used as fuel.

6. The method according to claim 5, characterized in that, The reducing gas is one or more of carbon monoxide, hydrogen, natural gas, and shale gas; the solid reducing agent is at least one of coke and coal.

7. The method according to claim 1, characterized in that, After reduction, the smelting flue gas passes through a secondary combustion system, a waste heat recovery system, a flue gas quenching system, an activated carbon injection system, a dust removal system, and a desulfurization system before being discharged in compliance with standards.

8. The method according to claim 1, characterized in that, The bubbles mentioned above are generated during a strong reduction reaction when the reducing gas cannot escape in time from the molten slag with high viscosity. The organic matter contained in the electronic waste has a high calorific value, and can provide heat for the co-melting of neodymium iron boron waste during combustion; The NdFeB waste has a high iron content, and when it is co-smelted with electronic waste, it can supplement the smelting of electronic waste with iron elements to form slag, without the need to add additional iron slag-forming agents. The slag is allowed to settle and stratify, allowing iron metal particles to settle rapidly at the edge of the bubble layer in the slag.

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