Method for efficiently recovering valuable elements through collaborative smelting of neodymium iron boron waste and electronic waste

Abstract

The invention provides a method for efficiently recovering valuable elements through collaborative smelting of neodymium-iron-boron waste and electronic waste, which comprises the following steps: proportioning powdery neodymium-iron-boron waste, fine-particle electronic waste, a slag former and a solid reducing agent, and carrying out redox smelting on a mixture by using a top-blown smelting furnace; by controlling the conditions of the oxidation process, iron and rare earth in the mixed material are oxidized into oxides to enter slag, copper is not oxidized, and gold, silver and other rare and precious metals are captured to form crude copper which sinks to the bottom of the furnace and is discharged; by controlling the conditions of the reduction process, iron oxide in the mixed rare earth slag is reduced into metal iron, rare earth oxide is not reduced and reserved in a slag layer, iron sinks to the bottom of the furnace due to the fact that the density of the iron is larger than that of the rare earth slag, the iron is discharged from a metal opening and a slag opening after standing and layering, and separation of rare earth and iron is achieved. And finally, synchronous recovery of rare earth and iron in the neodymium iron boron waste and copper, gold and silver in the electronic waste can be achieved, and the method is short in process and low in energy consumption and has good economic and environment-friendly benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and utilizing NdFeB waste, and in particular to a method for efficiently recovering valuable elements by co-smelting NdFeB waste and electronic waste. Background Art

[0002] Rare earth elements are a vital resource, often called the "MSG of industry." Neodymium iron boron (NdFeB) materials, due to their excellent performance, are widely used in industries such as motors, defense, aviation, and wind power. However, due to process and equipment lifespan issues, a large amount of NdFeB waste is generated. This NdFeB waste contains significant amounts of rare earth elements and iron, and thus holds great potential for utilization.

[0003] With the rapid development of science and technology, the updating and iteration of electronic products are accelerating, and the number of waste electronic products is increasing. The core components of electronic waste are circuit boards. Waste circuit boards contain not only valuable metals such as copper, gold, and silver, but also harmful heavy metal elements. They are included in the National Hazardous Waste List (No. 900-045-49). If they are not utilized, they will not only cause waste of valuable metals, but also pollute the environment.

[0004] Currently, most NdFeB waste treatment methods use pyrometallurgical and hydrometallurgical separation of rare earths and iron. However, this method does not fully utilize the separated iron, consumes high energy consumption per furnace, and produces a large amount of wastewater. Most electronic waste treatment processes use pyrometallurgical processes. Existing pyrometallurgical processes mainly include closed blast furnace smelting, Ausmelt furnace smelting, flash furnace smelting, Kaldo furnace smelting, side-blown furnace smelting, and bottom-blown furnace smelting. Due to the characteristics of these smelting processes, the comprehensive recovery of valuable metals from electronic waste still has disadvantages such as low recovery rate, long process, 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 and valuable metals from NdFeB waste and electronic waste to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to provide a method for efficiently recovering valuable elements by co-smelting NdFeB waste and electronic waste.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a method for efficiently recovering valuable elements by co-smelting NdFeB waste and electronic waste, comprising the following steps:

[0008] S1. Dismantle, sort, crush, and ball-mill the NdFeB scrap and electronic scrap for pretreatment. Mix the pretreated powdered NdFeB scrap and finely granulated electronic scrap with a slag-forming agent and a solid reducing agent, and use a feeding system to feed the mixture into the top-blown smelting furnace from the top charging port.

[0009] S2. Natural gas and oxygen-enriched process air are introduced through the smelting lance. The mass percentage of oxygen in the oxygen-enriched process air is 21% to 50%. The temperature in the smelting furnace is controlled to be 1300℃ to 1600℃. During this process, a weak oxidizing atmosphere is controlled, and the mixed material is in a highly dispersed floating state and falls from the top of the furnace to the bottom of the furnace. The fine granular material is fully in contact with the weak oxidizing atmosphere, creating good oxidation reaction kinetic conditions, so that the iron and rare earth in the mixed material are quickly oxidized into oxides and enter the slag, while the copper is not oxidized and captures rare and precious metals such as gold and silver in the 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 stratification, the crude copper layer reaches a certain thickness and is discharged from the metal port.

[0011] S4. Solid reducing agent is added to the smelting furnace again, and reducing gas and process air are introduced to maintain a residual oxygen concentration in the flue gas of 1% to 3%. The smelting furnace is controlled to a strongly reducing atmosphere and a temperature of 1300°C to 1600°C. Strong reduction smelting is then performed on the rare earth slag after weak oxidation smelting. Under the strong stirring of the airflow at the smelting lance outlet, the rare earth slag is thoroughly mixed and contacted with the solid reducing agent in the molten pool. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated within the reduced slag, further enhancing the reduction reaction kinetics. This reduces the iron oxides in the rare earth slag to metallic iron, which has a greater density than the rare earth slag and sinks to the bottom of the furnace.

[0012] S5. After the reduction process is completed, stop adding the reducing agent, lift the smelting lance out of the molten pool for insulation, and allow the slag to naturally settle and stratify. The iron and rare earth slag are discharged from the metal port and slag port respectively.

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

[0014] Furthermore, the particle size of the NdFeB scrap is below 50 mesh, and the block size of the electronic scrap is 10 mm to 50 mm.

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

[0016] Furthermore, 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%.

[0017] Furthermore, the NdFeB scrap has a high iron content, and when it is smelted together with electronic scrap, it can supplement the electronic scrap with iron elements for slag formation without adding any additional iron slag forming agent.

[0018] Furthermore, a feeding system is used to feed the mixed material into the top-blown smelting furnace from a feeding port on the top of the furnace at a rate of 2 t / h to 4 t / h.

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

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

[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 has 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 the strong reduction reaction when the reducing gas cannot escape in time in the slag with high viscosity.

[0025] Furthermore, the slag is statically layered so that the iron metal particles can quickly settle in the bubble layer of the slag, which greatly shortens the static settling time.

[0026] Furthermore, the organic matter contained in the electronic waste has a high calorific value, which can provide heat for the co-smelting of the NdFeB waste when burned, greatly reducing energy consumption.

[0027] Furthermore, the reduced smelting flue gas passes through a flue gas secondary combustion system, a waste heat recovery system, a flue gas 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, observing, and analyzing the morphology of the reduced slag using a probe rod.

[0029] The present invention provides a method for efficiently recovering valuable elements by collaboratively smelting NdFeB waste and electronic waste, which has the following characteristics and advantages:

[0030] (1) This method is to mix powdered NdFeB scrap and fine-grained electronic scrap with a slag-forming agent and a solid reducing agent. The mixture is fed into the furnace from the charging port. The fine-grained mixed scrap is highly dispersed during the falling process and is fully exposed to the high-temperature oxidizing atmosphere of the furnace, creating good oxidation reaction kinetic conditions and rapidly undergoing a weak oxidation reaction, so that iron and rare earth are oxidized into slag, while the copper in the electronic scrap is not oxidized. It forms a crude copper metal melt with rare precious metals such as gold and silver in the electronic scrap and falls into the furnace bottom molten pool and is discharged, and is separated from the rare earth slag. In addition, NdFeB scrap has a high iron content. When it is co-smelted with electronic scrap, it can supplement the iron element for slag formation without the need to add additional iron slag-forming agents. In addition, the organic matter in the electronic scrap itself has a high calorific value. When burned, it can provide part of the heat for the co-smelting of NdFeB scrap, greatly reducing energy consumption.

[0031] (2) The rare earth slag is fully mixed and contacted with the solid reducing agent in the molten pool under the stirring of the air flow at the outlet of the smelting lance, creating good reduction reaction kinetic conditions. The iron oxides in the rare earth slag can be quickly reduced to metallic iron, while the 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 slag foam layer. After static stratification, the iron metal melt and rare earth slag are discharged from the metal port and slag port respectively, without the need for forced separation by ultra-gravity slag-metal melting and magnetic separation.

[0033] In summary, the present invention can realize the synchronous recovery of rare earth in NdFeB waste and copper, gold and silver in electronic waste, truly realizing multiple recovery in one furnace, short process, low energy consumption, good economic and environmental benefits, and good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the drawings required for describing the specific implementation or the prior art will be briefly introduced below. Obviously, the drawings described below are only one implementation of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a flow chart of a method for efficiently recovering valuable elements by collaboratively smelting NdFeB waste and electronic waste, as proposed by the present invention;

[0036] Figure 2 This is a schematic structural diagram of a top-blown smelting furnace used in the embodiment to recover rare earths, copper, gold and silver from NdFeB waste and electronic waste using the recovery method proposed by the present invention.

[0037] The markings in the accompanying drawings are: 1. top-blown smelting furnace; 2. smelting lance; 3. detection rod; 4. feeding port; 5. slag discharge port; 6. metal port. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

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

[0040] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0041] The present invention provides a method for efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste, such as Figure 1 As shown, the following steps are included:

[0042] S1. Dismantle, sort, crush, and ball-mill the NdFeB scrap and electronic scrap for pretreatment. Mix the pretreated powdered NdFeB scrap and finely granulated electronic scrap with a slag-forming agent and a solid reducing agent, and use a feeding system to feed the mixture into the top-blown smelting furnace from the top charging port.

[0043] S2. Natural gas and oxygen-enriched process air are introduced through the smelting lance. The mass percentage of oxygen in the oxygen-enriched process air is 21% to 50%. The temperature in the smelting furnace is controlled to be 1300℃ to 1600℃. During this process, a weak oxidizing atmosphere is controlled, and the mixed material is in a highly dispersed floating state and falls from the top of the furnace to the bottom of the furnace. The fine granular material is fully in contact with the weak oxidizing atmosphere, creating good oxidation reaction kinetic conditions, so that the iron and rare earth in the mixed material are quickly oxidized into oxides and enter the slag, while the copper is not oxidized and captures rare and precious metals such as gold and silver in the 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 stratification, the crude copper layer reaches a certain thickness and is discharged from the metal port.

[0045] S4. Solid reducing agent is added to the smelting furnace again, and reducing gas and process air are introduced to maintain a residual oxygen concentration in the flue gas of 1% to 3%. The smelting furnace is controlled to a strongly reducing atmosphere and a temperature of 1300°C to 1600°C. Strong reduction smelting is then performed on the rare earth slag after weak oxidation smelting. Under the strong stirring of the airflow at the smelting lance outlet, the rare earth slag is thoroughly mixed and contacted with the solid reducing agent in the molten pool. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated within the reduced slag, further enhancing the reduction reaction kinetics. This reduces the iron oxides in the rare earth slag to metallic iron, which has a greater density than the rare earth slag and sinks to the bottom of the furnace.

[0046] S5. After the reduction process is completed, stop adding the reducing agent, lift the smelting lance out of the molten pool for insulation, and allow the slag to naturally settle and stratify. The iron and rare earth slag are discharged from the metal port and slag port respectively.

[0047] The above recovery process is completed with the help of a top-blown smelting furnace 1, the structural diagram of which is shown in FIG. Figure 2 As shown, a top-blown smelting furnace 1 comprises a furnace body, with a flue outlet and a charging port 4 provided at the top, a slag discharge port 5 and a metal port 6 provided at the bottom, and a smelting lance 2 and a probe 3 provided within the furnace body, extending through the inner wall and to the bottom. The smelting lance 2 is used to introduce reducing gas and process air into the furnace, and the probe 3 is used to measure the liquid level within the furnace and analyze the composition and morphology of the reduced slag above the probe 3 to determine the reduction endpoint and reduction time. In other embodiments, other smelting furnaces that can achieve the above-mentioned objectives may be selected as needed.

[0048] As an embodiment of the present invention, in step S1, the electronic waste is discarded electronic or electrical equipment and its parts, including products discarded due to technological obsolescence, damage or reaching the end of their service life, such as televisions, refrigerators, computers, mobile phones, etc.

[0049] As an 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 scrap is below 50 mesh and the block size of the electronic scrap is 10 mm to 50 mm.

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

[0051] As an 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] As an embodiment of the present invention, in step S1, the NdFeB scrap has a high iron content, and when it is co-smelted with electronic scrap, iron elements can be added to the electronic scrap for slag formation without the need to add additional iron slag forming agents.

[0053] As an embodiment of the present invention, in step S1, the organic matter contained in the electronic waste has a high calorific value, which can provide part of the heat for the co-smelting of the NdFeB waste during combustion, thereby greatly reducing energy consumption.

[0054] As an embodiment of the present invention, in step S1, the mixed material is fed into the top-blown smelting furnace from the feeding port at the top of the furnace using a feeding system at a rate of 2 t / h to 4 t / h.

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

[0056] As an embodiment of the present invention, in step S4, the reducing gas and the solid reducing agent serve as both the fuel and the reducing agent.

[0057] As an 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] As an embodiment of the present invention, in step S4, the solid reducing agent is at least one of coke and coal.

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

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

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

[0062] As an embodiment of the present invention, in step S4, bubbles are generated during a strong reduction reaction when reducing gas cannot escape in time from the slag with high viscosity.

[0063] As an embodiment of the present invention, in step S3, the slag is allowed to stand and stratify into alloy particles which can quickly settle on the surface of the bubble layer of the slag, thereby greatly shortening the standing and settling time.

[0064] As an embodiment of the present invention, in step S2, sampling, observation, analysis and determination of the oxidation end point are performed by using the probe 3.

[0065] As an embodiment of the present invention, in step S4, the end point is determined by sampling, observing, analyzing and judging the morphology of the reduced slag through the detection rod 3.

[0066] The above technical solution takes advantage of the fact that NdFeB scrap has a high iron content and low calorific value, while electronic scrap has a low iron content but high calorific value. By mixing powdered NdFeB scrap and fine-granular electronic scrap with quartz stone, limestone (the main component of limestone is calcium carbonate CaCO3, which decomposes into CaO under high temperature in the furnace), and a solid reducing agent, the NdFeB scrap can supplement the iron element of the electronic scrap for slag formation, eliminating the need for additional iron slag-forming agents. The high calorific value of the electronic scrap can provide heat for the co-smelting of the NdFeB scrap when burned, greatly reducing energy consumption. When the mixture is added to the top-blown smelting furnace, the powdered material fully contacts the oxidizing atmosphere in the furnace during its fall, creating favorable oxidation reaction kinetic conditions, allowing the iron and rare earth elements in the NdFeB scrap to be rapidly oxidized and incorporated into the slag. The copper in the electronic scrap remains unoxidized and captures valuable metals such as gold and silver, forming a blister copper alloy melt. This molten copper alloy is denser than the rare earth slag and rapidly sinks to the furnace bottom for regular discharge. The rare earth slag melt, free of blister copper, is rapidly drawn into the molten pool by the airflow at the smelting lance outlet, where it mixes thoroughly with the solid reducing agent within the molten pool, undergoing a reduction reaction to form metallic iron. The rare earth oxides remain unreduced and remain in the slag layer. This process leverages the high iron content of NdFeB scrap and the high calorific value of electronic scrap to recover copper from electronic scrap, avoiding the need for additional iron supplementation during the smelting process due to the low iron content of electronic scrap. By controlling the reduction conditions and utilizing the higher viscosity of the high-silicon, high-calcium slag, a foam layer is easily formed in the molten slag during strong reduction smelting, increasing the slag surface area and strengthening the gas-solid two-phase dynamics, enabling rapid reduction of the iron oxides and their separation from the rare earth slag. After the reduction reaction is completed, stop adding the reducing agent, lift the smelting lance out of the molten pool for insulation, and allow the slag to naturally settle and stratify. The iron and rare earth slag are discharged from the metal port and slag port respectively.

[0067] The following is a further description of the method for efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste proposed by the present invention in conjunction with specific embodiments:

[0068] Example 1

[0069] This embodiment proposes a method for efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste. The specific reduction recovery method is as follows:

[0070] NdFeB scrap with a particle size of 50 mesh and electronic scrap with a block size of 50 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron in the mixed material is 22%, the mass fraction of silicon dioxide is 33%, and the mass fraction of calcium oxide is 18%. The mixed material is added into the top-blown smelting furnace 1 through the feeding port 4. The temperature in the furnace is 1362 ° C, the mass percentage of oxygen in the oxygen-enriched process air is 21%, and the flue gas is 20% by weight. The residual oxygen concentration is 3%, and the oxidation smelting is carried out for 40 minutes to obtain crude copper with a copper content of 93.2%, and the copper recovery rate is 92.5%; the ratio of reducing natural gas to process air is controlled to be 1:12, and the reduction smelting is carried out for 20 minutes. After static sedimentation for 5 minutes, an iron-rich phase with an iron content of 93.5% and a rare earth slag with a neodymium content of 46.3% are obtained from the metal port 6 and the slag discharge port 5 respectively. The iron recovery rate in the NdFeB waste is 93.6%, and the rare earth recovery rate is 93.3%.

[0071] Example 2

[0072] This embodiment proposes a method for efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste. The specific reduction recovery method is as follows:

[0073] NdFeB scrap with a particle size of 50 mesh and electronic scrap with a block size of 40 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron in the mixed material is 21%, the mass fraction of silicon dioxide is 33%, and the mass fraction of calcium oxide is 19%. The mixed material is added into the top-blown smelting furnace 1 through the feeding port 4. The temperature in the furnace is 1422 ° C, the mass percentage of oxygen in the oxygen-enriched process air is 25%, and the flue gas is molten. The residual oxygen concentration is 3%, and the oxidation smelting is carried out for 40 minutes to obtain crude copper with a copper content of 92.5%, and the copper recovery rate is 92.1%; the ratio of reducing natural gas to process air is controlled to be 1:12, and the reduction smelting is carried out for 20 minutes. After static sedimentation for 10 minutes, an iron-rich phase with an iron content of 91.9% and a rare earth slag with a neodymium content of 46.7% are obtained from the metal port 6 and the slag discharge port 5 respectively. The iron recovery rate in the NdFeB waste is 90.2%, and the rare earth recovery rate is 93.5%.

[0074] Example 3

[0075] This embodiment proposes a method for efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste. The specific reduction recovery method is as follows:

[0076] The NdFeB scrap with a particle size of 100 mesh and the electronic scrap with a block size of 30 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron w(Fe) in the mixed material is 23%, the mass fraction of silicon dioxide w(SiO2) is 33%, and the mass fraction of calcium oxide w(CaO) is 19%. The mixed material is added into the top-blown smelting furnace 1 through the feeding port 4. The temperature in the furnace is 1455°C, the mass percentage of oxygen in the oxygen-enriched process air is 30%, and the flue gas is heated to 1000°C. The residual oxygen concentration was 2%, and the oxidation smelting was carried out for 40 minutes to obtain crude copper with a copper content of 92.3%, and the copper recovery rate was 92.6%. The ratio of reducing natural gas to process air was controlled to be 1:11, and the reduction smelting was carried out for 25 minutes. After static sedimentation for 15 minutes, an iron-rich phase with an iron content of 91.7% and a rare earth slag with a neodymium content of 46.8% were obtained from the metal port 6 and the slag discharge port 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 efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste. The specific reduction recovery method is as follows:

[0079] NdFeB scrap with a particle size of 100 mesh and electronic scrap with a block size of 20 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron in the mixed material is 27%, the mass fraction of silicon dioxide is 32%, and the mass fraction of calcium oxide is 19%. The mixed material is added into the top-blown smelting furnace 1 through the feeding port 4. The temperature in the furnace is 1465 ° C, the mass percentage of oxygen in the oxygen-enriched process air is 35%, and the flue gas is molten. The residual oxygen concentration was 2%, and the oxidation smelting was carried out for 40 minutes to obtain crude copper with a copper content of 92.4%, and the copper recovery rate was 93.3%; the ratio of reducing natural gas to process air was controlled to be 1:11, and the reduction smelting was carried out for 25 minutes. After static sedimentation for 18 minutes, an iron-rich phase with an iron content of 92.5% and a rare earth slag with a neodymium content of 46.5% were obtained from the metal port 6 and the slag discharge port 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 efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste. The specific reduction recovery method is as follows:

[0082] The NdFeB scrap with a particle size of 100 mesh and the electronic scrap with a block size of 10 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron w(Fe) in the mixed material is 26%, the mass fraction of silicon dioxide w(SiO2) is 32%, and the mass fraction of calcium oxide w(CaO) is 18%. The mixed material is added into the top-blown smelting furnace 1 through the feeding port 4. The temperature in the furnace is 1485°C, the mass percentage of oxygen in the oxygen-enriched process air is 40%, and the flue gas is heated to 1500 ℃. The residual oxygen concentration was 2%, and the oxidation smelting was carried out for 40 minutes to obtain crude copper with a copper content of 91.4%, and the copper recovery rate was 92.0%; the ratio of reducing natural gas to process air was controlled to be 1:10, and the reduction smelting was carried out for 25 minutes. After static sedimentation for 25 minutes, an iron-rich phase with an iron content of 94.3% and a rare earth slag with a neodymium content of 47.2% were obtained from the metal port 6 and the slag discharge port 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 the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for efficiently recovering valuable elements by synergistically smelting NdFeB waste and electronic waste, characterized in that: The steps include: S1. Dismantle, sort, crush, and ball-mill pretreatment of NdFeB scrap and electronic scrap. Mix the pretreated powdered NdFeB scrap and fine granular electronic scrap with a slag-forming agent and a solid reducing agent. Use a feeding system to feed the mixture into a top-blown smelting furnace from the top charging port of the furnace. S2. Natural gas and oxygen-enriched process air are introduced through the smelting lance. The mass percentage of oxygen in the oxygen-enriched process air is 21% to 50%. The temperature in the smelting furnace is controlled to be 1300℃ to 1600℃. During this process, a weak oxidizing atmosphere is controlled, and the mixed material is in a highly dispersed floating state and falls from the top of the furnace to the bottom of the furnace. The fine granular material is fully in contact with the weak oxidizing atmosphere, creating good oxidation reaction kinetic conditions, so that the iron and rare earth in the mixed material are quickly oxidized into oxides and enter the slag, while the copper is not oxidized and captures rare and precious metals such as gold and silver in the 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 stratification, the crude copper layer is discharged from the metal port; S4. Adding a solid reducing agent to the smelting furnace again and introducing reducing gas and process air to adjust the residual oxygen concentration of the flue gas to 1% to 3%, controlling the smelting furnace to have a strong reducing atmosphere, and controlling the temperature in the smelting furnace to be 1300° C. to 1600° C. to perform strong reducing 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 is fully mixed and contacted with the solid reducing agent in the molten pool. By controlling the amount of the solid reducing agent and the ratio of the reducing gas to the process air, bubbles are generated in the reducing slag, further strengthening the reduction reaction kinetics, and reducing the iron oxides in the rare earth slag to metallic iron. The iron has a greater density than the rare earth slag and sinks to the bottom of the furnace. S5. After the reduction process is completed, stop adding the reducing agent, lift the smelting lance out of the molten pool for insulation, and allow the slag to naturally settle and stratify. The iron and rare earth slag are discharged from the metal port and slag port respectively.

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

3. The method according to claim 1, characterized in that The particle size of the NdFeB scrap is below 50 mesh, and the block size of the electronic scrap is 10 mm to 50 mm.

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

5. The method according to claim 4, characterized in that 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%; the mixture is added to the top-blown smelting furnace through the feeding port at the top of the furnace using a feeding system at a speed of 2t / h to 4t / h.

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

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

8. The method according to claim 1, characterized in that The weak oxidizing atmosphere is a natural gas and oxygen-enriched process air volume ratio of 1:24 to 1:30; the reducing atmosphere is a reducing gas and process air volume ratio of 1:10 to 1:

12.

9. The method according to claim 1, characterized in that The reduced smelting flue gas passes through the flue gas secondary combustion system, waste heat recovery system, flue gas rapid cooling system, activated carbon injection system, dust removal system, and desulfurization system before meeting the emission standards.

10. The method according to claim 1, characterized in that The bubbles are generated during the strong reduction reaction when the reducing gas cannot escape in time in the slag with high viscosity; The organic matter contained in the electronic waste has a high calorific value and can provide heat for the co-smelting of the NdFeB waste when burned; The NdFeB scrap has a high iron content and can be used to supplement the iron element for slag formation when smelted in conjunction with electronic scrap, without the need to add additional iron slag forming agents. The slag is statically layered so that the iron metal particles can quickly settle at the edge of the bubble layer of the slag.

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