Method for recovering valuable elements through oxygen-controlled roasting of neodymium iron boron waste and electronic waste

Abstract

The invention provides a method for recovering valuable elements by cooperating neodymium iron boron waste with electronic waste through oxygen-controlled roasting, which comprises the following steps: mixing powdery neodymium iron boron waste, fine granular electronic waste, a slag former and a solid heat generating agent, and enabling the mixed material to fall to the bottom of a furnace in a drifting state from a furnace top charging hole; rare earth in the mixed material is quickly oxidized, iron is selectively oxidized into magnetic ferroferric oxide, copper is not oxidized, rare earth oxide and ferroferric oxide enter a slag phase, and copper captures gold, silver and other rare and precious metals in the electronic waste to form crude copper. And crude copper sinks into the furnace bottom due to higher slag phase density. And after standing and layering, crude copper and a slag phase are respectively discharged, then the slag phase is subjected to magnetic separation to separate out ferroferric oxide, and an iron-rich phase and a rare earth-rich phase are obtained. According to the method, ingredients of specific slag types are used for burdening, oxygen-controlled roasting is carried out in the top-blown furnace, three products of crude copper rich in rare and precious metals, a rare earth-rich phase and an iron-rich phase are synchronously obtained, 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 invention relates to the technical field of recycling NdFeB waste and electronic waste, and in particular to a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with 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 listed 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 methods to separate rare earths and iron. However, these methods do not fully utilize the separated iron, consume high energy consumption per furnace, and produce large amounts of wastewater. Most electronic waste treatment processes use pyrometallurgical processes, including closed blast furnace roasting, Ausmelt furnace roasting, flash furnace roasting, Kaldo furnace roasting, side-blown furnace roasting, and bottom-blown furnace roasting. Due to the inherent characteristics of these smelting processes, the comprehensive recovery of valuable metals from electronic waste still suffers from low recovery rates, lengthy 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 valuable elements from NdFeB waste and electronic waste by oxygen-controlled roasting to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste, comprising the following steps:

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

[0009] S2. Natural gas and oxygen-enriched process air are introduced through the roasting lance. The mass percentage of oxygen in the oxygen-enriched process air is 25% to 50%. The temperature in the roasting furnace is controlled to be 500℃ to 1000℃. 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 rare earth in the mixed material is rapidly oxidized, and the iron is selectively oxidized to magnetic ferroferric oxide and enters the slag. 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 roasting has a higher density than the slag and sinks to the bottom of the furnace. After standing and stratifying, the crude copper and slag phases reach a certain height and are discharged from the metal port and slag port respectively.

[0011] S4. The discharged slag phase is subjected to magnetic separation to obtain a rare earth-rich phase and an iron-rich phase. The roasting flue gas is treated to meet emission standards.

[0012] 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.

[0013] Furthermore, the particle size of the NdFeB scrap and the slag-forming agent is 50 mesh or less, and the block size of the electronic scrap is 10 mm to 50 mm.

[0014] Furthermore, the slagging agent is at least one of SiO2 and CaO.

[0015] Furthermore, the mass fraction of iron w(Fe) in the mixture is 20% to 30%, the mass fraction of silicon dioxide w(SiO2) is 20% to 35%, and the mass fraction of calcium oxide w(CaO) is 15% to 25%.

[0016] Furthermore, the speed of adding the mixed material from the feeding port on the top of the furnace is 2t / h to 4t / h.

[0017] Furthermore, the NdFeB scrap has a high iron content, and when it is co-roasted with electronic scrap, it can supplement the iron element for slagging during the roasting of the electronic scrap, without the need to add an additional iron slagging agent.

[0018] Furthermore, the solid heating agent is both a fuel and a reducing agent, and is preferably solid coke or diced coal.

[0019] Furthermore, in the oxidizing atmosphere, the ratio of natural gas to oxygen-enriched process air volume is 1:14 to 1:16, and the residual oxygen concentration of the flue gas is 7% to 9%.

[0020] Furthermore, the roasting 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.

[0021] Furthermore, the organic matter contained in the electronic waste has a high calorific value, and when burned, it can provide heat for the co-roasting of the NdFeB waste, thereby reducing energy consumption.

[0022] Furthermore, the organic matter contained in the electronic waste has a high calorific value, which can provide heat for the co-roasting of the NdFeB waste during combustion, thereby greatly reducing energy consumption.

[0023] Furthermore, sampling observation and analysis are performed through a probe rod to determine the oxidation end point.

[0024] The present invention provides a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste, which has the following characteristics and advantages:

[0025] (1) This method is to mix powdered NdFeB waste and fine-grained electronic waste with a slag-forming agent and a solid heating agent, and the mixture is fed into the furnace from the charging port on the top. The fine-grained mixed waste is in a highly dispersed state during the falling process and is fully in contact with the high-temperature oxidizing atmosphere in the furnace, creating good oxidation reaction kinetic conditions and rapidly undergoing oxidation reaction, so that rare earths are rapidly oxidized, and iron is selectively oxidized into magnetic ferroferric oxide and enters the slag phase, while the copper in the electronic waste is not oxidized, and forms a crude copper metal melt with rare and precious metals such as gold and silver in the electronic waste and falls into the molten pool at the bottom of the furnace. After standing and stratification, it is separated from the rare earth-containing slag in the upper layer.

[0026] (2) The mixture melt is further fully oxidized under the stirring of the airflow at the outlet of the spray gun. The NdFeB scrap has a high iron content. When co-roasted with electronic scrap, it can supplement the iron element of the electronic scrap to form slag, 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-roasting of the NdFeB scrap, greatly reducing energy consumption.

[0027] 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

[0028] 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.

[0029] Figure 1 A schematic flow chart of a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste, as proposed by the present invention;

[0030] Figure 2 This is a schematic structural diagram of a top-blown roasting furnace used in the embodiments to recover rare earths, copper, gold and silver from NdFeB waste and electronic waste using the recovery method proposed by the present invention.

[0031] The markings in the accompanying drawings are: 1. top-blown roasting furnace; 2. roasting lance; 3. detection rod; 4. feeding port; 5. slag discharge port; 6. metal port. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The present invention provides a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste, such as Figure 1 As shown, the following steps are included:

[0036] S1. Dismantle, sort, crush, and ball-mill NdFeB scrap and electronic scrap for pretreatment. Mix the pretreated powdered NdFeB scrap and fine granular electronic scrap with a slag-forming agent and a solid heating agent. Use a feeding system to feed the mixture into the top-blown roasting furnace from the top charging port.

[0037] S2. Natural gas and oxygen-enriched process air are introduced through the roasting lance. The mass percentage of oxygen in the oxygen-enriched process air is 25% to 50%. The temperature in the roasting furnace is controlled to be 500℃ to 1000℃. 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 rare earth in the mixed material is rapidly oxidized, and the iron is selectively oxidized to magnetic ferroferric oxide and enters the slag. The copper is not oxidized and captures rare and precious metals such as gold and silver in the electronic waste to form crude copper.

[0038] S3. The crude copper produced by weak oxidation roasting has a higher density than the slag and sinks to the bottom of the furnace. After standing and stratifying, the crude copper and slag phases reach a certain height and are discharged from the metal port and slag port respectively.

[0039] S4. The discharged slag phase is subjected to magnetic separation to obtain a rare earth-rich phase and an iron-rich phase. The roasting flue gas is treated to meet emission standards.

[0040] The above recovery process is completed with the help of a top-blown roasting furnace 1, the structural diagram of which is shown in FIG. Figure 2 As shown, a top-blown roasting furnace 1 includes 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 roasting lance 2 and a probe 3 provided inside the furnace body, extending through the inner wall of the furnace body and to the bottom of the furnace body. The roasting 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 in the furnace and analyze the composition and morphology of the reduced slag at the upper portion of the probe 3 to determine the reduction endpoint and reduction time. In other embodiments, other roasting furnaces that can achieve the above-mentioned purposes may also be selected as needed.

[0041] As an embodiment of the present invention, in step S1, 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.

[0042] As an embodiment of the present invention, in step S1, the particle size of the NdFeB scrap and the slag-forming agent is 50 mesh or less, and the block size of the electronic scrap is 10 mm to 50 mm.

[0043] As an embodiment of the present invention, in step S1, the slag-forming agent is at least one of SiO2 and CaO.

[0044] As an embodiment of the present invention, in step S1, the mass fraction of iron w(Fe) in the mixture is 20% to 30%, the mass fraction of silicon dioxide w(SiO2) is 20% to 35%, and the mass fraction of calcium oxide w(CaO) is 15% to 25%.

[0045] As an embodiment of the present invention, in step S1, the mixed material is added from the feeding port on the top of the furnace at a speed of 2 t / h to 4 t / h.

[0046] As an embodiment of the present invention, in step S1, the NdFeB scrap has a high iron content. When it is co-roasted 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.

[0047] As an embodiment of the present invention, in step S1, the solid exothermic agent is both a fuel and a reducing agent, preferably solid coke or diced coal.

[0048] 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 heat for the co-roasting of the NdFeB waste during combustion, thereby reducing energy consumption.

[0049] As an embodiment of the present invention, in step S2, the oxidizing atmosphere is a natural gas to oxygen-enriched process air volume ratio of 1:14 to 1:16, and the flue gas residual oxygen concentration is 7% to 9%.

[0050] As an embodiment of the present invention, in steps S2 and S3, the roasting flue gas passes through the flue gas secondary combustion system, waste heat recovery system, flue gas quenching system, activated carbon injection system, dust removal system, and desulfurization system before meeting the emission standards.

[0051] As an embodiment of the present invention, in step S2, sampling, observation, analysis and determination of the oxidation end point are performed by using a probe rod.

[0052] In the above technical solution, the characteristics of NdFeB scrap that has high iron content and low calorific value and electronic scrap that has low iron content but high calorific value are utilized. By mixing powdered NdFeB scrap, fine-granular electronic scrap with quartz stone, limestone (the main component of limestone is calcium carbonate CaCO3, which is thermally decomposed into CaO at high temperature in the furnace) and solid heating agent, NdFeB scrap can supplement the iron element of electronic scrap for slag formation, without the need to add additional iron slag forming agent. The high calorific value of electronic scrap can provide heat for the co-roasting of NdFeB scrap when burned, greatly reducing energy consumption. The mixed material is added to the top-blown roaster. As the powdered material falls, it fully contacts the oxidizing atmosphere in the furnace, creating favorable oxidation reaction kinetics. This allows the rare earth elements in the NdFeB scrap to be rapidly oxidized, with the iron selectively oxidized to magnetic ferroferric oxide, which enters the slag. The copper in the electronic scrap remains unoxidized and captures valuable metals such as gold and silver to form a crude copper alloy melt. This crude copper alloy melt, denser than the rare earth slag, rapidly descends to the furnace bottom, where it settles and separates from the rare earth slag after stratification. This process fully utilizes the high iron content in NdFeB scrap and the high calorific value of electronic scrap to recover copper from electronic scrap, avoiding the need for additional iron supplementation during roasting due to the low iron content of electronic scrap. After the roasting reaction is completed, stop adding materials, lift the smelting lance out of the molten pool for insulation, allow the slag to stand and stratify, and discharge the crude copper metal melt and the rare earth-containing slag phase from the metal port and slag port respectively. Finally, the rare earth-containing slag phase is magnetically separated to separate the ferroferric oxide and obtain the iron-rich phase and the rare earth-rich phase.

[0053] The following is a further description of the method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste and electronic waste proposed by the present invention in conjunction with specific embodiments:

[0054] Example 1

[0055] This embodiment proposes a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste. The specific reduction recovery method is as follows:

[0056] Neodymium iron boron 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 w(Fe) in the mixed material after mixing is 20%, the mass fraction of silicon dioxide w(SiO2) is 31%, and the mass fraction of calcium oxide w(CaO) is 17%. The mixed material is added into a top-blown roasting furnace 1 through a feed port 4. The temperature in the furnace is 800°C, the mass percentage of oxygen in the oxygen-enriched process air is 21%, and the oxidation roasting is carried out for 40 minutes. The ratio of roasting natural gas to oxygen-enriched process air is 1:14, the residual oxygen concentration of the flue gas is 7%, and the mixture is allowed to settle for 10 minutes. A blister copper with a copper content of 93.6% is obtained, and the copper recovery rate is 92.3%. An iron-rich phase with an iron content of 65.6% and a rare earth slag with a neodymium content of 45.3% are obtained. The iron recovery rate in the neodymium iron boron scrap is 95.6%, and the rare earth recovery rate is 93.2%.

[0057] Example 2

[0058] This embodiment proposes a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste. The specific reduction recovery method is as follows:

[0059] Neodymium iron boron 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 w(Fe) in the mixed material after mixing is 21%, the mass fraction of silicon dioxide w(SiO2) is 31%, and the mass fraction of calcium oxide w(CaO) is 18%. The mixed material is added into a top-blown roasting furnace 1 through a feed port 4. The temperature in the furnace is 850°C, the mass percentage of oxygen in the oxygen-enriched process air is 25%, and the oxidation roasting is carried out for 40 minutes. The ratio of roasting natural gas to oxygen-enriched process air is 1:14, the residual oxygen concentration of the flue gas is 8%, and the material is allowed to settle for 10 minutes. Crude copper with a copper content of 92.9% is obtained, and the copper recovery rate is 92.8%. An iron-rich phase with an iron content of 65.7% and a rare earth slag with a neodymium content of 45.5% are obtained. The iron recovery rate in the neodymium iron boron scrap is 94.5%, and the rare earth recovery rate is 93.5%.

[0060] Example 3

[0061] This embodiment proposes a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste. The specific reduction recovery method is as follows:

[0062] Neodymium iron boron waste with a particle size of 50 mesh and electronic waste 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 after mixing is 21%, 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 a top-blown roasting furnace 1 through a feed port 4. The temperature in the furnace is 900° C., the mass percentage of oxygen in the oxygen-enriched process air is 30%, and the oxidation roasting is carried out for 40 minutes. The ratio of roasting natural gas to oxygen-enriched process air is 1:15, the residual oxygen concentration of the flue gas is 8%, and the material is allowed to settle for 10 minutes. Crude copper with a copper content of 93.6% is obtained, and the copper recovery rate is 91.2%. An iron-rich phase with an iron content of 66.3% and a rare earth slag with a neodymium content of 45.7% are obtained. The iron recovery rate in the neodymium iron boron waste is 95.2%, and the rare earth recovery rate is 94.8%.

[0063] Example 4

[0064] This embodiment proposes a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste. The specific reduction recovery method is as follows:

[0065] Neodymium iron boron waste with a particle size of 100 mesh and electronic waste with a block size of 20 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron w(Fe) in the mixed material after mixing is 22%, the mass fraction of silicon dioxide w(SiO2) is 32%, and the mass fraction of calcium oxide w(CaO) is 19%. The mixed material is added into a top-blown roasting furnace 1 through a feed port 4. The temperature in the furnace is 950° C., the mass percentage of oxygen in the oxygen-enriched process air is 40%, and the oxidizing roasting is carried out for 40 minutes. The ratio of roasting natural gas to oxygen-enriched process air is 1:15, the residual oxygen concentration of the flue gas is 9%, and the mixture is allowed to settle for 10 minutes. A blister copper with a copper content of 94.5% is obtained, and the copper recovery rate is 91.8%. An iron-rich phase with an iron content of 66.8% and a rare earth slag with a neodymium content of 45.8% are obtained. The iron recovery rate in the neodymium iron boron waste is 95.4%, and the rare earth recovery rate is 94.9%.

[0066] Example 5

[0067] This embodiment proposes a method for recovering valuable elements by oxygen-controlled roasting of NdFeB waste in conjunction with electronic waste. The specific reduction recovery method is as follows:

[0068] Neodymium iron boron waste with a particle size of 100 mesh and electronic waste with a block size of 20 mm are mixed with quartz stone, limestone and coke. The mass fraction of iron w(Fe) in the mixed material after mixing is 23%, 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 a top-blown roasting furnace 1 through a feed port 4. The temperature in the furnace is 1000° C., the mass percentage of oxygen in the oxygen-enriched process air is 45%, and the oxidation roasting is carried out for 40 minutes. The ratio of roasting natural gas to oxygen-enriched process air is 1:16, the residual oxygen concentration of the flue gas is 9%, and the material is allowed to settle for 10 minutes. A blister copper with a copper content of 95.3% is obtained, and the copper recovery rate is 90.6%. An iron-rich phase with an iron content of 67.1% and a rare earth slag with a neodymium content of 46.3% are obtained. The iron recovery rate in the neodymium iron boron waste is 96.4%, and the rare earth recovery rate is 96.7%.

[0069] 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 recovering valuable elements by oxygen-controlled roasting of 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 heating agent. Use a feeding system to feed the mixture into a top-blown roasting furnace from the top feeding port of the furnace. S2. Natural gas and oxygen-enriched process air are introduced through a roasting lance, with the mass percentage of oxygen in the oxygen-enriched process air being 21% to 50%. The temperature in the roasting furnace is controlled to be 500°C to 1000°C. During this process, a weak oxidizing atmosphere is controlled, and the mixed material is highly dispersed and floats from the top of the furnace to the bottom of the furnace. The fine particles are fully exposed to the weak oxidizing atmosphere, creating favorable oxidation reaction kinetic conditions, so that the rare earth in the mixed material is rapidly oxidized, and the iron is selectively oxidized to magnetic ferroferric oxide and enters the slag. The copper is not oxidized and captures the gold and silver rare precious metals in the electronic waste to form crude copper; S3. The crude copper produced by weak oxidation roasting has a higher density than the slag and sinks to the bottom of the furnace. After standing and stratification, the crude copper and slag phases are discharged from the metal port and slag port respectively. S4. Magnetic separation is performed on the discharged slag phase to obtain a rare earth-rich phase and an iron-rich phase.

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 waste and the slag-forming agent is 50 mesh or less, and the block size of the electronic waste 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.

5. The method according to claim 4, characterized in that The mass fraction of iron w(Fe) in the mixture is 20% to 30%, the mass fraction of silicon dioxide w(SiO2) is 20% to 35%, and the mass fraction of calcium oxide w(CaO) is 15% to 25%; the mixture is added at a speed of 2t / h to 4t / h from the feeding port on the top of the furnace.

6. The method according to claim 1, characterized in that The solid heat-generating agent is both a fuel and a reducing agent.

7. The method according to claim 6, characterized in that The solid heating agent is solid coke or diced coal.

8. The method according to claim 1, characterized in that In the oxidizing atmosphere, the ratio of natural gas to oxygen-enriched process air volume is 1:14 to 1:16, and the residual oxygen concentration of the flue gas is 7% to 9%.

9. The method according to claim 8, characterized in that The roasting 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 NdFeB scrap has a high iron content and can supplement the iron element for slag formation when co-roasted with electronic scrap, without the need to add additional iron slag-forming agents. The organic matter in the electronic scrap has a high calorific value and can provide heat for the co-roasting of the NdFeB scrap when burned.

Images