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

Abstract

The invention provides a method for recovering valuable elements through reduction smelting of neodymium iron boron waste and electronic waste, which comprises the following steps: proportioning powdery neodymium iron boron waste, fine granular electronic waste, a slag former and a solid reducing agent, and carrying out reduction smelting on the mixture by using a top-blown smelting furnace; by controlling the conditions of the reduction process, copper and iron oxides in the mixed material are reduced into metal copper and metal iron, the metal copper and the metal iron are gathered with gold, silver and other rare and precious metals in the electronic waste to form a copper-iron precious metal alloy, rare earth oxides are not reduced and reserved in a slag layer, and the density of copper-iron precious metal alloy particles is larger than that of rare earth slag; according to the method, the rare earth slag is separated from the metal port and the slag port, the rare earth slag rapidly descends in the slag layer and sinks to the bottom of the furnace, copper-iron precious metal alloy melt and the rare earth slag are discharged from the metal port and the slag port respectively after standing layering, finally, synchronous recovery of rare earth in neodymium iron boron waste and copper, gold and silver in 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 of NdFeB and electronic waste, and in particular to a method for recovering valuable elements by reducing and smelting 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 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, including 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 limitations of these smelting processes, the comprehensive recovery of valuable metals from electronic waste using these processes 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 rare earth and valuable metals from NdFeB waste and electronic waste 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 reducing and smelting 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 reducing and smelting NdFeB scrap in conjunction with electronic scrap, comprising the following steps:

[0008] S1. Dismantle, sort, crush, ball mill and other pretreatments to 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 the top-blown smelting furnace from the charging port on the top of the furnace.

[0009] S2. Use the smelting lance to introduce reducing gas and process air into the smelting furnace, control the temperature in the smelting furnace to 1300℃~1600℃, and the mixed material floats from the top of the furnace to the bottom in a highly dispersed floating state. During this process, control the reducing atmosphere to make the oxygen partial pressure of the smelting system in the furnace lower than 10 -20 Atm, as the material falls, the majority of the copper and iron oxides are reduced to metallic copper and iron, which form a copper-iron precious metal alloy with the gold and silver in the electronic scrap. However, the rare earth oxides remain unreduced and form a rare earth slag phase with the slag-forming agent. As the high-temperature melt obtained by reduction in the smelting furnace falls to the bottom of the furnace, it is rapidly drawn into the molten pool by the intense stirring of the airflow at the smelting lance outlet, where it is thoroughly mixed with the solid reducing agent within 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 reducing slag, further enhancing the reduction reaction kinetics. This allows the small amount of unreduced copper and iron oxides to be further reduced to metallic copper and iron, and captures precious metals such as gold and silver in the slag to form a copper-iron precious metal alloy.

[0010] S3. After the reduction process is completed, stop adding materials and reducing agents, lift the smelting lance out of the molten pool for heat preservation, let the slag stand and stratify, and discharge the copper-iron precious metal alloy melt and rare earth slag from the metal port and slag port respectively.

[0011] 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.

[0012] Furthermore, the particle size of the NdFeB scrap is 50 mesh or less, and the block size of the electronic scrap is 10 mm to 50 mm.

[0013] Furthermore, the slag-forming agent is at least one of SiO2 and CaO, and its particle size is 1mm to 10mm.

[0014] 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%.

[0015] Furthermore, the speed of adding the mixed material from the feeding port on the top of the furnace is 2t / h to 6t / h.

[0016] 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.

[0017] Furthermore, the reducing gas and solid reducing agent can be used as fuel.

[0018] Furthermore, the reducing gas is one or more of carbon monoxide, hydrogen, natural gas, and shale gas, preferably natural gas.

[0019] Furthermore, the solid reducing agent is at least one of coke and coal.

[0020] Furthermore, the reducing atmosphere is such that the ratio of reducing gas to process air volume is 1:10 to 1:15, and the residual oxygen concentration of the flue gas is 1% to 4%.

[0021] 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.

[0022] Furthermore, the bubbles are generated during the strong reduction reaction when the reducing gas cannot escape in time in the slag with high viscosity.

[0023] Furthermore, the slag static stratification allows alloy particles to quickly settle in the bubble layer of the slag, greatly shortening the static sedimentation time.

[0024] 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.

[0025] Furthermore, the reduction end point is determined by sampling, observing and analyzing the morphology of the reduced slag using a probe rod.

[0026] The present invention provides a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap, which has the following characteristics and advantages:

[0027] (1) This method involves mixing powdered NdFeB scrap and fine-granular electronic scrap with a slag-forming agent and a solid reducing agent. The mixture is fed into the furnace from the top charging port. The fine-granular material is highly dispersed during its fall, fully contacts the high-temperature reducing gas in the furnace, and rapidly undergoes a reduction reaction, forming a metal melt that falls into the molten pool at the bottom of the furnace. Furthermore, NdFeB scrap has a high iron content, and when co-smelted with electronic scrap, it can supplement the iron element for slag formation without the need for additional iron slag-forming agents. The organic matter in the electronic scrap itself has a high calorific value, and when burned, it can provide some heat for the co-smelting of NdFeB scrap, greatly reducing energy consumption.

[0028] (2) The unreduced iron oxides and copper oxides fall into the molten pool and are 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 torch, creating good reaction kinetic conditions, so that the iron oxides and copper oxides in the mixed smelting slag are quickly and completely reduced to metallic iron and metallic copper. The two are aggregated with rare and precious metals such as gold and silver in the electronic waste to form copper-iron precious metal alloys, while the rare earth oxides are not reduced and continue to remain in the slag layer.

[0029] (3) The copper-iron precious metal alloy particles have a higher density than the rare earth slag and can quickly sink into the metal layer in the slag foam layer. After static stratification, the copper-iron precious metal alloy melt and the rare earth slag are discharged from the metal port and the slag port respectively, without the need for forced separation by ultra-gravity slag-gold melting and magnetic separation.

[0030] 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

[0031] 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.

[0032] Figure 1 This is a flow chart of a method proposed by the present invention for recovering valuable elements by reducing and smelting NdFeB waste in conjunction with electronic waste;

[0033] 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.

[0034] 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

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The present invention provides a method for recovering valuable elements by reducing and smelting NdFeB waste in conjunction with electronic waste, such as Figure 1 As shown, the following steps are included:

[0039] S1. Dismantle, sort, crush, ball mill and other pretreatments to 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 the top-blown smelting furnace from the charging port on the top of the furnace.

[0040] S2. Reducing gas and process air are introduced into the smelting furnace by using a smelting lance, and the temperature in the smelting furnace is controlled to be 1300°C to 1600°C. The mixed material falls from the top of the furnace to the bottom in a highly dispersed floating state. During this process, the reducing atmosphere is controlled to make the oxygen partial pressure of the smelting system in the furnace lower than 10atm to 20atm. As the material falls, most of the copper and iron oxides are reduced to metallic copper and metallic iron, which form copper-iron precious metal alloys with gold and silver in the electronic scrap, while the rare earth oxides are not reduced and form a rare earth slag phase with the slag-making agent. When the high-temperature melt obtained by reduction in the smelting furnace falls to the bottom of the smelting furnace, it is rapidly drawn into the molten pool under the strong stirring of the airflow at the outlet of the smelting spray gun and is fully and evenly mixed with the solid reducing agent inside the molten pool. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated inside the reducing slag, which further strengthens the kinetic conditions of the reduction reaction, so that a small part of the unreduced copper and iron oxides are further reduced to metallic copper and metallic iron, and precious metals such as gold and silver in the slag are captured to form copper-iron precious metal alloys.

[0041] S3. After the reduction process is completed, stop adding materials and reducing agents, lift the smelting lance out of the molten pool for heat preservation, let the slag stand and stratify, and discharge the copper-iron precious metal alloy melt and rare earth slag from the metal port and slag port respectively.

[0042] 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 2As 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 inside the furnace body, extending through the inner wall and to the bottom of the furnace body. 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 in the furnace and the composition and morphology of the reduced slag at the upper portion of the probe 3, thereby analyzing and determining the reduction endpoint and reduction time. In other embodiments, other smelting furnaces that can achieve the above-mentioned purposes may be selected as needed.

[0043] 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.

[0044] As an embodiment of the present invention, in step S1, the materials entering the furnace need to be pretreated so that the particle size of the NdFeB scrap is 50 mesh or less, and the block size of the electronic scrap is 10 mm to 50 mm.

[0045] 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.

[0046] 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.

[0047] 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%.

[0048] 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 6 t / h.

[0049] As an embodiment of the present invention, in step S1 , the reducing gas and the solid reducing agent serve as both the fuel and the reducing agent.

[0050] As an embodiment of the present invention, in step S1, the reducing gas is one or more of carbon monoxide, hydrogen, natural gas, and shale gas, preferably natural gas.

[0051] As an embodiment of the present invention, in step S1, the solid reducing agent is at least one of coke and coal.

[0052] 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-smelting of the NdFeB waste when burned, greatly reducing energy consumption.

[0053] As an embodiment of the present invention, in step S2, the reducing atmosphere is a reducing gas to process air volume ratio of 1:10 to 1:15, and the flue gas residual oxygen concentration is 1% to 4%.

[0054] As an embodiment of the present invention, in step S2, 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.

[0055] As an embodiment of the present invention, in step S2, bubbles are generated during a strong reduction reaction when reducing gas cannot escape in time from the slag with high viscosity.

[0056] 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.

[0057] As an embodiment of the present invention, in step S2, sampling, observation and analysis of the morphology of the reduced slag are performed by a probe rod to determine the reduction end point.

[0058] The above technical solution takes advantage of the high iron content and low calorific value of NdFeB scrap, while electronic scrap has a low iron content but high calorific value. By mixing NdFeB scrap and 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 also 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 melting furnace, the powdered material fully contacts the reducing gas in the furnace as it falls, creating favorable kinetic conditions for the reduction reaction, which rapidly undergoes the reduction reaction. Unreduced iron and copper oxides fall to the furnace bottom and, stirred by the airflow from the smelting lance outlet, are rapidly drawn into the molten pool, where they react with the solid reducing agent within the pool to form metallic iron and copper. These metals also capture precious metals such as gold and silver from the electronic scrap, forming a copper-iron precious metal alloy. 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, while 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 high viscosity of high-silicon, high-calcium slag, a foam layer is easily formed in the molten slag during strong reduction smelting. This increases the slag's specific surface area and enhances the kinetics of the gas-solid two-phase reduction reaction, facilitating the reduction reaction. Encapsulated by the copper-iron alloy, the precious metals such as gold and silver from the electronic scrap aggregate into a molten alloy. The molten alloy, which is denser than the rare earth slag, rapidly descends through the foam layer to the furnace bottom, forming a copper-iron precious metal alloy. After the reduction process is completed, stop adding materials and reducing agents, lift the smelting lance out of the molten pool for insulation, allow the slag to stand and stratify, and the copper-iron precious metal alloy melt and rare earth slag are discharged from the metal port and slag port respectively.

[0059] The following is a further description of the method for recovering valuable elements by reducing and smelting NdFeB waste in conjunction with electronic waste, as proposed by the present invention, with reference to specific embodiments:

[0060] Example 1

[0061] This embodiment proposes a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap. The specific reduction and recovery method is as follows:

[0062] Neodymium iron boron 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 w(Fe) in the mixed material after mixing is 25%, 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 smelting furnace 1 through a feed port 4. The temperature in the furnace is 1385° C. and the residual oxygen concentration in the flue gas is 4%. After smelting for 60 minutes under the reducing conditions and then standing and settling for 15 minutes, a copper-iron precious metal alloy rich in rare earth metals with a copper content of 52.5% and an iron content of 45.8% and a rare earth slag with a neodymium content of 42.3% are obtained from a metal port 6 and a slag discharge port 5, respectively. The total recovery rate of rare earths in the neodymium iron boron scrap is 96.5%, and the total recovery rate of copper in the electronic scrap is 97.7%.

[0063] Example 2

[0064] This embodiment proposes a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap. The specific reduction and recovery method is as follows:

[0065] 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 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 smelting furnace 1 through a feed port 4. The temperature in the furnace is 1393° C. and the residual oxygen concentration in the flue gas is 3%. After smelting for 60 minutes under the reducing conditions and then standing and settling for 15 minutes, a copper-iron precious metal alloy rich in rare earth metals with a copper content of 52.9% and an iron content of 45.2% and a rare earth slag with a neodymium content of 42.5% are obtained from a metal port 6 and a slag discharge port 5, respectively. The total recovery rate of rare earths in the neodymium iron boron scrap is 96.7%, and the total recovery rate of copper in the electronic scrap is 97.1%.

[0066] Example 3

[0067] This embodiment proposes a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap. The specific reduction and recovery method is as follows:

[0068] Neodymium iron boron scrap with a particle size of 100 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 23%, the mass fraction of silicon dioxide w(SiO2) is 32%, and the mass fraction of calcium oxide w(CaO) is 21%. The mixed material is added into a top-blown smelting furnace 1 through a feed port 4. The temperature in the furnace is 1433° C. and the residual oxygen concentration in the flue gas is 3%. After smelting for 60 minutes under the reducing conditions and then standing and settling for 15 minutes, a copper-iron precious metal alloy rich in rare earth metals with a copper content of 53.3% and an iron content of 45.1% and a rare earth slag with a neodymium content of 42.8% are obtained from a metal port 6 and a slag discharge port 5, respectively. The total recovery rate of rare earths in the neodymium iron boron scrap is 96.9%, and the total recovery rate of copper in the electronic scrap is 97.5%.

[0069] Example 4

[0070] This embodiment proposes a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap. The specific reduction and recovery method is as follows:

[0071] Neodymium iron boron scrap with a particle size of 100 mesh and 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 after mixing is 23%, the mass fraction of silicon dioxide w(SiO2) is 33%, and the mass fraction of calcium oxide w(CaO) is 21%. The mixed material is added into a top-blown smelting furnace 1 through a feed port 4. The temperature in the furnace is 1453° C. and the residual oxygen concentration in the flue gas is 2%. After smelting for 60 minutes under the reducing conditions and then standing and settling for 15 minutes, a copper-iron precious metal alloy rich in rare earth metals with a copper content of 53.5% and an iron content of 45.3% and a rare earth slag with a neodymium content of 43.3% are obtained from a metal port 6 and a slag discharge port 5, respectively. The total recovery rate of rare earths in the neodymium iron boron scrap is 97.7%, and the total recovery rate of copper in the electronic scrap is 98.1%.

[0072] Example 5

[0073] This embodiment proposes a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap. The specific reduction and recovery method is as follows:

[0074] Neodymium iron boron 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 w(Fe) in the mixed material after mixing is 24%, the mass fraction of silicon dioxide w(SiO2) is 33%, and the mass fraction of calcium oxide w(CaO) is 22%. The mixed material is added into a top-blown smelting furnace 1 through a feed port 4. The temperature in the furnace is 1475° C. and the residual oxygen concentration in the flue gas is 2%. After smelting for 60 minutes under the reducing conditions and then standing and settling for 15 minutes, a copper-iron precious metal alloy rich in rare earth metals with a copper content of 53.3% and an iron content of 45.5% and a rare earth slag with a neodymium content of 43.7% are obtained from a metal port 6 and a slag discharge port 5, respectively. The total recovery rate of rare earths in the neodymium iron boron scrap is 98.4%, and the total recovery rate of copper in the electronic scrap is 98.8%.

[0075] Example 6

[0076] This embodiment proposes a method for recovering valuable elements by reducing and smelting NdFeB scrap in conjunction with electronic scrap. The specific reduction and recovery method is as follows:

[0077] Neodymium iron boron scrap with a particle size of 100 mesh and 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 after mixing is 26%, the mass fraction of silicon dioxide w(SiO2) is 33%, and the mass fraction of calcium oxide w(CaO) is 22%. The mixed material is added into a top-blown smelting furnace 1 through a feed port 4. The temperature in the furnace is 1495° C. and the residual oxygen concentration in the flue gas is 1%. After smelting for 60 minutes under the reducing conditions and then standing and settling for 15 minutes, a copper-iron precious metal alloy rich in rare earths with a copper content of 53.3% and an iron content of 45.5% and a rare earth slag with a rare earth content of 43.9% are obtained from a metal port 6 and a slag discharge port 5, respectively. The total recovery rate of rare earths in the neodymium iron boron scrap is 98.3%, and the total recovery rate of copper in the electronic scrap is 98.9%.

[0078] 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 reducing and smelting NdFeB waste in conjunction with 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. Use the smelting lance to introduce reducing gas and process air into the smelting furnace, control the temperature in the smelting furnace to 1300℃~1600℃, and the mixed material will float from the top of the furnace to the bottom in a highly dispersed floating state. During this process, control the reducing atmosphere to make the oxygen partial pressure of the smelting system in the furnace lower than 10 -20 atm, during the falling process of the material, most of the copper and iron oxides are reduced to metallic copper and metallic iron, which form a copper-iron precious metal alloy with the gold and silver in the electronic scrap, while the rare earth oxides are not reduced and form a rare earth slag phase with the slag-forming agent; when the high-temperature melt obtained by reduction in the smelting furnace falls to the bottom of the smelting furnace, it is rapidly drawn into the molten pool under the strong stirring of the air flow at the outlet of the smelting lance and is fully mixed with the solid reducing agent inside the molten pool. By controlling the amount of solid reducing agent and the ratio of reducing gas to process air, bubbles are generated inside the reduced slag, further strengthening the reduction reaction kinetics, so that a small part of the unreduced copper and iron oxides are further reduced to metallic copper and metallic iron, and the gold and silver precious metals in the slag are captured to form a copper-iron precious metal alloy; S3. After the reduction process is completed, stop adding materials and reducing agents, lift the smelting lance out of the molten pool for heat preservation, let the slag stand and stratify, and discharge the copper-iron precious metal alloy melt and rare earth slag 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 50 mesh or less, 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 at a speed of 2t / h to 6t / h from the feeding port on the top of the furnace.

6. The method according to claim 1, wherein 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.

8. The method according to claim 6, characterized in that The solid reducing agent is at least one of coke and coal.

9. The method according to claim 1, characterized in that The reducing atmosphere has a ratio of reducing gas to process air volume of 1:10 to 1:15, and a flue gas residual oxygen concentration of 1% to 4%.

10. 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.

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