A method for recovering rare earth and valuable metals from NdFeB waste and electronic waste

Abstract

The present invention provides a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste. The method comprises the following steps: mixing NdFeB waste and electronic waste with quartz, limestone and coke, and smelting the mixture in a top-blown smelting furnace; controlling the conditions of the oxidation process so that the rare earth, copper and iron in the mixed smelting slag are oxidized into oxides; controlling the conditions of the reduction process so that the copper oxide in the mixed smelting slag is reduced to metallic copper, while the iron oxide and rare earth oxide are not reduced but retained in the slag layer, thereby achieving the synchronous recovery of valuable metals such as rare earth, copper, gold and silver in NdFeB waste and electronic waste.

Description

Technical Field

[0001] The invention relates to the technical field of recycling NdFeB waste, and in particular to a method for recycling rare earth and valuable metals from NdFeB waste and electronic waste. Background Art

[0002] Rare earth is an important resource, known as industrial MSG, among which NdFeB material is widely used in motor, national defense, aviation, wind power and other industries due to its excellent performance. However, due to the process and equipment life, a large amount of NdFeB waste will be generated. NdFeB waste contains a large amount of rare earth and iron, and has great potential utilization value.

[0003] With the rapid development of science and technology, the update 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 recycled, they will not only cause waste of valuable metals but also pollute the environment.

[0004] At present, most of the treatment methods for NdFeB waste are to separate rare earth and iron by pyrometallurgy and hydrometallurgy, but this method does not make full use of the separated iron; most of the treatment processes for electronic waste adopt pyrometallurgy. The existing pyrometallurgy processes generally include closed blast furnace smelting process, Ausmelt furnace smelting process, flash furnace smelting process, Kaldo furnace smelting process, side-blown furnace smelting process, bottom-blown furnace smelting process, etc. At present, according to the characteristics of these smelting processes themselves, the comprehensive recovery of valuable metals from electronic waste still has the disadvantages of low recovery rate, long process, low raw material adaptability, serious secondary pollution, and high requirements for furnace condition control.

[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 recovering rare earth and valuable metals from NdFeB waste and electronic waste.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste, comprising the following steps:

[0008] S1. Pre-treating NdFeB waste and electronic waste;

[0009] S2. The pretreated NdFeB waste and electronic waste are mixed with a slag-forming agent and coke, wherein the mass fraction of iron w(Fe) in the mixed material is 23-27%, the mass fraction of silicon dioxide w(SiO2) is 35-45%, the mass fraction of calcium oxide w(CaO) is 19-25%, and the mass fraction of aluminum w(Al) is less than 5%;

[0010] S3, after the mixed material in step S2 is put into a top-blown smelting furnace, natural gas and process air or oxygen are introduced to cause the mixed material to undergo an oxidation smelting slag-forming reaction;

[0011] S4. After the oxidation reaction is completed, coke is added to the oxidized slag obtained in step S3, and process air and natural gas are continuously introduced for reduction reaction. The liquid level of the molten pool is measured by a probe rod, and the reduction endpoint and reduction time are determined based on the composition and morphology of the reduced slag at the upper and middle part of the probe rod. The amount of coke added during the reduction reaction is 0.9-1.1 t / h, and the amount of natural gas is 500-550m 3 / h, process air volume is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:10-1:12, and the residual oxygen concentration of flue gas is 1-4%;

[0012] S5. When the reduction end point is reached by the detection rod, the addition of reducing coke is stopped, the amount of natural gas is reduced to the flow rate in the insulation state, and static sedimentation is carried out;

[0013] S6. Carry out copper discharge operation from the copper discharge port; carry out slag discharge operation from the slag discharge port.

[0014] Preferably, in step S3, the amount of coke added during the oxidation smelting process is 0.6-0.8 t / h, and the amount of natural gas is 300-400 m 3 / h, process air volume is 6200-6500m 3 / h, the ratio of natural gas to process air volume is 1:15-1:22, and the residual oxygen concentration in flue gas is 5-10%.

[0015] Preferably, in step S3, the total amount of the mixed material entering the furnace is 2-4 t / h, the rare earth grade in the mixed material is 5-20%, and the copper grade is 3-10%.

[0016] Preferably, in step S5, the flow rate of natural gas during the insulation process is 200-300m 3 / h, process air volume is 2000-3000m 3 / h, the ratio of natural gas to process air volume is 1:10 to ensure full combustion of natural gas.

[0017] Preferably, in step S4, when the reduction end point is reached, the slag sample on the surface of the probe rod is in the shape of wire mesh mercury and the thickness of the foam layer in the molten pool is 300-1000 mm.

[0018] Preferably, in step S4, the reduction time is 5-20 min.

[0019] Preferably, in step S3, the molten pool liquid level is controlled to be 1100 mm during the oxidation smelting process.

[0020] Preferably, in step S5, the static sedimentation time is 10-30 minutes.

[0021] Preferably, in step S2, the slag-forming agent is at least one of quartz stone and limestone.

[0022] Preferably, in step S1, the pretreatment method is crushing and / or granulation.

[0023] The beneficial effects of the present invention are:

[0024] 1. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste provided by the present invention is as follows: the method comprises mixing NdFeB waste and electronic waste with quartz, limestone and coke, and smelting the mixture in a top-blown smelting furnace; by controlling the conditions of the oxidation process, the rare earth, copper and iron in the mixed smelting slag are oxidized into oxides; by controlling the conditions of the reduction process, the copper oxide in the mixed smelting slag is reduced to metallic copper, and the iron oxide and rare earth oxide are not reduced and remain in the slag layer. Valuable metals such as gold and silver in the electronic waste are aggregated into crude copper particles rich in gold and silver under the wrapping of copper. The crude copper particles have a higher density than the slag and quickly descend in the foam layer and sink into the crude copper layer; the iron in the mixture forms iron-rich slag with the added quartz and limestone, and the iron of the NdFeB waste in the mixture is separated and slag-made to form rare earth slag. The rare earth slag has a higher density than the iron-rich slag, so it can be discharged separately in the middle layer between the iron-rich slag and the copper layer.

[0025] 2. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste provided by the present invention uses NdFeB waste with high iron content and electronic waste with extremely low iron content as smelting materials. On the one hand, the iron element in the NdFeB waste can be fully utilized in the smelting process to avoid additional iron addition during slag making. On the other hand, the iron element in the NdFeB waste and electronic waste in the mixed material can be used with quartz stone and limestone to slag and separate the iron in the NdFeB waste to obtain iron-rich The copper element in the mixture undergoes an oxidation-reduction reaction in the slag and is recovered, thereby effectively and simultaneously recovering the rare earth, copper, gold and silver in NdFeB waste and electronic waste, overcoming the shortcomings of the prior art that rare earth, iron and copper elements in NdFeB waste and copper, gold, silver, rare earth and other elements in electronic waste are difficult to utilize at a high value, and realizing the synchronous recovery of rare earth, copper, gold, silver and other valuable metals in NdFeB waste and electronic waste, which has huge economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic flow chart of a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste proposed by the present invention;

[0027] Figure 2 A schematic diagram of the structure of a top-blown smelting furnace used in the embodiment to recover rare earth and copper from NdFeB waste and electronic waste using the recovery method proposed by the present invention;

[0028] The reference numerals are as follows:

[0029] 1. Top-blown smelting furnace; 2. Smelting spray gun; 3. Detection rod; 4. Feeding port; 5. Slag discharge port; 6. Copper discharge port. DETAILED DESCRIPTION

[0030] In order to make the purpose, 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.

[0031] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0032] 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 other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0033] See also Figure 1As shown, the method for recovering rare earth and valuable metals from NdFeB waste and electronic waste provided by the present invention specifically comprises the following steps:

[0034] S1. Raw material pretreatment: classify, crush and sort NdFeB waste and electronic waste;

[0035] S2. Batching: pre-treated NdFeB waste and electronic waste are batched with slag-forming agent and coke, wherein the mass fraction of iron w(Fe) in the mixture obtained by batching is 23-27%, the mass fraction of silicon dioxide w(SiO2) is 35-45%, the mass fraction of calcium oxide w(CaO) is 19-25%, and the mass fraction of aluminum w(Al) is less than 5%;

[0036] S3, weak oxidation process: after the mixed material in step S2 is put into the top-blown smelting furnace 1, natural gas and process air or oxygen are introduced into the furnace through the smelting lance 2 to control the oxidizing atmosphere. The mixed material is rapidly drawn into the molten pool under the stirring of the airflow at the outlet of the lance to carry out smelting and slag-making reaction. The liquid level of the molten pool is controlled to be 1100 mm. When the liquid level reaches 1100 mm, the addition of the mixed material is stopped;

[0037] S4, foam reduction smelting: after the oxidation reaction is completed, coke is added to the oxidized slag in step S3, and process air and natural gas are continuously introduced for reduction reaction. The liquid level of the molten pool is measured by a probe rod, and the reduction endpoint and reduction time are determined based on the composition and morphology of the reduced slag at the upper part of the probe rod 3. The reduction time is 5-20 minutes;

[0038] S5. Standing and settling: When the reduction end point is reached through the detection rod 3, stop adding the reducing coke, reduce the amount of natural gas to the flow rate in the insulation state, raise the smelting lance 2 to the parking position of the smelting furnace for insulation, and stand and settle for 10-30 minutes;

[0039] S6, copper discharge and slag discharge: copper discharge operation is carried out from copper discharge port 6; slag discharge operation is carried out from slag discharge port 5, wherein rare earth slag and lean slag can be discharged separately, and after slag discharge, the ingredients are added again to start the next round of weak oxidation process slag making.

[0040] 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, the top-blown smelting furnace 1 includes a furnace body, a flue outlet and a charging port 4 are provided at the top of the furnace body, a slag discharge port 5 and a copper discharge port 6 are provided at the bottom of the furnace body, a smelting lance 2 and a detection rod 3 are provided inside the furnace body, which penetrate the inner wall of the furnace body and extend to the lower part of the furnace body, and the smelting lance 2 is used to introduce natural gas and process air into the furnace, and the detection rod 3 is used to measure the liquid level in the furnace and the reduction slag composition and morphology at the upper part of the detection rod 3 to determine the reduction end point and reduction time by analysis. In other embodiments, other smelting furnaces that can achieve the above purpose can also be selected as needed.

[0041] As an embodiment of the present invention, in step S1, the raw material can be pre-processed according to its size. If it is a large piece of slag, it needs to be broken into small pieces of 1-20 cm. If it is a powdery material, it needs to be dried and granulated to facilitate the batching and subsequent smelting process.

[0042] As an embodiment of the present invention, in step S2, the slag-forming agent is at least one of quartz stone and limestone.

[0043] As an embodiment of the present invention, in step S3, the amount of coke added during the oxidation smelting process is 0.6-0.8 t / h, and the amount of natural gas is 300-400 m 3 / h, process air volume is 6200-6500m 3 / h, the ratio of natural gas to process air volume is 1:15-1:22, and the residual oxygen concentration of flue gas is 5-10%. By controlling the conditions of the oxidation process, the rare earth, copper and iron in the mixed smelting slag are oxidized into oxides for 1.5 hours. The process can be observed and analyzed by the oxidation time or by sampling with a probe rod to ensure that the corresponding substances are fully oxidized;

[0044] As an implementation mode of the present invention, in step S3, the total amount of the mixed material entering the furnace is 2-4 t / h, the rare earth grade in the mixed material is 5-20%, and the copper grade is 3-10%.

[0045] As an embodiment of the present invention, in step S4, the amount of coke added during the reduction smelting process is 0.9-1.1 t / h, and the amount of natural gas is 500-550 m 3 / h, process air volume is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:10-1:12, and the residual oxygen concentration in flue gas is 1-4%.

[0046] By controlling the conditions of the reduction process, the copper oxide in the mixed smelting slag is reduced to metallic copper, while the iron oxide and rare earth oxide are not reduced and remain in the slag layer. The valuable metals such as gold and silver in the electronic waste are aggregated into crude copper particles rich in gold and silver under the wrapping of copper. The crude copper particles have a higher density than the slag and quickly descend into the crude copper layer in the foam layer. The iron in the NdFeB waste forms iron-rich slag with the added quartz and limestone. The rare earth slag has a higher density than the iron-rich slag, so it can be discharged separately in the middle layer between the iron-rich slag and the copper layer. In the above process, due to the high viscosity of the high-calcium and high-silicon slag, the slag is prone to produce a foam layer, which increases the surface area of ​​the slag, strengthens the gas-solid two-phase kinetic conditions, and is prone to reduction reactions.

[0047] As an embodiment of the present invention, in steps S3 and S4, the process air volume can protect the smelting lance 2 from high temperature melting, and the minimum process air volume cannot be less than 5500m 3 / h.

[0048] As an embodiment of the present invention, in step S4, when the reduction end point is reached, the slag sample on the surface of the detection rod 3 is in the shape of wire mesh mercury and the thickness of the foam layer in the molten pool is 300-1000mm. The foam layer can be quickly eliminated by controlling the ratio of insulating natural gas to process air to 1:10-1:13 and ventilating for 20 minutes.

[0049] As an embodiment of the present invention, in step S4, the reduced slag composition morphology analysis is performed by sampling with the detection rod 3, and the slag shape adjustment direction is preliminarily determined based on the physical conditions of the slag such as the thickness, color, magnetism, and weight of the detection rod 3.

[0050] As an embodiment of the present invention, in step S5, the flow rate of natural gas during the insulation process is 200-300m 3 / h, process air volume is 2000-3000m 3 / h, and the gas / air ratio is 1:10 to ensure full combustion of natural gas.

[0051] In the above technical scheme, NdFeB waste, electronic waste, quartz, limestone and coke are mixed and added to the top-blown smelting furnace. After the materials fall to the bottom of the furnace, they are stirred by the mixed airflow of the smelting spray gun and rolled into the molten pool for rapid melting. This process can make full use of the high iron content in NdFeB waste and recover the copper in electronic waste, avoiding the defect that the electronic waste needs to be supplemented with iron elements during the smelting process due to the low iron content. By controlling the conditions of the oxidation process, the rare earth, copper and iron in the mixed smelting slag are oxidized into oxides; by controlling the conditions of the reduction process, the copper oxide in the mixed smelting slag is reduced to metallic copper, and the high-valent iron oxide (ferric oxide, ferric oxide) and rare earth oxide are not reduced and remain in the slag layer. The smelting slag is reduced and smelted by controlling the slag surface height, the amount of reduced coke, the amount of natural gas, the ratio of natural gas to process air volume, the end pressure of the spray gun and the reduction time. Due to the high viscosity of high-silicon and high-calcium slag, the molten slag is prone to produce a foam layer during strong reduction smelting, which increases the surface area of ​​the slag, strengthens the gas-solid two-phase kinetic conditions, and is easy to cause reduction reactions. The valuable metals such as gold and silver in the electronic waste are aggregated into gold- and silver-rich crude copper particles under the wrapping of copper. The crude copper particles have a higher density than the slag and quickly descend in the foam layer and sink into the crude copper layer. The iron in the NdFeB waste forms iron-rich slag with the added quartz and limestone. The rare earth slag has a higher density than the iron-rich slag, so it can be discharged separately in the middle layer between the iron-rich slag and the copper layer.

[0052] The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste proposed by the present invention is further described below in conjunction with specific embodiments:

[0053] Example 1

[0054] This embodiment proposes a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste. The specific recovery method is as follows:

[0055] NdFeB waste, electronic waste, quartz, limestone and coke are mixed, and the mixed material has a slag composition of 23% iron mass fraction w(Fe), 35% silicon dioxide mass fraction w(SiO2), 19% calcium oxide mass fraction w(CaO), and 5% aluminum mass fraction w(Al); the mixed material is added into the top-blown smelting furnace 1 through the feed port 4, the molten pool liquid level is controlled to be 1100mm, the distance between the smelting lance 2 port and the liquid surface in the molten pool is 200mm, the end pressure of the lance 2 is 15kpa, the furnace temperature is 1290℃, the total amount of furnace input is 2t / h, the rare earth grade of the furnace input is 5%, the copper grade of the furnace input is 3%, the amount of coke in the oxidation process is 0.6t / h, and the amount of natural gas is controlled to be 300m 3 / h, process air volume 6200m 3 / h, the residual oxygen concentration of flue gas is 5%; the coke volume in the reduction process is 0.9t / h, and the controlled natural gas volume is 500m 3 / h, process air volume 5700m 3 / h, the residual oxygen concentration of flue gas is 4%, and the thickness of the foam layer on the slag surface of the molten pool is 350mm after 20 minutes of reduction under the reducing conditions. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 97.28% and a lean slag with a copper content of 0.45% are obtained from the copper discharge port 6 and the slag discharge port 5, respectively. The total recovery rate of rare earth in NdFeB waste is 95.3%, and the total recovery rate of copper in electronic waste is 96.6%. It should be noted that in other embodiments, the distance between the molten pool liquid level and the smelting spray gun port and the liquid surface in the molten pool can also be adjusted according to actual needs, as long as it can meet the needs of the smelting process, and this is not limited here.

[0056] Example 2

[0057] This embodiment proposes a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste. The specific recovery method is as follows:

[0058] NdFeB waste, electronic waste, quartz, limestone and coke are mixed, and the mixed material has a slag composition of 24% iron mass fraction w(Fe), 37% silicon dioxide mass fraction w(SiO2), 20% calcium oxide mass fraction w(CaO), and 4% aluminum mass fraction w(Al); the mixed material is added into the top-blown smelting furnace 1 through the feeding port 4, the molten pool liquid level is controlled to be 1100mm, the distance between the smelting lance 2 port and the liquid surface in the molten pool is 200mm, the end pressure of the lance 2 is 15kpa, the furnace temperature is 1300℃, the total amount of furnace input is 3t / h, the rare earth grade of the furnace input is 8%, the copper grade of the furnace input is 5%, the amount of coke in the oxidation process is 0.6t / h, and the amount of natural gas is controlled to be 320m 3 / h, process air volume 6200m 3 / h, the residual oxygen concentration of flue gas is 6%; the coke volume in the reduction process is 0.9t / h, and the controlled natural gas volume is 510m 3 / h, process air volume 5700m 3 / h, the residual oxygen concentration of the flue gas is 3%. After 20 minutes of reduction under the reducing conditions, the thickness of the foam layer on the slag surface of the molten pool is 400 mm. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 97.69% and a lean slag with a copper content of 0.52% were obtained from the copper discharge port 6 and the slag discharge port 5 respectively. The total recovery rate of rare earth in NdFeB waste is 96.5%, and the total recovery rate of copper in electronic waste is 96.9%.

[0059] Example 3

[0060] This embodiment proposes a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste. The specific recovery method is as follows:

[0061] NdFeB waste, electronic waste, quartz, limestone and coke are mixed, and the mixed material has a slag composition of 25% iron mass fraction w(Fe), 39% silicon dioxide mass fraction w(SiO2), 22% calcium oxide mass fraction w(CaO), and 4% aluminum mass fraction w(Al); the mixed material is added into the top-blown smelting furnace 1 through the feeding port 4, the molten pool liquid level is controlled to be 1100mm, the distance between the smelting lance 2 port and the liquid surface in the molten pool is 200mm, the end pressure of the lance 2 is 15kpa, the furnace temperature is 1320℃, the total amount of furnace input is 3t / h, the rare earth grade of the furnace input is 12%, the copper grade of the furnace input is 7%, the amount of coke in the oxidation process is 0.7t / h, and the natural gas amount is controlled to be 330m 3 / h, process air volume 6300m 3 / h, the residual oxygen concentration of flue gas is 7%; the coke volume in the reduction process is 1.0t / h, and the controlled natural gas volume is 520m 3 / h, process air volume 5800m 3 / h, the residual oxygen concentration of the flue gas is 3%. After 20 minutes of reduction under the reducing conditions, the thickness of the foam layer on the slag surface of the molten pool is 500 mm. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 97.33% and a lean slag with a copper content of 0.55% were obtained from the copper discharge port 6 and the slag discharge port 5 respectively. The total recovery rate of rare earth in NdFeB waste is 96.7%, and the total recovery rate of copper in electronic waste is 97.5%.

[0062] Example 4

[0063] This embodiment proposes a method for recovering rare earth and valuable metals from NdFeB waste and electronic waste. The specific recovery method is as follows:

[0064] NdFeB waste, electronic waste, quartz, limestone and coke are mixed, and the mixed material has a slag composition of 27% iron mass fraction w(Fe), 42% silicon dioxide mass fraction w(SiO2), 23% calcium oxide mass fraction w(CaO), and 5% aluminum mass fraction w(Al); the mixed material is added into the top-blown smelting furnace 1 through the feed port 4, the molten pool liquid level is controlled to be 1100mm, the distance between the smelting lance 2 port and the liquid surface in the molten pool is 200mm, the end pressure of the lance 2 is 15kpa, the furnace temperature is 1340℃, the total amount of furnace input is 4t / h, the rare earth grade of the furnace input is 17%, the copper grade of the furnace input is 9%, the amount of coke in the oxidation process is 0.8t / h, and the amount of natural gas is controlled to be 350m 3 / h, process air volume 6400m 3 / h, the residual oxygen concentration of flue gas is 7%; the coke volume in the reduction process is 1.1t / h, and the controlled natural gas volume is 530m 3 / h, process air volume 5800m 3 / h, the residual oxygen concentration of the flue gas is 2%. After 20 minutes of reduction under the reducing conditions, the thickness of the foam layer on the slag surface of the molten pool is 650mm. After standing and settling for 20 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 98.31% and a lean slag with a copper content of 0.43% were obtained from the copper discharge port 6 and the slag discharge port 5 respectively. The total recovery rate of rare earth in NdFeB waste is 97.4%, and the total recovery rate of copper in electronic waste is 97.9%.

[0065] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for recovering rare earth and valuable metals from NdFeB waste and electronic waste, characterized in that: The steps include: S1. Pre-treating NdFeB waste and electronic waste; S2. The pretreated NdFeB waste and electronic waste are mixed with a slag-forming agent and coke, wherein the mass fraction of iron w(Fe) in the mixed material is 23-27%, the mass fraction of silicon dioxide w(SiO2) is 35-45%, the mass fraction of calcium oxide w(CaO) is 19-25%, and the mass fraction of aluminum w(Al) is less than 5%; S3, after the mixed material in step S2 is put into a top-blown smelting furnace, natural gas and process air or oxygen are introduced to cause the mixed material to undergo oxidation smelting and slagging reaction; during the oxidation smelting process, the amount of coke added is 0.6-0.8 t / h, and the amount of natural gas is 300-400m 3 / h, process air volume is 6200-6500m 3 / h, the ratio of natural gas to process air volume is 1:15-1:22, and the residual oxygen concentration of flue gas is 5-10%; S4. After the oxidation reaction is completed, coke is added to the oxidized slag obtained in step S3, and process air and natural gas are continuously introduced for reduction reaction. The liquid level of the molten pool is measured by a probe rod, and the reduction endpoint and reduction time are determined based on the composition and morphology of the reduced slag at the upper and middle part of the probe rod. The amount of coke added during the reduction reaction is 0.9-1.1 t / h, and the amount of natural gas is 500-550m 3 / h, process air volume is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:10-1:12, and the residual oxygen concentration of flue gas is 1-4%; S5. When the reduction end point is reached by the detection rod, the addition of reducing coke is stopped, the amount of natural gas is reduced to the flow rate in the insulation state, and static sedimentation is carried out; S6. Carry out copper discharge operation from the copper discharge port; carry out slag discharge operation from the slag discharge port.

2. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S3, the total amount of the mixed material entering the furnace is 2-4 t / h, the rare earth grade in the mixed material is 5-20%, and the copper grade is 3-10%.

3. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S5, the flow rate of natural gas during the insulation process is 200-300m 3 / h, process air volume is 2000-3000m 3 / h, the ratio of natural gas to process air volume is 1:10 to ensure full combustion of natural gas.

4. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S4, when the reduction end point is reached, the slag sample on the surface of the probe rod is in the shape of wire mesh mercury and the thickness of the foam layer in the molten pool is 300-1000mm.

5. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S4, the reduction time is 5-20 minutes.

6. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 2, characterized in that: In step S3, the molten pool liquid level is controlled to be 1100 mm during the oxidation smelting process.

7. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S5, the static sedimentation time is 10-30 minutes.

8. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S2, the slag-forming agent is at least one of quartz stone and limestone.

9. The method for recovering rare earth and valuable metals from NdFeB waste and electronic waste according to claim 1, characterized in that: In step S1, the pretreatment is carried out by crushing and / or granulating.

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