A directional separation method of waste printed circuit board pyrolysis products under high-temperature water vapor atmosphere

Abstract

The application discloses a method for directional separation of valuable components in waste circuit boards under high-temperature water vapor atmosphere, which comprises pyrolysis of the waste circuit boards under high-temperature water vapor atmosphere, and directional separation of valuable metals and non-metals in the waste circuit boards by adopting eddy current separation-ball milling-magnetic separation-hydrothermal vulcanization-flotation method after crushing of the pyrolysis residue. Compared with traditional waste circuit board recycling processes, the application proposes a new method for efficient separation of pyrolysis products of the waste circuit boards under high-temperature water vapor atmosphere, which can not only separate copper and iron from other metal products, realize recycling of carbon in the pyrolysis products, but also gasify and reuse resins and other organic matters, so as to achieve the purpose of high-value recycling of all components.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for directional separation of pyrolysis products of waste circuit boards under high-temperature steam atmosphere, belonging to the field of comprehensive recycling of typical metal-inorganic solid waste, and particularly relates to directional separation and recovery of different metal valuable components in waste circuit boards. The method uses crushing-high-temperature steam pyrolysis-vortex current separation-ball milling-magnetic separation-hydrothermal sulfuration-flotation method to efficiently and directionally separate and recover valuable metals copper and iron in waste circuit boards. BACKGROUND

[0002] With the continuous development of industrialization level in China, waste circuit boards as a raw material for recycled copper have developed rapidly. Waste circuit boards have a high scrap volume, and on the one hand, they have very high resource value, and on the other hand, they have potential environmental hazards. Waste circuit boards contain a variety of heavy metals harmful to the environment, which can cause serious harm to the environment, such as Au, Ag, Pb, etc. Randomly burning or landfilling waste circuit boards can cause serious harm to the natural environment. At the same time, waste circuit boards contain bromine-containing flame retardants, which can easily produce dioxins, hydrogen bromide and other air pollutants in the combustion process, causing great harm to human health. Therefore, in view of the dual characteristics of high resource recycling value and potential pollution hazard of waste circuit boards, not only high-efficiency recycling technology should be considered in the recycling process, but also the impact on the environment should be considered. At present, the main technologies for recycling waste circuit boards include pyroprocessing, hydrometallurgical processing, and bioleaching, all of which have obvious shortcomings, such as secondary air pollution caused by pyroprocessing, environmental pollution caused by waste liquid in hydrometallurgical processing, and long cycle period of bioleaching technology.

[0003] For the recycling process of waste circuit boards, pyrolysis has obvious advantages such as high resource recovery rate and high-value reuse of different valuable components. At present, pyrolysis for treating waste circuit boards has not been widely used in industrial applications. The main reason is that the phenolic resin or epoxy resin in waste circuit boards produces fine carbon particles in the pyrolysis process, which is difficult to separate from metals, and the non-metallic materials in the pyrolysis products are difficult to separate from the metallic materials, direct calcination leads to oxidation of metals and the heat value of fine carbon particles cannot be reused. SUMMARY

[0004] The application provides a method for directional separation of waste circuit board pyrolysis products under high-temperature water vapor atmosphere, and belongs to the field of comprehensive recycling of typical metal-inorganic solid waste. In particular, the method relates to efficient directional separation and high-value recycling of different metal valuable components in waste circuit boards and non-metallic mineral components, fully utilizes pyrolysis gas and pyrolysis oil, and the pyrolysis residue mainly contains a mixture of copper, iron, lead, tin, gold and other metals and non-metallic glass fibers. Under the condition of high-temperature water vapor, the carbon in the pyrolysis products is converted into carbon monoxide and hydrogen, the pyrolysis gas is reused to the waste circuit board pyrolysis stage, and the heat generated in the steel belt pyrolysis furnace pyrolysis process can be reused to the hydrothermal sulfidation stage and the spray tower spraying stage. The pyrolysis residue is crushed by using a roller-type ball mill to reduce the particle size, and the crushed pyrolysis residue is separated by using an eddy current separator to obtain a metal concentrate 1 (copper, iron, lead, tin, etc.) and a non-metallic concentrate 1 (fine particle resin powder). The metal concentrate 1 is finely ground by using a horizontal ball mill, and the particle size is reduced to obtain a metal concentrate 2. The metal concentrate 2 is magnetically separated by using a roller-type magnetic separator to obtain metallic iron and a metal concentrate 3. The metal concentrate 3 is hydrothermally sulfidized by adding a sulfidation promoter MBT, and metallic copper and a metal concentrate 4 (lead, tin, gold, etc.) are obtained by adding an adjusting agent water glass, a collector Z200 and a frother No. 2 oil floatation. Through the above pyrolysis process and the directional separation process of the valuable components of the waste circuit board metals and non-metals, various valuable components can be recycled and utilized, the pyrolysis product carbon can be gasified and reused, the metallic copper and iron can be separated, and the directional separation efficiency of the valuable components is greatly improved.

[0005] The raw materials used in the above scheme include: a leaching solution NaOH, a sulfidation promoter MBT (2-mercaptobenzothiazole), a frother No. 2 oil, an adjusting agent water glass, and a collector Z200 (ethyl thiuram sulfide).

[0006] The application provides a method for directional separation of waste circuit board pyrolysis products under high-temperature water vapor atmosphere, and the method comprises the following steps:

[0007] (1) Waste circuit board pyrolysis under high-temperature water vapor: the waste circuit board is pyrolyzed by using a continuous feeding type steel belt pyrolysis furnace, high-temperature water vapor is introduced into the pyrolysis furnace by using a high-temperature water vapor generator, N2 is introduced into the pyrolysis furnace to maintain an oxygen-free environment, the generated pyrolysis furnace flue gas is sent into a boiler for cooling and recycling the heat in the pyrolysis flue gas, and the pyrolysis oil gas mixture and the pyrolysis residue are obtained in the pyrolysis process.

[0008] Preferably, the initial temperature of the continuous steel belt pyrolysis furnace is 150-300 DEG C, the end temperature is 750-900 DEG C, and the pyrolysis time is 120-180 min. Three-stage partition temperature heating is adopted, one partition temperature is 150-300 DEG C, two partition temperature is 300-750 DEG C, and three partition temperature is 750-900 DEG C. In the application, the pyrolysis temperature of the circuit board is 150-900 DEG C, and the partition heating can make the pyrolysis effect better. Compared with the pyrolysis scheme without water vapor, the three-stage partition temperature is increased after the high-temperature water vapor is introduced, and the water vapor and the pyrolysis product carbon react to generate carbon monoxide and hydrogen under high-temperature conditions. Preferably, the high-temperature water vapor temperature is 200 DEG C, and the carbon gasification rate is 92%-98%.

[0009] The pyrolysis residue is mainly composed of a mixture of copper, iron, lead and other metals and a mixture of non-metals such as glass fibers. The main components of the pyrolysis gas include lower aliphatic hydrocarbons, low molecular weight aromatic hydrocarbons, hydrogen bromide, carbon monoxide, carbon dioxide and the like. The main components of the pyrolysis oil include phenol, 4-isopropyl phenol, 2-isopropyl phenol and other phenolic substances.

[0010] (2) Alkaline liquor spraying separates the oil-gas mixture: the oil-gas mixture generated after pyrolysis is sent to an alkaline liquor spraying tower for condensation, the hydrogen bromide in the oil-gas mixture is absorbed by the alkaline liquor to generate bromide salt, and the pyrolysis oil and the pyrolysis gas are separated at the same time;

[0011] Preferably, the alkaline liquor used is NaOH solution, and the mass concentration is 5%-10%.

[0012] During the alkaline liquor spraying process, the acidic gas (such as HBr) in the oil-gas mixture is absorbed by the NaOH solution to generate NaBr, the NaBr solution is evaporated dry by the heat of the flue gas boiler, NaBr is obtained, and the pyrolysis oil and the pyrolysis gas are separated at the same time.

[0013] (3) Pyrolysis residue crushing and eddy current separation: a drum-type ball mill is used to crush the pyrolysis residue, and the crushing product is separated by an eddy current separator to obtain a metal concentrate 1 and a non-metal concentrate 1;

[0014] Preferably, the particle size of the crushing product is 3-80 mm, the width of the eddy current separator is 400-800 mm, and the driving power is 3.7-5.5 kw. The main components of the metal concentrate 1 are copper, iron, lead, gold and other elements, and the non-metal concentrate 1 contains SiO2 and other non-metals.

[0015] (4) Fine grinding and magnetic separation of pyrolysis residue: a horizontal ball mill is used to finely grind the metal concentrate 1 to reduce the particle size, and a metal concentrate 2 is obtained; a drum-type magnetic separator is used to magnetically separate the metal concentrate 2, and metal Fe and a metal concentrate 3 are obtained after magnetic separation;

[0016] Preferably, the particle size of the metal enrichment body 2 is 0.03-1mm; the length of the drum diameter of the drum magnetic separator is 600-1200mm, the length of the drum is 1200-2400mm; the motor power of the magnetic separator is 2.2-5.5kw. After the iron is separated by magnetic separation, the metal enrichment body 3 mainly contains Cu, Pb, Pd and other metals, and the recovery rate of iron is 98%-99.5%.

[0017] (5) Hydrothermal sulfidation and copper flotation: hydrothermal sulfidation is carried out on the metal enrichment body 3 by adding a sulfidation promoter, and copper is recovered by flotation by adding an adjusting agent, a collector and a foaming agent.

[0018] Preferably, the pulp concentration of the metal enrichment body 3 is 25%-35%.

[0019] Preferably, the sulfidation promoter is MBT, the adjusting agent is water glass, the collector is Z200, and the foaming agent is No. 2 oil.

[0020] Preferably, the concentration of the sulfidation promoter MBT is 50-150g / t, the concentration of the adjusting agent water glass is 50-200g / t, the concentration of the collector Z200 is 80-240g / t, the concentration of the foaming agent No. 2 oil is 20-80g / t, and the recovery rate of copper is 88%-94%.

[0021] The present application has the following beneficial effects:

[0022] The application discloses a method for directional separation of valuable components of waste circuit boards under a high-temperature water vapor atmosphere, which comprises pyrolyzing the waste circuit boards under the high-temperature water vapor atmosphere, and then adopting the eddy current separation-ball milling-magnetic separation-hydrothermal sulfidation-flotation method to directionally separate valuable metals and nonmetals in the waste circuit boards after crushing the pyrolysis residue.

[0023] Specifically, by adding high-temperature water vapor in the pyrolysis process, high-molecular organic matters such as epoxy resin or phenolic resin are converted into an oil-gas mixture under oxygen-free conditions. The oil-gas mixture is condensed by a sodium hydroxide solution and then enters a spray tower to produce sodium bromide. The solid carbon produced by pyrolysis is converted into carbon monoxide, and the high-temperature water vapor reacts with bromine in the circuit board to generate hydrogen bromide, achieving the purpose of removing bromine flame retardant. The pyrolysis residue produced in the pyrolysis process is crushed and sorted by eddy current to separate metal concentrate 1 and non-metal concentrate 1. After ball milling, the metal concentrate 1 is subjected to magnetic separation to separate the metal iron from other metal concentrates. The remaining metal concentrate is subjected to hydrothermal sulfidation, and adjusting agent, activator, collector and foaming agent are added to float copper. At the same time, the heat generated by the pyrolysis system provides continuous energy for the system, and the heat is reused in the oil-gas mixture spraying stage and the hydrothermal sulfidation stage.

[0024] Through the above pyrolysis and separation process, efficient and directional separation and enrichment of waste circuit board pyrolysis products are realized, and high-value recycling of various components is realized. Therefore, the present application plays a promoting role in high-value recycling of various components of waste circuit boards, and is a technology with high recovery rate, small environmental pollution and high utilization rate of pyrolysis products, which has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 Flow chart of the present application for directional separation of waste circuit board pyrolysis products under high-temperature water vapor atmosphere. DETAILED DESCRIPTION

[0027] The same batch of waste circuit boards (computer motherboards) is used in the embodiment. According to element analysis, the mass percentages of Cu, C, H and Br are 31.32%, 20.82%, 2.18% and 4.78%, respectively. According to industrial analysis results, the mass percentages of ash, volatile matter, moisture and fixed carbon are 64.28%, 25.23%, 0.06% and 10.43%, respectively. The specific implementation is as follows:

[0028] Embodiment 1

[0029] The waste printed circuit board is treated by using a continuous steel belt pyrolysis furnace, high-temperature water vapor of 200°C is introduced into the pyrolysis furnace through a water vapor generator, N2 is introduced to maintain an oxygen-free environment, the initial temperature is set to 200°C and the end temperature is set to 800°C. Three-stage partition temperature heating is adopted, the first partition temperature is 200°C, the second partition temperature is 650°C, and the third partition temperature is 800°C, the pyrolysis time is 150 min, the carbon gasification rate is 96.4%, and the pyrolysis residue and oil gas mixture are obtained after pyrolysis;

[0030] The oil gas mixture is introduced into a condensation spray tower, a sodium hydroxide solution with a mass concentration of 5% is used, and after spraying, the pyrolysis oil and pyrolysis gas are separated and sodium bromide solution is produced, which is evaporated dry by the heat generated by the flue gas boiler;

[0031] A drum-type ball mill is used to crush the pyrolysis residue, the particle size range of the crushed particles is 5mm-60mm, a vortex current separator is used to separate the crushed pyrolysis residue, the separator belt width is 600mm, and the driving power is 4.2kw, to obtain metal concentrate 1 and non-metal concentrate 1; a horizontal ball mill is used for fine grinding of the metal concentrate 1, the discharge particle size range (metal concentrate 2) is 0.05mm-1mm, a drum-type magnetic separator is used for magnetic separation of the metal concentrate 2, the drum diameter length is 800mm, the drum length length is 1600mm, and the magnetic separator motor power is 3.2kw, to obtain metal Fe and metal concentrate 3 containing Cu, Pb, Pd and other metals after magnetic separation, and the iron recovery rate is 98%;

[0032] The pulp concentration of the metal concentrate 3 is 30%, sulfidation flotation is carried out, the concentration of sulfidation promoter MBT is 100g / t, the regulator water glass concentration is 100g / t, the collector Z200 concentration is 160g / t, the foaming agent No.2 oil concentration is 40g / t, and the copper recovery rate is 91.8%.

[0033] Example 2

[0034] The waste printed circuit board is treated by using a continuous steel belt pyrolysis furnace, high-temperature water vapor of 200°C is introduced into the pyrolysis furnace through a water vapor generator, N2 is introduced to maintain an oxygen-free environment, the initial temperature is set to 150°C and the end temperature is set to 750°C. Three-stage partition temperature heating is adopted, the first partition temperature is 150°C, the second partition temperature is 350°C, and the third partition temperature is 750°C, the pyrolysis time is 120 min, the carbon gasification rate is 92%, and the pyrolysis residue and oil gas mixture are obtained after pyrolysis;

[0035] The oil gas mixture is introduced into a condensation spray tower, a sodium hydroxide solution with a mass concentration of 8% is used, and after spraying, the pyrolysis oil and pyrolysis gas are separated and sodium bromide solution is produced, which is evaporated dry by the heat generated by the flue gas boiler;

[0036] The pyrolysis residue is crushed by a drum-type ball mill, the particle size of the crushed product is 3mm-50mm, the crushed pyrolysis residue is separated by an eddy current separator, the belt width of the separator is 400mm, the driving power is 3.7kw, and metal concentrate 1 and non-metal concentrate 1 are obtained; the metal concentrate 1 is finely ground by a horizontal ball mill, the particle size range of the discharged product (metal concentrate 2) is 0.03mm-0.8mm, the metal concentrate 2 is separated by a drum-type magnetic separator, the drum diameter is 600mm, the drum length is 1200mm, the motor power of the magnetic separator is 2.2kw, and after the magnetic separation, metal Fe and metal concentrate 3 containing Cu, Pb, Pd and other metals are obtained, and the recovery rate of Fe is 98.2%;

[0037] The pulp concentration of the metal concentrate 3 is 30%, the sulfidation flotation is carried out, the concentration of the sulfidation promoter MBT is 100g / t, the regulator water glass concentration is 80g / t, the collector Z200 concentration is 120g / t, the foaming agent No.2 oil concentration is 60g / t, and the recovery rate of Cu is 90.2%.

[0038] Example 3

[0039] The waste circuit board is treated by a continuous steel belt pyrolysis furnace, 200℃ high-temperature water vapor is introduced into the pyrolysis furnace by a water vapor generator, N2 is introduced to maintain an oxygen-free environment, the initial pyrolysis temperature is set to 300℃ and the end temperature is set to 900℃. Three-stage partition temperature control heating is adopted, the first partition temperature is 300℃, the second partition temperature is 500℃, and the third partition temperature is 900℃, the pyrolysis time is 180min, the gasification rate of carbon is 98%, and a pyrolysis residue and oil gas mixture are obtained after pyrolysis;

[0040] The oil gas mixture is introduced into a condensation spray tower, a sodium hydroxide solution with a mass concentration of 10% is used for spraying, and after the spraying, the pyrolysis oil and pyrolysis gas are separated and sodium bromide solution is produced, the sodium bromide solution is evaporated by the heat generated by the flue gas boiler;

[0041] The pyrolysis residue is crushed by a drum-type ball mill, the particle size of the crushed product is 8mm-80mm, the crushed pyrolysis residue is separated by an eddy current separator, the belt width of the separator is 800mm, the driving power is 5.5kw, and metal concentrate 1 and non-metal concentrate 1 are obtained; the metal concentrate 1 is finely ground by a horizontal ball mill, the particle size range of the discharged product (metal concentrate 2) is 0.05mm-1mm, the metal concentrate 2 is separated by a drum-type magnetic separator, the drum diameter is 1200mm, the drum length is 2400mm, the motor power of the magnetic separator is 5.5kw, and after the magnetic separation, metal Fe and metal concentrate 3 containing Cu, Pb, Pd and other metals are obtained, and the recovery rate of Fe is 99.5%;

[0042] The pulp concentration of the metal concentrate 3 is 35%, and sulfidation flotation is performed thereon, and the concentration of the sulfidation promoter MBT added is 150 g / t. The regulator water glass concentration is 100 g / t, the collector Z200 concentration is 240 g / t, the frother No. 2 oil concentration is 80 g / t, and the copper recovery rate is 94%.

[0043] Example 4

[0044] The waste circuit board is treated by using a continuous steel belt pyrolysis furnace, 200℃ high-temperature water vapor is introduced into the pyrolysis furnace through a water vapor generator, N2 is introduced to maintain an oxygen-free environment, the initial pyrolysis temperature is set to 200℃ and the end temperature is set to 800℃. Three-stage partition temperature control heating is adopted, the first partition temperature is 200℃, the second partition temperature is 450℃, and the third partition temperature is 800℃, the pyrolysis time is 140 min, the carbon gasification rate is 94.8%, and the pyrolysis residue and oil gas mixture are obtained after pyrolysis;

[0045] The oil gas mixture is introduced into a condensation spray tower, and a sodium hydroxide solution with a mass concentration of 10% is used for spraying. After spraying, the pyrolysis oil and pyrolysis gas are separated and sodium bromide solution is produced, and the sodium bromide solution is evaporated by the heat generated by the flue gas boiler;

[0046] The pyrolysis residue is crushed by using a drum-type ball mill, and the particle size range is 5mm-60mm. The crushed pyrolysis residue is separated by using an eddy current separator, the separator belt width is 500mm, and the driving power is 4.4kw. Metal concentrate 1 and non-metal concentrate 1 are obtained. The metal concentrate 1 is finely ground by using a horizontal ball mill, and the discharge particle size range (metal concentrate 2) is 0.1mm-1mm. The metal concentrate 2 is magnetically separated by using a drum-type magnetic separator, the barrel diameter length is 800mm, the barrel length length is 2000mm, and the magnetic separator motor power is 4.2kw. After magnetic separation, metal Fe and metal concentrate 3 containing Cu, Pb, Pd and other metals are obtained, and the iron recovery rate is 99%;

[0047] The pulp concentration of the metal concentrate 3 is 25%, and sulfidation flotation is performed thereon, and the concentration of the sulfidation promoter MBT added is 50 g / t. The regulator water glass concentration is 50 g / t, the collector Z200 concentration is 80 g / t, the frother No. 2 oil concentration is 20 g / t, and the copper recovery rate is 88%.

[0048] Comparative Example 1

[0049] Comparative Example 1 and Example 1 have basically the same process steps, except that three-stage partition temperature control heating is not used in step 1). The heating method is as follows: the temperature in the pyrolysis furnace is maintained at 750℃, the pyrolysis time is 120 min, and the oil gas mixture and pyrolysis residue are obtained after pyrolysis;

[0050] The carbon gasification rate is 60.8%;

[0051] The recovery rate of copper was 85.2%.

[0052] Compared with Example 1, the carbon gasification rate of Comparative Example 1 decreased obviously due to the absence of three-stage partition temperature control heating. The recovery rate of copper decreased. The main reason was that the carbon particles after pyrolysis were small in size and the carbon gasification rate was low, so that the carbon and metal could not be separated, which affected the recovery of copper.

[0053] Comparative Example 2

[0054] Comparative Example 2 was basically the same as Example 1 in process steps, except that the temperature of three-stage partition temperature control heating in step 1) was different. The specific parameters were as follows: the temperature of the first partition was 180℃, the temperature of the second partition was 400℃, the temperature of the third partition was 520℃, and the pyrolysis time was 150 min. An oil-gas mixture and a pyrolysis residue were obtained after pyrolysis.

[0055] The carbon gasification rate was 42.6%.

[0056] The recovery rate of copper was 83.6%.

[0057] Compared with Example 1, the carbon gasification rate in Comparative Example 2 was low due to the low temperature of three-stage partition heating. The main reason was that the reaction of carbon and steam was not complete at low temperature, which could not generate carbon monoxide and hydrogen. At the same time, the recovery rate of copper decreased, mainly because the fine carbon particles affected the flotation process.

[0058] Comparative Example 3

[0059] Comparative Example 3 was basically the same as Example 1 in process steps, except that the setting parameters of the eddy current separator in step 3) were different. The specific parameters were as follows: the width of the eddy current separator was 1000 mm, and the driving power was 1.0 kw.

[0060] The recovery rate of copper was 72.4%.

[0061] Compared with Example 1, the separation of metal particles and non-metal particles was not complete due to the change of the setting parameters of the eddy current separator, and a part of the metal was enriched in the non-metal, which led to a significant decrease in the recovery rate of copper in Comparative Example 3.

[0062] Comparative Example 4

[0063] Comparative Example 4 was basically the same as Example 1 in process steps, except that the setting parameters of the magnetic separator in step 4) were different. The specific parameters were as follows: the length of the drum-type magnetic separator was 600 mm, the length of the cylinder was 800 mm, and the motor power of the magnetic separator was 1.2 kw.

[0064] The recovery rate of iron was 78.4%.

[0065] Compared with example 1, the metallic iron cannot be completely separated from other metals due to the change of the parameters of the drum magnetic separator, and the recovery rate thereof is obviously decreased.

[0066] Comparative example 5

[0067] Comparative example 5 is basically the same as the process steps of example 1, except that no vulcanizing agent MBT and collector Z200 are added in step 5), and the specific parameters are as follows: the water glass concentration is 100 g / t, and the foaming agent No. 2 oil concentration is 40 g / t.

[0068] The recovery rate of copper is 50.5%.

[0069] Compared with example 1, the recovery rate of copper in comparative example 5 is obviously decreased due to the absence of vulcanizing agent and collector.

[0070] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be determined by the protection scope of the claims.

Claims

1. A method for directional separation of pyrolysis products from waste circuit boards under a high-temperature steam atmosphere, characterized in that, Includes the following steps: (1) Pyrolysis of waste circuit boards under high temperature steam: Waste circuit boards are pyrolyzed through a continuous feed steel strip pyrolysis furnace. High temperature steam is introduced into the pyrolysis furnace through a high temperature steam generator. N2 is introduced into the pyrolysis furnace to maintain an oxygen-free environment. The generated pyrolysis furnace flue gas is sent to the boiler for cooling and the heat in the pyrolysis flue gas is recovered. At the same time, the pyrolysis process yields a pyrolysis oil-gas mixture and pyrolysis residue. In step (1), the initial temperature of the continuous steel strip pyrolysis furnace is 150~300℃, the final temperature is 750~900℃, the pyrolysis time is 120min~180min, and the gasification rate of the char is 92%~98%. The pyrolysis adopts a three-stage zoned temperature control heating method: zone one temperature is 150~300℃, zone two temperature is 300~750℃, and zone three temperature is 750~900℃. (2) Alkali spray separation of oil-gas mixture: The oil-gas mixture generated after pyrolysis is sent to the alkaline spray tower for condensation. The hydrogen bromide in the oil-gas mixture is absorbed by the alkaline solution to generate bromide salt, and at the same time, the pyrolysis oil and pyrolysis gas are separated. (3) Pyrolysis slag crushing and eddy current separation: The pyrolysis slag is crushed by a drum ball mill, and the crushed products are separated by an eddy current separator to obtain metal-rich mass 1 and non-metal-rich mass 1. In step (3), the particle size of the crushed product is 3~80mm, the bandwidth of the eddy current separator is 400~800mm, and the driving power is 3.7~5.5kw; (4) Fine grinding and magnetic separation of pyrolysis residue: The metal enrichment 1 is finely ground using a horizontal ball mill to reduce the particle size and obtain metal enrichment 2; the metal enrichment 2 is magnetically separated using a drum magnetic separator to obtain metal Fe and metal enrichment 3. In step (4), the particle size of the metal enrichment 2 is 0.03~1mm; the diameter of the drum magnetic separator is 600~1200mm and the length is 1200~2400mm; the motor power of the drum magnetic separator is 2.2~5.5kw, and the iron recovery rate is 98%~99.5%; (5) Hydrothermal sulfidation and copper flotation: Add a sulfidation promoter to the metal-rich aggregate 3 for hydrothermal sulfidation, and add a modifier, collector and frother for flotation to recover copper.

2. The method according to claim 1, characterized in that, In step (2), the alkaline solution used is NaOH solution with a mass concentration of 5% to 10%.

3. The method according to claim 1, characterized in that, In step (5), the slurry concentration of the metal-rich aggregate 3 is 25%~35%.

4. The method according to claim 1, characterized in that, In step (5), the vulcanization accelerator is MBT, the modifier is water glass, the collector is Z200, and the foaming agent is No. 2 oil.

5. The method according to claim 4, characterized in that, The concentration range of the sulfidation accelerator MBT is 50~150g / t, the concentration range of the modifier water glass is 50~200g / t, the concentration range of the collector Z200 is 80~240g / t, the concentration range of the foaming agent No. 2 oil is 20~80g / t, and the copper recovery rate is 88%~94%.

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