An efficient and environmentally friendly recycling system for valuable metals from waste circuit boards

Abstract

The present invention discloses an efficient and environmentally friendly recovery system for valuable metals from waste circuit boards. The environmental protection recovery system includes a waste circuit board disassembly and crushing device, a waste circuit board and copper concentrate mixed smelting device, and a smelting flue gas purification and recovery device. When using the recovery system of the present invention for recovery, first, the waste circuit boards are desnidered, crushed, copper wires removed, iron removed, and aluminum removed. The copper-containing waste circuit boards are extruded into small pieces of materials and mixed with copper concentrate in proportion, and then added to a large-volume smelting furnace, and smelted by spraying with an ultra-rich oxygen spray gun, so that the organic components in the waste circuit boards burn more thoroughly, avoiding the generation of harmful substances. At the same time, the flue gas temperature is higher, and the waste heat boiler can effectively recover the heat generated by the waste circuit boards. The combustion flue gas is recovered through the flue gas purification and recovery device, effectively solving the impact of waste circuit board combustion on sulfuric acid production from flue gas; the recovery system of the present invention is scientifically and reasonably designed and can be widely promoted and used.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly to an efficient and environmentally friendly recycling system for valuable metals from waste circuit boards. Background Art

[0002] Since the 20th century, with the rapid development of the electronic information industry, the amount of electronic waste generated has been increasing at a rate of 10 - 15% per year. China is the largest consumer of electronic products, and the amount of electronic products discarded due to replacement each year is not less than 7 million tons. Waste circuit boards are different from domestic waste. They usually contain 30% plastic, 30% inert oxides, and 40% valuable metals. The valuable metals mainly include 20% copper, 8% iron, 2% nickel, 4% tin, 2% zinc, etc., accounting for about 39% of the waste; precious metals include gold, silver, palladium, etc. The precious metals in waste circuit boards have always been a major driving force for the development of the circuit board recycling industry, and ordinary metals also have high recycling value due to their large usage. Therefore, it is of great significance to comprehensively recycle waste circuit boards cleanly and efficiently.

[0003] During 2016 - 2018, the applicant took the method of mixing waste circuit boards with copper concentrate in a certain proportion after desniffing and crushing, and adding them to a copper refining furnace for refining together to recover the main precious metals. This method solved some problems in waste circuit board recycling: through mixed incineration, precious metals such as copper, gold, and silver in the waste circuit boards were transferred to the copper water and recovered by electrolytic refining of copper, and other rare precious metals were recovered through copper anode slime. Moreover, through closed high-temperature incineration, the amount of toxic and harmful gases generated by ordinary incineration of waste circuit boards was greatly reduced. However, in the actual production process, it was found that there were many deficiencies in directly using the desniffed and crushed circuit boards as raw materials for copper concentrate: 1. The desniffing flue gas in the raw material treatment process was not centrally treated, and it was a serious pollutant; 2. The copper wires in the raw materials would block various feeding hoppers, resulting in the suspension of production; 3. The circuit boards contained a large amount of iron, which affected smelting slag formation; 4. The circuit boards contained a large amount of aluminum, and there were problems such as being unable to melt or requiring a large amount of heat for melting; 5. The feeding amount of crushed circuit boards per hour had to be controlled below 2% of the total feeding amount. Exceeding this ratio would lead to abnormal production and low processing efficiency; 6. The waste circuit boards were prone to crusting after melting, reducing the fluidity of the slag; 7. The content of organic impurities in the flue gas generated by burning circuit boards was relatively high, and direct emission caused serious pollution; 8. The fluorine and chlorine in the flue gas generated by burning circuit boards were relatively high. Using this flue gas directly as the flue gas for producing sulfuric acid would result in poor-quality sulfuric acid, which could not form a commercial product or be directly used in other processes; 9. A large amount of coke was easily formed and blocked the flue in the flue duct, affecting normal production.

[0004] For the above reasons, the existing process methods and process equipment for mixing and smelting waste circuit boards and copper concentrates in a certain proportion cannot be actually applied in industrial production. Therefore, it is of great significance to improve the existing process equipment and process methods so that waste circuit boards can directly participate in the mixing and smelting process with copper concentrates and environmentally friendly recycle the valuable metals in waste circuit boards directly. Summary of the Invention

[0005] The object of the present invention is to provide a high-efficiency and environmentally friendly recovery system for valuable metals in waste circuit boards aiming at the above problems existing in the mixing and smelting of existing waste circuit boards and copper concentrates, which lead to the inability of the existing process equipment and methods to be actually applied in industrial production.

[0006] The technical solution of the present invention is: a high-efficiency and environmentally friendly recovery system for valuable metals in waste circuit boards, including a waste circuit board disassembly and crushing device, a mixing and smelting device for waste circuit boards and copper concentrates, and a smelting flue gas purification and recovery device;

[0007] The waste circuit board disassembly and crushing device has a waste circuit board storage bin. After the waste circuit board storage bin, a desoldering machine, a crusher, a hook separator, a magnetic separator, a screening machine, and an eddy current sorter are successively arranged. An electric bin valve is provided at the bottom of the waste circuit board storage bin. The discharge port of the electric bin valve is provided with a first belt conveyor, which conveys the material to the feed port of the desoldering machine. The desoldering machine is internally provided with a rolling screen and is connected with a hot air supply pipe to melt and roll off the tin liquid on the material in the desoldering machine. A tin liquid receiving tray is provided at the bottom of the desoldering machine. The discharge port of the desoldering machine is provided with a second belt conveyor, which conveys the processed material in the desoldering machine to the feed port of the crusher. The crushed material is conveyed from the discharge port of the crusher to the hook separator to hook out the copper wires in the material. A copper wire collecting hopper is provided below the hook separator. The discharge port of the hook separator is provided with a third belt conveyor, which conveys the material to the screening machine. The magnetic separator is located above the third belt conveyor, and an iron-containing material collecting hopper is provided at the discharge port of the magnetic separator. After the screening machine screens the material into three specifications of large, medium, and small according to the material size, according to different current settings, it enters the corresponding eddy current sorters respectively. The eddy current sorters sort the aluminum blocks and copper blocks in the material, and respectively fall through the aluminum block discharge port and the copper block discharge port onto their respective conveyor belts and are conveyed to the aluminum-containing material collecting hopper and the copper-containing material collecting hopper;

[0008] The material collected by the copper-containing material collecting hopper is conveyed to a waste circuit board extruder, extruded into block materials with a size of 3 - 5 cm, and then mixed with copper concentrates and other fluxing auxiliary materials in a certain proportion and enters the mixing and smelting device for waste circuit boards and copper concentrates;

[0009] The waste circuit board and copper concentrate mixed smelting device has a large-volume smelting furnace, which is used to receive waste circuit boards, copper concentrate and other fluxing auxiliary materials for smelting. The lower part of the smelting furnace of the large-volume smelting furnace is a furnace with a diameter of φ5m and a height of 19m, and the upper part is a frustum-shaped secondary flue gas combustion chamber with a diameter gradually decreasing from 3m to 0.5m and a height of 34.7m. An ultra-rich oxygen spray gun is inserted into the large-volume smelting furnace from the furnace mouth, and a spray gun tuyere and a sleeve tuyere are provided on the spray gun, which increases the residence time of the flue gas in the secondary flue gas combustion chamber; a melt outlet is provided at the lower part of the smelting furnace of the large-volume smelting furnace, and an electric furnace, a converter and a refining furnace are connected in series after the liquid outlet in sequence, and the melt discharged from the smelting furnace is subjected to electric furnace sedimentation, converter smelting and refining furnace refining in sequence to extract copper and other valuable metals; a flue is connected to the upper part of the secondary flue gas combustion chamber to transport the flue gas to a waste heat recovery boiler to recover heat, and the flue gas coming out of the waste heat recovery boiler is input into a smelting flue gas purification and recovery device;

[0010] The smelting flue gas purification and recovery device is located behind the waste heat recovery boiler. It includes a flue gas electrostatic precipitator, a flue gas purification tower, a sulfur dioxide converter, a sulfuric acid absorption tower and a tail gas absorption tower connected in series in sequence. The flue gas coming out of the waste heat recovery boiler is purified twice by the flue gas electrostatic precipitator and the flue gas purification tower, and then enters the sulfur dioxide converter to be converted into sulfur trioxide, and then is absorbed by the sulfuric acid absorption tower to make concentrated sulfuric acid; a flue gas inlet is provided at the bottom of the flue gas purification tower, and a concentrated sulfuric acid spraying device and a flue gas outlet are provided at the top; in the tail gas absorption tower, hydrogen peroxide is sprayed to absorb the remaining sulfur trioxide and sulfur dioxide in the flue gas and then discharged;

[0011] Valves, pumps or fans are installed on the connecting pipes between the above devices as required.

[0012] Dust collection pipes are provided above the waste circuit board storage bin, desoldering machine, crusher, hook separator and screening machine. After collecting the dust generated during the operation of each device, it is introduced into a pulse dust collector for dust removal treatment.

[0013] The ultra-rich oxygen spray gun is composed of four concentric steel cylinders. Pulverized coal, oxygen, spray gun air and sleeve air are introduced into the four concentric steel cylinders from the inside to the outside in sequence, and the air inlets of oxygen, spray gun air and sleeve air are opened on the side walls of the concentric steel cylinders in sequence.

[0014] A concentrated sulfuric acid purification device is also provided on one side of the flue gas purification tower. The concentrated sulfuric acid purification device has a cylindrical shell, a liquid inlet is provided at the lower part, a liquid outlet is provided at the upper part, a sewage outlet is provided at the bottom, and an exhaust outlet is provided at the top. Inside the cylindrical shell, three conical filter plates made of polymer materials are installed from bottom to top in sequence. The pore diameters of the three polymer filter plates decrease from bottom to top in sequence. The contaminated concentrated sulfuric acid liquid enters from the lower liquid inlet and then passes through the three filter plates in sequence and is discharged through the liquid outlet, and is circulated and pumped into the concentrated sulfuric acid spraying device at the top of the flue gas purification tower.

[0015] A number of vibrators are also installed on the outer wall of the flue.

[0016] The working process of the present invention is as follows: First, the waste circuit boards are broken and disassembled by a waste circuit board disassembling and crushing device. Specifically, the waste circuit boards are conveyed into a desoldering machine, and hot air is used to heat the waste circuit boards to melt the tin on the waste circuit boards. The tin liquid is thrown out by the rolling of the waste circuit boards in a rolling screen, and the tin liquid is recovered from the bottom tin receiving tray. Then, the desoldered waste circuit boards are crushed. The crushed materials are generally copper wires, iron blocks, aluminum blocks of different sizes, and copper-containing scraps. After crushing, a large amount of copper wires in the materials are first selected by picking, and then the iron-containing materials in the materials are selected by a magnetic separator to recover the valuable metal iron. The materials after iron removal are screened into three specifications of large, medium, and small sizes through three-stage screening, and are respectively fed into three eddy current separators with different current magnitudes. The copper and aluminum generate different magnetisms through eddy currents, and the aluminum blocks in the materials are selected to recover the valuable metal aluminum. Then, the remaining copper-containing materials are collected to recover the valuable metal copper;

[0017] Then, the copper-containing waste circuit boards are concentrated and fed into a waste circuit board extruder to be extruded into block materials with a size of 3 - 5 cm, and then fed into a waste circuit board and copper concentrate mixed smelting device. Specifically, the extruded block waste circuit boards, copper concentrate, and other fluxing auxiliary materials are mixed in a certain proportion and then put into a smelting furnace. Super-oxygen-enriched spray guns are used for spray smelting, so that the waste circuit boards in the furnace burn fully with the smelting of the copper concentrate. After the flue gas generated by combustion is further fully burned in the flue gas secondary combustion chamber, it enters a waste heat recovery boiler for heat recovery; after the melt in the smelting furnace is discharged from the liquid outlet at the lower part of the smelting furnace, it is subjected to electric furnace sedimentation, converter smelting, and refining furnace refining to extract copper and other valuable metals in turn;

[0018] The flue gas coming out of the waste heat recovery boiler passes through a flue gas electrostatic precipitator, a flue gas purification tower, a sulfur dioxide converter, a sulfuric acid absorption tower, and a tail gas absorption tower in turn for environmental protection and acid production by recycling.

[0019] In the above process, the present invention mainly solves the following problems:

[0020] 1. The unreasonable splitting of raw materials leads to problems such as copper wires clogging the feeding hopper during the mixed smelting of waste circuit boards and copper concentrate, the density of waste circuit boards being too small, making them easy to float on the surface of the melt and unable to burn fully, and the excessive content of metals such as iron and aluminum in waste circuit boards, resulting in inability to smelt or the need to increase heat for melting;

[0021] 2. The problem that the waste circuit boards are prone to crusting after melting, reducing the fluidity of the slag;

[0022] 3. After adding waste circuit boards, the content of organic impurities in the flue gas generated by smelting is relatively high, making it impossible to recover acid and not meeting the direct emission standard;

[0023] 4. The problem that the desoldering fumes and dust during the disassembly and crushing process of waste circuit boards are not centrally treated, seriously polluting the environment.

[0024] Through in-depth research on the existing mixed smelting process of waste circuit boards and copper concentrates, the present invention discovers many disadvantages in the existing process, and then conducts reasonable equipment transformation and re-designs the process conditions and process route, realizing an industrialized implementation plan for the mixed smelting of waste circuit boards and copper concentrates. By using the recovery system of the present invention, the purpose of fully automatically separating the main valuable metals in the circuit boards can be achieved, and the waste circuit boards containing copper are concentrated, extruded into blocks, and then mixed and smelted with copper concentrates in a certain proportion. During the smelting process, ultra-rich oxygen injection smelting is adopted to fully burn various harmful substances in the waste circuit boards, increasing the calorific value of the flue gas from the mixed smelting of copper concentrates, and using a waste heat recovery boiler to recover this heat. At the same time, the smelting flue gas is purified, enabling the smelting flue gas to be used for the preparation of commercial sulfuric acid. The whole process of the present invention is an automated process, which can not only efficiently and largely process waste circuit boards, but also effectively recover various metals and combustion calorific values in the waste circuit boards, and at the same time achieve the purpose of environmental protection recovery, and can be widely applied to the waste circuit board treatment and recovery industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic connection diagram of the device of the present invention;

[0026] Figure 2 [[ID=I4]]is an enlarged structural schematic diagram of the ultra-rich oxygen spray gun of the present invention.

[0027] In the figure: 1 - waste circuit board storage bin, 2 - desoldering machine, 3 - crusher, 4 - hook separator, 5 - magnetic separator, 6 - screening machine, 7 - eddy current sorter, 8 - first belt conveyor, 9 - hot air supply pipeline, 10 - solder receiving tray, 11 - second belt conveyor, 12 - copper wire collection hopper, 13 - third belt conveyor, 14 - iron-containing material collection hopper, 15 - aluminum block discharge port, 16 - copper block discharge port, 17 - conveyor belt, 18 - aluminum-containing material collection hopper, 19 - copper-containing material collection hopper, 20 - dust collection pipeline, 21 - pulse dust collector, 22 - waste circuit board extruder, 23 - large-volume furnace, 24 - secondary combustion chamber for flue gas, 25 - ultra-rich oxygen spray gun, 26 - melt outlet, 27 - electric furnace, 28 - converter, 29 - refining furnace, 30 - flue, 31 - waste heat recovery boiler, 32 - flue gas electrostatic precipitator, 33 - flue gas purification tower, 34 - sulfur dioxide converter, 35 - sulfuric acid absorption tower, 36 - tail gas absorption tower, 37 - concentrated sulfuric acid spraying device, 38 - valve, 39 - pump, 40 - fan, 41 - concentrated sulfuric acid purification device, 42 - cylindrical shell, 43 - liquid inlet, 44 - liquid outlet, 45 - sewage outlet, 46 - exhaust port, 47 - conical filter plate, 48 - shaker. DETAILED DESCRIPTION OF THE INVENTION

[0028] Example 1

[0029] The technical solution of the present invention is: an efficient and environmentally friendly recycling system for valuable metals from waste circuit boards, including a waste circuit board disassembly and crushing device, a mixed smelting device for waste circuit boards and copper concentrate, and a smelting flue gas purification and recycling device;

[0030] The waste circuit board disassembly and crushing device has a waste circuit board storage bin 1. After the waste circuit board storage bin, there are a desoldering machine 2, a crusher 3, a hook separator 4, a magnetic separator 5, a screening machine 6, and an eddy current sorting machine 7 in sequence. The bottom of the waste circuit board storage bin is provided with an electric bin valve, and the discharge port of the electric bin valve is provided with a first belt conveyor 8. The first belt conveyor conveys the material to the feed port of the desoldering machine 2. The desoldering machine is internally provided with a rolling screen and is connected with a hot air supply pipe 9 to melt and roll off the tin liquid on the material in the desoldering machine. A tin liquid receiving tray 10 is arranged at the bottom of the desoldering machine. The discharge port of the desoldering machine 2 is provided with a second belt conveyor 11, and the second belt conveyor conveys the processed material in the desoldering machine to the feed port of the crusher 3. The crushed material is conveyed from the discharge port of the crusher to the hook separator 4 to hook out the copper wire in the material. A copper wire collection hopper 12 is arranged below the hook separator. The discharge port of the hook separator is provided with a third belt conveyor 13 to convey the material to the screening machine 6. The magnetic separator 5 is located above the third belt conveyor 13, and an iron-containing material collection hopper 14 is arranged at the discharge port of the magnetic separator. After the screening machine 6 screens the material into three specifications of large, medium, and small according to the material size, according to different current settings, it enters the corresponding eddy current sorting machines 7 respectively. The eddy current sorting machines sort the aluminum blocks and copper blocks in the material, and respectively pass through the aluminum block discharge port 15 and the copper block discharge port 16 and fall onto their respective conveyor belts 17 and are conveyed to the aluminum-containing material collection hopper 18 and the copper-containing material collection hopper 19 respectively. Smoke and dust collection pipes 20 are arranged above the waste circuit board storage bin, desoldering machine, crusher, hook separator, and screening machine to collect the smoke and dust generated during the operation of each device and introduce them into a pulse dust collector 21 for dust removal treatment;

[0031] The material collected by the copper-containing material collection hopper 19 is conveyed to a waste circuit board extruder 22, extruded into block materials of 3 - 5 cm in size, and then mixed with copper concentrate and other fluxing auxiliary materials in a certain proportion and enters the mixed smelting device for waste circuit boards and copper concentrate;

[0032] The waste circuit board and copper concentrate mixing and smelting device has a large-volume smelting furnace 23 for receiving waste circuit boards, copper concentrate and other fluxing auxiliary materials for smelting. The lower part of the smelting furnace of the large-volume smelting furnace is a furnace with a diameter of φ5m and a height of 19m, and the upper part is a frustum-shaped secondary flue gas combustion chamber 24 with a diameter gradually decreasing from 3m to 0.5m and a height of 34.7m. An ultra-rich oxygen spray gun 25 is inserted into the large-volume smelting furnace from the furnace mouth, and a spray gun tuyere and a sleeve tuyere are provided on the spray gun, increasing the residence time of the flue gas in the secondary flue gas combustion chamber; a melt outlet 26 is provided at the lower part of the smelting furnace of the large-volume smelting furnace, and an electric furnace 27, a converter 28, and a refining furnace 29 are connected in series in sequence after the liquid outlet, and the melt discharged from the smelting furnace is sequentially subjected to electric furnace sedimentation, converter smelting, and refining furnace refining to extract copper and other valuable metals; a flue 30 is connected to the upper part of the secondary flue gas combustion chamber 24 to convey the flue gas to a waste heat recovery boiler 31 to recover heat, and the flue gas coming out of the waste heat recovery boiler 31 is input into a smelting flue gas purification and recovery device;

[0033] The smelting flue gas purification and recovery device is located behind the waste heat recovery boiler and includes a flue gas electrostatic precipitator 32, a flue gas purification tower 33, a sulfur dioxide converter 34, a sulfuric acid absorption tower 35, and a tail gas absorption tower 36 connected in series in sequence. The flue gas coming out of the waste heat recovery boiler 31 is purified twice by the flue gas electrostatic precipitator 32 and the flue gas purification tower 33 and then enters the sulfur dioxide converter 24 to be converted into sulfur trioxide, and then is absorbed by the sulfuric acid absorption tower 35 to produce concentrated sulfuric acid; a flue gas inlet is provided at the bottom of the flue gas purification tower 33, and a concentrated sulfuric acid spraying device 37 and a flue gas outlet are provided at the top; in the tail gas absorption tower 36, hydrogen peroxide is sprayed to absorb the remaining sulfur trioxide and sulfur dioxide in the flue gas and then discharged;

[0034] Valves 38, pumps 39 or fans 40 are installed on the connecting pipes between the above devices as required.

[0035] The ultra-rich oxygen spray gun 25 is composed of four concentric steel cylinders. Pulverized coal, oxygen, spray gun air, and sleeve air are introduced into the four concentric steel cylinders from the inside to the outside in sequence, and the air inlets of oxygen, spray gun air, and sleeve air are opened on the side walls of the concentric steel cylinders in sequence.

[0036] A concentrated sulfuric acid purification device 41 is also provided on one side of the flue gas purification tower 33. The concentrated sulfuric acid purification device has a cylindrical outer shell 42, a liquid inlet 43 is provided at the lower part, a liquid outlet 44 is provided at the upper part, a sewage outlet 45 is provided at the bottom, and an exhaust outlet 46 is provided at the top. Inside the cylindrical outer shell, three conical filter plates 47 made of polymer materials are installed in sequence from bottom to top. The diameters of the filter holes on the three polymer filter plates decrease from bottom to top in sequence. The contaminated concentrated sulfuric acid liquid enters from the lower liquid inlet and then passes through the three filter plates in sequence and is discharged through the liquid outlet, and is circulated and pumped into the concentrated sulfuric acid spraying device 37 at the top of the flue gas purification tower 33.

[0037] A plurality of vibrators 48 are also installed on the outer wall of the flue 30.

[0038] The above embodiments are merely exemplary explanations of the claims of the present invention and do not limit the present invention in any form. Anyone who makes equivalent changes, amplifications or reductions within the scope based on the principles of the claims of the present invention shall be regarded as falling within the protection scope of the claims of the present invention.

Claims

1. An efficient and environmentally friendly recovery system for valuable metals from waste circuit boards, characterized in that: It includes a waste circuit board disassembly and crushing device, a waste circuit board and copper concentrate mixed smelting device, and a smelting flue gas purification and recovery device; The waste circuit board disassembly and crushing device has a waste circuit board storage bin. After the waste circuit board storage bin, a desoldering machine, a crusher, a hook separator, a magnetic separator, a screening machine, and an eddy current sorter are successively arranged. An electric bin valve is provided at the bottom of the waste circuit board storage bin, and a first belt conveyor is provided at the discharge port of the electric bin valve. The first belt conveyor conveys the material to the feed port of the desoldering machine. A rolling screen is built in the desoldering machine, and a hot air supply pipe is connected to melt and roll off the tin liquid on the material in the desoldering machine. A tin liquid receiving tray is provided at the bottom of the desoldering machine. A second belt conveyor is provided at the discharge port of the desoldering machine, and the second belt conveyor conveys the processed material in the desoldering machine to the feed port of the crusher. The crushed material is conveyed from the discharge port of the crusher to the hook separator to hook out the copper wire in the material. A copper wire collection hopper is provided below the hook separator. A third belt conveyor is provided at the discharge port of the hook separator to convey the material to the screening machine. The magnetic separator is located above the third belt conveyor, and an iron-containing material collection hopper is provided at the discharge port of the magnetic separator. After the screening machine screens the material into three specifications of large, medium, and small according to the material size, according to different current settings, it enters the corresponding eddy current sorters respectively. The eddy current sorters sort the aluminum blocks and copper blocks in the material, and respectively fall through the aluminum block discharge port and the copper block discharge port onto their respective conveyor belts and are conveyed to the aluminum-containing material collection hopper and the copper-containing material collection hopper; The material collected by the copper-containing material collection hopper is conveyed to a waste circuit board extruder, extruded into blocks with a size of 3 - 5 cm, and then mixed with copper concentrate and other fluxing auxiliary materials in a certain proportion and enters the waste circuit board and copper concentrate mixed smelting device; The waste circuit board and copper concentrate mixed smelting device has a large-volume smelting furnace used to receive waste circuit boards, copper concentrate, and other fluxing auxiliary materials for smelting. The lower part of the furnace of the large-volume smelting furnace is a furnace with a diameter of φ5m and a height of 19m, and the upper part is a frustum-shaped secondary flue gas combustion chamber with a diameter gradually decreasing from 3m to 0.5m and a height of 34.7m. A super-oxygen-enriched spray gun is inserted into the large-volume smelting furnace from the furnace mouth, and a spray gun tuyere and a sleeve tuyere are provided on the spray gun, increasing the residence time of the flue gas in the secondary flue gas combustion chamber. A melt outlet is provided at the lower part of the furnace of the large-volume smelting furnace, and an electric furnace, a converter, and a refining furnace are successively connected in series after the melt outlet to successively carry out electric furnace sedimentation, converter smelting, and refining furnace refining on the melt discharged from the smelting furnace to extract copper and other valuable metals. The upper part of the secondary flue gas combustion chamber is connected with a flue to convey the flue gas to a waste heat recovery boiler to recover heat, and the flue gas coming out of the waste heat recovery boiler is input into the smelting flue gas purification and recovery device; The smelting flue gas purification and recovery device is located behind the waste heat recovery boiler. It includes a flue gas electrostatic precipitator, a flue gas purification tower, a sulfur dioxide converter, a sulfuric acid absorption tower, and a tail gas absorption tower connected in series in sequence. The flue gas coming out of the waste heat recovery boiler is purified twice by the flue gas electrostatic precipitator and the flue gas purification tower, then enters the sulfur dioxide converter to be converted into sulfur trioxide, and is then absorbed by the sulfuric acid absorption tower to produce concentrated sulfuric acid; a flue gas inlet is provided at the bottom of the flue gas purification tower, and a concentrated sulfuric acid spraying device and a flue gas outlet are provided at the top; in the tail gas absorption tower, hydrogen peroxide is sprayed to absorb the remaining sulfur trioxide and sulfur dioxide in the flue gas and then discharged; Valves, pumps or fans are installed on the connecting pipes between the above-mentioned devices as required; Dust collection pipes are provided above the waste circuit board storage bin, the tin removal machine, the crusher, the hook separator, and the screening machine. After collecting the dust generated during the operation of each device, it is introduced into a pulse dust collector for dust removal treatment; The structure of the ultra-oxygen-enriched lance is made of four concentric steel cylinders. Pulverized coal, oxygen, lance air, and sleeve air are introduced into the four concentric steel cylinders from the inside to the outside in sequence. The air inlets of oxygen, lance air, and sleeve air are opened on the side walls of the concentric steel cylinders in sequence; A concentrated sulfuric acid purification device is also provided on one side of the flue gas purification tower. The concentrated sulfuric acid purification device has a cylindrical outer shell, a liquid inlet is provided at the lower part, a liquid outlet is provided at the upper part, a sewage outlet is provided at the bottom, and an exhaust outlet is provided at the top. Inside the cylindrical outer shell, three conical filter plates made of polymer materials are installed in sequence from bottom to top. The pore diameters of the three polymer filter plates decrease from bottom to top in sequence. The contaminated concentrated sulfuric acid liquid enters from the lower liquid inlet and then passes through the three filter plates in sequence and is discharged through the liquid outlet, and is circulated and pumped into the concentrated sulfuric acid spraying device at the top of the flue gas purification tower.

2. The high-efficiency and environmentally friendly recycling system for valuable metals from waste circuit boards according to claim 1, wherein: Several shakers are also installed on the outer wall of the flue.

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