Method for recycling copper, gold and tin from waste circuit board

Abstract

The present application relates to a kind of copper, gold, tin recovery method of waste circuit board, which includes the following steps: (1) the waste circuit board is placed in the vibration screen in vacuum vibration separation container, and vacuum vibration separation is carried out;Through vibration, the molten lead tin in waste circuit board flows into alloy collection pool in the bottom of container, and lead-tin alloy is formed;Circuit board base material, conducting circuit, electronic component remain on the vibration screen;(2) the circuit board with conducting circuit and electronic component attached to vibration screen are taken down, and high-efficiency separation is carried out in large-aperture vibration screen bed, to obtain resin circuit board with conducting circuit attached and waste electronic component;(3) resin circuit board with conducting circuit attached is loaded into circuit board plug-in grid in high-temperature high-pressure hot air blowing selection container, and high-temperature high-pressure hot air blowing selection is carried out, and copper skin enters copper skin collection pool;(4) gold in waste electronic component is recovered after being crushed by crushing equipment, and gold is recovered by using thiourea method.The method is simple, pollution-free, low in cost, and high in metal separation efficiency.

Description

Technical Field

[0001] This invention relates to the field of waste electronic and electrical appliance recycling technology, and in particular to a method for recycling copper, gold, and tin from waste circuit boards. Background Technology

[0002] The advent of electronic products has brought immense convenience to people's lives. However, with the continuous development of the electronics industry, the amount of electronic waste generated is increasing at a rate of 18% annually, making it the fastest-growing type of waste in the world and gradually becoming a focus of social concern. Circuit boards are among the most complex components in all electronic products, making direct recycling extremely difficult and disassembly and reuse costly. If left untreated, they not only waste resources but, if improperly handled, can also cause serious environmental problems, impacting human health and development.

[0003] Common circuit boards are mainly composed of insulating substrate, bonded conductive circuits, and soldered electronic components. They contain valuable metals such as copper, iron, nickel, tin, and lead with high recycling value, as well as precious metals such as gold, silver, and palladium, accounting for about 40% of the circuit board. They are one of the important valuable metal "mines" resources.

[0004] Currently, the main technologies for recycling waste circuit boards are mechanical and metallurgical methods. The mechanical method involves crushing and pulverizing waste circuit boards in crushing equipment to obtain a mixed powder of the board's substrate, bonded conductive circuitry, and soldered electronic components. This powder is then processed through physical methods such as airflow separation and electrostatic separation to largely separate the metals from the non-metals, yielding resin powder and copper-based powder. However, because this technology pulverizes the circuit board and its attached components, the separation between metals and between metal and resin is incomplete, resulting in low metal purity. The goal of recycling metals from electronic waste is to maximize the recovery of valuable components and obtain the highest possible metal purity, but this technology cannot achieve this. Some researchers have used chemical methods to separate the metals from the circuit board. This technology belongs to hydrometallurgy, where the metals from the circuit board are introduced into a leaching solution using a leaching agent, and then the metals are extracted from the leaching solution using metal extraction methods. Because this method uses large amounts of chemical reagents and generates significant amounts of wastewater and waste, it causes serious environmental pollution. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an efficient, low-cost and environmentally friendly method for recycling copper, gold and tin from waste circuit boards.

[0006] To address the above problems, the present invention provides a method for recycling copper, gold, and tin from waste circuit boards, comprising the following steps:

[0007] (1) Place the waste circuit board on the vibrating screen in the vacuum vibration separation container, turn on the temperature control switch to heat the heating plate to 200~300℃, keep it at that temperature for 30 minutes, and then turn on the vibrating screen to separate the substrate, conductive circuit and electronic components under vacuum vibration; the molten lead and tin in the waste circuit board flows into the alloy collection pool at the bottom of the container through vibration to form a lead-tin alloy; the circuit board substrate, conductive circuit and electronic components remain on the vibrating screen.

[0008] (2) Remove the circuit board and electronic components with conductive circuits from the vibrating screen and separate them efficiently in a large-aperture vibrating screen bed to obtain resin circuit boards with conductive circuits and waste electronic components.

[0009] (3) The resin circuit board with the attached conductive circuit is placed into the circuit board insertion grid in the high-temperature and high-pressure hot air blowing container, so that the circuit board is arranged perpendicular to the circuit board insertion grid and the perpendicular angle between the circuit board and the circuit board insertion grid is maintained at 90°±5°. Then, high-temperature and high-pressure hot air blowing is performed. At this time, the metal conductive circuit, i.e., the copper foil, on the circuit board separates from the circuit board and enters the copper foil collection pool with a dense mesh grid with the high-pressure air, which is reused as the main raw material for copper recycling. The separated circuit board remains on the circuit board insertion grid and is taken out and reused as a resin substrate.

[0010] (4) After the waste electronic components are crushed by the crushing equipment, the gold in them is recovered using the thiourea method.

[0011] In step (1), the waste circuit board refers to a circuit board whose substrate material is resin.

[0012] The conditions for vacuum vibration separation in step (1) are a vacuum degree of 0.05~0.07KPa and a strong vibration.

[0013] In step (1), the vacuum vibration separation container includes an upper end cover I, a lower end cover I, and a heating separation chamber connected together. The heating separation chamber contains a pair of heating plates and a vibrating screen. A vibration motor is located on the top of the upper end cover I, and its output shaft is connected to a vibration shaft. The vibration shaft passes through the upper end cover I and is connected to the vibrating screen. A vacuum tube interface is located at the top of the heating separation chamber, and this interface is connected to a vacuum pump via a pipeline. A pair of heating plates are symmetrically arranged on both sides of the vibrating screen, which has a circuit board holding platform. An alloy collection pool is located below the vibrating screen. A temperature control switch is externally connected to each heating plate.

[0014] A sealing sleeve is provided at the junction of the vibration shaft and the heating separation chamber.

[0015] In step (2), the diameter of the sieve holes in the large-aperture vibrating sieve bed is 1~5cm.

[0016] The conditions for high-temperature and high-pressure hot air separation in step (3) are: air pressure of 0.2~0.5MPa, separation temperature of 320~400℃, and high-pressure washing and separation time of 30min.

[0017] In step (3), the high-temperature and high-pressure hot air blowing container includes a container shell with an upper end cover II and a lower end cover II, and a circuit board insertion grid placed inside the container shell; a copper collection pool is provided below the circuit board insertion grid; several high-pressure hot air guns connected to a blower are evenly distributed on the upper end cover II; a discharge port is provided on the lower end cover II; a set of air outlets are symmetrically provided on the lower side wall of the container shell and below the circuit board insertion grid, and the air outlets are provided with dense mesh grids.

[0018] The circuit board insertion grille is located in the middle of the container shell.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention is equipped with a vacuum vibration separation container, which uses vibration to draw molten tin from waste circuit boards into a tin collection pool at the bottom of the container to form a lead-tin alloy; while the circuit board substrate, conductive circuit, and electronic components remain on the vibrating screen, thereby solving the problem that the metallic tin cannot be recycled after the waste circuit boards are directly crushed.

[0021] 2. The present invention includes a large-aperture vibrating screen bed, the purpose of which is to effectively separate resin circuit boards with attached conductive circuits and waste electronic components.

[0022] 3. The present invention is equipped with a high-temperature and high-pressure hot air blowing container, which effectively separates the copper foil from the circuit board by blowing with a high-pressure hot air gun.

[0023] 4. The method of this invention not only has high metal separation efficiency, but also high material recovery rate.

[0024] 5. The method of the present invention is simple, pollution-free, and low-cost. Attached Figure Description

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0026] Figure 1 This is a process flow diagram of the present invention.

[0027] Figure 2 This is a schematic diagram of the vacuum vibration separation container in this invention.

[0028] Figure 3 This is a schematic diagram of the structure of the high-temperature and high-pressure hot air blowing container in this invention.

[0029] In the diagram: 1—Vacuum vibration separation container; 11—Vibration motor; 12—Vibration shaft; 13—Sealing sleeve; 14—Heating separation chamber; 15—Circuit board holding platform; 16—Heating plate; 17—Vibrating screen; 18—Alloy collection tank; 19—Vacuum pump; 2—Large aperture vibrating screen bed; 3—High temperature and high pressure hot air blowing container; 31—High pressure hot air gun; 32—Container shell; 33—Air outlet; 34—Circuit board insertion grid; 35—Copper collection tank; 4—Crushing equipment. Detailed Implementation

[0030] like Figure 1 As shown, a method for recycling copper, gold, and tin from waste circuit boards includes the following steps:

[0031] (1) Place the waste circuit board on the vibrating screen 17 in the vacuum vibration separation container 1, turn on the temperature control switch to heat the heating plate 16 to 200~300℃, keep it at that temperature for 30 minutes, then turn on the vibrating screen 17 to separate the substrate, conductive circuit, and electronic components under vacuum vibration. The conditions for vacuum vibration separation are a vacuum degree of 0.05~0.07KPa and strong vibration. The molten lead and tin in the waste circuit board flow into the alloy collection pool 18 at the bottom of the container through vibration, forming a lead-tin alloy; the circuit board substrate, conductive circuit, and electronic components remain on the vibrating screen 17.

[0032] Among them, waste circuit boards refer to circuit boards whose substrate material is resin.

[0033] Vacuum vibration separation container 1 Figure 2 As shown, the device includes an upper end cover I, a lower end cover I, and a heating separation chamber 14 connected together. The heating separation chamber 14 contains a pair of heating plates 16 and a vibrating screen 17 with a mesh diameter of 5-10 mm. A vibration motor 11 is located on the top of the upper end cover I, and the output shaft of the vibration motor 11 is connected to a vibration shaft 12. The vibration shaft 12 passes through the upper end cover I and connects to the vibrating screen 17. A sealing sleeve 13 is provided at the junction of the vibration shaft 12 and the heating separation chamber 14. A vacuum tube interface is located at the top of the heating separation chamber 14, and this interface is connected to a vacuum pump 19 via a pipeline. A pair of heating plates 16 are symmetrically arranged on both sides of the vibrating screen 17, which has a circuit board holding platform 15. An alloy collection pool 18 is located below the vibrating screen 17. Temperature control switches are externally connected to the heating plates 16.

[0034] How to use the vacuum vibration separation container 1: Open the upper cover I and fill the waste circuit board into it for processing. After a certain amount of alloy has accumulated in the alloy collection pool 18, stop the separator from working for a period of time. Then open the lower cover I, take out the alloy from the lower cover I, and then close the lower cover I.

[0035] (2) Remove the circuit board and electronic components with conductive circuitry from the vibrating screen 17, and efficiently separate them in the large-aperture vibrating screen bed 2 to obtain the resin circuit board with conductive circuitry attached and the waste electronic components. The diameter of the screen holes in the large-aperture vibrating screen bed 2 is 1~5cm.

[0036] (3) The resin circuit board with the attached conductive circuit is placed onto the circuit board insertion grid 34 in the high-temperature and high-pressure hot air blowing container 3, so that the circuit board and the circuit board insertion grid 34 are arranged perpendicularly, and the perpendicular angle between the circuit board and the circuit board insertion grid 34 is maintained at 90°±5°. Then, high-temperature and high-pressure hot air blowing is performed. The conditions for high-temperature and high-pressure hot air blowing are that the air pressure is 0.2~0.5MPa, the blowing temperature is 320~400℃, and the high-pressure blowing separation time is 30min. At this time, the metal conductive circuit, i.e., the copper foil, on the circuit board separates from the circuit board and enters the copper foil collection pool 35 with a dense mesh grid with the high-pressure air, which is reused as the main raw material for copper recovery. The separated circuit board remains on the circuit board insertion grid 34 and is taken out and reused as a resin substrate.

[0037] Among them: high temperature and high pressure hot air blowing container 3, such as Figure 3 As shown, the container includes a container shell 32 with an upper end cover II and a lower end cover II, and a circuit board insertion grid 34 placed inside the container shell 32; a copper collection pool 35 is provided below the circuit board insertion grid 34; several high-pressure hot air guns 31 connected to a fan are evenly distributed on the upper end cover II; a discharge port is provided on the lower end cover II; a set of air outlets 33 are symmetrically provided on the lower side wall of the container shell 32 and below the circuit board insertion grid 34, and the air outlets 33 are provided with dense mesh grids.

[0038] The circuit board insertion grille 34 is located in the middle of the container shell 32.

[0039] How to use the high temperature and high pressure hot air blowing container 3: Open the upper cover II, hoist the material into the circuit board insertion grid 34, collect a certain amount with copper foil, stop the container working for a period of time, and then open the discharge port of the lower cover II to take it out.

[0040] (4) After the waste electronic components are crushed by the crushing equipment 4, the gold is recovered by the thiourea method.

[0041] An embodiment of a method for recycling copper, gold, and tin from waste circuit boards includes the following steps:

[0042] (1) 2000g of 10 waste circuit boards with resin substrates were placed on a vibrating screen 17 in a vacuum vibration separation container 1. The container was evacuated and heated to 280℃. The molten lead and tin in the waste circuit boards were separated by vibration. The vibration was strong, and the processing time was 30min. The lead and tin entered the alloy collection pool 18 at the bottom of the container. The obtained lead-tin alloy weighed 106g, with a tin content of 80% and a recovery rate of 95.3%.

[0043] (2) Take 1890 grams of circuit boards and electronic components with conductive circuits from vibrating screen 17 and separate them efficiently in large-aperture vibrating screen bed 2. 1530 grams of circuit boards with conductive circuits are obtained on the screen and 360 grams of waste electronic components are obtained below the screen.

[0044] (3) The resin circuit board with the attached conductive circuit is placed into the circuit board insertion grid 34 in the high temperature and high pressure hot air separation container 3, so that the circuit board and the circuit board insertion grid 34 are arranged perpendicularly. Then, high temperature and high pressure hot air separation is carried out. The system air pressure is 0.3MPa, the temperature is 350℃, and the high pressure separation time is 30min. The copper skin on the circuit board is separated from the circuit board and enters the copper skin collection pool 35 with the high pressure air. It is reused as the main raw material for copper recovery. The copper skin weighs 250g and the recovery rate is 96%. The high pressure air returns to the blower from the air outlet 33 for reheating. The resin board with the copper skin removed is taken out and reused as a resin substrate.

[0045] (4) After the waste electronic components are crushed by crushing equipment 4, the gold is recovered using the thiourea method. The recovered gold is 1.8 grams, with a recovery rate of 98.5%.

Claims

1. A method for recycling copper, gold and tin from waste circuit boards, comprising the following steps: (1) placing the waste circuit boards on a vibrating screen (17) in a vacuum vibration separation container (1), turning on the temperature control switch to heat the heating plates (16) to 200-300℃, and then turning on the vibrating screen (17) after 30 minutes of heat preservation to separate the base material, conductive circuit and electronic components by vacuum vibration; molten lead and tin in the waste circuit boards flow into the alloy collection pool (18) at the bottom of the container by vibration to form a lead-tin alloy; the circuit board base material, conductive circuit and electronic components remain on the vibrating screen (17); the waste circuit boards refer to circuit boards with resin as the base material; the vacuum vibration separation container (1) comprises an upper end cover I, a lower end cover I and a heating separation cavity (14) connected together; a pair of heating plates (16) and a vibrating screen (17) are arranged in the heating separation cavity (14); a vibration motor (11) is arranged on the top of the upper end cover I, and a vibration shaft (12) is connected to the output shaft of the vibration motor (11); the vibration shaft (12) penetrates through the upper end cover I and is connected to the vibrating screen (17); a vacuum pipe interface is arranged on the upper part of the heating separation cavity (14), and a vacuum pump (19) is connected to the vacuum pipe interface through a pipeline; a pair of heating plates (16) are symmetrically arranged on both sides of the vibrating screen (17), and a circuit board containing table (15) is arranged on the vibrating screen (17); an alloy collection pool (18) is arranged below the vibrating screen (17); the heating plates (16) are connected to a temperature control switch; (2) taking the circuit boards with conductive circuits and electronic components from the vibrating screen (17), and separating them in a large-aperture vibrating screen bed (2) to obtain resin circuit boards with conductive circuits and waste electronic components; (3) loading the resin circuit boards with conductive circuits into a circuit board plug-in grid (34) in a high-temperature and high-pressure hot air blowing container (3), arranging the circuit boards vertically to the circuit board plug-in grid (34), and keeping the vertical angle between the circuit boards and the circuit board plug-in grid (34) at 90°±5°, and then blowing and selecting by high-temperature and high-pressure hot air, so that the metal conductive circuit, i.e. copper skin, on the circuit boards is separated from the circuit boards, enters a copper skin collection pool (35) with a dense grid through high-pressure wind, and is reused as a main raw material for recycling copper; the separated circuit boards remain on the circuit board plug-in grid (34) and are taken out for reuse as resin base material; the high-temperature and high-pressure hot air blowing container (3) comprises a container shell (32) with an upper end cover II and a lower end cover II and a circuit board plug-in grid (34) arranged in the container shell (32); a copper skin collection pool (35) is arranged below the circuit board plug-in grid (34); a plurality of high-pressure hot air guns (31) connected to a fan are uniformly distributed on the upper end cover II; a discharge port is arranged on the lower end cover II; a group of air outlets (33) with dense grids are symmetrically arranged on the lower part of the side wall of the container shell (32) and below the circuit board plug-in grid (34). (4) After the waste electronic components are crushed by the crushing equipment (4), the gold in them is recovered by the thiourea method.

2. The method for recovering copper, gold and tin from waste circuit board according to claim 1, characterized in that: The conditions for vacuum vibration separation in step (1) are a vacuum degree of 0.05~0.07KPa and a strong vibration.

3. The method for recovering copper, gold and tin from waste circuit board according to claim 1, characterized in that: A sealing sleeve (13) is provided at the junction of the vibration shaft (12) and the heating separation chamber (14).

4. The method for recovering copper, gold and tin from waste circuit board according to claim 1, characterized in that: In step (2), the diameter of the sieve holes in the large-aperture vibrating sieve bed (2) is 1~5cm.

5. The method for recovering copper, gold and tin from waste circuit board according to claim 1, characterized in that: The conditions for high-temperature and high-pressure hot air separation in step (3) are: air pressure of 0.2~0.5MPa, separation temperature of 320~400℃, and high-pressure washing and separation time of 30min.

6. The method for recovering copper, gold and tin from waste circuit board according to claim 1, characterized in that: The circuit board insertion grille (34) is located in the middle of the container shell (32).

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