Method for recovering copper from waste circuit

Abstract

The invention provides a method for recycling copper from a waste circuit, and belongs to the technical field of waste circuit board recycling. The method for recovering copper from the waste circuit board comprises the following steps: (1) crushing and sorting: mechanically crushing and sorting the waste circuit board to obtain metal particles enriched with copper; (2) preleaching is conducted, specifically, the metal particles and a dilute sulfuric acid solution are mixed, a preleaching reaction is conducted, and preleaching residues and preleaching liquid are obtained; (3) electrolytic deposition is conducted, specifically, the pre-leaching liquid serves as electrolyte, electrolytic deposition is conducted, and high-purity copper deposits are obtained; and (4) post-treatment is conducted, specifically, the copper sediment is washed and dried, and recycled copper is obtained. According to the technical scheme, no harmful gas or waste water is generated in the whole recycling process, environmental pollution is small, leaching and electro-deposition of copper can be conducted in the same device, the technological process is shortened, and energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of waste circuit board recycling, in particular to a method for recycling copper from waste circuit boards. Background Art

[0002] With the rapid development of electronic technology, the speed of electronic product replacement is accelerating. This has led to the generation of a large number of waste circuit boards, which not only contain toxic and harmful substances such as organic plastics and polybrominated biphenyls, but also rich in precious metals such as copper, aluminum, gold, and silver. If not handled properly, it will cause serious pollution to the environment and waste recyclable resources. Waste circuit boards contain harmful substances such as lead and mercury. If they are directly landfilled or incinerated without treatment, they will cause serious pollution to the soil, water sources and air. Professional recycling can effectively prevent these harmful substances from leaking into the natural environment and protect the safety of the ecological environment. At the same time, the waste gas and wastewater generated during the recycling process are strictly treated and discharged in compliance with the standards, ensuring the green and environmental protection of the entire recycling chain.

[0003] The metal resources in waste circuit boards have a high recycling value. Through scientific recycling treatment, precious metals and non-metallic components in circuit boards can be extracted. After purification and processing, these resources can be used again in the manufacture of electronic products or other industrial fields, greatly reducing the demand for mining primary mineral resources. This is in line with the concept of circular economy, that is, applying the closed-loop economic model of "resources-products-renewable resources" to the treatment of electronic waste, which helps to achieve sustainable utilization of resources.

[0004] Copper is an important metal resource and is widely used in electronics, electrical, construction, transportation and other fields. With the rapid development of the global economy, the demand for copper continues to grow, but its primary mineral resources are becoming increasingly depleted. Waste circuit boards contain a large amount of copper, which can be effectively extracted through recycling and processing to alleviate the problem of resource shortage. At the same time, recycling copper can also reduce the pressure on the mining of primary mineral resources, reduce energy consumption and environmental pollution. With the rapid development of the electronics industry, the production and manufacturing of circuit boards has increased year by year. As an important component of circuit boards, copper has good electrical conductivity and thermal conductivity and is widely used in various industries. Therefore, recovering copper from waste circuit boards has become an important topic.

[0005] Circuit boards are generally composed of glass fiber cloth base material and copper foil. The glass fiber cloth base material and copper foil are tightly combined and difficult to separate. At present, physical and chemical methods are mostly used to recover copper. The current physical method is to use the differences in density and magnetism of different substances after the waste circuit boards are crushed, and use gas, fluid, gravity, magnetism, etc. to achieve the purpose of separation, but it can only recover 70-80% of the metal, and fails to completely solve the problem of separation of metal and non-metal. At the same time, the result of crushing makes the valuable glass fiber become unusable waste, and also complicates the subsequent metal and non-metal processing; the chemical method uses hydrometallurgical methods such as strong acid to separate and extract metallic copper, but it will produce toxic wastewater, and the discharge of wastewater will cause environmental pollution.

[0006] Based on this, it is of great practical significance to provide a method for recovering copper from waste circuits with high recovery rate and low environmental pollution. Summary of the invention

[0007] The purpose of the present invention is to provide a method for recovering copper from waste circuits, aiming to solve the technical problems in the prior art such as low recovery rate of precious metals from waste circuit boards and harm to the environment.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for recovering copper from waste circuits, comprising the following steps:

[0010] (1) Crushing and sorting: Mechanically crushing and sorting the waste circuit boards to obtain copper-enriched metal particles;

[0011] (2) Preleaching: mixing the metal particles with a dilute sulfuric acid solution to perform a preleaching reaction to obtain preleaching residue and preleaching liquid;

[0012] (3) Electrolytic deposition: using the pre-leaching solution as an electrolyte to perform electrolytic deposition to obtain a high-purity copper deposit;

[0013] (4) Post-treatment: washing and drying the copper deposit to obtain recovered copper.

[0014] Furthermore, the sorting method is one or more of vibration screen sorting, air flow sorting or electrostatic sorting.

[0015] Furthermore, the concentration of the dilute sulfuric acid solution is 0.01-0.5 mol / L.

[0016] Furthermore, the pre-leaching temperature is 40-60° C. and the pre-leaching time is 1-2 hours.

[0017] Furthermore, ammonium chloride and ammonia water are added to the electrolyte.

[0018] Furthermore, the mass ratio of the ammonium chloride, ammonia water and pre-leaching solution is 1:1:2-3.

[0019] Furthermore, the concentration of the ammonium chloride is 0.01-0.1 mol / L.

[0020] Furthermore, the concentration of the ammonia water is 0.01-0.2 mol / L.

[0021] Furthermore, the current density of the electrolytic deposition is 30 to 35 A / m 2 The electrolysis time is 3 to 5 hours.

[0022] Furthermore, the temperature of the electrolyte is 30-35°C.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] (1) The entire recycling process of the technical solution of the present invention does not produce harmful gases and wastewater, and has little environmental pollution;

[0025] (2) The present invention uses an acid solution for leaching, and the copper leaching rate and recovery rate are high during the electrolytic deposition process. In addition, the present invention can perform copper leaching and electrolytic deposition in the same device, shortening the process flow and reducing energy consumption;

[0026] (3) The method of the present invention is simple, easy to operate, suitable for large-scale industrial production, and has good economic benefits. DETAILED DESCRIPTION

[0027] The metal resources in waste circuit boards have a high recycling value. Through scientific recycling treatment, precious metals and non-metallic components in circuit boards can be extracted. After purification and processing, these resources can be used again in the manufacture of electronic products or other industrial fields, greatly reducing the demand for mining primary mineral resources. This is in line with the concept of circular economy, that is, applying the closed-loop economic model of "resources-products-renewable resources" to the treatment of electronic waste, which helps to achieve sustainable utilization of resources.

[0028] Copper is an important metal resource and is widely used in electronics, electrical, construction, transportation and other fields. With the rapid development of the global economy, the demand for copper continues to grow, but its primary mineral resources are becoming increasingly depleted. Waste circuit boards contain a large amount of copper, which can be effectively extracted through recycling and processing to alleviate the problem of resource shortage. At the same time, recycling copper can also reduce the pressure on the mining of primary mineral resources, reduce energy consumption and environmental pollution. With the rapid development of the electronics industry, the production and manufacturing of circuit boards has increased year by year. As an important component of circuit boards, copper has good electrical conductivity and thermal conductivity and is widely used in various industries. Therefore, recovering copper from waste circuit boards has become an important topic.

[0029] Circuit boards are generally composed of glass fiber cloth base material and copper foil. The glass fiber cloth base material and copper foil are tightly combined and difficult to separate. At present, physical and chemical methods are mostly used to recover copper. The current physical method is to use the differences in density and magnetism of different substances after the waste circuit boards are crushed, and use gas, fluid, gravity, magnetism, etc. to achieve the purpose of separation, but it can only recover 70-80% of the metal, and fails to completely solve the problem of separation of metal and non-metal. At the same time, the result of crushing makes the valuable glass fiber become unusable waste, and also complicates the subsequent metal and non-metal processing; the chemical method uses hydrometallurgical methods such as strong acid to separate and extract metallic copper, but it will produce toxic wastewater, and the discharge of wastewater will cause environmental pollution.

[0030] Based on this, it is of great practical significance to provide a method for recovering copper from waste circuits with high recovery rate and low environmental pollution.

[0031] The present invention provides a method for recovering copper from waste circuits, comprising the following steps:

[0032] (1) Crushing and sorting: Mechanically crushing and sorting the waste circuit boards to obtain copper-enriched metal particles;

[0033] (2) Preleaching: mixing the metal particles with a dilute sulfuric acid solution to perform a preleaching reaction to obtain preleaching residue and preleaching liquid;

[0034] (3) Electrolytic deposition: using the pre-leaching solution as an electrolyte to perform electrolytic deposition to obtain a high-purity copper deposit;

[0035] (4) Post-treatment: washing and drying the copper deposit to obtain recovered copper.

[0036] In the present invention, the sorting method is one or more of vibration screen sorting, air flow sorting or electrostatic sorting.

[0037] The present invention firstly mechanically crushes the waste circuit boards to facilitate soaking treatment of the waste circuit boards. The size of the crushed waste circuit boards is not particularly limited, which is convenient for technicians in the field to actually operate. Then, they are sorted. Multiple sorting methods can be used in combination or only one sorting method can be used. There is no special limitation on the combination of sorting methods, which can be adjusted according to actual applications.

[0038] In the present invention, the concentration of the dilute sulfuric acid solution is preferably 0.01 to 0.5 mol / L, and more preferably 0.01 to 0.2 mol / L.

[0039] The present invention adopts an acid solution for leaching, and the leaching rate and recovery rate of copper are high during the electrolytic deposition process. In addition, the present invention can carry out copper leaching and electrolytic deposition in the same device, shortening the process flow, reducing energy consumption, and helping to improve the recovery rate of copper.

[0040] In the present invention, the pre-leaching temperature is preferably 40 to 60° C., more preferably 40 to 50° C.; the pre-leaching time is preferably 1 to 2 hours, more preferably 1 to 1.5 hours.

[0041] The present invention specifically limits the leaching temperature, so that the dissolution rate of the waste circuit board in the solution is increased, and the leaching rate of copper in the waste circuit board is further improved.

[0042] In the present invention, ammonium chloride and ammonia water are preferably added to the electrolyte.

[0043] In the present invention, the mass ratio of the ammonium chloride, the ammonia water and the pre-leaching solution is preferably 1:1:2-3, and more preferably 1:1:2.

[0044] In the present invention, the concentration of ammonium chloride is preferably 0.01 to 0.1 mol / L, and more preferably 0.01 to 0.05 mol / L.

[0045] In the present invention, the concentration of the ammonia water is preferably 0.01 to 0.2 mol / L, and more preferably 0.01 to 0.1 mol / L.

[0046] In the present invention, the current density of the electrolytic deposition is preferably 30 to 35 A / m 2 , more preferably 30 to 32 A / m 2 The electrolysis time is preferably 3 to 5 hours, more preferably 3 to 4 hours.

[0047] In the present invention, the temperature of the electrolyte is preferably 30-35°C, more preferably 30-32°C. 。

[0048] The entire recycling process of the technical solution of the present invention does not produce harmful gases and wastewater, and has little environmental pollution; and the method of the present invention is simple, easy to operate, suitable for large-scale industrial production, has good economic benefits, and can quickly carry out production and recycling.

[0049] In the present invention, unless otherwise specified, the required raw materials for preparation are all commercially available products well known to those skilled in the art.

[0050] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0051] Example 1

[0052] (1) Crushing and sorting: The waste circuit boards to be recycled are mechanically crushed, and after crushing, the metals and non-metals are separated by vibration screening and air flow sorting to obtain enriched metal particles:

[0053] (2) Preleaching: mixing the above metal particles with a dilute hydrochloric acid solution with a concentration of 0.01 mol / L, and leaching at a temperature of 40° C. for 1 hour to obtain preleaching residue and preleaching liquid;

[0054] (3) Electrolytic deposition: ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:2, wherein the concentration of ammonium chloride was 0.01 mol / L and the concentration of ammonia water was 0.01 mol / L to obtain an electrolyte. The temperature of the electrolyte was controlled at 30°C and the current density was 30 A / m 2 Under this condition, electrolysis was carried out for 3 hours to obtain a high-purity copper deposit at the cathode;

[0055] (4) Post-treatment: Finally, the copper deposit is washed and dried to obtain recovered copper.

[0056] Example 2

[0057] (1) Crushing and sorting: The waste circuit boards to be recycled are mechanically crushed, and after crushing, the metals and non-metals are separated by vibration screening and air flow sorting to obtain enriched metal particles:

[0058] (2) Preleaching: Mix the above metal particles with a dilute hydrochloric acid solution with a concentration of 0.2 mol / L, and leach at a temperature of 50° C. for 1.5 hours to obtain preleaching residue and preleaching liquid;

[0059] (3) Electrolytic deposition: ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:3, wherein the concentration of ammonium chloride was 0.05 mol / L and the concentration of ammonia water was 0.1 mol / L to obtain an electrolyte. The temperature of the electrolyte was controlled at 32°C and the current density was 32 A / m 2Under this condition, electrolysis was carried out for 4 hours, and a high-purity copper deposit was obtained at the cathode;

[0060] (4) Post-treatment: Finally, the copper deposit is washed and dried to obtain recovered copper.

[0061] Example 3

[0062] (1) Crushing and sorting: The waste circuit boards to be recycled are mechanically crushed, and after crushing, the metals and non-metals are separated by vibration screening and air flow sorting to obtain enriched metal particles:

[0063] (2) Preleaching: Mix the above metal particles with a dilute hydrochloric acid solution with a concentration of 0.5 mol / L, and leach at a temperature of 60° C. for 2 hours to obtain preleaching residue and preleaching liquid;

[0064] (3) Electrolytic deposition: ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:3, wherein the concentration of ammonium chloride was 0.05 mol / L and the concentration of ammonia water was 0.1 mol / L to obtain an electrolyte. The temperature of the electrolyte was controlled at 35°C and the current density was 35 A / m 2 Under this condition, electrolysis was carried out for 4 hours, and a high-purity copper deposit was obtained at the cathode;

[0065] (4) Post-treatment: Finally, the copper deposit is washed and dried to obtain recovered copper.

[0066] Example 4

[0067] (1) Crushing and sorting: The waste circuit boards to be recycled are mechanically crushed, and after crushing, the metals and non-metals are separated by vibration screening and air flow sorting to obtain enriched metal particles:

[0068] (2) Preleaching: mixing the above metal particles with a dilute hydrochloric acid solution with a concentration of 0.2 mol / L, and leaching at a temperature of 60° C. for 2 hours to obtain preleaching residue and preleaching liquid;

[0069] (3) Electrolytic deposition: ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:3, wherein the concentration of ammonium chloride was 0.05 mol / L and the concentration of ammonia water was 0.1 mol / L to obtain an electrolyte. The temperature of the electrolyte was controlled at 35°C and the current density was 32 A / m 2 Under this condition, electrolysis was carried out for 5 hours, and a high-purity copper deposit was obtained at the cathode;

[0070] (4) Post-treatment: Finally, the copper deposit is washed and dried to obtain recovered copper.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering copper from waste circuits, characterized in that: The following steps are involved: (1) Crushing and sorting: Mechanically crushing and sorting the waste circuit boards to obtain copper-enriched metal particles; (2) Preleaching: mixing the metal particles with a dilute sulfuric acid solution to perform a preleaching reaction to obtain preleaching residue and preleaching liquid; (3) Electrolytic deposition: using the pre-leaching solution as an electrolyte to perform electrolytic deposition to obtain a high-purity copper deposit; (4) Post-treatment: washing and drying the copper deposit to obtain recovered copper.

2. The method for recovering copper from waste circuits according to claim 1, characterized in that: The sorting method is one or more of vibration screen sorting, air flow sorting or electrostatic sorting.

3. The method for recovering copper from waste circuits according to claim 1, characterized in that: The concentration of the dilute sulfuric acid solution is 0.01-0.5 mol / L.

4. The method for recovering copper from waste circuits according to claim 1, characterized in that: The pre-leaching temperature is 40-60° C. and the pre-leaching time is 1-2 hours.

5. The method for recovering copper from waste circuits according to claim 1, characterized in that: Ammonium chloride and ammonia water are also added to the electrolyte.

6. The method for recovering copper from waste circuits according to claim 5, characterized in that: The concentration of the ammonium chloride is 0.01-0.1 mol / L.

7. The method for recovering copper from waste circuits according to claim 5, characterized in that: The concentration of the ammonia water is 0.01-0.2 mol / L.

8. The method for recovering copper from waste circuits according to claim 5, characterized in that: The mass ratio of the ammonium chloride, ammonia water and pre-leaching solution is 1:1:2-3.

9. The method for recovering copper from waste circuits according to claim 1, characterized in that: The current density of the electrolytic deposition is 30-35A / m 2 , the electrolysis time is 3 to 5 hours.

10. The method for recovering copper from waste circuits according to claim 1, characterized in that: The temperature of the electrolyte is 30-35°C.