A method for recovering copper from waste circuits

Abstract

This invention provides a method for recovering copper from waste circuit boards, belonging to the field of waste circuit board recycling technology. The method for recovering copper from waste circuit boards according to this invention includes the following steps: (1) Crushing and sorting: mechanically crushing and sorting the waste circuit boards to obtain copper-enriched metal particles; (2) Pre-leaching: mixing the metal particles with a dilute sulfuric acid solution to perform a pre-leaching reaction, obtaining pre-leaching residue and pre-leaching solution; (3) Electrolytic deposition: using the pre-leaching solution as an electrolyte for electrolytic deposition to obtain high-purity copper deposits; (4) Post-treatment: washing and drying the copper deposits to obtain recovered copper. The entire recycling process of the technical solution described in this invention does not generate harmful gases or wastewater, resulting in minimal environmental pollution. Furthermore, this invention allows for copper leaching and electrodeposition within the same device, shortening the process flow and reducing energy consumption.

Description

Technical Field

[0001] This invention relates to the field of waste circuit board recycling technology, and in particular to a method for recovering copper from waste circuit boards. Background Technology

[0002] With the rapid development of electronic technology, the pace of electronic product upgrades is accelerating. This results in a large amount of waste circuit boards, which not only contain toxic and harmful substances such as organic plastics and polybrominated biphenyls (PBBBs), but are also rich in precious metals such as copper, aluminum, gold, and silver. Improper handling will cause serious environmental pollution 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 soil, water sources, and air. Professional recycling can effectively prevent these harmful substances from leaking into the natural environment, protecting ecological safety. At the same time, the waste gas and wastewater generated during the recycling process undergo strict treatment to meet emission standards, ensuring the green and environmentally friendly nature of the entire recycling chain.

[0003] Metal resources in waste circuit boards have high recycling value. Through scientific recycling processes, precious metals and non-metallic components can be extracted from the circuit boards. After purification and processing, these resources can be reused in the manufacture of electronic products or other industrial fields, greatly reducing the need for primary mineral mining. This aligns with the concept of a circular economy, applying a closed-loop economic model of "resources-products-recycled resources" to electronic waste treatment, which helps achieve sustainable resource utilization.

[0004] Copper is an important metallic resource with wide applications in electronics, electrical engineering, construction, and transportation. With rapid global economic development, the demand for copper continues to grow, while its primary mineral resources are increasingly depleted. Waste circuit boards contain a large amount of copper, and recycling them can effectively extract this copper resource, alleviating resource shortages. At the same time, copper recycling can reduce the pressure on primary mineral resources, decrease energy consumption, and reduce environmental pollution. With the rapid development of the electronics industry, the production of circuit boards is increasing year by year. Copper, as an important component of circuit boards, has excellent electrical and thermal conductivity and is widely used in various industries. Therefore, recycling copper from waste circuit boards has become an important research topic.

[0005] Circuit boards are generally composed of a fiberglass cloth substrate and copper foil. The fiberglass cloth substrate and copper foil are tightly bonded together, making separation difficult. Currently, physical and chemical methods are mainly used to recover copper. Physical methods utilize the differences in density and magnetism of different substances after the waste circuit boards are crushed, employing gases, fluids, gravity, and magnetism to achieve separation. However, this method can only recover 70-80% of the metal, failing to completely solve the problem of separating metals from non-metals. Furthermore, the crushing process renders valuable fiberglass unusable waste and complicates subsequent metal and non-metal processing. Chemical methods use strong acids and other hydrometallurgical processes to separate and extract metallic copper, but this generates toxic wastewater, which leads to environmental pollution.

[0006] Therefore, providing a method for recovering copper from waste circuits with high recovery rate and low environmental pollution is of great practical significance. Summary of the Invention

[0007] The purpose of this invention is to provide a method for recovering copper from waste circuit boards, aiming to solve the technical problems of low precious metal recovery rate and environmental harm caused by waste circuit boards in the prior art.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

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

[0010] (1) Crushing and sorting: The waste circuit boards are mechanically crushed and sorted to obtain copper-enriched metal particles;

[0011] (2) Pre-leaching: The metal particles are mixed with dilute sulfuric acid solution to carry out a pre-leaching reaction, and pre-leaching residue and pre-leaching solution are obtained;

[0012] (3) Electrolytic deposition: The pre-leaching solution is used as the electrolyte for electrolytic deposition to obtain high-purity copper deposits;

[0013] (4) Post-processing: The copper deposit is washed and dried to obtain recovered copper.

[0014] Furthermore, the sorting method is one or more of vibrating screen sorting, airflow 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-immersion temperature is 40–60°C, and the time is 1–2 hours.

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

[0018] Furthermore, the mass ratio of 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 30–35 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 described in this invention does not produce harmful gases and wastewater, and has minimal environmental pollution;

[0025] (2) The present invention uses acid solution for leaching, which results in high copper leaching and recovery rates during electrolytic deposition. Furthermore, the present invention can perform copper leaching and electrodeposition in the same device, shortening the process flow and reducing energy consumption.

[0026] (3) The method described in this invention is simple, easy to operate, suitable for large-scale industrial production, and has good economic benefits. Detailed Implementation

[0027] Metal resources in waste circuit boards have high recycling value. Through scientific recycling processes, precious metals and non-metallic components can be extracted from the circuit boards. After purification and processing, these resources can be reused in the manufacture of electronic products or other industrial fields, greatly reducing the need for primary mineral mining. This aligns with the concept of a circular economy, applying a closed-loop economic model of "resources-products-recycled resources" to electronic waste treatment, which helps achieve sustainable resource utilization.

[0028] Copper is an important metallic resource with wide applications in electronics, electrical engineering, construction, and transportation. With rapid global economic development, the demand for copper continues to grow, while its primary mineral resources are increasingly depleted. Waste circuit boards contain a large amount of copper, and recycling them can effectively extract this copper resource, alleviating resource shortages. At the same time, copper recycling can reduce the pressure on primary mineral resources, decrease energy consumption, and reduce environmental pollution. With the rapid development of the electronics industry, the production of circuit boards is increasing year by year. Copper, as an important component of circuit boards, has excellent electrical and thermal conductivity and is widely used in various industries. Therefore, recycling copper from waste circuit boards has become an important research topic.

[0029] Circuit boards are generally composed of a fiberglass cloth substrate and copper foil. The fiberglass cloth substrate and copper foil are tightly bonded together, making separation difficult. Currently, physical and chemical methods are mainly used to recover copper. Physical methods utilize the differences in density and magnetism of different substances after the waste circuit boards are crushed, employing gases, fluids, gravity, and magnetism to achieve separation. However, this method can only recover 70-80% of the metal, failing to completely solve the problem of separating metals from non-metals. Furthermore, the crushing process renders valuable fiberglass unusable waste and complicates subsequent metal and non-metal processing. Chemical methods use strong acids and other hydrometallurgical processes to separate and extract metallic copper, but this generates toxic wastewater, which leads to environmental pollution.

[0030] Therefore, providing a method for recovering copper from waste circuits with high recovery rate and low environmental pollution is of great practical significance.

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

[0032] (1) Crushing and sorting: The waste circuit boards are mechanically crushed and sorted to obtain copper-enriched metal particles;

[0033] (2) Pre-leaching: The metal particles are mixed with dilute sulfuric acid solution to carry out a pre-leaching reaction, and pre-leaching residue and pre-leaching solution are obtained;

[0034] (3) Electrolytic deposition: The pre-leaching solution is used as the electrolyte for electrolytic deposition to obtain high-purity copper deposits;

[0035] (4) Post-processing: The copper deposit is washed and dried to obtain recovered copper.

[0036] In this invention, the sorting method is one or more of vibrating screen sorting, airflow sorting, or electrostatic sorting.

[0037] This invention first mechanically crushes waste circuit boards to facilitate soaking treatment. The size of the crushed waste circuit boards is not specifically limited, allowing for practical operation by those skilled in the art. Afterward, the boards are sorted, and multiple sorting methods can be used in combination or a single sorting method can be used. The combination of sorting methods is not specifically limited and can be adjusted according to actual application.

[0038] In this 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] This invention uses an acid solution for leaching, resulting in a high copper leaching and recovery rate during electrolytic deposition. Furthermore, this invention allows for copper leaching and electrodeposition within the same device, shortening the process flow, reducing energy consumption, and contributing to improved copper recovery.

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

[0041] This invention specifically limits the leaching temperature, which increases the solubility of waste circuit boards in the solution and further improves the leaching rate of copper from the waste circuit boards.

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

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

[0044] In this 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 this 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 this invention, the preferred current density for the electrolytic deposition is 30–35 A / m. 2 More preferably 30-32 A / m 2 The electrolysis time is preferably 3 to 5 hours, and more preferably 3 to 4 hours.

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

[0048] The entire recycling process of the technical solution described in this invention does not produce harmful gases or wastewater, resulting in minimal environmental pollution. Furthermore, the method described in this invention is simple, easy to operate, suitable for large-scale industrial production, and has good economic benefits, enabling rapid production recycling.

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

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

[0051] Example 1

[0052] (1) Crushing and sorting: The waste circuit boards to be recycled are mechanically crushed. After crushing, the metals and non-metals are separated by vibrating screen and airflow separation to obtain enriched metal particles:

[0053] (2) Pre-leaching: The above metal particles are mixed with a dilute hydrochloric acid solution with a concentration of 0.01 mol / L and leached at a temperature of 40°C for 1 hour to obtain pre-leaching residue and pre-leaching solution.

[0054] (3) Electrolytic deposition: Ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:2, with the concentration of ammonium chloride being 0.01 mol / L and the concentration of ammonia water being 0.01 mol / L, to obtain the electrolyte. The temperature of the electrolyte was controlled at 30℃ and the current density at 30 A / m. 2 Under these conditions, electrolysis for 3 hours yielded a high-purity copper deposit at the cathode.

[0055] (4) Post-processing: Finally, the obtained copper deposits are 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. After crushing, the metals and non-metals are separated by vibrating screen and airflow separation to obtain enriched metal particles:

[0058] (2) Pre-leaching: The above metal particles are mixed with a dilute hydrochloric acid solution with a concentration of 0.2 mol / L and leached at a temperature of 50°C for 1.5 hours to obtain pre-leaching residue and pre-leaching solution;

[0059] (3) Electrolytic deposition: Ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:3, with the concentration of ammonium chloride being 0.05 mol / L and the concentration of ammonia water being 0.1 mol / L, to obtain the electrolyte. The temperature of the electrolyte was controlled at 32℃ and the current density at 32 A / m. 2Under these conditions, electrolysis for 4 hours yielded a high-purity copper deposit at the cathode.

[0060] (4) Post-processing: Finally, the obtained copper deposits are 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. After crushing, the metals and non-metals are separated by vibrating screen and airflow separation to obtain enriched metal particles:

[0063] (2) Pre-leaching: The above metal particles are mixed with a dilute hydrochloric acid solution with a concentration of 0.5 mol / L and leached at a temperature of 60℃ for 2 hours to obtain pre-leaching residue and pre-leaching solution.

[0064] (3) Electrolytic deposition: Ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:3, with the concentration of ammonium chloride being 0.05 mol / L and the concentration of ammonia water being 0.1 mol / L, to obtain the electrolyte. The temperature of the electrolyte was controlled at 35℃ and the current density at 35 A / m. 2 Under these conditions, electrolysis for 4 hours yielded a high-purity copper deposit at the cathode.

[0065] (4) Post-processing: Finally, the obtained copper deposits are 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. After crushing, the metals and non-metals are separated by vibrating screen and airflow separation to obtain enriched metal particles:

[0068] (2) Pre-leaching: The above metal particles are mixed with a dilute hydrochloric acid solution with a concentration of 0.2 mol / L and leached at a temperature of 60℃ for 2 hours to obtain pre-leaching residue and pre-leaching solution;

[0069] (3) Electrolytic deposition: Ammonium chloride: ammonia water: pre-leaching solution were mixed in a mass ratio of 1:1:3, with the concentration of ammonium chloride being 0.05 mol / L and the concentration of ammonia water being 0.1 mol / L, to obtain the electrolyte. The temperature of the electrolyte was controlled at 35℃ and the current density at 32 A / m. 2 Under these conditions, electrolysis for 5 hours yielded a high-purity copper deposit at the cathode.

[0070] (4) Post-processing: Finally, the obtained copper deposits are washed and dried to obtain recovered copper.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering copper from waste circuits, characterized in that, Includes the following steps: (1) Crushing and sorting: The waste circuit boards are mechanically crushed and sorted to obtain copper-enriched metal particles; (2) Pre-leaching: The metal particles are mixed with dilute sulfuric acid solution to carry out a pre-leaching reaction, and pre-leaching residue and pre-leaching solution are obtained; (3) Electrolytic deposition: The pre-leaching solution is used as the electrolyte for electrolytic deposition to obtain high-purity copper deposits; (4) Post-processing: The copper deposit is washed and dried to obtain recovered copper; The concentration of the dilute sulfuric acid solution is 0.01–0.5 mol / L; Ammonium chloride and ammonia water were also added to the electrolyte; The concentration of the ammonium chloride is 0.01–0.1 mol / L; The concentration of the ammonia solution is 0.01–0.2 mol / L; The mass ratio of ammonium chloride, ammonia water, and pre-leaching solution is 1:1:2-3.

2. The method for recovering copper from waste circuits according to claim 1, characterized in that, The sorting method is one or more of the following: vibrating screen sorting, airflow sorting, or electrostatic sorting.

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

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

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