Method for removing paint film and recovering gold from gold-containing circuit board

Abstract

The invention discloses a method for recovering gold by removing a paint film of a gold-bearing circuit board, which comprises the following steps of: immersing the gold-bearing circuit board in a paint film removing agent, heating and stirring until the paint film of the gold-bearing circuit board completely falls off, taking a solid phase after solid-liquid separation, and cleaning with a cleaning agent to obtain the gold-bearing circuit board with the paint film removed, and recovering the gold from the gold-bearing circuit board with the paint film removed. In the process of removing the paint film of the gold-containing circuit board, the paint can be efficiently removed only by using a single alkali solution for simple treatment, and the gold recovery step is simplified. Meanwhile, according to the method, the dosage of chemicals is reduced, so that the treatment cost and the environmental protection pressure are reduced. In addition, the method can completely destroy the paint film, so that the gold is exposed on the surface layer of the circuit board, the electrolysis efficiency is improved in the gold electrolysis recovery process, and the gold recovery rate is improved. In addition, innocent treatment is carried out on the degolded circuit board residues through the cement kiln, fuel is saved, secondary pollution is avoided, and the double benefits of energy conservation and environmental protection are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic waste treatment, and in particular to a method for recovering gold by stripping a paint film on a gold-containing circuit board. Background Art

[0002] In the electronic product manufacturing industry, waste circuit boards are inevitable waste in the production process, and their treatment and disposal issues are becoming increasingly prominent. Waste circuit boards are not only classified as hazardous wastes because of the heavy metals (such as lead, cadmium, mercury, etc.) and organic pollutants they contain, which pose a potential threat to the production environment and human health, but also because they are rich in valuable precious metal resources such as copper, gold, silver, and palladium, which have attracted much attention. Especially in gold-containing circuit boards, gold is a high-value metal, and its effective recovery and resource utilization are of great significance to promoting the circular economy and saving resources.

[0003] However, the gold in the gold-containing circuit board is not completely exposed, but part of it is embedded in the interlayer between the circuit board and the paint film. This structure makes it difficult to directly recover the gold, because traditional recovery methods often have difficulty penetrating the paint film layer to achieve the purpose of effectively extracting gold. Therefore, before recovering gold, the discarded circuit board must first be pre-treated, that is, the paint film layer on the surface of the circuit board must be removed to expose the internal metal layer, thereby improving the gold recovery efficiency.

[0004] At present, there are some treatment methods for removing paint film from discarded circuit boards on the market, but these methods often have some problems, such as low treatment efficiency, large consumption of reagents, high treatment costs and possible secondary pollution. These problems not only limit the effective recovery of gold from discarded circuit boards, but may also cause further impacts on the environment and human health. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the present invention proposes a method for recovering gold by removing the paint film from a gold-containing circuit board, which can remove the paint film layer on the surface of the circuit board efficiently and at low cost, while reducing pollution to the environment and harm to the human body. In addition, the method can also improve the recovery rate of gold, reduce the amount of reagents used in the subsequent recovery process, and simplify the recovery steps, thereby achieving harmless treatment and resource utilization of discarded circuit boards.

[0006] A method for recovering gold by stripping paint film of a gold-containing circuit board comprises the following steps: immersing the gold-containing circuit board in a paint stripping agent, heating and stirring until the paint film of the gold-containing circuit board completely falls off, taking the solid phase after solid-liquid separation and washing it with a detergent to obtain a paint stripped gold-containing circuit board, and recovering gold from the paint stripped gold-containing circuit board.

[0007] Furthermore, the mass ratio of the gold-containing circuit board to the paint stripping agent is 1 to 3:1.

[0008] Furthermore, the heating temperature is 75-100°C.

[0009] Furthermore, the paint stripping agent is a 3-10% alkaline solution.

[0010] Furthermore, the alkali is sodium hydroxide or potassium hydroxide.

[0011] Furthermore, the paint film stripping treatment time is 10 to 30 minutes.

[0012] Furthermore, the cleaning agent is water.

[0013] Furthermore, the method for recovering gold from the gold-containing circuit board with a paint stripping film is an electrolytic method, and after recovering the gold, the gold-depleted circuit board residue is obtained.

[0014] Furthermore, the demetallized circuit board residues are treated harmlessly in a cement kiln as a regenerated fuel.

[0015] In summary, the present invention has the following beneficial effects:

[0016] First, in the process of removing the paint film of the gold-containing circuit board, the present invention does not require complex solvent combinations and processing conditions, and only needs to use a single low-concentration alkaline solution for heating and stirring to achieve an efficient paint film removal effect. This method not only simplifies the steps of gold recovery, but also reduces the amount of reagents used, and the reagents used are green and environmentally friendly. Therefore, the present invention effectively reduces the processing cost and environmental pressure in the process of recovering gold from gold-containing circuit boards.

[0017] Second, the surface paint film of the gold-containing circuit board treated by the method of the present invention can be completely destroyed, so that the wrapped gold is exposed on the surface of the circuit board. In the process of electrolytic recovery of gold, this treatment method greatly improves the electrolysis efficiency, thereby improving the gold recovery rate.

[0018] Third, the present invention uses a cement kiln to carry out harmless treatment of the circuit board residues after demetallization. This approach not only saves the fuel required by the cement kiln, but also avoids the secondary pollution that may be caused by the discarded circuit boards, thereby achieving the dual benefits of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 The present invention is a diagram of the operation steps of stripping the paint film of a gold-containing circuit board to recover gold. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] A method for recovering gold from paint film stripping of a gold-containing circuit board comprises the following steps: Figure 1 As shown: immersing the gold-containing circuit board in a paint film stripping agent, heating and stirring until the paint film of the gold-containing circuit board is completely removed, taking the solid phase after solid-liquid separation and washing it with a detergent to obtain a paint-stripped gold-containing circuit board, and recovering gold from the paint-stripped gold-containing circuit board.

[0023] This solution only requires adding a paint stripping agent and performing simple heating and stirring operations to achieve an efficient paint stripping effect. This method not only simplifies the steps of gold recovery, but also effectively reduces the processing cost of gold recovery from gold-containing circuit boards.

[0024] Furthermore, the mass ratio of the gold-containing circuit board to the paint stripping agent is 1 to 3:1.

[0025] In this scheme, the mass ratio of gold-containing circuit boards to paint stripping agents is optimized to 1 to 3:1. This means that only 1 / 3 of the mass of the circuit boards is needed to effectively remove the paint film, thereby reducing the amount of reagents used, and reducing the cost of raw materials and the cost of reagent recovery and processing.

[0026] Furthermore, the heating temperature is 75-100°C.

[0027] This solution optimizes the heating temperature of the paint film removal process of gold-containing circuit boards. Within this temperature range, the paint film of the circuit boards can be effectively removed within 10 to 30 minutes.

[0028] Furthermore, the paint stripping agent is a 3-10% alkaline solution.

[0029] This solution optimizes the selection and concentration of the paint film stripping agent. This solution uses a low-concentration alkali solution of 3 to 10% to achieve efficient paint film removal, and the lowest concentration can reach 3%, thereby reducing the use of alkali and recovery costs.

[0030] Furthermore, the alkali is sodium hydroxide or potassium hydroxide.

[0031] In the selection of alkali, this scheme adopts common raw materials such as sodium hydroxide or potassium hydroxide, which are not only low-cost but also highly environmentally friendly.

[0032] Furthermore, the paint film stripping treatment time is 10 to 30 minutes.

[0033] This solution optimizes the processing time for paint film removal, and the paint film can be effectively removed in as fast as 10 minutes, thereby improving processing efficiency and reducing costs.

[0034] Furthermore, the cleaning agent is water.

[0035] This solution also focuses on low cost and environmental protection in the selection of cleaning agents. The choice of clean water as a cleaning agent not only reduces the cost of raw materials, but also reflects a friendly attitude towards the environment.

[0036] Furthermore, the method for recovering gold from the gold-containing circuit board with a paint stripping film is an electrolytic method, and after recovering the gold, the gold-depleted circuit board residue is obtained.

[0037] This solution optimizes the gold recovery method to electrolysis. After the paint film stripping treatment, the surface paint film of the gold-containing circuit board has been completely removed, allowing the wrapped gold elements to be fully exposed. In the process of electrolytic gold recovery, this treatment method significantly improves the electrolysis efficiency, thereby achieving a significant increase in the gold recovery rate.

[0038] Furthermore, the demetallized circuit board residues are treated harmlessly in a cement kiln as a regenerated fuel.

[0039] This solution uses cement kilns for harmless treatment, which not only effectively saves the fuel costs required for cement kilns, but also successfully avoids the secondary pollution problem that may be caused by discarded circuit boards, thereby achieving the dual benefits of energy saving and environmental protection.

[0040] Example 1

[0041] 10 kg of waste gold-containing circuit board film was weighed and cut into segments, 10 kg of a paint stripping agent composed of a 3% sodium hydroxide aqueous solution was added thereto, the mixture was heated to 75° C., and stirred until the paint film completely fell off. After the paint was removed, the film was washed and separated with water to obtain a stripped gold-containing circuit board, from which gold was recovered by electrolysis, and the gold-removed circuit board residue obtained after the gold was recovered was treated harmlessly in a cement kiln as a regenerated fuel.

[0042] Example 2

[0043] 10 kg of waste gold-containing circuit board film was weighed and cut into segments, 5 kg of a paint stripping agent composed of a 7% potassium hydroxide aqueous solution was added thereto, the mixture was heated to 90° C., stirred until the paint film completely fell off, and washed and separated with water after the paint removal was completed. After separation, a stripped gold-containing circuit board was obtained, gold was recovered from it by electrolysis, and the gold-removed circuit board residue obtained after gold recovery was used as a regenerated fuel and subjected to harmless treatment in a cement kiln.

[0044] Example 3

[0045] 10 kg of waste gold-containing circuit board film was weighed and cut into segments, 3.3 kg of a paint stripping agent composed of a 10% sodium hydroxide aqueous solution was added thereto, the mixture was heated to 100° C., and stirred until the paint film completely fell off. After the paint removal was completed, the film was washed and separated with water to obtain a stripped gold-containing circuit board, and gold was recovered from it by electrolysis. The gold-removed circuit board residue obtained after gold recovery was used as a regenerated fuel and was harmlessly treated in a cement kiln.

[0046] Comparative Example 1

[0047] Blank control group: Weigh 10kg of waste gold-containing circuit board film and cut it into pieces, add 5kg of water, heat the mixture to 100℃, stir for 30min until the paint film completely falls off, wash and separate with water after paint removal, obtain the film-removed gold-containing circuit board after separation, recover gold from it by electrolysis, and the gold-removed circuit board residue obtained after gold recovery is treated harmlessly in a cement kiln as a recycled fuel.

[0048] The specific experimental conditions of each embodiment are shown in Table 1:

[0049] Table 1 List of experimental conditions corresponding to each embodiment

[0050] sample Quality Ratio temperature Paint stripping agent Alkali concentration% Example 1 1:1 75 Sodium hydroxide 3 Example 2 2:1 90 Potassium hydroxide 7 Example 3 3:1 100 Sodium hydroxide 10 Comparative Example 1 3:1 100 / 10

[0051] Test results and analysis

[0052] The present invention implements and strictly verifies the technical solutions proposed in Examples 1 to 3 in detail, and provides comparative examples. The complete fall-off time of the paint film and the gold recovery rate data of each example and comparative example are shown in Table 2:

[0053] Table 2 The paint film complete shedding time and gold recovery rate data of each embodiment and comparative example

[0054] sample Complete peeling time of paint film min Gold recovery % Example 1 30 96 Example 2 15 97 Example 3 10 99 Comparative Example 1 / 0

[0055] As shown in Table 2, Comparative Example 1 (i.e., only adding water in an amount equal to that of Example 3 as a substitute for the paint stripping agent) is consistent with Example 3 in all conditions except the paint stripping agent. Within the 30-minute treatment time, the paint film in Comparative Example 1 did not change at all; in contrast, Example 3 achieved complete removal of the paint film in just 10 minutes.

[0056] Specifically, in the paint film removal process of the gold-containing circuit board in Examples 1 to 3, we used a sodium hydroxide or potassium hydroxide solution with a concentration of 3% to 10% as a paint film stripping agent, and the addition amount accounted for 33% to 100% of the weight of the circuit board. Stirring treatment was carried out under temperature conditions of 75°C to 100°C, and all three embodiments successfully achieved complete and effective shedding of the paint film of the gold-containing circuit board, and the treatment time was between 10 and 30 minutes. In particular, in Example 3, we used a 10% concentration of sodium hydroxide solution and heated it at 100°C. At this time, the paint film fell off the fastest, only taking 10 minutes. This result shows the positive correlation between the paint film shedding efficiency and the paint film stripping agent concentration and the heat treatment temperature.

[0057] It can be seen that the treatment method provided by the present invention can efficiently and effectively remove the paint film on the surface of the gold-containing circuit board, laying the foundation for subsequent gold recovery work.

[0058] In terms of gold recovery efficiency, compared with the process without paint film removal in Comparative Example 1, the electrolytic gold recovery technology used in Examples 1 to 3 can achieve a high recovery rate of more than 95%, especially in Example 3, the recovery rate is as high as 99%. This remarkable achievement is mainly due to the successful removal of the paint film on the surface of the gold-containing circuit board in Examples 1 to 3, thereby fully exposing the metal surface. This step greatly reduces the physical obstacles in the electrolysis process, allowing the current to penetrate and act on the metal surface more smoothly, creating extremely favorable contact conditions for the subsequent electrolytic recovery process, thereby significantly improving the electrolysis efficiency.

[0059] At the same time, it is worth noting that the paint film often contains a certain amount of impurities such as non-metallic elements or organic matter. These impurities may interfere with the precipitation of gold ions during the electrolysis process, thereby affecting the purity and efficiency of the recovered gold. Through paint stripping, we can effectively remove these potential interference factors and ensure that the gold ions in the electrolytic recovery process can be precipitated more purely, thereby further improving the purity of the recovered gold and the overall recovery efficiency.

[0060] In summary, in the process of removing the paint film of the gold-containing circuit board, the present invention can efficiently remove the paint by simply treating with a single alkaline solution, thereby simplifying the steps of gold recovery. At the same time, the method reduces the amount of reagents used, thereby reducing the processing cost and environmental pressure. In addition, the method can completely destroy the paint film, expose the gold on the surface of the circuit board, and then improve the electrolysis efficiency and the gold recovery rate during the electrolytic recovery of gold. In addition, the present invention uses a cement kiln to perform harmless treatment on the gold-removed circuit board residues, which not only saves fuel but also avoids secondary pollution, achieving the dual benefits of energy saving and environmental protection.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering gold from paint stripping of a gold-containing circuit board, characterized in that: The following steps are involved: The gold-containing circuit board is immersed in a paint film stripping agent, heated and stirred until the paint film of the gold-containing circuit board is completely removed, the solid phase is taken out after solid-liquid separation and cleaned with a detergent to obtain a paint-removed gold-containing circuit board, and gold is recovered from the paint-removed gold-containing circuit board.

2. The method for recovering gold from paint stripping of a gold-containing circuit board according to claim 1, characterized in that: The mass ratio of the gold-containing circuit board to the paint stripping agent is 1 to 3:

1.

3. The method for recovering gold from paint film stripping of a gold-containing circuit board according to claim 1, characterized in that: The heating temperature is 75-100°C.

4. The method for recovering gold from paint stripping of a gold-containing circuit board according to claim 1, characterized in that: The paint film stripping agent is a 3-10% alkaline solution.

5. The method for recovering gold from paint film stripping of gold-containing circuit boards according to claim 4, characterized in that: The alkali is sodium hydroxide or potassium hydroxide.

6. The method for recovering gold from paint film stripping of a gold-containing circuit board according to claim 1, characterized in that: The paint film stripping treatment time is 10 to 30 minutes.

7. The method for recovering gold from paint stripping of a gold-containing circuit board according to claim 1, characterized in that: The cleaning agent is water.

8. The method for recovering gold from paint film stripping of gold-containing circuit boards according to claim 1, characterized in that: The method for recovering gold from the gold-containing circuit board with a paint stripping film is an electrolytic method, and after the gold is recovered, the gold-depleted circuit board residue is obtained.

9. The method for recovering gold from paint stripping of a gold-containing circuit board according to claim 8, characterized in that: The demetallized circuit board residues are treated harmlessly in a cement kiln.

Images