Method for efficiently stripping gold-plated layer of waste circuit board

Abstract

The invention relates to a method for efficiently stripping a gold-plated layer of a waste circuit board, which comprises the following steps: placing the waste circuit board in an acidic degolding solution containing Fe < 3 + >, and then introducing oxygen and / or air to carry out catalytic oxidation reaction to obtain a crude gold foil, a solution containing copper, nickel and iron and a degolding substrate; according to the method, the gold-plated layer of the waste circuit board can be preferentially and efficiently separated, the degolding solution is recycled, and the use of reagents is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable resource processing, and more specifically, to a method for efficiently stripping the gold plating layer from waste printed circuit boards. Background Art

[0002] The methods for selectively extracting gold from waste printed circuit boards can be classified into (1) dissolution method: using the complexation reaction between a solvent and gold to selectively leach the gold plating layer of waste printed circuit boards; (2) stripping method: using the difference in the electrode potentials of noble metal layers and base metals in the same medium system to slightly dissolve base metal coatings such as copper and nickel, while gold does not participate in the leaching reaction and falls off from the surface of the circuit board, thereby achieving the selective stripping of gold. However, due to environmental protection pressure, the dissolution method has been gradually phased out, and the environmentally friendly stripping method has become a research hotspot in recent years. Patent CN200710020408.5 discloses a method for recovering gold and copper from waste gold-plated printed circuit boards, using hydrogen peroxide and sulfuric acid as reaction reagents to recover gold and copper from waste gold-plated printed circuit boards; Patent Application CN202310338603.1 discloses a green and efficient stripping method for gold plating on the surface of circuit board scraps, using persulfate and strong oxidants to strip the gold plating layer; Patent Application CN202010058345.8 discloses a wet method for harmlessly extracting heavy metals from waste mobile phone circuit boards, using sulfuric acid, sodium chlorate, and hydrogen peroxide to strip the gold plating layer. However, the above methods have a large consumption of oxidants and high production costs.

[0003] Therefore, there is an urgent need to develop a new process for stripping the gold plating layer from waste printed circuit boards to reduce its production cost. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for efficiently stripping the gold plating layer from waste printed circuit boards. The method directly places the waste printed circuit boards in an acidic solution containing Fe 3+ and then introduces oxygen and / or air for reaction, which can achieve the preferential and efficient detachment of the gold plating layer from the waste printed circuit boards, and the gold stripping solution is recycled, greatly reducing the use of reagents.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for efficiently stripping the gold plating layer from waste printed circuit boards, comprising the following steps:

[0007] Place the waste printed circuit boards in an acidic gold stripping solution containing Fe 3+ and then introduce oxygen and / or air for catalytic oxidation reaction to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold-stripped substrate.

[0008] In some embodiments, the reaction temperature is 20 - 100 °C; preferably, it is 70 - 100 °C.

[0009] In some embodiments, the mass ratio of Fe in the gold stripping solution 3+ to the waste printed circuit board is 0.01 - 1:1.

[0010] In some embodiments, the concentration of H in the gold stripping solution + is 1 - 10 mol / L.

[0011] In some embodiments, the flow rate of the oxygen and / or air is 1 - 10 L / min.

[0012] In some embodiments, the liquid - solid ratio of the gold stripping solution to the waste printed circuit board is 1 - 10 mL:1 g.

[0013] In some embodiments, the reaction time is 10 - 100 min.

[0014] In some embodiments, the preparation of the gold stripping solution includes the step of dissolving a ferric compound in an acid solution.

[0015] In some embodiments, the ferric compound includes ferric salts and / or ferric oxides; the ferric compound includes, but is not limited to, ferric sulfate, ferric chloride, ferric nitrate, iron(III) oxide; preferably, it is ferric sulfate.

[0016] In some embodiments, the acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid; preferably, it is sulfuric acid.

[0017] In some embodiments, the method includes the following steps:

[0018] Place the waste printed circuit board in an acidic gold stripping solution containing Fe 3+ , then introduce a gas containing oxygen, and carry out a catalytic oxidation reaction under ultrasonic assistance conditions to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold - stripped substrate.

[0019] In some embodiments, the ultrasonic power is 400 - 900 W.

[0020] The reaction principle of the solution of the present invention is as follows:

[0021] Cu + 2Fe 3+ = Cu 2+ + 2Fe 2+

[0022] Ni + 2Fe 3+ = Ni 2+ + 2Fe 2+

[0023] Fe 2+ + O 2 + 4H+ = Fe 3+ + 2H 2 O

[0024] In an acidic solution, Fe 3+ undergoes a redox reaction with copper and nickel on the waste circuit board to generate Cu 2+ , Ni 2+ and Fe 2 + . By introducing oxygen and / or air into the acidic solution, Fe 2+ is easily oxidized to form Fe 3+ . The generated Fe 3+ reacts with copper and nickel again to achieve efficient stripping of the gold plating layer on the waste circuit board.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The present invention uses Fe 3+ as a medium, and oxygen / air oxidizes Fe 2+ in the solution to promote the regeneration of Fe 3+ . It can efficiently strip the gold plating layer on the waste circuit board, effectively solve the problems that the gold plating layer cannot be stripped directly using oxygen / air and the large consumption of the solution in the existing stripping method, greatly reduce the consumption of the gold stripping solution, reduce the process cost at the same time, achieve low-cost priority stripping of the gold plating layer on the waste circuit board, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the process flow chart of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art belonging to the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] Example 1

[0031] As Figure 1 shown, a method for efficiently stripping the gold plating layer on a waste circuit board includes the following steps:

[0032] Place the waste circuit board in a solution containing Fe 3+In an acidic solution, oxygen is introduced, and a catalytic oxidation reaction is carried out under ultrasonic intensification to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold-depleted substrate; among them, the solution containing Fe 3+ The acidic solution is prepared by dissolving ferric sulfate in sulfuric acid solution. The concentration of the sulfuric acid solution is 3 mol / L, and the mass ratio of ferric sulfate to the waste printed circuit board is 1 g:1 g; the oxygen flow rate is 1 L / min, the liquid-solid ratio of the acidic solution to the waste printed circuit board is 1 mL:1 g, the ultrasonic power is 500 W, the reaction temperature is 90 °C, and the reaction time is 60 min.

[0033] After the reaction, the stripping rate of Au is 95.94%.

[0034] Example 2

[0035] As Figure 1 shown, a method for efficiently stripping the gold plating layer of waste printed circuit boards includes the following steps:

[0036] Place the waste printed circuit board in an acidic solution containing Fe 3+ and introduce oxygen, and carry out a catalytic oxidation reaction under ultrasonic intensification to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold-depleted substrate; the acidic solution containing Fe 3+ is prepared by dissolving ferric sulfate in sulfuric acid solution. The concentration of the sulfuric acid solution is 3 mol / L, and the mass ratio of ferric sulfate to the waste printed circuit board is 0.1 g:1 g; the oxygen flow rate is 1 L / min; the liquid-solid ratio of the acidic solution to the waste printed circuit board is 1 mL:1 g, the ultrasonic power is 500 W, the reaction temperature is 90 °C, and the reaction time is 60 min.

[0037] After the reaction, the stripping rate of Au is 91.67%.

[0038] Example 3

[0039] A method for efficiently stripping the gold plating layer of waste printed circuit boards includes the following steps:

[0040] As Figure 1 shown, place the waste printed circuit board in an acidic solution containing Fe 3+ and introduce air, and carry out a catalytic oxidation reaction under ultrasonic intensification to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold-depleted substrate; among them, the acidic solution containing Fe 3+ is prepared by dissolving ferric sulfate in sulfuric acid solution. The concentration of the sulfuric acid solution is 3 mol / L, and the mass ratio of ferric sulfate to the waste printed circuit board is 1 g:1 g; the air flow rate is 10 L / min, the liquid-solid ratio of the acidic solution to the waste printed circuit board is 1 mL:1 g, the ultrasonic power is 500 W, the reaction temperature is 90 °C, and the reaction time is 60 min.

[0041] After the reaction, the stripping rate of Au is 93.79%.

[0042] Comparative Example 1

[0043] A method for stripping the gold plating layer of waste printed circuit boards includes the following steps:

[0044] Place the waste printed circuit board in an acidic solution, introduce oxygen, and carry out a catalytic oxidation reaction under ultrasonic intensification to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold-stripped substrate; wherein, the oxygen flow rate is 10 L / min, the acidic solution is a 3 mol / L sulfuric acid solution, the liquid-solid ratio of the acidic solution to the waste printed circuit board is 1 mL:1 g, the ultrasonic power is 500 W, the reaction temperature is 90 °C, and the reaction time is 60 min.

[0045] After the reaction, the stripping rate of Au is 0.83%.

[0046] Comparative Example 2

[0047] A method for stripping the gold plating layer of waste printed circuit boards includes the following steps:

[0048] Place the waste printed circuit board in an acidic solution containing Fe 3+ and carry out a catalytic oxidation reaction under ultrasonic intensification to obtain crude gold foil, a solution containing copper, nickel, and iron, and a gold-stripped substrate. Among them, the acidic solution containing Fe 3+ is prepared by dissolving ferric sulfate in a sulfuric acid solution. The concentration of the sulfuric acid solution is 3 mol / L, the mass ratio of ferric sulfate to the waste printed circuit board is 1 g:1 g, the liquid-solid ratio of the acidic solution to the waste printed circuit board is 1 mL:1 g, the ultrasonic power is 500 W, the reaction temperature is 90 °C, and the reaction time is 60 min.

[0049] After the reaction, the stripping rate of Au is 36.08%.

[0050] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0051] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A method for efficiently stripping the gold-plated layer of waste circuit boards, characterized in that: The following steps are involved: Place the waste circuit boards in a Fe-containing 3+ The gold foil is prepared by mixing the gold foil with an acidic gold removal solution, and then introducing oxygen and / or air to carry out a catalytic oxidation reaction to obtain a rough gold foil, a copper-nickel-iron solution and a gold removal substrate.

2. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 1, characterized in that: The reaction temperature is 20-100°C.

3. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 1, characterized in that: The degold solution contains Fe 3+ The mass ratio of waste circuit boards is 0.01-1:

1.

4. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 1, characterized in that: The degold solution contains H + The concentration is 1-10mol / L.

5. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 1, characterized in that: The flow rate of the oxygen and / or air is 1-10 L / min.

6. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 1, characterized in that: The liquid-to-solid ratio of the gold removal solution to the waste circuit board is 1-10 mL:1 g.

7. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 1, characterized in that: The preparation of the gold removal solution comprises the step of dissolving a trivalent iron compound in an acid solution.

8. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 7, characterized in that: The ferric iron compound includes ferric iron salt and / or ferric iron oxide; and / or the acid solution includes at least one of hydrochloric acid, sulfuric acid and nitric acid.

9. The method for efficiently stripping the gold-plated layer of waste circuit boards according to any one of claims 1 to 8, characterized in that: The following steps are involved: Place the waste circuit boards in a Fe-containing 3+ The gold foil is prepared by introducing an acidic gold removal solution, and then introducing an oxygen-containing gas to perform a catalytic oxidation reaction under ultrasonic-assisted conditions to obtain a rough gold foil, a copper-nickel-iron-containing solution and a gold removal substrate.

10. The method for efficiently stripping the gold-plated layer of waste circuit boards according to claim 9, characterized in that: The ultrasonic power is 400-900W.

Images