Method for recovering aluminum matrix from aluminum target containing indium tin solder

Abstract

The invention relates to a method for recovering an aluminum matrix from an aluminum target containing indium-tin solder, which comprises the following steps: placing the aluminum target containing indium-tin solder in an alkaline electrolyte, and carrying out electrolytic activation treatment on the aluminum target; and the aluminum target subjected to electrolytic activation treatment is placed in a stripping solution containing an organic phosphonic acid compound and H2O2, chemical stripping treatment is conducted on the aluminum target, the indium tin solder enters the stripping solution to be separated from the aluminum matrix, and the aluminum matrix is obtained through recycling. According to the method, the electrolytic activation treatment and the chemical stripping treatment are synergistic, so that the stripping efficiency of the indium-tin solder is greatly improved, and the damage rate of the aluminum matrix and the residual rate of the indium-tin solder are reduced.

Description

Technical Field

[0001] This application relates to the technical field of target recycling, and particularly to a method for recycling an aluminum matrix from an aluminum target containing indium-tin solder. Background Art

[0002] A sputtering residual target refers to the remaining part that has been sputtered to a certain extent in the sputtering coating process and can no longer meet the requirements of the normal sputtering process. Among them, a high-purity aluminum residual target (purity ≥ 99.999%) is the core consumable in the semiconductor sputtering process. There is an indium-tin solder layer with a thickness of 50 μm to 200 μm on its surface, that is, an aluminum target containing indium-tin solder. The indium-tin solder needs to be completely removed to meet the recycling standard of the same-grade aluminum material (residual amount ≤ 0.2 ppm). Traditional technologies mainly use chemical pickling, thermal shock, and mechanical grinding to remove the indium-tin solder layer. However, the chemical pickling method uses a mixed solution of nitric acid and hydrofluoric acid, resulting in an aluminum matrix corrosion damage rate > 1% and high heavy metal content in the waste liquid; the thermal shock method peels at a high temperature of > 300 °C, with high energy consumption and an indium-tin solder residual amount > 0.1%; the mechanical grinding method has low processing efficiency (< 5 kg / h), generates aluminum chip pollution, and a large loss in recovery rate. It is difficult for traditional technologies to balance the aluminum matrix damage rate and the indium-tin solder stripping efficiency. Summary of the Invention

[0003] Based on this, it is necessary to provide a method for recycling an aluminum matrix from an aluminum target containing indium-tin solder with a low aluminum matrix damage rate and high processing efficiency.

[0004] In one aspect of this application, a method for recycling an aluminum matrix from an aluminum target containing indium-tin solder is provided, including the following steps:

[0005] Placing the aluminum target containing indium-tin solder in an alkaline electrolyte, and performing electrolytic activation treatment on the aluminum target;

[0006] Placing the electrolytically activated aluminum target in a stripping solution containing an organic phosphonic acid compound and H 2 O 2 to perform chemical stripping treatment on the aluminum target, and recycling the aluminum matrix.

[0007] In the above method, an alkaline electrolyte is used to perform electrolytic activation treatment on the aluminum target containing indium-tin solder, which destroys the passivation layer on the surface of the indium-tin solder, forms a microporous structure on the indium-tin solder, increases its roughness, thereby providing excellent reaction conditions for subsequent chemical stripping treatment, enhancing the migration ability of indium ions and tin ions in the chemical stripping treatment, and reducing the stripping difficulty; in the chemical stripping treatment, a stripping solution containing an organic phosphonic acid compound and H 2 O 2 is used. The organic phosphonic acid compound can chelate indium ions and / or tin ions, and H 2 O 2The oxidation reaction inhibits metal deposition, thereby significantly improving the stripping efficiency of indium-tin solder, and the stripping solution has little corrosion to the aluminum substrate; in the above method, the electrolytic activation treatment and the chemical stripping treatment synergistically enhance the efficiency, greatly improving the stripping efficiency of indium-tin solder and reducing the damage rate of the aluminum substrate and the residual rate of indium-tin solder.

[0008] In some embodiments, in the stripping solution by mass percentage, the organophosphonic acid compound is 3% - 8%; and / or, in the stripping solution by mass percentage, the H 2 O 2 is added as hydrogen peroxide, and the content of the hydrogen peroxide is 2% - 5%.

[0009] Optionally, the stripping solution by mass percentage includes 3% - 8% of an organophosphonic acid compound, 2% - 5% of hydrogen peroxide, 0.5% - 1.5% of a pH regulator, and 85.5% - 94.5% of water.

[0010] In some embodiments, the organophosphonic acid compound includes at least one of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, and sodium ethylene diamine tetra (methylene phosphonic acid); and / or, the pH regulator is selected from at least one of sodium citrate, sodium dihydrogen phosphate, and tert-butyl diethylphosphonoacetate.

[0011] In some embodiments, the pH value of the stripping solution is 4 - 6.

[0012] In some embodiments, the temperature of the chemical stripping treatment is 40°C - 60°C; and / or, the time of the chemical stripping treatment is 8 min - 15 min.

[0013] In some embodiments, the alkaline electrolyte is 2% - 5% NaOH by mass concentration.

[0014] In some embodiments, the time of the electrolytic activation treatment is 2 min - 5 min; and / or, the voltage of the electrolytic activation treatment is 3 V - 5 V; and / or, the current density of the electrolytic activation treatment is 20 mA / cm 2 - 50 mA / cm 2 .

[0015] In some embodiments, ultrasonic treatment is performed during the chemical stripping treatment.

[0016] In some embodiments, the ultrasonic treatment uses pulsed ultrasound of 20 kHz - 40 kHz.

[0017] In some of these embodiments, the duty cycle of the ultrasonic treatment is 45% - 55%; and / or, the power density of the ultrasonic treatment is 0.8 W / cm 2 ~1.2 W / cm 2 . Specific embodiments

[0018] For ease of understanding the present application, the present application will be described more comprehensively below with reference to related embodiments. Preferred embodiments of the present application are given below. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0020] The aluminum matrix of the aluminum scrap target (aluminum target containing indium-tin solder) usually has a relatively high purity. For example, the purity of the aluminum matrix of the aluminum scrap target used for liquid crystal panels can reach more than 99.999%. The main factor affecting the purity of the aluminum scrap target is the indium-tin solder on the surface of the aluminum scrap target, and the indium-tin solder will reduce the overall purity and use value of the aluminum matrix. The current purification process for aluminum scrap targets either has low indium-tin solder stripping efficiency and high residue, or has a high aluminum matrix damage rate, and it is difficult to balance the stripping efficiency and the quality of the aluminum matrix.

[0021] Based on this, in the first aspect of the present application, an embodiment provides a method for recovering an aluminum matrix from an aluminum target containing indium-tin solder, including the following steps:

[0022] Placing the aluminum target containing indium-tin solder in an alkaline electrolyte and performing electrolytic activation treatment on the aluminum target;

[0023] Placing the electrolytically activated aluminum target in a stripping solution containing an organic phosphonic acid compound and H 2 O 2 and performing chemical stripping treatment on the aluminum target, so that the indium-tin solder enters the stripping solution and separates from the aluminum matrix, and the aluminum matrix is recovered.

[0024] In the above method, an alkaline electrolyte is used to perform electrolytic activation treatment on the aluminum target containing indium-tin solder, to destroy the passivation layer on the surface of the indium-tin solder, form a microporous structure on the indium-tin solder, increase its roughness, thereby providing excellent reaction conditions for subsequent chemical stripping treatment, enhancing the migration ability of indium ions and tin ions in the chemical stripping treatment, and reducing the stripping difficulty; in the chemical stripping treatment, a stripping solution containing an organic phosphonic acid compound and H2 O 2 stripping solution, the organophosphonic acid compound can chelate indium ions and / or tin ions, H 2 O 2 inhibits metal deposition through an oxidation reaction, thereby significantly improving the stripping efficiency of indium-tin solder, and the stripping solution has little corrosiveness to the aluminum substrate; in the above method, the electrolytic activation treatment and the chemical stripping treatment synergistically enhance the efficiency, greatly improving the stripping efficiency of indium-tin solder and reducing the aluminum substrate damage rate and the indium-tin solder residue rate.

[0025] The above method has a low treatment cost (which can be controlled within 1000 yuan / ton), significantly lower than the existing strong acid pickling process (above 3000 yuan / ton).

[0026] Understandably, the aluminum target containing indium-tin solder belongs to an aluminum residual target.

[0027] Understandably, the aluminum target containing indium-tin solder can be an aluminum target containing indium solder, an aluminum target containing tin solder, or an aluminum target containing indium solder and tin solder, or a mixed aluminum target of the foregoing aluminum targets.

[0028] In some embodiments, the alkaline electrolyte is NaOH with a mass concentration of 2% to 5%. Electrolysis with an electrolyte of 2% to 5% NaOH can break the passivation layer on the surface of indium-tin solder. The surface roughness of the indium-tin solder after electrolytic activation can be increased by more than 7 times, enhancing subsequent chemical penetration and enabling the chemical stripping efficiency to be increased by more than 3 times.

[0029] Understandably, the passivation layer on the surface of indium-tin solder is an oxide layer such as SnO and In 2 O 3 formed by the oxidation of indium-tin solder in contact with air. The process of electrolytic activation reaction is as follows: using a high-purity aluminum residual target with solder as the anode, NaOH in the alkaline electrolyte dissociates in water to generate Na + and OH - ions; at the anode (the surface of indium-tin solder), metals In and Sn are oxidized to form corresponding oxides; at the cathode, water molecules are reduced to generate hydrogen and OH - ions; during the application of voltage, the oxides on the anode surface (such as In 2 O 3 and SnO) undergo partial dissolution or local corrosion to form a microporous structure.

[0030] In some embodiments, the cathode of the electrolytic activation treatment is a nickel-based alloy, a titanium-based alloy, or stainless steel.

[0031] In some embodiments, the alkaline electrolyte is KOH with a mass concentration of 2% to 5%.

[0032] In some of these embodiments, the alkaline electrolyte is Na with a mass concentration of 5% - 10% 2 CO 3 .

[0033] In some of these embodiments, the time of the electrolytic activation treatment is 2 min to 5 min. This electrolytic activation treatment achieves a good balance between stripping indium-tin solder and protecting the aluminum substrate, further improving the stripping efficiency, reducing the aluminum substrate damage rate and the indium-tin solder residue rate.

[0034] As an example, the time of the electrolytic activation treatment can be 2 min, 2.5 min, 3 min, 3.5 min, 4.0 min, 4.5 min, and 5.0 min, or within the range formed by any two of the above point values as the end values. Preferably 2.5 min to 4.5 min.

[0035] In some of these embodiments, the voltage of the electrolytic activation treatment is 3 V to 5 V. At this voltage, the activation efficiency and the protection of the aluminum substrate are well balanced, which can not only efficiently remove the passivation layer on the surface of the indium-tin solder, but also prevent damage to the surface of the aluminum substrate.

[0036] As an example, the voltage of the electrolytic activation treatment can be 3.0 V, 3.5 V, 4.0 V, 4.5 V, and 5.0 V, or within the range formed by any two of the above point values as the end values. Preferably 3.5 V to 4.5 V.

[0037] In some of these embodiments, the current density of the electrolytic activation treatment is 20 mA / cm 2 ~50 mA / cm 2 .

[0038] As an example, the current density of the electrolytic activation treatment is 20 mA / cm 2 , 21 mA / cm 2 , 22 mA / cm 2 , 23 mA / cm 2 , 24 mA / cm 2 , 25 mA / cm 2 , 26 mA / cm 2 , 27 mA / cm 2 , 28 mA / cm 2 , 29 mA / cm 2 , 30 mA / cm 2 , 31 mA / cm 2 , 32 mA / cm 2 , 33 mA / cm 2 , 34 mA / cm 2 , 35 mA / cm 2 , 36 mA / cm2 , 37 mA / cm 2 , 38 mA / cm 2 , 39 mA / cm 2 , 40 mA / cm 2 , 41 mA / cm 2 , 42 mA / cm 2 , 43 mA / cm 2 , 44 mA / cm 2 , 45 mA / cm 2 , 46 mA / cm 2 , 47 mA / cm 2 , 48 mA / cm 2 , 49 mA / cm 2 and 50 mA / cm 2 , and it can also be within the range formed by any two of the above point values as the end values. Preferably 30 mA / cm 2 ~40 mA / cm 2 .

[0039] In some embodiments, in the stripping solution, by mass percentage, the organophosphonic acid compound is 3% - 8%.

[0040] In some embodiments, in the stripping solution, by mass percentage, the H 2 O 2 is added in the form of hydrogen peroxide, and the content of hydrogen peroxide is 2% - 5%.

[0041] In some embodiments, in the stripping solution, by mass percentage, the H 2 O 2 is added in the form of hydrogen peroxide, the mass concentration of hydrogen peroxide is 35%, and the content of hydrogen peroxide is 2% - 5%. The mass concentration of hydrogen peroxide (i.e., the mass concentration of H 2 O 2 in hydrogen peroxide) is not limited to 35%, and it only needs to meet the metering requirements of H 2 O 2 . Currently, the mass concentration of hydrogen peroxide in industry is usually 30% - 70%, all of which are applicable to this application.

[0042] In some embodiments, in the stripping solution, by mass percentage, the organophosphonic acid compound is 3% - 8%, and the H 2 O 2 is added in the form of hydrogen peroxide, the mass concentration of hydrogen peroxide is 35%, and the content of hydrogen peroxide is 2% - 5%.

[0043] In some of these embodiments, the stripping solution, by mass percentage, comprises 3% to 8% of an organic phosphonic acid compound, 2% to 5% of hydrogen peroxide (the mass concentration of hydrogen peroxide is 35%), 0.5% to 1.5% of a pH regulator, and 85.5% to 94.5% of water. The stripping solution of this formulation avoids the use of strong acids and strong bases, strips indium-tin solder thoroughly and efficiently, and compared with traditional strong acid stripping solutions, this stripping solution has no fluorine and nitrogen pollution, the COD value of the waste liquid is reduced by more than 98%, and the heavy metal ion concentration ≤ 10 ppm.

[0044] As an example, the mass percentage of the organic phosphonic acid compound can be 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, and 8%, and can also be within the range formed by any two of the above point values as the end values. The mass percentage of the organic phosphonic acid compound is preferably 5% to 7%.

[0045] As an example, the mass percentage of hydrogen peroxide can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%, and can also be within the range formed by any two of the above point values as the end values. The mass percentage of hydrogen peroxide is preferably 3% to 4%.

[0046] As an example, the mass percentage of the pH regulator can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%, and can also be within the range formed by any two of the above point values as the end values. The mass percentage of the pH regulator is preferably 0.8% to 1.2%.

[0047] In some of these embodiments, the stripping solution, by mass percentage, comprises 5% to 7% of an organic phosphonic acid compound, 3% to 4% of hydrogen peroxide (the mass concentration of hydrogen peroxide is 35%), 0.8% to 1.2% of a pH regulator, and 87.8% to 91.2% of water.

[0048] Furthermore, the organic phosphonic acid compound includes at least one of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, and sodium ethylene diamine tetra(methylene phosphonate). Preferably, the organic phosphonic acid compound includes hydroxyethylidene diphosphonic acid.

[0049] Furthermore, the pH regulator is selected from at least one of sodium citrate, sodium dihydrogen phosphate, and tert-butyl diethylphosphonoacetate. Preferably, the pH regulator is sodium citrate.

[0050] In some of these embodiments, the stripping solution, in terms of mass percentage, comprises 3% - 8% of hydroxyethylidene diphosphonic acid, 2% - 5% of hydrogen peroxide, 0.5% - 1.5% of sodium citrate, and 85.5% - 94.5% of water. In the stripping solution of this formulation, hydroxyethylidene diphosphonic acid can efficiently chelate indium ions and / or tin ions, and hydrogen peroxide can promptly inhibit metal deposition. The components synergistically enhance the efficiency, further improving the stripping efficiency of indium-tin solder and further reducing the damage rate of the aluminum substrate and the residual rate of indium-tin solder. Reaction kinetics experiments have demonstrated that the stripping rate of this stripping solution reaches over 2.5 μm / min at 60°C, which is over 200% higher than that of a single hydroxyethylidene diphosphonic acid.

[0051] In some of these embodiments, the stripping solution, in terms of mass percentage, comprises 5% - 7% of hydroxyethylidene diphosphonic acid, 3% - 4% of hydrogen peroxide, 0.8% - 1.2% of sodium citrate, and 87.8% - 91.2% of water. The stripping solution with this formulation further reduces the solder residue and the damage rate of the aluminum substrate.

[0052] In some of these embodiments, the pH value of the stripping solution is 4 - 6.

[0053] As an example, the pH value of the stripping solution can be 4.0, 4.5, 5.0, 5.5, and 6.0, or within the range formed by any two of the above point values as the end values.

[0054] In some of these embodiments, the temperature of the chemical stripping treatment is 40°C - 60°C. Preferably 50°C - 60°C.

[0055] In some of these embodiments, the conductivity of the stripping solution is 1800 μS / cm - 2300 μS / cm.

[0056] During the use of the stripping solution, the conductivity will decrease due to the consumption of effective components or the accumulation of pollutants. When the conductivity is lower than 5% of the process lower limit (<1710 μS / cm), adjust the temperature or replenish the stripping solution.

[0057] In some of these embodiments, the time of the chemical stripping treatment is 8 min - 15 min. Preferably 8 min - 10 min.

[0058] As an example, the time of the chemical stripping treatment can be 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min, or within the range formed by any two of the above point values as the end values.

[0059] In some of these embodiments, it further includes an ultrasonic treatment step: performing ultrasonic treatment during the chemical stripping treatment.

[0060] In some of these embodiments, the ultrasonic treatment uses pulsed ultrasound with a frequency of 20 kHz to 40 kHz. The pulsed ultrasound with a frequency of 20 kHz to 40 kHz generates a cavitation effect, forming a richer microporous structure in the indium-tin solder layer and further damaging the interfacial bonding force between the indium-tin solder and the aluminum substrate.

[0061] In some of these embodiments, the duty cycle of the ultrasonic treatment is 40% to 60%. At this duty cycle, cavitation damage can be reduced, the stripping efficiency can be further improved without causing damage to the aluminum substrate, and the protection of the aluminum substrate is better.

[0062] As an example, the duty cycle of the ultrasonic treatment is 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% and 60%, and it can also be within the range formed by any two of the above point values as the end values. The duty cycle of the ultrasonic treatment is preferably 45% to 55%. More preferably 50% to 55%.

[0063] In some of these embodiments, the power density of the ultrasonic treatment is 0.8 W / cm 2 ~1.2 W / cm 2 .

[0064] In some of these embodiments, the time of the ultrasonic treatment is 8 min to 15 min.

[0065] In some of these embodiments, the high-temperature gas generated during the electrolytic activation treatment is used for heating and temperature raising in the chemical stripping treatment. Using the high-temperature gas by-produced in the electrolytic activation treatment to heat the stripping solution can save more than 30% of energy compared with the traditional strong acid pickling process.

[0066] Further, the high-temperature gas generated during the electrolytic activation treatment includes but is not limited to hydrogen.

[0067] As an example, hydrogen can release a large amount of heat through direct combustion, and the released heat can be transferred to the chemical stripping treatment through a heat exchanger or a heat-conducting medium (such as steam or heat-conducting oil) to heat the reaction materials, thereby maximizing the recovery of heat and reducing energy loss.

[0068] In some of these embodiments, it further includes an indium-tin solder recovery step, and the stripping solution containing indium-tin solder is subjected to electrodialysis treatment using a cation exchange membrane to recover indium-tin solder.

[0069] In some of these embodiments, the high-temperature gas generated during the electrolytic activation treatment is used to heat up the chemical stripping treatment, and the stripping solution containing indium-tin solder is subjected to electrodialysis treatment using a cation exchange membrane to recover the indium-tin solder. The combination of hydrogen recovery for heat supply and electrodialysis for metal recovery achieves almost zero emissions except for a small amount of waste liquid.

[0070] The following are specific examples.

[0071] Example 1

[0072] In an electrolytic cell, NaOH with a mass concentration of 3% is used as the electrolyte. An aluminum target with an indium and tin solder layer having a thickness of 50 μm to 200 μm is placed in the electrolyte, and a voltage of 4 V is applied with a current density of 35 mA / cm 2 , and the aluminum target is subjected to electrolytic activation treatment for 3 minutes;

[0073] In a chemical stripping tank, the electrolytically activated aluminum target is placed in the stripping solution for chemical stripping treatment of the aluminum target. The heat energy of the hydrogen gas generated by the electrolytic activation treatment is used to heat the stripping solution to 50 °C, and 30 kHz pulsed ultrasonic treatment is carried out for 10 minutes during the chemical stripping treatment, so that the indium-tin solder enters the stripping solution and separates from the aluminum matrix, and the aluminum matrix is recovered; among them, the stripping solution, by mass percentage, includes 5% of hydroxyethylidene diphosphonic acid, 3% of hydrogen peroxide (the mass concentration of hydrogen peroxide is 35%), 1.2% of sodium citrate, and 90.8% of water; the pH value of the stripping solution is 4.5; the frequency of the pulsed ultrasonic wave is 30 kHz, and the duty cycle is 50%;

[0074] Among them, the hydrogen gas generated by the electrolytic activation treatment can be directly burned through a burner, releasing a large amount of heat, and the released heat can be transferred to the chemical stripping tank through a heat exchanger or a heat-conducting medium (such as steam or heat-conducting oil) to heat the reaction materials;

[0075] The stripping solution containing indium-tin solder is subjected to electrodialysis treatment using a cation exchange membrane to recover the indium-tin solder, and the stripping solution after the indium-tin solder is recovered is reused for chemical stripping treatment.

[0076] Example 2

[0077] Example 2 is basically the same as Example 1, the difference is that: the voltage of the electrolytic activation treatment is 5 V, and the time of the electrolytic activation treatment is 2 minutes; the stripping solution, by mass percentage, includes 8% of hydroxyethylidene diphosphonic acid, 5% of hydrogen peroxide, 0.8% of sodium citrate, and 86.2% of water; the temperature of the stripping solution is 60 °C; the pulsed ultrasonic treatment is 8 minutes.

[0078] Example 3

[0079] Example 3 is basically the same as Example 1, except that: the voltage for electrolytic activation treatment is 3V, and the time for electrolytic activation treatment is 5 min; the stripping solution, by mass percentage, includes 3% of hydroxyethylidene diphosphonic acid, 2% of hydrogen peroxide, 1% of sodium citrate, and 94% of water; the temperature of the stripping solution is 40°C; and pulsed ultrasonic treatment is performed for 15 min.

[0080] Example 4

[0081] Example 4 is basically the same as Example 1, except that: hydroxyethylidene diphosphonic acid is replaced with an equal mass of aminotrimethylenephosphonic acid.

[0082] Example 5

[0083] Example 5 is basically the same as Example 1, except that: the duty cycle of the pulsed ultrasonic is 60%.

[0084] Comparative Example 1

[0085] Comparative Example 1 is basically the same as Example 1, except that: the electrolytic activation treatment is omitted.

[0086] Comparative Example 2

[0087] For the traditional chemical pickling method, pickling is carried out using a mixed acid of nitric acid and hydrofluoric acid. The mass content of nitric acid in the mixed acid is 10%, and the mass content of hydrofluoric acid is 2%. It is soaked at 25°C for 30 min.

[0088] Comparative Example 3

[0089] Comparative Example 3 is basically the same as Example 1, except that: hydroxyethylidene diphosphonic acid is replaced with an equal mass of hydrogen peroxide.

[0090] Comparative Example 4

[0091] Comparative Example 4 is basically the same as Example 1, except that: hydrogen peroxide is replaced with an equal mass of hydroxyethylidene diphosphonic acid.

[0092] The aluminum substrates recovered from Examples 1 to 5 and Comparative Examples 1 to 4 were subjected to performance tests, and the test results are shown in Table 1 below.

[0093] Table 1

[0094]

[0095] As can be seen from Table 1 above, in Examples 1 to 5, the solder residue < 0.2 ppm, meeting the recovery index of 5N (99.999%) grade high-purity aluminum; the damage rate of the aluminum matrix ≤ 0.08%, indicating a high recovery rate of the residual target; compared with the traditional hot melting method, both the treatment efficiency and energy consumption have significant advantages; the COD value of the waste liquid < 130 mg / L, indicating good environmental protection effects. The solder residues in Comparative Examples 1 to 4 are too high, and the aluminum matrix in Comparative Examples 2 and 3 is damaged more severely. Thus, without the electrolytic activation treatment of this application or without the chemical stripping treatment using the specific stripping liquid in this application, the technical effects of this application cannot be achieved.

[0096] In addition, it is better to select hydroxyethylidene diphosphonic acid as the phosphonic acid compound in the stripping liquid. The following stripping liquid is used: the stripping liquid, calculated by mass percentage, includes 5% - 7% of an organic phosphonic acid compound, 3% - 4% of hydrogen peroxide (the mass concentration of hydrogen peroxide is 35%), 0.8% - 1.2% of a pH regulator, and 87.8% - 91.2% of water, and a lower aluminum matrix damage rate is obtained with low solder residue. When the duty cycle of the ultrasonic treatment is within the range of 45% - 55%, the aluminum matrix damage rate is lower.

[0097] 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 recorded in this specification.

[0098] The above-described embodiments merely represent several implementation manners of this application. The description is relatively specific and detailed, but it should not be construed as a limitation on 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 this application, several deformations and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of the patent of this application should be subject to the appended claims.

Claims

1. A method for recovering an aluminum matrix from an aluminum target containing indium tin solder, characterized in that: The following steps are involved: placing an aluminum target containing indium tin solder in an alkaline electrolyte and performing an electrolytic activation treatment on the aluminum target; The aluminum target after electrolytic activation treatment is placed in a stripping solution containing an organic phosphonic acid compound and H2O2, and the aluminum target is subjected to chemical stripping treatment to recover the aluminum matrix.

2. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to claim 1, characterized in that: The organic phosphonic acid compound is 3% to 8% by weight in the stripping solution; and / or, the H2O2 is added in the form of hydrogen peroxide, and the content of the hydrogen peroxide is 2% to 5% by weight in the stripping solution; Optionally, the stripping solution comprises, by mass percentage, 3% to 8% of an organic phosphonic acid compound, 2% to 5% of hydrogen peroxide, 0.5% to 1.5% of a pH regulator and 85.5% to 94.5% of water.

3. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to claim 2, characterized in that: The organic phosphonic acid compound includes at least one of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, diethylenetriamine penta (methylene phosphonic acid), and sodium ethylenediamine tetra (methylene phosphonic acid); and / or the pH regulator is selected from at least one of sodium citrate, sodium dihydrogen phosphate, and diethylphosphonoacetate.

4. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to claim 1, characterized in that: The pH value of the stripping solution is 4-6.

5. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to claim 1, characterized in that: The temperature of the chemical stripping treatment is 40° C. to 60° C.; and / or the time of the chemical stripping treatment is 8 min to 15 min.

6. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to any one of claims 1 to 5, characterized in that: The alkaline electrolyte is NaOH with a mass concentration of 2% to 5%.

7. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to any one of claims 1 to 5, characterized in that: The time of the electrolytic activation treatment is 2 min to 5 min; and / or, the voltage of the electrolytic activation treatment is 3 V to 5 V; and / or, the current density of the electrolytic activation treatment is 20 mA / cm 2 ~50mA / cm 2 .

8. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to any one of claims 1 to 5, characterized in that: Ultrasonic treatment was performed during the chemical peeling process.

9. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to claim 8, characterized in that: The ultrasonic treatment uses pulsed ultrasound of 20kHz to 40kHz.

10. The method for recovering an aluminum matrix from an aluminum target containing indium tin solder according to claim 8, characterized in that: The duty cycle of the ultrasonic treatment is 45% to 55%; and / or the power density of the ultrasonic treatment is 0.8 W / cm 2 ~1.2W / cm 2 .

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