A method for separating scrap aluminum alloys with different magnesium contents

Abstract

This invention discloses a method for separating scrap aluminum alloys with different magnesium contents. The method comprises the following steps: immersing the scrap aluminum alloys with different magnesium contents in a coloring solution for surface coloring; removing the scrap aluminum alloys with different magnesium contents from the coloring solution; and then separating the scrap aluminum alloys with different magnesium contents based on color difference. The coloring solution includes any one of copper sulfate solution, copper chloride solution, zinc sulfate solution, and zinc chloride solution. This invention proposes a scheme for separating scrap aluminum alloys with different magnesium contents, avoiding the need for large amounts of magnesium removal agents or pure aluminum, thus fully utilizing the advantages of preparing recycled aluminum from scrap aluminum alloys. The scheme of this invention is simple in process, uses readily available raw materials, is low in cost, and is easy to automate.

Description

Technical Field

[0001] This invention relates to a method for separating waste aluminum alloys with different magnesium contents, belonging to the field of recycled aluminum raw material sorting technology. Background Technology

[0002] Recycled aluminum is an aluminum alloy material produced from waste aluminum alloy products and aluminum materials through processes such as smelting and refining. Compared to primary aluminum (derived from bauxite), recycled aluminum has the following significant advantages: energy saving and environmental protection; the energy consumption of recycled aluminum is only about 5% of that of primary aluminum, reducing energy consumption by 95% and carbon emissions by more than 90%. The mechanical properties and corrosion resistance of recycled aluminum are comparable to those of primary aluminum, meeting the needs of the automotive, construction, and packaging industries, achieving closed-loop resource utilization. The production cost of recycled aluminum is 30%-50% lower than that of primary aluminum, and the production process is shorter, helping enterprises reduce costs and increase efficiency.

[0003] Currently, the main technologies for sorting scrap aluminum alloys are gravity flotation, magnetic separation, or X-ray separation. Sorting scrap aluminum alloys is a crucial step in recycling, directly affecting the purity and performance of the recycled aluminum. Based on sorting principles and techniques, scrap aluminum alloy sorting methods can be mainly classified into the following categories:

[0004] Physical separation methods include magnetic separation, eddy current separation, and gravity separation. Magnetic separation uses magnetic differences to separate ferrous impurities (such as screws and steel filings) from aluminum, and is suitable for preliminary iron removal. Eddy current separation is based on differences in conductivity; an alternating magnetic field induces eddy currents in non-ferrous metals (such as aluminum), which are then ejected and separated, making it suitable for separating mixed metal waste. Gravity separation utilizes density differences, using wind, water flow, or vibrating screens to separate aluminum from lightweight impurities such as plastics and rubber.

[0005] Chemical separation methods include flotation and smelting refining. Flotation uses chemical reagents to adjust the surface properties of aluminum and impurities, causing them to separate in bubbles; it is suitable for treating fine-particle aluminum slag. Smelting refining uses fluxes (such as salt solvents) in a high-temperature molten state to remove alumina and other non-metallic inclusions, improving the purity of the molten aluminum.

[0006] Intelligent sorting technologies include X-ray fluorescence (XRF) sorting, laser-induced breakdown spectroscopy (LIBS), and artificial intelligence (AI) sorting. XRF sorting uses X-rays to identify the alloy composition of aluminum, achieving high-precision sorting. LIBS utilizes laser analysis to determine the elemental composition of aluminum, suitable for the precise classification of high-end recycled aluminum. AI sorting combines machine vision and deep learning to automatically identify and sort different types and sizes of aluminum scrap, improving sorting efficiency and accuracy.

[0007] Manual sorting is suitable for small-scale recycling or pre-processing stages. It separates aluminum products by manual screening, tapping and other methods. It is low in cost but has limited efficiency.

[0008] Different sorting methods can be used individually or in combination, depending on the source of the scrap aluminum, the type of impurities, and the intended use of the recycled aluminum.

[0009] However, the sorting of magnesium-containing aluminum alloys remains a challenge in current recycled aluminum sorting technologies. Because magnesium and aluminum have similar specific gravities and adjacent atomic numbers, aluminum alloys with different magnesium contents have similar specific gravities, making separation difficult. Furthermore, aluminum and magnesium have similar physical and magnetic properties, making accurate sorting even under X-ray analysis. This necessitates magnesium removal when preparing recycled aluminum from high-magnesium-content scrap aluminum alloys. Magnesium removal requires large amounts of magnesium-removing agents, and the high temperature of the molten aluminum during this process leads to significant aluminum loss, resulting in very high costs. If pure aluminum is used for dilution due to the high magnesium content, the amount of new aluminum used will be extremely high, failing to fully realize the advantages of recycled aluminum. Therefore, finding a simple and efficient way to separate scrap aluminum alloys with different magnesium contents is crucial for fully leveraging the advantages of recycled aluminum. Summary of the Invention

[0010] To overcome the problems existing in the prior art, the present invention provides a method for separating scrap aluminum alloys with different magnesium contents, which is conducive to achieving the separation of scrap aluminum alloys with different magnesium contents in a simple, efficient and low-cost manner, and helps to give full play to the technical advantages of preparing recycled aluminum from scrap aluminum alloys. The specific technical solution is as follows.

[0011] A method for separating scrap aluminum alloys with different magnesium contents, characterized by comprising the following steps: immersing scrap aluminum alloys with different magnesium contents in a coloring solution for surface coloring, removing the scrap aluminum alloys with different magnesium contents from the coloring solution, and then separating the scrap aluminum alloys with different magnesium contents according to the color difference; wherein the coloring solution includes any one of copper sulfate solution, copper chloride solution, zinc sulfate solution, and zinc chloride solution.

[0012] Using the above technical solution, scrap aluminum alloys with different magnesium contents are immersed in a coloring solution for coloring. Magnesium in the scrap aluminum alloys has the strongest reducing properties, displacing copper and zinc ions from the solution. Due to the different magnesium contents, the scrap aluminum alloy blocks with different magnesium contents form different morphologies after dissolution, thus forming different color layers under ordinary and infrared light. High-Mg-content scrap aluminum alloys are darker in color, while low-Mg-content scrap aluminum alloys are lighter in color, allowing for the separation of scrap aluminum alloys with different magnesium contents based on color difference.

[0013] Further, the concentration of the copper sulfate solution, copper chloride solution, zinc sulfate solution, or zinc chloride solution is 0.001 mol / L to 0.1 mol / L. Preferably, the coloring solution is a 0.05 mol / L copper sulfate solution, or a 0.05 mol / L copper chloride solution, or a 0.001 mol / L zinc sulfate solution.

[0014] Furthermore, the soaking time is 5 min-600 min, and the soaking temperature is 0℃-40℃.

[0015] Furthermore, different magnesium content scrap aluminum alloys can be separated manually or using a camera based on color differences. Alternatively, image recognition technology combined with machine learning can be used to automatically separate different magnesium content scrap aluminum alloys based on color differences.

[0016] Furthermore, a bleaching solution is used to bleach the coloring layer of the waste aluminum alloy. This bleaching solution is either dilute hydrochloric acid or dilute sulfuric acid. For recycled aluminum where zinc content needs to be controlled, the zinc-containing coloring layer can be removed using dilute hydrochloric acid or dilute sulfuric acid. The colored waste aluminum alloy can be briefly immersed in the bleaching solution, or it can be rinsed with the bleaching solution. After bleaching, the waste aluminum alloy is fed into a smelting furnace for regenerative smelting. Simultaneously, the dilute zinc sulfate or dilute zinc chloride solution, after slag removal and purification, can be reused as a coloring solution, thus achieving the repeated recycling of zinc ions.

[0017] The present invention has the following beneficial effects.

[0018] 1. This invention innovatively proposes a scheme for separating waste aluminum alloys with different magnesium contents, avoiding the need to add large amounts of magnesium removal agents or pure aluminum, thereby giving full play to the advantages of preparing recycled aluminum from waste aluminum alloys.

[0019] 2. The present invention has a simple process, readily available raw materials, low cost, and is easy to automate sorting.

[0020] 3. In particular, when zinc chloride solution and zinc sulfate solution are used as coloring solutions, and dilute hydrochloric acid solution and dilute sulfuric acid solution are used as bleaching solutions, zinc ions can be recycled repeatedly, further reducing process costs. Attached Figure Description

[0021] Figure 1 These are near-infrared camera images of waste aluminum alloys with different magnesium contents after separation, as described in Example 1. Figure 1 (a) and Figure 1 (b) is a photograph of the Al-7Si-0.5Mg alloy. Figure 1 (c) and Figure 1 (d) is a photograph of the Al-7Si-0.25Mg alloy.

[0022] Figure 2 These are photographs taken with a regular camera of scrap aluminum alloys with different magnesium contents after separation, as shown in Example 1. Figure 2 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 2 (b) is a photograph of the Al-7Si-0.25Mg alloy.

[0023] Figure 3 These are photographs taken with a regular camera of waste aluminum alloys with different magnesium contents after separation, as shown in Example 2. Figure 3 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 3 (b) is a photograph of the Al-7Si-0.25Mg alloy.

[0024] Figure 4 These are photographs taken with a regular camera of waste aluminum alloys with different magnesium contents after separation, as shown in Example 3. Figure 4 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 4 (b) is a photograph of the Al-7Si-0.25Mg alloy.

[0025] Figure 5 These are near-infrared camera images of waste aluminum alloys with different magnesium contents after separation, as shown in Example 3. Figure 5 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 5 (b) is a photograph of the Al-7Si-0.25Mg alloy. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings.

[0027] Example 1

[0028] Taking waste aluminum-silicon-magnesium alloy as an example, the Al-7Si-0.25Mg alloy and Al-7Si-0.5Mg alloy were separated.

[0029] The specific steps are as follows:

[0030] Coloring was performed using CuSO4 solution (0.05 mol / L), with an immersion time of 45 min and a temperature of 25℃. After immersion, the high-Mg-content Al-7Si-0.5Mg alloy exhibited a dark brown color, while the low-Mg-content Al-7Si-0.25Mg alloy showed removable flocculent brown substances. After cleaning the surface, images were taken using a conventional camera and a near-infrared camera (Mideview MV-GEC130I short-wave infrared industrial camera), and the results are as follows. Figure 1 and Figure 2 As shown. Among them, Figure 1 (a) and Figure 1 (b) is a photograph of the Al-7Si-0.5Mg alloy. Figure 1 (c) and Figure 1 (d) is a photograph of the Al-7Si-0.25Mg alloy; Figure 2 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 2 (b) is a photograph of the Al-7Si-0.25Mg alloy.

[0031] Comparison shows that the high-Mg-content Al-7Si-0.5Mg alloy appears bright under a near-infrared camera. Figure 1 It appears brown under a regular camera ( ). Figure 2 Low-Mg content Al-7Si-0.25Mg alloys appear dark under near-infrared cameras. Figure 1 Under a regular camera, it appears as a metallic silver background with a discontinuous distribution of small amounts of brown copper. Figure 2 It can clearly distinguish alloys with different magnesium contents, and the composition can be controlled within the error range of the alloy grade.

[0032] For recycled aluminum where copper content needs to be controlled, a copper stripping solution can be used to remove the copper-containing color layer, reducing copper contamination of the molten aluminum. The copper stripping solution contains 0.5–3% copper stripping accelerator, 2–5% sodium dodecylbenzenesulfonate, 0.1–0.3% boric acid, 1–3% malic acid, 3–5% sodium bromate, 3–5% nitric acid, and the balance being water.

[0033] Example 2

[0034] ZnCl2 was used as the coloring solution for coloring and separation of Al-7Si-0.25Mg and Al-7Si-0.5Mg alloys. The specific operation is as follows:

[0035] The ZnCl2 solution concentration was 0.01 mol / L, the soaking time was 5 min, and the temperature was 20℃. After soaking, the high Mg content Al-7Si-0.5Mg alloy appeared dark black, while the low Mg content Al-7Si-0.25Mg alloy appeared gray. After cleaning the surfaces, photos were taken with a regular camera, and the results are as follows. Figure 3 As shown. Figure 3 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 3 (b) is a photograph of the Al-7Si-0.25Mg alloy.

[0036] For recycled aluminum where zinc content needs to be controlled, dilute hydrochloric acid solution can be used as a bleaching solution to remove the zinc-containing coloring layer. After bleaching, the waste aluminum alloy is put into a smelting furnace for regenerative smelting. At the same time, the dilute zinc chloride solution can be used again as a coloring solution after slag removal and purification, thus realizing the repeated recycling of zinc ions.

[0037] Example 3

[0038] ZnSO4 was used as the coloring solution for coloring and separation of Al-7Si-0.25Mg and Al-7Si-0.5Mg alloys. The specific operation is as follows:

[0039] The ZnSO4 solution concentration was 0.001 mol / L, the soaking time was 10 hours, and the temperature was 20℃. After soaking and cleaning the surface, photos were taken using a regular camera and a near-infrared camera (MaideVision MV-GEC130I short-wave infrared industrial camera). The results are as follows. Figure 4 and Figure 5 As shown. Among them, Figure 4 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 4 (b) is a photograph of the Al-7Si-0.25Mg alloy; Figure 5 (a) is a photograph of the Al-7Si-0.5Mg alloy. Figure 5 (b) is a photograph of the Al-7Si-0.25Mg alloy.

[0040] Under near-infrared imaging, the high-Mg-content Al-7Si-0.5Mg alloy appears black, while the low-Mg-content Al-7Si-0.25Mg alloy retains its original metallic color.

[0041] Under a regular camera, high-Mg-content Al-7Si-0.5Mg alloy appears black under an optical camera, while low-Mg-content Al-7Si-0.25Mg alloy appears as a metallic silver color. Different magnesium-containing recycled aluminum alloys can be clearly distinguished.

[0042] For recycled aluminum where zinc content needs to be controlled, dilute sulfuric acid solution can be used as a bleaching solution to remove the zinc-containing coloring layer. After bleaching, the waste aluminum alloy is put into the smelting furnace for regenerative smelting. At the same time, the dilute zinc sulfate solution can be used again as a coloring solution after slag removal and purification, thus realizing the repeated recycling of zinc ions.

[0043] Example 4

[0044] Using CuSO4 solution as the coloring solution, Al-3Cu-0.3Mg alloys and Al-3Cu-1.5Mg alloys with different magnesium contents were colored. The surface color of the Al-3Cu-1.5Mg alloy with higher magnesium content was significantly darker.

[0045] Example 5

[0046] Using CuCl2 solution as the coloring solution, 7075 aluminum alloy (Mg content 2.5%, commonly used in the automotive and aerospace industries) and 6063 aluminum alloy (Mg content 0.7%, commonly used in the door, window and curtain wall industries) with different magnesium contents were colored. The surface color of 7075 aluminum alloy with higher magnesium content was significantly darker.

[0047] The embodiments of the present invention have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention is not limited to the specific embodiments described above; these embodiments are merely illustrative and not limiting. Those skilled in the art, under the guidance of the present invention, can make many modifications without departing from the spirit and scope of the claims, and all such modifications fall within the scope of protection of the present invention.

Claims

1. A method for separating scrap aluminum alloys with different magnesium contents, characterized in that, Includes the following steps: Waste solid aluminum alloys with different magnesium contents are immersed in a coloring solution for surface coloring. The waste solid aluminum alloys with different magnesium contents are taken out of the coloring solution and then separated according to the color difference. The coloring solution includes any one of copper sulfate solution, copper chloride solution, zinc sulfate solution, and zinc chloride solution.

2. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, The concentration of the copper sulfate solution, copper chloride solution, zinc sulfate solution, or zinc chloride solution is 0.001 mol / L to 0.1 mol / L.

3. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, The coloring solution was a 0.05 mol / L copper sulfate solution.

4. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, The coloring solution was a 0.05 mol / L copper chloride solution.

5. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, The coloring solution was a zinc sulfate solution with a concentration of 0.001 mol / L.

6. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, The soaking time is 5 min-600 min, and the soaking temperature is 0℃-40℃.

7. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, Different magnesium content scrap aluminum alloys are separated by manual labor or cameras based on color differences.

8. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, Image recognition technology is used to automatically separate waste solid aluminum alloys with different magnesium contents based on color differences.

9. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, A bleaching solution is used to bleach the coloring layer of waste solid aluminum alloy. When the coloring solution contains zinc sulfate solution, the bleaching solution is a dilute sulfuric acid solution.

10. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that, A bleaching solution is used to bleach the coloring layer of waste solid aluminum alloy. When the coloring solution contains zinc chloride solution, the bleaching solution is a dilute hydrochloric acid solution.

Images