Method for separating waste aluminum alloys with different magnesium contents

Abstract

The invention discloses a method for separating waste aluminum alloys with different magnesium contents, which is characterized by comprising the following steps: soaking the waste aluminum alloys with different magnesium contents in a coloring solution for surface coloring, taking out the waste aluminum alloys with different magnesium contents from the coloring solution, and then separating the waste aluminum alloys with different magnesium contents according to chromatic aberration, the coloring solution comprises any one of a copper sulfate solution, a copper chloride solution, a zinc sulfate solution and a zinc chloride solution. The invention provides a scheme for separating the waste aluminum alloys with different magnesium contents, and a large amount of magnesium removal agent or pure aluminum is prevented from being added, so that the advantages of preparing the secondary aluminum from the waste aluminum alloys are fully exerted; the scheme is simple in process, raw materials are easy to obtain, cost is low, and automatic sorting is convenient to achieve.

Description

Technical Field

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

[0002] Recycled aluminum is an aluminum alloy material produced from scrap aluminum alloy products and aluminum materials through smelting, refining, and other processes. Compared to primary aluminum (extracted from bauxite), recycled aluminum offers significant advantages: energy conservation and environmental protection. Recycled aluminum consumes only about 5% of the energy of primary aluminum, reducing energy consumption by 95% and carbon emissions by over 90%. Recycled aluminum's mechanical properties and corrosion resistance are comparable to primary aluminum, meeting the needs of industries such as automotive, construction, and packaging, achieving a closed-loop resource utilization. The production cost of recycled aluminum is 30%-50% lower than primary aluminum, and the production process is shorter, helping companies 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 key step in recycling and directly affects the purity and performance of recycled aluminum. Based on the sorting principles and technical means, the sorting methods for scrap aluminum alloys can be mainly divided into the following categories: 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 chips) from aluminum and is suitable for preliminary iron removal. Eddy current separation uses an alternating magnetic field to generate eddy currents in non-ferrous metals (such as aluminum) based on differences in electrical conductivity, ejecting them and separating them. This method is suitable for sorting mixed metal scrap. Gravity separation uses density differences to separate aluminum from lightweight impurities such as plastics and rubber through wind, water, or vibrating screening.

[0004] Chemical separation methods include flotation and smelting refining. Flotation uses chemicals to adjust the surface properties of aluminum and impurities, separating them within bubbles and is suitable for treating fine-grained aluminum slag. Smelting refining uses fluxes (such as salt solvents) to remove aluminum oxide and other non-metallic inclusions in a high-temperature molten state, thereby improving the purity of the molten aluminum.

[0005] Intelligent sorting technologies include X-ray fluorescence (XRF) sorting, laser-induced breakdown spectroscopy (LIBS), and artificial intelligence (AI) sorting. X-ray fluorescence (XRF) sorting uses X-rays to identify the alloying components in aluminum, enabling high-precision sorting. Laser-induced breakdown spectroscopy (LIBS) uses lasers to analyze the elemental composition of aluminum and is suitable for the precise classification of high-end recycled aluminum. Artificial intelligence (AI) sorting combines machine vision and deep learning to automatically identify and sort aluminum scrap of different types and specifications, improving sorting efficiency and accuracy.

[0006] Manual sorting is suitable for small-scale recycling or pre-processing stages. It separates aluminum products through manual screening, knocking and identification. It has low cost and limited efficiency.

[0007] Different sorting methods can be used alone or in combination, and the specific choice depends on the source of the scrap aluminum, the type of impurities and the purpose of the recycled aluminum.

[0008] However, the current separation technology for recycled aluminum presents a significant challenge in the separation of magnesium-containing aluminum alloys. Because the specific gravity of magnesium is comparable to that of aluminum and their atomic numbers are adjacent, aluminum alloys with varying magnesium contents have similar specific gravities, making separation difficult during the separation process. Furthermore, the physical and magnetic properties of aluminum and magnesium are similar, making accurate separation impossible even under X-ray analysis. This necessitates the use of magnesium removal when producing recycled aluminum from scrap aluminum alloys containing high magnesium contents. This removal requires the addition of large amounts of magnesium removal agents, and due to the high temperature of the aluminum melt during the removal process, aluminum burnout is severe, resulting in very high costs. If pure aluminum is used for dilution due to the high magnesium content, the amount of new aluminum required would be very high, hindering the full potential of recycled aluminum. Therefore, simply and efficiently separating scrap aluminum alloys with varying magnesium contents is crucial for fully realizing the advantages of recycled aluminum. Summary of the Invention

[0009] In order 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 the simple, efficient and low-cost separation of scrap aluminum alloys with different magnesium contents, 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.

[0010] A method for separating scrap aluminum alloys with different magnesium contents, characterized by comprising the following steps: immersing the scrap aluminum alloys with different magnesium contents in a coloring solution for surface coloring, taking out 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 color difference; the coloring solution comprises any one of a copper sulfate solution, a copper chloride solution, a zinc sulfate solution, and a zinc chloride solution.

[0011] Using this technical solution, scrap aluminum alloys with varying magnesium contents are tinted by immersing them in a coloring solution. The magnesium element in the scrap aluminum alloy has the strongest reducing properties, displacing copper and zinc ions from the solution. Due to the varying magnesium content, the scrap aluminum alloy blocks with varying magnesium contents form different morphologies after displacement, resulting in different color layers under ordinary and infrared light. Scrap aluminum alloys with high magnesium contents have a darker color, while those with low magnesium contents have a lighter color. This allows for separation of scrap aluminum alloys with varying magnesium contents based on color differences.

[0012] Furthermore, the concentration of the copper sulfate solution, copper chloride solution, zinc sulfate solution or zinc chloride solution is 0.001 mol / l-0.1 mol / l. Preferably, the coloring solution is a copper sulfate solution with a concentration of 0.05 mol / l, or the coloring solution is a copper chloride solution with a concentration of 0.05 mol / l, or the coloring solution is a zinc sulfate solution with a concentration of 0.001 mol / l.

[0013] Furthermore, the soaking time is 5 min-600 min, and the soaking temperature is 0° C.-40° C.

[0014] Furthermore, scrap aluminum alloys with different magnesium contents can be separated manually or by camera based on color difference. Alternatively, image recognition technology combined with machine learning can be used to automatically separate scrap aluminum alloys with different magnesium contents based on color difference.

[0015] Furthermore, the colored layer of the scrap aluminum alloy is decolorized using a decolorizing solution, such as a dilute hydrochloric acid solution or a dilute sulfuric acid solution. For recycled aluminum in which the zinc content needs to be controlled, the zinc-containing coloring layer (colored layer) can be removed using a dilute hydrochloric acid solution or a dilute sulfuric acid solution. The colored scrap aluminum alloy can then be briefly immersed in the decolorizing solution or rinsed with the decolorizing solution. The decolorized scrap aluminum alloy is then fed into a smelting furnace for regenerative smelting. Simultaneously, the dilute zinc sulfate solution or the dilute zinc chloride solution is deslagging and purified and can be reused as the coloring solution, thus achieving the repeated recycling of zinc ions.

[0016] The present invention has the following beneficial effects.

[0017] 1. The present invention innovatively proposes a solution for separating scrap aluminum alloys with different magnesium contents, avoiding the addition of large amounts of magnesium removal agents or pure aluminum, thereby giving full play to the advantages of preparing recycled aluminum from scrap aluminum alloys.

[0018] 2. The process of the present invention is simple, the raw materials are easily available, the cost is low, and it is easy to realize automatic sorting.

[0019] 3. In particular, when zinc chloride solution or zinc sulfate solution is used as the coloring solution and dilute hydrochloric acid solution or dilute sulfuric acid solution is used as the decoloring solution, the zinc ions can be recycled and reused, thereby further reducing the process cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The following are photos of scrap aluminum alloys with different magnesium contents after separation in Example 1, taken under a near-infrared camera, where: Figure 1 (a) and Figure 1 (b) is a photograph of Al-7Si-0.5Mg alloy. Figure 1 (c) and Figure 1 (d) is a photograph of Al-7Si-0.25Mg alloy.

[0021] Figure 2 The following are photos of scrap aluminum alloys with different magnesium contents after separation in Example 1, taken with an ordinary camera, where: Figure 2 (a) is a photograph of Al-7Si-0.5Mg alloy. Figure 2 (b) is a photograph of Al-7Si-0.25Mg alloy.

[0022] Figure 3 The following are photos of scrap aluminum alloys with different magnesium contents after separation in Example 2, taken with an ordinary camera. Figure 3 (a) is a photo of Al-7Si-0.5Mg alloy. Figure 3 (b) is a photograph of Al-7Si-0.25Mg alloy.

[0023] Figure 4 The following are photos of scrap aluminum alloys with different magnesium contents after separation in Example 3, taken with an ordinary camera. Figure 4 (a) is a photo of Al-7Si-0.5Mg alloy. Figure 4 (b) is a photograph of Al-7Si-0.25Mg alloy.

[0024] Figure 5 The following are photos of scrap aluminum alloys with different magnesium contents after separation in Example 3, taken under a near-infrared camera. Figure 5 (a) is a photograph of Al-7Si-0.5Mg alloy. Figure 5 (b) is a photograph of Al-7Si-0.25Mg alloy. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] Taking waste aluminum-silicon-magnesium alloy as an example, Al-7Si-0.25Mg alloy and Al-7Si-0.5Mg alloy were separated.

[0028] The specific operations are as follows: The coloring was performed using a CuSO4 solution at a concentration of 0.05 mol / l, a 45-minute immersion time, and a temperature of 25°C. 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 exhibited a removable flocculent brown substance. After cleaning the surface, images were taken using both a standard camera and a near-infrared camera (Madview MV-GEC130I short-wave infrared industrial camera). The results are shown below. Figure 1 and Figure 2As shown. Among them, Figure 1 (a) and Figure 1 (b) is a photograph of Al-7Si-0.5Mg alloy. Figure 1 (c) and Figure 1 (d) is a photograph of Al-7Si-0.25Mg alloy; Figure 2 (a) is a photograph of Al-7Si-0.5Mg alloy. Figure 2 (b) is a photograph of Al-7Si-0.25Mg alloy.

[0029] By comparison, the high Mg content Al-7Si-0.5Mg alloy appears bright under the near-infrared camera ( Figure 1 ), which appears brown under ordinary cameras ( Figure 2 ), the low Mg content Al-7Si-0.25Mg alloy appears dark under the near-infrared camera ( Figure 1 ), under ordinary cameras, it appears as a metallic silver background with a small amount of brown copper discontinuously distributed ( Figure 2 ), alloys with different magnesium contents can be clearly distinguished, and the composition can be controlled within the error range of the alloy grade.

[0030] For recycled aluminum that needs to have its copper content controlled, a copper stripping solution can be used to remove the copper-containing color layer. This reduces copper contamination of the aluminum melt. The copper stripping solution contains 0.5-3% copper stripping accelerator, 2-5% sodium dodecylbenzene sulfonate, 0.1-0.3% boric acid, 1-3% malic acid, 3-5% sodium bromate, 3-5% nitric acid, and the balance water.

[0031] Example 2

[0032] ZnCl2 was used as the coloring solution to color the Al-7Si-0.25Mg alloy and the Al-7Si-0.5Mg alloy. The specific operation was as follows: The concentration of ZnCl2 solution is 0.01mol / l, the immersion time is 5min, and the temperature is 20℃. After immersion, the high Mg content Al-7Si-0.5Mg alloy appears dark black, and the low Mg content Al-7Si-0.25Mg alloy appears gray. After cleaning the surface, take pictures with an ordinary camera. The results are as follows Figure 3 shown. Figure 3 (a) is a photograph of Al-7Si-0.5Mg alloy. Figure 3 (b) is a photograph of Al-7Si-0.25Mg alloy.

[0033] For recycled aluminum that needs to control the zinc content, dilute hydrochloric acid solution can be used as a fading solution to remove the zinc-containing color layer. The scrap aluminum alloy after fading treatment is put into the smelting furnace for regeneration smelting. At the same time, the dilute zinc chloride solution can be removed and purified and used as a coloring solution again, realizing the repeated recycling of zinc ions.

[0034] Example 3

[0035] ZnSO4 was used as the coloring solution to color the Al-7Si-0.25Mg alloy and the Al-7Si-0.5Mg alloy. The specific operation is as follows: The concentration of ZnSO4 solution was 0.001mol / l, the immersion time was 10 hours, and the temperature was 20℃. After immersion and cleaning, the surface was photographed with a normal camera and a near-infrared camera (MadeVision 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 Al-7Si-0.5Mg alloy. Figure 4 (b) is a photograph of Al-7Si-0.25Mg alloy; Figure 5 (a) is a photograph of Al-7Si-0.5Mg alloy. Figure 5 (b) is a photograph of Al-7Si-0.25Mg alloy.

[0036] Under the near-infrared camera, the high-Mg content Al-7Si-0.5Mg alloy appears black, while the low-Mg content Al-7Si-0.25Mg alloy appears the original color of the metal.

[0037] Under ordinary cameras, the high-Mg content Al-7Si-0.5Mg alloy appears black under optical cameras, while the low-Mg content Al-7Si-0.25Mg alloy appears as the original silver metal. This allows for clear differentiation of recycled aluminum alloys containing different magnesium contents.

[0038] For recycled aluminum that needs to control the zinc content, dilute sulfuric acid solution can be used as a fading solution to remove the zinc-containing color layer. The scrap aluminum alloy after fading treatment is put into the smelting furnace for regeneration smelting. At the same time, the dilute zinc sulfate solution can be deslagging and purified and used as a coloring solution again, realizing the repeated recycling of zinc ions.

[0039] Example 4

[0040] CuSO4 solution was used as the coloring solution to color Al-3Cu-0.3Mg alloy and Al-3Cu-1.5Mg alloy with different magnesium contents. The surface color of the Al-3Cu-1.5Mg alloy with high magnesium content was obviously darker.

[0041] Example 5

[0042] CuCl2 solution was used as the coloring solution to color 7075 aluminum alloy (Mg content 2.5%, commonly used in the automotive and aviation fields) and 6063 aluminum alloy (Mg content 0.7%, commonly used in doors, windows, and curtain walls) with different magnesium contents. The surface color of the 7075 aluminum alloy with a high magnesium content was significantly darker.

[0043] The embodiments of the present invention are described above in conjunction with the accompanying drawings. The embodiments of the present invention and the features thereof may be combined with each other unless there is any conflict. The present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Under the guidance of the present invention, those skilled in the art may devise various forms without departing from the spirit of the present invention and the scope of protection of the claims. All of these forms 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: The following steps are involved: The scrap aluminum alloys with different magnesium contents are immersed in a coloring solution to color the surface, the scrap aluminum alloys with different magnesium contents are taken out from the coloring solution, and then the scrap aluminum alloys with different magnesium contents are separated according to 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-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 is a copper sulfate solution with a concentration of 0.05 mol / l.

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

5. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that: The coloring solution is 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°C-40°C.

7. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that: Use manual labor or cameras to separate scrap aluminum alloys with different magnesium contents based on color difference.

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 scrap aluminum alloys with different magnesium contents based on color difference.

9. The method for separating scrap aluminum alloys with different magnesium contents according to claim 1, characterized in that: A fading solution is used to fade the colored layer of the waste aluminum alloy. When the coloring solution contains a zinc sulfate solution, the fading 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 fading solution is used to fade the colored layer of the waste aluminum alloy. When the coloring solution contains a zinc chloride solution, the fading solution is a dilute hydrochloric acid solution.

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