[China Aluminum Industry Network] Do you know what aluminum scrap is made of?
1. Guangzhou Scrap Recycling: Aluminum scrap often contains non-metallic impurities like paint, oil, plastic, and rubber. Before it can be smelted, these contaminants must be removed as much as possible. For wire-type aluminum scrap, methods such as mechanical abrasion, shear stripping, heat treatment, or chemical cleaning are commonly used to remove the insulation layer. In China, many companies still rely on high-temperature ablation to strip insulation, but this process releases a lot of harmful gases, causing serious air pollution.
2. A more environmentally friendly approach involves low-temperature baking followed by mechanical peeling. The insulator is first softened with heat, making it easier to remove through mechanical rubbing. This not only purifies the material but also allows for the recovery of the insulating material. Surface contaminants like paint and oil on aluminum waste containers can be cleaned using solvents such as acetone. If that doesn't work, paint-stripping ovens are an alternative. The temperature in these ovens should not exceed 566°C, and with sufficient exposure time, most coatings and oils can be effectively removed.
3. Iron impurities are a major concern in the recycling of aluminum scrap. Excess iron can lead to the formation of brittle metal crystals, reducing the strength and corrosion resistance of the final product. Ideally, iron content should be kept below 1.2%. Aluminum scrap with iron content above 1.5% is typically not used for producing commercial aluminum alloys but may be used as a deoxidizer in the steel industry. Unfortunately, there's currently no efficient method in the aluminum industry to effectively remove excess iron, especially when it comes in the form of stainless steel.
4. Guangzhou Waste Recycling: Separating aluminum foil from paper fibers is challenging. Traditional waste paper pulping equipment struggles to do so effectively. However, an innovative method involves soaking the aluminum foil in an aqueous solution, applying heat and pressure, then rapidly releasing the pressure to cause decomposition and mechanical mixing. This technique allows for the recovery of both the fiber pulp and the aluminum foil.
5. The future of aluminum recycling lies in the liquefaction and separation of waste aluminum. This method combines the pretreatment of aluminum waste with re-melting, streamlining the process, reducing environmental impact, and significantly increasing the recovery rate of valuable metals. As the industry moves toward greener practices, such technologies will play a crucial role in sustainable aluminum production.
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