With the enhancement of environmental awareness and the increase in the demand for resource recycling, the regeneration and utilization of waste aluminum cans have become increasingly important. This article elaborates in detail the working principles, characteristics and application advantages of new technologies and equipment involved in the recycling process of waste aluminum cans, such as paint removal kilns, electromagnetic pumps, multi-chamber furnaces and new degassing and filtration equipment. The application of these new technologies and equipment has significantly enhanced the efficiency and quality of the recycling and utilization of waste aluminum cans, promoting the sustainable development of the aluminum circular economy.
I. Introduction
Aluminum cans are widely used in beverage packaging and other fields due to their advantages such as light weight, easy processing and recyclability. With the continuous growth of consumption, the number of waste aluminum cans is also increasing day by day. Efficient recycling and reuse of it can not only alleviate the shortage of aluminum resources, but also reduce energy consumption and environmental pollution, which is a key measure to achieve sustainable development in the aluminum industry. In recent years, the application of new equipment in the recycling and utilization of waste aluminum cans has brought new development opportunities to this field.
Ii. The Importance of Recycling and Reusing Waste Aluminum Cans
The production process of aluminium consumes a huge amount of energy. From bauxite mining to the preparation of electrolytic aluminium, a large amount of energy is needed. In contrast, the energy consumption for recycling waste aluminum cans is only about 5% of that for primary aluminum production. According to statistics, for every one ton of waste aluminum cans recycled and reused, approximately 3.4 tons of standard coal can be saved and about 20 tons of solid waste discharge can be reduced. This is of great significance for easing the global energy shortage and reducing carbon emissions.
If a large number of waste aluminum cans are not properly disposed of, they will occupy land resources and may also cause environmental pollution. Through recycling and reuse, it can be transformed into high-value aluminum products, achieving the circular and graded utilization of resources, reducing reliance on primary resources, and conforming to the concept of circular economic development.
Iii. Paint Stripping Kiln Technology and Its Application
3.1 Working Principle
The surface of traditional waste aluminum cans is coated with various paints and coatings. Direct smelting will increase the burning loss of aluminum and produce a large amount of harmful gases. The temperature inside the paint removal kiln is controlled at 380 to 500℃. Once the heating starts and reaches a certain temperature, the heat is mainly released during the carbonization process of the paint layer on the surface of the waste aluminum. In the high-temperature atmosphere inside the kiln, the paint coating on the surface of the waste aluminum is carbonized, and the paint layer falls off due to the self-vibration during the rotation of the kiln body. At the same time, the moisture in the waste aluminum will also be dried, eliminating the possibility of water reacting with the aluminum melt during the remelting process, ensuring the safety of production. For thin-walled waste materials with coatings or paints, the recovery rate of aluminum directly melted in the furnace is low. However, if the paint is removed in advance before melting, the recovery rate will be greatly increased. Through heat exchange and rapid cooling, the emission of dioxins can be minimized to the greatest extent, reducing environmental pollution.
3.2 Technical Advantages
The paint removal kiln can efficiently remove the paint layer on the surface of waste aluminum cans, with a removal rate of over 95%. Compared with traditional manual or chemical paint removal methods, the paint removal efficiency is significantly improved, and it is not restricted by the shape and size of waste aluminum cans, enabling large-scale continuous processing. During the paint removal process, the heat generated from the decomposition of organic matter can be partially recovered and utilized to preheat the waste aluminum cans entering the paint removal kiln or other processes, thereby reducing the overall energy consumption. In addition, the waste gas produced by the paint stripping kiln is purified and discharged up to standard, reducing pollution to the environment.
3.3 Application Cases
In a large-scale recycled aluminum enterprise, a set of Kunshan Zhongneng paint removal kiln (Kunshan Zhongneng Industrial Equipment Co., LTD. – a leader in the field of efficient paint removal technology for waste aluminum) has been introduced. The paint stripping kiln has a daily processing capacity of 50 tons for waste aluminum cans. After the paint removal treatment, when the waste aluminum cans enter the subsequent smelting process, the burning loss rate of aluminum is significantly reduced, dropping from 8% – 10% before paint removal to 3% – 5%. Meanwhile, due to the reduction of harmful gases produced by the combustion of the paint layer, the air quality in the smelting workshop has been significantly improved, and the surrounding environment has also been effectively protected.
Iv. Electromagnetic Circulation Pump Technology and Applications
4.1 Working Principle
The electromagnetic pump operates based on the principle of electromagnetic induction. In the structure of an electromagnetic pump, the coil through which an alternating current is passed will generate an alternating magnetic field. When liquid metal in a magnetic field (such as the molten aluminum from recycled aluminum cans) passes through, an induced current will be generated in the molten aluminum. According to Lenz’s law, the induced current interacts with the magnetic field to generate electromagnetic force. Under the action of this electromagnetic force, the molten aluminum will overcome its own gravity and flow resistance, and flow in the predetermined direction, achieving the functions of transporting and stirring the molten aluminum.
4.2 Technical Advantages
Compared with traditional mechanical pumps, electromagnetic pumps have no mechanical moving parts, avoiding mechanical wear and sealing problems, which greatly extends the service life of the equipment and reduces maintenance costs. The electromagnetic pump can precisely control the flow rate and velocity of the molten aluminum. By adjusting the magnitude and frequency of the input current, the precise control of the molten aluminum conveying volume can be achieved, which is crucial for ensuring the stability of the subsequent casting process and product quality. Moreover, during the process of transporting molten aluminum, the electromagnetic pump can ensure uniform mixing of the molten aluminum, reduce component segregation, and improve the quality of the molten aluminum.
4.3 Application Cases
A certain aluminum processing enterprise has adopted electromagnetic pumps for the transportation of molten aluminum in its waste aluminum can recycling production line. During the production process, the production efficiency has increased by more than 20%. Meanwhile, due to the stable operation of the electromagnetic pump, the production halt time caused by equipment failure has been reduced, and the economic benefits of the enterprise have been significantly improved.
V. Multi-Chamber Furnace Technology and Its Applications
5.1 Structure and Working Principle
Multi-chamber furnaces are usually composed of multiple furnace chambers with different functions, generally including preheating chambers, melting chambers, refining chambers, etc. Waste aluminum cans first enter the preheating chamber, where they are preheated by the residual heat generated from the subsequent melting chamber and refining chamber, thereby enhancing energy utilization efficiency. In the melting chamber, waste aluminum cans are melted by means of fuel combustion or electric heating, etc. The refining chamber is used for further refining the molten aluminum to remove impurities and gases from it. Each chamber is connected through specific channels, and the molten aluminum flows orderly between different chambers, completing the entire smelting process.
5.2 Technical Advantages
The waste heat utilization design of multi-chamber furnaces significantly reduces energy consumption. Compared with traditional single-chamber melting furnaces, energy consumption can be reduced by 20% to 30%. By carrying out targeted treatment in different rooms, impurities and gases in waste aluminum cans can be removed more effectively, and the purity of the aluminum liquid can be improved. For example, by adopting methods such as air blowing refining in the refining chamber, the hydrogen content in the molten aluminum can be reduced to below 0.15ml/100gAl, and the content of inclusions is significantly decreased. The continuous production mode of multi-chamber furnaces has enhanced production efficiency and enables the large-scale recycling and utilization of waste aluminum cans.
5.3 Application Cases
A certain recycled aluminum factory has installed a multi-chamber furnace with a three-chamber structure for smelting waste aluminum cans. After the multi-chamber furnace is put into use, it can process 50,000 tons of waste aluminum cans annually. The quality of the recycled aluminum ingots produced meets the national standards. Moreover, due to the high purity of the molten aluminum, the competitiveness of the products in the market has been significantly enhanced. Meanwhile, the multi-chamber furnace has a remarkable energy-saving effect, saving enterprises about one million yuan in energy costs each year.
Vi. New Degassing and Filtration Equipment and Its Applications
6.1 Working Principle
New degassing and filtration equipment usually combines multiple technologies, such as bubble floating degassing and filtration with filter media. During the degassing process, inert gases (such as argon) are introduced into the molten aluminum to form tiny bubbles. Since the partial pressure of hydrogen in the bubble is zero, the hydrogen in the molten aluminum will diffuse into the bubble and be discharged as the bubble rises, achieving the purpose of degassing. The filtration section adopts new types of filtration materials, such as high-precision foam ceramic filter plates, which have a uniform pore structure and can effectively prevent inclusions in the aluminum liquid from passing through, thus purifying the aluminum liquid.
6.2 Technical Advantages
The new degassing and filtration equipment has a high degassing efficiency. It can reduce the hydrogen content in the molten aluminum to below 0.1ml/100gAl, and the removal rate of inclusions can reach over 90%. Compared with traditional degassing and filtration equipment, it has higher filtration accuracy, can effectively remove tiny inclusions, and improve the quality of recycled aluminum. The equipment is easy to operate and can run online without affecting the continuity of production. Moreover, the maintenance cost is relatively low, the filter material has a long service life and is easy to replace.
6.3 Application Cases
An enterprise specializing in the production of high-end aluminum alloy products has adopted advanced new degassing and filtration equipment in its waste aluminum can recycling production line. The molten aluminum processed by this equipment is used to produce flat ingots for tank materials. The internal quality of the product has been significantly enhanced, and its mechanical properties have also been notably improved, meeting the strict requirements of the can material market for the quality of aluminum alloy products.
Vii. Conclusion
New technologies and equipment such as paint removal kilns, electromagnetic pumps, multi-chamber furnaces, and new degassing and filtration devices have played a significant role in the recycling and utilization of waste aluminum cans. The application of these technologies and equipment has enhanced the efficiency and quality of recycling waste aluminum cans, reduced energy consumption and environmental pollution, and promoted the development of the aluminum circular economy. In the future, with the continuous advancement of technology, the field of recycling and reusing waste aluminum cans will witness the emergence of more advanced technologies and equipment, further enhancing the level of resource recycling and utilization, and making greater contributions to the sustainable development of the aluminum industry.
Post time: May-09-2025