How to reduce the pollution in the processing of recycled aluminum

The rapid development of secondary aluminum industry in recent years reflects the problems existing in the production process. In order to scientifically expand the development of recycled aluminum, scientific and perfect processing technology should be formulated according to the characteristics of recycled aluminum raw materials, reasonable fuels and additives should be selected, and environmental-friendly aluminum ash separator should be selected to improve the recovery rate of metallic aluminum as much as possible and reduce secondary pollution. Strengthening the pretreatment of waste aluminum In the process of processing and manufacturing aluminum and its alloys, enterprises often treat the metal surface, spray various coatings or coat various organic (inorganic) materials, which may add substances such as acid, alkali, salt and oil. Therefore, aluminum and its products enter the scrap field after use or consumption, and they themselves carry pollutants. In addition, waste aluminum comes from all corners of society and has a wide variety. In the process of recycling and dismantling, it is polluted to varying degrees and will be mixed with various non-aluminum substances. These inclusions will also undergo physical and chemical reactions in the smelting process, which will have a certain impact on the environment. Therefore, attention should be paid to the pretreatment of waste aluminum to eliminate mixed pollutants before smelting. Pretreatment technology mainly includes: sorting, that is, sorting out non-aluminum substances such as plastics and rubber; Water washing, that is, washing away oil stains and other substances in waste aluminum; Depainting: In order to reduce the pollution caused by incomplete combustion of coating on the surface of waste aluminum, attention should be paid to the depainting treatment of coated waste aluminum before entering the furnace. At the same time of pretreatment, various non-aluminum substances are also separated to obtain pure waste aluminum, which is also a necessary guarantee for melting high-quality aluminum alloy. Because a large number of inclusions have been removed before smelting, the dosage of additives has been reduced, the smelting cycle has been shortened, and the production cost has been reduced accordingly, which shows the advantages of environmental management. Choosing fuel scientifically and economically can not only reduce energy consumption, but also obviously change the environment. At present, liquid fuel has better environmental benefits and higher combustion efficiency than solid fuel. Gas fuel has better environmental benefits and the best combustion efficiency than liquid fuel. Therefore, when choosing fuel, gas fuel should be used as much as possible. However, due to the limitation of conditions, gas fuel cannot be used anywhere. At present, many secondary aluminum enterprises have established gas generators to convert solid fuel into gas fuel, which not only greatly reduces the pollution caused by coal burning, but also reduces the production cost due to the improvement of combustion efficiency, which is undoubtedly a scientific choice. Do not use additives that have an impact on the environment. Additives used in aluminum industry are mainly solvents (covering agents) and refining agents. Judging from the various additives currently used, it is generally believed that chlorine, hexachloroethane and zinc chloride are polluting the environment. Chlorine is rarely used to refine aluminum melt, but it is still used in some alloys with special requirements. Hexachloroethane and zinc chloride are also used, and some non-toxic refining agents produced by some manufacturers contain a large amount of hexachloroethane. It is suggested that enterprises choose additives that do not pollute the environment, such as inert gas or nitrogen. Improve the treatment technology of aluminum ash. The aluminum content in aluminum ash is high, so it must be recycled. In order to avoid pollution caused by aluminum recovery from aluminum ash, it is suggested that large-scale enterprises should adopt rotary kiln to treat aluminum ash or press to recover aluminum from aluminum ash, and the treated ash should be deeply recovered by environmental protection aluminum ash separator to improve the recovery rate, minimize the pollution caused by aluminum ash treatment and improve the recovery rate.