[China Aluminum Industry Net] Aluminum and aluminum alloy scrap are collectively referred to as scrap aluminum. Among the metals used in national economic construction, the recyclability of aluminum is relatively high. This has four meanings. The first is that aluminum has strong resistance. Corrosion performance, almost no corrosion in the atmosphere, only forms a thin layer of aluminum oxide film on the surface, in fact, this layer of aluminum oxide film is thinner than the flap, its thickness is only about 5nm (nanometer), Its quality is negligible. At the same time, it is very dense, oxygen is impenetrable, and it can not only block oxygen from entering. That is to say, once it is formed, it will protect the aluminum from oxidation. His formation speed is extremely fast. The "fresh" aluminum is exposed. In the atmosphere, it immediately reacts with oxidation to form a film. If the oxide film on the aluminum is destroyed, a new film will be formed instantaneously, which means that the surface oxide film of aluminum and aluminum alloy has a strong "self-healing" capability, and the second is to say that the aluminum oxide film is in the process of remelting With low energy consumption and low burning, the energy consumption of scrap aluminum in the remelting process is only equivalent to about 5% of the total energy consumption of primary aluminum extraction (the sum of the energy consumption of bauxite mining, alumina extraction, and primary aluminum production). About 870kwt/a; The waste aluminum scrap discharged is less than 1/25th of the original aluminum extraction. The dark gray benefit is very obvious. It takes 2 tons of bauxite to extract 1 ton of alumina and produces solid waste - red mud about 1 Tons of red mud, although not a toxic substance, is harmful and is an alkaline substance. The inclusion of alkalis in the farmland into the water system will cause harm and pollute the bad environment. At the same time, it needs a lot of space to store it. Once the dam breaks, the consequences will be disastrous. At the same time, it will take up a large amount of valuable farmland resources. In the alumina extraction process, a large amount of water will be consumed, and the discharged water will be polluted to varying degrees. The electrolytic aluminum market needs to consume 1 ton of primary aluminum. About 450kg of carbon, carbon becomes co2 and co to warm Gas-type discharge into the atmosphere, the electrolytic production of aluminum will emit fluoride gas, although most of these fluorides are recycled, but there is a non-negligible amount of discharged into the atmosphere, causing harm, because fluoride is toxic, and aluminum scrap When remelted with natural gas or diesel, only co2 is emitted. If the combustion is not complete, a small amount of co will be released, but the amount of them is much less than that of electrolysis. Fourth, the quality of recycled aluminum produced by modern technology and equipment can be improved. Fully equivalent to the quality of the original aluminum, for example, 6063 alloy ingots smelted with aluminum waste construction can be used to extrude new 6063 alloy building profiles, the use of waste electrical wire smelting conductive aluminum alloy with the weight of A199.7E There is no difference in the production of melting ingots.
The length of the shares after the aluminum has been put into use varies. The long service life of buildings and structures can be as long as 50 or 60 years or more. Short, such as beer and beverage cans can be recycled in the market for 40 to 50 days. . If China's average payback period is calculated based on 18 years and the recoverability rate is calculated at 72%, about 100g remains after 1 ton of aluminum is in use for 500 years. It can be seen that aluminum is a metal with a long life cycle and is highly recoverable. The metal, which is a metal with a large amount of regenerative benefits, is indeed a longer life metal than Nanshan.
Why is the recovery rate of aluminum calculated by 72%? This is a figure drawn by the author's long-term work. Although it can not be very accurate, it is still not out of line as a calculation and as a macro-monitoring. Because some aluminum has been put into use and disappeared, it will never be recovered. Those aluminum can not be recycled? Aluminum powder for firecrackers, fuels, and paints; aluminum for the manufacture of pharmaceuticals, chemical products, and water purifiers; aluminum for steelmaking as a deoxidizer; aluminum for alloying elements in gold metallurgy for the preparation of magnesium alloys, aluminum bronze, titanium When alloys, high-temperature steels, and zinc alloys are used, they must consume a considerable amount of aluminum, double-zero aluminum foil for packaging medicines and foods, and some beverages (beer) cosmetics, etc., and manufacture aluminum for artillery shells, combustion, etc., to manufacture part of aluminum for spacecrafts. , Three-piece can lids and easy-to-remove lids, and small pieces of aluminum that cannot be disassembled with rigid cast iron and other materials; aluminum burned during the smelting process, and aluminum lost during the processing of aluminum materials, such as aluminium powder normally ground. , Extruded aluminum loss, surface treatment of washed aluminum and converted and oxidized aluminum, steel plate with aluminum or aluminum - zinc alloy consumption of aluminum and so on. After careful processing and evaluation, the authors obtained 72% of the aluminum that can be recycled in one use cycle, which is available for reference and use.
The 72% scrap aluminum refers to the actual recovery rate that is recoverable, and the actual recovery rate is much smaller than the number of times. The author believes that the actual recovery rate in the world is 60%, and the actual recovery rate depends on time, region, new year and location. The recoveries of developed countries may be higher for a certain product and lower for another product. Generally speaking, the recovery rate of developing countries is high. For example, the recovery rate of aluminum cans is the highest in the United States. The knowledge is not about 60%, Brazil is more than 80%, Sweden is 92%, China is about 99%. There is almost no submergence. According to the author's investigation, there are 4 or 5 recycling fees in China. The family recycling child recycles and the garbage collector recovers. In theory, the recyclability of cans should be more than 98%, but the actual recovery rate will not exceed 75%, because the United States consumes more than 50% of the world's cans, and its actual recovery rate is very low.
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