Nowadays, all over the world, the main method of processing aluminum scrap is remelting in units of various types. Sources of impurities are the composition of the alloy for producing drink cans (mainly, Al–Mg alloy containing up to 3%–4% Mg) and mechanical impurities that enter into the scrap due to inefficient sorting, classification, and storage of the scrap. Magnesium, zinc, silicon, iron, etc., are the main impurities. Aluminum scrap has a complex chemical composition based on aluminum (> 90%). In recent years, the processing of aluminum scrap (mainly chips and used drink cans) has attracted increasing attention. Gopienko, in Handbook of Non-Ferrous Metal Powders (Second Edition), 2019 Processing of Recycled Aluminum to Granules Some scrap types, like Used Beverage Containers (UBCs), are easily identified, but most postconsumer scrap is at best identified between one of several broad categories. Typically, postconsumer scrap is a mixture of alloys and sometimes even a mixture of metals. Once the part is installed in a larger assemblage or is delivered to a customer, the traceability of the part decreases. Manufacturing scraps could include stamping skeletons, machine turnings, scrapped pieces due to imperfections, or any other form due to a multitude of reasons. This type of scrap has the highest value due to its known pedigree. When the scrap is generated at a subsequent manufacturing operation, it is highly likely that the scrap will return to a recycling operation and will normally be returned to the original alloy since the pedigree is known.
When the machining operations take place within the aluminum mill, the scrap is always returned to the cast house and remelted. In a manufacturing operation, this is normally a simple operation. Based on Figure 2.5.25, it makes the most sense to return a scrap material to the same alloy or at least the same family whenever possible. During manufacturing, aluminum material is lost from the process either during the melting step to form dross or in one of the many machining operations applied to the aluminum piece. Peterson, in Treatise on Process Metallurgy: Industrial Processes, 2014 2.5.3.1.1.2 Sources and Material FlowĪluminum scrap is generated in many steps of the manufacturing process and use by the end user.
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