Apply a magnet to each component to weed out steel and iron from your aluminum scrap. Magnetic separation is the primary method used in the identification of aluminum among scrap metals. Aluminum in not magnetic, whereas visually similar metals to aluminum, such as iron and steel, are attracted to magnets. Used beverage cans, for example, are easily identified and sorted from their steel counterparts using magnetic separation. More complicated objects, which combine various materials in their construct and rely on alloys, must first be broken down before identifying the aluminum.
Sort the metals by color. The broader method of manual identification of aluminum scrap involves color sorting. A visual inspection of the materials can help to separate obvious metals such as copper and zinc. Copper would take on a reddish-brown appearance, and brass, a copper-zinc alloy, would appear as a light golden color.
Break down large objects. If you’re tearing apart an old car, for example, break down the larger, multi-component sections before identifying what materials you’re dealing with. For sections that are welded together such as the radiator ends, you may have to use a hand saw to cut them. For smaller, more numerous components, such as those in a computer, light air suction can be used to remove the lighter foam, wire and plastic pieces from the pile before magnetically separating your aluminum.
Check the appropriate density of the nonmagnetic sections. For smaller materials, it is possible to use water to separate the tiny pieces by their specific gravities. Aluminum is one-third the weight of either steel or copper and therefore begins to float at a specific gravity of 2.5 and greater. Yielding a specific gravity of 2.5 and greater will also cause other particles, such as rubber, plastic and insulated wire, to float. These non-magnetic pieces are able to be separated by visual inspection, but for magnesium, which will also float at a specific gravity of 2.5, you will have to use magnetic separation.