(1) High-grade slices
The main components of high-grade scrap aluminum slices are cast aluminum alloy, alloy aluminum, pure aluminum, etc. Among them, there are many grades of the first two, and it is difficult to classify by grade. The soil, etc., can be directly smelted into the furnace. In small secondary aluminum enterprises, such scrap aluminum has to be manually divided into cast aluminum alloy, alloy aluminum and pure aluminum, and then used separately.
(2) Low-grade slices
For low-grade slicing and incinerated shredded aluminum scrap (the latter is generally not used in large recycled aluminum plants), it is necessary to carry out more complex sorting, because of its extremely complex composition, in addition to scrap aluminum, it also contains scrap steel, scrap copper, scrap metals such as lead, and other wastes. The sorting of such wastes is mainly manual. First, the soil and garbage are screened out, and then sorted by hand. Most of the manual sorting is carried out on the operating table, mainly relying on the visual inspection and experience of the workers. First, the non-metallic scrap is sorted, and then the scrap metal is sorted. Among them, the selection of scrap copper and scrap pure aluminum is particularly careful. To increase the output value, pure aluminum scraps such as scrap aluminum wire, etc., are the raw materials for adjusting the composition in the smelting of recycled aluminum. The separated aluminum scrap is mixed and generally no longer subdivided.
At present, the pretreatment of domestic waste aluminum has not been mechanized and automated, mainly relying on cheap labor. The tools used are magnets and steel foils. Based on experience, this sorting method has low efficiency, poor quality and high cost. In addition, most of the scrap non-ferrous metals such as copper in scrap aluminum are polluted, and manual sorting is difficult, which is far behind. It is necessary to research and promote advanced waste aluminum pretreatment technology.