Alminium alloy scraps recycling has environmental and economic benefits. Compared to the other high volume materials, production of aluminium products from recycled scrap material requires 90-95% less energy than the production of primary aluminium. With these energy and cost savings in mind, many producers now have targets of increasing their usage of secondary materials. But, accumulation of unwanted elements is a growing problem in all recycled materials streams. Thus, the separation of tramp elements of aluminium alloy scraps is an important point to get pure metal in refining and recycling. Some researchers had already reported the physical separation process and chemical separation process. But, there are few papers of separation technology based on the metallurgical processing in semisolid state. The research of Rheorefining was begun by R. Mehrabian et al. in the 1974. This method was succeeded by Ichikawa et al. in 1997. In that method, aluminium scraps were heated and kept at the solid/liquid coexisting state and liquid impurities were separated through the porous filters. Even though significant amount of the impurities could be separated, that method was taken for long time to extract the liquid impurities component. Recently, S. Sugiyama et al. has begun the backward extrusion method to separate the pure aluminium and tramp elements in the semisolid condition. In this study, this backward extrusion method was proceeded to know the exact mechanism of separation of high purity of aluminium and tramp elements. 7N01 and 7075 aluminium alloys were selected for the refining trials. As the results of optical microscopic, hardness testing and EPMA analysis, it was confirmed that tramp elements were included in the extruded part and high purity of aluminium was in the unextruded part.
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