Thermomechanical Treatments for the Separation of Cast and Wrought Aluminum

"The increased penetration of wrought aluminum into the automotive market is stimulating a need to separate wrought aluminum from cast aluminum because of: a) the additional value of scrap wrought alloys and b) the increase in the total amount of aluminum automotive scrap will outstrip the demands of secondary aluminum foundry industry. The availability of clean fractions of wrought and cast aluminum and incidentally, a clean cast magnesium fraction will allow increased recycling of aluminum used in the automotive industry.Hot crushing has been tested previously and proposed as a means to separate cast from wrought alunrinum product. The underlying concept is that when a mixture of cast and wrought aluminum is thermally processed and then subjected to crushing action, differences in toughness between wrought and cast aluminum alloys will become more pronounced. Hence, it should be possible for conditions can be established such that the cast material fragments, while the wrought material, having lost much less of its toughness, merely deforms. The two types of product could then be separated by simple sizing methods.In this paper we report on the testing of this concept. We were unable to replicate the results which originally demonstrated proof of concept. Possible reasons for this are discussed, as well as the possibility that the original results may not be as desirable as the current results for subsequent sorting."