
55Aluminum Recycling Economics
valuable grade is new alloy 6061 scrap, which has the advantage of being new, but
may not have the consistent shape and size of old wheels. The lowest-valued scrap
is mixed-alloy, high-grade turnings (Figure 4.4), which cannot be directly remelted,
contain oil or lubricant, have a high surface/volume ratio, and may have more cop-
per than most aluminum alloys can tolerate. The sorting technologies described in
the next chapter will not be useful for upgrading this material, either. As a result, its
usefulness is limited. In general, the lowest-valued scrap grades tend to be old rather
than new, mixed rather than ...