Aluminum can recycling contamination problem

General principle — 6000 vs 5000 series alloy mixing forces downgrading. Turbine blade alloys spec'd virgin-only.

So recycling is not always easy. There are more sophisticated concerns. You have to grade your scrap — you can't mix 6000-series with 5000-series because of the different alloy content. You usually end up downgrading the alloy from some of your better stuff. In some critical applications, like turbine blade alloys, the spec will say you must use virgin material. You can't use recycled because they don't know what's going to be in the recycle. The point is, we're going to be using more and more recycle in the future, a smaller fraction of virgin material, because we have this tremendous resource out there of scrap coming back. We don't have that for certain materials like concrete, because we don't recycle concrete, which is a big problem we'll talk about later.

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