How can you separate steel and aluminum?

Answer 1

Since steel cans are made of iron, they can usually be attracted magnetically

Since Aluminum is never magnetic, one method of separation would involve using a magnet. (An exception is "stainless steel" which is nonmagnetic, but it is much more expensive, and few if any cans are made from that.)

If magnetic separation is not possible, then another method would be to somehow separate by density. Aluminum cans, being much lighter than steel cans, and will tend to rise to the top, when tumbled repeatedly.

There are other properties, such as electrical conductivity, which differ between steel and aluminum, and these (in principle) could be exploited for separation, but using magnets (to attract the steel and not the aluminum) would seem to be the simplest and cheapest method.

If the cans are crushed and melted into a liquid (which also removes residual liquid and other contents), ore perhaps even heated into a gas, then the different melting points of Fe and Al could be used to separate the metals. A centrifuge might be used to separate materials of different densities (as is done, say, for enriching Uranium by removing the denser isotope, U238); however, that is probably not a cost-effective method for separating soda cans, and I would go with magnets instead!

Answer 2

Yes. Depending on how they are mixed. If they were melted together then it would be harder to seperate than if it is just pieces "mixed" together.

Answer 3

Use a magnet, steel is magnetic and aluminum isn't

Answer 4

Sodium Hydroxide will remove the aluminum from the copper, but the aluminum will need to be separated from the sodium hydroxide afterward.