In my complex there are two recycling bins by the dumpster, one for newspapers and one for “glass containers, plastic bottles and aluminum cans.” I was about to put a soup can in the latter when I realized it’s steel, not aluminum. But why is that? (And why is there no recycling bin for steel cans?)
Soda cans can be made of very thin aluminum because they contain high pressure which helps keep the can in shape. Food cans, on the other hand, have no support other than their own strength, which is why they are not only made of heavier steel, but also corrugated to provide additional structural support.
I wonder if it has anything to do with the potential for some foods to break down aluminum. Ketchup, for instance, will eventually dissolve aluminum foil. Strangely, I would have figured that soda is one of the most acidic food items around, so there must be something I am missing.
ETA: I see that it is structural and not chemical, based on QED’s respons.
Well, partially, anyway. I’m sure there are other reasons as well; noncarbonated beverages are also served in cans; I can’t immediately think of a reason why that should be–low compressibility of water, perhaps? To your other point, as far as I’m aware, all metal food and beverage containers are coated inside to prevent corrosion and contamination.
How much pressure is it, really? I mean, when I open a soda, maybe I get a little “psst” or maybe nothing at all, if the can hasn’t been shaken.
Looks like anywhere between ~30 and ~55 PSI, depending on your sources. This page also gives another explanation for stronger steel cans for food: apparently the pasteurization process used for sterilization of many canned foods creates internal pressures up to around 90 PSI.
Cost. Aluminum is more expensive than steel per gram, but it’s easier to make into thin foil. It’s worth it for pop cans because you can make the can much thinner when the contents are under pressure.
You’re going to have to ask your town this question. In fact, why don’t I ask your town this question?
Hey Tampa, what about the steel cans?
My town does steel cans commingled with glass plastic and aluminum, but steel is so easy to separate, it makes sense to snap it up with the rest of the garbage, so you don’t miss any.
You do realize the aluminum is coated on the inside right?
Here is a fun way of removing the Aluminum yet retaining the plastic inside.
http://www.metacafe.com/watch/746435/the_naked_soda_can/
Osip
Of course I didn’t realize. I said quite clearly that I must be missing something based on the evidence. I did know Keystone beer was coated for that bottle like flavor in a can. 
Even in municipalities without a specific steel can recycling program, recycling rates are above 50%, mainly due to post-burn magnetic separation. Overall in the US the recycling rate for tin cans is at about 62%