alt Hacker NewsI've wondered about this because I've heard the same thing from my partner - in Engineering school in Spain, she was told that waste aluminium as a building material should be avoided because it was so expensive to recycle. But we recycle aluminium here in New Zealand - perhaps it's something to do with being able to use green energy at night (New Zealand has abundant hydro power)?
Al uses a lot of energy. Recycling is much less than uses to get it from mining.
I've never heard of anyone using aluminum for a building (though I'm sure it has been done) - the properties in general make it a poor choice (see a real meteorologist for details - alloy matters and there are many choices). Al is commonly used for the skin of a building, but not the structural parts.
Al is commonly made where energy is cheap (generally renewable energy!) and then transported around the world. I have no idea what is in Spain or New Zealand, but I'd expect someone in Spain is making things with Al, and they in turn will be glad to recycle anything you can get to them.