Recycling aluminum uses about 95% less energy than making new one from bauxite ore, which compares very favorably with other types of recycling. For example, recycled plastic requires 70% less energy and paper uses about 40% less. That's pretty good, though as we've said many times, it's always better to just use less stuff to begin with, to find ways to reuse what you already have, or repair it, etc (the 7 Rs). But even if we apply these principles, we all use stuff anyway, and it's better for these raw materials to be recycled into something useful than to end up in a landfill.
To go back to aluminum, the fact that recycling it saves so much energy combined with the fact that it can be recycled almost an infinite number of times (it doesn't degrade like paper or plastic) mean that it possible to imagine a day when we don't even have to make new, energy-intensive aluminum anymore. The amount being recycled would meet the demand from industry to make new things.
The BBC writes:
Although Aluminium is the third most abundant element in the earth's crust, it was not isolated until 1825, and remained so scarce that it was valued more highly than silver for decades. [...] Bauxite is found across the globe, and mining it is the easy part. Far trickier is extracting the metal. It was not until 1886 that a Frenchman and an American both cracked it.
You have to melt the bauxite in another mineral called cryolite, and then pass an electric current through it, separating the oxygen atoms from the aluminium. It takes four tonnes of bauxite to produce one tonne of aluminium.
The process is highly energy-intensive and therefore expensive. [...]
Once you have the metal, you can re-use it again and again, almost indefinitely.
"It is one of the few materials that is genuinely 100% recyclable," [Nick Madden, who is responsible for buying raw metal for Novelis, the world's biggest manufacturer of rolled aluminium sheets,] says.
In theory, a day may come when we have mined all we need, and we can just keep re-using what we already have.
Right now demand for aluminum is climbing, in good part because automakers are putting more and more of it into their vehicles because it's lighter than steel and thus leads to better energy efficiency. Maybe someday that will be replaced, or augmented, with carbon fiber -- it's still too expensive for most usages now, but prices could fall significantly. After all, it's not like carbon is scarce...