On Tue, 29 Oct 2013 17:37:54 -0700 (PDT), "
wrote:

Keep it hanging up on a nail in your garage. It is cheap insurance that neither of your new matched springs will fail, because you could use the spare as a replacement in the event of a break and not be trapped without a spring.

Otherwise, put it out at the curb on garbage day and the recyclers that pick up scrap metal will probably take it. Or, if there is a place that buys scrap metal handy, take it there.

I took a fire-damaged stove to the city recycling place, and before I
could get up to the gate, a guy stopped me. He was waiting there just
for people like me. Maybe he was even willing to pay me something for
it, but since I was going to dispose of it, I just gave it to him and
he put it in his pickup and later sold it to a metal recycler.

I sold a sorted pick-up load of copper, aluminum, and steel scrap to a
junk yard a couple years ago, but I don't remember how much they paid
for any of them.