If a salvage yard won't take it, you may be stuck with a landfill. Recently I had to take a 45' house trailer frame (just the frame and flooring left) to a landfill. They charged by the pound and it cost me $260.
The same location takes used cars and trucks for only $25 ea, but those they sell those to a crusher/recycler. They said the long frame with the wooden flooring was too labor intensive to recycle so it had to be buried and therefore I paid for it by the pound.
Bill