Recycling Small Propane Cylinders

My family got a new camping stove before our recent camping trips to Silver Falls State Park. While purchasing it we noticed that the small green Coleman propane canisters are now recyclable with a little green plastic "key".

What about our older cylinders? I called the local recycling company and they assured me that any fully drained canister could be put into the recycling bin. The plastic "key" is merely an extra assurance to a recycling company that the cylinder is fully drained: it drains the last of the propane, but no more or less effectively than through other methods.

In fact, steel is valuable enough that they were pleased to have been asked the question!