Cutting open propane tanks is safe if done properly and as long as the propane is no longer in the tank.
Never try cutting open a propane tank with propane in it and without the valve being open and vented.
Also fill the propane tank with water and drill a few holes in the top of an empty propane tank and fill with water and allow it to vent.
I've cut open propane tanks by drilling holes in the top and allowing the propane smell to dissipate and vent out over a few days.
After filling it with water then I used a grinder with a cut off disc to cut it open.
Never had an issue but you just have to be careful and if you're not comfortable with a grinder you can use a Sawzall without the sparks.
Ace Hardware does take old propane tanks for exchange for a full propane tank.
Simply leave your old propane tank outside near the propane tanks and then go inside and let them know that you want to exchange your old propane tank for a new one.
Then pay the cost of the exchange propane tank and propane and the old propane tank will be picked up by the propane company.
Some Ace Hardware stores may also take an old propane tank that you simply want to get rid of and then send it off to the propane company.
You can also recycle old propane tanks by.
Contacting a propane supplier who can pump out the tank and ensure it's safe to transport.
Exchanging the tank.
You can trade in your old tank for a refilled one at many propane refill locations.
Dropping it off at a propane exchange company.
Some propane exchange companies, like Blue Rhino, will recycle your tank for free.
Taking it to a hazardous waste disposal site.
You can contact your local hazardous waste disposal site to see if they accept propane tanks.
Contacting your local public works department.
You can contact your local public works department to see if they accept propane tanks.
Taking it to a permanent HHW collection center.
You can check with your local household hazardous waste collection center to see if they accept propane tank.
If the propane tank is empty and you can safely cut the propane tank open you can cut the propane tank open and then a scrap yard will take it.
However the propane tank should be emptied and vented open and even filled with water before cutting it open for safety.
If you're unsure of how to safely cut a propane tank open then do not do it and let someone who does do the cutting.
The best way to recycle the propane tank is to exchange it for a new one or see if the propane exchange will simply take the propane tank even if you don't want to buy a new tank of propane.
If the propane tank is still good then it can be refilled by a propane supplier.