Coleman Propane Cylinders will fit a torch such as the Bernzomatic Torch used for soldering with.
The Coleman Propane Cylinders are cheaper and fit the handheld torches just fine.
A Coleman Propane Cylinder will last for 1.5 hours to 2 hours depending on the size of the flame you have.
The lower the heat setting you use on the torch or the stove etc then the longer the propane will last but if you have the heat setting up high and have the propane burning full blast then the propane will be used up much quicker.
I usually get 2 hours of burn time from the Coleman Propane Cylinders unless I turn the heat up more then it last about 1 hour and 30 minutes.
To dispose of Coleman propane cylinders you should check with your local landfill and see if they have a hazardous waste disposal place at the landfill.
Also some communities will have a way to dispose of hazardous waste through a trailer or a pickup day or drop off place to drop off and dispose of hazardous waste including small propane cylinders.
You could also use a hacksaw and cut open the old empty Coleman propane cylinders and then place them with some other metal to sell to a scrap metal yard.
This is what I do with them.
I don't use a lot of them but when I do have empty 1 lb propane cylinders I will cut them open with a hacksaw and place them in a 55 gallon barrel with some other scrap metal.
Then when I have enough scrap metal to sell I take it to the scrap metal yard.
Also there's an adapter you can buy that you can install on the Coleman propane cylinders and refill them with a big propane tank.
So that's another option and the propane will be cheaper that way as well.