Beer Kegs typically have the name of the beer company located somewhere on the beer keg.
When I bought my house I found a few beer kegs in the basement and decided to try and sell them to the scrap yard but they wouldn't take them and said they needed to be returned to the beer company.
I couldn't find the beer company so I gave them away to someone who I guess was gonna make gasoline tanks out of them for something.
Usually if you take them to the beer company you should get a deposit back on the beer Keg.
You might find a scrap yard that will take the beer kegs but most times you won't as it's illegal for scrap yard to take beer kegs which is what the scrap yard here told me.
I guess you could try cutting the beer kegs up and sell them in pieces and then they would accept them.