Was there Artillery Shell Recycling in WW2?

Was there Artillery Shell Recycling in WW2?
There is another Colonel Question, this time from Andrew:
"My question is as follows: Did the major powers in the European theater (US, UK, USSR, Germany) have standard operating procedures for recycling those piles of artillery shells we see in pictures from so many wars from WWI onward? Or was the metal just buried, or recycled or not recycled as a local commander saw fit?"