If, as I suspect, this is a non-explosive dummy used for training loading crews, they would have been disposed of when no longer needed. As a non-explosive item that could have been as simple as placing in a trash dumpster, or perhaps sold off as scrap metal.
Of course, since it looks like something that might go “BOOM!” lots of people might get worried if they found it, so authorities would dispose of it. That can range from simply hauling it away, to using it as an excuse to do the full explosive ordnance disposal routine with x-rays, hauling to safe area and blasting it with an explosive charge to detonate it if there is anything explosive inside. Better safe than sorry, I guess, and if they practice on even inert objects they will be better prepared for a real explosive device.