I don't recognize the copper part that broke off on yours. I doubt that JB Weld will work, unless minimal forces, and if so it probably wouldn't have broken. Not an expert, but I think the way to attach copper to steel is by "brazing". Solder can sometimes stick to steel, but has worked for me only on galvanized steel. It appears that two flat-head screws secure the piece, so the spot brazes were probably just for initial positioning and not required to secure it.
