SEPARATOR ATTENDENT WAS IN THE CONCENTRATOR SOUTH TRUCK AISLE. HE APPROACHED A 6 1/2"" DIAMETER X20' HOSE THAT WAS SUSPENDED BY AN OVERHEAD CRANE. THE GROUND MAN HAD HIM BACK AWAY FROM THE LIFT . HE BACKED AWAY, THEN RE-APPROACHED JUST AS PIPE JUST AS A COUPLING LET LOOSE BETWEEN 2 SECTIONS OF HOSE. A 10' SECTION FOLDED OVER AND HIT ATTENDENT ON THE HARD HAT. SUTURES/CONCUSSION.