EE ATTEMPTED TO ENTER A MANLIFT WHICH WAS PARKED UNDER A CRUSHER FEED BIN. OTHER WORKERS WERE CUTTING A PIECE OF 1/2"" SHEET STEEL TO MODIFY THE CRUSHER FEED BIN. HE WAS NOT WEARING A REQUIRED HARD HAT. WHEN HE WALKED UNDER THE CRUSHER FEED BIN, A PIECE OF STEEL FELL, STRIKING THE LEFT SIDE OF HIS SCALP. HE HAD 5 STITCHES AND WAS RELEASED TO WORK IMMEDIATELY.