EMPLOYEE WAS HELPING STRING A NEW BELT ON THE SREENING CONVEYOR. EE HAD LEFT HAND ON THE RAIL OF THE CONVEYOR. THE CHAIN THEY WERE USING FLIFFED OFF THE 4X4 BAR AND HIT EE'S HAND. EE RECEIVED A BROKEN INDEX FINGER ON LEFT HAND FROM THE CHAIN AND 4X4 WOOD BLOCK. EE WAS TREATED AND RELEASED FROM HOSP.