EMPLOYEE WAS CLEANING UP USING A SKID STEER. W/THE BUCKET ON THE GROUND & CLEANING UP, SAND STRUCK SOME TYPE OF METAL OBJECT & STOPPED SKID STEER INSTANTLY. THE OPERATOR WAS WEARING HIS SEAT BELT & HARD HAT. HIS HEAD MOVED FORWARD, THE HARD HAT TIPPED FORWARD & HIT THE LIP OF THE HARD HAT CUT THE NOSE AREA REQUIRING 3 STITCHES.