EMPLOYEE WAS CLEANING UP AREA ON EAST SIDE OF RAW MILL WHEN ANOTHER EMPLOYEE OPERATING A BOBCAT BACKED INTO HIM CAUSING INJURY TO LEFT KNEE. THE INJURED EMPLOYEE WAS STANDING IN THE BOBCAT OPE RATOR'S BLIND SPOT AND WAS AWARE OF THE BACK-UP ALARM, BUT DID NOT BECOME AWARE OF THE DISTANCE BETWEEN HIMSELF AND THE BOBCAT UNTIL IT HIT HIM.