EMPLOYEE WAS USING A WATER LANCE TO UNPLUG 2-1 PANT LEG ON #2 BAUXITE BIN. EMPLOYEE STATED THAT A PIECE OF SCALE BROKE, AND STRUCK THE TIP OF THE WATER LANCE, CAUSING HIS RIGHT ARM AND SHOULDER TO JERK IN A UPWARD MOTION. EMPLOYEE FELT A SHARP PAIN TO HIS RIGHT SHOULDER. EE Treated & released at plant medical facility. On followup visit of 11/2/09, EE ws placed on restricted duty