Abstract: At approximately 1:23 p.m. on February 28, 2007, Employee #1 was working at a borate surface mine located in Boron, California. The mined material goes through numerous refining processes on its way to becoming the final product. One of the processes is a polishing filter operation, and it was at the BAP-FI-001 Filter "A" where the accident occurred. Employee #1 and a coworker, a trainee, were at the BAP-FI-001 "A" tank making repairs on a bracket and U-bolt. The bracket supports and holds in place a rod to which polishing filtration screens are attached. The screens and rod are enclosed in a horizontal steel tank. In normal operation, the tank fills with hot liquor at a pressure of 6 to 10 psi. Employee #1 had placed a 6-foot rolling stair platform in place at the bracket end of the tank. He loosened the nuts holding the U-bolt, but the bracket remained in place. He directed the trainee to hand him a small hammer to tap the bolt. The trainee complied and, looking down for a second, felt a hot liquid spilling on his back. He looked up to see that Employee #1 had been knocked off the platform and was lying face down in the spilled liquor. Apparently, the rod and bracket, under pressure, had shot out in excess of 10 feet. The trainee pulled Employee #1 from the hot liquor and checked to see if Employee #1 was conscious. Employee #1 was aware of things and bleeding from his face. His nose was fractured. The trainee summoned help. Assistance arrived and a rescue helicopter was summoned. Employee #1 was stabilized and transported by helicopter to Kern County Medical Center in Bakersfield. He was hospitalized, being held overnight for observation. Cal/OSHA has determined that the causes of the accident were not following shutdown/lockout procedures and not releasing pressure in the tank before attempting repairs.