EE WAS STANDING ON CONVEYOR #5 TRYING TO REMOVE THE ROCK THAT WAS WEDGED IN THE BACK FEEDER OF THE SECONDARY TUNNEL. HE WAS REMOVEING THE ROCK THAT WAS WEDGED IN THE BACK FEEDER WITH A JACK HA MMER. WHEN HE TURNED, HE SLIPPED ON LOOSE ROCKS, CAUSING HIS KNEE TO TWIST.