The machinery we build cleans steel by throwing steel BB's at over 250 feet per second in massive quantities (250 to 2200 pounds per minute). The abrasive is thrown by wheel that looks like a fan wheel, except the blades are turned 90 degrees to the face of the wheel. I know from modeling experiments, the abrasive being thrown moves in waves. It would be very cool looking to watch the actual steel piece go from knarly and rusted to clean and shiny.