Abstract: Rotary furnace and preheater structure, wherein a billet is heated on an enclosed preheat conveyor where waste gases from the rotary hearth furnace preheat the billet counter to the billet travel direction. The preheated billet is inserted into the rotary hearth furnace wherein combustion gases, exiting from burners mounted in the furnace roof or sidewalls, flow counter to the hearth rotation direction and exit into the enclosed preheat conveyor. A baffle, depending from the stationary furnace roof, controls combustion gas movement counter to the billet travel direction in the furnace, and forces the combustion gases out of the furnace through a flue communicating with the preheat conveyor. A source of aspiration is provided to communicate with the preheat conveyor, and thus to facilitate combustion gas movement therethrough.