New Techniques to Detect the Suitable Time to Close the Tap Hole of a Blast Furnace

The closing of a BF tap hole, as a final end to an optimum pig iron and slag tapping contained in the hearth, is an operation that requires the plant operator's complex background to recognize the instant in which the tap hole must be closed; this way avoiding dangerous phenomena relating to whistlinga. In this paper, two systems are described – which may act concurrently – of advisement to the plant's operator in order to warn him of when he must close the tap hole. One of them is based in the processing of the EMF probe signals, which measure the electromotive force between two points of the hearth shell. These probes are welded to the BF shell under study and are located on top and underneath the respective tap hole. The second system uses image treatment of pig iron and slag flow casting coming out of the tap hole in this hostile environment. In this paper are described two BF plant's operator advisement systems in order to warn him when he must begin to close the tap hole. One of them is based in the EMF probe signals processing, and the second one, using the image treatment of hot metal and slag while are flowing by the tap hole. Both systems may act concurrently