Slag Detection System Based on Infrared Thermography in Steelmaking Industry

When liquid steel is tapped from a basic oxygen furnace (BOF), it is essential to minimize the quantity of slag carry-over, because the high level slag may result in the oxidation and the phosphorus reversion during the secondary metallurgy process. The system with the infrared thermal camera is widely used to detect the slag. However, two problems still exist. The first problem is the tracking of tapping stream. The second problem is to automatically discriminate between the slag and the steel according to their different infrared emissivities. In this paper, a system used to inspect the slag content is designed. A method that can quickly identify and track the tapping stream is proposed to only measure slag from the area identified as the stream. This reduces any errors caused by background heat sources in the field of view. A method to discriminate between the slag and steel is also proposed. Experimental results prove that the quantity of slag carry-over is decreased with using the system.