9th ECCC European Continuous Casting Conference – ECCC 2017

Research of Clogging in Continuous Casting Nozzles at KU Leuven M. Guo1*, Y. Vermeulen2, Rob Dekkers3, X. Guo4, Patrick Wollants1, and Bart Blanpain1 1Dept. of Materials Engineering, KU Leuven, 3001 Heverlee, Belgium 2 3 ROCKWOOL B.V. Industrieweg 15, Postbus 1160,The Netherlands 4Dept. of Mater. Sci. & Eng., TU Delft Mekelweg 2, 2628 CD Delft, The Netherlands *Corresponding author’s Tel: +32-16-321183, E-mail: muxing.guo@kuleuven.be The continuous casting process accounts for more than 90% of the world’s steel output and is considered to be a mature technology. However, a major problem of the process is nozzle clogging, which increases the frequency of operation disruptions to change nozzles or tundishes or even to stop casting, rising operating cost, lowering productivity and directly resulting in a variety of quality problems. Clogging is a complex problem which has received a great deal of past study. These are: (1) identification of the clogging type of its formation mechanisms, (2) clogging detection and (3) approaches/ways for clogging reduction. In this abstract, we highlight some of our results that have been achieved in the research of clogging in continuous casting nozzles at HiTemp Group of KU Leuven. These include the followings: (I) characterization of the clogged nozzle from industrial practice to quantify extent/amount of the clogging and the identify causes of clogging. A distinct relationship was found between the amount of clogging and the cast steel weight. No relation between the amount of clogging and the superheating of the steel nor the steel flow rate was noticed. It was concluded that in practice, a given nozzle clog is often a combination of two or more of the different mechanisms, such as the transport of oxides present in the steel to the nozzle wall, steel reoxidation within the nozzle, chemical reaction between the nozzle refractory and the steel and others. (II) laboratory investigation of the interactions between the nozzle refractory, clogging materials, steel and slag to understand the influence of the chemical composition of the refractory material on the chemical compatibility with liquid steel, inclusions and slag, for better nozzle material selection and steel cleanliness. An experimental laboratory procedure was optimised to simulate the interaction behaviour during continuous casting. Al2O3 was found to give satisfactory results, and therefore a Al2O3 plasma coated Al2O3 carbon material was also tested in the laboratory with good results. KEY WORDS: Continuous casting, Nozzle clogging, Inclusions, Refractory