5 th International Slag Valorisation Symposium | Leuven | 03-05/04/2017 75 SURFACE TENSION STUDIES OF MOLTEN CaO-Al 2 O 3 JETS – OSCILLATING JET METHOD Luckman MUHMOOD 1 , Mirco WEGENER 2 , Shouyi SUN 3 , Alex DEEV 3 1 K J Somaiya College of Engineering, Vidyavihar, Mumbai, India 2 SOPAT GmbH, Berlin, Germany 3 CSIRO, Process Science and Engineering, Clayton, Australia luckman@somaiya.edu, mirco.wegener@alumni.tu-berlin.de, alex.deev@csiro.au, shouyi_sn@yahoo.com.au Introduction Blast furnace slag currently is being used as an additive in cement owing to its chemical and phase compatibility with the latter 1 . However, during actual processing, the slag is water-cooled using atomisation technique prior to its usage in cement. This not only consumes a tremendous amount of water (roughly 10 times the weight of slag) but also the slag temperature of approximately 1500°C goes unutilised. To tap into this energy potential, researchers have been working on various techniques for waste heat recovery from slags. This technique involves shearing the slag surface using an external force, predominantly centrifugal in nature viz: rotating disc or drum method 2-4 . The shearing force decides the size and shape of the droplets generated. On a fundamental viewpoint thermophysical property like surface tension, viscosity and density play a key role in deciding the shape of the jet and its break up into drops. The jet emanating from the rotating disc or drum can be physically equated to a jet generated from a nozzle tip. In order to understand the dynamics of the molten slag jet formation and break up, an experimental set up was designed and fabricated. Molten oxide jets were observed and the profile of the jet followed in detail. The surface tension of the oxide mixture can be obtained from the first three dip and swells of the liquid. The current work discusses on molten CaO-Al2O3 slag jets emanating from a graphite nozzle. Materials and Experimental set up High purity alumina and calcium carbonate were used as the starting materials for the experiments. The calcium carbonate was reduced to CaO by keeping the former in a muffle furnace maintained at 1373 K for 12 hours. Based on the calcia-alumina phase diagram, the composition was fixed to be close to the eutectic (51% Al2O3 -49% CaO) composition. The composition and melting point was verified chemically and optically using XRF and a horizontal furnace- camera assembly. Bulk quantity of the slag was prepared by repetitive melting and pouring of the slag – ensuring chemical homogeneity.