Experimental investigation on ligament formation for molten slag granulation

During the dry granulation for molten blast furnace slag, rotary cup is used to atomize the molten slag. In this study, the mechanism of ligament formation for molten slag granulation was investigated. The results indicated that the transition equations from direct drop formation to ligament formation and ligament formation to sheet formation, obtained from glycerol/water mixture, can identify the type of disintegration for molten blast furnace slag granulation. Due to short wavelength of dilational wave along molten slag ligaments, the diameter of slag particles decreased with an increase in angular speed, and more and more slag particles were far away from the center of rotary cup. The slag particles diameter decreased with an increase in rotary cup diameter. The empirical equation can be used to predict the diameter of slag particles obtained by ligament formation for molten slag granulation at high angular speed. Because of slight change in viscosity and surface tension when the temperature of molten slag was over than 1300 °C, there was no change in diameter and mass fraction of slag particles with an increase in molten slag temperature. All the results could provide guidance for the design of industrial plant for molten blast furnace slag granulation.