(13h) Experimental Investigation of a Dry Slag Granulation Unit Using a Rotating Disc

Crude steel production has increased significantly over the past decade. Blast furnace slag is one of the major by-products from the steel industries. The molten slag exits the blast furnace at 1500-1700 K. At present, this molten slag from the blast furnace is quenched with water. Upon cooling, the molten slag solidifies to form a glassy phase that can be used as an alternate to Portland cement. The major drawbacks in the existing methodology of treating BF slag are (i) Heat from BF slag is not recovered (ii) consumption of water for quenching is very high.

There is significant scope to improve the energy efficiency of the steel manufacturing sector by recovering high quality energy from the blast furnace slag and reducing the consumption of water using the dry slag granulation technology. In this work, we have performed an experimental analysis on a dry slag granulation unit using rosin-paraffin wax mixture (liquid mixture in 4:1 ratio based on weight) as an analogue to BF slag. A spinning disc was employed to atomize the molten liquid mixture in the form of fine droplets under the action of centrifugal force. The focus is on analysing the effect of temperature of rosin-paraffin wax mixture and the material of the spinning disc on average particle size. Aluminium, glass and wood are chosen as the disc material. The range of operating conditions in terms of dimensionless numbers is analysed to demarcate the particle forming regime and the fibre forming regime. The effect of diameter and rotational speed of the disc and molten liquid flow rate on the average diameter of the granules formed is studied for the chosen materials. Scale up details of the existing setup will also be highlighted based on a correlation relating the dimensionless numbers and particle diameter.