Design and Operation of Dry Slag Granulation Pilot Plant

CSIRO has been working on a dry granulation process, integrated with heat recovery, since 2002. It involves a rotary disc that atomizes molten slag to produce liquid droplets, which are rapidly quenched to become solid granules. The hot granules are fed to a counter-current moving packed bed heat exchanger, where they are further cooled and finally discharged at close to ambient temperature. Air is used in both units to recover the heat. Development has proceeded through proof-of-concept tests, a prototype and now a pilot plant, capable of processing 100 kg/min of slag. Extensive CFD modeling was used to predict disc and granulator performance as a function of design and operating parameters. Experimental results on the dry slag granulator pilot plant have demonstrated that the process can effectively produce glassy slag granules from molten iron blast furnace slag, and recover significant heat, and that the CFD model can be used to predict process performance. Work continues to scale-up the process and extend the operation to other metallurgical materials, such as non-ferrous slags and mattes.