Granulation and Heat Recovery from Metallurgical Slags

Metallurgical slags are produced at a massive rate of over 750 Mt/year, and carry a thermal energy equivalent to 40 Mt/year of coal. The potential mineral and thermal energy values of slags are in the order of $22 b and $3–6 b per year. Such attractive figures, together with tightening legislation on disposal of slag and the carbon footprint associated with the loss of mineral and energy values of slags have created a significant thrust in the past decade to develop sustainable approaches for full utilization of slag and its waste heat. As a result of extensive R&D in this area, the slag-processing technologies are slowly converging around dry granulation combined with heat recovery. In this paper, the slag granulation and heat recovery options are reviewed and given a critical evaluation, aiming to provide a basis for future directions in slag handling.