Energy-environment-economy evaluations of commercial scale systems for blast furnace slag treatment: Dry slag granulation vs. water quenching

The high-temperature blast furnace slag is conventionally treated by water quenching (WQ) method with enormous waste heat unrecovered. To address this issue, dry slag granulation (DSG) technology has been proposed to recover the waste heat from molten slag. Before commercial implementation, the sustainability and feasibility of the DSG should be well assessed. In this study, life cycle assessment (LCA) is conducted on a designed DSG prototype system in commercial scale. The environmental sustainability and economic benefit of DSG are evaluated and compared with the WQ systems. The LCA results reveal that the DSG can potentially reduce the energy and resource consumptions by 150 kg-coal-eq/t-slag and 1547 kg/t-slag, respectively. The analysis on environment impact also clarifies that the DSG is an environmentally friendly method for slag treatment. Furthermore, the DSG method represents a possibility to recover the heat from high-temperature blast furnace slag and turn it into a valuable material with a profit of 92.9$/t-slag.