Recycling Options for Steel Working Slag and Upcycling Perspectives

The steel working industry is energy intensive. Even a byproduct like molten slag has a high specific energy (1.5°GJ/t). Most of this energy is still dissipated during cooling-down the slag despite a lot of processes for heat recovery that have been developed. Also there are some concepts to use slag more effective by material recovery. Here we suggest an upcycling process to produce foamed slag. This approach combines energy and material recovery by using minerals containing carbonates or hydroxides as foaming agent. As foamed glassy materials capture the market for construction they might pave the way towards an economically attractive upcycling of steelwork slag.