Basic Oxygen Furnace (BOF) Slag is the primary non-metallic byproduct generated during the conversion of liquid pig iron into steel.

This slag is a complex mixture of calcium oxide from the flux and oxidized impurities, primarily silicon dioxide and iron oxides. While historically seen as waste, BOF slag possesses significant inherent cementitious properties and mechanical strength.

The industry focuses on making the most of its resources by using processed materials in valuable ways. This includes using them as aggregates for road construction and as substitutes for cement clinker. These efforts help support circular economy goals in the steel industry.