Harnessing the heat and material potential in steel slag to decarbonize China’s steel industry

Abstract The steel industry generates hundreds of millions of tons of steel slag (SS), with < 30% recycled in China due to its recalcitrant properties. Herein, we introduce a co-processing approach, modifying the molten SS with low-cost blast furnace slag (BFS) and sands to recover heat and produce cementitious materials. Such modification reduces SS viscosity by 83% (0.5 Pa·s) and free CaO to < 2%, enabling 75% thermal recovery efficiency (50% higher than conventional methods). Moreover, the final slag beads are nearly 100% glassy, suitable for cement production. Energy-economic assessment confirms its carbon-negative nature with heat and material potential being fully exploited. Scaling this technology across Chinese steel plants could yield $8.7 billion annual revenue and reduce 82 Mt CO 2 emissions (9.4% sectoral total) through heat reuse and clinker substitution. This work provides a potential pathway to the “hard-to-use” SS waste streams and advances the circular economy in China’s metallurgical industry.