Valorizing inherent resources from waste streams for in-situ CO₂ capture and sequestration in the steel industry

The imperative need for decarbonization within the energy-intensive steel industry, a pivotal sector for meeting global warming mitigation targets, underscores the significance of deploying cost-effective CO₂ capture and sequestration (CCS) measures. The substantial external costs and resource consumption associated with traditional CCS methods present practical challenges. Here, we proposed a pragmatic strategy to integrate CCS into the steel industry through recycling inherent resources from steelmaking waste streams for in-situ CCS (ICCS). The composites prepared from blast furnace slag (BFS) and steel slag (SS) demonstrated the capacity to capture a maximum of 2.77 mol/kg of CO₂ from the simulated flowing flue gas at 75 °C, and the energy required could be sourced from steelmaking waste heat. Comprehensive characterizations revealed the evolution of phase compositions and pore structures in different BFS/SS-incorporated composites, providing insights into accelerating the carbonation by elevating temperatures and SS dosages. Notably, ICCS strategy was validated to offer significant potential in CO₂ emission reduction (up to −570.0 kg CO₂e/t) normalized by compressive strength of the conventional construction materials. Overall, ICCS strategy can minimize the external resource consumption and additional units for implementing collaborative waste recycling in the steel industry with significant environmental benefits.