• 목록

Integrated valorization of blast furnace slag for dual production of zeolite X and CaCO3

Abstact

The sustainable management of blast furnace slag (BFS), a major steelmaking by-product, remains a global challenge owing to the lack of effective recycling pathways that enable the selective recovery of calcium, silicon, and aluminum for conversion into high-value functional materials. This study introduces an integrated closed-loop system that enables the dual production of Zeolite X and calcium carbonate (CaCO3) through an acetic-acid-based process. Calcium is selectively leached from BFS under acidic conditions, and the remaining silicon–aluminum matrix serves as a precursor for zeolite crystallization. Unlike conventional methods in which the calcium-rich leachate is discarded after zeolite synthesis, the proposed framework reuses the same leachate for CO2 mineralization, eliminating secondary waste and minimizing reagent consumption. Through an integrated evaluation of zeolite and calcium carbonate synthesis, we identified leaching with 1.0 M acetic acid at 70°C as the optimal condition that enabled—selective calcium removal, the formation of high-crystallinity faujasite-type Zeolite X, and the controllable CaCO₃ production via indirect carbonation. The integrated pathway achieves complete utilization of BFS constituents: The residual by-products yield highly crystalline Zeolite X with well-developed porous structures, whereas the recovered leachate produces phase-tunable CaCO3. This dual valorization simultaneously converts industrial by-products and captured CO2 into two functional, high-value materials. The proposed closed-loop framework offers a sustainable and scalable route that couples carbon sequestration with waste upcycling, supporting carbon-neutral and circular manufacturing in the steel industry.