폐굴패각 기반 CO2 포집 및 고순도 탄산칼슘 제조를 위한 소성？수화？탄산화 통합 공정

Abstract

Large quantities of oyster shells generated along Korea’s coastal regions are mostly treated as waste, even though their principal component is calcium carbonate (CaCO3), raising concerns over environmental impact and resource loss. This study proposes a resource-circulating process that converts oyster shells into a high-purity calcium oxide (CaO) source and subsequently produces high-purity calcium carbonate (CaCO3) through wet carbonation. The process integrates calcination, hydration, and carbonation in a continuous sequence. This integrated process is specifically designed so that the concentrated CO2 released during calcination is directly recycled into the subsequent carbonation step, enabling simultaneous CO2 capture and mineral carbonation without any external resource input. Calcining oyster shells at 850oC for 3 h resulted in the complete conversion of CaCO3 to high-purity CaO. The resulting calcium hydroxide (Ca(OH)2), produced during hydration, achieved a conversion close to the theoretical maximum (0.98？1.00 mol CO2 per mol CaO) upon reaction with CO2. pH monitoring and thermogravimetric analysis confirmed changes in product purity during the reaction, showing that a lower final pH increased CaCO3 purity, reaching over 91% at pH 7？8. X-ray diffraction indicated that calcite remained the dominant crystalline phase throughout the reaction period, with no phase transitions observed over time. These findings demonstrate that the integrated carbonation process based on oyster shells is a highly efficient route to achieving both resource circularity and carbon neutrality, providing foundational data for future industrial applications.