A review in calcium carbide slag utilization for carbonation: from methods to applications

Global CO2 emissions, exceeding 40 billion tonnes annually, drive critical ecological challenges, necessitating effective mitigation strategies like carbon capture, utilization, and storage (CCUS). CO2 mineralization, a promising CCUS pathway, utilizes alkali-rich industrial wastes such as carbide slag (CS) to form stable carbonate minerals, ensuring permanent CO2 sequestration with minimal leakage risks. CS, primarily composed of Ca(OH)2, offers high alkalinity and calcium content, making it an ideal precursor for CO2 mineralization. Various carbonation methods, including direct, indirect and advanced techniques, could produce construction materials, high-value nano-calcium carbonates and energy storage solutions. Operational parameters such as temperature, concentration, humidity, and additives significantly influence carbonation efficiency and product properties. Direct carbonation yields CaCO3 suitable for large-scale industrial uses, while indirect and advanced methods enhance product purity and functionality for specialized applications. This integration sequesters CO2 while producing valuable by-products, thereby enhancing economic viability. This article provides a comprehensive analysis of CS carbonation mechanisms, methods, and applications, emphasizing the interplay between process parameters and product outcomes to optimize sustainable CO2 management and material innovation.