• • Carbide slag (CS) contains CaO as the primary oxide, with Ca predominantly in Ca(OH)2 and CaCO3 forms; its density ranges 2.5–3.0 g/cm³, and its high alkalinity (pH>13) necessitates treatment.
• • Global CS production exceeds 40 million tonnes annually, yet utilization in China remains below 40%, primarily as cement raw material, underscoring the need for alternative valorization routes.
• • Direct carbonation and indirect ammonium salt leaching-carbonation are the main pathways; process parameter regulation, amino acid modification, and multi-solid waste coordination improve reaction efficiency and product performance.
• • The technology enables controlled synthesis of high-value calcium carbonate products, with derived lightweight fillers and low-carbon cementitious materials offering dual environmental and economic benefits.