Indirect mineral carbonation of natural asphalt extraction solid waste residue via pH and temperature control

This study investigated the recycling of solid waste residues from rock asphalt extraction via 5-hour calcination at 900 °C and indirect carbon mineralization. The calcined powder was first dissolved at 60 °C in 2 M CH3COOH, carbonized in NH4HCO3, and agitated at 1200 rpm in 2 M NaOH for 30 minutes at 30–60 °C and pH 12. The precipitated calcium carbonate (PCC) results are calcite (24.4–56.3 wt.%) and vaterite (75.6–3.7 wt.%), as confirmed by XRD analysis, carbonate FTIR spectra, and SEM images of prismatic calcite and spherical vaterite. This high-value PCC product has potential industrial applications, such as paper and plastics.