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Carbonation of chrysotile mining residues (CMR) was studied to expose the role of residue size and mineralogy, gas composition, liquid saturation and watering schemes in saturation-controlled porous beds. CO₂ uptake dynamics and evolution of carbonating residue were monitored in situ in terms of gaseous CO₂ absorbed and relative humidity, bed liquid saturation, electrical conductivity, pore-water pH, and pressure drop. CO₂ uptake was contributed both by facile carbonation of chrysotile fines and “domestic” brucite, and slow-paced carbonation of coarser magnesium silicate particles. Chrysotile carbonation was a function of fiber length while inhibited lizardite carbonation was indirectly observed. A CO₂-lean carbonation regime was identified where CO₂ uptake increased linearly with the CO₂ fraction. This enabled extrapolating at very low CO₂ gas contents to assess CMR carbonation under natural …