Chemical and Bioreductive Leaching of Laterites and Serpentinite Waste with Possible Reuse of Solid Residues for CO2 Adsorption

Experiments were conducted to evaluate domestic low-grade laterites and serpentinite waste as potential secondary sources of nickel and magnesium and to assess leaching residues for carbon dioxide adsorption. Solids were leached chemically using sulfuric acid, while bioreductive dissolution under anoxic conditions employed a consortium of microorganisms dominated by Sulfobacillus. The efficiency of laterite bioreduction was 26.81% for Ni and 63.92% for Mg. In the case of serpentinite, 20.54% Ni and 92.88% Mg were extracted. The chemical dissolution yielded 26.73% Ni and 61.37% Mg in the case of laterites and 16.20% Ni and 77.49% Mg for serpentinite waste. Specific surface area was analyzed during the processes, showing a systematic increase over time. Based on the changes in this parameter, a mathematical description of the process was proposed using a shrinking particle model (SPM). Except for laterite bioreduction, leaching was shown to be a two-stage process controlled by a chemical reaction. The serpentinite solid processed in the presence of microorganisms exhibited the highest surface area (267 m2/g) and a CO2 adsorption capacity of 19.9 cm3/g.