Conceptual evaluation of an integrated CCU technology based on Na-salts pH swing mineral carbonation

Giuseppe Bagnato, Aimaro Sanna*

*Corresponding author for this work

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Abstract

This work proposes an alternative indirect pH swing CO2 Capture and Storage by Mineral Carbonation (CCSM) process in order to decrease the energy intensive salts regeneration. In the proposed process, NaHSO4 is used to extract Mg from the mineral ore, which is then carbonated after a pH swing step. The remaining Na2SO4 is then separated from the carbonation solution taking advantage of its low solubility at temperatures close to 0 °C and then regenerated to NaOH and NaHSO4 in three stages. The integrated process that uses both Mg-rich silicates and inorganic wastes, was experimentally proved, and their energy consumption calculated. The final CO2 sequestration capacity was of 77.4% with enhanced recovery of metals in the pH swing step, which could offset the CCSM by about $50/t CO2. The final regeneration step showed a 55% conversion of Na2CO3 to CaCO3 at 120 °C under 3 bar and the conversion rate could be improved further by optimization. The energy consumption estimation without optimisation indicated that the sodium-based process would require about 19.6 GJ/tCO2, which at this stage of development is larger than the optimised Åbo Akademi process (12-15.5 GJ/tCO2), but considerably lower than the University of Nottingham's process (30 GJ/tCO2).

Original languageEnglish
Article number102286
JournalJournal of CO2 Utilization
Volume66
Early online date27 Oct 2022
DOIs
Publication statusPublished - Dec 2022

Keywords

  • Applied energy
  • CCS
  • CO2 fixation
  • Mineral carbonation
  • Sodium salts

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Process Chemistry and Technology

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