Mineral carbonation: Kinetic study of olivine dissolution and carbonateprecipitation

摘要

Aqueous mineral carbonation is a process of converting carbon dioxide into solid carbonates and can be exploited to store CO_2 as part of a CO_2 capture and storage system. In this study, mineral carbonation using olivine as the source mineral was investigated. The overall reaction of forsterite (end-member of olivine) is: Mg_2SiO_4 + 2CO_2 <=> 2MgCO_3 + SiO_2 (ΔH = - 89 KJ mol~(-1) CO_2) (1) The process can be split up in three main elementary phenomena that control it kinetically: dissolution of olivine, dissolution of CO_2, and magnesium carbonate precipitation. In-situ Raman analysis was applied for monitoring the CO_2 dissolution and speciation. Dissolution rates of olivine at different pH values and temperatures are presented. Mg-carbonate precipitation was studied in the H_2O-CO_2-Na_2CO_3-MgCl_2 system; the induction time was measured with FBRM and a turbidity meter, and precipitated solids were characterized using X-ray diffraction and SEM.