Abstract
Abstract: Mineral carbonation has garnered interest as a way of permanently fixing carbon dioxide Due to the benefits of permanent storage and abundant mineral resources, mineral carbonation is one of the most effective strategies for sequestering CO2. The combination of mineral processing for primary metal recovery and mineral carbonation of tailings for carbon sequestration is an emerging field of study with the potential to minimize carbon sequestration costs as the material is already ground.
A detailed study of low-pressure, high-temperature, gas–solid carbonation of ultramafic tailings in a dry environment was carried out. The carbonation extent of the tailings primarily containing serpentine has studied a function of temperature (300-900 oC), CO2 partial pressure (0.25-0.9 atm), and thermal preconditioning. The incongruent CO2 van der Waals molecular diameters with the octahedral-tetrahedral lattice constants of serpentine were used to explain the mild carbonation reactivity. It was determined that serpentine requires a thermal pre-treatment step to remove hydroxyl groups, resulting in the chemical transformation to pseudo-forsterite, a mineral composed of isolated SiO4 tetrahedra linked by octahedrally coordinated magnesium ions. The heat treatment above 850 oC is adequate to remove chemically bound water from the lattice. Particles with a diameter < 34 (μm) are desirable, and thermally treated serpentine at 850 oC for 2.30 hours reached 65% CO2 storage capacity.
Keywords: mineral carbonation (MC): particle size, thermogravimetry, thermal-treatment, serpentine.