CO2 sequestration by high pressure reaction with olivine in a rocking batch autoclave

- A tubular rocking batch autoclave has been used for CO2 sequestration.
- Large olivine particles have been carbonated at 175 °C, 100 bars in the autoclave.
- The solid phases have been characterized by TGA and dilute HCl dissolution.
- Carbonates and silica particles are simply be separated by olivine settling.

Industrial olivine has been carbonated at 175 °C, 100 bars in a mixture of supercritical CO2 and an aqueous solution, for 30 min to 12 h in a rocking batch autoclave. Simple settling of the solids recovered after the reaction led to a “fines” fraction and a coarser (residue) fraction. The carbonation extent of olivine was limited to 30% mainly because of the size of the olivine particles used, centered at 138 µm. Observation and characterization of the solids showed that the residue is principally formed by unreacted olivine, whereas the fines consist mainly of carbonates (below 40 µm) with more silica in the range 40-106 µm: this segregation with particle size appears promising for separated beneficiation of the silica and the carbonates formed.