Conference article

The long-term storage of CO₂ using mineral sequestration is becoming increasingly interesting in many regions; especially where CO₂ underground sequestration is considered impossible or unfeasible. Despite the recognised and documented advantages of CO₂ mineral sequestration; twenty years of R&D work did not yet result in mature; economically viable technology that can be applied on a large scale. Lacking other CCS options while having access to large resources of suitable rock material; a route for carbonation of magnesium silicate mineral is currently being optimised in Finland. It involves the production of magnesium hydroxide; Mg(OH)₂ from the mineral followed by carbonation of this in a pressurised fluidised bed reactor. Although the Mg(OH)₂ production requires energy the consequent carbonation step is exothermic and the overall process could still be rendered energy neutral. Significant amounts of iron oxides are obtained as by-products. Carbonation levels of ~50% of several 100 µm diameter Mg(OH)₂ particles were obtained within 10 minutes at pressures > 20 bar and temperatures up to 500ºC. This paper reports on the latest developments of the work; addressing also process energy efficiency. Also; the large-scale application of this in Finland and at the locations of project partners abroad is briefly addressed.

Carbon dioxide sequestration; Mineral carbonation