CO₂ fixation using magnesium silicate minerals. Part 2: Energy efficiency and integration with iron-and steelmaking

Mineral carbonation presents itself as the most promising method to sequester CO₂ in Finland. A staged process for CO₂ mineralisation, using magnesium silicates, is being intensively developed at åbo Akademi. A process energy analysis is made based on the most energy intensive steps, i.e. the heat treatment of the magnesium silicate rock and the carbonation reaction. Aspen Plus^® software was used to model the process and pinch and exergy analyses were performed to acquire information on process layout for optimal heat recovery and integration. The simulations allow for concluding that the fixation of 1 kg of CO₂ requires 3.04 MJ and 3.1 kg of serpentinite mineral rock. Additionally, the process gives considerable amounts of FeOOH and Ca(OH)₂ as by-products making the integration of mineral carbonation with the steelmaking industry a very attractive opportunity to reduce CO₂ emissions and raw materials inputs.