Direct dry gas-solid carbonation is a simple approach towards mineral carbon dioxide sequestration. The route theoretically implies the direct reaction of CO2 with silicates of Calcium and Magnesium in dry condition to form stable, insoluble metal carbonates. The mining regions of southern Québec have a large deposit of serpentinite residues. The current study examines the suitability of serpentinite mining residues to use as feedstock material for mineral carbonation. The focus of the present work is to assess the CO2 removal efficiency of the residue from a simulated flue gas mixture of a typical cement plant (18 Vol% CO2). This approach avoids the requirement of separate CO2 capture and preconcentration prior to mineral carbonation. The reaction parameters considered are temperature, pressure and time. The optimization of parameters is carried out for the maximum CO2 removal efficiency (%) from the feed gas. Operating condition for CO2 removal is optimized at 258 °C, 5.6 barg (pCO2 ≈ 1) for 310 minutes with a removal efficiency of 37%. Preliminary analysis of reacted solid indicates carbonation is null at optimum condition, possibly a reversible adsorption might be responsible for the depletion of CO2 from feed gas. The study also checks the importance of pre-treatment options such as grinding, magnetic separation and heat treatment on CO2 removal. A separate optimization study is carried out for magnetic separation of serpentinite residue and the separation parameters are optimized at an initial pulp density of 40% and magnetic intensity of 7.5*10-3 T with about 70% of iron oxide removal from the initial feed.
Mineral carbonation of serpentinite mining residue offers an environmentally secure and permanent storage of carbon dioxide. The strategy of using readily available mining residue for the direct treatment of flue gas could improve the energy demand and economics of CO2 sequestration by avoiding the mineral extraction and separate CO2 capture steps. The present is a laboratory scale study to assess the possibility of CO2 fixation in serpentinite mining residues via direct gas-solid reaction. The degree of carbonation is measured both in the absence and presence of water vapor in a batch reactor. The gas used is a simulated gas mixture reproducing an average cement flue gas CO2 composition of 18 vol.% CO2. The reaction parameters considered are temperature, total gas pressure, time, and concentration of water vapor. In the absence of water vapor, the gas-solid carbonation of serpentinite mining residues is negligible, but the residues removed CO2 from the feed gas possibly due to reversible adsorption. The presence of small amount of water vapor enhances the gas-solid carbonation, but the measured rates are too low for practical application. The maximum CO2 fixation obtained is 0.07 g CO2 when reacting 1 g of residue at 200 °C and 25 barg (pCO2 ≈ 4.7) in a gas mixture containing 18 vol.% CO2 and 10 vol.% water vapor in 1 h. The fixation is likely surface limited and restricted due to poor gas-solid interaction. It was identified that both the relative humidity and carbon dioxide-water vapor ratio have a role in CO2 fixation regardless of the percentage of water vapor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.