Artículo
Reactive Transport Modeling of Natural Carbon Sequestration in Ultramafic Mine Tailings
Bea, Sergio Andrés
; Wilson, S. A.; Mayer, Klaus Ulrich; Dipple, G. M.; Power, I. M.; Gamazo, Pablo Andrés
Fecha de publicación:
05/2012
Editorial:
Soil Science Society of America
Revista:
Vadose Zone Journal
ISSN:
1539-1663
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Atmospheric CO2 is naturally sequestered in ultramafi c mine tailings as a result of the weathering of serpentine minerals [Mg3Si2O5(OH)4] and brucite [Mg(OH)2], and subsequent mineralization of CO2 in hydrated magnesium carbonate minerals, such as hydromagnesite [Mg5(CO3)4(OH)2·4H2O]. Understanding the CO2 trapping mechanisms is key to evaluating the capacity of such tailings for carbon sequestration. Natural CO2 sequestration in subaerially exposed ultramafic tailings at a mine site near Mount Keith, Australia is assessed with a process-based reactive transport model. The model formulation includes unsaturated flow, equations accounting for energy balance and vapor diffusion, fully coupled with solute transport, gas diffusion, and geochemical reactions. Atmospheric boundary conditions accounting for the effect of climate variations are also included. Kinetic dissolution of serpentine, dissolution-precipitation on of brucite and primary carbonates-calcite (CaCO3), dolomite [MgCa(CO3)2], magnesite (MgCO3), as well as the formation of hydromagnesite, halite (NaCl), gypsum (CaSO4·2H2O), blödite [Na2Mg(SO4)2·4H2O], and epsomite [MgSO4·7H2O]-are considered. Simulation on results are consistent with field observations and mineralogical data from tailings that weathered for 10 yr. Precipitation of hydromagnesite is both predicted and observed, and is mainly controlled by the dissolution on of serpentine (the source of Mg) and equilibrium with CO2 ingressing from the atmosphere. The predicted rate for CO2 entrapment in these tailings ranges between 0.6 and 1 kg m-2 yr-1. However, modeling results suggest that this rate is sensitive to CO2 ingress through the mineral waste and may be enhanced by several mechanisms, including atmospheric pumping.
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Articulos (IHLLA)
Articulos de INSTITUTO DE HIDROLOGIA DE LLANURAS "DR. EDUARDO JORGE USUNOFF"
Articulos de INSTITUTO DE HIDROLOGIA DE LLANURAS "DR. EDUARDO JORGE USUNOFF"
Citación
Bea, Sergio Andrés; Wilson, S. A.; Mayer, Klaus Ulrich; Dipple, G. M.; Power, I. M.; et al.; Reactive Transport Modeling of Natural Carbon Sequestration in Ultramafic Mine Tailings; Soil Science Society of America; Vadose Zone Journal; 11; 2; 5-2012; 1-17
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