Reaction Path Geochemical Modeling as an Essential and Inexpensive Tool in Evaluating Mineral Carbonation-Type Carbon Capture, Utilization, and Storage Projects

Abstract

Mineral carbonation of Fe- and Mg-bearing rocks is one of the potential ways to store point-source carbon dioxide emissions. Geochemical modeling is an essential tool to help select the best mafic rock reactant and to optimize reaction conditions. This case study demonstrates the utility of reaction path geochemical modeling (EQ3/6) to evaluate carbon storage potential during ex-situ mineral carbonation of ten mafic rock samples from Nevada. Models were run using arbitrary dissolution kinetics at temperatures between 0 and 200°C. A subset of models were run using true dissolution kinetics. In the models, carbon is stored in 5 mineral phases: magnesite, siderite, dolomite, calcite, and dawsonite, with magnesite and dolomite the most abundant. The arbitrary kinetics models resulted in 4.5 to 13 moles of carbon stored per kg of reacted mafic rock. True kinetics models only resulted in 1 to 2 moles of carbon stored, but the models only reacted 12.5 to 15 weight percent of the mafic rock inputs. Product minerals using the arbitrary kinetics model have volumes 150% to 470% larger than the reactant volumes, whereas using true kinetics the models have a modest increase. Reaction path geochemical modeling is a vital and inexpensive tool to help optimize costs and reaction conditions for ex-situ mafic rock carbonation projects. These data can also be used as inputs for facility size optimization and economic forecasting.

AAPG Datapages/Search and Discovery Article #90373 © 2019 AAPG Eastern Section Meeting, Energy from the Heartland, Columbus, Ohio, October 12-16, 2019