Dynamics of Mineral Precipitation Reaction Fronts In Porous Media
EMSL Project ID
44714
Abstract
Two projects at INL will be significantly enhanced through access to EMSL facilities. Idaho National Laboratory (INL) Scientific Focus Area (SFA), sponsored by DOE's Subsurface Biogeochemistry Research Program, is titled "Understanding and Controlling Precipitation Reaction Fronts in Subsurface Environments" and focuses on how reactants mix in subsurface environments to form mineral precipitates. Fundamental presumptions of the INL SFA are that: 1) Trace metal contaminant mobility in the subsurface can be reduced by chemically or biologically stimulating precipitation of mineral phases that incorporate contaminants or that modify flow paths, and 2) the spatial and temporal distributions of mineral precipitates that are stimulated by the injection of reactants depend on the strategies to create mixing/precipitation reaction fronts. INL also collaborates with PNNL on a SciDAC project that explores multi-scale modeling of subsurface processes. Formation of mineral phases via multi-component reactions in subsurface environments involves coupling between reactant transport, reactant mixing and precipitation kinetics. The INL SFA approach is to conduct experiments at intermediate scales in order to address knowledge gaps related to meso-scale mixing interfaces in porous media, the effects of coupling between reactant mixing and mineral precipitation on reaction zone properties and behavior, and linking molecular and pore-scale processes to behavior observed at larger scales. Five experimental campaigns are planned for the SFA, each of which represents a different type of solution-solution mixing boundary. The two campaigns that this proposed EMSL Science Team project will support are: 1) mineral precipitation at the interface between solutions flowing in parallel; and 2) mineral precipitation in longitudinal mixing interfaces between sequentially injected solutions.
Access to EMSL facilities and expertise will significantly enhance the productivity of the INL SFA. Specifically, collaboration with EMSL will enable:
- Detailed analysis of the propagation of mineral precipitation fronts. This includes pore-scale characterization of the evolution of the composition, morphology and spatial distribution of mineral phases, and observations of the dynamic behavior of precipitation reaction zones caused by coupling between reactant transport and changes in permeability/porosity.
- Advancement of the simulation of the dynamics of precipitation reaction zones in porous media, using a massively parallel, fully coupled, fully-implicit reactive transport model developed at INL.
The results of this research will provide critical support for linking process models at the molecular, pore and continuum scales in environmental media. These research topics are particularly challenging in engineered systems because of the rapid kinetics driven by potentially high saturation states and consequent multiplicity of nucleation and growth mechanisms that will occur within the chemical gradients formed within the mixing zones. The multi-scale aspects of the INL SFA research program will also fit the mission, facilities and expertise at EMSL.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2011-10-01
End Date
2012-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members