In co-dissolution and precipitation systems, the dynamic evolution of the coating layer depends on two intertwining processes: the dissolution of the primary mineral that is needed for subsequent precipitation and the suppression of the dissolution reaction as a result of secondary mineral precipitation. The resulting thickness and texture of the precipitating layer will affect the progression of geochemical reactions, flow and transport processes at macroscopic scales. Understanding the interplay between macroscopic flow regimes and microscopic reaction mechanisms (e.g. nucleation and crystal growth pathways) in controlling the dynamic evolution of the coating layer has important implications for predicting natural weathering processes, scaling in the subsurface energy production systems, and etc. Previous experimental studies have highlighted drastically different coating behaviors as the fluid composition changes. In this study, we use continuum and pore-scale models to investigate the relative contribution of local feedback loop between reaction rate and solute transport, and the saturation dependent nucleation rate and crystal morphology. The results will provide new insights regarding the application and extension of the passivation treatment that has been typically applied in continuum scale description of system evolution with co-dissolution and precipitation.

Multi-scale investigation of the dynamic evolution of mineral coating

ACS Spring Meeting 2021

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