InterPore2025

Natural convection facilitates deep mineral leaching and precipitation in a dead-end pore

21 May 2025, 12:50

15m

Oral Presentation (MS25) Advances in Carbon Mineralization: Unveiling Multiscale Geo-processes and Coupled Mechanisms MS25

Speaker

Jinil Park (Hanyang University)

Description

Mineral dissolution and precipitation significantly impact many geofluid systems, such as carbon mineralization and in-situ leaching. Despite its widespread observation across various fields, the mechanism to facilitate these reactions has not been proposed yet. In this study, we demonstrated that the natural convection can facilitate mineral dissolution and corresponding precipitation in a dead-end pore for the first time. To investigate this phenomenon, we designed a microfluidic chip featuring a dead-end pore adjacent to a large reservoir, enabling real-time visualization of mineral dissolution, precipitation, and fluid flow. By placing a NaCl crystal in the dead-end pore and AgNO₃ solution in the reservoir, we triggered a reaction where NaCl dissolves, chloride ions react with silver ions, and AgCl precipitates as an insoluble salt. When the pore is positioned at the bottom of the reservoir (aligned with gravity), the reaction ceases rapidly as the precipitate blocks the NaCl crystal. However, when the pore is located at the top, a density gradient forms as NaCl dissolves, inducing natural convection. This convection clears the precipitate, sustaining dissolution and precipitation over time. When the pore is positioned laterally, we observe more complex dynamics: natural convection moves precipitates downward and facilitate dissolution at the upper part, leading to asymmetrical dissolution of the NaCl crystal. Simultaneously, precipitates accumulate from the bottom at the entrance of the dead-end, confining natural convection along the crystal surface. This confinement promotes precipitate growth while establishing a mixing boundary between the dissolved NaCl and the reservoir. A parametric study varying the angle relating the salt dissolution direction to the gravity and AgNO₃ concentrations confirms that the depth and rate of mineral dissolution are proportional to the strength of natural convection. These findings enhance our understanding of gravity-driven mineral dissolution and precipitation dynamics, offering insights with broad implications for scientific and engineering applications requiring deep mineral reactions.