Scripts for publication "Beyond Bulk Grade: Mineral–Flow Accessibility Controls Pore-Scale Copper Recovery"

Abstract

Beyond Bulk Grade: Mineral–Flow Accessibility at the Pore Scale This release provides the code, analysis products, and reproducibility materials supporting the manuscript: Chakrawal et al., Beyond Bulk Grade: Mineral–Flow Accessibility Controls Pore-Scale Copper Recovery. Critical-mineral recovery is commonly interpreted in terms of bulk ore grade, but reactive fluids can dissolve only minerals that are accessible through connected pore space. This study isolates the effect of pore-scale mineral–flow geometry on copper recovery using chrysocolla leaching by dilute sulfuric acid as a model system. Twenty-five two-dimensional pore networks were constructed with nearly identical porosity, chrysocolla loading, and kinetic surface area while systematically varying the spatial relationship between chrysocolla and inlet-connected pore space. Reactive-transport simulations were performed across two experimental designs, comprising 300 simulations in total: a factorial campaign varying pressure gradient and intrinsic dissolution rate (225 simulations), and a matched-flow campaign in which all networks received approximately the same flushed pore volume over 48 hours (75 simulations). Despite nearly identical bulk copper inventories, simulated solid-phase copper recovery varied from approximately 9–21% among pore networks. Recovery depended on the interaction between dissolution kinetics and the amount of acid-bearing fluid contacting initially accessible chrysocolla. Even after controlling for total leach volume, recovery decreased as mineral distance from connected pore space increased. Péclet–Damköhler analysis identified the governing transport–reaction regimes but did not, by itself, explain differences in recovery among geometries. Two pre-reaction metrics quantify this geometric control: Accessible chrysocolla fraction (f_Cu,acc): fraction of chrysocolla located within one voxel of inlet-connected pore space. Reactive accessibility length (l_r): median Euclidean distance from chrysocolla voxels to inlet-connected pore space. Together, the simulations demonstrate that bulk grade alone is insufficient to characterize reactive accessibility at the pore scale and that simple image-derived mineral–flow accessibility metrics can provide additional information relevant to leaching behavior. Contents of this release The archived repository contains the manuscript code snapshot, including: Python code for geometry construction, analysis, and manuscript figures; pore-network screening and analysis tables; figure products used in the manuscript and Supporting Information; Darcy–Stokes comparison and permeability-analysis tools; flow solvers used for Supporting Information analyses; aqueous speciation databases used by the PFLOTRAN reactive-transport simulations; and scripts and documentation for reproducing manuscript figures from the archived analysis products. Software requirements Python 3 with NumPy, pandas, Matplotlib, and h5py is sufficient for reproducing the archived analysis and figures. PFLOTRAN is required to regenerate the reactive-transport simulations. Acknowledgments This work was supported by EMSL AI-Enabled Pore-Scale Modeling for Critical Mineral and Metal Applications, part of EMSL’s Bridging Soil Scales science campaign. The Environmental Molecular Sciences Laboratory (EMSL) is a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program under Contract No. DE-AC05-76RL01830. Pacific Northwest National Laboratory, Richland, Washington, USA. ## DISCLAIMER This material was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the United States Department of Energy, nor Battelle, nor any of their employees, nor any jurisdiction or organization that has cooperated in the development of these materials, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness or any information, apparatus, product, software, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC05-76RL01830