1605
Multimodal Approach to Obtain Spatiotemporal Insights into
Column Leaching Experiments Through Surface-Level Analysis
and 3D Imaging
Gonzalo Larrabure, Stephen J. Neethling, Luis Salinas-Farran, Pablo R. Brito-Parada
Advanced Mineral Processing Research Group, Department of Earth Science and Engineering, Imperial College London
ABSTRACT: Leaching is a complex process with important phenomena occurring at different scales. These
phenomena are often studied independently but a multimodal approach capable of accessing information
about the spatiotemporal heterogeneity of column leaching would allow a more thorough understanding of the
process. In this work we propose a methodology for assessing column leaching behaviour at ore particle, mineral
grain, and mineral surface scales in a single experimental system. This methodology combines inputs from
hydrometallurgical assays, surface-sensitive techniques (X-ray photoelectron spectroscopy), and 2D (SEM/
EDX) and 3D imaging (micro computed tomography) to understand surface processes and changes in the
leaching solution and in the mineralogy and microstructure of the particles. This multimodal approach can be
applied to different ores, and a chalcopyrite-containing ore is used here to showcase its capabilities.
INTRODUCTION
Heap leaching is an essential process required to extract
metals needed to drive the green energy transition. For
example, this process has been reported as responsible for
the production of 21% of global copper in 2017 (Marsden
&Botz, 2017). Heap leaching is also used for the extrac-
tion of valuable metals like gold, silver, and rare earth ele-
ments (Thenepalli et al., 2019). However, before beginning
a heap-level operation, column leaching experiments are
often run to optimise parameters leading to a more effi-
cient process (van Staden &Petersen, 2021 Winarko et
al., 2023).
Beyond optimisation, some efforts have been placed
on studying the various phenomena occurring during col-
umn leaching experiments to understand the process more
thoroughly. Typically, these studies aim to assess a specific
aspect of the column leaching process, such as its kinetics
(Nosrati et al., 2014 Phyo et al., 2020), hydrodynamics
(Ghasemzadeh et al., 2018 Ilankoon &Neethling, 2013),
mineralogical features (Calderón-Rodarte et al., 2017
Reyes et al., 2017 Salinas-Farran et al., 2022), surface-level
processes (Larrabure et al., 2023 Nikkhou et al., 2019), or
structural characteristics (Ai et al., 2022 Yu &Gao, 2020).
Additionally, column leaching experiments are often stud-
ied as black boxes, since the spatiotemporal heterogeneity
associated with column leaching is rarely captured. This is
due to how these experiments are operated: solution prop-
erties are typically measured only before and after passing
through the column, while solids are studied only before
and after the experiment is run. Integral approaches to
assess the spatiotemporal heterogeneity associated with col-
umn leaching have not been identified in the literature.
This paper introduces a multimodal methodology
designed to open the spatiotemporal black box character-
istic of column leaching experiments, while also exploring
phenomena occurring at surface, grain, particle, and packed
Multimodal Approach to Obtain Spatiotemporal Insights into
Column Leaching Experiments Through Surface-Level Analysis
and 3D Imaging
Gonzalo Larrabure, Stephen J. Neethling, Luis Salinas-Farran, Pablo R. Brito-Parada
Advanced Mineral Processing Research Group, Department of Earth Science and Engineering, Imperial College London
ABSTRACT: Leaching is a complex process with important phenomena occurring at different scales. These
phenomena are often studied independently but a multimodal approach capable of accessing information
about the spatiotemporal heterogeneity of column leaching would allow a more thorough understanding of the
process. In this work we propose a methodology for assessing column leaching behaviour at ore particle, mineral
grain, and mineral surface scales in a single experimental system. This methodology combines inputs from
hydrometallurgical assays, surface-sensitive techniques (X-ray photoelectron spectroscopy), and 2D (SEM/
EDX) and 3D imaging (micro computed tomography) to understand surface processes and changes in the
leaching solution and in the mineralogy and microstructure of the particles. This multimodal approach can be
applied to different ores, and a chalcopyrite-containing ore is used here to showcase its capabilities.
INTRODUCTION
Heap leaching is an essential process required to extract
metals needed to drive the green energy transition. For
example, this process has been reported as responsible for
the production of 21% of global copper in 2017 (Marsden
&Botz, 2017). Heap leaching is also used for the extrac-
tion of valuable metals like gold, silver, and rare earth ele-
ments (Thenepalli et al., 2019). However, before beginning
a heap-level operation, column leaching experiments are
often run to optimise parameters leading to a more effi-
cient process (van Staden &Petersen, 2021 Winarko et
al., 2023).
Beyond optimisation, some efforts have been placed
on studying the various phenomena occurring during col-
umn leaching experiments to understand the process more
thoroughly. Typically, these studies aim to assess a specific
aspect of the column leaching process, such as its kinetics
(Nosrati et al., 2014 Phyo et al., 2020), hydrodynamics
(Ghasemzadeh et al., 2018 Ilankoon &Neethling, 2013),
mineralogical features (Calderón-Rodarte et al., 2017
Reyes et al., 2017 Salinas-Farran et al., 2022), surface-level
processes (Larrabure et al., 2023 Nikkhou et al., 2019), or
structural characteristics (Ai et al., 2022 Yu &Gao, 2020).
Additionally, column leaching experiments are often stud-
ied as black boxes, since the spatiotemporal heterogeneity
associated with column leaching is rarely captured. This is
due to how these experiments are operated: solution prop-
erties are typically measured only before and after passing
through the column, while solids are studied only before
and after the experiment is run. Integral approaches to
assess the spatiotemporal heterogeneity associated with col-
umn leaching have not been identified in the literature.
This paper introduces a multimodal methodology
designed to open the spatiotemporal black box character-
istic of column leaching experiments, while also exploring
phenomena occurring at surface, grain, particle, and packed