XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1613
Although not shown in these figures, the copper region
only exhibited features associated with copper sulphides
before leaching and no copper was detected at the surface
after leaching started. The combination of these observa-
tions suggests one of the following hypotheses: (1) copper
is being leached from the surface and XPS is then detecting
grains that do not contain copper that were underneath the
original copper-containing grains, (2) iron-containing sul-
phates are being formed or depositing over the chalcopyrite
grains, which blocks the copper from being detected by the
technique. The first hypothesis can be ruled out because
SEM/EDX revealed that copper was still present in the
region studied with XPS, although not in the topmost lay-
ers of the surface: SEM/EDX can probe deeper within the
particle than XPS. Thus, combining the data produced by
XPS and SEM/EDX can reveal more information and pro-
vide a clearer picture of the surface-level processes occur-
ring during column leaching.
CONCLUDING REMARKS
This study has introduced a methodology capable of
producing information leading to a more thorough
understanding of the spatiotemporal heterogeneity that
characterises column leaching experiments. This methodol-
ogy enables going beyond the conventional scope of results
that can be obtained through solution assays by dividing a
single leaching column into three columns in series. This
allows understanding how the solution changes based on
the position within the column system and not only over
time. Likewise, non-destructive techniques (micro-CT,
SEM/EDX, and XPS) have been applied to the analysis of
the solid particles throughout the leaching period to extract
information both at a volumetric and at a surface level.
The results presented in this study aim to show that
the proposed methodology can produce more informa-
tive data than conventional column leaching experiments.
Additional work is still required to achieve the potential of
the applications of this methodology. Future work includes
(1) fully analysing the solution assay results, (2) produc-
ing a 3D mineral map to enable tracking and identifying
the mineralogy of specific grains accurately, and (3) thor-
oughly processing the XPS and SEM/EDX results of all
the samples. Further processing of these data is required to
transform it into key insights to describe column leaching
Figure 7. High resolution sulphur and iron regions of the XPS spectrum, and backscattered electron micrographs overlayed
with copper elemental maps (copper is marked in orange) of the region where the XPS was acquired (XPS focal spot is marked
in red) before leaching, as well as after 3 days and 35 days of leaching
Although not shown in these figures, the copper region
only exhibited features associated with copper sulphides
before leaching and no copper was detected at the surface
after leaching started. The combination of these observa-
tions suggests one of the following hypotheses: (1) copper
is being leached from the surface and XPS is then detecting
grains that do not contain copper that were underneath the
original copper-containing grains, (2) iron-containing sul-
phates are being formed or depositing over the chalcopyrite
grains, which blocks the copper from being detected by the
technique. The first hypothesis can be ruled out because
SEM/EDX revealed that copper was still present in the
region studied with XPS, although not in the topmost lay-
ers of the surface: SEM/EDX can probe deeper within the
particle than XPS. Thus, combining the data produced by
XPS and SEM/EDX can reveal more information and pro-
vide a clearer picture of the surface-level processes occur-
ring during column leaching.
CONCLUDING REMARKS
This study has introduced a methodology capable of
producing information leading to a more thorough
understanding of the spatiotemporal heterogeneity that
characterises column leaching experiments. This methodol-
ogy enables going beyond the conventional scope of results
that can be obtained through solution assays by dividing a
single leaching column into three columns in series. This
allows understanding how the solution changes based on
the position within the column system and not only over
time. Likewise, non-destructive techniques (micro-CT,
SEM/EDX, and XPS) have been applied to the analysis of
the solid particles throughout the leaching period to extract
information both at a volumetric and at a surface level.
The results presented in this study aim to show that
the proposed methodology can produce more informa-
tive data than conventional column leaching experiments.
Additional work is still required to achieve the potential of
the applications of this methodology. Future work includes
(1) fully analysing the solution assay results, (2) produc-
ing a 3D mineral map to enable tracking and identifying
the mineralogy of specific grains accurately, and (3) thor-
oughly processing the XPS and SEM/EDX results of all
the samples. Further processing of these data is required to
transform it into key insights to describe column leaching
Figure 7. High resolution sulphur and iron regions of the XPS spectrum, and backscattered electron micrographs overlayed
with copper elemental maps (copper is marked in orange) of the region where the XPS was acquired (XPS focal spot is marked
in red) before leaching, as well as after 3 days and 35 days of leaching