1610 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
have been identified: (1) copper in solution and sulphide
dissolution will not provide equivalent results as not all sul-
phides will contain copper, and (2) the assessment based
on micro-CT is currently only tracking changes in bright
phases within the image, although some of these may not
be sulphides.
These two issues can be addressed through more exten-
sive processing of the micro-CT data. This would involve
tracking copper-containing grains over time based on a
more thorough 3D mineral identification. To achieve this,
the micro-CT images require calibration by providing accu-
rate 2D mineral maps of certain slices produced by SEM/
EDX analysis coupled with mineral mapping software (e.g.,
MLA or QEMSCAN) (Reyes et al., 2017 Salinas-Farran et
al., 2022). Incorporating this procedure to the methodol-
ogy will be conducted in future work.
Despite the differences between the conventional solu-
tion assay results and those obtained using micro-CT, it is
important to recognise that micro-CT can provide infor-
mation that is not produced by solution assays. Solution
assays only provide total copper extraction information,
without any indication of the origin of this copper within
the column. The use of micro-CT could estimate the extent
of leaching while also determining which grains are being
leached, as well as their degree of liberation and their loca-
tion within a particle or within the column, information
that could be used for troubleshooting purposes.
Structural Assessment
In addition to assessing the progress of leaching, micro-CT
can be used to assess structural features or processes such
as the formation of cracks in the particles without disrupt-
ing the leaching process. This assessment can be useful as
the formation or expansion of cracks can allow the leaching
solution to reach locations that were previously inaccessi-
ble. Micro-CT can provide information about the location
and the size of any new or existing cracks, including both
connected and non-connected cracks or pores.
While the technique captures volumetric information,
this paper will prove the usefulness of the methodology by
focusing on three slices corresponding to the same cross-
section (extracted from the first column). Figure 6 shows
these slices, which correspond to images obtained before
leaching began (day 0), as well as after 22 days and 72 days
of leaching. As shown in Figure 6, the image corresponding
to day 0 shows a very limited crack network (considering
the resolution limitations of the image based on the voxel
size). Numerous cracks were formed during the first 22 days
of leaching, although the formation of these cracks appears
to occur preferentially on certain particles. The remain-
ing days of leaching do not result in significant changes in
the crack network of the particles: while some cracks are
formed or expand during the latter period of leaching, these
changes are not as substantial as those observed during the
first 22 days. Thus, the use of micro-CT seems to suggest
that the structural changes that are detectable within the
0.5
1
1.5
2
2.5
3
3.5
4
0 20 40 60 80
Time (days)
Column 1 output
Column 2 output
Column 3 output
Feed (pH=0.99)
Figure 4. Spatiotemporal changes in pH throughout the leaching period
pH
have been identified: (1) copper in solution and sulphide
dissolution will not provide equivalent results as not all sul-
phides will contain copper, and (2) the assessment based
on micro-CT is currently only tracking changes in bright
phases within the image, although some of these may not
be sulphides.
These two issues can be addressed through more exten-
sive processing of the micro-CT data. This would involve
tracking copper-containing grains over time based on a
more thorough 3D mineral identification. To achieve this,
the micro-CT images require calibration by providing accu-
rate 2D mineral maps of certain slices produced by SEM/
EDX analysis coupled with mineral mapping software (e.g.,
MLA or QEMSCAN) (Reyes et al., 2017 Salinas-Farran et
al., 2022). Incorporating this procedure to the methodol-
ogy will be conducted in future work.
Despite the differences between the conventional solu-
tion assay results and those obtained using micro-CT, it is
important to recognise that micro-CT can provide infor-
mation that is not produced by solution assays. Solution
assays only provide total copper extraction information,
without any indication of the origin of this copper within
the column. The use of micro-CT could estimate the extent
of leaching while also determining which grains are being
leached, as well as their degree of liberation and their loca-
tion within a particle or within the column, information
that could be used for troubleshooting purposes.
Structural Assessment
In addition to assessing the progress of leaching, micro-CT
can be used to assess structural features or processes such
as the formation of cracks in the particles without disrupt-
ing the leaching process. This assessment can be useful as
the formation or expansion of cracks can allow the leaching
solution to reach locations that were previously inaccessi-
ble. Micro-CT can provide information about the location
and the size of any new or existing cracks, including both
connected and non-connected cracks or pores.
While the technique captures volumetric information,
this paper will prove the usefulness of the methodology by
focusing on three slices corresponding to the same cross-
section (extracted from the first column). Figure 6 shows
these slices, which correspond to images obtained before
leaching began (day 0), as well as after 22 days and 72 days
of leaching. As shown in Figure 6, the image corresponding
to day 0 shows a very limited crack network (considering
the resolution limitations of the image based on the voxel
size). Numerous cracks were formed during the first 22 days
of leaching, although the formation of these cracks appears
to occur preferentially on certain particles. The remain-
ing days of leaching do not result in significant changes in
the crack network of the particles: while some cracks are
formed or expand during the latter period of leaching, these
changes are not as substantial as those observed during the
first 22 days. Thus, the use of micro-CT seems to suggest
that the structural changes that are detectable within the
0.5
1
1.5
2
2.5
3
3.5
4
0 20 40 60 80
Time (days)
Column 1 output
Column 2 output
Column 3 output
Feed (pH=0.99)
Figure 4. Spatiotemporal changes in pH throughout the leaching period
pH