1608 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Scanning Electron Microscopy with Energy Dispersive
X-ray Spectroscopy (SEM/EDX)
SEM/EDX was used to follow changes occurring at the
surface of all four samples during the leaching period.
Different regions were followed in each sample, including
regions with and without chalcopyrite grains. A Hitachi
TM4000Plus was used to obtain backscattered electron
(BSE) images, coupled with elemental maps produced
by an AZtec EDX system from Oxford Instruments. The
accelerating voltage used for the acquisition of the BSE
images was 20 kV.
X-ray Photoelectron Spectroscopy (XPS)
XPS was used to study the surface of two samples (remov-
able samples B and D in Figure 1), which were analysed
at different points throughout the leaching period. Specific
regions (400 µm in diameter) that initially contained chal-
copyrite grains at the surface were targeted with XPS dur-
ing all the measurements. A Thermo Scientific K-Alpha
X-ray Photoelectron Spectrometer was used for the anal-
ysis, considering a base pressure of ~8×10–11 bar in the
analysis chamber. Survey spectra were collected using an
energy step size of 1 eV, a pass energy of 100 eV, and a
dwell time of 25 ms. High resolution spectra of regions cor-
responding to carbon (C1s), oxygen (O1s), sulphur (S2p),
iron (Fe2p), copper (Cu2p), and calcium (Ca2p) were also
collected, using an energy step size of 0.1 eV, a pass energy
of 20 eV, and a dwell time of 50 ms. The collected spectra
were calibrated using the C1s peak corresponding to adven-
titious carbon, which was set to 284.6 eV.
RESULTS
This section will provide a summary of part of the data
obtained through the application of the methodology.
Emphasis is placed in using these results to demonstrate
how these data can expand the spatiotemporal understand-
ing of the column leaching process.
Solution Assay Results
Data from conventional hydrometallurgical assays to mea-
sure properties of solutions collected at intermediate points
within the column leaching system have allowed observing
how changes in the solution occur in the axial direction.
Figure 3 shows how the concentration of copper changes
over time in the solution collected at the outlet of each of
the columns. The measured copper concentration of the
feed solution (0.53 g/L) is included for comparison. Copper
concentration is reported instead of copper extraction to
help visualise the cases in which the solution lost copper.
The solution is expected to become enriched in copper
as it goes through each column, and this trend is observed
throughout most of the leaching period. However, while
some copper was extracted from the first column during
the first leaching day, the copper concentrations in the
outlets of the remaining columns were significantly lower
than the concentration in the feed. This implies that cop-
per was precipitating in the last two columns. This can be
Figure 2. Reconstruction of one of the columns before leaching: (a) 3D rendering of the
column and (b) a 2D slice (cross-section) of the column. Grains highlighted in yellow
correspond to sulphide-containing minerals while the rock matrix is shown in grey
Scanning Electron Microscopy with Energy Dispersive
X-ray Spectroscopy (SEM/EDX)
SEM/EDX was used to follow changes occurring at the
surface of all four samples during the leaching period.
Different regions were followed in each sample, including
regions with and without chalcopyrite grains. A Hitachi
TM4000Plus was used to obtain backscattered electron
(BSE) images, coupled with elemental maps produced
by an AZtec EDX system from Oxford Instruments. The
accelerating voltage used for the acquisition of the BSE
images was 20 kV.
X-ray Photoelectron Spectroscopy (XPS)
XPS was used to study the surface of two samples (remov-
able samples B and D in Figure 1), which were analysed
at different points throughout the leaching period. Specific
regions (400 µm in diameter) that initially contained chal-
copyrite grains at the surface were targeted with XPS dur-
ing all the measurements. A Thermo Scientific K-Alpha
X-ray Photoelectron Spectrometer was used for the anal-
ysis, considering a base pressure of ~8×10–11 bar in the
analysis chamber. Survey spectra were collected using an
energy step size of 1 eV, a pass energy of 100 eV, and a
dwell time of 25 ms. High resolution spectra of regions cor-
responding to carbon (C1s), oxygen (O1s), sulphur (S2p),
iron (Fe2p), copper (Cu2p), and calcium (Ca2p) were also
collected, using an energy step size of 0.1 eV, a pass energy
of 20 eV, and a dwell time of 50 ms. The collected spectra
were calibrated using the C1s peak corresponding to adven-
titious carbon, which was set to 284.6 eV.
RESULTS
This section will provide a summary of part of the data
obtained through the application of the methodology.
Emphasis is placed in using these results to demonstrate
how these data can expand the spatiotemporal understand-
ing of the column leaching process.
Solution Assay Results
Data from conventional hydrometallurgical assays to mea-
sure properties of solutions collected at intermediate points
within the column leaching system have allowed observing
how changes in the solution occur in the axial direction.
Figure 3 shows how the concentration of copper changes
over time in the solution collected at the outlet of each of
the columns. The measured copper concentration of the
feed solution (0.53 g/L) is included for comparison. Copper
concentration is reported instead of copper extraction to
help visualise the cases in which the solution lost copper.
The solution is expected to become enriched in copper
as it goes through each column, and this trend is observed
throughout most of the leaching period. However, while
some copper was extracted from the first column during
the first leaching day, the copper concentrations in the
outlets of the remaining columns were significantly lower
than the concentration in the feed. This implies that cop-
per was precipitating in the last two columns. This can be
Figure 2. Reconstruction of one of the columns before leaching: (a) 3D rendering of the
column and (b) a 2D slice (cross-section) of the column. Grains highlighted in yellow
correspond to sulphide-containing minerals while the rock matrix is shown in grey