XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1609
explained by the consumption of acid due to side reactions
with gangue, which led to a sharp increase in the pH of the
solutions during the first day, as shown in Figure 4. This
figure also shows that, as the leaching progresses, the pH
of the solutions collected after each column tend to match
the pH of the feed solution. This indicates that most of
the minerals that cause a high acid consumption reacted or
were leached at an early stage of the process.
Beyond the observation regarding the precipitation of
copper during the first day, the analysis of the remaining
features presented in the collected hydrometallurgical data
are the subject of future work. However, the trends shown
in these figures demonstrate the capacity of the methodol-
ogy to provide information about how the solution changes
as it goes down the column leaching system. A conven-
tional column leaching experiment with a single column
of a height equivalent to the three columns in series would
only have provided the data corresponding to the “Column
3 outlet,” thus failing to capture the spatial heterogeneity
of the system. Additional data corresponding to the spatio-
temporal changes in the ORP and in the concentration of
total iron, ferrous ion, and ferric ion were also collected as
part of the experiment but are not shown or discussed in
this paper.
Leaching Progress Assessment
Tracking the kinetics of the process is essential in leach-
ing experiments. Conventionally, the leaching progress is
assessed using solution assays to determine how much of
the valuable metal has been extracted from the ore. This
approach was considered as part of this study, and the
results are shown in the extraction plot in Figure 5a. This
figure suggests that approximately 41.6% of the copper was
extracted from the ore according to solution assays. These
results were compared to the estimations based on micro-
CT of sulphide dissolution as a proxy for leaching progress
assessment, which are also shown in Figure 5a for each of
the three columns.
It should be noted that the two leaching progress
assessment methods are not producing the same results.
However, Figure 5b shows that the overall leaching progress
estimated by the two methods show a similar trend, even
though the absolute extraction or dissolution values do not
match. Two key reasons that explain these observations
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 5 8 14 22 35 48 67 72
Time (days)
Column 1 output Column 2 output
Column 3 output Feed (Cu: 0.53 g/L)
Figure 3. Spatiotemporal changes in copper concentration throughout the leaching
period. The error bars correspond to the standard deviation of copper concentration
solution assays performed in triplicate
Copper
concentration
(g/L)
explained by the consumption of acid due to side reactions
with gangue, which led to a sharp increase in the pH of the
solutions during the first day, as shown in Figure 4. This
figure also shows that, as the leaching progresses, the pH
of the solutions collected after each column tend to match
the pH of the feed solution. This indicates that most of
the minerals that cause a high acid consumption reacted or
were leached at an early stage of the process.
Beyond the observation regarding the precipitation of
copper during the first day, the analysis of the remaining
features presented in the collected hydrometallurgical data
are the subject of future work. However, the trends shown
in these figures demonstrate the capacity of the methodol-
ogy to provide information about how the solution changes
as it goes down the column leaching system. A conven-
tional column leaching experiment with a single column
of a height equivalent to the three columns in series would
only have provided the data corresponding to the “Column
3 outlet,” thus failing to capture the spatial heterogeneity
of the system. Additional data corresponding to the spatio-
temporal changes in the ORP and in the concentration of
total iron, ferrous ion, and ferric ion were also collected as
part of the experiment but are not shown or discussed in
this paper.
Leaching Progress Assessment
Tracking the kinetics of the process is essential in leach-
ing experiments. Conventionally, the leaching progress is
assessed using solution assays to determine how much of
the valuable metal has been extracted from the ore. This
approach was considered as part of this study, and the
results are shown in the extraction plot in Figure 5a. This
figure suggests that approximately 41.6% of the copper was
extracted from the ore according to solution assays. These
results were compared to the estimations based on micro-
CT of sulphide dissolution as a proxy for leaching progress
assessment, which are also shown in Figure 5a for each of
the three columns.
It should be noted that the two leaching progress
assessment methods are not producing the same results.
However, Figure 5b shows that the overall leaching progress
estimated by the two methods show a similar trend, even
though the absolute extraction or dissolution values do not
match. Two key reasons that explain these observations
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 5 8 14 22 35 48 67 72
Time (days)
Column 1 output Column 2 output
Column 3 output Feed (Cu: 0.53 g/L)
Figure 3. Spatiotemporal changes in copper concentration throughout the leaching
period. The error bars correspond to the standard deviation of copper concentration
solution assays performed in triplicate
Copper
concentration
(g/L)