XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3079
mixed using the splitter. There were 10 rounds of mixing
and splitting to get representative samples.
All representative samples were transferred to buckets
and covered with pit water (pH 1.8). Then they were sealed
for 1, 2, 3, 4, and 5 months. The first bucket was open after
a month, 2nd after 2 months, 3rd after 3 months, 4th after
4 months, and 5th after 5 months. Acidic pit water with
high iron ion content impacted the ore as even its color
changed toward yellowish, and reddish (Figure 3)
Sample preparation after each month was completed
involved decanting the water, filtering, drying, crushing
to approximately 2000 microns, splitting samples using
a rotary splitter, grinding, and flotation tests. Grinding
tests were done in a rod mill, and dry lime and water were
added to achieve 10.6 pH in grinding. A minimum of three
samples were subjected to grinding tests to determine the
grinding time needed to obtain 25% of +150 microns of
materials. Lime was varied to determine the required dose
to meet the target pH Additional samples were used for flo-
tation tests. The samples were collected after grinding tests,
with water added to achieve 25% solids and additional lime
added to achieve pH 11in flotation tests.
RESULTS AND DISCUSSIONS
Crushing and Grinding
After filtering, and drying the materials, they were crushed
and sieved to achieve –2000 microns. Then samples were
split using a rotary splitter for the next steps, including
grinding and flotation tests. Grinding tests were done in a
rod mill. The solid %was 60% during grinding. Dry lime
was added in various dosages in the rod mill to determine
the required dosage of lime to meet the target pH in the
flotation tests. In addition, a minimum of three samples
were subjected to grinding tests to determine the optimal
grinding time to obtain 25% of +150 microns for flotation
tests (Figure 4 and Table 1). The average grinding time to
achieve target particle size distribution in the rod mill for
different sets of tests was between 13.4 and 17.3 minutes.
As already mentioned, during grinding tests, various
dosages of lime were added to the rod mill to find out the
needed lime dosage to achieve pH 11 in the flotation tests.
The results are shown in Figure 5. The control ore that did
not have contact with pit water needed 2.8 kg/t lime to
reach pH 11. By exposing Estrella ore to the pit water for
a month, the dosage of lime increased to 8.2 kg/t, which
is a significant jump in lime consumption. Almost the
lime consumption was tripled. Lime consumption mod-
estly increased by increasing the month of exposure to the
Estrella pit water. It was increased from the 1st month to
the 5th from 8.2 kg/t to 11.8 kg/t. The main reason behind
the increasing lime consumption by increasing the timeline
of exposure to the pit water is because of its properties. Pit
water is acidic with a pH 1.8. Also, it contains a wide vari-
ety of ions.
Ore Characterization Studies
Representative samples were prepared to analyze elements
and mineral content for control, and all ores belong to all
5 months. Chemical and mineralogical analyses were per-
formed by X-ray fluorescence (XRF) spectrometry and
X-ray diffraction (XRD) for all samples. XRF and XRD
results are given in Table 2 and Figure 6. The copper
Figure 3. Estrella Ore before and after contacting with Estrella pit water
mixed using the splitter. There were 10 rounds of mixing
and splitting to get representative samples.
All representative samples were transferred to buckets
and covered with pit water (pH 1.8). Then they were sealed
for 1, 2, 3, 4, and 5 months. The first bucket was open after
a month, 2nd after 2 months, 3rd after 3 months, 4th after
4 months, and 5th after 5 months. Acidic pit water with
high iron ion content impacted the ore as even its color
changed toward yellowish, and reddish (Figure 3)
Sample preparation after each month was completed
involved decanting the water, filtering, drying, crushing
to approximately 2000 microns, splitting samples using
a rotary splitter, grinding, and flotation tests. Grinding
tests were done in a rod mill, and dry lime and water were
added to achieve 10.6 pH in grinding. A minimum of three
samples were subjected to grinding tests to determine the
grinding time needed to obtain 25% of +150 microns of
materials. Lime was varied to determine the required dose
to meet the target pH Additional samples were used for flo-
tation tests. The samples were collected after grinding tests,
with water added to achieve 25% solids and additional lime
added to achieve pH 11in flotation tests.
RESULTS AND DISCUSSIONS
Crushing and Grinding
After filtering, and drying the materials, they were crushed
and sieved to achieve –2000 microns. Then samples were
split using a rotary splitter for the next steps, including
grinding and flotation tests. Grinding tests were done in a
rod mill. The solid %was 60% during grinding. Dry lime
was added in various dosages in the rod mill to determine
the required dosage of lime to meet the target pH in the
flotation tests. In addition, a minimum of three samples
were subjected to grinding tests to determine the optimal
grinding time to obtain 25% of +150 microns for flotation
tests (Figure 4 and Table 1). The average grinding time to
achieve target particle size distribution in the rod mill for
different sets of tests was between 13.4 and 17.3 minutes.
As already mentioned, during grinding tests, various
dosages of lime were added to the rod mill to find out the
needed lime dosage to achieve pH 11 in the flotation tests.
The results are shown in Figure 5. The control ore that did
not have contact with pit water needed 2.8 kg/t lime to
reach pH 11. By exposing Estrella ore to the pit water for
a month, the dosage of lime increased to 8.2 kg/t, which
is a significant jump in lime consumption. Almost the
lime consumption was tripled. Lime consumption mod-
estly increased by increasing the month of exposure to the
Estrella pit water. It was increased from the 1st month to
the 5th from 8.2 kg/t to 11.8 kg/t. The main reason behind
the increasing lime consumption by increasing the timeline
of exposure to the pit water is because of its properties. Pit
water is acidic with a pH 1.8. Also, it contains a wide vari-
ety of ions.
Ore Characterization Studies
Representative samples were prepared to analyze elements
and mineral content for control, and all ores belong to all
5 months. Chemical and mineralogical analyses were per-
formed by X-ray fluorescence (XRF) spectrometry and
X-ray diffraction (XRD) for all samples. XRF and XRD
results are given in Table 2 and Figure 6. The copper
Figure 3. Estrella Ore before and after contacting with Estrella pit water