XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 779
After the preliminary study that analyzed the effect
of water quality on metallurgical performance of different
minerals, tests to estimate the future process water were
carried out, considering future minerals for the period
2024–2028.
Experimental Procedure to Estimate the Future
Process Water
The experimental procedure was based on the test protocol
for estimating water changes in mineral processing plants
operating with closed water circulation (Le et al., 2020b).
The protocol was adapted to the future changes in the water
quality at the Collahuasi concentrator, due to the projected
environmental constraints, and the changes in the mineral
characteristics for the next five years (2024 – 2028).
To simulate the evolution of the process water quality,
due to the partial change from continental water (CW) to
remineralized desalinated water (RDW), a series of disso-
lution-dilution cycle tests (DDCT) were performed. These
tests consisted of evaluating the dissolution of minerals spe-
cies in the process water during the mineral flotation, and
the use of the flotation tailings water as recovered water,
combined with the freshwater makeup for a new flotation
cycle, until the process water reaches an equilibrium. For
each DDCT, the freshwater makeup and the water quality
resulting of each flotation cycle was analysed (total of 11
points), considering conductivity, pH, ORP. In addition,
for the uneven cycles (1, 3, 5, 7, 9 y 11) the ions: Ca++, K+,
Na+, Cl–, SO4=, NO3–, Cu++, Fe++, Mo++ and Mg++ were
analysed.
The dissolution/dilution cycle tests (DDCT) were
developed in a flotation cell of 2700 mL, like that used
for standard flotation tests (Table 1). The cell walls were
adapted to operate without froth discharge, facilitating the
mineral dissolution. Figure 3 shows the procedure of the
Dissolution/Dilution Cycling Test (DDCT).
Four minerals were used for the DDCT, represent-
ing each year of the future planning (from 2024 to 2028).
The initial water was process water for the first year, and a
mixture of continental water (CW) and desalinated water
(RDW), in a proportion of 50–50%, for the next three
years. On the other hand, the makeup water used in the
tests was the mixture for the first three years and a new
Table 2. Characteristics of minerals evaluated in the batch tests
Mineral FA Mineral FB Mineral SA Mineral SB Mineral FS
Feed Cu grade, %1.27 0.95 0.96 0.84 1.14
Main Cu sulfide
relative content
Chalcopyrite (68%) Chalcopyrite (71%) Chalcocite (49%) Chalcocite (66%) Chalcopyrite (60%)
Pyrite content, %0.6 1.5 11.9 14.6 4.5
Clays content, %0.6 0.4 16.7 10.1 4.2
P
80 ,µm 210 210 210 210 210
Feed solid content, %30 30 30 30 30
Table 3. Characteristics of water quality evaluated in the batch tests
Water Type Desalinated Tap water Mix 1 Mix 2 Process Seawater
Conductivity, µS/cm 494 1,555 10,306 32,384 22,519 49,555
pH 8.3 7.2 8.2 8.0 8.5 7.9
Total dissolved solids, mg/L 310 890 7,515 23,726 17,620 36,335
Figure 2. Flotation cell used for batch tests
After the preliminary study that analyzed the effect
of water quality on metallurgical performance of different
minerals, tests to estimate the future process water were
carried out, considering future minerals for the period
2024–2028.
Experimental Procedure to Estimate the Future
Process Water
The experimental procedure was based on the test protocol
for estimating water changes in mineral processing plants
operating with closed water circulation (Le et al., 2020b).
The protocol was adapted to the future changes in the water
quality at the Collahuasi concentrator, due to the projected
environmental constraints, and the changes in the mineral
characteristics for the next five years (2024 – 2028).
To simulate the evolution of the process water quality,
due to the partial change from continental water (CW) to
remineralized desalinated water (RDW), a series of disso-
lution-dilution cycle tests (DDCT) were performed. These
tests consisted of evaluating the dissolution of minerals spe-
cies in the process water during the mineral flotation, and
the use of the flotation tailings water as recovered water,
combined with the freshwater makeup for a new flotation
cycle, until the process water reaches an equilibrium. For
each DDCT, the freshwater makeup and the water quality
resulting of each flotation cycle was analysed (total of 11
points), considering conductivity, pH, ORP. In addition,
for the uneven cycles (1, 3, 5, 7, 9 y 11) the ions: Ca++, K+,
Na+, Cl–, SO4=, NO3–, Cu++, Fe++, Mo++ and Mg++ were
analysed.
The dissolution/dilution cycle tests (DDCT) were
developed in a flotation cell of 2700 mL, like that used
for standard flotation tests (Table 1). The cell walls were
adapted to operate without froth discharge, facilitating the
mineral dissolution. Figure 3 shows the procedure of the
Dissolution/Dilution Cycling Test (DDCT).
Four minerals were used for the DDCT, represent-
ing each year of the future planning (from 2024 to 2028).
The initial water was process water for the first year, and a
mixture of continental water (CW) and desalinated water
(RDW), in a proportion of 50–50%, for the next three
years. On the other hand, the makeup water used in the
tests was the mixture for the first three years and a new
Table 2. Characteristics of minerals evaluated in the batch tests
Mineral FA Mineral FB Mineral SA Mineral SB Mineral FS
Feed Cu grade, %1.27 0.95 0.96 0.84 1.14
Main Cu sulfide
relative content
Chalcopyrite (68%) Chalcopyrite (71%) Chalcocite (49%) Chalcocite (66%) Chalcopyrite (60%)
Pyrite content, %0.6 1.5 11.9 14.6 4.5
Clays content, %0.6 0.4 16.7 10.1 4.2
P
80 ,µm 210 210 210 210 210
Feed solid content, %30 30 30 30 30
Table 3. Characteristics of water quality evaluated in the batch tests
Water Type Desalinated Tap water Mix 1 Mix 2 Process Seawater
Conductivity, µS/cm 494 1,555 10,306 32,384 22,519 49,555
pH 8.3 7.2 8.2 8.0 8.5 7.9
Total dissolved solids, mg/L 310 890 7,515 23,726 17,620 36,335
Figure 2. Flotation cell used for batch tests