XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 641
It was demonstrated that depending on the quality of
the water to be treated, pH and lime addition from reac-
tor A1 to reactors B2 and B3 can be modified as part of a
continuous optimization of the process.
The optimal reaction times for each reactor was 30
minutes. The best sludge recirculation ratio (SRR) obtained
was 10:1. The sedimentation rates obtained from the mod-
ified Talmadge-Fitch Kynch tests were in the ranges of
((3.2–7.6 ft2 /(tone/day)). Sulfates in the discharge of the
thickener had concentrations of 2,000 mg/L.
When there is high sodium in the feed solution
(100 mg/L), the sodium cation reduces the precipitation
efficiency of sulfates as calcium sulfates, and increases the
optimum precipitation point from 2,000 mg/L to values
above 3,000 mg/L.
Results of the Sand Filter Process
The reverse osmosis permeate generated required additional
treatment, mainly to reduce arsenic.
Green sand was selected as the filter medium for this
purpose and was found to be effective. Washing with caus-
tic soda was sufficient and effective to sustain constant
operation of the green sands filter media.
Results of Biological Activity Analyses
The 17 different feed sources that fed the pilot plant were
analyzed as well as internal samples from the water treat-
ment process. A large variability of biological activity was
observed in these sources. The presence of biomasses were
not observed in the UF filtrate, which aligns with the
membranes filtration spectrum (Figures 25 and 26). The
discovery of biological masses in the feed water of the pilot
plant confirmed that the UF membranes had been fouled
by biological masses, because the UF is the first solid-liq-
uid separation step in the pilot plant process. This finding
requires two controls, first is source control of the biologi-
cal growth in the feed water and the second is an effective
cleaning procedure to remove biological masses from the
membranes. Figure 24 shows the biological activity of two
feed sources and the feed to the HDS process. The type 1
feed comes from a revegetated area, which is the source of
the highest concentrations of bio mass’s observed.
Produced Water Quality Results
Lab results demonstrated that it is possible to meet the tar-
get water quality parameters. In the following figures the
main parameters that were the objective of the study are
shown. The variations and peaks observed in the following
figures were caused by the changing of conditions during
operation. These variations include changes in the quality
of the feed water and equipment failures. Laboratory results
were obtained 2 or more days after the samples were taken.
Operational conditions were adjusted once the results from
the lab were published (Figures 17–23).
CONCLUSIONS
Treatment of acidic waters through reverse osmosis mem-
branes is feasible, which will result in reducing the capital
costs required when compared to a conventional arrange-
ment. This new treatment is able to achieve the same levels
of sulfates in discharged water as a conventional arrange-
ment, meeting compliance of Peruvian and international
discharge standards.
ECA3=1000
ECA 1-A2=500
0
200
400
600
800
1,000
1,200
Sulfate (SO
4
-2 )
RO Permeate ECA 3 ECA 1 A2
Figure 17. Sulfates in RO permeate
4/11/
22
4/25/
22 5/9/2022
5/20/
22 6/1/2022 8/3/2022
8/15/
22
8/31/
22
9/12/
22
9/27/
22
10/7/
22
10/31
022
11/16
022
11/30
022
12/12
022
12/28
022
1/16/
23
1/27/
23
2/13/
23
3/13/
23
mg/L
It was demonstrated that depending on the quality of
the water to be treated, pH and lime addition from reac-
tor A1 to reactors B2 and B3 can be modified as part of a
continuous optimization of the process.
The optimal reaction times for each reactor was 30
minutes. The best sludge recirculation ratio (SRR) obtained
was 10:1. The sedimentation rates obtained from the mod-
ified Talmadge-Fitch Kynch tests were in the ranges of
((3.2–7.6 ft2 /(tone/day)). Sulfates in the discharge of the
thickener had concentrations of 2,000 mg/L.
When there is high sodium in the feed solution
(100 mg/L), the sodium cation reduces the precipitation
efficiency of sulfates as calcium sulfates, and increases the
optimum precipitation point from 2,000 mg/L to values
above 3,000 mg/L.
Results of the Sand Filter Process
The reverse osmosis permeate generated required additional
treatment, mainly to reduce arsenic.
Green sand was selected as the filter medium for this
purpose and was found to be effective. Washing with caus-
tic soda was sufficient and effective to sustain constant
operation of the green sands filter media.
Results of Biological Activity Analyses
The 17 different feed sources that fed the pilot plant were
analyzed as well as internal samples from the water treat-
ment process. A large variability of biological activity was
observed in these sources. The presence of biomasses were
not observed in the UF filtrate, which aligns with the
membranes filtration spectrum (Figures 25 and 26). The
discovery of biological masses in the feed water of the pilot
plant confirmed that the UF membranes had been fouled
by biological masses, because the UF is the first solid-liq-
uid separation step in the pilot plant process. This finding
requires two controls, first is source control of the biologi-
cal growth in the feed water and the second is an effective
cleaning procedure to remove biological masses from the
membranes. Figure 24 shows the biological activity of two
feed sources and the feed to the HDS process. The type 1
feed comes from a revegetated area, which is the source of
the highest concentrations of bio mass’s observed.
Produced Water Quality Results
Lab results demonstrated that it is possible to meet the tar-
get water quality parameters. In the following figures the
main parameters that were the objective of the study are
shown. The variations and peaks observed in the following
figures were caused by the changing of conditions during
operation. These variations include changes in the quality
of the feed water and equipment failures. Laboratory results
were obtained 2 or more days after the samples were taken.
Operational conditions were adjusted once the results from
the lab were published (Figures 17–23).
CONCLUSIONS
Treatment of acidic waters through reverse osmosis mem-
branes is feasible, which will result in reducing the capital
costs required when compared to a conventional arrange-
ment. This new treatment is able to achieve the same levels
of sulfates in discharged water as a conventional arrange-
ment, meeting compliance of Peruvian and international
discharge standards.
ECA3=1000
ECA 1-A2=500
0
200
400
600
800
1,000
1,200
Sulfate (SO
4
-2 )
RO Permeate ECA 3 ECA 1 A2
Figure 17. Sulfates in RO permeate
4/11/
22
4/25/
22 5/9/2022
5/20/
22 6/1/2022 8/3/2022
8/15/
22
8/31/
22
9/12/
22
9/27/
22
10/7/
22
10/31
022
11/16
022
11/30
022
12/12
022
12/28
022
1/16/
23
1/27/
23
2/13/
23
3/13/
23
mg/L