XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 633
membranes. This needs to be achieved while concurrently
avoiding gypsum scaling. Producing a water quality that
meets the highest national and international quality stan-
dards is required, while also optimizing both capital and
operating investment costs.
METHODOLOGY
The methodology used to demonstrate the viability of this
process was the installation of a pilot plant at the Newmont
Yanacocha mining unit, which operated at a capacity of 2
m3/h. The data from each of the pilot plant’s operational
processes and controls were collected in Excel spreadsheets
where graphs for the analysis of the results were constructed.
This pilot plant operated for two years, and applied the fol-
lowing treatment technologies:
• Ultrafiltration (UF)
• Reverse Osmosis (RO)
• High sludge density (HDS) and
• Sand filters (SF)
Ultrafiltration
The physical process of the separation of solids contained in a
liquid by membranes using hydrostatic pressure to force the
passage of water through a semipermeable membrane. This
process produces two streams, a filtrate and a concentrate.
Ultrafiltration is a process commonly installed as a pretreat-
ment prior to RO because RO processes requires a solution
without any solids in the feed solution. The main parameters
monitored in the UF process during the piloting were:
• Flow in the feed and filtrated streams
• Turbidity in the feed and filtered solution
• Pressure differentials
• Flux =Flow per membrane area
• Washing cycles
• Time between required wash cycles
• Characterization of the feed solution (pH, SO4 and
metals)
• Biological activity
Reverse Osmosis:
The physical-chemical process of the separation of metals
and chemical compounds in an ionic state contained in a
liquid phase by membranes using hydrostatic pressure to
force the passage of water through a semipermeable mem-
brane. In RO treatment, two streams occur, the permeate
and the concentrate. The permeate which is the treated
water contains low dissolved solutes and the concentrate
stream, which is the flow that fails passing the membrane
and contains the rejected solution with high dissolved sol-
utes. The main parameters monitored in this RO process
during the piloting were:
• Flow of feed and permeate streams
• Recovery =Feed Flow /Permeate Flow
• Feed temperature
• Conductivity in the feed and permeate streams.
• Pressure differentials
• Flux =Flow per membrane area
• Washing cycles
• Characterization of the feed, permeate and concen-
trate solutions (pH, SO4 and metals)
• Biological activity
High Density of Sludge:
Is the process of precipitating metals in the form of hydrox-
ides and sulfates which is caused by the addition of hydrated
calcium hydroxide, also known as milk of lime. It is pos-
sible to obtain a sludge containing between 20 to 40%
solids as a result of sludge recycling, though an adequate
recirculation of the sludge is required. In Figure 5, the best
configuration obtained from the pilot operation is shown.
The main parameters monitored in the HDS process dur-
ing the piloting were:
• Flow in the feed and thickener discharge
• %solids
• pH in precipitation reactors
• Sludge recirculation flows
Reverse
Osmosis
Acid rock drainage
(filtrated from ultrafiltration
With dissolved solutes)
Concentrate
(concentrated in dissolved solutes)
Permeate
(low dissolved solutes)
Figure 3. Reverse Osmosis Process
Ultrafiltration
Acid rock drainage
(with solids)
Concentrate
(concentrated in solids)
Filtrated
(no solids)
Figure 2. Ultrafiltration Process
membranes. This needs to be achieved while concurrently
avoiding gypsum scaling. Producing a water quality that
meets the highest national and international quality stan-
dards is required, while also optimizing both capital and
operating investment costs.
METHODOLOGY
The methodology used to demonstrate the viability of this
process was the installation of a pilot plant at the Newmont
Yanacocha mining unit, which operated at a capacity of 2
m3/h. The data from each of the pilot plant’s operational
processes and controls were collected in Excel spreadsheets
where graphs for the analysis of the results were constructed.
This pilot plant operated for two years, and applied the fol-
lowing treatment technologies:
• Ultrafiltration (UF)
• Reverse Osmosis (RO)
• High sludge density (HDS) and
• Sand filters (SF)
Ultrafiltration
The physical process of the separation of solids contained in a
liquid by membranes using hydrostatic pressure to force the
passage of water through a semipermeable membrane. This
process produces two streams, a filtrate and a concentrate.
Ultrafiltration is a process commonly installed as a pretreat-
ment prior to RO because RO processes requires a solution
without any solids in the feed solution. The main parameters
monitored in the UF process during the piloting were:
• Flow in the feed and filtrated streams
• Turbidity in the feed and filtered solution
• Pressure differentials
• Flux =Flow per membrane area
• Washing cycles
• Time between required wash cycles
• Characterization of the feed solution (pH, SO4 and
metals)
• Biological activity
Reverse Osmosis:
The physical-chemical process of the separation of metals
and chemical compounds in an ionic state contained in a
liquid phase by membranes using hydrostatic pressure to
force the passage of water through a semipermeable mem-
brane. In RO treatment, two streams occur, the permeate
and the concentrate. The permeate which is the treated
water contains low dissolved solutes and the concentrate
stream, which is the flow that fails passing the membrane
and contains the rejected solution with high dissolved sol-
utes. The main parameters monitored in this RO process
during the piloting were:
• Flow of feed and permeate streams
• Recovery =Feed Flow /Permeate Flow
• Feed temperature
• Conductivity in the feed and permeate streams.
• Pressure differentials
• Flux =Flow per membrane area
• Washing cycles
• Characterization of the feed, permeate and concen-
trate solutions (pH, SO4 and metals)
• Biological activity
High Density of Sludge:
Is the process of precipitating metals in the form of hydrox-
ides and sulfates which is caused by the addition of hydrated
calcium hydroxide, also known as milk of lime. It is pos-
sible to obtain a sludge containing between 20 to 40%
solids as a result of sludge recycling, though an adequate
recirculation of the sludge is required. In Figure 5, the best
configuration obtained from the pilot operation is shown.
The main parameters monitored in the HDS process dur-
ing the piloting were:
• Flow in the feed and thickener discharge
• %solids
• pH in precipitation reactors
• Sludge recirculation flows
Reverse
Osmosis
Acid rock drainage
(filtrated from ultrafiltration
With dissolved solutes)
Concentrate
(concentrated in dissolved solutes)
Permeate
(low dissolved solutes)
Figure 3. Reverse Osmosis Process
Ultrafiltration
Acid rock drainage
(with solids)
Concentrate
(concentrated in solids)
Filtrated
(no solids)
Figure 2. Ultrafiltration Process