598 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
fins to these surfaces can increase heat transfer rates (Q
heat
o
)by 30% to 50% (Abbas &Wang, 2020 Frederick &
Samper, 2010 Mokhtari et al., 2017 R et al., 2021 Saqr
&Musa, 2009).
7. Filters
It is known that the amount of water removed by filter-
ing increases with a coarser grind. In addition, a coarser
grind reduces the amount energy consumed in grinding.
However, a coarser grind will undoubtedly increase the
amount of valued mineral being lost to the tailings. As a
result, it is doubtful that coarser grinds will be adopted in
the near future as a means to reduce water loss.
On the other hand, there are tailings treatment pro-
cess technologies that are being explored that may alleviate
the hesitancy to grind courser. One such process technol-
ogy (Radziszewski and Blum, 2023, 2024 Radziszewski,
2023a, 2023b) is electrochemical in nature and aims to
remove all sulphide minerals from a massive sulphide ore,
capture that value along with hydrogen and electricity by-
products. If successful, the use of such tailings treatment
process technologies could motivate a faster transition to
not only coarser grinds, but potentially dry processing.
8. Tailings
Although outside of the initial plant control volume
description, traditional tailings ponds are a source of both
recycled water for the plant as well as water loss due to
evaporation. If all the energy captured in the slurry has
been dissipated by the time tailings discharge is reached,
then the only source of heat to a tailings pond will be the
sun. As a result, the Dalton equation (equation 1), which
is a function of interdependent variable of humidity, sur-
face area and wind speed over that surface, can be used to
estimate the water loss by evaporation. This suggests that
covering the water surface area of a tailings facility would
reduce if not eliminate the pond’s surface area. Such a cover
would also eliminate the impact of wind speed which in
turn would greatly reduce water loss by evaporation.
9. Dry Processing
Substituting a dry grinding process for the wet grinding
process found in Figure 2 would also require a wet condi-
tioning process preceding flotation. The resulting potential
water loss for a control volume defined around the dry cir-
cuit would be, by equation (14), equal to zero. A dry HPGR
is 25% to 30% more energy efficient than a wet SAG mill
(Rosario &Hall, 2010). A dry VRM is documented as
being almost 50% more energy efficiency than a wet ball
mill (Swart, 2020 Swart et al., 2022). Furthermore, if
development efforts succeed for comminution technologies
such as the conjugate anvil hammer mill (Li et al., 2019
Wilson et al., 2023) or the ARBS mill (ARBS, 2024), it
is possible to suggest up to 80% reductions in energy use
for the same grind duty increasing grinding efficiency yet
again. Consequently, the potential water loss for a plant
having a more efficient dry grinding circuit will be signifi-
cantly less than a wet processing plant.
In addition, pneumatic fines transport will increase
heat loss from the ore while adding fins to any large surface
will further increase heat loss (Q
heat
o ).
Subsequent mixing of the dry warm ore with cooler
plant water will diffuse the remaining heat in the slurry and
bring the energy content to that of the baseline environ-
ment. As most if not all of the energy input into the ore
through comminution has been lost or dissipated, the main
driver of evaporation will be water surface area through any
free surface present in the process such as that found in flo-
tation, thickening, and the like. As a result, the wet condi-
tioning process along with subsequent processes having free
surfaces will need heat exchanger covers to reduce further
potential water loss.
DISCUSSION
Limitations
The limitations to the development and eventual use of
equations (4) to (14) resides in the validity of the assump-
tions used.
Assumption 1
Using Gunson’s (Gunson et al., 2012) results for the 50,000
t/day, it is expected that some 116,667 m3/day of water
is required. From Table 1, the daily tonnage for Cadia is
49,560 t/day and for Canadian Malartic is 55,000 t/day
which is somewhat similar to that of the Gunson plant.
Assuming the water requirements in processing are also
similar, then the potential water loss through evaporation
would be 0.8% and 1.3% respectively. Assumption 1 is
considered valid.
This approximate 1% defines the upper limit of poten-
tial daily water loss. Assuming that 1% of the plant’s
116,667 m3/day (1166.7 m3/day) water requirement is lost
every day, over a year, the loss would be about 425,800 m3/
yr (365 × 1,166.7 m3/day) which is 3.65 times the daily
water requirement of the plant.
Assumption 2
This is appropriate in order to simplify the relationship.
However, measuring input and output temperatures would
fins to these surfaces can increase heat transfer rates (Q
heat
o
)by 30% to 50% (Abbas &Wang, 2020 Frederick &
Samper, 2010 Mokhtari et al., 2017 R et al., 2021 Saqr
&Musa, 2009).
7. Filters
It is known that the amount of water removed by filter-
ing increases with a coarser grind. In addition, a coarser
grind reduces the amount energy consumed in grinding.
However, a coarser grind will undoubtedly increase the
amount of valued mineral being lost to the tailings. As a
result, it is doubtful that coarser grinds will be adopted in
the near future as a means to reduce water loss.
On the other hand, there are tailings treatment pro-
cess technologies that are being explored that may alleviate
the hesitancy to grind courser. One such process technol-
ogy (Radziszewski and Blum, 2023, 2024 Radziszewski,
2023a, 2023b) is electrochemical in nature and aims to
remove all sulphide minerals from a massive sulphide ore,
capture that value along with hydrogen and electricity by-
products. If successful, the use of such tailings treatment
process technologies could motivate a faster transition to
not only coarser grinds, but potentially dry processing.
8. Tailings
Although outside of the initial plant control volume
description, traditional tailings ponds are a source of both
recycled water for the plant as well as water loss due to
evaporation. If all the energy captured in the slurry has
been dissipated by the time tailings discharge is reached,
then the only source of heat to a tailings pond will be the
sun. As a result, the Dalton equation (equation 1), which
is a function of interdependent variable of humidity, sur-
face area and wind speed over that surface, can be used to
estimate the water loss by evaporation. This suggests that
covering the water surface area of a tailings facility would
reduce if not eliminate the pond’s surface area. Such a cover
would also eliminate the impact of wind speed which in
turn would greatly reduce water loss by evaporation.
9. Dry Processing
Substituting a dry grinding process for the wet grinding
process found in Figure 2 would also require a wet condi-
tioning process preceding flotation. The resulting potential
water loss for a control volume defined around the dry cir-
cuit would be, by equation (14), equal to zero. A dry HPGR
is 25% to 30% more energy efficient than a wet SAG mill
(Rosario &Hall, 2010). A dry VRM is documented as
being almost 50% more energy efficiency than a wet ball
mill (Swart, 2020 Swart et al., 2022). Furthermore, if
development efforts succeed for comminution technologies
such as the conjugate anvil hammer mill (Li et al., 2019
Wilson et al., 2023) or the ARBS mill (ARBS, 2024), it
is possible to suggest up to 80% reductions in energy use
for the same grind duty increasing grinding efficiency yet
again. Consequently, the potential water loss for a plant
having a more efficient dry grinding circuit will be signifi-
cantly less than a wet processing plant.
In addition, pneumatic fines transport will increase
heat loss from the ore while adding fins to any large surface
will further increase heat loss (Q
heat
o ).
Subsequent mixing of the dry warm ore with cooler
plant water will diffuse the remaining heat in the slurry and
bring the energy content to that of the baseline environ-
ment. As most if not all of the energy input into the ore
through comminution has been lost or dissipated, the main
driver of evaporation will be water surface area through any
free surface present in the process such as that found in flo-
tation, thickening, and the like. As a result, the wet condi-
tioning process along with subsequent processes having free
surfaces will need heat exchanger covers to reduce further
potential water loss.
DISCUSSION
Limitations
The limitations to the development and eventual use of
equations (4) to (14) resides in the validity of the assump-
tions used.
Assumption 1
Using Gunson’s (Gunson et al., 2012) results for the 50,000
t/day, it is expected that some 116,667 m3/day of water
is required. From Table 1, the daily tonnage for Cadia is
49,560 t/day and for Canadian Malartic is 55,000 t/day
which is somewhat similar to that of the Gunson plant.
Assuming the water requirements in processing are also
similar, then the potential water loss through evaporation
would be 0.8% and 1.3% respectively. Assumption 1 is
considered valid.
This approximate 1% defines the upper limit of poten-
tial daily water loss. Assuming that 1% of the plant’s
116,667 m3/day (1166.7 m3/day) water requirement is lost
every day, over a year, the loss would be about 425,800 m3/
yr (365 × 1,166.7 m3/day) which is 3.65 times the daily
water requirement of the plant.
Assumption 2
This is appropriate in order to simplify the relationship.
However, measuring input and output temperatures would