XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 599
more precisely determine the energy captured or retained in
the slurry, the concentrate or the tailings.
Assumption 3
This is appropriate as most if not all typical equipment
found in mineral processing plants are not pressurized and
all fluids are incompressible.
Assumption 4
As with assumption 2, this is an appropriate assumption
in order to simplify the relationship. However, measuring
input and output temperatures would more precisely deter-
mine the energy captured or retained in slurry, concentra-
tion or tailings.
Assumption 5
This assumption is appropriate in the context of estimating
an upper limit to water loss through evaporation. However,
as noted previously, there is some energy lost by heat trans-
fer which would require a more in depth analysis of the
materials used, equipment dimensions as well as the heat
transfer properties of conduction, convection and radia-
tion. On the other hand, the general guidelines presented
here for increasing energy loss through heat transfer are
valid.
In summary, the definition of potential water loss as a
function of comminution energy input (see equation 14)
is valid. This defines an upper limit where all energy loss
by heat transfer has been eliminated (i.e., the whole pro-
cess is insulated). With respect to the use of the Dalton
equation (1), it would then define the lower limit for water
loss by evaporation. The actual water loss by evaporation
for a given plant would be somewhere between these two
limits. Determining more precisely where would require
further investigation to determine the magnitude of vary-
ing degrees of heat loss and more precisely determine site
specific water loss characteristics per equipment type.
Benefits
There are obvious social, cultural and environmental ben-
efits to reducing water loss in mineral processing. However,
the business benefit comes down to the net value that an
operation can generate by reducing the amount of water
lost through evaporation. The net value for mining opera-
tions in polar or near polar regions will be different from
those at or near the equator.
In polar or near polar regions, mineral processing
plants are packed into large, insulated buildings. The cost
of water is essentially zero as there is potentially plenty in
proximity to any mine. However, water loss by evaporation,
if not evacuated from these buildings, tends to condense,
and potential freeze on plant walls and roof especially dur-
ing winter months. To mitigate this, greater heating as well
as building ventilation is required. In addition, the pres-
ence of condensed water on inside building walls and struc-
tures contributes to infrastructure corrosion and associated
maintenance costs. As a result, the value of reduced water
loss through the measures described in this paper is mea-
sured by a reduction in energy use for building heating and
ventilation as well as reduced building maintenance costs
associated with corrosion.
In equatorial or near equatorial regions especially those
that are water stressed, access to water may require a coastal
desalination plant and pumping the desalinated water a
few hundred kilometers. In such cases, the cost of water is
related to desalination and pumping along with the associ-
ated operating costs. As a result, the value of reduced water
loss through the measures described in this paper is mea-
sured by a reduction in desalination, pumping and operat-
ing costs.
Potential Water Loss Metric
Knowing that potential water loss is a function of com-
minution energy, it becomes possible to revisit CEEC’s
energy curves (CEEC, 2023) and integrate a water loss
metric. Every comminution kWh in the CEEC energy
curve data can be first multiplied by 0.8 to determine the
heat energy captured by a given slurry followed by dividing
the enthalpy of evaporation and then multiplying the result
with water density. The resulting potential water loss curves
can be found in Figure 4.
It is important to note that contrary to the energy
curves, the cost or rather the value of water loss is not pro-
portional to specific water loss. The value of water loss is a
site-specific parameter and needs to be determined for each
site. As a result, it will have to be plotted independently of
the specific water loss data.
As mentioned, there are two limits to potential water
loss: the upper and the lower limit. The upper limit is plot-
ted in Figure 4. However, by gathering surface area data
on any open surface equipment and associated data in any
given process, it would be possible to add to these water loss
curves a lower limit value for potential water loss.
CONCLUSION
This work examined quantifying water loss in mineral pro-
cessing operations by leveraging thermodynamics. Based
on this analysis, which was limited to the processing plant,
the following observations have been made:
more precisely determine the energy captured or retained in
the slurry, the concentrate or the tailings.
Assumption 3
This is appropriate as most if not all typical equipment
found in mineral processing plants are not pressurized and
all fluids are incompressible.
Assumption 4
As with assumption 2, this is an appropriate assumption
in order to simplify the relationship. However, measuring
input and output temperatures would more precisely deter-
mine the energy captured or retained in slurry, concentra-
tion or tailings.
Assumption 5
This assumption is appropriate in the context of estimating
an upper limit to water loss through evaporation. However,
as noted previously, there is some energy lost by heat trans-
fer which would require a more in depth analysis of the
materials used, equipment dimensions as well as the heat
transfer properties of conduction, convection and radia-
tion. On the other hand, the general guidelines presented
here for increasing energy loss through heat transfer are
valid.
In summary, the definition of potential water loss as a
function of comminution energy input (see equation 14)
is valid. This defines an upper limit where all energy loss
by heat transfer has been eliminated (i.e., the whole pro-
cess is insulated). With respect to the use of the Dalton
equation (1), it would then define the lower limit for water
loss by evaporation. The actual water loss by evaporation
for a given plant would be somewhere between these two
limits. Determining more precisely where would require
further investigation to determine the magnitude of vary-
ing degrees of heat loss and more precisely determine site
specific water loss characteristics per equipment type.
Benefits
There are obvious social, cultural and environmental ben-
efits to reducing water loss in mineral processing. However,
the business benefit comes down to the net value that an
operation can generate by reducing the amount of water
lost through evaporation. The net value for mining opera-
tions in polar or near polar regions will be different from
those at or near the equator.
In polar or near polar regions, mineral processing
plants are packed into large, insulated buildings. The cost
of water is essentially zero as there is potentially plenty in
proximity to any mine. However, water loss by evaporation,
if not evacuated from these buildings, tends to condense,
and potential freeze on plant walls and roof especially dur-
ing winter months. To mitigate this, greater heating as well
as building ventilation is required. In addition, the pres-
ence of condensed water on inside building walls and struc-
tures contributes to infrastructure corrosion and associated
maintenance costs. As a result, the value of reduced water
loss through the measures described in this paper is mea-
sured by a reduction in energy use for building heating and
ventilation as well as reduced building maintenance costs
associated with corrosion.
In equatorial or near equatorial regions especially those
that are water stressed, access to water may require a coastal
desalination plant and pumping the desalinated water a
few hundred kilometers. In such cases, the cost of water is
related to desalination and pumping along with the associ-
ated operating costs. As a result, the value of reduced water
loss through the measures described in this paper is mea-
sured by a reduction in desalination, pumping and operat-
ing costs.
Potential Water Loss Metric
Knowing that potential water loss is a function of com-
minution energy, it becomes possible to revisit CEEC’s
energy curves (CEEC, 2023) and integrate a water loss
metric. Every comminution kWh in the CEEC energy
curve data can be first multiplied by 0.8 to determine the
heat energy captured by a given slurry followed by dividing
the enthalpy of evaporation and then multiplying the result
with water density. The resulting potential water loss curves
can be found in Figure 4.
It is important to note that contrary to the energy
curves, the cost or rather the value of water loss is not pro-
portional to specific water loss. The value of water loss is a
site-specific parameter and needs to be determined for each
site. As a result, it will have to be plotted independently of
the specific water loss data.
As mentioned, there are two limits to potential water
loss: the upper and the lower limit. The upper limit is plot-
ted in Figure 4. However, by gathering surface area data
on any open surface equipment and associated data in any
given process, it would be possible to add to these water loss
curves a lower limit value for potential water loss.
CONCLUSION
This work examined quantifying water loss in mineral pro-
cessing operations by leveraging thermodynamics. Based
on this analysis, which was limited to the processing plant,
the following observations have been made: