XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 115
supply and security may introduce speed-humps of their
own, well beyond the scope of this paper.
Water Considerations
The considerations of water availability, use and compe-
tition present challenges that are pivotal to the ability to
mine and deploy processing and to therefore support the
energy transition.
If water stress, as defined as the ratio of water demand
to renewable supply (WRI, 2023), is overlain with the
density of mining operations, there are certainly areas of
extreme water stress that also have higher density of mining
operations. The graphic in Figure 5 is not definitive, as it
assigns water stress on a per country basis, but it shows that
there are countries where there is the potential for water
competition, in an already stressed area.
In terms of prioritization for water access, it is clear
that supply to residences, farmers and small business all
rank above mining.
The practical implications, both for water management
and water recovery are considerable and in terms of commi-
nution, one aspect is the move towards dry stacked tailings
(DST). Obviously, liberation and recovery cannot be com-
promised simply to engineer a size distribution for DST,
so options including co-disposal of dewatered tailings and
mine waste rock are key to the development of stable and
sustainable DST. Given that the stability and geotechnical
behavior of a DST formation is critically linked to the size
distribution and packing, there may be a case for consid-
ering what level of comminution is required for the mine
waste rock component.
Beyond comminution, there are also a range of impli-
cations beyond the direct scope of this paper, but as an
example, running at higher than usual slurry densities in
order to drop water demand can have significant implica-
tions on processes, including loss of recovery in flotation.
COMMINUTION AS PART OF AN
OVERALL SYSTEM
If the overall mining and processing system is considered,
initiatives aimed at energy and water reduction, generally
fall into broad categories:
• In-situ methods, including chemical leaching
– Chemical leaching is limited to well defined
porous structures, with natural geological barriers
to prevent reagents dispersing, such as some ura-
nium operations.
• High resolution mining to minimize dilution
– Use in hard rock is limited by the scale of extrac-
tion that can be achieved, mechanical constraints,
ground conditions and type of ore body.
• Preconcentration (post mining)
– Various options available, i.e., size, bulk, particle,
but limited deployments.
• Coarse Particle Liberation:
– Highly dependent on mineralogy and liberation
state, but more equipment is now available.
• Dry grinding:
– Only saves water if preconcentration process is dry
and mass is rejected prior to wet subsequent pro-
cessing. Use of HPGR plus air classification, with
waste rejection included through magnetic separa-
tion (i.e., Iron Bridge).
Source: Zhou et al. 2023
Figure 4. Projected baseload electricity prices for EU27 and CH, NO and UK, in Euro(2020)/MWhr
supply and security may introduce speed-humps of their
own, well beyond the scope of this paper.
Water Considerations
The considerations of water availability, use and compe-
tition present challenges that are pivotal to the ability to
mine and deploy processing and to therefore support the
energy transition.
If water stress, as defined as the ratio of water demand
to renewable supply (WRI, 2023), is overlain with the
density of mining operations, there are certainly areas of
extreme water stress that also have higher density of mining
operations. The graphic in Figure 5 is not definitive, as it
assigns water stress on a per country basis, but it shows that
there are countries where there is the potential for water
competition, in an already stressed area.
In terms of prioritization for water access, it is clear
that supply to residences, farmers and small business all
rank above mining.
The practical implications, both for water management
and water recovery are considerable and in terms of commi-
nution, one aspect is the move towards dry stacked tailings
(DST). Obviously, liberation and recovery cannot be com-
promised simply to engineer a size distribution for DST,
so options including co-disposal of dewatered tailings and
mine waste rock are key to the development of stable and
sustainable DST. Given that the stability and geotechnical
behavior of a DST formation is critically linked to the size
distribution and packing, there may be a case for consid-
ering what level of comminution is required for the mine
waste rock component.
Beyond comminution, there are also a range of impli-
cations beyond the direct scope of this paper, but as an
example, running at higher than usual slurry densities in
order to drop water demand can have significant implica-
tions on processes, including loss of recovery in flotation.
COMMINUTION AS PART OF AN
OVERALL SYSTEM
If the overall mining and processing system is considered,
initiatives aimed at energy and water reduction, generally
fall into broad categories:
• In-situ methods, including chemical leaching
– Chemical leaching is limited to well defined
porous structures, with natural geological barriers
to prevent reagents dispersing, such as some ura-
nium operations.
• High resolution mining to minimize dilution
– Use in hard rock is limited by the scale of extrac-
tion that can be achieved, mechanical constraints,
ground conditions and type of ore body.
• Preconcentration (post mining)
– Various options available, i.e., size, bulk, particle,
but limited deployments.
• Coarse Particle Liberation:
– Highly dependent on mineralogy and liberation
state, but more equipment is now available.
• Dry grinding:
– Only saves water if preconcentration process is dry
and mass is rejected prior to wet subsequent pro-
cessing. Use of HPGR plus air classification, with
waste rejection included through magnetic separa-
tion (i.e., Iron Bridge).
Source: Zhou et al. 2023
Figure 4. Projected baseload electricity prices for EU27 and CH, NO and UK, in Euro(2020)/MWhr