XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 169
of comminution characteristics maintained by Alex Doll
(Doll, 2016). As a very broad generalisation, olivine-rich
ultramafic rocks (adcumulates and dunites) appear to be
relatively dense, moderately competent and medium-hard
to hard. The abrasiveness is generally comparatively low but
this depends on the level of alteration of the rock (serpenti-
nization leading to lower abrasiveness).
Specific energy requirements were based on power-
based modelling (Ausgrind see Lane et al., 2016). The
influence of the %conversion—grind size relationship on
the carbonation performance will be investigated later in
this paper.
A breakdown of emissions is shown in Figure 5. CO2
emission of approximately 1732 t estimated were esti-
mated for the construction of a 100 t/h milling plant.
This is equivalent to 0.73 kg CO2/t ore assuming a three
year amortisation of emissions, which is over an order of
magnitude lower than the estimated comminution CO2
emissions (52.0 kg CO2/t ore see below).
The estimated capture capacity of the dunite based on
an olivine content of 90% is around 567 kg CO2/t ore. The
mining process is estimated to account for 4.8 kg CO2/t
ore and processing adds up to around 52.0 kg CO2/t
ore, of which the majority is consumed as energy in the
grinding process (roughly equal splits between power and
media-related emissions). With total CO2 emissions from
the milling process adding up to 57.5 kg CO2/t ore, the net
carbon capture capacity of olivine is estimated to be in the
region of 510 kg CO2/t ore. This is a significant net capture
capacity, though it is important to point out that this cal-
culation does not account for possible emissions associated
with the downstream carbonation reaction, for instance
due to having to build up a high pressure/low temperature
environment to achieve optimum CO2 solubility.
Another important point is that, for effective car-
bonation, a highly concentrated CO2 stream is required.
Technologies such as Direct Air Capture (DAC) for CO2
extraction from the atmosphere are still in their infancy, so
in reality a carbonation plant should be sited near a ready
source of concentrated CO2. Plants burning fossil fuels are
the obvious candidate, but there are industrial processes
that also emit large amounts of CO2. A good example that
may be encountered at mining operations is a neutralisa-
tion reaction using calcrete or limestone.
Table 4. 80th Percentile comminution characteristics for
ultramafic rock
Comminution Characteristic Ultramafic Rock
A*b value 45.2
Bond Crusher Work Index 16.1
Bond Rod Mill Work Index 16.4
Bond Ball Mill Work Index 22.1
Abrasion Index 0.29
Specific Gravity 3.00
0.7
4.8
25.8
3.8
3.6
Construction Mining
Grinding Consumables (grinding)
Ancilliary equipment
Figure 5. Breakdown of emissions associated with the comminution process
of comminution characteristics maintained by Alex Doll
(Doll, 2016). As a very broad generalisation, olivine-rich
ultramafic rocks (adcumulates and dunites) appear to be
relatively dense, moderately competent and medium-hard
to hard. The abrasiveness is generally comparatively low but
this depends on the level of alteration of the rock (serpenti-
nization leading to lower abrasiveness).
Specific energy requirements were based on power-
based modelling (Ausgrind see Lane et al., 2016). The
influence of the %conversion—grind size relationship on
the carbonation performance will be investigated later in
this paper.
A breakdown of emissions is shown in Figure 5. CO2
emission of approximately 1732 t estimated were esti-
mated for the construction of a 100 t/h milling plant.
This is equivalent to 0.73 kg CO2/t ore assuming a three
year amortisation of emissions, which is over an order of
magnitude lower than the estimated comminution CO2
emissions (52.0 kg CO2/t ore see below).
The estimated capture capacity of the dunite based on
an olivine content of 90% is around 567 kg CO2/t ore. The
mining process is estimated to account for 4.8 kg CO2/t
ore and processing adds up to around 52.0 kg CO2/t
ore, of which the majority is consumed as energy in the
grinding process (roughly equal splits between power and
media-related emissions). With total CO2 emissions from
the milling process adding up to 57.5 kg CO2/t ore, the net
carbon capture capacity of olivine is estimated to be in the
region of 510 kg CO2/t ore. This is a significant net capture
capacity, though it is important to point out that this cal-
culation does not account for possible emissions associated
with the downstream carbonation reaction, for instance
due to having to build up a high pressure/low temperature
environment to achieve optimum CO2 solubility.
Another important point is that, for effective car-
bonation, a highly concentrated CO2 stream is required.
Technologies such as Direct Air Capture (DAC) for CO2
extraction from the atmosphere are still in their infancy, so
in reality a carbonation plant should be sited near a ready
source of concentrated CO2. Plants burning fossil fuels are
the obvious candidate, but there are industrial processes
that also emit large amounts of CO2. A good example that
may be encountered at mining operations is a neutralisa-
tion reaction using calcrete or limestone.
Table 4. 80th Percentile comminution characteristics for
ultramafic rock
Comminution Characteristic Ultramafic Rock
A*b value 45.2
Bond Crusher Work Index 16.1
Bond Rod Mill Work Index 16.4
Bond Ball Mill Work Index 22.1
Abrasion Index 0.29
Specific Gravity 3.00
0.7
4.8
25.8
3.8
3.6
Construction Mining
Grinding Consumables (grinding)
Ancilliary equipment
Figure 5. Breakdown of emissions associated with the comminution process