XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3505
proportional to the reaction time. For instance, the carbon-
ation efficiency was 5% after 2 hrs of carbonation reaction
and increased to 18% after 8 hrs of carbonation reaction at
105 °C operation temperature. The operating temperature
impacts on the extent and the rate of reaction, and the car-
bonation efficiency exhibited a steady increase with increase
in temperature and with time over the course of reaction.
The highest carbonation efficiency (68%) was recorded at
185°C after 8 hours of reaction with a steady decrease in
efficiency to 56%, 48%, 30% and 21% at 165°C, 145°C,
125°C and 105°C respectively. From the reaction kinetics
point of view, that the increase in temperature facilitates
acceleration in chemical reaction and the rate of diffusion
and transport of ions.
Comparing the result obtained without any inorganic
electrolyte additive with that obtained with 1M NaCl addi-
tive, no significant improvement in carbonation efficiency
was achieved with the additives of 1M of NaCl. Figure 5b
shows the results obtained using 1M sodium sulfate
(Na2SO4). It was found that the addition of sodium sulfate
(Na2SO4) had a significant impact in the carbonation
efficiency, especially at 165°C or higher. For instance, the
addition of 1 M Na2SO4 demonstrated the extent of car-
bonation reached an efficiency of 95% at 165°C and 185
°C, respectively, after 8 hours of reaction. The carbonation
efficiency was reduced to 85%, 55% and 24% at 145°C,
125°C, and 105°C, respectively after 8 hours of carbon-
ation reaction. It is evident that compared with the carbon-
ation efficiency obtained without the addition of Na2SO4
electrolyte, the carbonation efficiency for olivine minerals
obtained with 1M Na2SO4 was significantly improved,
particularly at 165 °C or higher.
Figure 6 shows SEM images of carbonated olivine min-
erals obtained with 1M Na2SO4. Despite the dominant
phase is the rhombohedral structured magnesite crystals,
some distinct features are evident with the use of Na2SO4
as additive. As shown, magnesite crystal forms clusters away
from the surface of original olivine minerals rather than on
the surface of original olivine minerals. These clusters cre-
ate islands, bonded by amorphous silica. The linkage by
amorphous silica is distinct from the baseline condition.
Such observation suggested different paths and variation on
the crystal growth of magnesite and diffusion of silicic acid
during dissolution of the silicate material obtained with
and without the addition of Na2SO4 electrolyte. Figure 6
shows the SEM images of unreacted olivine particles. It was
found that the surface texture of the olivine particles was
rough, characterized by distinct ridges, comparable to that
of the unreacted olivine particles. The surface of the unre-
acted silicate mineral does not have amorphous silica for-
mation, indicating a freshly exposed surface. All evidence
shown above suggests that the surface of olivine minerals is
exposed for continuous dissolution processes. The absence
of silica layers enhances the diffusion of divalent ions,
which are essential for the carbonation process.
Effect of Other Electrolytes
The comparison of different electrolytes on the mineral car-
bonation efficiency was conducted at 185°C, for 2 hours at
50 bar pCO2. When compared to this baseline, all tested
electrolytes show an increase in carbonation efficiency, sug-
gesting that the presence of these electrolytes plays a sig-
nificant role in enhancing the CO2 carbonation process.
The electrolytes can be categorized based on their impact
on carbonation efficiency. Sodium metasilicate (Na2SiO3)
and ammonium chloride (NH4Cl) showed minor improve-
ments over the baseline, with efficiencies of 43.93% and
46.09%, respectively. These slight enhancements suggest
Figure 5. Kinetics of carbonation efficiency at different operating temperatures in the range of 105–
185 °C with and without the addition of 1M Na
2 SO
4
proportional to the reaction time. For instance, the carbon-
ation efficiency was 5% after 2 hrs of carbonation reaction
and increased to 18% after 8 hrs of carbonation reaction at
105 °C operation temperature. The operating temperature
impacts on the extent and the rate of reaction, and the car-
bonation efficiency exhibited a steady increase with increase
in temperature and with time over the course of reaction.
The highest carbonation efficiency (68%) was recorded at
185°C after 8 hours of reaction with a steady decrease in
efficiency to 56%, 48%, 30% and 21% at 165°C, 145°C,
125°C and 105°C respectively. From the reaction kinetics
point of view, that the increase in temperature facilitates
acceleration in chemical reaction and the rate of diffusion
and transport of ions.
Comparing the result obtained without any inorganic
electrolyte additive with that obtained with 1M NaCl addi-
tive, no significant improvement in carbonation efficiency
was achieved with the additives of 1M of NaCl. Figure 5b
shows the results obtained using 1M sodium sulfate
(Na2SO4). It was found that the addition of sodium sulfate
(Na2SO4) had a significant impact in the carbonation
efficiency, especially at 165°C or higher. For instance, the
addition of 1 M Na2SO4 demonstrated the extent of car-
bonation reached an efficiency of 95% at 165°C and 185
°C, respectively, after 8 hours of reaction. The carbonation
efficiency was reduced to 85%, 55% and 24% at 145°C,
125°C, and 105°C, respectively after 8 hours of carbon-
ation reaction. It is evident that compared with the carbon-
ation efficiency obtained without the addition of Na2SO4
electrolyte, the carbonation efficiency for olivine minerals
obtained with 1M Na2SO4 was significantly improved,
particularly at 165 °C or higher.
Figure 6 shows SEM images of carbonated olivine min-
erals obtained with 1M Na2SO4. Despite the dominant
phase is the rhombohedral structured magnesite crystals,
some distinct features are evident with the use of Na2SO4
as additive. As shown, magnesite crystal forms clusters away
from the surface of original olivine minerals rather than on
the surface of original olivine minerals. These clusters cre-
ate islands, bonded by amorphous silica. The linkage by
amorphous silica is distinct from the baseline condition.
Such observation suggested different paths and variation on
the crystal growth of magnesite and diffusion of silicic acid
during dissolution of the silicate material obtained with
and without the addition of Na2SO4 electrolyte. Figure 6
shows the SEM images of unreacted olivine particles. It was
found that the surface texture of the olivine particles was
rough, characterized by distinct ridges, comparable to that
of the unreacted olivine particles. The surface of the unre-
acted silicate mineral does not have amorphous silica for-
mation, indicating a freshly exposed surface. All evidence
shown above suggests that the surface of olivine minerals is
exposed for continuous dissolution processes. The absence
of silica layers enhances the diffusion of divalent ions,
which are essential for the carbonation process.
Effect of Other Electrolytes
The comparison of different electrolytes on the mineral car-
bonation efficiency was conducted at 185°C, for 2 hours at
50 bar pCO2. When compared to this baseline, all tested
electrolytes show an increase in carbonation efficiency, sug-
gesting that the presence of these electrolytes plays a sig-
nificant role in enhancing the CO2 carbonation process.
The electrolytes can be categorized based on their impact
on carbonation efficiency. Sodium metasilicate (Na2SiO3)
and ammonium chloride (NH4Cl) showed minor improve-
ments over the baseline, with efficiencies of 43.93% and
46.09%, respectively. These slight enhancements suggest
Figure 5. Kinetics of carbonation efficiency at different operating temperatures in the range of 105–
185 °C with and without the addition of 1M Na
2 SO
4