XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3415
Staged Roasting and Water Leaching
To enhance the Li recovery in water leaching and avoid
following acid leaching for Li recovery, a staged roasting
and water leaching approach was formulated as an effective
sustainable means for Li recovery (Rezaee and Subasinghe,
2024). Consequently, a patent-pending two-stage roast-
ing and water leaching process was carried out to recover
Li through water leaching. Figure 9 illustrates Li recovery
results from the two-staged roasting process, with vari-
ous NaOH-to-stage one leaching residue (R) ratios. As
the NaOH-to-R ratio increased from 0.25: R to 1.5: R,
Li recovery exhibited a significant rise, surging from 85%
to 99% (Figure 9). Subsequently, the final leaching residue
obtained after stage two leaching was characterized through
XRD, as displayed in Figure 10. This residue displayed par-
tial crystallinity of remaining silicate material, indicated by
the presence of a broad amorphous peak spanning from
10° to 40°. Furthermore, the XRD pattern revealed the
presence of peaks corresponding to NaAlSi2O6, Na2SiO3,
Na2Si2O5, SiO2, Al(OH)3, and AlO(OH). Notably, the
α-spodumene or any peaks corresponding to Li-containing
species were not observed, confirming the complete conver-
sion of α-spodumene into water-soluble phases (Rezaee and
Subasinghe, 2024). Moreover, the detection of Al(OH)3
and AlO(OH) peaks in Figure 10 further substantiates
the low Al recovery. This provides further evidence that
the stage one dissolution reaction follows a shrinking core
model, but a single roasting step does not completely pen-
etrate to the core of the particle.
CONCLUSIONS
In conclusion, this study presents a comprehensive inves-
tigation into the optimization of a novel process for the
direct extraction of Li from α-spodumene. During the
roasting phase, the study demonstrated that the NaOH-
to-α-spodumene ratio, roasting temperature, and roasting
duration significantly influence Li extraction. An optimal
NaOH-to-α-spodumene ratio of 1.5:1, a roasting tempera-
ture of 325 °C, and a roasting duration of 2 hours were
identified as the most effective conditions for maximizing
Li recovery. In the water leaching phase, factors such as stir-
ring rate, solid-to-liquid ratio, and leaching temperature
were investigated. It was found that stirring rate had mini-
mal impact on Li recovery. A solid-to-liquid ratio of 10%
was identified as the optimal condition for Li dissolution,
while increasing leaching temperature resulted in decreased
Li recovery. To further enhance Li recovery, a staged roast-
ing and water leaching approach was employed. This
approach proved highly effective, with Li recovery reach-
ing up to 99% when increasing the NaOH-to-stage one
leach residue ratio. XRD analysis of the final leach residue
confirmed the complete conversion of α-spodumene into
water-soluble phases, further validating the efficiency of the
process. This research provides a sustainable and innovative
Figure 9. Stage roasting and water leaching of α-spodumene (R – leach residue of stage one roasting and
water leaching at optimum conditions)
Staged Roasting and Water Leaching
To enhance the Li recovery in water leaching and avoid
following acid leaching for Li recovery, a staged roasting
and water leaching approach was formulated as an effective
sustainable means for Li recovery (Rezaee and Subasinghe,
2024). Consequently, a patent-pending two-stage roast-
ing and water leaching process was carried out to recover
Li through water leaching. Figure 9 illustrates Li recovery
results from the two-staged roasting process, with vari-
ous NaOH-to-stage one leaching residue (R) ratios. As
the NaOH-to-R ratio increased from 0.25: R to 1.5: R,
Li recovery exhibited a significant rise, surging from 85%
to 99% (Figure 9). Subsequently, the final leaching residue
obtained after stage two leaching was characterized through
XRD, as displayed in Figure 10. This residue displayed par-
tial crystallinity of remaining silicate material, indicated by
the presence of a broad amorphous peak spanning from
10° to 40°. Furthermore, the XRD pattern revealed the
presence of peaks corresponding to NaAlSi2O6, Na2SiO3,
Na2Si2O5, SiO2, Al(OH)3, and AlO(OH). Notably, the
α-spodumene or any peaks corresponding to Li-containing
species were not observed, confirming the complete conver-
sion of α-spodumene into water-soluble phases (Rezaee and
Subasinghe, 2024). Moreover, the detection of Al(OH)3
and AlO(OH) peaks in Figure 10 further substantiates
the low Al recovery. This provides further evidence that
the stage one dissolution reaction follows a shrinking core
model, but a single roasting step does not completely pen-
etrate to the core of the particle.
CONCLUSIONS
In conclusion, this study presents a comprehensive inves-
tigation into the optimization of a novel process for the
direct extraction of Li from α-spodumene. During the
roasting phase, the study demonstrated that the NaOH-
to-α-spodumene ratio, roasting temperature, and roasting
duration significantly influence Li extraction. An optimal
NaOH-to-α-spodumene ratio of 1.5:1, a roasting tempera-
ture of 325 °C, and a roasting duration of 2 hours were
identified as the most effective conditions for maximizing
Li recovery. In the water leaching phase, factors such as stir-
ring rate, solid-to-liquid ratio, and leaching temperature
were investigated. It was found that stirring rate had mini-
mal impact on Li recovery. A solid-to-liquid ratio of 10%
was identified as the optimal condition for Li dissolution,
while increasing leaching temperature resulted in decreased
Li recovery. To further enhance Li recovery, a staged roast-
ing and water leaching approach was employed. This
approach proved highly effective, with Li recovery reach-
ing up to 99% when increasing the NaOH-to-stage one
leach residue ratio. XRD analysis of the final leach residue
confirmed the complete conversion of α-spodumene into
water-soluble phases, further validating the efficiency of the
process. This research provides a sustainable and innovative
Figure 9. Stage roasting and water leaching of α-spodumene (R – leach residue of stage one roasting and
water leaching at optimum conditions)