3372 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
complex ions with all the 5 elements of interest, the reason
why there is no selectivity among these elements. On the
other hand, while sulfuric acid has a high dissolution for
Li (above 90% in 1 hour), the recovery for calcium is con-
siderably low (below 20%). While citric acid had calcium
as its best-extracted metal, it was the opposite for sulfuric
acid, making sulfuric acid preferable to citric acid in terms
of selective Li leaching.
Tartaric Acid
Tartaric acid, also known as 2,3-dihydroxy-succinic acid,
demonstrates a water solubility of 1330 g L−1 in water and
serves as a versatile molecule with at least three distinct
anion forms: neutral bi-acid, mono tartrate, and bitartrate
forms. It is naturally occurring in fruits like pineapples and
grapes, and is abundant in wine and vinegars, tartaric acid
gives a taste akin to citric acid but is smoother and has a
prolonged duration [41]. This characteristic highlights its
broader buffering range, spanning pH levels from 2.1 to
7.4, surpassing that of citric acid. Notably, tartaric acid
and its derivatives find significant applications in synthesiz-
ing various organic compounds due to their role as chiral
reagents [35].
The leaching experiments with tartaric acid were per-
formed. As shown in Figure 6, the extraction efficiency was
determined at specific time intervals for the five elements
of interest. Li extraction increased as time increased but did
not achieve up to 85% in the 24th hour. Concomitant Mg
followed a similar trend at a similar rate, just as observed
with citric acid. This only solidifies the findings of Thomas
Benson [42, 43] suggesting the concomitant nature of the
Li and Mg. Also, for Ca, more than 60% was extracted in 4
hours, with a slight increase as time increased from 4 hours
to 24 hours, leading to a maximum of about 70% for Ca.
Fe and Al followed a similar trend with a maximum extrac-
tion of around 58%.
Between tartaric acid and sulfuric acid, it can be seen
that tartaric acid has a lower leaching efficiency for Li, and
the selectivity for Li to other elements is low. It could be
suggested that this tendency is a result of the complex ions
formed between tartaric acid and the elements of interest,
permitting the considerable dissolution of all of them with-
out any selectivity. Sulfuric acid has a lower Ca extraction,
making it a selective reagent compared to tartaric acid.
Oxalic Acid
Oxalic acid, also known as ethanedioic acid, can be gen-
erated either through biological or commercial means,
with fungi, including white rots, brown rots, mycorrhizae,
plant pathogens, and Aspergillus niger (A.niger), being
the primary source. In the biological method, glucose is
transformed into oxalic and acetic acids through fungal
metabolism at pH values of 4.5–5, while in the commercial
method, oxaloacetate undergoes hydrolysis to yield oxalic
and acetic acids. It’s important to note that the solubility of
oxalic acid in water is 143 g L−1 [35].
Oxalic acid leaching was conducted under the same
conditions as the other acids, paying attention to the 5
main elements of interest, as depicted in Figure 7. Li had
a considerable extraction of about 90% in 1 hour, and
after 4 hours, there was no significant change in the extrac-
tions. Following Li was Al which consistently increased as
0
20
40
60
80
100
0 4 8 12 16 20 24 28
Time, hour
Citric Acid
Al
Ca
Fe
Li
Mg
Figure 5. Dissolution rates of main elements in claystone using citric acid. 1M acid, 80
°C, 10 L/S
Extraction,
%
complex ions with all the 5 elements of interest, the reason
why there is no selectivity among these elements. On the
other hand, while sulfuric acid has a high dissolution for
Li (above 90% in 1 hour), the recovery for calcium is con-
siderably low (below 20%). While citric acid had calcium
as its best-extracted metal, it was the opposite for sulfuric
acid, making sulfuric acid preferable to citric acid in terms
of selective Li leaching.
Tartaric Acid
Tartaric acid, also known as 2,3-dihydroxy-succinic acid,
demonstrates a water solubility of 1330 g L−1 in water and
serves as a versatile molecule with at least three distinct
anion forms: neutral bi-acid, mono tartrate, and bitartrate
forms. It is naturally occurring in fruits like pineapples and
grapes, and is abundant in wine and vinegars, tartaric acid
gives a taste akin to citric acid but is smoother and has a
prolonged duration [41]. This characteristic highlights its
broader buffering range, spanning pH levels from 2.1 to
7.4, surpassing that of citric acid. Notably, tartaric acid
and its derivatives find significant applications in synthesiz-
ing various organic compounds due to their role as chiral
reagents [35].
The leaching experiments with tartaric acid were per-
formed. As shown in Figure 6, the extraction efficiency was
determined at specific time intervals for the five elements
of interest. Li extraction increased as time increased but did
not achieve up to 85% in the 24th hour. Concomitant Mg
followed a similar trend at a similar rate, just as observed
with citric acid. This only solidifies the findings of Thomas
Benson [42, 43] suggesting the concomitant nature of the
Li and Mg. Also, for Ca, more than 60% was extracted in 4
hours, with a slight increase as time increased from 4 hours
to 24 hours, leading to a maximum of about 70% for Ca.
Fe and Al followed a similar trend with a maximum extrac-
tion of around 58%.
Between tartaric acid and sulfuric acid, it can be seen
that tartaric acid has a lower leaching efficiency for Li, and
the selectivity for Li to other elements is low. It could be
suggested that this tendency is a result of the complex ions
formed between tartaric acid and the elements of interest,
permitting the considerable dissolution of all of them with-
out any selectivity. Sulfuric acid has a lower Ca extraction,
making it a selective reagent compared to tartaric acid.
Oxalic Acid
Oxalic acid, also known as ethanedioic acid, can be gen-
erated either through biological or commercial means,
with fungi, including white rots, brown rots, mycorrhizae,
plant pathogens, and Aspergillus niger (A.niger), being
the primary source. In the biological method, glucose is
transformed into oxalic and acetic acids through fungal
metabolism at pH values of 4.5–5, while in the commercial
method, oxaloacetate undergoes hydrolysis to yield oxalic
and acetic acids. It’s important to note that the solubility of
oxalic acid in water is 143 g L−1 [35].
Oxalic acid leaching was conducted under the same
conditions as the other acids, paying attention to the 5
main elements of interest, as depicted in Figure 7. Li had
a considerable extraction of about 90% in 1 hour, and
after 4 hours, there was no significant change in the extrac-
tions. Following Li was Al which consistently increased as
0
20
40
60
80
100
0 4 8 12 16 20 24 28
Time, hour
Citric Acid
Al
Ca
Fe
Li
Mg
Figure 5. Dissolution rates of main elements in claystone using citric acid. 1M acid, 80
°C, 10 L/S
Extraction,
%