XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3373
time increased from 1h to 24 hours. In the 1st hour, about
60% was extracted while in the 4th hour, almost 100%
was extracted. Fe also increased as time increased at the
same temperature of 80 °C, but the maximum extraction
did not exceed 65%. Mg extraction did not exceed 25%
which was an unusual observation because so far, Mg and
Li have always had similar trends and similar behaviors in
both physical and chemical processes, owing to the specula-
tion that both Li and Mg are concomitant. Also, Ca extrac-
tion was very low with a maximum extraction of 5.5% in
8 hours.
The ability of oxalic acid to selectively extract Li is of
great advantage to the subsequent downstream processes.
The low Mg and Ca dissolution with oxalic acid leaching
can be explained by the ineffective coordination of the car-
boxyl groups in oxalic acid (-COOH) with alkaline earth
metals. Except for Beryllium, alkaline earth metals would
generally form more oxalate compounds than oxalate com-
plexes [44, 45].
A comparison of the dissolution rates between oxalic
acid and sulfuric acid shows that oxalic acid is more selec-
tive for Li extraction from li-bearing claystone. The findings
reveal distinct dissolution behaviors among the 5 elements
0
20
40
60
80
100
0 4 8 12 16 20 24 28
Time, hour
Tartaric Acid
Al
Ca
Fe
Li
Mg
Figure 6. Dissolution rates of main elements in claystone using tartaric acid. 1M acid,
80 °C, 10 L/S
0
20
40
60
80
100
0 4 8 12 16 20 24 28
Time, hour
Oxalic Acid
Al
Ca
Fe
Li
Mg
Figure 7. Dissolution rates of main elements in claystone using oxalic acid. 1M acid, 80
°C, 10 L/S
Extraction,
%
Extraction,
%
time increased from 1h to 24 hours. In the 1st hour, about
60% was extracted while in the 4th hour, almost 100%
was extracted. Fe also increased as time increased at the
same temperature of 80 °C, but the maximum extraction
did not exceed 65%. Mg extraction did not exceed 25%
which was an unusual observation because so far, Mg and
Li have always had similar trends and similar behaviors in
both physical and chemical processes, owing to the specula-
tion that both Li and Mg are concomitant. Also, Ca extrac-
tion was very low with a maximum extraction of 5.5% in
8 hours.
The ability of oxalic acid to selectively extract Li is of
great advantage to the subsequent downstream processes.
The low Mg and Ca dissolution with oxalic acid leaching
can be explained by the ineffective coordination of the car-
boxyl groups in oxalic acid (-COOH) with alkaline earth
metals. Except for Beryllium, alkaline earth metals would
generally form more oxalate compounds than oxalate com-
plexes [44, 45].
A comparison of the dissolution rates between oxalic
acid and sulfuric acid shows that oxalic acid is more selec-
tive for Li extraction from li-bearing claystone. The findings
reveal distinct dissolution behaviors among the 5 elements
0
20
40
60
80
100
0 4 8 12 16 20 24 28
Time, hour
Tartaric Acid
Al
Ca
Fe
Li
Mg
Figure 6. Dissolution rates of main elements in claystone using tartaric acid. 1M acid,
80 °C, 10 L/S
0
20
40
60
80
100
0 4 8 12 16 20 24 28
Time, hour
Oxalic Acid
Al
Ca
Fe
Li
Mg
Figure 7. Dissolution rates of main elements in claystone using oxalic acid. 1M acid, 80
°C, 10 L/S
Extraction,
%
Extraction,
%