176 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
fit the DoE requirements by dilution using deionized water.
After acid leaching, the flask was cooled down for 10 min-
utes in an ice bath, and the content filtered on a Büchner
funnel fitted with a paper filter (Whatman Filter paper
41 ashless, diameter 41 mm). The solid was washed three
times with 10 mL deionized water. The leachate residues
were then set to dry in an oven at 105°C. Leachates and
washing waters were collected in plastic tubes and stored in
the fridge pending analysis. Only the experimental condi-
tion yielding the best results were done in triplicates, as the
amount of biomass available was limited.
Aluminum sulphate crystallization was performed
using a Heidolph Laborota 4002 -Control rotary evapora-
tor at 60°C under vacuum in a round bottom flask until all
solvent was evaporated. Residue remaining in the flask after
evaporation was dried at 105°C in an oven.
RESULTS AND DISCUSSION
Sample Characterization
Biomass TGA Results
Figure 1 shows the results of TGA performed on raw bio-
mass. Three main losses of mass were identified, following a
scheme typical of biomass combustion under air.
The first one (between 30 and 150°C) was attributed
to water evaporation. The second and third ones (between
250 and 500°C) were assigned to the combustion of organic
matter. A fourth mass loss, occurring at around 550°C and
accounting for 0.122% of the sample total mass could be
identified on the figure. It could be attributed to carbonate
oxidation. These results indicate that complete combustion
of the organic matter was reached at around 550–600°C,
but the maximal mass loss was attained at around 750°C.
The combustion temperature chosen to produce the ash
was 900°C, in order to maximize the concentration of the
bio-ore. The ash produced at this temperature was a white
powder of very low density and high volatility (Figure 2).
Elemental Characterization of Ash and Biomass
In Table 2 are presented the results of the CHONSCl anal-
ysis of biomass and 900°C ash. Ash is very poor in carbon,
as expected, showing good degradation of the organic mat-
ter. The remaining carbon percentage can be attributed to
the presence of carbonates oxides.
Table 3 shows the ICP-OES analysis of the raw bio-
mass and 900°C ash. Biomass analysis confirms that Qualea
rosea is indeed an aluminum hyperaccumulator, as the alu-
minum concentration in dry biomass is well above the
1000 ppm threshold, at 3911 ppm. The ash produced at
900°C is very concentrated in aluminum, at around 27%
in mass. Other elements in significant amounts are calcium,
magnesium, potassium and sulfur.
XRD analysis of the ash presented in Figure 2 showed
its very crystalline nature, despite a relatively low silicon
content, and gave information on the aluminum specia-
tion in the ash. Its crystalline form is mainly a calcium and
aluminum oxide and no trace of mullite or other alumi-
num silicates was detected, in contrast with what is usually
Table 2. Major element analysis of Qualea rosea biomass and
ash at 900°C, results given in mass percentage
N C H S O Cl
Biomass 0.02 45.2 6.64 0.32 44.88 0.27
Ash 900°C 0 0.75 0.22 2.17 8.36 0.14
Table 3. Trace elements analysis of Qualea rosea biomass and
ash at 900°C
Element Biomass (ppm) Ash 900°C (ppm)
Mg 598 43444
Al 3911 269653
Fe 62 4698
Na 4818 17057
K 1081 29480
S 451 26923
Mn 19 1544
P 0 2480
Ca 2888 156638
Zn 0 513
Si 1581 17269
Figure 1. Thermogravimetric analysis of the raw Qualea
rosea biomass
fit the DoE requirements by dilution using deionized water.
After acid leaching, the flask was cooled down for 10 min-
utes in an ice bath, and the content filtered on a Büchner
funnel fitted with a paper filter (Whatman Filter paper
41 ashless, diameter 41 mm). The solid was washed three
times with 10 mL deionized water. The leachate residues
were then set to dry in an oven at 105°C. Leachates and
washing waters were collected in plastic tubes and stored in
the fridge pending analysis. Only the experimental condi-
tion yielding the best results were done in triplicates, as the
amount of biomass available was limited.
Aluminum sulphate crystallization was performed
using a Heidolph Laborota 4002 -Control rotary evapora-
tor at 60°C under vacuum in a round bottom flask until all
solvent was evaporated. Residue remaining in the flask after
evaporation was dried at 105°C in an oven.
RESULTS AND DISCUSSION
Sample Characterization
Biomass TGA Results
Figure 1 shows the results of TGA performed on raw bio-
mass. Three main losses of mass were identified, following a
scheme typical of biomass combustion under air.
The first one (between 30 and 150°C) was attributed
to water evaporation. The second and third ones (between
250 and 500°C) were assigned to the combustion of organic
matter. A fourth mass loss, occurring at around 550°C and
accounting for 0.122% of the sample total mass could be
identified on the figure. It could be attributed to carbonate
oxidation. These results indicate that complete combustion
of the organic matter was reached at around 550–600°C,
but the maximal mass loss was attained at around 750°C.
The combustion temperature chosen to produce the ash
was 900°C, in order to maximize the concentration of the
bio-ore. The ash produced at this temperature was a white
powder of very low density and high volatility (Figure 2).
Elemental Characterization of Ash and Biomass
In Table 2 are presented the results of the CHONSCl anal-
ysis of biomass and 900°C ash. Ash is very poor in carbon,
as expected, showing good degradation of the organic mat-
ter. The remaining carbon percentage can be attributed to
the presence of carbonates oxides.
Table 3 shows the ICP-OES analysis of the raw bio-
mass and 900°C ash. Biomass analysis confirms that Qualea
rosea is indeed an aluminum hyperaccumulator, as the alu-
minum concentration in dry biomass is well above the
1000 ppm threshold, at 3911 ppm. The ash produced at
900°C is very concentrated in aluminum, at around 27%
in mass. Other elements in significant amounts are calcium,
magnesium, potassium and sulfur.
XRD analysis of the ash presented in Figure 2 showed
its very crystalline nature, despite a relatively low silicon
content, and gave information on the aluminum specia-
tion in the ash. Its crystalline form is mainly a calcium and
aluminum oxide and no trace of mullite or other alumi-
num silicates was detected, in contrast with what is usually
Table 2. Major element analysis of Qualea rosea biomass and
ash at 900°C, results given in mass percentage
N C H S O Cl
Biomass 0.02 45.2 6.64 0.32 44.88 0.27
Ash 900°C 0 0.75 0.22 2.17 8.36 0.14
Table 3. Trace elements analysis of Qualea rosea biomass and
ash at 900°C
Element Biomass (ppm) Ash 900°C (ppm)
Mg 598 43444
Al 3911 269653
Fe 62 4698
Na 4818 17057
K 1081 29480
S 451 26923
Mn 19 1544
P 0 2480
Ca 2888 156638
Zn 0 513
Si 1581 17269
Figure 1. Thermogravimetric analysis of the raw Qualea
rosea biomass