XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2677
Carbon Proximate Analysis
Fixed carbon (FC) and ash content in ASR-char were
analyzed using the “carbon proximate analysis method”
based on ISO 17246:2005. The carbon proximate analysis
consists of three main steps: drying, devolatilization, and
combustion. The sample was dried at 110±5°C for 3 hours
in an open crucible for moisture content (MC) measure-
ment. Then, the dried sample was heated at 900±10°C
for 7 minutes inside a closed crucible to remove volatile
matter (VM). Lastly, the sample was burned at 810±5°C
for 3 hours in an open crucible to produce ash. The mass
of the sample and the crucible at every step was measured
using analytical balance. The mass of fixed carbon (FC) was
then calculated by subtracting the mass of moisture (MC),
volatile matter (VM), and ash from the original mass of the
ASR-char sample (m0), as shown in Eq. 5.
MC VM Ash FC m0 =---(5)
Elemental Composition Analysis
The ASR-char’s elemental composition was identified
by analyzing the ASR-char using an X-Ray Fluorescence
Spectrophotometer (XRF: RIGAKU Supermini 200).
Froth Flotation Experiment
Three different size fractions, namely SR-Sieve, SR-Cyclone,
and SR-Wind, were treated by froth flotation. The froth flo-
tation experiment was conducted in a 250 mL rectangular
flotation cell equipped with a propeller and a nozzle to sup-
ply air. The rotational speed of the agitator was set to 1,500
rpm while the air velocity was adjusted to the level so that
medium-sized bubbles would eventually form. Dodecyl
ammonium acetate (DAA) was added (dosage: 5.0 × 10–4
kg-DAA/kg-sample) as a surfactant to recover carbon in the
concentrate after adjusting the pH of the aqueous solution
to 5.5. At the same time, methyl isobutyl carbinol (MIBC)
was used as a frother due to its good frothing action in fine
coal flotation (dosage: 5.0 × 10–4 L-MIBC/kg-sample). The
pulp density was kept constant at 10 wt.%. The flotation
was performed for 1, 2, 3, or 5 minutes before the separated
fractions were collected and analyzed for carbon or were
subject to XRF analysis to quantify the grade of carbon in
the product. After obtaining the data from the flotation
experiment, the recovery and grade of carbon in the con-
centrate were calculated using the modified first-order rate
equation (Eq. 1) and the new kinetic model (Eq. 4) after
a programming code was first prepared in the MATLAB
environment.
RESULTS AND DISCUSSIONS
Characterization of ASR-char
Before the flotation experiments, the samples were subject
to several analyses, namely, particle size distribution mea-
surement, carbon proximate analysis, and XRF analysis, to
analyze the elemental composition of the samples. Figure 2
shows the particle size distribution of the ASR-char sample.
Although the average size of the ASR-char sample is rela-
tively small (i.e., D50 =33.01 µm), the size distribution is
not homogeneous (since D90 =523.7 µm is relatively large).
In addition, the results of the particle size analysis of
these three size fractions showed that the SR-Sieve has the
largest particle size, whereas the SR-Wind was the smallest
(Figure 3, Table 1).
Table 1. Results of particle size analysis of three different size
fractions
Particle Size
Size Fraction
SR-Sieve SR-Cyclone SR-Wind
D
10 ,(μm) 66.5 36.1 13.3
D50, (μm) 409.0 104.7 33.7
D90, (μm) 915.7 301.2 59.6
The carbon proximate analysis showed that the compo-
sition of ASR-char included volatile matter (18.2%), fixed
carbon (26.2%), and ash (55.6%). Table 2 shows the total
composition of ASR-char (dry basis). It was also found that
the main components of ASR-char besides carbon and vol-
atile matter are mainly CaCO3 (19.3%), Fe3O4 (10.4%),
SiO2 (6.8%), ZnO (5.5%), and Cl (4.4%). Table 3, on
the other hand, shows the results of the XRF analysis per-
formed on the three different size fractions. The fraction
with the lowest D50 value (i.e., SR-Wind) was found to
have the highest carbon content (i.e., 37.3%).
Considering the results of the qualitative and quantita-
tive analysis (Tables 2 and 3), it is important to note that
without treatment, using ASR-char as a solid fuel is not a
feasible option due to the relatively large content of impu-
rities, such as CaCO3, Fe3O4, SiO2, and Cl. The chlorine
content must be removed before using the char because it
might cause corrosion, etc. The chlorine can be removed
by washing with water and CO2 bubbling (Dodbiba et
al., 2021). On the other hand, the carbonaceous compo-
nent can be recovered by employing froth flotation, which
can collect carbon in the concentrate while other minerals
remain in the tailing (Laskowski, 2001).
Carbon Proximate Analysis
Fixed carbon (FC) and ash content in ASR-char were
analyzed using the “carbon proximate analysis method”
based on ISO 17246:2005. The carbon proximate analysis
consists of three main steps: drying, devolatilization, and
combustion. The sample was dried at 110±5°C for 3 hours
in an open crucible for moisture content (MC) measure-
ment. Then, the dried sample was heated at 900±10°C
for 7 minutes inside a closed crucible to remove volatile
matter (VM). Lastly, the sample was burned at 810±5°C
for 3 hours in an open crucible to produce ash. The mass
of the sample and the crucible at every step was measured
using analytical balance. The mass of fixed carbon (FC) was
then calculated by subtracting the mass of moisture (MC),
volatile matter (VM), and ash from the original mass of the
ASR-char sample (m0), as shown in Eq. 5.
MC VM Ash FC m0 =---(5)
Elemental Composition Analysis
The ASR-char’s elemental composition was identified
by analyzing the ASR-char using an X-Ray Fluorescence
Spectrophotometer (XRF: RIGAKU Supermini 200).
Froth Flotation Experiment
Three different size fractions, namely SR-Sieve, SR-Cyclone,
and SR-Wind, were treated by froth flotation. The froth flo-
tation experiment was conducted in a 250 mL rectangular
flotation cell equipped with a propeller and a nozzle to sup-
ply air. The rotational speed of the agitator was set to 1,500
rpm while the air velocity was adjusted to the level so that
medium-sized bubbles would eventually form. Dodecyl
ammonium acetate (DAA) was added (dosage: 5.0 × 10–4
kg-DAA/kg-sample) as a surfactant to recover carbon in the
concentrate after adjusting the pH of the aqueous solution
to 5.5. At the same time, methyl isobutyl carbinol (MIBC)
was used as a frother due to its good frothing action in fine
coal flotation (dosage: 5.0 × 10–4 L-MIBC/kg-sample). The
pulp density was kept constant at 10 wt.%. The flotation
was performed for 1, 2, 3, or 5 minutes before the separated
fractions were collected and analyzed for carbon or were
subject to XRF analysis to quantify the grade of carbon in
the product. After obtaining the data from the flotation
experiment, the recovery and grade of carbon in the con-
centrate were calculated using the modified first-order rate
equation (Eq. 1) and the new kinetic model (Eq. 4) after
a programming code was first prepared in the MATLAB
environment.
RESULTS AND DISCUSSIONS
Characterization of ASR-char
Before the flotation experiments, the samples were subject
to several analyses, namely, particle size distribution mea-
surement, carbon proximate analysis, and XRF analysis, to
analyze the elemental composition of the samples. Figure 2
shows the particle size distribution of the ASR-char sample.
Although the average size of the ASR-char sample is rela-
tively small (i.e., D50 =33.01 µm), the size distribution is
not homogeneous (since D90 =523.7 µm is relatively large).
In addition, the results of the particle size analysis of
these three size fractions showed that the SR-Sieve has the
largest particle size, whereas the SR-Wind was the smallest
(Figure 3, Table 1).
Table 1. Results of particle size analysis of three different size
fractions
Particle Size
Size Fraction
SR-Sieve SR-Cyclone SR-Wind
D
10 ,(μm) 66.5 36.1 13.3
D50, (μm) 409.0 104.7 33.7
D90, (μm) 915.7 301.2 59.6
The carbon proximate analysis showed that the compo-
sition of ASR-char included volatile matter (18.2%), fixed
carbon (26.2%), and ash (55.6%). Table 2 shows the total
composition of ASR-char (dry basis). It was also found that
the main components of ASR-char besides carbon and vol-
atile matter are mainly CaCO3 (19.3%), Fe3O4 (10.4%),
SiO2 (6.8%), ZnO (5.5%), and Cl (4.4%). Table 3, on
the other hand, shows the results of the XRF analysis per-
formed on the three different size fractions. The fraction
with the lowest D50 value (i.e., SR-Wind) was found to
have the highest carbon content (i.e., 37.3%).
Considering the results of the qualitative and quantita-
tive analysis (Tables 2 and 3), it is important to note that
without treatment, using ASR-char as a solid fuel is not a
feasible option due to the relatively large content of impu-
rities, such as CaCO3, Fe3O4, SiO2, and Cl. The chlorine
content must be removed before using the char because it
might cause corrosion, etc. The chlorine can be removed
by washing with water and CO2 bubbling (Dodbiba et
al., 2021). On the other hand, the carbonaceous compo-
nent can be recovered by employing froth flotation, which
can collect carbon in the concentrate while other minerals
remain in the tailing (Laskowski, 2001).