520 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
RESULTS AND DISCUSSION
Characterization Studies
The chemical analysis of the slag found that the CaO
content is reported at 44.42%, a significant component.
The iron content of the slag is 17.48%, with FeO/Wustite
found to be 11.4%. The phosphorous content is found to
be at a significant level and reported to be 2.83% P2O5.
Free lime is found to be 2.4% Caf, and there is no metallic
iron present in the sample.
Particle size analysis was carried out for the as-received
slag and envisaged that 80% of the particles are 3.4 mm
with a top size of 10 mm (5.3% of +6 mm) in the BOF
slag. Also, 50% of the particles are 0.67 mm, with 16.8%
of the sample being 0.106 mm. Further, the size-wise
chemical analysis was carried out for the as-received slag,
and the results are shown in Figure 2. It is observed that
the maximum CaO value is reported at finer size fractions,
i.e., below 0.25 mm. Similarly maximum iron content is
at coarser size fractions and the maximum value of 23.4%
–3+1 mm size fraction.
The apparent and bulk density are the critical param-
eters of the material, which is measured for the BOF slag
sample by using a Pycnometer. The true density of the BOF
slag sample is found to be 3.28 g/cc, whereas a 2.13 g/cc
value was reported for the bulk density. The average poros-
ity of the as-received sample is found to be 35.3%.
The results of the sink and float studies for the slag
(grounded to 3 mm) are shown in Figure 3. From the
results, it is clear that sink fraction can be enriched to 20.2%
Fe(T) with a yield of 43.8%. Further, the CaO content is
upgraded to 46.7% CaO (in float product) with a yield of
45.4%. Similarly, iron content in the float can be lowered to
below 12.2% Fe(T). There is an insignificant change in the
phosphorous content of the products. Furthermore, it can
be studied by lowering the particle size for better liberation.
XRD pattern for the slag sample is carried out and
the result is depicted in Figure 4. From the Figure 4, it is
found that slag sample contains spinel of Brownmillerite
(Al0.55Ca2Fe1.45O5),Wuestite(FeO),Hatrurite(Ca3O5Si1),
Brownmillerite (Mg, Si-exchanged) (Al0.665Ca2Fe1.052Mg0
.133 O5Si0.133), Dicalcium Silicate -Alpha (Ca2O4Si1) and
Dicalcium Diiron(III) Oxide (Ca2Fe2O5). However, metal-
lic iron and free lime were not reported in the sample due
to the presence of lower content of the detection level of
the system.
Electron-probe micro-analysis of the different grains/
particles in the slag sample was carried out by using SEM-
EDS. Images with few particles are depicted, and the analy-
sis is shown in Figure 5. From Figure 5, it is found that
BOF slag is very complicated in the system, with different
phases interlocking with each other. Also, it is found that
there is free, liberated metal grain in the form of a droplet
at particle size below 75µm. It is also indicated that there
is a distinct phase difference between calcium-rich silicates
and iron-rich oxide phases. Also, magnesium is found to
be interlocked with iron-rich particles, and phosphorous
is well-locked with calcium-silicate particles. It is also evi-
dent that most of the iron is present in the oxide phase,
with iron content varying from 55 to 90% Fe. The particles
with iron content higher than 50% can be separated using
magnetic separation and recycled in an iron-steel-making
Figure 2. Size-wise assay value of BOF slag
RESULTS AND DISCUSSION
Characterization Studies
The chemical analysis of the slag found that the CaO
content is reported at 44.42%, a significant component.
The iron content of the slag is 17.48%, with FeO/Wustite
found to be 11.4%. The phosphorous content is found to
be at a significant level and reported to be 2.83% P2O5.
Free lime is found to be 2.4% Caf, and there is no metallic
iron present in the sample.
Particle size analysis was carried out for the as-received
slag and envisaged that 80% of the particles are 3.4 mm
with a top size of 10 mm (5.3% of +6 mm) in the BOF
slag. Also, 50% of the particles are 0.67 mm, with 16.8%
of the sample being 0.106 mm. Further, the size-wise
chemical analysis was carried out for the as-received slag,
and the results are shown in Figure 2. It is observed that
the maximum CaO value is reported at finer size fractions,
i.e., below 0.25 mm. Similarly maximum iron content is
at coarser size fractions and the maximum value of 23.4%
–3+1 mm size fraction.
The apparent and bulk density are the critical param-
eters of the material, which is measured for the BOF slag
sample by using a Pycnometer. The true density of the BOF
slag sample is found to be 3.28 g/cc, whereas a 2.13 g/cc
value was reported for the bulk density. The average poros-
ity of the as-received sample is found to be 35.3%.
The results of the sink and float studies for the slag
(grounded to 3 mm) are shown in Figure 3. From the
results, it is clear that sink fraction can be enriched to 20.2%
Fe(T) with a yield of 43.8%. Further, the CaO content is
upgraded to 46.7% CaO (in float product) with a yield of
45.4%. Similarly, iron content in the float can be lowered to
below 12.2% Fe(T). There is an insignificant change in the
phosphorous content of the products. Furthermore, it can
be studied by lowering the particle size for better liberation.
XRD pattern for the slag sample is carried out and
the result is depicted in Figure 4. From the Figure 4, it is
found that slag sample contains spinel of Brownmillerite
(Al0.55Ca2Fe1.45O5),Wuestite(FeO),Hatrurite(Ca3O5Si1),
Brownmillerite (Mg, Si-exchanged) (Al0.665Ca2Fe1.052Mg0
.133 O5Si0.133), Dicalcium Silicate -Alpha (Ca2O4Si1) and
Dicalcium Diiron(III) Oxide (Ca2Fe2O5). However, metal-
lic iron and free lime were not reported in the sample due
to the presence of lower content of the detection level of
the system.
Electron-probe micro-analysis of the different grains/
particles in the slag sample was carried out by using SEM-
EDS. Images with few particles are depicted, and the analy-
sis is shown in Figure 5. From Figure 5, it is found that
BOF slag is very complicated in the system, with different
phases interlocking with each other. Also, it is found that
there is free, liberated metal grain in the form of a droplet
at particle size below 75µm. It is also indicated that there
is a distinct phase difference between calcium-rich silicates
and iron-rich oxide phases. Also, magnesium is found to
be interlocked with iron-rich particles, and phosphorous
is well-locked with calcium-silicate particles. It is also evi-
dent that most of the iron is present in the oxide phase,
with iron content varying from 55 to 90% Fe. The particles
with iron content higher than 50% can be separated using
magnetic separation and recycled in an iron-steel-making
Figure 2. Size-wise assay value of BOF slag