1940 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
recycled back into the system through sintering or blending
in agglomeration[2][3]. Briquettes made up of BFD suffers
issue of strength when charged in blast furnace. Material
characteristics change when BFD is exposed to the atmo-
sphere for a prolonged time. The presence of fayalite and
wustite in BFD makes magnetic separation difficult. The
above complexity in utilization directs towards separating
carbonaceous material from ferruginous material.
Many researchers have attempted to utilise and recover
the beneficial components and remove the harmful sub-
stances of BFD using physical and thermal beneficiation
and hydrometallurgical methods.
The effectiveness of the flotation process relies on the
choice of the suitable type and dosage of surfactants. It is,
in turn, dependent on the information on the liberation
size and associated gangue impurities derived from the
mineralogical investigations. Flotation using diesel oil as
collectors has proven to be very effective for coal-based
minerals. Floatation techniques have been used extensively
to separate Iron and carbon owing to the hydrophobic
nature of carbon. Floatation is satisfactory if carbon is pres-
ent as an individual entity. However, the presence of carbon
in association with other phases, such as carbonates and
carbides, leads to poor floatation[4]. B. Das et al. studied
froth floatation using diesel oil and MIBC as frother and
collector, respectively, to remove carbon from BFD. Tailing
was subjected to LIMS for iron removal [5]. The surface
characteristics of the weathered carbonaceous substance are
less suitable for adequate floatation. Carbon in such mate-
rial is in oxidised form, which makes it quite challenging
to flotation and separate carbonaceous material from iron
phase minerals. Unless the surface is deoxidised, modifying
the surface to hydrophobic using a collector is not feasible.
The oxidised surface is treated with alcohol to make an ester
group by esterification in this way, the surface becomes
deoxidised. After deoxidation, by putting collector, the
surface becomes hydrophobic in nature and floatability
increases [6] [7]. Jena et al. studied the floatation character-
istics of oxidised coal based on the hydrophilicity index [8].
W. Xia et al. studied FTIR analysis of blank coal sample,
alcohol treated coal and floatation concentrate sample by
evaluating hydrophilicity index [9]. Similar research has
been carried out in oxidised coal involving FTIR charac-
terisation for enhancing the floatability of coal [10]
B. Das et al. reported that flotation tailings are rich in
ferruginous phases and can be recovered by magnetic sepa-
ration technique [5]. Research on a Fresh BFD under mag-
netic separation indicates that even hematite is separable
under WHIMS at a magnetic intensity of 1.3–1.5 Tesla.
The effectiveness of magnetic separation depends on the
magnetic susceptibility of the feed material. Xiong et al.
have indicated the magnetic susceptibility of iron ore-
related minerals wherein magnetite has magnetic sus-
ceptibility in the range of 625–1156, martite 6.2–13.5,
hematite 0.6–2.16 and limonite 0.3–1.0 (×10+6 m3/kg)
[13]. Magnetic susceptibility decreases as wustite becomes
a predominant phase. Magnetic separation is quite chal-
lenging since all the iron phase minerals are not magne-
tite. Another study shows that it is possible to recover coke
fines with more than 80% carbon with a 30% yield from
BFD column flotation techniques. The flotation tailings are
subjected to a low-intensity magnetic separation technique.
This process could obtain a product with 62–65% Fe at a
yield of ~30%. The overall product obtained was 64.1% Fe
grade with overall recoveries of 48–55% [11] .
Rath et al. studied the magnetic separation which
suggests that it is challenging to directly beneficiate the
BFD sample to a satisfactory level, either using low-inten-
sity magnetic separation (LIMS) or the combination of
both LIMS and wet high-intensity magnetic separation
(WHIMS)[12]. Tripathy et al. studied the effect of various
parameters like magnetic intensity, rpm, and feed rate on
magnetic separation performance. Iron content increases
monotonically with magnetic intensity. Iron content
decreases beyond a certain intensity due to the mechanical
entrapment of the fine silica particles in magnetic content
[14]. M. Dworzanowski et al. investigated the recovery of a
saleable iron ore product from the +45 μm fraction of the
flotation tailings that would require regrinding. Fine par-
ticle size means that selectivity in terms of magnetic suscep-
tibility is much greater for magnetite particles [15] .Y. Shao
et al. also reported that when particle size is larger than
23μm, WHIMS can effectively recover hematite. When the
size is less than 23μm, hematite has to be pre-treated by
flocculation or another process to improve the performance
of magnetic separation [16]. Shibaeva et al. analysed the
effect of dry magnetic separation on the process of ferrugi-
nous disintegration concerning mineral liberation during
crushing[17].
The aim of this work is to assess the blast furnace flue
dust utilisation with detailed characterisation and physi-
cal beneficiation trials. The floatation study was carried
out using different reagents for three different feed sizes.
The magnetic separation study consists of LIMS targeting
mainly magnetite material, and WHIMS was incorporated
to separate other ferruginous material from gangues and
remaining carbonaceous material. The feed size was opti-
mised based on particle liberation, and process parameters
were optimised based on yield, iron grade, iron recovery
recycled back into the system through sintering or blending
in agglomeration[2][3]. Briquettes made up of BFD suffers
issue of strength when charged in blast furnace. Material
characteristics change when BFD is exposed to the atmo-
sphere for a prolonged time. The presence of fayalite and
wustite in BFD makes magnetic separation difficult. The
above complexity in utilization directs towards separating
carbonaceous material from ferruginous material.
Many researchers have attempted to utilise and recover
the beneficial components and remove the harmful sub-
stances of BFD using physical and thermal beneficiation
and hydrometallurgical methods.
The effectiveness of the flotation process relies on the
choice of the suitable type and dosage of surfactants. It is,
in turn, dependent on the information on the liberation
size and associated gangue impurities derived from the
mineralogical investigations. Flotation using diesel oil as
collectors has proven to be very effective for coal-based
minerals. Floatation techniques have been used extensively
to separate Iron and carbon owing to the hydrophobic
nature of carbon. Floatation is satisfactory if carbon is pres-
ent as an individual entity. However, the presence of carbon
in association with other phases, such as carbonates and
carbides, leads to poor floatation[4]. B. Das et al. studied
froth floatation using diesel oil and MIBC as frother and
collector, respectively, to remove carbon from BFD. Tailing
was subjected to LIMS for iron removal [5]. The surface
characteristics of the weathered carbonaceous substance are
less suitable for adequate floatation. Carbon in such mate-
rial is in oxidised form, which makes it quite challenging
to flotation and separate carbonaceous material from iron
phase minerals. Unless the surface is deoxidised, modifying
the surface to hydrophobic using a collector is not feasible.
The oxidised surface is treated with alcohol to make an ester
group by esterification in this way, the surface becomes
deoxidised. After deoxidation, by putting collector, the
surface becomes hydrophobic in nature and floatability
increases [6] [7]. Jena et al. studied the floatation character-
istics of oxidised coal based on the hydrophilicity index [8].
W. Xia et al. studied FTIR analysis of blank coal sample,
alcohol treated coal and floatation concentrate sample by
evaluating hydrophilicity index [9]. Similar research has
been carried out in oxidised coal involving FTIR charac-
terisation for enhancing the floatability of coal [10]
B. Das et al. reported that flotation tailings are rich in
ferruginous phases and can be recovered by magnetic sepa-
ration technique [5]. Research on a Fresh BFD under mag-
netic separation indicates that even hematite is separable
under WHIMS at a magnetic intensity of 1.3–1.5 Tesla.
The effectiveness of magnetic separation depends on the
magnetic susceptibility of the feed material. Xiong et al.
have indicated the magnetic susceptibility of iron ore-
related minerals wherein magnetite has magnetic sus-
ceptibility in the range of 625–1156, martite 6.2–13.5,
hematite 0.6–2.16 and limonite 0.3–1.0 (×10+6 m3/kg)
[13]. Magnetic susceptibility decreases as wustite becomes
a predominant phase. Magnetic separation is quite chal-
lenging since all the iron phase minerals are not magne-
tite. Another study shows that it is possible to recover coke
fines with more than 80% carbon with a 30% yield from
BFD column flotation techniques. The flotation tailings are
subjected to a low-intensity magnetic separation technique.
This process could obtain a product with 62–65% Fe at a
yield of ~30%. The overall product obtained was 64.1% Fe
grade with overall recoveries of 48–55% [11] .
Rath et al. studied the magnetic separation which
suggests that it is challenging to directly beneficiate the
BFD sample to a satisfactory level, either using low-inten-
sity magnetic separation (LIMS) or the combination of
both LIMS and wet high-intensity magnetic separation
(WHIMS)[12]. Tripathy et al. studied the effect of various
parameters like magnetic intensity, rpm, and feed rate on
magnetic separation performance. Iron content increases
monotonically with magnetic intensity. Iron content
decreases beyond a certain intensity due to the mechanical
entrapment of the fine silica particles in magnetic content
[14]. M. Dworzanowski et al. investigated the recovery of a
saleable iron ore product from the +45 μm fraction of the
flotation tailings that would require regrinding. Fine par-
ticle size means that selectivity in terms of magnetic suscep-
tibility is much greater for magnetite particles [15] .Y. Shao
et al. also reported that when particle size is larger than
23μm, WHIMS can effectively recover hematite. When the
size is less than 23μm, hematite has to be pre-treated by
flocculation or another process to improve the performance
of magnetic separation [16]. Shibaeva et al. analysed the
effect of dry magnetic separation on the process of ferrugi-
nous disintegration concerning mineral liberation during
crushing[17].
The aim of this work is to assess the blast furnace flue
dust utilisation with detailed characterisation and physi-
cal beneficiation trials. The floatation study was carried
out using different reagents for three different feed sizes.
The magnetic separation study consists of LIMS targeting
mainly magnetite material, and WHIMS was incorporated
to separate other ferruginous material from gangues and
remaining carbonaceous material. The feed size was opti-
mised based on particle liberation, and process parameters
were optimised based on yield, iron grade, iron recovery