2589
An Investigation of Approaches for Enhanced Reverse Flotation
of Refractory Hematite Ore
Zhongxian Wu
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, Shandong, China
Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering
and Technology, China University of Mining and Technology, Xuzhou, Jiangsu, China
Dongping Tao
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, Shandong, China
Youjun Tao
Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering
and Technology, China University of Mining and Technology, Xuzhou, Jiangsu, China
Shuyong Liu
Donganshan Sintering Plant, Ansteel Group Corporation, Anshan, Liaoning, China
ABSTRACT: A systematic process mineralogy study was conducted to explore the fundamental reasons for
difficulties in refractory hematite flotation. The results show that hematite had fine particle size distributed over
0~45 µm with a liberation degree of 90.19%. The particle size of quartz was mainly distributed in 20~150 µm
with a liberation degree of only 67.72%. Unliberated quartz was mainly associated with hematite. The main
reasons for poor performance were the serious entrainment of fine hematite particles and the difficulty in
effective collection of coarse low-grade composite particles. Possible approaches for improving hematite flotation
performance have been proposed.
Keywords: Process mineralogy Hematite Quartz Reverse flotation Flotation mechanisms
INTRODUCTION
Hematite is a typical iron oxide ore used as a major raw
material for the iron and steel industry. As the continuous
exploitation of hematite resources, the reserves of rich ore
are getting fewer. In China, 55% of iron ore is known as
Anshan-style iron ore (Sun, 2006 Han et al., 2006). The
separation process of Chinese Anshan-type hematite ores
usually adopts a typical combined beneficiation process
including stage grinding, gravity separation, magnetic sep-
aration and flotation (Wu, 2013 Zhang et al., 2021). Its
main advantage is that the coarse liberated iron minerals
can be prior to separate from the gangue minerals by the
hydrocyclone after stage grinding (Zhang et al., 2021). The
coarse-grained grinding product is usually separated by a
combination process with spiral chute and low-intensity
magnetic separation (LIMS) to obtain the final concentrate
and tailings directly. And the fine-grained grinding product

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2589
An Investigation of Approaches for Enhanced Reverse Flotation
of Refractory Hematite Ore
Zhongxian Wu
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, Shandong, China
Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering
and Technology, China University of Mining and Technology, Xuzhou, Jiangsu, China
Dongping Tao
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, Shandong, China
Youjun Tao
Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering
and Technology, China University of Mining and Technology, Xuzhou, Jiangsu, China
Shuyong Liu
Donganshan Sintering Plant, Ansteel Group Corporation, Anshan, Liaoning, China
ABSTRACT: A systematic process mineralogy study was conducted to explore the fundamental reasons for
difficulties in refractory hematite flotation. The results show that hematite had fine particle size distributed over
0~45 µm with a liberation degree of 90.19%. The particle size of quartz was mainly distributed in 20~150 µm
with a liberation degree of only 67.72%. Unliberated quartz was mainly associated with hematite. The main
reasons for poor performance were the serious entrainment of fine hematite particles and the difficulty in
effective collection of coarse low-grade composite particles. Possible approaches for improving hematite flotation
performance have been proposed.
Keywords: Process mineralogy Hematite Quartz Reverse flotation Flotation mechanisms
INTRODUCTION
Hematite is a typical iron oxide ore used as a major raw
material for the iron and steel industry. As the continuous
exploitation of hematite resources, the reserves of rich ore
are getting fewer. In China, 55% of iron ore is known as
Anshan-style iron ore (Sun, 2006 Han et al., 2006). The
separation process of Chinese Anshan-type hematite ores
usually adopts a typical combined beneficiation process
including stage grinding, gravity separation, magnetic sep-
aration and flotation (Wu, 2013 Zhang et al., 2021). Its
main advantage is that the coarse liberated iron minerals
can be prior to separate from the gangue minerals by the
hydrocyclone after stage grinding (Zhang et al., 2021). The
coarse-grained grinding product is usually separated by a
combination process with spiral chute and low-intensity
magnetic separation (LIMS) to obtain the final concentrate
and tailings directly. And the fine-grained grinding product

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2590 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
is usually separated by a combination process with mag-
netic separation (i.e., LIMS and high-intensity magnetic
separation (HIMS)) and flotation. A partially qualified
concentrate can be obtained by LIMS, then its tailing is
used for HIMS to remove slimes, providing a better min-
eralogical feed with higher TFe grade for the subsequent
anionic reverse flotation process (Zhang et al., 2021).
The flotation feed in this study is a mixture of low
and high intensity magnetic concentrates for fine size frac-
tion from the typical combined beneficiation process of
iron ore. Jiang et al. (2019) characterized the particle size
of the flotation feed from a Qidashan concentrator with
similar process mineralogical properties to this study, and
their analysis showed that the flotation feed contained a
large number of fine particles with particle size of only a
few microns, or even less than one micron. For such fine
particles, flotation is considered to be one of the most
important separation techniques (Song and Lu, 1994), but
the flotation results obtained by conventional flotation are
always not satisfactory (Tao et al., 2021). Many scholars
have concentrated on developing flotation reagents to fur-
ther improve the flotation separation performance in recent
years. Luo et al. (2015) firstly applied the RA-315 anionic
collectors developed by Changsha Mining and Metallurgy
Research Institute in China to the Qishan beneficiation
plant (Anshan Steel Company, China) upgrading the TFe
grade of iron concentrate to 65.33% with an recovery of
80.72%. But the qualified concentrate (TFe grade 68.5%)
can be obtained by flotation process with one roughing,
one cleaning and two stages of scavenging. In summary,
the iron concentrate obtained by roughing flotation is
still poor, and the ideal flotation performance can only be
obtained by the complex closed-circuit process with several
cleaning flotation and scavenging flotation.
With the continuous updating of mineral analysis
equipments, the Mineral Liberation Analyzer (MLA) is
widely used to evaluate process mineralogy such as mineral
composition, particle size and liberation characteristics of
main minerals (Wu and Tao, 2021 Hoang et al., 2018).
In recent years, MLA has made some achievements in the
process mineralogical characterization of Chinese Anshan-
type iron ore. Jiang et al. (2019) investigated the process
mineralogy of the flotation feeds from Gongchangling and
Qidashan concentrator plant, respectively, and concluded
by the comparative analysis that the fine particle size of sid-
erite and its complex association with other iron minerals
are the main reasons for the difficult flotation of the flota-
tion feed in Gongchangling concentrator plant.
The purpose of this study using advanced MLA (min-
eral liberation analyzer) is to systematically investigate
the process mineralogy of the flotation feed samples from
Anqian concentration plant in China, and quantitatively
analyze the parameters such as mineral composition, min-
eral particle size and association relationship et al. The com-
bination of the screening analysis results of the roughing
flotation products with process mineralogy emphatically
analyzes the refractory mechanism of this sample and pro-
vides theoretical guidance for achieving efficient flotation
of iron ore.
MATERIALS AND METHODS
Minerals and Reagents
About 30 kg representative flotation feed sample was col-
lected from Anqian Processing Plant’s flotation shop of
Anshan Iron and Steel Co., Ltd., Anshan city, China. The
collected sample was mixed and homogenized thoroughly,
fractionated immediately for later measurements. The
beneficiation process of the Anqian concentrator plant is
shown in Figure 1.
As can be seen in Figure 1, the coarse liberated iron
minerals in the grinding product are removed by gravity
separation and magnetic separation. The fine particles after
hydrocyclone classification is mainly pre-enriched iron
minerals and removed non-magnetic coarse gangue min-
erals by magnetic separation, and the mixture of LIMS
concentrate and HIMS concentrate are defined as flotation
feeds. Therefore the particle size of flotation feed is fine and
contains plenty of slimes, as described in many papers on
Anshan-type iron ore beneficiation (Zhang et al., 2021
Jiang et al., 2019 Song and Lu, 1994 Tao et al., 2021).
Sodium hydroxide (NaOH) as pH regulator, corn
starch as hematite depressant, lime (CaO) as quartz activa-
tor, and anionic collector TD-II as quartz collector with an
industrial purity were acquired from the Anqian concentra-
tor plant of Anshan Iron and Steel Co., Ltd. Tap water with
pH 7.8 from Anshan was used in all experiments.
Methods
Sample Characterization
A 100 g homogenized sample was screened with standard
screens of 74 µm and 30 µm to obtain three-size fractions
for efficiency and accuracy of the test. And the yield of each
size fraction was determined. The three individual size frac-
tions were used to make sample pellets with epoxy resin
for mineral characterization using an MLA apparatus (FEI
MLA650F). Since the analytical principle of MLA deter-
mines mineral species through elemental composition, it
is difficult to distinguish minerals with little difference in
elemental content, such as magnetite and hematite, in the
MLA analysis of iron minerals.

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Extracted Text (may have errors)

2590 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
is usually separated by a combination process with mag-
netic separation (i.e., LIMS and high-intensity magnetic
separation (HIMS)) and flotation. A partially qualified
concentrate can be obtained by LIMS, then its tailing is
used for HIMS to remove slimes, providing a better min-
eralogical feed with higher TFe grade for the subsequent
anionic reverse flotation process (Zhang et al., 2021).
The flotation feed in this study is a mixture of low
and high intensity magnetic concentrates for fine size frac-
tion from the typical combined beneficiation process of
iron ore. Jiang et al. (2019) characterized the particle size
of the flotation feed from a Qidashan concentrator with
similar process mineralogical properties to this study, and
their analysis showed that the flotation feed contained a
large number of fine particles with particle size of only a
few microns, or even less than one micron. For such fine
particles, flotation is considered to be one of the most
important separation techniques (Song and Lu, 1994), but
the flotation results obtained by conventional flotation are
always not satisfactory (Tao et al., 2021). Many scholars
have concentrated on developing flotation reagents to fur-
ther improve the flotation separation performance in recent
years. Luo et al. (2015) firstly applied the RA-315 anionic
collectors developed by Changsha Mining and Metallurgy
Research Institute in China to the Qishan beneficiation
plant (Anshan Steel Company, China) upgrading the TFe
grade of iron concentrate to 65.33% with an recovery of
80.72%. But the qualified concentrate (TFe grade 68.5%)
can be obtained by flotation process with one roughing,
one cleaning and two stages of scavenging. In summary,
the iron concentrate obtained by roughing flotation is
still poor, and the ideal flotation performance can only be
obtained by the complex closed-circuit process with several
cleaning flotation and scavenging flotation.
With the continuous updating of mineral analysis
equipments, the Mineral Liberation Analyzer (MLA) is
widely used to evaluate process mineralogy such as mineral
composition, particle size and liberation characteristics of
main minerals (Wu and Tao, 2021 Hoang et al., 2018).
In recent years, MLA has made some achievements in the
process mineralogical characterization of Chinese Anshan-
type iron ore. Jiang et al. (2019) investigated the process
mineralogy of the flotation feeds from Gongchangling and
Qidashan concentrator plant, respectively, and concluded
by the comparative analysis that the fine particle size of sid-
erite and its complex association with other iron minerals
are the main reasons for the difficult flotation of the flota-
tion feed in Gongchangling concentrator plant.
The purpose of this study using advanced MLA (min-
eral liberation analyzer) is to systematically investigate
the process mineralogy of the flotation feed samples from
Anqian concentration plant in China, and quantitatively
analyze the parameters such as mineral composition, min-
eral particle size and association relationship et al. The com-
bination of the screening analysis results of the roughing
flotation products with process mineralogy emphatically
analyzes the refractory mechanism of this sample and pro-
vides theoretical guidance for achieving efficient flotation
of iron ore.
MATERIALS AND METHODS
Minerals and Reagents
About 30 kg representative flotation feed sample was col-
lected from Anqian Processing Plant’s flotation shop of
Anshan Iron and Steel Co., Ltd., Anshan city, China. The
collected sample was mixed and homogenized thoroughly,
fractionated immediately for later measurements. The
beneficiation process of the Anqian concentrator plant is
shown in Figure 1.
As can be seen in Figure 1, the coarse liberated iron
minerals in the grinding product are removed by gravity
separation and magnetic separation. The fine particles after
hydrocyclone classification is mainly pre-enriched iron
minerals and removed non-magnetic coarse gangue min-
erals by magnetic separation, and the mixture of LIMS
concentrate and HIMS concentrate are defined as flotation
feeds. Therefore the particle size of flotation feed is fine and
contains plenty of slimes, as described in many papers on
Anshan-type iron ore beneficiation (Zhang et al., 2021
Jiang et al., 2019 Song and Lu, 1994 Tao et al., 2021).
Sodium hydroxide (NaOH) as pH regulator, corn
starch as hematite depressant, lime (CaO) as quartz activa-
tor, and anionic collector TD-II as quartz collector with an
industrial purity were acquired from the Anqian concentra-
tor plant of Anshan Iron and Steel Co., Ltd. Tap water with
pH 7.8 from Anshan was used in all experiments.
Methods
Sample Characterization
A 100 g homogenized sample was screened with standard
screens of 74 µm and 30 µm to obtain three-size fractions
for efficiency and accuracy of the test. And the yield of each
size fraction was determined. The three individual size frac-
tions were used to make sample pellets with epoxy resin
for mineral characterization using an MLA apparatus (FEI
MLA650F). Since the analytical principle of MLA deter-
mines mineral species through elemental composition, it
is difficult to distinguish minerals with little difference in
elemental content, such as magnetite and hematite, in the
MLA analysis of iron minerals.

2588 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Yu, J., Ge, Y., Guo, X., Guo, W., The depression effect and
mechanism of NSFC on dolomite in the flotation of
phosphate ore. Separation and Purification Technology,
2016a, 161, 88–95.
Yu, J., Ge, Y., Hou, J., Behavior and mechanism of collo-
phane and dolomite separation using alkyl hydroxamic
acid as a flotation collector. Physicochemical Problems
of Mineral Processing, 2016b, 52(1), 155–169.
Zou, H., Cao, Q.-b., Liu, D.-w., Chen, X.-m., Jiao, Y.,
Flotation features of fluorapatite with ricinoleic
acid: the role of hydrogen bonds between collectors.
Chemical Papers, 2021, 75, 1949–1958.

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Extracted Text (may have errors)