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Enhancing Ultrafine Iron Ore Particle Recovery with
Extended Height Magnetic Matrices
Fernanda Hoffmann, José Ribeiro
Gaustec Magnetismo
Claudio Ribeiro
Gaustec America LLC
ABSTRACT: This study focuses on enhancing the recovery of ultrafine iron ore particles, typically measuring
below 45µm, to mitigate their disposal in tailings dams. Efficient recovery of these small particles necessitates
extended exposure to a magnetic field. Experimental trials were conducted using matrices of different heights,
ranging from 220 mm to 880 mm. Findings highlight that a matrix height of 440 mm offers the most cost-
effective solution, yielding 2.5 times increase in mass recovery while improving the concentrate grades, when
compared to the standard 220 mm matrices. Notably, these matrices can be seamlessly retrofitted into existing
magnetic separators with minimal modifications.
INTRODUCTION
Ultrafine particles, smaller than 45µm, have been a chal-
lenge in the mineral processing sector for several decades.
Particularly in iron mining, these particles are removed
from the beneficiation circuit and deposited directly into
tailings dams along with the ore processing rejects because
existing concentration methods are inefficient for these par-
ticle sizes (Gonçalves 2023). In other words, these particles
do not undergo any concentration stage, even though they
may contain recoverable iron content.
However, this method of discarding ultrafine particles
has been under review for some years. Due to the challenges
of environmental licensing, companies have been striving
to minimize the amount of material dumped into tailings
dams. Consequently, mining companies have increasingly
sought innovations with the aim of reducing waste genera-
tion (Silva et al., 2023).
Ultrafine particles are typically generated in the grind-
ing stage, as it is necessary at this stage to reduce the ore to
very fine granulometries to achieve the necessary liberation
degree between iron ore and quartz (silica) (Figueira, Luz
and Almeida 2010), enabling iron concentration.
It is important to highlight that these ultrafine parti-
cles, currently discarded because they are not fully recover-
able by current methods, typically have granulometry and
liberation degree suitable for pellet feed production, below
0.150mm (PUC-RJ). Concentrating these particles repre-
sents a significant opportunity to improve the utilization of
mineral resources in a project.
One of the most traditional methods for recover-
ing iron ore is high-intensity magnetic separation. In this
methodology, the exposure time of particles to the mag-
netic field directly influences their recovery, especially for
very fine granulometries.
Therefore, one feasible proposal to increase the recov-
ery of these materials is to extend the exposure time of par-
ticles by increasing the height of the magnetic matrices, the
element where magnetic concentration occurs.
Enhancing Ultrafine Iron Ore Particle Recovery with
Extended Height Magnetic Matrices
Fernanda Hoffmann, José Ribeiro
Gaustec Magnetismo
Claudio Ribeiro
Gaustec America LLC
ABSTRACT: This study focuses on enhancing the recovery of ultrafine iron ore particles, typically measuring
below 45µm, to mitigate their disposal in tailings dams. Efficient recovery of these small particles necessitates
extended exposure to a magnetic field. Experimental trials were conducted using matrices of different heights,
ranging from 220 mm to 880 mm. Findings highlight that a matrix height of 440 mm offers the most cost-
effective solution, yielding 2.5 times increase in mass recovery while improving the concentrate grades, when
compared to the standard 220 mm matrices. Notably, these matrices can be seamlessly retrofitted into existing
magnetic separators with minimal modifications.
INTRODUCTION
Ultrafine particles, smaller than 45µm, have been a chal-
lenge in the mineral processing sector for several decades.
Particularly in iron mining, these particles are removed
from the beneficiation circuit and deposited directly into
tailings dams along with the ore processing rejects because
existing concentration methods are inefficient for these par-
ticle sizes (Gonçalves 2023). In other words, these particles
do not undergo any concentration stage, even though they
may contain recoverable iron content.
However, this method of discarding ultrafine particles
has been under review for some years. Due to the challenges
of environmental licensing, companies have been striving
to minimize the amount of material dumped into tailings
dams. Consequently, mining companies have increasingly
sought innovations with the aim of reducing waste genera-
tion (Silva et al., 2023).
Ultrafine particles are typically generated in the grind-
ing stage, as it is necessary at this stage to reduce the ore to
very fine granulometries to achieve the necessary liberation
degree between iron ore and quartz (silica) (Figueira, Luz
and Almeida 2010), enabling iron concentration.
It is important to highlight that these ultrafine parti-
cles, currently discarded because they are not fully recover-
able by current methods, typically have granulometry and
liberation degree suitable for pellet feed production, below
0.150mm (PUC-RJ). Concentrating these particles repre-
sents a significant opportunity to improve the utilization of
mineral resources in a project.
One of the most traditional methods for recover-
ing iron ore is high-intensity magnetic separation. In this
methodology, the exposure time of particles to the mag-
netic field directly influences their recovery, especially for
very fine granulometries.
Therefore, one feasible proposal to increase the recov-
ery of these materials is to extend the exposure time of par-
ticles by increasing the height of the magnetic matrices, the
element where magnetic concentration occurs.