XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 565
industry is becoming a serious problem (Li, C. Sun, H.
Bai, J. Li, L. 2010). In order to reduce the environmental
pressures and achieve sustainability while compensating for
the depletion of high-garde deposits, a practical solution
is to reuse iron ore mining waste as a secondary resource.
However, some studies have found that wastes have an iron
grade of approximately 8% to 15% on average, and occa-
sionally as high as 25%. However, these low-grade waste
deposits generally contain a large proportion of liberated
barren gangue and it may be possible to remove this mate-
rial at a reasonably coarse size. With the passage of time,
the earth’s iron ore resources continue to decline. Due to
this reason, wastes of iron ore mines might become valuable
resources in the future. Currently, the processes for utilizing
this waste material can be mainly divided into two catego-
ries, namely iron recovery from waste and tailings and the
use of waste as raw materials.
Pre-concentration is a well-known process, and many
recovery methods have been developed for this purpose,
including gravimetric separation, magnetic separation,
and flotation separation. Pre concentration aims to remove
barren material at as coarse the particle size and as early
in the process as possible. This increases the grade of ore
proceeding to the next stage of processing (Pokrajcic and
Lewis-Gray, 2010) and may significantly reduce energy
consumption and processing costs. Pre concentration has
the potential to improve the resource efficiency by upgrad-
ing uneconomic or marginal material and/or increasing
production rates. More valuable metal may be extracted
from the resource while the processing plant treats less
tones at higher feed grades. For effective pre-concentration,
it is only necessary to have liberated gangue that can be
removed the valuable minerals do not need to be liberated.
There are several technologies that may be applicable for
pre-concentration. The suitability in each case depends on
the ore properties.
This paper looks specifically at a novel coarse mag-
netic separation based for pre-concentration extracted or
dumped waste of iron ore mines in SouthWest of Iran. Due
to the low iron content of iron ore waste, the cost of recov-
ering iron through direct feeding to the concentrate plant
is significantly high and uneconomical. Consequently,
an innovative magnetic separation technique was devel-
oped. According to this method, pre-concentration is ini-
tially undertaken to obtain a pre-concentrated high grade
product which is further used as a raw material for an exist-
ing iron ore hematite and magnetite iron ore concentrate
plant. Therefore, this technology can truly achieve full iron
recovery from waste of iron ore mine and approach zero-
tailing mining, thus resulting in substantial economic and
social benefits.
MATERIALS AND METHODS
Raw Materials
This study was done on waste rock dump of an iron ore
mine that is located in the SouthWest of Iran with around
10 million tons iron reserve and approximately 15.42%
of total iron by average. This waste material has been pro-
duced for more than twenty years. It is worth mentioning
that because of huge volume of waste material, preparing a
representative sample was too difficult. That being the case,
sampling from these piles was done in a grid according to
color and size variations. Total mass of samples was about
900 ton of waste rock material subsequently used in the
testworks.
The chemical composition of this material is pre-
sented in Table 1. The total iron content was approximately
15.42%. The mineral phases in the received waste sample
are shown in Table 2, and included quartz, hematite, and
magnetite. The waste rock particle size are k99=500 mm,
k80= 280 mm and k50= 75 mm (Table 3).
Experimental Methods
The experimental workflow is shown in Figure 1. Stages of
the workflow include crushing, screening and pre-concen-
tration by dry drum medium intensity magnetic separator
(0.3 T and axial pole arrangement) for fine portion and by
dry belt drum medium intensity magnetic separator (0.5 T
and radial pole arrangement) for coarse portion, wet grind-
ing, wet medium intensity magnetic separation (0.38 T)
and wet magnetic separation by WHIMS (1 T).
Development of Belt Drum Magnetic Separator
In order to optimum magnetic separation of coarse iron ore
particles with maximum size of 400 mm by magnetic sepa-
rator, it is needed to design and manufacture a novel mag-
netic separator .This unique path breaking high intensity
and gradient belt drum magnetic separator with a diam-
eter and length of 900 mm and 2400 mm, respectively was
Table 1. Chemical analysis of the iron ore waste samples
Fe,
%
FeO,
%
Fe2O3,
%
TiO2,
%
P2O5,
%
SO3,
%
Na2O,
%
SiO2,
%
Al2O3,
%
CaO,
%
K2O,
%
MgO,
%
MnO,
%
15.42 4.74 22.02 0.38 0.21 0.51 0.35 33.13 6.26 9.38 0.62 10.49 0.17
industry is becoming a serious problem (Li, C. Sun, H.
Bai, J. Li, L. 2010). In order to reduce the environmental
pressures and achieve sustainability while compensating for
the depletion of high-garde deposits, a practical solution
is to reuse iron ore mining waste as a secondary resource.
However, some studies have found that wastes have an iron
grade of approximately 8% to 15% on average, and occa-
sionally as high as 25%. However, these low-grade waste
deposits generally contain a large proportion of liberated
barren gangue and it may be possible to remove this mate-
rial at a reasonably coarse size. With the passage of time,
the earth’s iron ore resources continue to decline. Due to
this reason, wastes of iron ore mines might become valuable
resources in the future. Currently, the processes for utilizing
this waste material can be mainly divided into two catego-
ries, namely iron recovery from waste and tailings and the
use of waste as raw materials.
Pre-concentration is a well-known process, and many
recovery methods have been developed for this purpose,
including gravimetric separation, magnetic separation,
and flotation separation. Pre concentration aims to remove
barren material at as coarse the particle size and as early
in the process as possible. This increases the grade of ore
proceeding to the next stage of processing (Pokrajcic and
Lewis-Gray, 2010) and may significantly reduce energy
consumption and processing costs. Pre concentration has
the potential to improve the resource efficiency by upgrad-
ing uneconomic or marginal material and/or increasing
production rates. More valuable metal may be extracted
from the resource while the processing plant treats less
tones at higher feed grades. For effective pre-concentration,
it is only necessary to have liberated gangue that can be
removed the valuable minerals do not need to be liberated.
There are several technologies that may be applicable for
pre-concentration. The suitability in each case depends on
the ore properties.
This paper looks specifically at a novel coarse mag-
netic separation based for pre-concentration extracted or
dumped waste of iron ore mines in SouthWest of Iran. Due
to the low iron content of iron ore waste, the cost of recov-
ering iron through direct feeding to the concentrate plant
is significantly high and uneconomical. Consequently,
an innovative magnetic separation technique was devel-
oped. According to this method, pre-concentration is ini-
tially undertaken to obtain a pre-concentrated high grade
product which is further used as a raw material for an exist-
ing iron ore hematite and magnetite iron ore concentrate
plant. Therefore, this technology can truly achieve full iron
recovery from waste of iron ore mine and approach zero-
tailing mining, thus resulting in substantial economic and
social benefits.
MATERIALS AND METHODS
Raw Materials
This study was done on waste rock dump of an iron ore
mine that is located in the SouthWest of Iran with around
10 million tons iron reserve and approximately 15.42%
of total iron by average. This waste material has been pro-
duced for more than twenty years. It is worth mentioning
that because of huge volume of waste material, preparing a
representative sample was too difficult. That being the case,
sampling from these piles was done in a grid according to
color and size variations. Total mass of samples was about
900 ton of waste rock material subsequently used in the
testworks.
The chemical composition of this material is pre-
sented in Table 1. The total iron content was approximately
15.42%. The mineral phases in the received waste sample
are shown in Table 2, and included quartz, hematite, and
magnetite. The waste rock particle size are k99=500 mm,
k80= 280 mm and k50= 75 mm (Table 3).
Experimental Methods
The experimental workflow is shown in Figure 1. Stages of
the workflow include crushing, screening and pre-concen-
tration by dry drum medium intensity magnetic separator
(0.3 T and axial pole arrangement) for fine portion and by
dry belt drum medium intensity magnetic separator (0.5 T
and radial pole arrangement) for coarse portion, wet grind-
ing, wet medium intensity magnetic separation (0.38 T)
and wet magnetic separation by WHIMS (1 T).
Development of Belt Drum Magnetic Separator
In order to optimum magnetic separation of coarse iron ore
particles with maximum size of 400 mm by magnetic sepa-
rator, it is needed to design and manufacture a novel mag-
netic separator .This unique path breaking high intensity
and gradient belt drum magnetic separator with a diam-
eter and length of 900 mm and 2400 mm, respectively was
Table 1. Chemical analysis of the iron ore waste samples
Fe,
%
FeO,
%
Fe2O3,
%
TiO2,
%
P2O5,
%
SO3,
%
Na2O,
%
SiO2,
%
Al2O3,
%
CaO,
%
K2O,
%
MgO,
%
MnO,
%
15.42 4.74 22.02 0.38 0.21 0.51 0.35 33.13 6.26 9.38 0.62 10.49 0.17