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24-007
Additives for Magnetic Separation of Iron Ore Ultrafines
Kelly Laranjeira Nunes
Clariant Mining Solutions, Belo Horizonte, MG
Lívia Marques Faustino
Clariant Mining Solutions, Belo Horizonte, MG
Leandro Seixas Bicalho
Clariant Mining Solutions, Belo Horizonte, MG
Wagner Cláudio da Silva
Clariant Mining Solutions, The Woodlands, TX
ABSTRACT
Seeking to implement the Global Industry Standard on
Tailings Management to improve the safety of their tailings
facilities across the globe, mining companies are motivated
to invest in new technologies to recover valuable miner-
als from tailings. One solution being evaluated is the use
of magnetic separators to concentrate ultrafine tailings.
However, this approach is energy intensive as it requires
high magnetic fields to recover ultrafines, and usually results
in low mass yields. Additives that modify pulp rheology and
surface properties, or selective flocculate ultrafine particles,
were tested to enhance the performance of magnetic separa-
tion. Promising results in laboratory scale testing different
types of additives confirmed that it is possible to increase
the mass yield, keeping the selectivity of this stage.
INTRODUCTION
The Global Industry Standard on Tailings Management
sets a precedent for the safe management of tailings facili-
ties, towards the goal of zero harm to people and the envi-
ronment. Therefore, mining companies are committed to
implementing new technologies to recover valuable min-
erals from tailings, increasing production and generating
less residuals (ICMM, 2020). Also, over time, the earth’s
resources continue to decline, leading companies to turn to
tailings recovery.
Flotation and magnetic separation are the most well-
known recovery methods, but when it comes to iron ore
tailings, alumina content is usually high, and that brings
challenges to flotation, especially of kaolinite (Rodrigues,
2012 Ma, 2009). Taking that into consideration, magnetic
separation might be a great choice to concentrate iron ore
tailings. However, the intensity of the magnetic, gravity,
and hydrodynamic (for wet separators) forces are mainly
determined by the particle size. So, the finer the particles,
the less selective this process is and the higher the energy
required to concentrate the minerals. (Luo, 2016 Svoboda,
2003).
Aiming to correct that, several studies are taking place
worldwide, such as the incorporation of superconductivity,
and improved understanding of principles of HGMS (High
Gradient Magnetic Separator), among others, as shown in
Figure 1. Adding to that, we present chemical additives to
enhance ultrafine magnetic separation. They provide higher
economic value for the concentrate, by reducing contami-
nants, higher productivity, and lower residue generation,
increasing mass yield.
Those additives are based on three different action
mechanisms: dispersion, selective agglomeration, and rhe-
ology modification. Dispersing agents attach to the mineral
surface, ‘cleaning’ it and making it easier for the magnetic
Figure 1. The future trends in magnetic separation (Luo,
2016)
24-007
Additives for Magnetic Separation of Iron Ore Ultrafines
Kelly Laranjeira Nunes
Clariant Mining Solutions, Belo Horizonte, MG
Lívia Marques Faustino
Clariant Mining Solutions, Belo Horizonte, MG
Leandro Seixas Bicalho
Clariant Mining Solutions, Belo Horizonte, MG
Wagner Cláudio da Silva
Clariant Mining Solutions, The Woodlands, TX
ABSTRACT
Seeking to implement the Global Industry Standard on
Tailings Management to improve the safety of their tailings
facilities across the globe, mining companies are motivated
to invest in new technologies to recover valuable miner-
als from tailings. One solution being evaluated is the use
of magnetic separators to concentrate ultrafine tailings.
However, this approach is energy intensive as it requires
high magnetic fields to recover ultrafines, and usually results
in low mass yields. Additives that modify pulp rheology and
surface properties, or selective flocculate ultrafine particles,
were tested to enhance the performance of magnetic separa-
tion. Promising results in laboratory scale testing different
types of additives confirmed that it is possible to increase
the mass yield, keeping the selectivity of this stage.
INTRODUCTION
The Global Industry Standard on Tailings Management
sets a precedent for the safe management of tailings facili-
ties, towards the goal of zero harm to people and the envi-
ronment. Therefore, mining companies are committed to
implementing new technologies to recover valuable min-
erals from tailings, increasing production and generating
less residuals (ICMM, 2020). Also, over time, the earth’s
resources continue to decline, leading companies to turn to
tailings recovery.
Flotation and magnetic separation are the most well-
known recovery methods, but when it comes to iron ore
tailings, alumina content is usually high, and that brings
challenges to flotation, especially of kaolinite (Rodrigues,
2012 Ma, 2009). Taking that into consideration, magnetic
separation might be a great choice to concentrate iron ore
tailings. However, the intensity of the magnetic, gravity,
and hydrodynamic (for wet separators) forces are mainly
determined by the particle size. So, the finer the particles,
the less selective this process is and the higher the energy
required to concentrate the minerals. (Luo, 2016 Svoboda,
2003).
Aiming to correct that, several studies are taking place
worldwide, such as the incorporation of superconductivity,
and improved understanding of principles of HGMS (High
Gradient Magnetic Separator), among others, as shown in
Figure 1. Adding to that, we present chemical additives to
enhance ultrafine magnetic separation. They provide higher
economic value for the concentrate, by reducing contami-
nants, higher productivity, and lower residue generation,
increasing mass yield.
Those additives are based on three different action
mechanisms: dispersion, selective agglomeration, and rhe-
ology modification. Dispersing agents attach to the mineral
surface, ‘cleaning’ it and making it easier for the magnetic
Figure 1. The future trends in magnetic separation (Luo,
2016)