1
25-067
Overview of Iron and Steelmaking
V. Claremboux
Rolla, MO
ABSTRACT
The transformation of raw iron ore into high quality steel
can take place via several processes. A general consistent
theme involves the upgrading of the iron ores via methods
such as flotation and magnetic separation, the preparation
of an agglomerate such as via pelletization or sintering, the
smelting of the agglomerate into a high grade iron product,
and the further refining of iron into specific steel alloys.
Each of these steps admit potential for optimizations and
alternatives, and the process overall is critical to meeting the
world’s continuing iron demands.
INTRODUCTION
According to the U.S. Geological Survey in 2023, the
world’s reserves of iron ore are estimated to amount to more
than 230 billion tons of iron (USGS, 2024). While to date,
many mines around the world produce direct shipping
ores from high-grade sources, most of this iron is going to
be found in relatively low-grade deposits as higher grade
resources are depleted. Thus, the development of new tech-
nology and the proliferation of existing knowledge required
to process low-grade deposits is vital to maintaining a steady
supply of iron to the ongoing demands of society.
Most iron ore resources are sedimentary deposits con-
sisting primarily of hematite, magnetite, goethite, or sid-
erite. Common gangue materials in these deposits include
silica, kaolinite, dolomite, or calcite. The sedimentary
nature of the deposits usually means that where impuri-
ties are present, they are finely dispersed within the rocks
alongside valuable minerals. The production of a high qual-
ity iron product from the lower grade deposits requires the
removal of these impurities, whether in a mineral process-
ing plant such as a concentrator or in a smelter or other
metallurgical facility.
The choice of direct metallurgical extraction versus
mineral processing depends on the nature of the impurity
to be removed, the scale on which the process is to be under-
taken, and the desired quality and character of the final
product. In general, mineral processing techniques are the
most cost efficient method of removing common gangues
such as silica from hematite or magnetite, with siderite and
goethite presenting some additional challenges. Mineral
processing is also preferred for large scale operations.
However, direct metallurgical processing of iron ores
provides important alternatives to traditional mineral pro-
cessing technologies, whether pyrometallurgical such as
the iron nugget process (Anameric and Kawatra, 2006
Anameric et al., 2006), hydrometallurgical processes, or
bioleaching processes. Especially in the case of problem-
atic gangue materials (such as phosphates), colloidal raw
materials (such as goethite-rich tailings for reprocessing),
or where flexibility in production scaling provides value,
direct metallurgical processing of iron ores can provide
opportunities to exploit otherwise difficult materials.
In general, mineral processing techniques are preferred
for the concentration of iron ores which can be liberated
from their gangue materials. The liberation step proceeds
via a comminution circuit. Once liberated, the materials go
through series of separation steps such as magnetic separa-
tion or flotation separations. The final product of the sepa-
ration is then usually agglomerated to a target size, shape,
and overall agglomerate strength as needed by the reduction
facility. The reduction step transforms the agglomerate into
a pig iron metal product (usually via blast furnace, some-
times by direct reduction), which can be further refined
into various steel alloys.
Each step of the mineral processing flowsheet for the
refining of iron ores has seen the benefits of decades of ded-
icated effort to optimize the process for both throughput
and efficiency. This paper will highlight some of the major
successes of these efforts as they apply to modern iron ore
processing, and some of the timely opportunities which are
25-067
Overview of Iron and Steelmaking
V. Claremboux
Rolla, MO
ABSTRACT
The transformation of raw iron ore into high quality steel
can take place via several processes. A general consistent
theme involves the upgrading of the iron ores via methods
such as flotation and magnetic separation, the preparation
of an agglomerate such as via pelletization or sintering, the
smelting of the agglomerate into a high grade iron product,
and the further refining of iron into specific steel alloys.
Each of these steps admit potential for optimizations and
alternatives, and the process overall is critical to meeting the
world’s continuing iron demands.
INTRODUCTION
According to the U.S. Geological Survey in 2023, the
world’s reserves of iron ore are estimated to amount to more
than 230 billion tons of iron (USGS, 2024). While to date,
many mines around the world produce direct shipping
ores from high-grade sources, most of this iron is going to
be found in relatively low-grade deposits as higher grade
resources are depleted. Thus, the development of new tech-
nology and the proliferation of existing knowledge required
to process low-grade deposits is vital to maintaining a steady
supply of iron to the ongoing demands of society.
Most iron ore resources are sedimentary deposits con-
sisting primarily of hematite, magnetite, goethite, or sid-
erite. Common gangue materials in these deposits include
silica, kaolinite, dolomite, or calcite. The sedimentary
nature of the deposits usually means that where impuri-
ties are present, they are finely dispersed within the rocks
alongside valuable minerals. The production of a high qual-
ity iron product from the lower grade deposits requires the
removal of these impurities, whether in a mineral process-
ing plant such as a concentrator or in a smelter or other
metallurgical facility.
The choice of direct metallurgical extraction versus
mineral processing depends on the nature of the impurity
to be removed, the scale on which the process is to be under-
taken, and the desired quality and character of the final
product. In general, mineral processing techniques are the
most cost efficient method of removing common gangues
such as silica from hematite or magnetite, with siderite and
goethite presenting some additional challenges. Mineral
processing is also preferred for large scale operations.
However, direct metallurgical processing of iron ores
provides important alternatives to traditional mineral pro-
cessing technologies, whether pyrometallurgical such as
the iron nugget process (Anameric and Kawatra, 2006
Anameric et al., 2006), hydrometallurgical processes, or
bioleaching processes. Especially in the case of problem-
atic gangue materials (such as phosphates), colloidal raw
materials (such as goethite-rich tailings for reprocessing),
or where flexibility in production scaling provides value,
direct metallurgical processing of iron ores can provide
opportunities to exploit otherwise difficult materials.
In general, mineral processing techniques are preferred
for the concentration of iron ores which can be liberated
from their gangue materials. The liberation step proceeds
via a comminution circuit. Once liberated, the materials go
through series of separation steps such as magnetic separa-
tion or flotation separations. The final product of the sepa-
ration is then usually agglomerated to a target size, shape,
and overall agglomerate strength as needed by the reduction
facility. The reduction step transforms the agglomerate into
a pig iron metal product (usually via blast furnace, some-
times by direct reduction), which can be further refined
into various steel alloys.
Each step of the mineral processing flowsheet for the
refining of iron ores has seen the benefits of decades of ded-
icated effort to optimize the process for both throughput
and efficiency. This paper will highlight some of the major
successes of these efforts as they apply to modern iron ore
processing, and some of the timely opportunities which are