3584 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
ore industry in the USA. It is also important to monitor
process water chemistry for water optimisation.
Tailings Management
In general, the iron ore industry generates about 700 Mt/
annum of tailing, and most of these solids are stored in a
tailing pond. The proper management of tailings is crucial
to ensure the safe and sustainable production of metals and
minerals. As there are several tailing dam failures reported
every year, it is very crucial that dewatering and disposal
of tailing be included in the production plan (Segura et
al, 2016). The production of dry tailings for dry stacking
presents an opportunity to improve the safety and envi-
ronmental footprints of iron ore plants. Dewatering and
mineral processing technologies which produce coarse and
dewatered tailings with high underflow densities are critical
for tailings management. Such technologies include deep
cone paste thickener and fluidized bed flotation/separation
which achieve underflow densities of at least 60%. Such
technologies facilitate easier handling and safe disposal
of tailings.
Dry stacking is probably the most environmentally
friendly approach for tailings storage. Dry staking involves
depositing and compacting tailings into a mound, then
placing the stacked tailings on a liner and reclaiming on
top of native soil and vegetation. The advantages of dry
stacking include elimination of a dam for tailings storage,
consequently eliminating the risk of dam failure, and miti-
gates long-term storage concerns. These stacked tailings can
be placed on a liner and reclaimed on top with native soil
and vegetation.
To enable circular economy, the tailings may be con-
sidered as an alternative source of valuable metals. Iron
ore processing plants contain silica which may be used in
the construction industry. The tailings may also be used as
feedstock to produce commercial grade silica, etc for sale.
Alternative Sources of Iron—Historical Tailings and
Mine Tailings Reprocessing
Over the years, Minnesota has accumulated over one bil-
lion tons of natural iron ore tailings basins and stockpiles
containing economically recoverable iron. Companies like
Magnetation LLC, a joint venture between Magnetation,
Inc. and AK Steel Corp., were reprocessing these tailings to
recover high-grade iron ore fines. Magnetation LLC estab-
lished a new iron ore concentrate plant near Grand Rapids
in 2014. The company also owned and operated plants in
Keewatin and Bovey, Minnesota. Another joint venture,
Mining Resources LLC, involving Steel Dynamics, Inc. and
Magnetation Inc., were similarly engaged in producing iron
ore concentrates from tailings basins. Their concentrates
were shipped to Mesabi Nugget, a pig iron nugget opera-
tion that was jointly operated by Steel Dynamics and Kobe
Steel near Hoyt Lakes, Minnesota. Overall, these endeav-
ors highlight the importance of reprocessing historical and
mine tailings to extract valuable iron resources (Minnesota
Department of Natural Resources, 2016).
In 2022, MagIron was formed to assess the potential
of restarting Plant 4 in Grand Rapids, Minnesota—an iron
ore concentrator initially designed for an annualized run-
rate of 2.0 mtpa. MagIron envisions expanding the plant to
3.0 mtpa with low capital intensity. The company aims to
process waste materials from historical mining operations
at Plant 4, converting discarded materials into high-grade,
low-impurity iron ore concentrate. In 2023, MagIron
announced the completion of metallurgical test work for
its Plant 4 iron ore project. The results introduced a new
process flowsheet to produce direct reduced (DR) grade
iron concentrate. This high-grade concentrate, if pelletized,
could serve as suitable feedstock for Electric Arc Furnaces
(EAF). MagIron employs proprietary mineral processing
technology to recover high-grade iron ore concentrate from
low-grade hematite iron resources, encompassing tailing
basins, lean ore stockpiles, and virgin ore bodies (MagIron
USA, 2023).
Specialty Reagent Development
Reagent selection in iron ore processing depends on ore
mineralogy, gangue type, particle size distribution of the
ore and flowsheet employed. All RCF in the USA iron ore
operations utilize amine as silica collector and MIBC as
frother. The main problem associated with amine collectors
is inherent frothing properties making it difficult to con-
trol and optimise the pulp phase processes, independent
of the froth phase processes. Furthermore, the collectors
are expensive and may have poor selectivity. There seems to
be no consensus about the biodegradability and toxicity of
amine collectors. There is therefore a need for the develop-
ment of high performing, environmentally friendly, green
surfactants for the iron ore industry.
CONCLUSION
The iron and steel industry plays a significant role in the
US economy. The industry faces several economic, tech-
nical, social, and environmental challenges. Some of the
challenges identified in this paper are declining ore grades,
mineralogically complex ores, stringent environmental reg-
ulations, competition from international players, Fe recov-
ery losses in concentrators, etc. The US iron ore industry
must accelerate the adoption of emerging and sustainable
ore industry in the USA. It is also important to monitor
process water chemistry for water optimisation.
Tailings Management
In general, the iron ore industry generates about 700 Mt/
annum of tailing, and most of these solids are stored in a
tailing pond. The proper management of tailings is crucial
to ensure the safe and sustainable production of metals and
minerals. As there are several tailing dam failures reported
every year, it is very crucial that dewatering and disposal
of tailing be included in the production plan (Segura et
al, 2016). The production of dry tailings for dry stacking
presents an opportunity to improve the safety and envi-
ronmental footprints of iron ore plants. Dewatering and
mineral processing technologies which produce coarse and
dewatered tailings with high underflow densities are critical
for tailings management. Such technologies include deep
cone paste thickener and fluidized bed flotation/separation
which achieve underflow densities of at least 60%. Such
technologies facilitate easier handling and safe disposal
of tailings.
Dry stacking is probably the most environmentally
friendly approach for tailings storage. Dry staking involves
depositing and compacting tailings into a mound, then
placing the stacked tailings on a liner and reclaiming on
top of native soil and vegetation. The advantages of dry
stacking include elimination of a dam for tailings storage,
consequently eliminating the risk of dam failure, and miti-
gates long-term storage concerns. These stacked tailings can
be placed on a liner and reclaimed on top with native soil
and vegetation.
To enable circular economy, the tailings may be con-
sidered as an alternative source of valuable metals. Iron
ore processing plants contain silica which may be used in
the construction industry. The tailings may also be used as
feedstock to produce commercial grade silica, etc for sale.
Alternative Sources of Iron—Historical Tailings and
Mine Tailings Reprocessing
Over the years, Minnesota has accumulated over one bil-
lion tons of natural iron ore tailings basins and stockpiles
containing economically recoverable iron. Companies like
Magnetation LLC, a joint venture between Magnetation,
Inc. and AK Steel Corp., were reprocessing these tailings to
recover high-grade iron ore fines. Magnetation LLC estab-
lished a new iron ore concentrate plant near Grand Rapids
in 2014. The company also owned and operated plants in
Keewatin and Bovey, Minnesota. Another joint venture,
Mining Resources LLC, involving Steel Dynamics, Inc. and
Magnetation Inc., were similarly engaged in producing iron
ore concentrates from tailings basins. Their concentrates
were shipped to Mesabi Nugget, a pig iron nugget opera-
tion that was jointly operated by Steel Dynamics and Kobe
Steel near Hoyt Lakes, Minnesota. Overall, these endeav-
ors highlight the importance of reprocessing historical and
mine tailings to extract valuable iron resources (Minnesota
Department of Natural Resources, 2016).
In 2022, MagIron was formed to assess the potential
of restarting Plant 4 in Grand Rapids, Minnesota—an iron
ore concentrator initially designed for an annualized run-
rate of 2.0 mtpa. MagIron envisions expanding the plant to
3.0 mtpa with low capital intensity. The company aims to
process waste materials from historical mining operations
at Plant 4, converting discarded materials into high-grade,
low-impurity iron ore concentrate. In 2023, MagIron
announced the completion of metallurgical test work for
its Plant 4 iron ore project. The results introduced a new
process flowsheet to produce direct reduced (DR) grade
iron concentrate. This high-grade concentrate, if pelletized,
could serve as suitable feedstock for Electric Arc Furnaces
(EAF). MagIron employs proprietary mineral processing
technology to recover high-grade iron ore concentrate from
low-grade hematite iron resources, encompassing tailing
basins, lean ore stockpiles, and virgin ore bodies (MagIron
USA, 2023).
Specialty Reagent Development
Reagent selection in iron ore processing depends on ore
mineralogy, gangue type, particle size distribution of the
ore and flowsheet employed. All RCF in the USA iron ore
operations utilize amine as silica collector and MIBC as
frother. The main problem associated with amine collectors
is inherent frothing properties making it difficult to con-
trol and optimise the pulp phase processes, independent
of the froth phase processes. Furthermore, the collectors
are expensive and may have poor selectivity. There seems to
be no consensus about the biodegradability and toxicity of
amine collectors. There is therefore a need for the develop-
ment of high performing, environmentally friendly, green
surfactants for the iron ore industry.
CONCLUSION
The iron and steel industry plays a significant role in the
US economy. The industry faces several economic, tech-
nical, social, and environmental challenges. Some of the
challenges identified in this paper are declining ore grades,
mineralogically complex ores, stringent environmental reg-
ulations, competition from international players, Fe recov-
ery losses in concentrators, etc. The US iron ore industry
must accelerate the adoption of emerging and sustainable