Iron ores are rocks and minerals from which
metallic iron can be economically extracted.
The ores are usually rich in iron oxides and
vary in color from dark grey, bright yellow,
deep purple, to rusty red. The iron itself
is usually found in the form of magnetite
(Fe
3O
4), hematite (Fe
2O
3), goethite), limonite.n(H2O)) or siderite.
Ores carrying very high quantities of hematite
or magnetite are known as "natural ore" or
"direct shipping ore", meaning they can be
fed directly into iron-making blast furnaces.
Most reserves of such ore have now been depleted.
Iron ore is the raw material used to make
pig iron, which is one of the main raw materials
to make steel. 98% of the mined iron ore is
used to make steel. Indeed, it has been argued
that iron ore is "more integral to the global
economy than any other commodity, except perhaps
oil".
Sources
Metallic iron is virtually unknown on the
surface of the Earth except as iron-nickel
alloys from meteorites and very rare forms
of deep mantle xenoliths. Although iron is
the fourth most abundant element in the Earth's
crust, comprising about 5%, the vast majority
is bound in silicate or more rarely carbonate
minerals. The thermodynamic barriers to separating
pure iron from these minerals are formidable
and energy intensive, therefore all sources
of iron used by human industry exploit comparatively
rarer iron oxide minerals, primarily hematite.
Prior to the industrial revolution, most iron
was obtained from widely available goethite
or bog ore, for example during the American
Revolution and the Napoleonic wars. Prehistoric
societies used laterite as a source of iron
ore. Historically, much of the iron ore utilized
by industrialized societies has been mined
from predominantly hematite deposits with
grades in excess of 70% Fe. These deposits
are commonly referred to as "direct shipping
ores" or "natural ores". Increasing iron ore
demand, coupled with the depletion of high-grade
hematite ores in the United States, after
World War II led to development of lower-grade
iron ore sources, principally the utilization
of magnetite and taconite.
Iron ore mining methods vary by the type of
ore being mined. There are four main types
of iron ore deposits worked currently, depending
on the mineralogy and geology of the ore deposits.
These are magnetite, titanomagnetite, massive
hematite and pisolitic ironstone deposits.
Banded iron formations
Banded iron formations are sedimentary rocks
containing more than 15% iron composed predominantly
of thinly bedded iron minerals and silica.
Banded iron formations occur exclusively in
Precambrian rocks, and are commonly weakly
to intensely metamorphosed. Banded iron formations
may contain iron in carbonates or silicates,
but in those mined as iron ores, oxides are
the principal iron mineral. Banded iron formations
are known as taconite within North America.
The mining involves moving tremendous amounts
of ore and waste. The waste comes in two forms,
non-ore bedrock in the mine, and unwanted
minerals which are an intrinsic part of the
ore rock itself. The mullock is mined and
piled in waste dumps, and the gangue is separated
during the beneficiation process and is removed
as tailings. Taconite tailings are mostly
the mineral quartz, which is chemically inert.
This material is stored in large, regulated
water settling ponds.
Magnetite ores
The key economic parameters for magnetite
ore being economic are the crystallinity of
the magnetite, the grade of the iron within
the banded iron formation host rock, and the
contaminant elements which exist within the
magnetite concentrate. The size and strip
ratio of most magnetite resources is irrelevant
as a banded iron formation can be hundreds
of meters thick, extend hundreds of kilometers
along strike, and can easily come to more
than three billion or more tonnes of contained
ore.
The typical grade of iron at which a magnetite-bearing
banded iron formation becomes economic is
roughly 25% iron, which can generally yield
a 33% to 40% recovery of magnetite by weight,
to produce a concentrate grading in excess
of 64% iron by weight. The typical magnetite
iron ore concentrate has less than 0.1% phosphorus,
3–7% silica and less than 3% aluminium.
Currently magnetite iron ore is mined in Minnesota
and Michigan in the U.S., Eastern Canada and
North Sweden. Magnetite bearing banded iron
formation is currently mined extensively in
Brazil, which exports significant quantities
to Asia, and there is a nascent and large
magnetite iron ore industry in Australia.
Direct shipping ores
Direct shipping iron ore deposits are currently
exploited on all continents except Antarctica,
with the largest intensity in South America,
Australia and Asia. Most large hematite iron
ore deposits are sourced from altered banded
iron formations and rarely igneous accumulations.
DSO deposits are typically rarer than the
magnetite-bearing BIF or other rocks which
form its main source or protolith rock, but
are considerably cheaper to mine and process
as they require less beneficiation due to
the higher iron content. However, DSO ores
can contain significantly higher concentrations
of penalty elements, typically being higher
in phosphorus, water content and aluminum.
Export grade DSO ores are generally in the
62–64% Fe range.
Magmatic magnetite ore deposits
Occasionally granite and ultrapotassic igneous
rocks segregate magnetite crystals and form
masses of magnetite suitable for economic
concentration. A few iron ore deposits, notably
in Chile, are formed from volcanic flows containing
significant accumulations of magnetite phenocrysts.
Chilean magnetite iron ore deposits within
the Atacama Desert have also formed alluvial
accumulations of magnetite in streams leading
from these volcanic formations.
Some magnetite skarn and hydrothermal deposits
have been worked in the past as high-grade
iron ore deposits requiring little beneficiation.
There are several granite-associated deposits
of this nature in Malaysia and Indonesia.
Other sources of magnetite iron ore include
metamorphic accumulations of massive magnetite
ore such as at Savage River, Tasmania, formed
by shearing of ophiolite ultramafics.
Another, minor, source of iron ores are magmatic
accumulations in layered intrusions which
contain a typically titanium-bearing magnetite
often with vanadium. These ores form a niche
market, with specialty smelters used to recover
the iron, titanium and vanadium. These ores
are beneficiated essentially similar to banded
iron formation ores, but usually are more
easily upgraded via crushing and screening.
The typical titanomagnetite concentrate grades
57% Fe, 12% Ti and 0.5% V
2O
5.
Beneficiation
Lower-grade sources of iron ore generally
require beneficiation, using techniques like
crushing, milling, gravity or heavy media
separation, screening, and silica froth flotation
to improve the concentration of the ore and
remove impurities. The results, high quality
fine ore powders, are known as fines.
Magnetite
Magnetite is magnetic, and hence easily separated
from the gangue minerals and capable of producing
a high-grade concentrate with very low levels
of impurities.
The grain size of the magnetite and its degree
of commingling with the silica groundmass
determine the grind size to which the rock
must be comminuted to enable efficient magnetic
separation to provide a high purity magnetite
concentrate. This determines the energy inputs
required to run a milling operation.
Mining of banded iron formations involves
coarse crushing and screening, followed by
rough crushing and fine grinding to comminute
the ore to the point where the crystallized
magnetite and quartz are fine enough that
the quartz is left behind when the resultant
powder is passed under a magnetic separator.
Generally most magnetite banded iron formation
deposits must be ground to between 32 and
45 micrometers in order to produce a low-silica
magnetite concentrate. Magnetite concentrate
grades are generally in excess of 70% iron
by weight and usually are low phosphorus,
low aluminium, low titanium and low silica
and demand a premium price.
Hematite
Due to the high density of hematite relative
to associated silicate gangue, hematite beneficiation
usually involves a combination of beneficiation
techniques.
One method relies on passing the finely crushed
ore over a bath of solution containing bentonite
or other agent which increases the density
of the solution. When the density of the solution
is properly calibrated, the hematite will
sink and the silicate mineral fragments will
float and can be removed.
Production and consumption
Iron is the world's most commonly used metal
- steel, of which iron ore is the key ingredient,
representing almost 95% of all metal used
per year. It is used primarily in structural
engineering applications and in maritime purposes,
automobiles, and general industrial applications.
Iron-rich rocks are common worldwide, but
ore-grade commercial mining operations are
dominated by the countries listed in the table
aside. The major constraint to economics for
iron ore deposits is not necessarily the grade
or size of the deposits, because it is not
particularly hard to geologically prove enough
tonnage of the rocks exist. The main constraint
is the position of the iron ore relative to
market, the cost of rail infrastructure to
get it to market and the energy cost required
to do so.
Mining iron ore is a high volume low margin
business, as the value of iron is significantly
lower than base metals. It is highly capital
intensive, and requires significant investment
in infrastructure such as rail in order to
transport the ore from the mine to a freight
ship. For these reasons, iron ore production
is concentrated in the hands of a few major
players.
World production averages two billion metric
tons of raw ore annually. The world's largest
producer of iron ore is the Brazilian mining
corporation Vale, followed by Anglo-Australian
companies BHP Billiton and Rio Tinto Group.
A further Australian supplier, Fortescue Metals
Group Ltd has helped bring Australia's production
to second in the world.
The seaborne trade in iron ore, that is, iron
ore to be shipped to other countries, was
849m tonnes in 2004. Australia and Brazil
dominate the seaborne trade, with 72% of the
market. BHP, Rio and Vale control 66% of this
market between them.
In Australia iron ore is won from three main
sources: pisolite "channel iron deposit" ore
derived by mechanical erosion of primary banded-iron
formations and accumulated in alluvial channels
such as at Pannawonica, Western Australia;
and the dominant metasomatically-altered banded
iron formation related ores such as at Newman,
the Chichester Range, the Hamersley Range
and Koolyanobbing, Western Australia. Other
types of ore are coming to the fore recently,
such as oxidised ferruginous hardcaps, for
instance laterite iron ore deposits near Lake
Argyle in Western Australia.
The total recoverable reserves of iron ore
in India are about 9,602 million tones of
hematite and 3,408 million tones of magnetite.Chhattisgarh,
Madhya Pradesh, Karnataka, Jharkhand, Odisha,
Goa, Maharashtra, Andhra Pradesh, Kerala,
Rajasthan and Tamil Nadu are the principal
Indian producers of iron ore. World consumption
of iron ore grows 10% per annum on average
with the main consumers being China, Japan,
Korea, the United States and the European
Union.
China is currently the largest consumer of
iron ore, which translates to be the world's
largest steel producing country. It is also
the largest importer, buying 52% of the seaborne
trade in iron ore in 2004. China is followed
by Japan and Korea, which consume a significant
amount of raw iron ore and metallurgical coal.
In 2006, China produced 588 million tons of
iron ore, with an annual growth of 38%.
Iron ore market
Over the last 40 years, iron ore prices have
been decided in closed-door negotiations between
the small handful of miners and steelmakers
which dominate both spot and contract markets.
Traditionally, the first deal reached between
these two groups sets a benchmark to be followed
by the rest of the industry.
This benchmark system has however in recent
years begun to break down, with participants
along both demand and supply chains calling
for a shift to short term pricing. Given that
most other commodities already have a mature
market-based pricing system, it is natural
for iron ore to follow suit. To answer increasing
market demands for more transparent pricing,
a number of financial exchanges and/or clearing
houses around the world have offered iron
ore swaps clearing. The CME group, SGX, London
Clearing House, NOS Group and ICEX all offer
cleared swaps based on The Steel Index's iron
ore transaction data. The CME also offers
a Platts based swap, in addition to their
TSI swap clearing. The ICE offers a Platts
based swap clearing service also. The swaps
market has grown quickly, with liquidity clustering
around TSI's pricing. By April 2011, over
US$5.5 billion worth of iron ore swaps have
been cleared basis TSI prices. By August 2012,
in excess of one million tonnes of swaps trading
per day was taking place regularly, basis
TSI.
A relatively new development has also been
the introduction of iron ore options, in addition
to swaps. The CME group has been the venue
most utilised for clearing of options written
against TSI, with open interest at over 12,000
lots in August 2012.
Singapore Mercantile Exchange has launched
the world first global iron ore futures contract,
based on the Metal Bulletin Iron Ore Index
which utilizes daily price data from a broad
spectrum of industry participants and independent
Chinese steel consultancy and data provider
Shanghai Steelhome's widespread contact base
of steel producers and iron ore traders across
China. The futures contract has seen monthly
volumes over 1.5 million tonnes after eight
months of trading.
This move follows a switch to index-based
quarterly pricing by the world's three largest
iron ore miners - Vale, Rio Tinto and BHP
Billiton - in early 2010, breaking a 40-year
tradition of benchmark annual pricing.
Available iron ore resources
Available world iron ore resources
The Iron ore reserves at present seem quite
vast, but some are starting to suggest that
the math of continual exponential increase
in consumption can even make this resource
seem quite finite. For instance, Lester Brown
of the Worldwatch Institute has suggested
iron ore could run out within 64 years based
on an extremely conservative extrapolation
of 2% growth per year.
Australia
Geoscience Australia calculates that the country's
"economic demonstrated resources" of iron
currently amount to 24 gigatonnes, or 24 billion
tonnes. The current production rate from the
Pilbara region of Western Australia is approximately
430 million tonnes a year and rising. Experts
Dr Gavin Mudd and Jonathon Law expect it to
be gone within 30 to 50 years and 56 years.
These estimates require on-going review to
take into account shifting demand for lower
grade iron ore and improving mining and recovery
techniques.
Pilbara deposit
In 2011, leading Pilbara based iron ore miners
- Rio Tinto, BHP Billiton and Fortescue Metals
Group - all announced significant capital
investment in the development of existing
and new mines and associated infrastructure.
Collectively this would amount to the production
of 1,000 million tonnes per year by 2020.
Practically that would require a doubling
of production capacity from a current production
level of 470 Mt/y to 1,000 Mt/y. These figures
are based on the current production rates
of Rio 220 Mt/y, BHP 180 Mt/y, FMG 55 Mt/y
and Other 15 Mt/y increasing to Rio 353 Mt/y,
BHP 356 Mt/y, FMG 155 Mt/y and Other 140 Mt/y.
A production rate of 1,000 Mt/y would require
a significant increase in production from
existing mines and the opening of a significant
number of new mines. Further, a significant
increase in the capacity of rail and port
infrastructure would also be required. For
example, Rio would be required to expand its
port operations at Dampier and Cape Lambert
by 140 Mt/y. BHP would be required to expand
its Port Hedland port operations by 180 Mt/y.
FMG would be required to expand its port operations
at Port Hedland by 100 Mt/y. That's an increase
of 420 Mt/y in port capacity by the three
majors Rio, BHP and FMG and about at least
110 Mt/y from the non-major producers. Based
on the rule-of-thumb of 50 Mt/y per car dumper,
reclaimer and ship-loader the new production
would require approximately 10 new car dumpers,
reclaimers and ship-loaders.
New rail capacity would also be required.
Based on the rule-of-thumb of 100 Mt/y per
rail line, increasing production by approximately
500 Mt/y would require 5 new single rail lines.
One scenario is an extra rail line for all
the majors: BHP, Rio, FMG and at least two
new lines. New lines have been proposed by
Hancock to service the Roy Hill mine and QR
National to service non-major producers.
A 1,000 Mt/y production rate needs to be further
considered by proponents and government. Areas
of further consideration include new port
space at Anketell to service the West Pilbara
mines, growth at Port Hedland, rail rationalisation
and the regulatory approval requirements for
opening and maintaining a ground disturbance
footprint that supports 1,000 Mt/y of production
including, amongst other things, native title,
aboriginal heritage and environmental protection
outcomes.
Smelting
Iron ores consist of oxygen and iron atoms
bonded together into molecules. To convert
it to metallic iron it must be smelted or
sent through a direct reduction process to
remove the oxygen. Oxygen-iron bonds are strong,
and to remove the iron from the oxygen, a
stronger elemental bond must be presented
to attach to the oxygen. Carbon is used because
the strength of a carbon-oxygen bond is greater
than that of the iron-oxygen bond, at high
temperatures. Thus, the iron ore must be powdered
and mixed with coke, to be burnt in the smelting
process.
However, it is not entirely as simple as that.
Carbon monoxide is the primary ingredient
of chemically stripping oxygen from iron.
Thus, the iron and carbon smelting must be
kept at an oxygen deficient state to promote
burning of carbon to produce CO not CO
2.
Air blast and charcoal: 2 C + O2 → 2 CO.
Carbon monoxide is the principal reduction
agent.
Stage One: 3 Fe2O3 + CO → 2 Fe3O4 + CO2
Stage Two: Fe3O4 + CO → 3 FeO + CO2
Stage Three: FeO + CO → Fe + CO2
Limestone calcining: CaCO3 → CaO + CO2
Lime acting as flux: CaO + SiO2 → CaSiO3
Trace elements
The inclusion of even small amounts of some
elements can have profound effects on the
behavioral characteristics of a batch of iron
or the operation of a smelter. These effects
can be both good and bad, some catastrophically
bad. Some chemicals are deliberately added
such as flux which makes a blast furnace more
efficient. Others are added because they make
the iron more fluid, harder, or give it some
other desirable quality. The choice of ore,
fuel, and flux determine how the slag behaves
and the operational characteristics of the
iron produced. Ideally iron ore contains only
iron and oxygen. In reality this is rarely
the case. Typically, iron ore contains a host
of elements which are often unwanted in modern
steel.
Silicon
Silica (SiO
2) is almost always present in iron ore. Most
of it is slagged off during the smelting process.
At temperatures above 1300 °C some will be
reduced and form an alloy with the iron. The
hotter the furnace, the more silicon will
be present in the iron. It is not uncommon
to find up to 1.5% Si in European cast iron
from the 16th to 18th centuries.
The major effect of silicon is to promote
the formation of grey iron. Grey iron is less
brittle and easier to finish than white iron.
It is preferred for casting purposes for this
reason. Turner reported that silicon also
reduces shrinkage and the formation of blowholes,
lowering the number of bad castings.
Phosphorus
Phosphorus has four major effects on iron:
increased hardness and strength, lower solidus
temperature, increased fluidity, and cold
shortness. Depending on the use intended for
the iron, these effects are either good or
bad. Bog ore often has a high phosphorus content.
The strength and hardness of iron increases
with the concentration of phosphorus. 0.05%
phosphorus in wrought iron makes it as hard
as medium carbon steel. High phosphorus iron
can also be hardened by cold hammering. The
hardening effect is true for any concentration
of phosphorus. The more phosphorus, the harder
the iron becomes and the more it can be hardened
by hammering. Modern steel makers can increase
hardness by as much as 30%, without sacrificing
shock resistance by maintaining phosphorus
levels between 0.07 and 0.12%. It also increases
the depth of hardening due to quenching, but
at the same time also decreases the solubility
of carbon in iron at high temperatures. This
would decrease its usefulness in making blister
steel, where the speed and amount of carbon
absorption is the overriding consideration.
The addition of phosphorus has a down side.
At concentrations higher than 0.2% iron becomes
increasingly cold short, or brittle at low
temperatures. Cold short is especially important
for bar iron. Although bar iron is usually
worked hot, its uses often require it to be
tough, bendable, and resistant to shock at
room temperature. A nail that shattered when
hit with a hammer or a carriage wheel that
broke when it hit a rock would not sell well.
High enough concentrations of phosphorus render
any iron unusable. The effects of cold shortness
are magnified by temperature. Thus, a piece
of iron that is perfectly serviceable in summer,
might become extremely brittle in winter.
There is some evidence that during the Middle
Ages the very wealthy may have had a high
phosphorus sword for summer and a low phosphorus
sword for winter.
Careful control of phosphorus can be of great
benefit in casting operations. Phosphorus
depresses the liquidus temperature, allowing
the iron to remain molten for longer and increases
fluidity. The addition of 1% can double the
distance molten iron will flow. The maximum
effect, about 500 °C, is achieved at a concentration
of 10.2%. For foundry work Turner felt the
ideal iron had 0.2–0.55% phosphorus. The
resulting iron filled molds with fewer voids
and also shrank less. In the 19th century
some producers of decorative cast iron used
iron with up to 5% phosphorus. The extreme
fluidity allowed them to make very complex
and delicate castings. But, they could not
be weight bearing, as they had no strength.
There are two remedies for high phosphorus
iron. The oldest, and easiest, is avoidance.
If the iron that the ore produced was cold
short, one would search for a new source of
iron ore. The second method involves oxidizing
the phosphorus during the fining process by
adding iron oxide. This technique is usually
associated with puddling in the 19th century,
and may not have been understood earlier.
For instance Isaac Zane, the owner of Marlboro
Iron Works did not appear to know about it
in 1772. Given Zane's reputation for keeping
abreast of the latest developments, the technique
was probably unknown to the ironmasters of
Virginia and Pennsylvania.
Phosphorus is a deleterious contaminant because
it makes steel brittle, even at concentrations
of as little as 0.6%. Phosphorus cannot be
easily removed by fluxing or smelting, and
so iron ores must generally be low in phosphorus
to begin with. The iron pillar of India which
does not rust is protected by a phosphoric
composition. Phosphoric acid is used as a
rust converter because phosphoric iron is
less susceptible to oxidation.
Aluminium
Small amounts of aluminium are present in
many ores including iron ore, sand and some
limestones. The former can be removed by washing
the ore prior to smelting. Until the introduction
of brick lined furnaces, the amount of aluminum
contamination was small enough that it did
not have an effect on either the iron or slag.
However, when brick began to be used for hearths
and the interior of blast furnaces, the amount
of aluminium contamination increased dramatically.
This was due to the erosion of the furnace
lining by the liquid slag.
Aluminium is very hard to reduce. As a result
aluminium contamination of the iron is not
a problem. However, it does increase the viscosity
of the slag. This will have a number of adverse
effects on furnace operation. The thicker
slag will slow the descent of the charge,
prolonging the process. High aluminium will
also make it more difficult to tap off the
liquid slag. At the extreme this could lead
to a frozen furnace.
There are a number of solutions to a high
aluminium slag. The first is avoidance; don't
use ore or a lime source with a high aluminium
content. Increasing the ratio of lime flux
will decrease the viscosity.
Sulfur
Sulfur is a frequent contaminant in coal.
It is also present in small quantities in
many ores, but can be removed by calcining.
Sulfur dissolves readily in both liquid and
solid iron at the temperatures present in
iron smelting. The effects of even small amounts
of sulfur are immediate and serious. They
were one of the first worked out by iron makers.
Sulfur causes iron to be red or hot short.
Hot short iron is brittle when hot. This was
a serious problem as most iron used during
the 17th and 18th century was bar or wrought
iron. Wrought iron is shaped by repeated blows
with a hammer while hot. A piece of hot short
iron will crack if worked with a hammer. When
a piece of hot iron or steel cracks the exposed
surface immediately oxidizes. This layer of
oxide prevents the mending of the crack by
welding. Large cracks cause the iron or steel
to break up. Smaller cracks can cause the
object to fail during use. The degree of hot
shortness is in direct proportion to the amount
of sulfur present. Today iron with over 0.03%
sulfur is avoided.
Hot short iron can be worked, but it has to
be worked at low temperatures. Working at
lower temperatures requires more physical
effort from the smith or forgeman. The metal
must be struck more often and harder to achieve
the same result. A mildly sulfur contaminated
bar can be worked, but it requires a great
deal more time and effort.
In cast iron sulfur promotes the formation
of white iron. As little as 0.5% can counteract
the effects of slow cooling and a high silicon
content. White cast iron is more brittle,
but also harder. It is generally avoided,
because it is difficult to work, except in
China where high sulfur cast iron, some as
high as 0.57%, made with coal and coke, was
used to make bells and chimes. According to
Turner, good foundry iron should have less
than 0.15% sulfur. In the rest of the world
a high sulfur cast iron can be used for making
castings, but will make poor wrought iron.
There are a number of remedies for sulfur
contamination. The first, and the one most
used in historic and prehistoric operations,
is avoidance. Coal was not used in Europe
as a fuel for smelting because it contains
sulfur and therefore causes hot short iron.
If an ore resulted in hot short metal, ironmasters
looked for another ore. When mineral coal
was first used in European blast furnaces
in 1709, it was coked. Only with the introduction
of hot blast from 1829 was raw coal used.
Sulfur can be removed from ores by roasting
and washing. Roasting oxidizes sulfur to form
sulfur dioxide which either escapes into the
atmosphere or can be washed out. In warm climates
it is possible to leave pyritic ore out in
the rain. The combined action of rain, bacteria,
and heat oxidize the sulfides to sulfates,
which are water soluble. However, historically,
iron sulfide (iron pyrite FeS
2), though a common iron mineral, has not
been used as an ore for the production of
iron metal. Natural weathering was also used
in Sweden. The same process, at geological
speed, results in the gossan limonite ores.
The importance attached to low sulfur iron
is demonstrated by the consistently higher
prices paid for the iron of Sweden, Russia,
and Spain from the 16th to 18th centuries.
Today sulfur is no longer a problem. The modern
remedy is the addition of manganese. But,
the operator must know how much sulfur is
in the iron because at least five times as
much manganese must be added to neutralize
it. Some historic irons display manganese
levels, but most are well below the level
needed to neutralize sulfur.
See also
Iron ore in Africa
Notes
References
External links
History of the Iron Ore Trade on the Great
Lakes
"Pioneers of the Cleveland iron trade" by
J. S. Jeans 1875
Iron Ore Price and Historical Chart
Iron Mines of NY/NJ
Iron ore capacity by major world producer
