Rare Earth Metals
Introduction
A rare-earth element (REE) or rare-earth
metal (REM), as defined by IUPAC, is one
of a set of seventeen chemical elements in the periodic table,
specifically the fifteen lanthanides, as well
as scandium and yttrium. Scandium
and yttrium are considered rare-earth elements because they tend to occur in
the same ore deposits
as the lanthanides and exhibit similar chemical properties. For the same set of
mineralogical, chemical, physical (especially electron shell configuration),
and related reasons, a broader definition of rare earth elements including the actinides is
encountered in some cases. Thorium is a
significant component of monazite and
other important rare earth minerals, and uranium and
decay products are found in others. Both series of elements begin on
the periodic table in group 3 under yttrium and scandium.
The 17 rare-earth elements are cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum(La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb),
and yttrium (Y).
Despite their name, rare-earth elements are – with
the exception of the radioactive promethium
– relatively plentiful in Earth's crust, with
cerium being the 25th most abundant element at 68 parts per million, more abundant than
copper. They are not especially rare, but they tend to occur together in nature
and are difficult to separate from one another. However, because of their geochemical properties,
rare-earth elements are typically dispersed and not often found concentrated as
rare-earth minerals in economically exploitable ore deposits. The
first such mineral discovered (1787) was gadolinite, a
mineral composed of cerium, yttrium, iron, silicon, and other elements. This
mineral was extracted from a mine in the village of Ytterby in
Sweden; four of the rare-earth elements bear names derived from this single
location.
Utilization and Uses
Rare earths are a series of chemical elements found in the Earth’s crust
that are vital to many modern technologies, including consumer electronics,
computers and networks, communications, clean energy, advanced transportation,
health care, environmental mitigation, national defense, and many others.
Because of their unique magnetic, luminescent, and electrochemical
properties, these elements help make many technologies perform with reduced
weight, reduced emissions, and energy consumption; or give them greater efficiency,
performance, miniaturization, speed, durability, and thermal stability. Rare
earth-enabled products and technologies help fuel global economic growth,
maintain high standards of living, and even save lives.
There are 17 elements that are considered to be rare earth elements—15
elements in the lanthanide series and two additional elements that share
similar chemical properties. They are listed below in order of atomic number
(Z):
The uses, applications, and demand
for rare-earth elements have expanded over the years. This is particularly due
to the uses of rare-earth elements in low-carbon technologies. Some important
uses of rare-earth elements are applicable to the production of
high-performance magnets, catalysts, alloys, glasses, and electronics. Nd is
important in magnet production. Rare-earth elements in this category are used
in the electric motors of hybrid vehicles, wind turbines, hard disc drives,
portable electronics, microphones, speakers. Ce and La are important as
catalysts, and are used for petroleum refining and as diesel additives. Ce, La
and Nd are important in alloy making, and in the production of fuel cells and Nickel-metal hydride batteries. Ce, Ga and Nd are important in
electronics and are used in the production of LCD and plasma screens, fiber
optics, lasers, as well as in medical imaging. Additional uses for earth
elements are as tracers in medical applications, fertilizers, and in water
treatment. REEs have been used in agriculture to increase plant growth,
productivity, and stress resistance seemingly without negative effects for
human and animal consumption. REEs are used in agriculture through REE-enriched
fertilizers which is a widely used practice in China.In addition; REEs are feed
additives for livestock which has resulted in increased production such as
larger animals and a higher production of eggs and dairy products. However,
this practice has resulted in REE bio-accumulation within livestock and has
impacted vegetation and algae growth in this agricultural area. Additionally
while no ill effects have been observed at current low concentrations the
effects over the long term and with accumulation over time are unknown
prompting some calls for more research into their possible effects.
Geology and rare earth metals
The application of rare-earth elements to geology
is important to understanding the petrological processes of igneous, sedimentary and metamorphic rock
formation. In geochemistry,
rare-earth elements can be used to infer the petrological mechanisms that have
affected a rock due to the subtle atomic size differences between the
elements, which causes preferential fractionation of some rare earths relative to others depending
on the processes at work.
In geochemistry, rare-earth elements are typically
presented in normalized "spider" diagrams, in which concentration of
rare-earth elements are normalized to a reference standard and are then
expressed as the logarithm to the base 10 of the value. Commonly, the
rare-earth elements are normalized to chondritic
meteorites, as these are believed to be the closest
representation of unfractionated solar system material. However, other normalizing
standards can be applied depending on the purpose of the study. Normalization
to a standard reference value, especially of a material believed to be
unfractionated, allows the observed abundances to be compared to initial
abundances of the element. Normalization also removes the pronounced ‘zig-zag’
pattern caused by the differences in abundance between even and odd atomic numbers. The
trends that are observed in "spider" diagrams are typically referred
to as "patterns", which may be diagnostic of petrological processes
that have affected the material of interest.
The rare-earth elements patterns observed in
igneous rocks are primarily a function of the chemistry of the source where the
rock came from, as well as the fractionation history the rock has
undergone.Fractionation is in turn a function of the partition coefficients of each element. Partition coefficients are
responsible for the fractionation of a trace elements (including rare-earth
elements) into the liquid phase (the melt/magma) into the solid phase (the
mineral). If an element preferentially remains in the solid phase it is termed
‘compatible’, and it preferentially partitions into the melt phase it is
described as ‘incompatible’.Each element has a different partition coefficient,
and therefore fractionates into solid and liquid phases distinctly. These
concepts are also applicable to metamorphic and sedimentary petrology.
In igneous rocks, particularly in felsic melts,
the following observations apply: anomalies in europium are dominated by the
crystallization of feldspars. Hornblende,
controls the enrichment of MREE compared to LREE and HREE. Depletion of LREE
relative to HREE may be due to the crystallization of olivine, orthopyroxene, and clinopyroxene. On the
other hand, depletion of HREE relative to LREE may be due to the presence of garnet, as
garnet preferentially incorporates HREE into its crystal structure. The
presence of zircon may
also cause a similar effect
In sedimentary rocks, rare-earth elements in clastic sediments are a
representation provenance. The rare-earth element concentrations are not
typically affected by sea and river waters, as rare-earth elements are
insoluble and thus have very low concentrations in these fluids. As a result,
when a sediment is transported, rare-earth element concentrations are
unaffected by the fluid and instead the rock retains the rare-earth element
concentration from its source.
Sea and river waters typically have low rare-earth
element concentrations. However, aqueous geochemistry is still very important.
In oceans, rare-earth elements reflect input from rivers, hydrothermal vents, and aeolian sources;
this is important in the investigation of ocean mixing and circulation.
Rare-earth elements are also useful for dating
rocks, as some radioactive isotopes display long half-lives. Of particular interest
are the 138La-138Ce, 147Sm-143Nd,
and176Lu-176Hf systems.
Scandium
or Sc (21)
Scandium, a silvery-white metal, is a non-lanthanide rare earth. It is
used in many popular consumer products, such as televisions and fluorescent or
energy-saving lamps. In industry, the primary use of scandium is to strengthen
metal compounds. The only concentrated sources of scandium currently known are
in rare minerals such as thortveitite, euxenite, and gadolinite from
Scandinavia and Madagascar.
Yttrium
or Y (39)
Yttrium is a non-lanthanide rare earth element used in many vital
applications, such as superconductors, powerful pulsed lasers, cancer treatment
drugs, rheumatoid arthritis medicines, and surgical supplies. A silvery metal,
it is also used in many popular consumer products, such as color televisions
and camera lenses.
Lanthanum
or La (57)
This silver-white metal is one of the most reactive rare earth elements.
It is used to make special optical glasses, including infrared absorbing glass,
camera and telescope lenses, and can also be used to make steel more malleable.
Other applications for lanthanum include wastewater treatment and petroleum
refining.
Cerium
or Ce (58)
Named for the Roman goddess of agriculture, Ceres, cerium is a
silvery-white metal that easily oxidizes in the air. It is the most abundant of
the rare earth elements and has many uses. For instance, cerium oxide is used
as a catalyst in catalytic converters in automotive exhaust systems to reduce
emissions, and is highly desirable for precision glass polishing. Cerium can
also be used in iron, magnesium and aluminum alloys, magnets, certain types of
electrodes, and carbon-arc lighting.
Praseodymium
or Pr (59)
This soft, silvery metal was first used to create a yellow-orange stain
for ceramics. Although still used to color certain types of glasses and
gemstones, praseodymium is primarily used in rare earth magnets. It can also be
found in applications as diverse as creating high-strength metals found in
aircraft engines and in flint for starting fires.
Neodymium
or Nd (60)
Another soft, silvery metal, neodymium is used with praseodymium to
create some of the strongest permanent magnets available. Such magnets are
found in most modern vehicles and aircraft, as well as popular consumer
electronics such as headphones, microphones and computer discs. Neodymium is
also used to make high-powered, infrared lasers for industrial and defense
applications.
Promethium
or Pm (61)
Although
the search for the element with atomic number 61 began in 1902, it was not
until 1947 that scientists conclusively produced and characterized promethium,
which is named for a character in Greek mythology. It is the only naturally
radioactive rare earth element, and virtually all promethium in the earth’s
crust has long ago decayed into other elements. Today, it is largely
artificially created, and used in watches, pacemakers, and in scientific
research.
Samarium
or Sm (62)
This silvery metal can be used in several vital ways. First, it is part
of very powerful magnets used in many transportation, defense, and commercial
technologies. Second, in conjunction with other compounds for intravenous
radiation treatment it can kill cancer cells and is used to treat lung,
prostate, breast and some forms of bone cancer. Because it is a stable neutron
absorber, samarium is used to control rods of nuclear reactors, contributing to
their safe use.
Europium
or Eu (63)
Named for the continent of Europe, europium is a hard metal used to
create visible light in compact fluorescent bulbs and in color displays.
Europium phosphors help bring bright red to color displays and helped to drive
the popularity of early generations of color television sets. Fittingly, it is
used to make the special phosphors marks on Euro notes that prevent
counterfeiting.
Gadolinium
or Gd (64)
Gadolinium has particular properties that make it especially suited for
important functions, such as shielding in nuclear reactors and neutron
radiography. It can target tumors in neuron therapy and can enhance magnetic
resonance imaging (MRI), assisting in both the treatment and diagnosis of
cancer. X-rays and bone density tests can also use gadolinium, making this rare
earth element a major contributor to modern health care solutions.
Terbium
or Tb (65)
This silvery rare earth metal is so soft it can be cut with a knife.
Terbium is often used in compact fluorescent lighting, color displays, and as
an additive to permanent rare earth magnets to allow them to function better
under higher temperatures. It can be found in fuel cells designed to operate at
elevated temperatures, in some electronic devices and in naval sonar systems.
Discovered in 1843, terbium in its alloy form has the highest magnetostriction
of any such substance, meaning it changes its shape due to magnetization more
than any other alloy. This property makes terbium a vital component of
Terfenol-D, which has many important uses in defense and commercial
technologies.
Dysprosium
or Dy (66)
Another soft, silver metal, dysprosium has one of the highest magnetic
strengths of the elements, matched only by holmium. Dysprosium is often added
to permanent rare earth magnets to help them operate more efficiently at higher
temperatures. Lasers and commercial lighting can use dysprosium, which may also
be used to create hard computer disks and other electronics that require
certain magnetic properties. Dysprosium may also be used in nuclear reactors
and modern, energy-efficient vehicles.
Holmium
or Ho (67)
Holmium was discovered in 1878 and named for the city of Stockholm.
Along with dysprosium, holmium has incredible magnetic properties. In fact,
some of the strongest artificially created magnetic fields are the result of
magnetic flux concentrators made with holmium alloys. In addition to providing
coloring to cubic zirconia and glass, holmium can be used in nuclear control
rods and microwave equipment.
Erbium
or Er (68)
Another rare earth with nuclear applications, erbium can be found in
neutron-absorbing control rods. It is a key component of high-performance fiber
optic communications systems, and can also be used to give glass and other
materials a pink color, which has both aesthetic and industrial purposes.
Erbium can also help create lasers, including some used for medical purposes.
Thulium
or Tm (69)
A silvery-gray metal, thulium is one of the least abundant rare earths.
Its isotopes are widely used as the radiation device in portable X-rays, making
thulium a highly useful material. Thulium is also a component of highly
efficient lasers with various uses in defense, medicine and meteorology.
Ytterbium
or Yb (70)
This element, named for a village in Sweden associated with its
discovery, has several important uses in health care, including in certain
cancer treatments. Ytterbium can also enhance stainless steel and be used to
monitor the effects of earthquakes and explosions on the ground.
Lutetium or Lu (71)
The last of the rare earth elements (in order of their atomic number)
has several interesting uses. For instance, lutetium isotopes can help reveal
the age of ancient items, like meteorites. It also has applications related to
petroleum refining and positron emission tomography. Experimentally, lutetium
isotopes have been used to target certain types of tumors.
Collectively, the rare earth elements contribute to vital technologies
we rely on today for safety, health and comfort. All of the rare earth elements
contribute to the advancement of modern technologies and to promising
discoveries yet to come.
Market demand for rare earth
metals and Renewable energy
By most accounts, the
green technology revolution is imminent and will be massive. We’re already
seeing the early days of a shift away from fossil fuels and towards renewables
with the rise of electric and hybrid vehicles and wind turbines increasingly
popping up across the landscape. These
technologies are poised to take over quickly. At the center of this revolution
are the raw materials needed to make these technologies function and this means
incredible opportunity for companies producing the rare earth metals neodymium
and praseodymium (NdPr).
At the 2017 International Renewable
Energy Agency (IRENA) assembly, the organization’s Director-General Adnan Z.
Amin highlighted the “phenomenal”
pace at which renewable energies are
gaining ground, highlighting the falling costs and rising capacity for
renewable energy generation. The number of electric vehicles (EVs) on the road
is steadily rising from 3.7 million in 2017 to a projected 13 million by 2020
according the International Energy Agency (IEA). Vehicle manufacturers are
scrambling to prepare for this shift, with most major manufacturers now
offering at least one electric model with plans underway for more expansive offerings.
Leading the way for this transition
is China. Under intense pressure to address the massive pollution problem
causing the ubiquitous smog problem that has plagued the nations largest
cities, the Chinese government has put significant focus on investment into
renewables. Today, more than half of the EVs on the road are driving the
streets of the most populous nation on Earth and China is home to the vast
majority of electric automakers. China also has a wind power capacity of 2,380
gigawatts, the largest of any nation on the planet.
Rare earths
and high power magnets
The technology behind
the renewable energy revolution would not be possible without neodymium, the
rare earth element used to make the most powerful industrial magnets available.
Within just about any electric motor a neodymium magnet can be found, made from
an alloy of neodymium, iron and boron.
The very specific
tetragonal crystalline structure of these magnets ensures that they magnetize
exclusively along a particular crystal axis and will not magnetize in any other
direction. This makes neodymium magnets highly resistant to demagnetization.
There’s a range of magnetic material that can be used in electric motors and
other technologies like wind turbines, but due to its resistance to
demagnetization, neodymium is greatly preferred.
Electricity generated
by turbines using NdPr magnets transforms the energy that will drive the
future. And that future will be driven by NdPr-powered electric motors. At this
point, there’s very little doubt about that. Market momentum is quickly
shifting towards these renewable technologies, a phenomenon that is being
helped along by tightening global emission standards and government policies
around the world designed to encourage investment in renewables. The bottom
line: we’re going to need a lot of NdPr.
Supply and
market demand for rare earth metals
The momentum of the
renewable energy sector has led to concerns of a supply deficit, as automakers
and other manufacturers scramble to get a hold of the materials needed to build
green technologies automakers are now
currently looking to ensure that they have long term supply agreements for the
rare earth magnet metals. Even if they are not producing EVs today, they are
now designing their models three or four years in advance of actual assembly
and these long lead times mean they need to ensure they have all the component
parts locked down well in advance.
China is the world’s
largest producer of rare earth resources, as well as the global leader in renewable
technologies. As the producer of 85 percent of global rare earth production,
one might assume that China would take this opportunity to further establish
itself as the primary global rare earth supplier. However, going forward, China
may have little interest in exporting its rare earths. Rather, the populous
country is focusing its rare earth dominance on aiding the domestic EV market,
keeping their own product within its borders as well as encouraging foreign
firms to move production to China. This is in hopes of cementing the country’s
global dominance in the EV market as EVs become the standard worldwide. This
further exacerbates rare earth supply concerns outside of China. The resulting
deficit for China’s insatiable market demand for rare earth metals could create
an extremely favorable environment for rare earth producers in China as well as
those serving the market beyond its borders.
Rare-earth element cerium is
actually the 25th most abundant element in Earth's crust, having
68 parts per million (about as common as copper). Only the highly unstable and
radioactive promethium “rare
earth" is quite scarce.
The rare-earth elements are often found together.
The longest-lived isotope of promethium has a half-life of 17.7 years, so the
element exists in nature in only negligible amounts (approximately 572 g in the
entire Earth's crust). Promethium is one of the two elements that do
not have stable (non-radioactive) isotopes and are followed by (i.e. with
higher atomic number) stable elements (the other being technetium).
During the sequential accretion of the Earth, the
dense rare-earth elements were incorporated into the deeper portions of the
planet. Early differentiation of molten material largely incorporated the
rare-earths into Mantle rocks.The high field strength and large ionic
radii of rare-earths make them incompatible with the crystal lattices of most
rock-forming minerals, so REE will undergo strong partitioning into a melt
phase if one is present. REE are chemically very similar and have
always been difficult to separate, but a gradual decrease in ionic radius from
LREE to HREE, called lanthanide contraction, can produce a broad separation between light and
heavy REE. The larger ionic radii of LREE make them generally more incompatible
than HREE in rock-forming minerals, and will partition more strongly into a
melt phase, while HREE may prefer to remain in the crystalline residue,
particularly if it contains HREE-compatible minerals like garnet.The result is
that all magma formed from partial melting will always have greater
concentrations of LREE than HREE, and individual minerals may be dominated by
either HREE or LREE, depending on which range of ionic radii best fits the
crystal lattice.
Among the anhydrous rare-earth phosphates, it is
the tetragonal mineral xenotime that
incorporates yttrium and the HREE, whereas the monoclinic monazitephase
incorporates cerium and the LREE preferentially. The smaller size of the HREE
allows greater solid solubility in the rock-forming minerals that make up
Earth's mantle, and thus yttrium and the HREE show less enrichment in Earth's
crust relative to chondritic
abundance than does cerium and the LREE. This has economic consequences: large
ore bodies of LREE are known around the world and are being exploited. Ore
bodies for HREE are more rare, smaller, and less concentrated. Most of the
current supply of HREE originates in the "ion-absorption clay" ores
of Southern China. Some versions provide concentrates containing about 65%
yttrium oxide, with the HREE being present in ratios reflecting the Oddo–Harkins rule: even-numbered REE at abundances of about 5% each,
and odd-numbered REE at abundances of about 1% each. Similar compositions are
found in xenotime or gadolinite.
Well-known minerals containing yttrium, and other
HREE, include gadolinite, xenotime, samarskite, euxenite, fergusonite,
yttrotantalite, yttrotungstite, yttrofluorite (a variety of fluorite),
thalenite, yttrialite. Small
amounts occur in zircon, which
derives its typical yellow fluorescence from some of the accompanying HREE. The
zirconium mineral eudialyte, such as
is found in southern Greenland,
contains small but potentially useful amounts of yttrium. Of the above yttrium
minerals, most played a part in providing research quantities of lanthanides
during the discovery days. Xenotime is
occasionally recovered as a byproduct of heavy-sand processing, but is not as
abundant as the similarly recovered monazite (which
typically contains a few percent of yttrium). Uranium ores from Ontario have
occasionally yielded yttrium as a byproduct.
Well-known minerals containing cerium, and other
LREE, include bastnäsite, monazite, allanite, loparite, ancylite, parisite, lanthanite,
chevkinite, cerite, stillwellite,
britholite, fluocerite, and
cerianite. Monazite (marine sands from Brazil, India, or Australia; rock
from South Africa), bastnäsite (from Mountain Pass, California, or several localities in China), and loparite (Kola Peninsula, Russia) have
been the principal ores of cerium and the light lanthanides.
Enriched deposits of rare-earth elements at the
surface of the Earth, carbonatites and pegmatites, are
related to alkaline plutonism, an uncommon kind of magmatism that occurs in
tectonic settings where there is rifting or that are near subduction zones.In
a rift setting, the alkaline magma is produced by very small degrees of partial
melting (<1 garnet="" in="" of="" peridotite="" span="" the="" upper="">mantle (200 to
600 km depth).This melt becomes enriched in incompatible elements, like the
rare-earth elements, by leaching them out of the crystalline residue. The
resultant magma rises as a diapir, or diatreme, along pre-existing fractures,
and can be emplaced deep in the crust, or
erupted at the surface. Typical REE enriched deposits types forming in rift
settings are carbonatites, and A- and M-Type granitoids. Near
subduction zones, partial melting of the subducting plate within the asthenosphere (80 to
200 km depth) produces a volatile-rich magma (high concentrations of CO2
and water), with high concentrations of alkaline elements, and high element
mobility that the rare-earths are strongly partitioned into.This melt may also
rise along pre-existing fractures, and be emplaced in the crust above the
subducting slab or erupted at the surface. REE enriched deposits forming from
these melts are typically S-Type granitoids.
Alkaline magmas enriched with rare-earth elements
include carbonatites, peralkaline granites (pegmatites), and nepheline syenite.Carbonatites
crystallize from CO2-rich fluids, which can be produced by partial
melting of hydrous-carbonated lherzolite to
produce a CO2-rich primary magma, by fractional crystallization of
an alkaline primary magma, or by separation of a CO2-rich immiscible
liquid from.These liquids are most commonly forming in association with very
deep Precambrian Cratons, like
the ones found in Africa and the Canadian Shield. Ferrocarbonatites
are the most common type of carbonatite to be enriched in REE, and are often
emplaced as late-stage, brecciated pipes at the core of igneous complexes; they
consist of fine-grained calcite and hematite, sometimes with significant
concentrations of ankerite and minor concentrations of siderite. Large
carbonatite deposits enriched in rare-earth elements include Mount Weld in
Australia, Thor Lake in Canada, Zandkopsdrift in South Africa, and Mountain
Pass in the USA. Peralkaline granites (A-Type
granitoids) have very high concentrations of alkaline elements and very low
concentrations of phosphorus; they are deposited at moderate depths in
extensional zones, often as igneous ring complexes, or as pipes, massive
bodies, and lenses.These fluids have very low viscosities and high element
mobility, which allows for crystallization of large grains, despite a
relatively short crystallization time upon emplacement; their large grain size
is why these deposits are commonly referred to as pegmatites. Economically
viable pegmatites are divided into Lithium-Cesium-Tantalum (LCT) and
Niobium-Yttrium-Fluorine (NYF) types; NYF types are enriched in rare-earth
minerals. Examples of rare-earth pegmatite deposits include Strange Lake in
Canada, and Khaladean-Buregtey in Mongolia. Nepheline syenite (M-Type
granitoids) deposits are 90% feldspar and feldspathoid minerals, and are
deposited in small, circular massifs. They contain high concentrations of rare-earth-bearing accessory minerals For the most part these
deposits are small but important examples include Illimaussaq-Kvanefeld in
Greenland, and Lovozera in Russia.
Rare earths players
Medallion Resources is one of the
companies looking to help fill the rare earth supply void in North America. The
company is focused on acquiring discarded or stockpiled monazite via long-term
supply agreements with mineral sands mines and shipping these materials to a
North American processing plant to extract a rare earth chemical concentrate
product. Medallion has developed a unique method for turning that waste product
into useful rare earth material at low cost. The company hopes this will put
them on the path to becoming a major player in the nascent rare earths market.
In China, the industry is dominated
by a mix of private firms, local state owned firms and national state firms.
Major Chinese rare earth companies include Inner Mongolia Baotou Steel
Rare-Earth Hi-Tech Company, China Minmetals Corporation, Aluminum Corporation
of China Limited and China Non-Ferrous Metal Mining.
Coming in at a very distant second,
the largest rare earth producing nation after China is Australia. Production in
the land down under has been rising steadily over the past few years, reaching
20,000 MT in 2017. Australian company Lynas (ASX:LYC)
operates Australia’s Mount Weld mine, one of the largest rare earth producers
on the planet. Australian company Northern Minerals (ASX:NTU) added to the country’s production in 2017 when they opened Australia’s first heavy
rare earths mine.
Rare-earth elements can also be enriched in
deposits by secondary alteration either by interactions with hydrothermal
fluids or meteoric water or by erosion and transport of resistate REE-bearing
minerals. Argillization of primary minerals enriches insoluble elements by
leaching out silica and other soluble elements, recrystallizing feldspar into
clay minerals such kaolinite, halloysite and montmorillonite. In tropical
regions where precipitation is high, weathering forms a thick argillized
regolith, this process is called supergene enrichment and produces laterite deposits;
heavy rare-earth elements are incorporated into the residual clay by
absorption. This kind of deposit is only mined for REE in Southern China, where
the majority of global heavy rare-earth element production occurs.
REE-laterites do form elsewhere, including over the carbonatite at Mount Weld
in Australia. REE may also by extracted from placer deposits if the sedimentary
parent lithology contained REE-bearing, heavy resistate minerals.
In 2011, Yasuhiro Kato, a geologist at the University of Tokyo who led a study of Pacific Ocean seabed mud,
published results indicating the mud could hold rich concentrations of
rare-earth minerals. The deposits, studied at 78 sites, came from "[h]ot
plumes from hydrothermal vents pull[ing] these materials out of seawater and
deposit[ing] them on the seafloor, bit by bit, over tens of millions of years.
One square patch of metal-rich mud 2.3 kilometers wide might contain enough
rare earths to meet most of the global demand for a year, Japanese geologists
report July 3 in Nature Geoscience."
"I believe that rare earth
resources undersea are much more promising than on-land resources," said
Kato. "Concentrations of rare earths were comparable to those found in
clays mined in China. Some deposits contained twice as much heavy rare earths
such as dysprosium, a component of magnets in hybrid car motors.
Global
rare-earth production
Until 1948, most of the world's rare earths were
sourced from placer sand deposits in India and Brazil. Through
the 1950s, South Africa was the world's rare-earth source, from a monazite-rich
reef at the Steenkampskraal mine in Western Cape Province.
Through the 1960s until the 1980s, the Mountain Pass rare earth mine in California was the leading producer. Today, the
Indian and South African deposits still produce some rare-earth concentrates,
but they are dwarfed by the scale of Chinese production. In 2017, China
produced 81% of the world's rare-earth supply, mostly in Mongolia, although it
had only 36.7% of reserves. Australia was the second and only other major
producer with 15% of world production. All of the world's heavy rare earths
(such as dysprosium) come from Chinese rare-earth sources such as the polymetallic
Bayan Obo deposit.
The Browns Range mine, located 160 km south east of Halls Creek in
northern Western Australia, is currently under development and is positioned
to become the first significant dysprosium producer outside of China.
Increased demand has strained supply, and there is
growing concern that the world may soon face a shortage of the rare earths. In
several years from 2009 worldwide demand for rare-earth elements is expected to
exceed supply by 40,000 tonnes annually unless major new sources are developed.
In 2013, it was stated that the demand for REEs would increase due to the
dependence of the EU on these elements, the fact that rare earth elements
cannot be substituted by other elements and that REEs have a low recycling
rate. Furthermore, due to the increased demand and low supply, future prices
are expected to increase and there is a chance that countries other than China
will open REE mines.REE is increasing in demand due to the fact that they are
essential for new and innovative technology that is being created. These new
products that need REEs to be produced are high technology equipment such as
smart phones, digital cameras, computer parts, etc. In addition, these elements
are more prevalent is production in the renewable energy technology industry, military
equipment industry, glass making and metallurgy
Conclusions
The world-wide shift
to renewable technology is well underway and the effects will be seen more and
more across global commerce as the revolution gains steam. In the global
resource industry this means a huge boom for the market demand for rare earth
metals that are absolutely vital to the adoption of these technologies. As the
world’s largest rare earth producing country keeps a tight grasp on its own
production, the rest of the world will provide a rare and massive opportunity
for non-Chinese rare earth companies.
Rare
Earth Metals Ban : May, 29, 2019:
Beijing is "seriously considering" restricting
exports to the United States of rare earths, 17 chemical elements used in
high-tech consumer electronics and military equipment, the editor in chief of
China's Global Times said on Tuesday. Rising trade tensions have led to
concerns that Beijing will use its dominant position as a supplier of rare
earths for leverage in the trade war between the United States and China. A
senior official from China's National Development and Reform Commission told the
Xinhua news agency on Tuesday that Beijing will give domestic demand for rare
earths priority, but will meet reasonable demand from other countries
