
The Ranger Uranium Mine in
Australia.
Uranium mining is the process of extraction of
uranium ore from the
ground. As uranium ore is mostly present at relatively low
concentrations, most uranium mining is very volume-intensive, and
thus tends to be undertaken as
open-pit
mining. It is also undertaken in only a small number of
countries of the world, as the resource is rare.
The
worldwide production of uranium in 2008 amounted to 43,853 tonnes, of which 20% was mined in Canada
.
Canada,
Kazakhstan
, and Australia are the top
three producers and together account for 59% of world uranium
production. Other important uranium producing countries
in excess of 1000 tonnes per year are Namibia
, Russia
, Niger
, Uzbekistan
, and the United States
.
A prominent use of uranium from mining is as fuel for
nuclear power plants. As of 2008, known
uranium ore resources which can be mined at about current costs are
estimated to be sufficient to produce fuel for about a century,
based on current consumption rates.
After mining uranium ores, they are normally processed by grinding
the ore materials to a uniform particle size and then treating the
ore to extract the uranium by chemical leaching. The milling
process commonly yields dry powder-form material consisting of
natural uranium, "
yellowcake," which is
sold on the uranium market as U
3O
8.
History
Uranium minerals were noticed by miners for a long time prior to
the discovery of uranium in 1789.
The uranium mineral pitchblende, also known as uraninite, was
reported from the Erzgebirge Ore Mountains
, Saxony
, as early as
1565. Other early reports of pitchblende date from
1727 in Joachimsthal
and 1763 in Schwarzwald
.
In the
early 1800s, uranium ore was recovered as a by-product of mining in
Saxony
, Bohemia, and Cornwall
. The first deliberate mining of radioactive ores took place in Jáchymov
, also known by its German name Joachimsthal
, a silver-mining city in what is now the Czech Republic
. Marie Curie used
pitchblende ore from Jáchymov to isolate
the element
radium, a
decay product of uranium; her death was from
aplastic anemia, almost certainly
due to exposure to
radioactivity.
Until World War II uranium mining was done primarily for the radium
content. Sources for
radium, contained in the
uranium ore, were sought for use as
luminous paint for watch dials and other
instruments, as well as for health-related applications, some of
which in retrospect were incredibly unhealthy. The byproduct
uranium was used mostly as a yellow
pigment.
In the
United
States
, the first radium/uranium ore was discovered in
1871 in gold mines near Central City,
Colorado
. This district produced about 50 tons
of high grade ore between 1871 and 1895.
However, most American
uranium ore before World War II came from vanadium deposits on the Colorado Plateau of Utah
and Colorado
.
In
Cornwall
, the South Terras Mine near St. Stephen opened for uranium production in
1873, and produced about 175 tons of ore before 1900.
Other
early uranium mining occurred in Autunois in France's Massif
Central
, Oberpfalz in Bavaria
, and Billingen
in Sweden
.
The
Shinkolobwe
deposit in Katanga
, Belgian Congo now
Shaba
Province
, Zaire
was
discovered in 1913, and exploited by the Union Minière du Haut
Katanga. Other important early deposits include
Port Radium, near Great Bear
Lake
, Canada discovered in 1931, along with Beira Province, Portugal; Tyuya Muyun, Uzbekistan
, and Radium
Hill
, Australia.
Because of the need for the uranium for bomb research during World
War II, the
Manhattan Project used
a variety of sources for the element. The Manhattan Project
initially purchased uranium ore from the
Belgian Congo, through the
Union Minière du Haut
Katanga. Later the project contracted with
vanadium mining companies in the American
Southwest. Purchases were also made from the
Eldorado Mining and
Refining Limited company in Canada. This company had large
stocks of uranium as waste from its radium refining
activities.
American uranium ores mined in Colorado were mixed ores of vanadium
and uranium, but because of wartime secrecy the Manhattan Project
would only publicly admit to purchasing the vanadium, and did not
pay the uranium miners for the uranium content. In a much later
lawsuit, many miners were able to reclaim lost profits from the
U.S. government. American ores had much lower uranium
concentrations than the ore from the Belgian Congo, but they were
pursued vigorously to ensure nuclear self-sufficiency.
Similar
efforts were undertaken in the Soviet Union
, which did not have native stocks of uranium when
it started developing its own atomic weapons program.
Intensive exploration for uranium started after the end of World
War II as a result of the military and civilian demand for uranium.
There were three separate periods of uranium exploration or
"booms." These were from 1956 to 1960, 1967 to 1971, and from 1976
to 1982 .
In the 20th century the United States was the world's largest
uranium producer. Grants Uranium District in northwestern New
Mexico was the largest United States uranium producer. The Gas
Hills Uranium District, was the second largest uranium producer.
The famous Lucky Mc Mine is located in the Gas Hills near Riverton,
Wyoming. Canada has since surpassed the United States as the
cumulative largest producer in the world.
By territory

2007 uranium mining, by
nationality.
Oceania
Australia
Production in Australia rose significantly to 10,115 tU3O8 (22.3
million pounds) in 2007 from 19.7 million pounds in 2006, securing
its position as the second largest uranium producing country, most
of the production gain coming from increased operational
performance and an increase in the grade of the ore mined.
Australia has the world's largest uranium reserves - 24 percent of
the planet's known reserves. The majority of these reserves are
located in South Australia with other important deposits in
Queensland, Western Australia and the Northern Territory.
Almost
all the uranium is exported under strict International Atomic Energy
Agency
safeguards to satisfy the Australian people and
government that none of the uranium is used in nuclear weapons. Australian uranium
is used strictly for electricity production.
The
Olympic Dam operation run by BHP Billiton in South Australia
is combined with mining of copper, gold, and silver, and has reserves of global
significance. There are currently three operating uranium
mines in Australia, and several more have been proposed. The
expansion of Australia's uranium mines is supported by the Federal
Australian Labor Party (ALP) Government headed by Prime Minister
Kevin Rudd. The ALP abandoned its long-standing and controversial
"no new uranium mines" policy in April 2007.
One of the more
controversial proposals was Jabiluka
, to be built surrounded by the World Heritage listed Kakadu
National Park
. The existing Ranger Uranium Mine
is also surrounded by the National Park as the mine
area was not included in the original listing of the
Park.
Uranium mining and export and related nuclear issues have often
been the subject of public debate, and the
anti-nuclear movement in
Australia has a long history.
North America
Canada
Canada is
the largest exporter of uranium ore, with the largest mines located
in Athabasca Basin in northern
Saskatchewan
.
Canada's
first uranium discovery was in the Alona Bay area,
south of Lake Superior Provincial Park
in Ontario, by Dr. John Le Conte in 1847.
But the Canadian uranium industry really began with the 1932
discovery of
pitchblende at
Port Radium, Northwest
Territories. The deposit was mined from 1933 to 1940, for
radium,
silver,
copper, and
cobalt. The
mine shut down in 1940, but was reopened in 1942 by
Eldorado Mining and
Refining Limited to supply uranium to the
Manhattan Project. The Canadian government
expropriated the Port Radium mine and banned private claimstaking
and mining of radioactive minerals.
In 1947 the government lifted the ban on private uranium mining,
and the industry boomed through the 1950s, spurred by high prices
due to the nuclear weapons programs. Production peaked in 1959,
when 23 mines in five different districts made uranium Canada's
number-one export. That same year, however, Great Britain and the
United States announced their intention to halt uranium purchases
in 1963. By 1963, seven mines were left operating, a number that
shrank to only three in 1972.
A price rise caused uranium to boom again in 1975 and 2005.
Despite overall country production falling some 4% to 11,158 t
(24.6 million pounds) U
3O
8, Canada is again
the world's largest uranium producing country, accounting for 23%
of world production in 2007. Production was led by
Cameco's majority-owned McArthur River/Key Lake JV
which yielded a total of 8,482 t (18.7 million pounds)
U
3O
8 in 2007, which was the same level as in
2006.
Cameco's 100%-owned Rabbit Lake
mine
produced 1,814 t (4.0 million pounds)
U3O8, which was a 21.7% decline from
production of 5.1 million pounds (2,300 t) in 2006.
Northwest Territories
Ontario
In 1948, prospector Robert Campbell discovered
pitchblende at
Theano Point, in
the area of Alona Bay, Ontario, and staked 30 claims. By November
1948 a rush had begun, and in the next three years, 5,000 claims
would be staked in the area.
A shaft and headframe were constructed, but
abandoned before operations could begin; the mine proved
unprofitable after uranium discoveries at Elliot Lake
, Ontario.
The
uranium-bearing pegmatite of Bancroft,
Ontario
began mining in 1952.
Uranium
was discovered at Blind River
-Elliot
Lake
area in 1949, and production began in 1955.
The
deposits are in Precambrian quartz-pebble conglomerate, similar to uranium
deposits in Brazil
and
South Africa.
Saskatchewan

size
Pitchblende veins were discovered near
Beaverlodge Lake, Saskatchewan
in 1935, and uranium mining started in
1953.
Today the
Athabasca Basin in northern Saskatchewan
hosts the largest high-grade uranium mines and
deposits. Cameco, the
world's largest low-cost uranium producer, which accounts for 18%
of the world's uranium production, operates three mines and one
dedicated mill in the region.
Among the major mines are Cameco's flagship
McArthur
River mine
, the developing Cigar Lake mine
, the Rabbit Lake mine
and mill complex, and the world's largest uranium
mill at Key
Lake
. French-owned uranium syndicate
Areva also operates the McClean Lake mill. Most of
these mines are joint ventures between Cameco, Areva, and various
other joint venture shareholders. Future mines currently in early
development stages include Areva's Midwest Project (near McClean
Lake), and Cameco's Millennium Project (near Key Lake). As of 2007,
with uranium spot market prices well over the $100 USD/lb mark,
Saskatchewan has become a hotbed of uranium exploration, with many
junior exploration companies rushing to explore the highly valuable
Athabasca basin.
United States
Most uranium ore in the United States comes from deposits in
sandstone, which tend to be of lower grade
than those of Australia and Canada. Because of the lower grade,
many uranium deposits in the United States became uneconomic when
the price of uranium declined sharply in the 1980s.
Regular
production of uranium-bearing ore in the United States began in
1898 with the mining of carnotite-bearing
sandstones of the Colorado Plateau
in Colorado
and Utah
, for their
vanadium content. The discovery of
radium by
Marie
Curie, also in 1898, soon made the ore also valuable for
radium. Uranium was a by-product. By 1913, the
Colorado Plateau uranium-vanadium province
was supplying about half the world supply of radium.
Production declined
sharply after 1923, when low-cost competition from radium from the
Belgian Congo and vanadium from Peru
made the
Colorado Plateau ores
uneconomic.
Mining revived in the 1930s with higher prices for vanadium.
American uranium ores were in very high demand by the
Manhattan Project during World War II,
although the mining companies did not know that the by-product
uranium was suddenly valuable. The late 1940s and early 1950s saw a
boom in uranium mining in the western US, spurred by the fortunes
made by prospectors such as
Charlie
Steen.
Uranium mining declined with the last
open
pit mine (Shirley Basin, Wyoming) shutting down in 1992. United
States production occurred in the following states (in descending
order): New Mexico, Wyoming, Colorado, Utah, Texas, Arizona,
Florida, Washington, and South Dakota. The collapse of uranium
prices caused all conventional mining to cease by 1992.
In-situ leach mining has continued primarily
in Wyoming and adjacent Nebraska as well has recently restarted in
Texas. Rising uranium prices since 2003 have increased interest in
uranium mining in the United States.
Arizona
On
Wednesday 25 June 2008 the House Natural Resources Committee voted
overwhelmingly to enact emergency protections from uranium mining
for of public lands around Grand Canyon
National Park. This will mean the Secretary
of the Interior has an obligation to protect public lands near the
Grand Canyon from uranium extraction for three years.
The Center for
Biological Diversity, Sierra Club,
and the Grand Canyon Trust recently won a court order against
the Kaibab
National Forest
stopping uranium drilling near the national park
until a thorough environmental analysis is conducted..
The Grand Canyon Watersheds Protection Act has been proposed. This
is a bill that would permanently ban uranium mining in the area.The
impacts of uranium development have raised concerns of scientists
and government officials alike. Due to increasing demand, uranium
projects have been on the increaseposing a threat to water, public
health, and fragile desert ecosystems.
CIS
Kazakhstan
Kazakhstan
produced some 7847 tU3O8 (17.3 million pounds in
2007), much more than in 2006. Kazatomprom's four 100%-owned ISR mining groups
(LLP Kazatomprom) combined produced half of the total output.
Russia
The
World Nuclear Association
states that Russia has known uranium
deposits of 500,000 tonnes and plans to mine 11,000 to 12,000
tonnes per year from deposits in the South Urals, Western Siberia,
and Siberia east of Lake
Baikal
, by 2010.
The Russian nuclear industry has been undergoing an overall
restructuring process during 2007. The production was high as
almost 4 000 tU3O8 (8.8 million pounds) from three operating mines
in 2007. Atomredmetzoloto reported that the Priargunsky mine
yielded 7.8 million pounds in 2007, a slight decline from the 8.2
million pounds reported by
TVEL in 2006. At the
Dalur (Dolmatovskoye) and Khiagda ISR mines, production of 910 000
pounds and 68 000 pounds, respectively, was reached in 2007. Both
ISR projects are expected to increase production steadily through
2015.
Ukraine
Ukraine's
VostGOK produced almost 1000 tU3O8 (2.2 million pounds) from the
Zhovti
Vody
mill in 2007, which was similar to the 2.1 million
pounds produced in 2006.
Uzbekistan
In
Uzbekistan
, the Navoi Mining &
Metallurgy Combinat reportedly produced 2,721 tonnes U3O8 or
tU3O8 (6 million pounds) from its Nurabad,
Uchkuduk
and Zafarabad
in-situ recovery
facilities.
Europe
European uranium mining supplied just below 3% of the total
EU needs,
coming from the Czech Republic and Romania (a total of 526 tU).
Production in the Rožňa mine was to be terminated in 2008, but the
Czech Government decided in May 2007 to continue mining and
extended the lifetime without time limit as long as it remains
profitable.
Bulgaria
Bulgaria shut down its facilities for environmental reasons in
1992; terrains were recultivated but recently, there has been
certaing interest in resuming activities. Industrial mining first
started in 1938 and was resumed after 1944 by a joint
Soviet-Bulgarian mining company, reorganized in 1956 into the Redki
Metali (Rare Metals) government-owned concern.
At its peak, it had
13,000 employees, operated 48 uranium mines and two enrichment
plants at Buhovo outside Sofia
and
Eleshnitsa near Bansko
.
Yearly
production was estimated at 645 t that met about 55% of the needs
of Kozloduy
Nuclear Power Plant
, which had six reactors with a total output of over
3600 MWe at its peak. [281358]
Czech Republic
The Czech Republic is the birthplace of industrial scale uranium
mining.
Uranium mining at Jáchymov
(at that time named Joachimsthal and belonging to
Austria-Hungary) started in the 1890s on an industrial scale, after
the silver and cobalt production of the deposit went down.
Uranium was first used to produce mainly yellow colours for glass
and porcelain manufacture. After the Curies in France discovered
the Polonium and Radium in tailings from Jáchymov, the town became
the first place in the world for commercial radium production from
uranium ore. Radioactive water from the mines was also used to set
up a health resort still exisiting today for radon-treatments.
Pre-Cold War production is estimated to be around 1,000 t of
uranium. From 1947 on the Czech Republic started producing uranium
for the Soviet Union.
Early mining sites like Jáchymov, Horní
Slavkov
and Příbram
became infamously known as parts of the "Czech
Gulag". In the whole, the Czech Republic produced 110.000 t
of uranium to 1992 from 64 uranium deposits. The largest deposit
Příbram (vein style) produced about 50.000 t of uranium and was
mined to a depth of over 1,800 m.
Today,
the Rožná
underground facility 55 km northwest of Brno
is
Europe's only operating uranium mine, continuously operating since
1957. It produces about 300 t of uranium annualy.
Since
2007, the Australian company Uran Ltd. is
interested to participate in the operations at Rožná, as well as
seeking permits with the Czech Ministry of Trade and Resources to
open mines in the Czech Republic at other known locations, like
Brzkov
, Jamné
, Polná
and
Věžnice, through its Czech partner
Timex Zdice and since 2008 through its subsidiary Urania
Mining.
Estonia
During
1946–1952, the Dictyonema argillite (claystone) was
mined and used for uranium production in Sillamäe
.
Finland
In
Uusimaa
, Karelia
and Lapland
in Finland, presently (2009) uranium deposits are
investigated
Germany
Search
for uranium ore intensified during the cold war, but only in
East
Germany
was an extensive uranium mining industry
established. Uranium was mined from 1947 to 1990 from
mines in Saxony
and Thuringia
by the SDAG
Wismut. All the uranium mines were closed after the
German reunification for
economic and environmental reasons. Total production in East
Germany was 230.400 t of uranium making it the third largest
producer in history behind the USA and Canada.
A minor production
still takes place at the Königstein mine southeast of Dresden
from cleaning of mine water. This production
has been 38 t of uranium in 2007.
Hungary
In
Hungary uranium mining began in the 1950s around Pécs
to supply the country's first atomic
plant
in Paks
.
After the fall of communism, uranium mining was gradually given up
because of the high production costs. That caused serious economic
problems and a rise of unemployment in Pécs.
Romania
Romania
produced in 2008 around 250 tonnes of uranium., see SovRoms,
Crucea - Botusana mine and
Băiţa mine.
Slovakia
A mine is
proposed for near the towns of Jahodná
and Košice
.
Sweden
In Sweden, uranium production took place at Ranstadsverket between
1965 and 1969 by mining of alum shale (kind of
oil shale) deposits. The goal was to make Sweden
self-supplying with uranium. The high operating costs of the pilot
plant (
heap leaching) due to the low
concentration of uranium in the shale and the, at that time,
availability of comparatively cheap uranium on the world market,
caused the mine to be closed, although a much cheaper and more
efficient leaching process, using sulfur-consuming bacteria, had by
then been developed. Since 2005 there have been investigations on
opening new uranium mines in Sweden.
United Kingdom
The South Terras Mine in Cornwall was mined for uranium from 1873
to 1903.
Substantial uranium deposits were found on
Orkney
in the
1970s, When Margaret Thatcher
proposed a uranium mine on Orkney a campaign followed which
successfully argued that uranium mining would mean irreversible
environmental, social and psychological damage.
Africa
Namibia
Namibia
produces
uranium at Rossing
deposit, where an igneous
deposit is mined from one of the world's largest open pit mines. The mine is owned by
a subsidiary of the
Rio Tinto Group.
The Langer Heinrich calcrete uranium deposit was discovered in 1973
and the open pit mine was officially opened in 2007.
Niger
Niger is Africa's leading uranium-producing nation.
Uranium is produced
from mines at Arlit
owned by
Areva NC.
In 2007, production in Niger had a total output of 3720 tonnes
U
3O
8 (8.2 million pounds) coming mainly from
the
Akouta (
Cominak)
and the Arlit (
Somair) mines.
Niger's uranium came to world attention before the US invasion of
Iraq, when it was asserted that Iraq had attempted to buy uranium
from Niger (see
Niger
uranium forgeries).
South Africa
South
Africa produces uranium from deposits in Precambrian quartz-pebble
conglomerate of the Witwatersrand Basin, at Brakpan
and Krugersdorp, Gauteng
.
Asia
China
China mined in 2007 636 tonnes of U3O8, a decrease of 17% of its
production in 2006.
India
In
Nalgonda District, the Rajiv Gandhi Tiger Reserve (the
only tiger project in Andhra
Pradesh
) has been forced to surrender over 1,000 sq.
kilometres to uranium mining following a directive from the
Central
Ministry of Environment and Forests.
In 2007, India was able to extract 229 tonnes of U3O8 from its
soil.
Jordan
Jordan, the only Middle East country with confirmed uranium, is
estimated to have around 140,000 tonnes in its uranium reserves
plus a further 59,000 tonnes in phosphate deposits. Although no
uranium has been mined yet, it was announced in 2008 that the
Jordanian Government signed an agreement with the French Company
AREVA to explore for uranium. This will
benefit them on building a future nuclear plant in Jordan.
Exploration
Uranium prospecting is similar to other forms of mineral
exploration with the exception of some specialized instruments for
detecting the presence of radioactive isotopes.
The
Geiger counter was the original
radiation detector, recording the total count rate from all energy
levels of radiation. Ionization chambers and Geiger counters were
first adapted for field use in the 1930s.
The first
transportable Geiger–Müller counter (weighing 25 kg) was
constructed at the University of British
Columbia
in 1932. H.V. Ellsworth of the GSC built a
lighter weight, more practical unit in 1934. Subsequent models were
the principal instruments used for uranium prospecting for many
years, until geiger counters were replaced by
scintillation counters.
The use of
airborne detectors to
prospect for radioactive minerals was first proposed by G.C.
Ridland, a geophysicist working at
Port
Radium in 1943. In 1947, the earliest recorded trial of
airborne
radiation detector (ionization
chambers and Geiger counters) was conducted by
Eldorado Mining and
Refining Limited. (a Canadian Crown Corporation since sold to
become
Cameco Corporation).
The first
patent for a portable gamma-ray spectrometer was filed by Professors Pringle,
Roulston & Brownell of the University of Manitoba
in 1949, the same year as they tested the first
portable scintillation counter
on the ground and in the air in northern Saskatchewan
.
Airborne gamma-ray spectrometry is now the accepted leading
technique for uranium prospecting with worldwide applications for
geological mapping, mineral exploration & environmental
monitoring.
A deposit of uranium, discovered by geophysical techniques, is
evaluated and sampled to determine the amounts of uranium materials
that are extractable at specified costs from the deposit. Uranium
reserves are the amounts of ore that are estimated to be
recoverable at stated costs.
Types of uranium deposits
Many different types of uranium deposits have been discovered and
mined.
Uranium deposits in sedimentary rock
Uranium deposits in sedimentary rocks include those in sandstone
(in Canada and the
western
US),
Precambrian unconformities (in Canada),
phosphate,
Precambrian
quartz-pebble
conglomerate, collapse breccia pipes
(see
Arizona
Breccia Pipe Uranium Mineralization),and
calcrete.
Sandstone uranium deposits are generally of two types.
Roll-front type deposits occur at the boundary
between the up dip and oxidized part of a sandstone body and the
deeper down dip reduced part of a sandstone body.
Peneconcordant sandstone uranium deposits, also
called
Colorado
Plateau-type deposits, most often occur within
generally oxidized sandstone bodies, often in localized reduced
zones, such as in association with carbonized wood in the
sandstone.
Precambrian quartz-pebble
conglomerate-type uranium deposits
occur only in rocks older than two billion years old. The
conglomerates also contain pyrite.
These deposits have been mined in the
Blind
River
-Elliot
Lake
district of Ontario, Canada, and from the
gold-bearing Witwatersrand
conglomerates of South
Africa.
Igneous or hydrothermal uranium deposits
Hydrothermal uranium deposits encompass the vein-type uranium ores.
Igneous
deposits include nepheline syenite
intrusives at Ilimaussaq, Greenland
; the disseminated uranium deposit at Rossing
, Namibia; and uranium-bearing pegmatites. Disseminated deposits are also
found in the states of Washington and Alaska in the US.
Mining techniques
As with other types of
hard rock mining there are
several methods of extraction. The main methods of mining are
box cut mining,
open pit mining and
in situ leaching
(ISL).
Open pit
In
open pit mining,
overburden is removed by drilling and blasting to
expose the ore body, which is then mined by blasting and excavation
using loaders and dump trucks. Workers spend much time in enclosed
cabins thus limiting exposure to radiation. Water is extensively
used to suppress airborne dust levels.
Underground uranium mining
If the uranium is too far below the surface for open pit mining, an
underground mine might be used with tunnels and shafts dug to
access and remove uranium
ore. There is less
waste material removed from underground mines than open pit mines,
however this type of mining exposes underground workers to the
highest levels of radon gas.
Underground uranium mining is in principle no different to any
other
hard rock
mining and other ores are often mined in association (eg
copper,
gold,
silver). Once the ore body has been identified a
shaft is sunk in the vicinity of the ore veins, and crosscuts are
driven horizontally to the veins at various levels, usually every
100 to 150 metres. Similar tunnels, known as drifts, are driven
along the ore veins from the crosscut. To extract the ore, the next
step is to drive tunnels, known as raises when driven upwards and
winzes when driven downwards through the deposit from level to
level. Raises are subsequently used to develop the stopes where the
ore is mined from the veins.
The stope, which is the workshop of the mine, is the excavation
from which the ore is extracted. Two methods of stope mining are
commonly used. In the "cut and fill" or open stoping method, the
space remaining following removal of ore after blasting is filled
with waste rock and cement. In the "shrinkage" method, only
sufficient broken ore is removed via the chutes below to allow
miners working from the top of the pile to drill and blast the next
layer to be broken off, eventually leaving a large hole. Another
method, known as room and pillar, is used for thinner, flatter ore
bodies. In this method the ore body is first divided into blocks by
intersecting drives, removing ore while so doing, and then
systematically removing the blocks, leaving enough ore for roof
support.
Heap leaching
Waste rock is produced during open pit mining when
overburden is removed, and during underground
mining when driving tunnels through non-ore zones.
Piles of these
tailings often contain
elevated concentrations of
radioisotopes compared to normal rock. Other
waste piles consist of ore with too low a grade for processing. The
difference between waste rock and ore depends on technical and
economic feasibility criteria, principally market price for ore.
All these piles threaten people and the environment after shut down
of the mine due to their release of
radon gas
and seepage water containing
radioactive
and toxic materials.
In some cases uranium has been removed from this low-grade ore by
heap leaching. This may be done if uranium content is too low for
the ore to be economically processed in a uranium mill. The
leaching liquid (often
sulfuric acid)
is introduced on the top of the pile and percolates down until it
reaches a liner below the pile, where it is caught and pumped to a
processing plant. Due to the potential for extreme damage to the
surrounding environment, this practice is no longer in use.
Heap leaching using carbonate is seen as an environmentally
responsible way to extract uranium because the only leaching
reagent is sodium bicarbonate (baking soda) and is currently being
tested for use at Ranger uranium in the Northern Territory of
Australia, at Trekkopje in Namibia, at Wiluna in Western Australia,
and at Letlhakane in Botswana.
In-situ leaching
In-situ leaching (ISL), sometimes
referred to as
in-situ recovery (ISR) or
solution
mining, is performed by pumping liquids (weak
acid or weak
alkaline depending
on the
calcium concentration in the ore)
down through injection wells placed on one side of the deposit of
uranium, through the deposit, and up through recovery wells on the
opposing side of the deposit - recovering ore by
leaching. ISL is also used on other types
of metal extraction such as
copper. ISL is
often cost-effective because it avoids excavation costs, and may be
implemented more quickly than conventional mining. However, it is
not suitable to all uranium deposits, as the host rock must be
permeable to the liquids (as is often the case in
sandstone), making it possible to contaminate
nearby aquifers with leaching chemicals. Evironmental impact
studies are performed when evaluating ISL, because
ground water can be affected.
In-situ leaching is the only type of
uranium mining currently being done in the United States
(2006).
Recovery from seawater
The uranium concentration of sea water is low, approximately
3.3 mg per
cubic meter of seawater
(3.3 ppb). But the quantity of this resource is gigantic and
some scientists believe this resource is practically limitless with
respect to world-wide demand. That is to say, if even a portion of
the uranium in seawater could be used the entire world's nuclear
power generation fuel could be provided over a long time period.
Some anti-nuclear proponents claim this statistic is exaggerated.
Although research and development for recovery of this
low-concentration element by inorganic adsorbents such as
titanium oxide compounds, has occurred since
the 1960s in the United Kingdom, France, Germany, and Japan, this
research was halted due to low recovery efficiency.
At the Takasaki Radiation Chemistry Research Establishment of the
Japan Atomic Energy Research Institute (JAERI Takasaki Research
Establishment), research and development has continued culminating
in the production of adsorbent by irradiation of polymer fiber.
Adsorbents have been synthesized that have a functional group
(
amidoxime group) that selectively
adsorbs heavy metals, and the performance of such adsorbents has
been improved. Uranium adsorption capacity of the
polymer fiber adsorbent is high,
approximately tenfold greater in comparison to the conventional
titanium oxide adsorbent.
One method of extracting uranium from seawater is using a
uranium-specific nonwoven fabric as an absorbent. The total amount
of uranium recovered from three collection boxes containing
350 kg of fabric was >1 kg of
yellowcake after 240 days of submersion in
the ocean. According to the OECD, uranium may be extracted from
seawater using this method for about $300/kg-U. The experiment by
Seko
et al. was repeated by Tamada et al. in 2006.
They found that the cost varied from ¥15,000 to ¥88,000 (Yen)
depending on assumptions and "The lowest cost attainable now is
¥25,000 with 4g-U/kg-adsorbent used in the sea area of Okinawa,
with 18 repetitionuses [sic]." With the May, 2008 exchange
rate, this was about $240/kg-U.
Rise, stagnation, renaissance and opposition to uranium
mining
In the beginning of the
Cold War, to ensure
adequate supplies of uranium for national defense, the United
States Congress passed the
U.S. Atomic Energy Act of 1946,
creating the
Atomic Energy
Commission (AEC) which had the power to withdraw prospective
uranium mining land from public purchase, and also to manipulate
the price of uranium to meet national needs. By setting a high
price for uranium ore, the AEC created a uranium "boom" in the
early 1950s, which attracted many prospectors to the
four corners region of the
country.
Moab,
Utah
became known as the Uranium-capital of the world,
when geologist Charles Steen
discovered such an ore in 1952, even though American ore sources
were considerably less potent than those in the Belgian Congo or
South Africa.
At the height of the
nuclear energy
euphoria in the 1950s methods
for extracting diluted uranium and
thorium,
found in abundance in
granite or
seawater, were pursued. Scientists promised that,
used in a
breeder reactor, these
materials would potentially provide limitless source of
energy.
American military requirements declined in the 1960s, and the
government completed its uranium procurement program by the end of
1970. Simultaneously, a new market emerged: commercial nuclear
power plants.
However, in the U.S. this market virtually
collapsed by the end of the 1970s as a result of industrial strains
caused by the energy crisis, popular
opposition, and finally the Three Mile
Island nuclear accident
in 1979, all of which led to a de facto
moratorium on the development of new nuclear reactor power
stations.
In Europe a mixed situation exists. Considerable nuclear power
capacities have been developed, notably in Belgium, France,
Germany, Spain, Sweden, Switzerland and the UK. In many countries
development of
nuclear power has been
stopped and phased out by legal actions. In Italy the use of
nuclear power was barred by a
referendum
in 1987, however this is now under revision. Ireland also has no
plans to change its non-nuclear stance and pursue nuclear power in
the future.
Opposition to uranium mining has been considerable in Australia,
where notable anti-uranium activists have included
Kevin Buzzacott,
Jacqui Katona,
Yvonne Margarula, and
Jillian Marsh. Other notable anti-uranium
activists include
Manuel Pinto (USA),
JoAnn Tall (USA), and
Sun Xiaodi (China).
Since 1981 uranium prices and quantities in the US are reported by
the
Department of
Energy.The import price dropped from
32.90 US$/lb-U
3O
8 in 1981 down to 12.55
in 1990 and to below 10 US$/lb-U
3O
8 in
the year 2000. Prices paid for uranium during the 1970s were
higher, 43 US$/lb-U
3O
8 is reported as
the selling price for Australian uranium in 1978 by the
Nuclear Information Centre.
Uranium prices reached an all-time low in 2001, costing US$7/lb,
but has since rebounded strongly. In April 2007 the price of
Uranium on the spot market rose to US$113.00/lb, This is very close
to the all time high (adjusted for inflation) in 1977. a high point
of the
uranium bubble of
2007. The higher price has spurred expansion of current mines,
construction of new mines and reopening of old mines as well as new
prospecting.
Health risks of uranium mining
Because uranium ore emits
radon gas, uranium
mining can be more dangerous than other underground mining, unless
adequate ventilation systems are installed. During the 1950s, many
Navajos in the U.S. became uranium
miners, as many uranium deposits were discovered on Navajo
reservations. A statistically significant
subset of these early miners later developed
small cell carcinoma after exposure to
uranium ore.
Radon-222, a natural
decay product of uranium, has been shown to be
the cancer-causing agent. Some American survivors and their
descendants received compensation under the
Radiation Exposure
Compensation Act in 1990.
In January 2008
Areva was nominated for an
Anti Oscar Award. The French state-owned company mines uranium in
northern Niger where mine workers are not informed about health
risks, and analysis shows radioactive contamination of air, water
and soil. The local organization that represents the mine workers,
spoke of "suspicious deaths among the workers, caused by
radioactive dust and contaminated groundwater."
Clean Up Efforts
Despite
efforts made in cleaning up uranium sites, significant problems
stemming from the legacy of uranium development still exist today
on the Navajo Nation and in the states of Utah
, Colorado
, New
Mexico
, and Arizona
. Hundreds of abandoned mines have not been
cleaned up and present environmental and health risks in many
communities.
[281359] At the request of the U.S. House
Committee on Oversight and Government Reform in October 2007, and
in consultation with the Navajo Nation, the Environmental
Protection Agency (EPA), along with the Bureau of Indian Affairs
(BIA), the Nuclear Regulatory Commission (NRC), the Department of
Energy (DOE), and the Indian Health Service (IHS), developed a
coordinated Five-Year Plan to address uranium contamination.
[281360] Similar interagency coordination
efforts are beginning in the State of New Mexico as well.
Further reading
See also
References
- Franz J. Dahlkamp (1993) Uranium ore deposits
Springer-Verlag, Berlin, 460 p. ISBN 3-540-53264-1.
- Australia's anti-nuclear movement: a short history(26
August 1998)By Jim Green, Green Left
- Nuffield, E. W., 1955, Geology of the Montreal River Area;
Ontario Department of Mines, Volume LXIV, Part 3,
Sixty-Fourth Annual Report.
- Carlie F. Banks (1976) Uranium and the Uranium Industry in
Canada, Richardson, Tex.: Suntech Inc., p. 36–37.
- Chisholm, B., and Gutsche, A., Superior, Under the Shadow
of the Gods, Lynx Images, 1998, p. 45.
- J. B. Mawdsley (1958) The radioactive pegmatities of
Saskatchewan, in Proceedings of the Second United Nations
International Conference on the Peaceful Uses of Atomic Energy,
p. 484–490.
- Robert J. Wright and Donald L. Everhart (1960)
Uranium, in Mineral Resources of Colorado First Sequel,
Denver: Colorado Mineral Resources Board, p. 329–365.
- New uranium mining halted at Canyon - Interior
Dept. questions order issued by House committeeGinger D.
Richardson,The Arizona Republic(Jun. 26, 2008)
- See article in Czech:
:cs:Koncentrační tábory při československých uranových
dolech.
- Uranium Mining in Finland: Fighting Prospectors in
the Nuclear Age - URANIUM MINING IN FINLAND By Renate
Nimtz-Köster(05/29/2007)SPIEGEL ONLINE
- About
UsUranium National Company S.A.
- Košice does not want uranium mines(27 Feb 2006) - The
Slovak Spectator
- Cornwall Calling: South Terras Mine,
Cornwall
- George J. Coakley (2004) Namibia, in Minerals
Yearbook, Area Reports: International 2002, Africa and the Middle
East, U.S. Geological Survey, p. 24.2.
- Langer Heinrich mine
- Thomas R. Yager (2004) Burkina Faso, Mauritania, and
Niger, in Minerals Yearbook, Area Reports: International 2002,
Africa and the Middle East, U.S. Geological Survey,
p. 6.2.
- 2007 Annual report of the Euratom Supply Agency
- Google translate: Symposium on nuclear reactors in
the "atomic energy"
- Aborigines count cost of mine(25 May, 2004) By
Phil Mercer, BBC correspondent in Darwin, BBC NEWS /
ASIA-PACIFIC
- Anti-uranium demos in Australia(5 April,
1998)BBC World Service
- Anti-nuke protests(16 July 1997)By Jennifer Thompson,
Green Left Weekly
External links