World Mineral Production - NERC Open Research Archive - Natural ...

BAUXITE – ALUMINA – ALUMINIUM
Characteristics
Bauxite, the most common ore of aluminium, is a hard,
reddish, clay-like material. It was first discovered near the
village of Les Baux in southern France. Bauxite occurs in
three main forms: gibbsite (aluminium hydroxide), böhmite
and diaspore (both aluminium-oxide-hydroxides). Gibbsite is
the dominant form mined. Bauxite is a residual type of ore
deposit that has been left on the land surface following intense
weathering and the removal by leaching of other minerals.
Consequently, it tends to occur mainly in tropical and subtropical
regions such as the Caribbean, parts of Africa, South
America, and Australia. The largest reserves of bauxite are in
Guinea (7400 million tonnes), Australia (5800 million tonnes)
and Jamaica (2000 million tonnes); (Bray, 2008).
Alumina (aluminium oxide) is a white granular material
produced from bauxite by the Bayer refining process, which
involves dissolving the bauxite in caustic soda at high
temperature and pressure. Aluminium hydroxide is then
precipitated from the liquid and this is calcined to form
aluminium oxide powder.
Aluminium metal is produced by the electrolysis of alumina
dissolved in a molten salt in a smelter. This process is a very
large consumer of electrical power and as a consequence the
availability of cheap electricity tends to determine the location
of aluminium smelters.
Pure aluminium is a silver-white metal with many desirable
characteristics. It is light, non-toxic, non-magnetic and nonsparking.
It is easily formed, machined or cast, and forms alloys
with many other metals such as copper, magnesium, and silicon.
Aluminium and most of its alloys are highly resistant to corrosion.
It is also a very good conductor of electricity (IAI, 2007).
Uses
Bauxite is primarily used to produce alumina through the
Bayer process. However, between 5 and 15 per cent of bauxite
is of non-metallurgical grade and most of this is calcined into
‘brown fused alumina’ for use in the abrasive or refractory
markets.
Approximately 90 per cent of alumina produced in the world
is used in the production of aluminium metal through
smelting. Some of the remaining 10 per cent is calcined at
higher temperatures than smelter grade alumina and is used
for a wide range of refractory and ceramic purposes. Fused
alumina is formed in electric arc furnaces at high
temperatures and is used in the manufacture of abrasives and
refractories (Tran, 2007a).
Aluminium is, in terms of tonnage, the most widely used nonferrous
metal. It is used extensively in the transport
manufacturing industry (most importantly in the aerospace
industry but also in road vehicles, trains and ships), packaging
(cans, foil), water treatment, construction (windows, doors,
wire), cooking utensils, electrical transmission lines,
electronics, CDs and transistors. It is also used in paints and
rocket fuel. In most uses it is alloyed with small amounts of
other metals such as magnesium and manganese. Recycling is
an important feature of aluminium use and recycled metal
(including manufacturing scrap) contributes about 39 per cent
of consumption.
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World production in 2006
Australia mined the most bauxite in 2006, extracting 32 per
cent of the world total. Production here has increased by
14 per cent since 2002. The second largest is Brazil, with
12 per cent, closely followed by China, with an estimated
11 per cent. China’s bauxite production has risen by 62 per
cent since 2002 (although it remains heavily dependent on
bauxite imports), whereas Brazil’s production has risen by
74 per cent over the same period.
The fourth largest producer of bauxite in the world is Guinea.
Here production fell in 2006 compared to 2005, and the
increase from 2002 to 2005 was only 10 per cent resulting in
volumes falling below those of Brazil and China. The other
country showing a significant rise is India, where production
has increased by 54 per cent since 2002. In 2006 India’s
output overtook that of Jamaica, which had been a major
producer of bauxite for many years.
Australia is also the world’s largest producer of alumina, with
25 per cent of the world total. China is the second largest
producer, with 19 per cent. Other major producers are Brazil,
with nine per cent of the world’s total; the USA, with seven
per cent; and Jamaica, with six per cent. Production in China
has increased by more than 150 per cent since 2002 and
Brazil’s output has increased by 74 per cent over the same
period. Romania and Azerbaijan have also shown significant
increases since 2002, although each had only one per cent of
the world production total in 2006.
The world’s largest aluminium metal producer is China, with 28
per cent of the world total. The next biggest producers are
Russia, with 11 per cent, and Canada, with nine per cent.
China’s aluminium production has increased by 116 per cent
since 2002. Mozambique also increased output significantly,
rising by 106 per cent since 2002, Bahrain’s grew by 69 per cent
and India by 60 per cent, although these countries each had two
or three per cent of the total world production in 2006. By
contrast, aluminium production in the USA fell by 16 per cent in
the five years since 2002.
Prices
Metallurgical grade bauxite and alumina are mostly traded on
long-term contracts and typical prices are not published.
During 2007, Chinese refractory grade bauxite generally
traded in the range US$130 to US$160 per tonne, depending
on the specification, with Guyanan refractory grade bauxite
ranging from US$165 to US$235 per tonne (Tran, 2007b).
Spot prices for metallurgical grade alumina were relatively
stable throughout 2007, at around US$350 per tonne. This
compares to a dramatic rise and fall that occurred in 2006 with
prices reaching a high of over US$600 per tonne in April 2006
and a low of nearly US$200 per tonne in December 2006
(Metal Bulletin, 2008).
The London Metal Exchange official daily cash price for
aluminium ingot showed a generally increasing trend from
below US$1500 per tonne in 2003 to nearly US$3000 per
tonne by mid-2007, despite a sharp fall in May 2005 and a
spike in May 2006 (Metal Bulletin, 2008). In the latter half of
2007 the price fell to below US$2500 per tonne as a result of
weaker demand.