|
Bauxite
Bauxite is a heterogeneous material composed primarily of
one or more aluminium hydroxide minerals, plus various mixtures
of silica, iron oxide, clay, titania, aluminosilicate, and
other impurities in minor or trace amounts. Because it is
a mixture of minerals, bauxite itself is not a mineral but
a rock.
Bauxite is reddish-brown, white, tan and tan-yellow.
85% of all the bauxite mined in the world is converted to
aluminium metal, the remaining 15% is consumed in the non-metallurgical
sector. Around two thirds of this is refined via the Bayer
process*, a wet chemical caustic leach method, to make speciality
aluminas such as aluminium hydroxide, calcined aluminas, activated
aluminas, etc. That leaves some 5% of total production which
is used directly in industries such as refractories, abrasives,
cement and steel industries.
The aluminium metal is produced from alumina by passing an
electric current through it in a process called "electrolytic
reduction”.
*In the Bayer process, found in 1888 by the German chemist
Karl Bayer, the bauxite is washed with a hot solution of sodium
hydroxide at 250°C. This converts the alumina, a pure
aluminium oxide, to aluminum hydroxide, which dissolves in
the hydroxide solution. The other components of bauxite do
not dissolve and can be filtered out as solid impurities.
After this first step, the hydroxide solution is cooled, and
the aluminum hydroxide dissolved in it precipitates out as
a white, fluffy solid. When then heated to 1050°C, the
aluminum hydroxide decomposes to alumina, giving off water
vapor in the process.
Links: EAA-The
European Aluminium Association,
The
International Aluminium Institute
World Bauxite Production
Thousand tonnes
| |
2000 |
2001 |
2002 |
2003 |
| Europe |
|
|
|
|
| Bosnia & Herzegovina |
20,7 |
77,0 |
113,0 |
582,9 |
| France |
185,0 |
185,0 |
174,0 |
174,0 |
| Greece |
1.990,5 |
2.052,0 |
2.491,9 |
2.492,4 |
| Hungary |
1.046,5 |
1.000,0 |
720,0 |
665,9 |
| Russia |
5.000,0 |
4.805,0 |
4.585,7 |
5.441,8 |
| Yugoslavia |
630,0 |
610,0 |
611,5 |
540,1 |
| total |
8.872,7 |
8.729,0 |
8.696,1 |
9.897,1 |
| |
|
|
|
|
| Africa |
|
|
|
|
| Ghana |
424,6 |
714,5 |
795,8 |
646,6 |
| Guinea |
17.991,9 |
17.312,1 |
17.480,5 |
16.813,8 |
| Mozambique |
8,1 |
8,6 |
9,1 |
9,1 |
| total |
18.424,6 |
18.036,2 |
18.285,4 |
17.469,4 |
| |
|
|
|
|
| Asia |
|
|
|
|
| China |
7.900,0 |
8.650,0 |
9.999,0 |
9.999,0 |
| India |
7.562,1 |
7.863,9 |
9.947,3 |
9.812,4 |
| Indonesia |
1.175,1 |
1.275,6 |
1.283,5 |
1.262,7 |
| Iran |
485,1 |
273,7 |
323,6 |
323,6 |
| Kazakhstan |
3.729,0 |
3.667,7 |
4.361,1 |
4.737,1 |
| Malaysia |
123,3 |
64,2 |
40,0 |
2,5 |
| Turkey |
458,5 |
242,0 |
287,4 |
287,4 |
| Vietnam |
16,0 |
20,0 |
20,0 |
20, |
| total |
21.449,4 |
22.057,1 |
25.961,9 |
26.444,8 |
| |
|
|
|
|
| America |
|
|
|
|
| Brazil |
14.379,2 |
13.338,1 |
13.147,9 |
13.147,9 |
| Guyana |
2.689,5 |
2.011,3 |
1.639,3 |
1.823,9 |
| Jamaica |
11.126,5 |
12.169,6 |
13.119,4 |
13.444,5 |
| Surinam |
3.610,3 |
4.393,7 |
4.001,6 |
3.500,8 |
| USA |
200,0 |
200,0 |
200,0 |
200,0 |
| Venezuela |
4.360,7 |
4.584,9 |
5.190,8 |
5.190,8 |
| total |
36.366,2 |
36.947,6 |
37.299,0 |
37.307,9 |
| |
|
|
|
|
| Oceania |
|
|
|
|
| Australia/total |
53.802,3 |
53.285,0 |
54.134,0 |
55.626,0 |
| |
|
|
|
|
| World
total |
138.915,2 |
139.054,9 |
144.376,4 |
146.745,3 |
Source: World Bureau of Metal Statistics - World Metal Statistics,
February 2004, p. 6
|
|
