From Bauxite to recycled metal
There is plenty of raw material for the production of aluminium. In a variety of forms, aluminium compounds make up a full 8% of the Earth’s crust.
Bauxite is the main starting point in the production of aluminium. It has been estimated that, given the present rate of aluminium production, there is enough bauxite to last another 200 to 400 years. This assumes no increase in the use of recycled aluminium and no further discoveries of bauxite.
Bauxite forms when certain aluminium bearing rocks decompose. Its main constituents are aluminium oxides, iron and silicon. The largest and most lucrative bauxite deposits are located around the Equator. Major producers include Australia, Brazil, Jamaica and Surinam.
Normally in close proximity to the mine, bauxite is refined into alumina. The next stage, production of aluminium by molten electrolysis of the alumina, is concentrated in countries with good supplies of electricity. The production of 1Kg of aluminium requires around 2Kg of alumina. The production of 2Kg of alumina requires about 4Kg of bauxite.
Due to aluminium’s chemistry, relatively large amounts of energy (primarily electricity) are required to reduce alumina to aluminium. Around 47 MJ (approx 13kWh) goes into the molten electrolysis of 1Kg of the metal. However, this investment gives excellent dividends.
The energy expended in aluminium production is often recouped several times over. By reducing the weight of vehicles, the use of aluminium reduces fuel consumption. Similarly, energy losses in aluminium power lines are comparatively small.
Scrap aluminium is a valuable resource that is set to become even more important. In principle, all scrapped aluminium can be recycled into a new generation of products.
With appropriate sorting, scrap aluminium can advantageously be recycled to produce the same sorts of products over and over again. Furthermore, recycling requires only 5% of the original energy input.
So easy to recycle: Aluminium is the perfect ‘eco-metal’. Very little aluminium is lost in the remelting process. Increased recovery, dismantling and sorting of spent products has led to even greater recycling of aluminium.