The challenge of sustainable aluminium

Aluminium is the second most produced metal in the world after steel. Its lightweight and corrosive resistant properties make it an attractive material for transport, structures and packaging. In your home, you are likely to find that your door, window frames and a lot of your kitchen equipment are made from aluminium. Your car will certainly have some aluminium, and ‘mag’ wheels are actually made from an alloy of aluminium and magnesium. I am always grateful that aluminium is one third the density of steel when I drag my step ladder out of the garage!

These excellent properties have seen aluminium demand grow around the world since it was first commercially produced over a hundred years ago in North America and Europe. Currently, over 30 million tonnes a year is made around the world, much of it in China, North America and Europe, with substantial production in the Middle East and Australia.
In Malaysia, a new aluminium smelter is now operating based around the hydroelectricity generated from the Bakun Dam. This project will see Malaysia become a major player in this important industry, as there are plans to build more smelters in the region.

Expansion of Malaysian production is also likely to benefit Australia because it is the world’s leading producer of alumina (essentially aluminium and oxygen combined) – the major raw material for aluminium production.
The process for producing aluminium from alumina is called the Hall-Heroult process and is named after a French man (Heroult) and an American (Hall) who simultaneously invented the process in the 19th century. Because the bond between aluminium and oxygen is so strong, extreme conditions are required to free the metal from the oxide. The Hall-Heroult ‘cells’ operate at around 1000 degrees celsius and use an electrochemical reaction (the reverse process of what is going on in a battery) to produce molten metal. Unfortunately, nearly half of the electrical energy coming into the cell is lost as low-grade heat from the system because of problems associated with the extreme conditions within the system.

The aluminium industry is also a major source of export income for Australia. However, the primary production of aluminium is highly energy-intensive and a generator of significant greenhouse gases.
This problem is particularly acute in Australia where most of the energy used for aluminium production is from coal fired power stations. Approximately 13 per cent of Australia’s electricity supply is used to produce aluminium. Lowering the energy consumption associated with this valued metal is vital to Australia’s interest.

Significant reductions in energy consumption for aluminium production would also be highly beneficial to Australia and Malaysia in terms of economic development and in meeting the goals of the Kyoto protocol. The long term future of the whole metals industry is tied to the need to develop sustainable means of production.

To address these issues, a cluster of five Australasian universities led by myself with Swinburne University of Technology as the lead party, has been formed to address these significant challenges. The emphasis is on innovation in materials (to limit heat loss), overall energy reduction and development of new ways of making aluminium with a lower environmental footprint. The cluster, formally the ‘Breakthrough Technology for Primary Aluminium Cluster’, commenced operation in June 2009 with an initial operating budget of A$8 million over three years.

The cluster’s research program combines a unique array of world-class research expertise in chemical thermodynamics, chemical kinetics, process kinetics, materials science, electrochemistry and fluid dynamics. The expertise of the High Temperature Processing Group at Swinburne (see http://www.swinburne.edu.au/feis/htp//) feeds directly into these topics, especially through the expertise of Professor Yos Morsi, Dr Akbar Rhamdhani and myself.

For example, Dr Rhamdhani is using his expertise in predicting the outcome of chemical reactions and modern computer modelling techniques to examine new ways to produce aluminium. The computer programs allow various reactions to be evaluated without doing the actual experiments. Already, an exciting new approach has emerged and researchers at Swinburne are exploring the potential of this new route.

It appears that Malaysia and Australia will share a common challenge into the future. That is, how do we lower the environmental footprint of aluminium and provide a sustainable future for this valuable metal?

Geoffrey Brooks is professor within the Faculty of Engineering and Industrial Sciences at Swinburne University of Technology, Australia.