x Abu Dhabi, UAETuesday 25 July 2017

The drive to cut energy costs in production of aluminium

To help ensure it ends up in the former category, Emirates Aluminium Company, the UAE’s state-owned aluminium smelter, has turned to the Masdar Institute’s researchers to help improve the efficiency and speed of aspects of the plant’s operation

With investment in aluminium in the Gulf expected to reach US$55 billion in 2020, competition between aluminium smelters is set to become fierce.

And the difference between industry leader and industry laggard may be down to who can run the most efficient plant.

To help ensure it ends up in the former category, Emirates Aluminium Company (Emal), the UAE’s state-owned aluminium smelter, has turned to the Masdar Institute’s researchers to help improve the efficiency and speed of aspects of the plant’s operation.

A typical aluminium plant comprises three areas: the aluminium smelter, the carbon anode, and the cast hour.

In very simple terms, aluminium production involves dissolving naturally occurring alumina – aluminium oxide – at very high temperature, placing it in an steel shelled vat lined with graphite, known as a reduction pot, that serves as a cathode and adding a carbon anode. An electrical current is then passed through the molten metal, causing aluminium metal to be deposited on the lining of the vat.

Three areas of this process are ripe for improvement.

The first is related to the energy efficiency and environmental impact of the gas-fired furnaces within the cast house.

Our research has found room for improvement, resulting in 22% savings in gas consumption, depending on furnace design and operation.

The second area is related to the voltage drop in the aluminium smelter from contact resistance in the anode’s assembly parts – essentially, making sure that as much of the electricity generated is used for the separation process itself as possible, rather than being wasted in other parts of the system.

By saving a few millivolts in the cell voltage drop, a significant amount of power can be saved.

The third area is in the reduction pot rebuild area. Because the process requires aluminium to be deposited on the lining of the vat, every so often it needs to be stopped so the metal can be removed. This requires the pot to be cooled, and then taken apart – to get the aluminium out – and rebuilt. The quicker this can be done, the better. We proposed an efficient cooling technique to save about 36% of cooling time – which means we need about half the space for storing pots that are being cooled or rebuilt.

Collaborations like these are beneficial to both industry and academia. For those of us in academia, working with industry leaders like Emal can provide the opportunity for our students to become familiar with the aluminium smelting process in practice and apply thermal science to relevant industrial applications.

By working together to solve industry problems, we are helping to put both EMAL and the Masdar Institute on the sector map, adding to the body of knowledge about aluminium manufacturing through conference presentations and journal publications, and helping to train skilled and innovative engineers who can eventually play a key role in contributing to the economic growth of the UAE and the region.

For industry, this kind of collaboration and others like it can be seen as a long-term investment that increases the process efficiency, improves environment control and adds value to a business.

With this project, we hope to contribute to the ongoing development and advancement of the UAE’s ambitious and high-potential aluminium market. And as aluminium smelting accounts for around a quarter of the power consumed in the UAE, research aimed at making it more efficient is essential for the UAE’s sustainable economic growth. .

Dr Mohammed Ibrahim Ali is assistant professor of mechanical and materials engineering at the Masdar Institute of Science and Technology.