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The drive to cut energy costs in production of aluminum

With investment in aluminum in the Arabian Gulf expected to reach US$55 billion (Dh202bn) in 2020, competition between aluminum smelters is set to become fierce.

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 Aluminum Company (EMAL), the UAE’s state-owned aluminum 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 aluminum plant comprises three areas: the aluminum smelter, the carbon anode, and the cast house.

In very simple terms, aluminum production involves dissolving naturally occurring alumina – aluminum oxide – at very high temperature, placing it in a 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 aluminum 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 per cent savings in gas consumption, depending on furnace design and operation.

The second area is related to the voltage drop in the aluminum 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 aluminum 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 aluminum out – and rebuilt.

The quicker this can be done, the better. We proposed an efficient cooling technique to save about 36 percent 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 aluminum-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 aluminum 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 aluminum market.

And as aluminum smelting accounts for about 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

 

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