Norway – Following a decade of study and the invention of a specialised piece of equipment, the Norwegian Foundation for Scientific and Industrial Research (SINTEF) is close to the moment of truth for a recycling method for impure aluminium.
At the centre of its work is a four-metre-long piece of equipment containing 40 heating elements which offers a new type of refining procedure. Molten contaminated aluminium is poured into the top of this custom-built apparatus and then passes through a horizontal channel. Meanwhile, a graphite-based rotating screw balances the solidified crystals, thus forcing the pure aluminium upwards to the hottest point, whereas the impurities remain in the cooler portion. As a result, pure aluminium is allowed to exit the machine’s two outlets.
One of the SINTEF experts working on the project is Anne Kvithyld, who won the 2011 Vittorio de Nora Award for her work in aluminium recycling. She states that it is not impossible to strip metals of their impurities; however, they must be separated out properly.
She explains: ‘If we put in aluminium that contains 2% iron, there will still be 2% in the smelt when it emerges, but we can choose for equal amounts to take out 3.9% iron on the dirty side and 0.1% on the clean side.’ According to her, the purity level of the end result depends solely on how long they run the process. Dr Kvithyld adds: ‘We can even set it to produce completely pure recycled aluminium. But for the time being, the most important thing is to upgrade the aluminium to a quality that can be reused.’
The project is currently in its last year of self-financed research, aided by the Research Council of Norway and Hydro. In an upcoming test run in May, a total of 50 kg of contaminated aluminium will be poured into the machine and the resultant streams subjected to a final and official analysis. What happens next depends on those findings.
For more information, visit: www.sintef.no
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