STTR Phase I: Rayleigh Relaxation Centrifuge for Aluminum Purification

This Small Business Technology Transfer (STTR) Phase I project aims to apply knowledge developed from a laboratory astrophysics experiment to the challenge of purification of aluminum. Aluminum more readily oxidizes than any metallic impurities such as iron, which makes purifying aluminum cost prohibitive. This project began as an investigation in liquid metal of angular momentum transport mechanisms responsible for evolution of astrophysical accretion disks. By tailoring the flow properties of the liquid metal, separation of solid impurities entrained in the metal was observed. This project will extend those initial observations to determine the efficiency of impurity separation over a variety of flow parameters. These observations will be used to design an apparatus to demonstrate impurity separation with molten aluminum. The broader impact/commercial potential of this project is to improve the efficiency of aluminum recycling and reduce the energy intensity of aluminum refining. Recycling aluminum requires only 5-8% of the energy required to refine, but accumulates tramp elements which cannot cost effectively be removed. Currently, recycled aluminum is "down cycled" into lower valued products, or diluted with primary aluminum. By developing a cost-effective means of removing impurities, the present project will enable recyclers to produce higher value aluminum alloys with less use of primary aluminum. Primary production of aluminum from alumina uses roughly 1% of global electrical energy, and produces 2.5% of anthropogenic greenhouse gas emissions. Alternative refining processes which would dramatically reduce both electricity needs and emissions are not yet commercially viable, in part due to a need for cost effectively purifying the finished aluminum. As an enabling technology, this project may contribute to the commercialization of alternative refining processes leading to billions of dollars in savings over present production means.