The general approach for RecycAl will be:
- Intensive melt shearing disperses oxide particles in the melt, and they then enhanceheterogeneous nucleation of Fe-containing intermetallics to generate fine and uniformly distributed solid impurity particles in the alloy melt (these are intermetallics formed when Fe combines with the other impurity metals listed above). The intermetallics must then be removed from the melt to provide a refined composition for subsequent casting;
- Conventionally intermetallics are removed from light metals like aluminium and magnesium alloys by settling under gravity. An alternative is to use fine and uniformly distributed inert gas bubbles that are injected into the melt and carry the intermetallic particles to the top surface of the melt to form a dross layer. The use of inert gas injection into an aluminium melt is a standard technique for removing hydrogen and impurities like sodium, lithium and calcium from aluminium melts. It has not been used to date in combination with melt conditioning for the removal of intermetallic particles. The use of inert gas and the settling technique for the removal of the intermetallic particles will be evaluated in the project;
- intermetallic removal from the melt before casting. The de-drossing technique will be developed in the project as will the optimised method of removal of settled intermetallics. The refined liquid can then be used in all casting processes, including shape casting and the casting of rolling blocks or extrusion billets.
TWI Ltd, Brunel University and University College Dublin will work with a consortium of SMEs under the guidance of a large automotive end user (FIAT) to conduct applications-oriented research to demonstrate the capability of the HSP technology for removing Fe-based impurities as described above. The project will also assess the technical and economic feasibility of industrialisation and incorporation into aluminium recycling plants, through the involvement of an industrial enterprisewho is active in municipal solid waste processing (Suldouro), an Al recycling (Idalsa) and Al alloy and component manufacturers (Quantal, GIF, FOMT). Other SME partners (Enginsoft and Azcatec) will assist with economic modelling and life cycle analysis, which will demonstrate the cost and energy savings of the process and the impact on the carbon footprint.