Process promises cheaper and greener method of de-gassing aluminium

Now researchers at Brunel University London have demonstrated a cheaper and greener method of de-gassing aluminium melt, using ultrasound.

Unless hydrogen gas is removed from aluminium alloys before casting, the resulting solid metals can end up being too porous, and therefore cannot be used.

The existing method, known as argon rotary degassing, involves submerging a graphite rotor into the melt from above. This releases a jet of argon gas which is forced through the melt by the rotating shaft, creating bubbles that float to the surface, collecting any dissolved hydrogen.

However, the process is energy intensive and expensive, as it consumes a lot of argon gas, which is simply released into the atmosphere. The technique also produces turbulence in the melt, leading to the creation of “dross” on the surface, or a mixture of metal and oxide, and thereby wasting some of the valuable material, according to Prof Dmitry Eskin, of the Brunel Centre for Advanced Solidification Technology, who led the research.