Possibilities of Recovering AZ91 Magnesium Alloy from Machining Shavings Contaminated with Oil, through their Fusion with Argon Gas Protection

The automotive industry has increased significantly in the later years the consumption of magnesium based alloys for the manufacture of automotive parts. This metal is mainly applied in carcasses, panels, rims and wheels. Most of the parts are castings that must be machined in certain areas to achieve the required dimensional tolerances. As a result, machining shavings contaminated with mineral oil are originated, and must be recycled to recover the metal. In this process, certain precautions should be taken because of the oil contamination of the chips and the great reactivity of magnesium.This study investigates the recycling of magnesium shavings of the alloy AZ91 (MgAl9Zn1) by using a fusion procedure that is carried out under an inert gas atmosphere of argon, and using small amounts of salt fluxes.The results show significant percentages of metal recovery. However, the metallographic structure of the recycled alloys reveals the presence of pores and non-metallic inclusions and the chemical compositions fall outside the ranges specified by the standard.