Recycling of Magnesium Alloy Scrap by Remelting and Chemical De-coating Process

The growing demands of magnesium (Mg) based materials had risen new challenges related to disposal of unused parts and a huge amount of waste made by such metals. Attempts to recycle the scrap of these materials through remelting had become one of the preferred choices. However, a series of preliminary steps should be carried out to reduce the impurities as well as to maintain the quality of the casted ingot, for instance, by applying de-coating for removing paints or coating substrates at the scrap surface prior to remelting. In this research, the effects of chemical reagent decoating on the properties of ingot obtained from recycling Mg scrap were studied. A commercial paint removal liquid was preferred as the reagent for removing paint layers over the Mg scrap surface. The de-coated scrap was then remelted in a conventional furnace with NaCl powder as the fluxing layer. The results of this study noticed the importance of chemical de-coating process to reduce the impurity contents in the ingot which might be originated from the coating or paint substrates covering the Mg scrap. Meanwhile, the density and hardness of the Mg ingot processed without de-coating were obviously higher than that had been cleaned previously with paint removing agent.