Removal of iron from molten recycled aluminum through intermediate phase filtration

Aluminum is one of the most versatile materials used in foundry practice; however, iron is one of the most troublesome impurities in aluminum cast materials. During the solidification of aluminum alloys, iron promotes the formation of intermediate phases, which may damage the properties of the final product. In secondary aluminum industries, iron contamination caused by high amounts of iron scrap is always possible. Consequently, the aim of this work was to study the most efficacious method and conditions for the removal of iron from molten aluminum through ceramic filters. The materials studied were based on the AA308 and AA356 aluminum alloys with iron additions. The variables of this work were chemical composition, temperature and the type of filter. The results showed that iron Could be efficiently removed through the use of manganese and silicon followed by the decrease of the temperature at which the intermediate phases crystallize.