Removal of Iron From Aluminum: A Review

Abstract

In this paper, the Fe-rich phases in and their detrimental effect on aluminum alloys are summarized. The existence of brittle platelet β-Fe-rich phases lowers the mechanical properties of aluminum alloys. The methods to neutralize the detrimental effect of iron are discussed. The use of high cooling rate, solution heat treatment, and addition of elements such as Mn, Cr, Be, Co, Mo, Ni, V, W, Cu, Sr, or the rare earth elements Y, Nd, La, and Ce are reported to modify the platelet Fe-rich phases in aluminum alloys. The mechanism of the modification is briefly described. Technologies to remove iron from aluminum are reviewed extensively. The precipitation and removal of Fe-rich phases (sludge) are discussed. The dense phases can be removed by methods such as gravitational separation, electromagnetic (EM) separation, and centrifuge. Other methods include electrolysis, electro-slag refining, fractional solidification, and fluxing refining. The expensive three-layer cell electrolysis process is the most successful technique to remove iron from aluminum so far.

Keywords:

• alloys
• aluminum
• iron removal
• modification

ACKNOWLEDGMENTS

This research is supported by the Research Board Grant, Laboratory of Green Process Metallurgy and Modeling (GPMM), Material Research Center (MRC), Intelligent Systems Center (ISC) at Missouri University of Science and Technology (Missouri S&T).

Notes

*Data from Couture (Couture 1981). +: increase with increasing Fe content; –: decrease with increasing Fe content; NA: unavailable data.

*Data from Couture (Couture 1981). +: increase with increasing Fe content; –: decrease with increasing Fe content; No: No influence; NA: unavailable data.

*Data from Couture (Couture 1981). +: increase with increasing Fe content; –: decrease with increasing Fe content; No: No influence; NA: unavailable data.