Removal of Iron Impurity from Aluminum by Electroslag Refining

Abstract

The effect of electroslag refining on removal of iron from commercial purity aluminum using KCl-NaCl-Na₃AlF₆ slag containing Na₂B₄O₇ was studied. The iron content decreases with the decrement of the remelting speed and the iron content can decrease from 0.42% to 0.20 mass% after electroslag refining. The chemical reaction between melt and slag to form Fe₂B in the electroslag refining process is the main reason for the reduction of iron content. Thermodynamic calculation of the chemical reaction theoretically accounts for the formation of Fe₂B spontaneously in the electroslag refining process. The ultimate strength and elongation of commercial aluminum are improved obviously after electroslag refining.