Study on iron purification from aluminium melt by Na 2 B 4 O 7 flux

Abstract

A study was carried out to investigate the effect of Na₂B₄O₇ on the reduction of Fe concentration from commercial purity aluminium. Experiments were conducted and the double barrier layers theory was used to study the kinetics of the purification process. Results showed that the iron reduction ratio increased with the addition of Na₂B₄O₇ and the holding time, which follows the first order exponential decay law. The addition of Na₂B₄O₇ containing flux could reduce iron content from 0·14 wt-% to less than 0·1 wt-% and achieve an optimal ratio of 44%. Thermodynamic calculations and the XRD, SEM and EDX analyses of the molten sludge indicated that formation of Fe₂B could occur spontaneously in molten aluminium with the addition of Na₂B₄O₇ containing flux.