Study on iron purification from aluminium melt by Na_2B_4O_7 flux

摘要

A study was carried out to investigate the effect of Na_2B_4O_7 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 Na_2B_4O_7 and the holding time, which follows the first order exponential decay law. The addition of Na_2B_4O_7 containing flux could reduce iron content from 0.4 wt- percent to less than 0.1 wt- percent and achieve an optimal ratio of 44 percent. Thermodynamic calculations and the XRD, SEM and EDX analyses of the molten sludge indicated that formation of Fe_2B could occur spontaneously in molten aluminium with the addition of Na_2B_4O_7 containing flux.