Vacuum distillation: A sustainable separation and purification approach for extracting valuable metals from In-Zn, In-Sn, and In-Sn-Zn waste alloys

The vacuum distillation (VD) method was studied for extraction of valuable metals from In-Zn, In-Sn, and In-Sn-Zn waste alloys. The VD studies were carried out between 773 K and 1073 K, at 5 Pa, and for 60 min for the In-Zn alloys. The In content in the residues was greater than 99.999 wt%, and the Zn content in the volatiles was the highest at 99.8962 wt%. For the In-Sn alloys, the VD experiments were carried out from 1323 K to 1573 K at 5 Pa for 540 min for the In-Sn alloys. The Sn content in the residues exceeded 99.9963 wt%, whereas the In content in the volatiles was 99.86 wt%. Further, the In-Sn-Zn VD was carried out between 773 K and 1073 K at 5 Pa for 90 min. The Zn content of the residues decreased from 6.0 wt% to 0.0009 wt%, while the Zn content of the volatiles was 99.79 wt%. Using the M-MIVM and vapor-liquid equilibrium (VLE) theories, the VLE data was predicted and the related phase diagrams for the binary and ternary alloys were displayed. The remarkable similarity between theoretical and experimental VLE phase diagrams demonstrates the reliability of the M-MIVM for In-based alloys.