Gallium and other valuable components recovery from phosphorus flue dust by a novel process combining vacuum chlorination and water leaching

Gallium (Ga) is an important strategic metal widely used in the semiconductor manufacturing industry. In this paper, a new vacuum chlorination and water leaching process for simultaneous P fixation and Ga, Pb, and Zn separation from phosphorus flue dust (PFD) using CaCl2 as reagent was proposed. The principle of metal volatilization in vacuum was clarified and the reaction mechanism of chlorination was studied. The impacts of the experimental parameters on the metals volatilization rate were assessed. Under the optimal conditions, Ga volatilization rate reached 97.44 %, the volatilization rates of Pb and Zn respectively reached 98.11 %, and 98.56 % and were highly enriched in the condensation zone, while most of P was converted into water-insoluble Ca2P2O7 and remained in the residue. In addition, the impacts of several factors in the water leaching process on the removal of Cl from the residue were studied. Finally, the leaching solution mainly containing Cl-, K+, and Ca2+ and the water leaching residue with P content of 19.21 % were obtained. This process provides a new clean and sustainable method for the recovery of valuable components in PFD, without the generation of hazardous substances, and therefore it has potential application value.

Automated summary

A new vacuum chlorination and water leaching process for simultaneous P fixation and Ga, Pb, and Zn separation from phosphorus flue dust (PFD) was proposed. The impacts of experimental parameters on the metals volatilization rate were assessed, and under optimal conditions, high volatilization rates were achieved for Ga, Pb, and Zn. Additionally, the impacts of several factors in the water leaching process on the removal of Cl from the residue were studied, resulting in the obtainment of a leaching solution mainly containing Cl-, K+, and Ca2+ and a water leaching residue with high P content.