A novel approach for recovering multiple valuable metals from gallium-rich residues of phosphorus flue dust by two-stage vacuum reduction

In this study, the gallium-rich residue (GRR) obtained from phosphorus flue dust (PFD) after phosphorus removal was taken as the research object, and a novel technology for efficient recovery of valuable metals from GRR was proposed. This technology mainly adopted a two-stage vacuum carbothermal reduction process to selectively recover Zn and Pb and concentrate Ga. The feasibility of separating these three metals from GRR was investigated by thermodynamic analysis, and the effects of temperature, reducing agent dosage and holding time on metals recovery were explored. A promising recovery rate of up to 96.84%, 97.98% and 86.32% was achieved for Zn, Pb and Ga, respectively, under the optimal conditions. The purity of Zn and Pb in the condensate reached 98.57% and 80.56%, respectively, which can be used as raw materials for downstream enterprises and have high economic value. Additionally, the resulting Ga-rich condensate contained 1.49 % Ga, which is much higher than other traditional Ga-containing secondary resources, and can be further purified by hydrometallurgical process or other technologies. The whole process has almost no secondary pollution, with remarkable efficiency, providing a new approach for the comprehensive utilization of PFD.