Recovery of Zinc from Flotation Tailings of Lead–Zinc Ore Through a Hydrometallurgical Route

Abstract

This study focuses on recovering zinc from flotation tailings through a hydrometallurgical route, including sequential H₂SO₄ leaching, iron precipitation, and solvent extraction (SX) processes. The effect of leachate concentration, leaching temperature, and time on the zinc recovery was investigated at constant solid/liquid ratio and stirring rate. In order to remove impurities from the pregnant leach solution (PLS), dissolved iron was first precipitated with NaOH solution, and then the dissolved zinc ions were extracted selectively by D2EHPA. Finally, the zinc in the organic D2EHPA phase was stripped into an aqueous phase by utilizing H₂SO₄ solution to obtain a concentrated and purified zinc solution. It was seen that 93.50% of zinc in the tailings could be leached under optimum leaching conditions. In the SX process, the organic phases, prepared at organic/aqueous ratio (O/A) of 1/1 by volume, could extract 95.3% of the zinc in the pregnant leach solution within 10 min of extraction time. The stripping of 96.83% zinc into the aqueous phase was possible by using a 0.5-M H₂SO₄ solution, prepared at an O/A ratio of 1/1 by volume. Calculations showed that an 82.65% of cumulative zinc recovery could be achieved through the proposed leaching and SX route.