Selective leaching of zinc from blast furnace dust with mono-ligand and mixed-ligand complex leaching systems

The nonferrous metals in blast furnace dust, especially zinc, which used to be categorized as hazardous components for blast furnace, are worthy of recovery in this economy. In this paper, a novel processing for extracting zinc from blast furnace dust by using a coordination reaction between the organic ligand and zinc ions was proposed. When blast furnace dust was leached in a 0.2 M iminodiacetic acid (Ida) solution at 20 °C for 2 h with a liquid-to-solid ratio of 10 mL/g, the leaching rates of zinc and iron were 62.78% and 6.07%, respectively. To accomplish the maximum separation of zinc from iron during the leaching process, a mixed-ligand complex leaching system consisting of Ida as the primary ligand and ammonium as the secondary ligand was developed. The optimal conditions for the leaching process with a mixed-ligand complex leaching system were investigated. We found that 65.58% of zinc was extracted by the solution with Ida:NH4Cl:NH3·H2O at 0.2:2:2 M and a 20:1 liquid-to-solid ratio at 40 °C for 2 h.