Efficient and selective hydrothermal extraction of zinc from zinc-containing electric arc furnace dust using a novel bifunctional agent

A novel bifunctional reagent of solid ammonium ferric sulfate dodecahydrate (NH4Fe(SO4)2·12H2O) was introduced in this paper to realize the efficient and selective extraction of zinc (Zn) from Zn-containing electric arc furnace (ZEAFD) by using a hydrothermal process. The bifunctional mechanism (extraction of Zn and removal of iron (Fe) in one step during hydrothermal leaching process) was elucidated in detail. The effects of solid NH4Fe(SO4)2·12H2O to ZEAFD after water washing (ZEAFD-w) mass ratio (RN/Z, g/g), hydrothermal temperature and time on Zn and Fe extraction were systematically investigated. It is shown that 93.2% Zn entered into the solution, while 98.4% Fe in the forms of NH4Fe3(SO4)2(OH)6 and Fe2O3 existed in the residue, suggesting that efficient and selective extraction of Zn from the ZEAFD can be realized when hydrothermal process was controlled at 220 °C for 10 h with RN/Z of 7:3.