Recovery of zinc and manganese from pyrometallurgy sludge by hydrometallurgical processing

In this contribution, a hydrometallurgical process is specifically developed to recover zinc (Zn), manganese (Mn) and lead (Pb) from the pyrometallurgical sludge produced in the steel manufacturing industries. The optimum conditions for Zn and Mn selective leaching from the pyrometallurgical sludge of Pompey have been already found. This process consists of six unit operations:& para;& para;1) Selective Zn leaching. At this stage, 80.8-100% of Zn is extracted.& para;& para;2) Selective Mn leaching, with two reductive leaching steps: fixed pH range from 3.5 to 4.2 and redox potential lower than 400 mV, using H2SO4 and Na2S2O5 as the reducing agent. In this step, 77.6-95.9% of Mn is recovered.& para;& para;3) Removal of aluminum (Al) and iron (Fe) from Zn leach liquor by chemical precipitation at pH 4.8 with NaOH.& para;& para;4) Removal of Al, Zn and Pb by sulfide precipitation (Na2S) from Mn leach liquor (2) at pH 5.6.& para;& para;5) Zn precipitation (as sphalerite) using twice the stoichiometry value of Na2S (considering the concentration of Zn).& para;& para;6) Mn precipitation (as rhodochrosite) at pH 8.5 using Na2CO3 as the precipitation agent. This process is tested with four different raw materials, which demonstrates its reliability. (C) 2017 Elsevier Ltd. All rights reserved.