Recovery of Zinc from EAF Dust by Alkaline Extraction

Abstract

In this paper, a series of lab-scale experiments have been focused on the zinc recovery from electric arc furnace (EAF) dust by alkaline extraction, combining with the novel alkaline zinc electrowinning technology. Effects of several leaching variables, i.e. leaching time (1-3 h), NaOH concentration (150-400 g/L), solid/liquid ratio (S/L, 1/5-1/12), temperature (30-90 °C) and stirring speed (300-500 rpm) on zinc recovery (%) were investigated. Around 84 %Zn and 92 % Pb were respectively recovered when the leaching process was operated with 250 g/L NaOH and S/L 1/10 at 90 °C for 2 h. After Pb was selectively removed by sodium sulfide precipitation, the alkaline zinc solution was subjected to electrolysis and zinc powder with a purity of 98.5 % was then obtained. The leaching residue is suitable for safe disposal, while the purifying residue can be marketed for lead recovering.