Zinc Removal from Basic Oxygen Steelmaking Filter Cake by Leaching with Organic Acids

The dust generated from the basic oxygen steelmaking (BOS) process is a waste material mainly containing iron that cannot be recycled owing to its high zinc content. In this study, the leaching effects of different organic acids are compared, with the aim of determining an acid that selectively leaches and removes zinc from BOS dust, so that the waste material can be recycled into ironmaking and steelmaking processes in order to substitute part of the raw materials of steelmaking. The dust used in this study was scrubbed and collected in the form of a filter cake. The acids tested were oxalic, citric, acetic, propionic, butyric, and valeric acids. Butyric acid was found to be the most effective, with a high zinc extraction level of 49.7 pct and a low iron level of only 2.5 pct. Oxalic acid was the least effective leaching reagent for both zinc and iron extractions, owing to the formation of zinc and iron oxalate precipitates following metal dissolution. The filter cake and leached residues were characterized by chemical analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy with energy dispersive spectroscpopy.