The Effectiveness of Zn Leaching from EAFD Using Caustic Soda

• Published in: Water, air, and soil pollution air, and soil pollution, 2018-02, Vol.229 (2), p.1-10, Article 33
• Main Authors: Al-Makhadmeh, Leema A., Batiha, Mohammad A., Al-Harahsheh, Mohammad S., Altarawneh, Ibrahem S., Rawadieh, Saleh E.
• Format: Article
• Language: English
• Subjects: Atmospheric particulates; Atmospheric Protection/Air Quality Control/Air Pollution; Caustic leaching; Caustic soda; Chemical engineering; Climate Change/Climate Change Impacts; Dust; Dust storms; Earth and Environmental Science; Electric contacts; Environment; Environmental monitoring; Ferric oxide; Fluorescence; Furnaces; Halite; Halites; Hazardous wastes; Hydrogeology; Hydrometallurgy; Iron; Iron compounds; Iron oxides; Leaching; Lead; Magnetite; Metals; pH effects; Recycling; Residues; Sodium hydroxide; Soil Science & Conservation; Solutions; Sylvite; Toxic wastes; Water Quality/Water Pollution; X-ray diffraction; X-ray fluorescence; X-ray spectroscopy; X-rays; Zinc; Zinc oxide; Zinc oxides
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-018-3694-4

Electric arc furnace dust (EAFD) is a toxic waste which is mainly rich in iron oxide, zinc, and lead. Hydrometallurgical extraction of zinc from Jordanian EAFD in alkaline medium was investigated; NaOH, NaHCO 3 , and Na 2 CO 3 were used as leaching agents. The pH values for the prepared solutions were 8.3, 8.2, and 12.55 for NaHCO 3 , Na 2 CO 3 , and NaOH, respectively. The effect of NaOH concentration (1, 3, 5, 7, and 9 M), contact time (5 min to 3 h), temperature (20, 40, and 60), and solid-to-liquid ratio (SLR; 20, 40, 80, and 120 mg/ml) on the leachability of zinc from EAFD were tested. The initial EAFD and the resulting leach residues were characterized using X-ray diffraction (XRD) and X-ray fluorescence (XRF). EAFD contained 25.9% Zn, 18.0% Fe, and 3.2% Pb. A maximum zinc recovery of 92.9% was achieved using 6 M NaOH at 60 °C with solid loading of 20 g/L and 3 h leaching time. NaHCO 3 and Na 2 CO 3 were not efficient leaching agents for Zn extraction since the recoveries were only 2.6 and 4.5%, respectively. Zn and Pb were depleted in the residues with an E -factor of 0.5–0.6 and 0.1–0.25, respectively. Iron was enriched in the residues; the E -factor was around 2. The EAFD contained mainly zincite, franklinite, and magnetite. After 3 h leaching, only traces of zincite exist in the residues, while sylvite and halite were completely dissolved.