Leaching characteristics of EAF and AOD stainless steel production dusts
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Aalto University
Antti Kekki   

Aalto University, Department of Materials Science and Engineering, PO Box 16200, FI-0076, Aalto, Finland
Publication date: 2012-06-01
Physicochem. Probl. Miner. Process. 2012;48(2):599–606
In this paper sulfuric acid leaching of four different stainless steel production flue dusts is studied. The main objective is to study and compare the valuable metal Zn, Cr, Ni, Fe, Mo dissolution present in the EAF 1&2 (electric arc furnace) and AOD 1&2 (argon oxygen decarburization converter) dusts. The effect of sulfuric acid concentration, temperature and liquid-to-solid ratio are tested for maximum and selective Zn leaching into solution for recycling purposes. Leaching tests were done in 0.1 M, 0.5 M and 1.5 M sulfuric acid, at temperatures of 30oC, 60oC and 90oC with liquid-to-solid ratios L:S = 10 and 20 under 1 bar pressure for 120 minutes. Maximum Zn dissolution yield was achieved with 1.5M, 90oC, L:S = 10 where the Zn dissolution yield varied from 65% to almost 100%, depending on the dust type (AOD, EAF) and production line (1 or 2). At the same time Cr was leached 7 – 17%, Ni 37 – 48%, Fe 48 – 89% and Mo 82 – 100%. The best zinc selectivity vs. Cr, Ni, Fe, Mo was achieved with 0.5 M, 30oC and L:S 10. The Zn dissolution varied between 33 – 72%, Cr 2 – 4%, Ni 6 – 9%, Fe 2 – 9% and Mo 1 – 55%. Higher temperature and acid concentration resulted in faster dissolution of metals. AOD dust in both lines 1 and 2 has better valuable metal recycling possibilities than EAF dust due to better maximum Zn dissolution and better selective dissolution of Zn vs. Cr, Ni, Fe, Mo.