Title
Selective recovery of Cr from stainless steel slag by alkaline roasting followed by water leachingSelective recovery of Cr from stainless steel slag by alkaline roasting followed by water leaching
Author
Faculty/Department
Faculty of Sciences. Bioscience Engineering
Research group
Sustainable Energy, Air and Water Technology
Publication type
article
Publication
Amsterdam,
Subject
Physics
Engineering sciences. Technology
Source (journal)
Hydrometallurgy. - Amsterdam
Volume/pages
158(2015), p. 139-148
ISSN
0304-386X
ISI
000366768000019
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
Selective chromium (Cr) leaching from stainless steel slag (SS slag) by alkali roasting followed by water leaching was investigated. The efficiency of the alkali roasting process for Cr leaching was increased by optimizing the mass ratio of alkaline agents (NaOH, and NaOH-NaNO3) to the slag, roasting temperature and time. At the optimum condition (0.67 mass ratio of NaOH to SS slag, 400 degrees C, 2 h) of NaOH roasting, chromium leaching was around 83%, while the matrix material was dissolved only to a limited extent (Si 8.0%). Mechanical activation of the SS slag prior to roasting reduced the optimum NaOH to SS slag mass ratio to 0.4. The addition of NaNO3 as an oxidant to the NaOH salt increased Cr leaching to 89% after roasting at 400 degrees C for 2 h. The remaining Cr phases in the residue were almost exclusively FeCr alloys. Further chromium dissolution from these alloys is prevented by a passivation layer of Fe oxides as shown by SEM/EDS images. Based on these results, a SS slag recycling process is suggested in which roasting-water leaching followed by water washing to remove Cr yields a residue which has potential for application as a construction material. (C) 2015 Elsevier B.V. All rights reserved.
E-info
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