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Title: Aqueous solubility of Cr(VI) compounds in ferrochrome bag filter dust and the implications thereof

The production of ferrochrome (FeCr) is a reducing process. However, it is impossible to completely exclude oxygen from all of the high-temperature production process steps, which may lead to unintentional formation of small amounts of Cr(VI). The majority of Cr(VI) is associated with particles found in the off-gas of the high-temperature processes, which are cleaned by means of venturi scrubbers or bag filter dust (BFD) systems. BFD contains the highest concentration of Cr(VI) of all FeCr wastes. In this study, the solubility of Cr(VI) present in BFD was determined by evaluating four different BFD samples. The results indicate that the currently applied Cr(VI) treatment strategies of the FeCr producer (with process water pH ≤ 9) only effectively extract and treat the water-soluble Cr(VI) compounds, which merely represented approximately 31% of the total Cr(VI) present in the BFD samples evaluated. Extended extraction time, within the afore-mentioned pH range, proved futile in extracting sparingly-soluble and water-insoluble Cr(VI) species, which represented approximately 34% and 35% of the total Cr(VI), respectively. Due to the deficiencies of the current treatment strategies, it is highly likely that sparingly water-soluble Cr(VI) compounds will leach from waste storage facilities (e.g. slimes dams) over time. Therefore, it is criticalmore » that improved Cr(VI) treatment strategies be formulated, which should be an important future perspective for FeCr producers and researchers alike.« less
Authors:
; ; ; ; ;
Publication Date:
Grant/Contract Number:
FG03-97ER45628; W-31-109-Eng-38; 101345
Type:
Accepted Manuscript
Journal Name:
Water SA
Additional Journal Information:
Journal Volume: 43; Journal Issue: 2; Journal ID: ISSN 0378-4738
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); North-West Univ., Potchefstroom (South Africa); Natural Resources Canada, Ottawa, ON (Canada)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Research Foundation (NRF) (South Africa); Natural Sciences and Engineering Research Council of Canada (NSERC)
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; hexavalent chromium; Cr(VI); ferrochromium; ferrochrome; bag filter dust; smelter waste
OSTI Identifier:
1425801
Alternate Identifier(s):
OSTI ID: 1417378