From leaching data to release estimates: Screening and scenario assessments of electric arc furnace (EAF) slag under unencapsulated use

• Published in: Journal of hazardous materials Vol. 479; p. 135522
• Main Authors: Yu, Siyuan, Garrabrants, Andrew C., DeLapp, Rossane C., Hubner, Tara, Thorneloe, Susan A., Kosson, David S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05-11-2024
• Subjects: Electric arc furnace slag; L/S-dependent data; Leaching assessment; Leaching Environmental Assessment Framework; pH-dependent data; Leaching Environmental Assessment Framework; pH-dependent data; L/S-dependent data; Electric arc furnace slag; Leaching assessment
• DOI: 10.1016/j.jhazmat.2024.135522
• EISSN: 1873-3336
• ISSN: 0304-3894; 1873-3336

Electric arc furnace (EAF) slag is the non-metallic byproduct of the primary U.S. steelmaking process. Much of the slag is marked for secondary uses as aggregates. EAF slags used as construction fill or residential groundcover are directly exposed to the environment, raising concerns of potential leaching impacts. Leaching data of EAF slags as function of eluate pH (Method 1313) and liquid-to-solid ratio (Method 1314) were used to refine an initial list of constituents of potential concern to those with potential to leach at concentrations greater than project thresholds, and to estimate release from EAF slags when used as unencapsulated groundcover. Screening assessment identified 11 of over 20 constituents requiring further assessment. Scenario-based assessments results showed that constituents with high available content and low leaching concentrations (Al, Cr, Co, Mn, Se) are persistent in contacting water over the assessment period while those with limited available content (As, Ba, Mo, V) were depleted. Aging decreased the release of Se while increasing Tl release, likely through a combination of hydration, carbonation, and cracking processes. Increasing fill depth and infiltration rates did not alter leaching concentrations; however, liquid-solid ratio for each assessment interval changed thereby impacting cumulative release.
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•Leaching assessment of EAF slag used as unencapsulated residential groundcover.•Assessment ratios compare eluate data to thresholds for all potential constituents.•Scenario assessment indicated that As, Ba, Mo and V depleted within 30 years.•Field-aged slags showed decreased As, Sr, and Se and increased Tl concentrations.•Fill depth and infiltration rate impact release, but not solubility concentrations.