Large amounts of electric arc furnace (EAF) slags are generated in the United States as a byproduct of steel production. Multiple utilization scenarios have been considered for EAF slags, including extraction of high-value elements, concrete and cement production, road construction, backfill and residential landscaping. However, EAF slag utilization also needs to consider potential environmental impacts. EAF slags are highly alkaline and contain constituents of potential concern for human health and waterborne transport. Furthermore, there can be a high degree of variability among slags from different sources. In order to understand the potential environmental impacts of EAF slag utilization in residential landscaping, three as-generated EAF slags and two field-weathered slags were evaluated using EPA’s leaching environmental assessment framework (LEAF). The results of three as-generated slags indicate that the leaching behavior is not related to the total content of constituents. Comparison between as-generated and field-weathered slags indicates that field weathering results in decreased eluate pH, which is known to result from the reaction of alkaline materials with atmospheric carbon dioxide. Based on this comparison, residential use should consider the aqueous leaching behavior over an applicable pH domain of 8 ≤ pH ≤ 13. Aqueous leaching of oxyanions (i.e., As, Cr, Mo, Se) was identified as a potential concern relative to hypothetical screening thresholds for drinking water.

Leaching assessment of electric arc furnace (EAF) slags under residential use

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