Heavy Metals Environmental Fate in Metallurgical Solid Wastes: Occurrence, Leaching, and Ecological Risk Assessment

The metallurgical industry generates substantial amounts of heavy metal-containing solid waste, posing significant environmental and health risks. This study systematically evaluates the environmental behavior and ecological risks of heavy metals in four typical metallurgical wastes: jarosite slag (SW1), electric arc furnace ash (SW2), chromium-containing sludge (SW3), and acid-base sludge (SW4). We demonstrate that particle size fundamentally governs heavy metal mobility, with fine-structured SW1 and SW2 (D₅₀ = 4.76 µm and 1.34 µm) exhibiting enhanced metal mobility and bioavailability. In contrast, coarser SW3 and SW4 particles (D₅₀ = 268.83 µm and 133.94 µm) retain heavy metals in more stable forms. Among all metals analyzed, cadmium (Cd) presents the most severe ecological threat, with acid-extractable fractions reaching 52% in SW2 and 45% in SW3-indicating high release potential under changing pH conditions. Risk assessment confirms high to very high ecological risks for Cd in both SW2 and SW3. Moreover, under acidic leaching conditions, SW1 and SW2 show significantly higher cumulative toxicity than SW3 and SW4. These findings highlight the critical role of waste-specific properties in controlling heavy metal fate and provide a scientific basis for targeted risk management and sustainable remediation strategies.