Selective Recovery of Molybdenum from Steelmaking Dust Leachate Using Cyanex 600

Steelmaking dust generated by steelmaking processes contains significant concentrations of heavy metals, classifying it as a hazardous waste that industries must handle. Among these, molybdenum (Mo) plays a critical role in modern technologies. Its increasing demand, coupled with concerns about long-term resource sustainability, has driven growing interest in recovering Mo from secondary sources. Selective Mo leaching was first achieved using 0.05 M NaOH, retaining Fe and Zn in the solid residue while partially dissolving Cr. Subsequent solvent extraction with Cyanex 600 enabled selective Mo extraction over the pHeq range 2–4. Investigation of the extraction mechanism revealed that phosphine oxide impurities in the extractant enable neutral extraction of Mo and Cr. Given the versatility of steelmaking dust composition, the presence of Zn in real-life leaching solutions cannot be neglected, and another Zn-containing feed was evaluated. With Zn present, selective Mo extraction was possible under the following conditions: [Cyanex 600] = 0.1 M, t = 10 min, pHeq = 1.4, and T = 20°C. McCabe-Thiele (MCT) analysis revealed that 3 countercurrent stages would be necessary to extract 99% of Mo at an organic to aqueous ratio (θ) = 0.25. Finally, a solution containing 1.4 g/L Mo could be produced after stripping with 0.15 M NH4OH.