Antimony is a strategic metal defined as a critical raw material by the European Union. One key factor determining the quality of antimony concentrates is impurity levels, with lead (Pb) content playing a particularly restrictive role in both marketability and metallurgical performance. The literature has tested various reagents, such as sodium metabisulfite, polysaccharides, and dichromates, for Pb depression across different ore types and reported their effects on selectivity. At the Eti Bakır Halıköy Plant, periodic increases in Pb grade have been observed, degrading concentrate quality and prompting laboratory- and plant-scale flotation experiments to address this issue. The results demonstrated that among the reagents tested, sodium metabisulfite was the most effective compound for Pb depression. Under laboratory conditions, the Pb content of the antimony concentrate was significantly reduced with the use of sodium metabisulfite. Plant-scale trials similarly showed that the Pb content of the concentrate decreased by nearly half. These findings indicate that sodium metabisulfite is an effective reagent for Pb depression in antimony flotation circuits and that its plant-scale application can improve concentrate quality.