This study evaluates the flocculation performance of six starch-based flocculants—native starch, starch-grafted polyacrylamide (St-g-PAM), anionic starch, cationic starch, and two dual-modified derivatives, anionic starch-grafted polyacrylamide (A-St-g-PAM) and cationic starch-grafted polyacrylamide (C-St-g-PAM)—on real iron ore tailings from four industrial sources representing different mining regions of Iran: North-East, West, Central Plateau, and South. The flocculants, previously developed via a straightforward one-step synthesis method, were assessed in terms of settling velocity, supernatant clarity, and zeta potential of flocs under controlled conditions (solid contents: 0.5–4 wt%; dosage: 80 ppm). Experimental results revealed that dual-modified flocculants consistently outperformed other variants: A-St-g-PAM and C-St-g-PAM achieved the highest settling rates (up to 0.82 cm/s at 2 wt.% solids) and produced supernatant turbidity values below 15 NTU, compared to >80 NTU for native starch. Zeta potential measurements confirmed enhanced particle destabilization, with floc surface charges approaching −20 mV after treatment. Given their facile synthesis route, high efficiency, and biodegradability, these dual-functional flocculants emerge as promising candidates for large-scale industrial dewatering. The findings highlight their potential as environmentally friendly substitutes for conventional synthetic flocculants, particularly in water-scarce mining regions where efficient water recovery and sustainable tailings management are urgent priorities.

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