Ion–mineral interactions and soybean-based collector for sustainable phosphate ore flotation at natural pH

Phosphate ore flotation is strongly affected by ion–mineral interactions, particularly with calcium and magnesium ions, which influence collector adsorption and mineral recovery. In this study, the flotation of phosphate ore was systematically investigated at natural pH, integrating mechanistic insights with process optimization for sustainable beneficiation. Flotation experiments on pure apatite demonstrated that elevated Ca2+ and Mg2+ concentrations suppress collector adsorption, leading to depressed flotation performance. Fourier transform infrared (FTIR) spectroscopy confirmed that competitive cation adsorption disrupts collector binding on the apatite surface. Building on these mechanistic findings, flotation tests on real ore were optimized using a Design of Experiments (DOE) methodology. Collector dosage, solids concentration, and pulping time were identified as the key operating variables controlling recovery. Under the optimized conditions, the process achieved a P₂O₅ grade of 23.16 % demonstrating significant improvement over the raw ore. Importantly, all experiments employed a soybean-derived collector, eliminating the need for chemical pH adjustment and reducing dependence on synthetic reagents. This bio-based reagent system achieved improved flotation performance while addressing sustainability challenges in phosphate processing. The combined mechanistic and process-level insights highlight the dual benefits of understanding fundamental mineral–ion interactions and implementing green reagent strategies. Overall, this work provides both theoretical and practical guidance for the development of environmentally friendly phosphate beneficiation processes aligned with circular economy and sustainable mineral engineering principles.