Selective flocculation-magnetic separation of ultrafine ilmenite regulated by sodium polystyrene sulfonate and sulfonated polyacrylamide

The preconcentration of ultrafine ilmenite through magnetic separation has been a major technical challenge in mineral separation. Selective flocculation aggregates fine target minerals, enhancing their magnetic capture efficiency under low field strength. In this study, sodium hexametaphosphate (SHMP) was used as dispersant, while sodium polystyrene sulfonate (PSSNa) and sulfonated polyacrylamide (PAMS) served as the flocculants. Flocculation-sedimentation and flocculation-magnetic separation experiments were conducted to assess the effects of reagent dosage, pH, and magnetic field intensity on the flocculation efficiency of ultrafine ilmenite. The results revealed that PAMS exhibited non-selective flocculation toward both ilmenite and gangue minerals, while pre-addition of PSSNa effectively suppressed the PAMS-induced aggregation of gangue minerals. At dosages of 2000 g/t PSSNa and 10 g/t PAMS, the TiO 2 grade and recovery increased by 1.77% and 8.06%, respectively, compared with the system containing only SHMP. Mechanistic investigations through zeta potential, EDLVO theory, and X-ray photoelectron spectroscopy (XPS) indicated that in the absence of reagents, hetero-coagulation between ilmenite and gangue minerals predominated. PSSNa preferentially binds to Fe 3+ , Ca 2+ , and Mg 2+ sites on the surfaces of gangue minerals, regulating subsequent PAMS adsorption and enhancing flocculation selectivity. This study proposes a mechanism of PSSNa-PAMS for ultrafine ilmenite separation, providing new insight into interface chemistry control in selective flocculation-magnetic separation processes.