Effect of modifying agents on the removal of impurities in feldspar flotation

The selective separation of feldspar from associated gangue remains a significant challenge in flotation chemistry due to overlapping surface properties especially between feldspars and iron/titanium-bearing silicates. This study investigated the individual, binary, and ternary modifier effects of tannic acid (TA), guar gum (GG), and sodium silicate (SS) on feldspar flotation using froth grade distributions of Al2O3, Fe2O3, TiO2, Na2O and K2O under the light of Fourier-transform infrared (FTIR) spectroscopic responses of floated and non-floated products. Among the individual reagents, GG alone exhibited the highest flotation selectivity, producing concentrates enriched in heavy metal oxides, Al2O3, and K2O with the lowest Na2O grade, whereas its selectivity progressively declined with decreasing GG content in binary mixtures. Froth mass increased with increasing TA dosage; however, its influence on froth modification was constrained by its relatively weak depression efficiency. SS addition increased froth mass while diminishing flotation selectivity by enhancing water entrainment. In binary reagent systems, SS mitigated the modifying effects of both TA and GG, likely due to its non-selective adsorption onto the surfaces of feldspar and floated mineral particles. Binary and ternary reagent systems exhibited both synergistic and antagonistic interactions, governed by modifier type and dosage ratios. FTIR analysis revealed systematic surface modifications arising from the combined adsorption of the tested modifiers, with polysaccharide-dominated ternary systems producing a distinct interfacial structure. The observed spectral changes were closely associated with flotation selectivity and concentrate grades. More pronounced FTIR responses in the non-floated products indicated the preferential adsorption of the modifiers onto the surfaces of the depressed minerals.