Effect of polycarboxylate superplasticizer on flotation separation of limonite and calcite

Flotation separation of target minerals and gangue minerals has profound significance for the efficient utilization of mineral resources. This study achieved efficient flotation separation of limonite and calcite using sodium dodecyl sulfonate (SDS) as the collector and polycarboxylate superplasticizer (PCE-11) as the inhibitor. The flotation results showed that the separation effect of limonite and calcite was significant at pH 6, SDS concentration of 75 mg/L, and PCE-11 concentration of 40 mg/L, with a maximum flotation difference of 92.86 % between the two minerals. The adsorption quantity test showed that PCE-11 significantly reduced the adsorption quantity of SDS on calcite surface, and the difference in adsorption quantity between limonite and calcite reached 1.0148 mg/g. Zeta potential and infrared spectroscopy analysis indicate that PCE-11 can hinder the adsorption of SDS on calcite surface without significantly affecting the adsorption of SDS on limonite surface, which helps to increase the difference in floatability between limonite and calcite. X-ray photoelectron spectroscopy detection (XPS) analysis demonstrated that PCE-11 selectively hindered the adsorption of characteristic Ca sites on calcite by SDS, but did not affect the adsorption of Fe sites on limonite by SDS. Atomic force microscopy (AFM) detection showed PCE-11 significantly increasing the surface roughness of calcite, slightly increasing the surface roughness of limonite. Therefore, the selective adsorption of PCE-11 on calcite surface hinders the collection of calcite by SDS, increases the difference in floatability between calcite and limonite, and promotes the flotation separation of the two minerals.