Enhancing the Reverse Flotation Separation of Ultrafine Apatite and Quartz Using XG-Fe3+ as a Selective Depressant and Flocculant

The separation of ultrafine apatite from quartz through reverse flotation is a challenge due to its low mass and high specific surface area. In this work, xanthan gum–Fe3+ (XG–Fe3+) was explored as a novel and efficient depressant–flocculant for the selective flotation separation of apatite and quartz. The flotation performance and separation selectivity of XG–Fe3+ were systematically assessed using micro-flotation tests. The mechanisms were revealed through turbidity analysis, microscopic observation, contact angle measurement, zeta potential, and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Flotation results illustrated that XG-Fe3+ strongly depressed the flotation of apatite, while it hardly affected the flotation of quartz. Turbidity analysis and microscopic observation indicated the flocculation of fine apatite in the presence of XG-Fe3+, while no flocculation was found for quartz. Contact angle, zeta potential and FTIR results indicated that XG-Fe3+ was chemically adsorbed onto the apatite surface, hindering the adsorption of dodecylamine (DDA) and maintaining the hydrophilicity of apatite. XG-Fe3+ enhanced the flotation separation of ultrafine apatite from quartz by maintaining the hydrophilicity of ultrafine apatite while simultaneously reducing its entrainment into the froth via selective flocculation.