A pH-Responsive flavylium surfactant as a recyclable hydrophobic modifier for selective aggregation and flotation of kaolinite

Amidst increasing environmental concerns and the limitations associated with conventional synthetic reagents, the advancement of sustainable and efficient alternatives has emerged as a significant priority in mineral processing applications. In the present study, a bio-molecule-based hydrophobic modifier was introduced as a previously unreported kaolinite collector for the froth flotation separation of kaolinite from calcite. Synthetic yttrium-loaded kaolinite (kaol-Y) was used in single mineral flotation tests, with yttrium serving as a proxy for rare earth elements (REEs). This approach aimed to assess the collector's effectiveness in ionic clay systems containing REEs. Spectroscopic techniques were used to analyze selective adsorption, while the selective aggregation of kaolinite under high shear conditions was evaluated using an image-derived particle size measuring technique, providing insights into particle aggregation under dynamic fluid environments. The impact of collector dosages on separation performance was systematically evaluated through lab-scale mechanical flotation cell experiments. The optimal dosage was determined to lie within the range of 0.2-0.4% wt, resulting in a separation process that achieved over 90% kaolinite recovery in the concentrate at a grade of 70%, starting from a feed grade of 50%. The pH-responsive nature of the collector facilitated the recovery of the reagent from the concentrate, effectively demonstrating a recycling strategy that provides a cost-effective and sustainable solution for kaolinite flotation. This approach, employing bio-inspired collectors, holds significant promise for ongoing advancements and further optimization in flotation processes. • Selective clay surface modification by alkyl amine functionalized flavylium • Kaolinite separation from calcite by froth flotation using amphiphilic flavylium as a hydrophobic collector • Post-flotation recovery of stimuli-responsive flavylium surfactants • Recyclability and re-use of pH-responsive flavylium compounds in a froth flotation system to demonstrate sustainability