Enhancing sustainability in phosphate ore processing: Performance of frying oil as alternative flotation collector for carbonate removal

Recycling waste frying oils for the synthesis of flotation reagents presents a promising avenue for sustainable waste management. Moreover, it offers a cost-effective solution for crafting a specialized collector designed to efficiently remove carbonates and enhance phosphate enrichment in froth flotation processes. This study focuses on the synthesis of an anionic collector using the saponification reaction of a frying oil sample, subsequently applied to the flotation of calcite and dolomite. To elucidate the adsorption mechanisms of the frying oil collector (FrOC) and sodium oleate, a reference collector, on fluorapatite, calcite, dolomite, and quartz surfaces, comprehensive experiments were conducted, including zeta potential measurements and Fourier transform infrared spectroscopy. Results revealed diverse adsorption affinities of the molecules towards these minerals. To assess the practical performance of the collector, flotation tests were conducted using a natural phosphate ore mixture, employing a Box-Behnken experimental design. Notably, under optimized conditions (pH 9, 1000 g/t of FrOC, 3.5 min of conditioning, and 6 min of flotation), FrOC exhibited excellent performance, with calcite and dolomite recoveries exceeding 80%, while apatite recovery in the concentrate fraction remained below 10%. This work exemplifies both circular economy practices and the distinctive approach to sustainable mineral processing.