Selective bioflocculation of ultrafine hematite particles from quartz using a biosurfactant extracted from Candida stellata yeast

In the last decade the mineral industry has been working in order to face its biggest challenge: The processing of ultrafine mineral particles. Several techniques and processes have been used to improve its recovery, without success. Bioflocculation has been considered as a potential tool in order to process these particles. The aim of the present study was to evaluate the flocculation of ultrafine hematite particles contained in iron ore tailing slimes, using the biosurfactant (BS) extracted from the Candida stellata yeast. The analysis of the mineral-biosurfactant interaction was conducted through FTIR spectroscopy, zeta potential, and surface tension measurements. The flocculation analysis was made using a laboratory jar-test. The FTIR and zeta potential investigations indicated adsorption of the BS onto hematite surface. The biosurfactant modified the surface properties of hematite and a reversal charge point was observed at pH 3.3. Thus, bioflocculation of pure hematite particles (recovery of around 90%) was conceivable under pH 3.0, and using between 75 and 100 mg.L−1 of BS. Lastly, bioflocculation of the tailing slimes sample was conducted: The previous results were confirmed, which means that a selective flocculation was pointed out at pH 3.0, achieving an iron recovery and grade of around 92% and 59%.