Optimização da recuperação da cianita e estaurolita na corrente de rejeitos do circuito húmido não magnético da Kenmare

Abstract

This study, conducted as part of the professional internship for the Bachelor’s degree in Chemical Engineering at Eduardo Mondlane University, aimed to optimize the recovery of kyanite and staurolite from the non-magnetic wet tailings stream at Kenmare. These minerals, which have high industrial value, are currently discarded in large quantities despite their relevance to the refractory and abrasive sectors. Sequential gravity, magnetic, and electrostatic separation techniques were applied, based on the distinct physical properties of the minerals. Chemical analysis was performed using X-ray fluorescence (XRF), and the grades of the target minerals were estimated based on aluminum oxide (Al2O3) content. The results showed that kyanite recovery was unsatisfactory, reaching an estimated final grade of only 13.54%, which is significantly below the 55% threshold required for economic viability. In contrast, staurolite recovery proved highly promising. The optimized flowsheet yielded concentrates with estimated staurolite grades of 87.2% (first electrostatic separation) and 94% (second electrostatic separation). It is important to note that these values, derived from Al2O3 content, represent estimates that require validation through direct mineralogical methods such as scanning electron microscopy (SEM) or X-ray diffraction (XRD). Nonetheless, these results indicate strong potential to achieve the commercially desirable purity range (82–85%), transforming a waste stream into a valuable product. The study concludes that while kyanite recovery is unfeasible with the proposed method, staurolite recovery is technically viable and warrants further efforts toward its concentration.