Lixiviação do pirocloro e finos de liga Fe-Nb para obtenção do óxido de nióbio de alto teor

Abstract

The present work aimed to develop and propose at least one route for producing niobium oxide of purity above 98.5%, through the leaching of impurities contained in the pyrochlore concentrate and/or niobium leaching from Fe-Nb alloy fines. Two processing routes were evaluated, being one of these routes for the pyrochlore concentrate the proposed adaptation presented in the literature for a tantalite-columbite concentrate and the other route (for Fe-Nb alloy fines) based on studies of the thermodynamic behavior of niobium in hydrometallurgical processes and corrosion studies of the Fe-Nb alloy. The route for the pyrochlore concentrate presented problems due to the formation of a cohesive and resistant aggregate that reduced the surface area of contact and influenced the alkaline leaching stage, hindering an efficient removal of the silicon and magnesium contaminants. The total content of those elements overpassed 2%, that dificults to obtain a product with 98,5% of Nb2O5. The study of this route requires na additional step of cominuttion that was not carried out in the present study due to dproblems during the pandemic of Covid_19. It was prioritized the route for the Fe-Nb alloy fines that proved to be promising in the formation of niobium compounds (potassium niobate, niobium acid and the final product niobium oxide), had an acceptable yield and reached the quality target with a 98.5% niobium oxide content.