Use of iron ore tailing as raw material for two products: Sodium silicate and geopolymers

In this work, iron ore tailing (IOT) was used for the production of two different materials: sodium silicate and geopolymers. Initially, reactions of IOT with NaOH were carried out by hydrothermal reaction in autoclave at 200 °C (1:1.5 and 1:2.5 SiO₂:NaOH molar ratio) and reaction times of 4 and 8 h. X-ray fluorescence by dispersive energy (XRF), X-ray diffraction (XRD), Mössbauer spectroscopy, scanning electron microscopy (SEM-EDS) and titrations showed that IOT:NaOH ratios of 1:2.5 and reaction time 8 h completely dissolved the quartz from the IOT, obtaining a solid fraction consisting mainly of hematite and an aqueous phase of sodium silicate, which showed contents of ca. 23% SiO₂ and 19% Na₂O. This sodium silicate obtained was then combined with IOT (25 and 50 wt.%) to produce geopolimeric material with excellent physicochemical properties, fast curing time and very good compressive strength results, which ranged from 41 to 58 MPa and many potential applications. (author)