Characterization of Serpentinite Reject from HPAL Technology for Refractory and Construction Use

Abstract

The serpentinite material rejected in the ore preparation plant of the nickel company Moa-Nickel S.A. constitutes a solid mining-metallurgical environmental liability with potential for revalorization. The purpose of this research was to characterize the physical, chemical, mineralogical, and thermal properties of the serpentinite reject in order to assess its potential as a raw material for construction and refractory applications. Dry sieving (ASTM C136), atomic absorption spectrometry, X-ray diffraction, and thermal analysis tested samples obtained with the cones and rings method. The results showed that approximately 24 % of the reject, corresponding to         the −3.33 mm +1.4 mm fraction, can be used as aggregate for concrete and pavements, while about 20 % of the fine fractions smaller than 1.4 mm is of interest for refractory applications such as molding sands and refractory paints. Magnesium oxide (33.20 %) and silicon dioxide (29.16 %) predominated, with an MgO/SiO₂ ratio of 1.14 that imparts a basic character to the material. The main phases identified were serpentine (lizardite and chrysotile), forsterite‑rich olivine, and kaolinitic clays. Thermal analysis revealed a mass loss of 4 % associated with the removal of hygroscopic water (up to 260 °C) and a 12 % loss corresponding to the dehydroxylation and recrystallization of serpentine and olivine minerals (390 °C–825 °C), supporting its use as a refractory material.