Chromite ore addition to serpentinized magnesite mining wastes for the production of refractory products following thermal treatment

Abstract

Taking a circular approach to mining facilities requires the further exploitation of produced solid wastes, which are now considered as potential raw materials. This research aims to the re-utilization of specific mining wastes, containing mainly geologically degraded serpentinized minerals, produced during the minerals’ enrichment process of extractive magnesite industry, combined with the addition of chromite ore, aiming to the upgrading of refractory properties of the product, by applying the appropriate thermal treatment. A representative sample examined, corresponding to the proper blending of different mineral waste samples from several waste piles of mining area, combined with various chromite ore’s content, followed by the investigation of optimum thermal treatment, considering the applied temperature and time. The scope was to maximize the (desired) forsterite mineral phase in the product and, hence, to improve its refractory properties. The optimum results (e.g., considering the firing shrinkage level and the mechanical strength) achieved by the application of thermal treatment at 1300 °C and after heating time for 120–240 min. The refractory properties generally improved after mixing of examined mining wastes and chromite ore, due to the achievement of the best molar ratio of constituents [MgO]/[SiO2] = 2.2, regarding the additive, enhancing the formation of forsterite, whereas the application of heating temperatures over 1300 °C led to the melting of enstatite mineral phase, resulting to the degradation of product. The obtained results reveal that the produced sintered products can exhibit better refractory properties, and can be used as refractory raw materials for relevant applications up to 1300 °C.