Investigations on the Barium-Bearing Magnetite Concentrate Roasted in Air

To expand the application of barium-bearing magnetite in pellets, the oxidation induration mechanism for barium-bearing magnetite concentrate pellets with the BaSO4 contents from 0 to 8wt pct as an additive was investigated in this paper. The green pellets were preheated at 900 °C for 10min and roasted at 1200 °C for 20min.The XRD, SEM-EDS, and TG were used to systematically analyze the phase composition, microstructure, elemental distribution, and oxidation behavior of the pellets with the different contents of BaSO4. The results indicated that BaSO4 reacted with SiO2 and Fe2O3 to form BaSiO3 and BaFe2O4, respectively. When the content of BaSO4 was less than 2 wt pct, the Ba-bearing silicate filled the hematite grains, which promoted the induration process of the pellets. With a further increase in the amount of BaSO4, the growth of hematite grains was suppressed by the Ba-bearing silicate. In addition, the BaFe2O4 distributed along the hematite grains’ boundaries, and the SO2 that decomposed from BaSO4 separated out from the pellets, which led to a decrease of compressive strength. Thereby, the compressive strength decreased, the porosity increased. A schematic of the oxidation induration mechanism is also presented based on the experimental results, providing the theoretical and technical foundations for the use of Ba-bearing oxide minerals in pellets.