Soda-Ash Roasting Behavior of Ludwigite Ore Under Different Oxygen Concentrations

Efficient and comprehensive utilization of the ludwigite oreLudwigite ore in China has an important strategic significance. However, the significant challenge is the development of highly efficient boron and iron separation process. Soda-ash roastingSoda-ash roasting proves to be a facile approach for boron activation and extraction, wherein magnetite frequently was converted to hematite, which affects the subsequent recovery of iron. This work investigated the phase transformations, microstructure evolutionMicrostructure evolution and magnetism changes of soda-ash roasted ludwigite oreLudwigite ore under different O2 concentrations at 1123 K. Results indicate that Fe3O4 was not obviously oxidized to Fe2O3 but reacted with MgO to form MgxFe3−xO4 and MgyFe1−yO, when the O2 concentration is not more than 5.0 vol%. As the O2 concentration further increased, Fe3O4 was converted to Fe2O3 and MgFe2O4.