Alkaline Hydrothermal Treatment for Model Compounds of Gangue Components Present in Iron Ore

Abstract

To elucidate the removal mechanism for gangue (Al, Si, and P elements) components in low-grade iron ore using an alkaline hydrothermal treatment, model compounds of the gangue components were treated with a 5M NaOH solution using a bath-type reactor. The effective removal of P ions by alkaline treatment at room temperature suggests that these ions are desorbed from α-FeOOH. The Si and Al contained in SiO₂ and kaolinite can also be removed by alkaline hydrothermal treatment, and the extent of removal increases following washing. Na forms compounds with clay minerals and this is inferred to be the cause of the residual Na detected following treatment. The presence of α-FeOOH and Fe₂O₃ is found to have almost no effect on this residual Na content. P in Fe-P compounds can also be removed by alkaline hydrothermal treatment.