An efficient process to upgrade siderite ore by pre oxidation-magnetization roasting-magnetic separation-acid leaching

Abstract

In this paper, a process of pre-oxidation and magnetization roasting followed by low-intensity magnetic separation and acid leaching (OMLA) was developed to separate and recover iron from siderite ore with high-magnesium and high-manganese. The pre-oxidation of siderite ore was performed in a tube furnace at 800 °C for 45 min, improving the iron recovery by 6%. The effects of conditions of magnetization roasting, magnetic separation and acid leaching on the separation indices were studied. Under the optimum parameters, the iron concentrate, assaying 62.01% Fe, 8.74% MgO, 2.41% MnO with comprehensive recovery of 96.9%, were obtained through the OMLA process. Phase and microstructure transformation of the samples in OMLA process were investigated by SEM-EDS. The results indicated that pre-oxidation of siderite ore can cause porous structure of raw sample, improving reduction efficiency in magnetization roasting process. Most of gangue minerals (dolomite, ankerite, quartz and muscovite) could be removed in the process while Mn and part of Mg which existed in the iron oxides in the form of isomorphous substitution throughout the OMLA process would remain in the final concentrate.

Keywords

• Siderite ore
• Magnetization roasting
• Magnetic separation
• Acid leaching
• Pre-oxidation
• Manganese