Updating mechanism of siderite roasting through insights into reactions between inherent oxides of iron and carbon

The roasting of siderite (FeCO3) was investigated to clarify the reaction mechanism in inert atmosphere using micro fluidized bed reaction analyzer coupled with on-line particle sampling (MFBRA-P). Thermodynamic results indicated that the reactions of 6FeO + CO2 → C + 2Fe3O4 and 3FeO + CO → C + Fe3O4 are both possible to occur in the transformation process of siderite to Fe3O4. The presence of C was identified in the final solid product through analysis scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and calcination experiment of product sample in the atmosphere containing O2. Combining thermodynamic and experimental results, an updated reaction mechanism of siderite roasting in inert atmosphere was proposed. The siderite is first decomposed to form FeO and CO2, and in turn FeO rapidly reacts with CO2 to form Fe3O4 and CO. Meantime, the released CO2 or CO during decomposition reacts with FeO to form C and Fe3O4.