Phase transformations of siderite ore by the thermomagnetic analysis data

Thermal decomposition of Bakal siderite ore (that consists of magnesium siderite and ankerite traces) was investigated by thermomagnetic analysis. Thermomagnetic analysis was carried-out using laboratory-built facility that allows automatic registration of sample magnetization with the temperature (heating/cooling rate was 65°/min, maximum temperature 650°C) at low- and high-oxygen content. Curie temperature gradually decreases with each next cycles of heating/cooling at low-oxygen content. Curie temperature decrease after 2nd cycle of heating/cooling at high-oxygen content and do not change with next cycles. Final Curie temperature for both modes was ~320°C. Saturation magnetization of obtained samples increases up to 20Am2/kg. The final product of phase transformation at both modes was magnesioferrite. It was shown that intermediate phase of thermal decomposition of Bakal siderite ore was magnesiowustite. •Mg-siderite decomposition was investigated by thermomagnetic analysis.•Magnetization and Curie temperature change with each next cycle of heating/cooling.•Magnesioferrite is the final phase of Mg-siderite thermal decomposition.•Transformation exclude the hematite formation.