Efficient Utilization of Siderite- and Hematite-Mixed Ore by Suspension Magnetization Roasting: A Pilot-Scale Study

Steel is an important industrial raw material and plays an important role in industrial construction. Studying the efficient utilization of complex refractory iron ore with large reserves is of great significance to ensure the strategic safety of China's iron and steel industry. Focusing on the typical mixed iron ore of siderite (FeCO3) and hematite (Fe2O3), this paper analyzes the possible ways of magnetization roasting from the perspective of thermodynamics and highlights that oxidation-reduction roasting is an easy way to realize industrial application. On this basis, a pilot-scale test of suspension magnetization roasting followed by low-intensity magnetic separation is carried out by using a newly developed suspension magnetization roasting furnace. The effects of roasting temperature, CO consumption, and N-2 consumption on the magnetization roasting process are investigated, and 24 h continuous tests are carried out. Here, we find continuous suspension magnetization roasting followed by low-intensity magnetic separation can obtain a total iron grade of over 56% with an average value of 57.18% and a total iron recovery rate of over 91% with an average value of 92.22%. Product analysis shows that after SMR, iron minerals such as siderite and hematite transform into magnetite, with a substantial increase in magnetism, which is conducive to the separation of iron ore. The results provide a reference for the development and utilization of siderite- and hematite-mixed iron ore.