Function Mechanism of Sodium Sulfate Additive on Iron Carbide Preparation with Low-Grade Siderite

The carburization roasting treatment followed by the magnetic separation is an effective way to utilize low-grade siderite, in which the sodium sulfate additive plays an important role. In order to investigate the role of sodium sulfate additive, the present study fixes its particular attention on the function mechanism of sodium sulfate additive during the preheating treatment, carburization, and separation process. The results show that sodium sulfate additive can enhance the oxidation, reduction, and carburization reactions of siderite pellet, which dramatically increases the carburization rate and degree of siderite pellet. Besides, sodium sulfate additive can significantly improve the growth of iron carbide particle, transform the dense gangue into loose gangue, and produce the cracks inside pellet, which greatly promotes the separation of iron carbide and gangue. In the whole process, preheating treatment at high temperature is a necessary process to intensify and maintain the additive’s effects.