Abstract: Investigation was made on the magnetization of 40~60 μm Daxigou siderite powder by roasting in suspension state to study the law of influence of roasting temperature, time and atmosphere on the quality of the roasted product. The result indicates that temperature is the primary factor influencing the roasting process, the time needed for perfect roasting decreases with the increase of the roasting temperature. With the oxygen increase in the roasting atmosphere, the product quality degrades because of oxidation. Prior to the complete decomposition of siderite, the FeCO₃ decomposition is the essential factor influencing the roasting effect and a time prolonging would be beneficial to improving the product quality. After the siderite is fully decomposed, oxidation degree will be the main factor influencing the roasting effect and a roasting time increase would lead to a reduced product quality. The product from the suspension roasting of Daxigou siderite powder in a suspension state in a weak oxidation atmosphere with 1.05% oxygen concentration at 800 ℃ or 850 ℃ for one minute can be treated by magnetic separation to obtain a concentrate grading 58.21% iron or higher at an iron recovery no less than 79.39%.

Key words: Siderite, Suspension state, Magnetic roasting