Papers by Keyword: Magnetizing Roast

Abstract: In this paper, the reaction kinetic mechanism of Fe₂O₃ powder containing carbon was studied by microwave magnetizing roast. Based on the temperature-rise curve and weight loss curve of Fe₂O₃ powder by microwave magnetizing roast, the kinetic parameters of Fe₂O₃ powder microwave magnetizing roast were calculated by non-isothermal methods. The controlling steps of different temperature-rising periods in microwave magnetizing roast process of Fe₂O₃ powder were calculated by the Achar-Brindley-Sharp-Wendworth method. The results indicated that the controlling step of microwave magnetizing roast was phase boundary reaction control of contracted cylinder in 250~450°C, and it was three-dimensional diffusion control of spherical symmetry in 450~650°C. The results showed that the starting temperature of reduction roasting of Fe₂O₃ powder was 250°C, which was lower than that under electrical heating, thereby, it proved in theory that microwave heating can enhance reaction rate.

Abstract: Along with the continuously rose of the iron ore price and the Chinese iron ore quantity demanded, Iron ore self-sufficient rate has become the bottleneck of Chinese steel industry development. In order to increase Chinese ore self-sufficiency rate, the paper study the xinjiang region low grade specularite. When the crude ore grade is 35%, the mass percent of reducing agent pulverized coal is 12%, roasting temperature is 800°C，roasting time is 50 min, milling fineness is 90% passing 0.074 mm and the magnetic induction is 84kA/m, after a low intensity magnetic separation, the iron concentrate can be got whose yield is 42.83%, grade is 62.04% and recovery is 79.26%.

Abstract: In this article, the microwave magnetizing roast process of three kinds of Bayan Obo ore of different Fe-grades were studied experimentally, where microwave as the heat source and the activated charcoal as reductant. The reduction characteristics of hematite changed into magnetite by microwave magnetizing roast were studied analytically under different experimental conditions, where magnetisability and percent reduction of roasting ores as measure.It showed that under the optimum conditions of microwave roasting of hematite (the theoretical carbon content, the microwave voltage of 220V, the temperature of 650 °C and the heat preservation time of 10min), magnetisability and percent reduction of hematite were best , close to the theoretical value of 2.33 and 11.11% respectivly. And after the first weak magnetic separation of microwave roasting ores , the recovery of iron were all above 90%, which indirectly showed that the microwave reducing roasting magnetization effect were very good under the conditions. The Fe-grades of iron concentrate may achieve above 60% after the second magnetic separation ,which met the requirement of iron-making.