Thermodynamic conditions of reactions between high-carbon ferromanganese powders and gas decarbonizers like O2, CO2 and water vapor were studied by thermodynamic calculation. In O2, CO2 and water vapor atmosphere, high-carbon ferromanganese powders were decarburized in a fluidized bed. When the temperature is respectively higher than 273, 1 226 and 1 312 K, the gas-solid decarburization reaction will occur between ferromanganese carbide on the surface of the high-carbon ferromanganese powders and different gas decarbonizers. Since metal manganese is easy to be oxidized by O2, CO2 or water vapor, the decarburization reaction will transfer into a solid-solid phase reaction of ferromanganese carbide and ferromanganese oxide, promoting external diffusion of carbon to achieve a further decarburization of high-carbon ferromanganese powders.
Solid-phase decarburization of high-carbon ferromanganese powders （HCFPs） was conducted using calcium carbonate powders （CCPs） as a decarburizer by microwave heating. Solid-phase decarburization kinelSics was investi- gated by isothermal method. The results show that the HCFPs show excellent microwave absorption at a higher av- erage heating rate of 80 ℃/min, while CCPs exhibit poor microwave absorption at a lower heating rate of 5--20 ℃/min; the heating characteristics are in-between when HCFPs and CCPs are mixed. The average heating rates of the mix- ture are 32.14, 31.25, 31.43, and 30.77 ℃/rain when the mixture is heated up to 900, 1000, 1100, and 1200 ℃, respectively. The good microwave absorption property of the mixed material lays the foundation for the solid-phase decarburization of HCFPs containing CCPs. Solid-phase decarburization of HCFPs containing CCPs is a first-order reaction by microwave heating. Apparent activation energy of solid-phase decarburization is 55.07 kJ/mol, which is far less than that of ordinary carbon gasification reaction and that of solid-phase decarburization under the same de- carburization condition by conventional heating. It indicates that microwave heating not only produces thermal effect, but also has non-thermal effect.
The solid-phase decarburization of high-carbon ferromanganese powders （HCFPs） was investigated using calcium carbonate as the decarburizer by microwave heating and conventional heating methods to explore the differ-ences of microwave heating and conventional heating. Experimental results show that HCFPs containing calcium.car-bonate were heated up to 900, 1000, 1 100, and 1200 ℃ and held for 60 rain for decarburization by microwave heat-ing at decarburization ratios of 76.69%, 82.90%, 84.11%, and 85. 75%, respectively. These ratios are higher than the decarburization ratios used for conventional heating under the same experimental conditipns. The microwave heat- ing can significantly improve decarburization ratio. This indicates the microwave heating field features a non-thermal effect, which in turn, visibly enhances the carbon diffusion ability of HCFPs. It also improves the kinetic conditions of solid-phase decarburization.
GUO Li-naCHEN JinSHI Wen-liZHAO JingLIU KeLIU Jin-ying
