LI Ning
,
CHEN Jin
,
YAN Hong
,
FENG Xiumei
,
CUI Huijun
,
LIU Jinying
钢铁研究学报(英文版)
To avoid the nonuniform phenomena of heat and mass transfer of metallurgical powdery materials caused by conventional heating method, the temperature rise characteristics of carboncontaining chromite ore fines in the microwave field were investigated using microwave heating in a microwave metallurgical furnace. The experimental results show that the carboncontaining chromite ore fines have better temperature rise characteristics in the microwave field at a frequency of 245 GHz. After heated in the microwave field of 10 kW, the temperature of 1 kg carboncontaining chromite ore fines rose up to 1 100 ℃ in 7 min, at a temperature rise rate of 1571 (℃·min-1·kg-1), whereas the temperature of 1 kg carboncontaining magnetite ore fines rose only up to 1 000 ℃ in 10 min, at a temperature rise rate of 100 (℃·min-1·kg-1). With increasing carbonfitting ratios and by adding calcic lime, their heating effects changed regularly.
关键词:
carboncontaining chromite ore fine;carboncontaining magnetite ore fine;microwave field;temperature rise characteristics
GUO Li-na
,
CHEN Jin
,
ZHANG Meng
,
LIANG Min
钢铁研究学报(英文版)
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, 1226 and 1312 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.
关键词:
gas-solid fluidization
,
high-carbon
,
ferromanganese powders
,
gas decarbonizer
,
solid-phase decarburization
CHEN Jin
,
TIAN Peng-fei
钢铁研究学报(英文版)
Microstructure of solid-phase reduction on manganese oxide ore fines containing coal (MOOFCC) is one of important kinetics conditions of influencing microwave heating. In the condition that an atomic molar ratio of rO: rC in MOOFCC is 1:1.06 as well as a molecular molar ratio of rSiO2: rCaO is 1:1.28, 1 kg of MOOFCC is heated by microwave to reach 1000～1300℃ and hold different time respectively. Experiments show that the metal phase takes the iron-based metal compounds containing manganese as the main content. The manganese content of metal phase increases with the rise of temperature. The partical size of the metal phase is within the range from 0.01 to 0.05mm. MO2 phase in the stuff is entirely changed into MnO phase and the slag phase is mainly composed of wollastonite and manganese olivine. The stuff reduced is loose and massive as a whole with porosity of it from 30 to 45 %. The low softening-melting property and the low density of the stuff impact, to some degree, the solid-phase reduction of powder by microwave heating.
关键词:
manganese oxide ore fines containing coal(MOOFCC);microwave heating;solid phase reduction;microstructure
CHEN Jin
,
WANG Shebin
,
ZHANG Meng
,
LIU Jinying
,
ZHOU Jianxiong
钢铁研究学报(英文版)
The kinetics of voluminal reduction of chromium ore fines containing coal (COFCC) by microwave heating was studied. When the molar ratio of carbon to oxygen was 084 and that of CaO to SiO2 was 039 in COFCC, the temperaturerising rate of COFCC by microwave heating was 625 ℃/min, 6875 ℃/min, 7059 ℃/min, and 7222 ℃/min at 1 000 ℃, 1 100 ℃, 1 200 ℃, and 1 300 ℃, respectively. The results show that the voluminal reduction of COFCC by microwave heating at solidsolid phase is first order reaction, with the apparent activation energy of 51480 kJ/mol. The limiting step of reaction rate for the overall reaction is the mass transfer of CO in the reduced product layer between dielectric particles of chromium ore and coal.
关键词:
kinetics;microwave heating;voluminal reduction;chromium ore fine
CHEN Jin
钢铁研究学报(英文版)
Ionization of gas on carbothermic reduction of metal oxides containing coal by microwave heating is studied in the paper. The result of using the conventional heating method to conduct the carbothermic reduction of metal oxides containing coal is obviously weaker than that of the microwave heating in the term of the reduction time, temperature, atom mole ratio of carbon and oxygen. After studied on the cause, it is believed that gas is ionized in carbothermic reduction of solid-solid phrase between metal oxides and coals, which accelerates progress of carbon gasification and significantly improves kinetic conditions of carbothermic reduction.
关键词:
