熔融镍渣等温氧化动力学研究

Oxidation Kinetics of Molten Nickel Slags Under Isothermal Conditions

研究了富铁熔融镍渣在空气气氛下的等温氧化动力学行为。利用高温激光共聚焦显微镜(HT-CLSM)确定三元碱度0.6调质镍渣的实际熔融温度(液相线温度)为1488℃。通过管式炉等温氧化试验,获取温度1500~1575℃下熔融镍渣氧化过程Fe^(2+)浓度-时间曲线,采用微分法和Arrhenius方程计算出熔渣中Fe^(2+)的氧化反应级数为1.45~1.26,表观活化能为286.83 k J/mol,明确熔融镍渣氧化动力学主要受扩散传质控速。基于双膜理论和渗透理论,估算出1500~1575℃熔渣中氧的扩散系数分别为2.02×10^(-9)~4.42×10^(-9)m^(2)/s和0.50×10^(-9)~2.19×10^(-9)m^(2)/s,双膜理论估算出的氧扩散系数更具参考意义。

The isothermal oxidation kinetics of iron-rich molten nickel slag in air atmosphere was studied.The actual melting temperature(liquidus temperature)of modified nickel slag was determined to be 1488℃by high temperature confocal laser scanning microscope(HT-CLSM).Variation of Fe^(2+)concentration with time during isothermal oxidation of molten nickel slag was obtained by isothermal oxidation experiment of tubular furnace.The oxidation reaction order of Fe^(2+)in molten nickel slag is 1.45-1.26 and the apparent activation energy is 286.83 kJ/mol by differential method and Arrhenius equation.The oxidation kinetics of molten nickel slag is dominated by diffusion control.Based on the Whitman theory and Higbie theory,the diffusion coefficients of oxygen in the melt are estimated to be 2.02´10^(-9)-4.42´10^(-9)m^(2)/s and 0.50´10^(-9)-2.19´10^(-9)m^(2)/s.The oxygen diffusion coefficient estimated by Whitman theory is of greater reference value.