摘要
The enrichment of chromium in the magnetic iron chromite(Fe(Cr_(x)Fe_(1-x))_(2)O_(4))phase is crucial for the recovery and recycling of chromium in stainless-steel pickling sludge.The kinetics and reaction mechanism of the solid-phase reaction between Fe_(3)O_(4)and Cr_(2)O_(3)were investigated using the diffusion couple method at 1473 K.Not only the diffusion behavior of Fe^(2+)ions and Cr^(3+)ions was elucidated,but also the solid solution behavior of Fe^(3+)ions was discussed clearly.The microscopic morphology of the diffusion couple and the change in the concentrations of Fe and Cr cations across the diffusion layers were analyzed using scanning electron microscopy and en-ergy dispersive spectroscopy.The self-diffusion coefficients of cations were calculated based on the concentration profiles of Fe and Cr,with the results indicating that the self-diffusion coefficient of the Fe ions was consistently higher than that of the Cr ions.Additionally,a mixture of Fe_(3)O_(4)and Cr_(2)O_(3)was annealed at 1373-1473 K for 1-5 h,and the kinetic parameters were calculated by studying the phase content of the product.The phase content of Fe(Cr_(x)Fe_(1-x))_(2)O_(4)in the product was determined by Rietveld refinement of X-ray diffraction data,revealing that an activation energy(E)of 177.20 kJ·mol^(-1) and a pre-exponential factor(B)of 610.78 min^(-1)of the solid-phase reac-tion that produced the Fe(Cr_(x)Fe_(1-x))_(2)O_(4)spinel.
基金
supported by the National Natural Science Foundation of China(No.52274306)
Open Fund of State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology),China(No.SYSJJ2020-03).
