硫化亜鉛の窒素気流下における金属鉄による還元揮発反応速度

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Zinc sulfide is directly reduced to zinc gas with metallic iron. In such a reaction the sulfur is fixed as pyrrhotite, and then it would be expected that roasting and/or sintering zinc sulfide would not be required. From this point of view, reaction experiments of zinc sulfide reduction with metallic iron have been conducted under nitrogen stream in the temperature range of 1,180∼1,240 K. A shrinking unreacted-core model has been applied to analyze the reaction data, based on the observation of cross section of partially reacted sample. In the model, the following steps were considered: a chemical reaction, a diffusion of zinc gas away through the product layer, and a diffusion of zinc gas through gas film. Reaction rate constant kc and effective diffusivity De determined were expressed as follows: kc/mol·m-2·s-1 = exp {-124.9 × 103/(RT) + 6.386} De/m2·s-1 = exp (-58.57 × 103/T + 37.41) where R : gas constant (J·mol-1 ·K-1 ), T : temperature (K). The activation energy of the reaction was 125 kJ·mol-1 . The calculated reduction curves using the rate parameters obtained finely reproduced the experimental data. The reaction proceeds faster with increasing temperature. The reaction is controlled by the diffusion of zinc gas away through the product layer at a lower temperature, while at a higher temperature, both the diffusion of zinc gas away through the product layer and the chemical reaction determine the reaction. At temperature of only 60 K higher, the reaction rate of zinc sulfide with metallic iron under nitrogen stream was comparable with that under vacuum.
社団法人資源・素材学会の論文
1998-09-25

硫化亜鉛の窒素気流下における金属鉄による還元揮発反応速度

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