动态氧化条件下含钛高炉熔渣中钙钛矿析出与长大机理

Precipitation and growth mechanism of perovskite phase in molten Ti-bearing blast furnace slag under dynamic oxidation condition

  • 摘要: 动态氧化不仅有利于含钛高炉熔渣中钛组分富集于设计相(钙钛矿相),同时还会促进钙钛矿相析出与粗化,在自然重力作用下粗化的钙钛矿实现重力富集与沉降分离.本文运用玻璃形成动力学方程,对动态氧化条件下含钛熔渣中钙钛矿相形核速率和晶体生长速率进行分析和研究.结果表明,向熔渣鼓入氧气,低价钛逐渐氧化为四价钛,促进钙钛矿析出反应的进行,提高了钙钛矿晶体生长速率.继续通入氧气则氧化时间过长,熔渣中高熔点TiC和TiN固体颗粒基本消失,黏度降低,异相形核转化为均相形核,析出温度显著降低,析晶温度区间缩短,不利于钙钛矿晶粒粗化和长大.

     

    Abstract: Dynamic oxidation is not only in favor of that Ti components in molten Ti-bearing blast furnace slag enrich into the design phase (perovskite), but also promotes the coarsening and growth of perovskite phase. The enrichment and settlement of coarsened perovskite are carried out under the action of gravity. The nucleation rate and the crystal growth rate of perovskite phase in molten Ti-bearing blast furnace slag under dynamic oxidation condition were studied by using the kinetic equation of glass formation. The results show that low valence titanium (Ti2+) and (Ti3+) are oxidized to (Ti4+) under dynamic oxidation condition by blowing oxygen, which can promote the precipitation of perovskite and increase the crystal growth rate. When continuing to blow oxygen, the oxidizing time would be too long, TiC and TiN particles decrease and finally almost vanish, the slag viscosity decreases, and the crystallization of perovskite phase transforms from heterogeneous nucleation into homogeneous nucleation. As a result, the precipitation temperature decreases and the precipitation temperature range shortens, which restrain the coarsening and growth of perovskite.

     

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