Improvement of Refining Method by using Reaction between Multi-component Mesoscopic Phase and Liquid Iron

在介观精炼过程中，与传统的渣精炼相比，无论固液质量比，L的固渣比都较高，脱磷率有了较大提高，理论上降低了渣耗。然而，在介观精炼过程中，只有距离金属/介观相界面约1~2 mm的扩散区对脱磷反应有贡献，而在熔渣精炼过程中，所有的渣都用于精炼过程，并在与金属的界面处形成致密层。因此，向铁水中加入1~2 mm的介观精炼助熔剂是有效的，避免了致密层的形成。由于L的固渣比对温度的依赖性很小，将介观精炼工艺应用于钢的脱磷被认为是有用的。虽然在较高的温度下，渣/渣/金属比变得不利，但提高CaO/SiO_2比可以改善这种情况。在铁水脱磷中，C_2S颗粒是通过液态渣的碳还原析出的，C_2S-C_3P颗粒的大小和分散度与介观相的反应性无关。C_2S沉淀后渣中FeO含量较高，保持渣中FeO的含量很重要。P_2O_5从C_2S-C_3P(C_4P，C_3P)粒子向渣中的还原速率低也是有利的。在目前的精炼过程中，由于助熔剂没有完全熔化，不可避免地要使用大量的助熔剂。在使用混压法制备的介观精炼助熔剂时，由于介观精炼助熔剂的均匀性，精炼效率较高。在采用冷却和/或碳还原技术的沉淀法获得的介观精炼熔剂中，由于固相在介观精炼熔剂中的细小分散，精炼效率较高。

In mesoscopic refining process, the dephosphorization rate is improved considerably due to high L_p^<solid/slag> value irrespective of solid/liquid mass ratio compared with a conventional slag refining, and slag consumption decreases theoretically. However, it is disadvantageous that only the diffusion area of about 1〜2mm length from the interface of metal/mesoscopic phase contributes to the dephosphorization reaction in mesoscopic refining process, while all slag is used in a slag refining process, and the dense layer is formed at the interface with the metal. Therefore, it is effective to inject the 1〜2 mm particles of the mesoscopic refining flux into liquid iron and to avoid the formation of dense layer.Application of the mesoscopic refining process to steel dephosphorization is thought to be useful because of the small temperature dependence of L_p^<solid/slag>. Although L_p^<slag/metal> becomes disadvantageous at higher temperature, it can he improved by increasing CaO/SiO_2 ratio.When the mesoscopic phase, in which C_2S particles precipitate by the carbon reduction of liquid slag, is used in hot metal dephosphorization, the size and dispersion of C_2S-C_3P particles are not related to the reactivity of the mesoscopic phase. It is important to keep the large content of FeO in slag after C_2S precipitation. The low reversion rate of P_2O_5 from the C_2S-C_3P (C_4P, C_3P) particles to slag is also advantageous.In the present slag refining process, large amount of flux is used inevitably because the flux is not completely melted. In the use of mesoscopic refining flux obtained by the mixing-pressing method, the efficiency of refining becomes high because of the uniformity of mesoscopic refining flux. In the use of mesoscopic refining flux obtained by the precipitation method, in which cooling and/or carbon reduction technique is used, the efficiency of refining becomes higher because of the fine dispersion of solid phase in mesoscopic refining flux.