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

在介观精炼过程中，无论固液质量比如何，由于L_p^<固渣>值较高，脱磷率较常规渣精炼有较大提高，理论上耗渣量降低。然而，在介观精炼过程中，只有距离金属/介观相界面约1 ~ 2mm的扩散区域有助于脱磷反应，而在渣精炼过程中全部使用渣，并且在与金属的界面处形成致密层。因此，将介观精炼助熔剂的1 ~ 2mm颗粒注入铁液中，可有效避免致密层的形成。由于L_p^<固/渣>对温度的依赖性小，介观精炼工艺在钢脱磷中的应用被认为是有用的。虽然L_p^<渣/金属>在较高温度下是不利的，但通过提高CaO/SiO_2比可以改善。采用液渣碳还原析出C_2S颗粒的介观相进行铁水脱磷时，C_2S- c_3p颗粒的大小和分散性与介观相的反应活性无关。在C_2S沉淀后，炉渣中FeO的含量保持在较高水平是很重要的。P_2O_5从C_2S-C_3P （C_4P, C_3P）颗粒到炉渣的低还原率也是有利的。在目前的渣精炼工艺中，由于熔剂未完全熔化，不可避免地要使用大量的熔剂。在使用混压法得到的介观精炼助熔剂时，由于介观精炼助熔剂的均匀性，提高了精炼效率。在采用冷却和/或碳还原技术的沉淀法得到的介观精炼助熔剂中，由于固相在介观精炼助熔剂中分散较好，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.