复合相炉渣中磷的富集机理研究

In order to improve the slag dephosphorization ability and reduce the slag quantity, steelmaking workers have long been committed to the research of dephosphorization theory, but almost all dephosphorization theory is based on the assumption that the steelmaking slag is homogeneous liquid phase (in fact, the steelmaking slag is multi-phase flux consisted of liquid and solid phase), the solid phase in the slag system have no concern, in which the phosphorus content is several times and even more over than that of liquid phase slag. If we can clarify the enrichment mechanism of phosphorus in multi-phase flux, and give full play to the role of the solid phase, the dephosphorization ability can be greatly increased and the slag quantity can be much reduced, however, due to restriction of research methods and experimental means, the enrichment mechanism of phosphorus in multi-phase flux is still unclear. In this project, the equilibrium phase diagram of multi-phase flux is established for guiding subsequent research work, then the thermodynamic properties of the liquid phase and the solid solution phase in the multi-phase flux are studied by experiments, respectively, according to the research results, the possibility and extent of phosphorus enriched to solid phase are analysis from thermodynamics. Finally, the effects of dynamics factors (such as phosphorus diffusion velocity, the size and morphology of solid particle) on phosphorus enrichment process are investigated, and the dynamic model is established. Based on the studies above, the enrichment mechanism of phosphorus in multi-phase flux is clarified, which innovate the theoretical and method of dephosphorization, and provide scientific basis for reducing lime consumption and the slag quantity during dephosphorization process.

为了提高炉渣脱磷能力和减少渣量，长期以来炼钢工作者一直致力于脱磷理论的研究，但其脱磷理论几乎都建立在假设炼钢炉渣为均匀液相的基础上(实际上炼钢炉渣是液相与固相共存的复合相炉渣)，而对炉渣体系中磷含量是液相渣几倍至几十倍的固相的作用却一直没有任何关注。若能弄清磷在复合相炉渣中的富集机理，充分发挥固相的作用，可大幅提高炉渣脱磷能力和减少渣量，然而受研究方法与实验手段的限制，复合相炉渣中磷的富集机理尚不明确。本项目以建立复合相炉渣的平衡相图为基础指导后续研究，之后通过实验分别对复合相炉渣中液相与固溶体相的热力学性质进行研究，根据研究结果从热力学上分析磷向固相富集的可能性及程度，最后研究动力学因素（如磷的扩散速度以及固体颗粒大小及形貌）对磷富集过程的影响，并建立动力学模型，以达到揭示复合相炉渣中磷富集机理的目标，创新脱磷方法与理论，为减少脱磷过程中石灰消耗与渣量提供科学依据。

为了提高炉渣脱磷能力和减少渣量，长期以来炼钢工作者一直致力于脱磷理论的研究，但其脱磷理论几乎都建立在假设炼钢炉渣为均匀液相的基础上(实际上炼钢炉渣是液相与固相共存的复合相炉渣)，而对炉渣体系中磷含量是液相渣几倍至几十倍的固相的作用却一直没有任何关注。若能弄清磷在复合相炉渣中的富集机理，充分发挥固相的作用，可大幅提高炉渣脱磷能力和减少渣量，然而受研究方法与实验手段的限制，复合相炉渣中磷的富集机理尚不明确。本项目首先调研了少渣冶炼工艺实际炉渣的微观结构与物相组成，之后研究了复合相炉渣的液相与固溶体相中磷的热力学性质以及动力学因素对磷富集的影响，最后通过实验室实验研究了固溶体的两种不同形成机制（析出机制和扩散机制）对脱磷过程中的影响。通过研究发现：少渣冶炼工艺中脱磷期脱磷率较高（40%～60%）的脱磷渣中，磷主要富集在硅酸二钙固相颗粒中；而脱磷率较低（30%以下）的脱磷渣中硅酸二钙固相含量较少，造渣过程中形成富含磷的固相对加快脱磷反应起重要作用；2CaO•SiO2颗粒加入CaO-SiO2-FeO-P2O5体系炉渣后，磷元素在2CaO•SiO2颗粒内均匀分布，渣中酸性氧化物含量(%SiO2)+(%P2O5)达到20%时，FetO含量为70%左右时，磷分配达到最大值，随着渣中2CaO•SiO2颗粒比例增加，磷分配比基本保持不变；当MnO含量低于3%时，固溶体中磷含量随MnO含量增加而降低，当MnO含量高于3%时，固溶体中磷含量随MnO含量增加而增加；加入MgO，Al2O3与Li2O促进了磷向固体颗粒富集；炉渣中固溶体形成有扩散机制与析出机制两种，加入石灰颗粒，固溶体形成机制为析出机制，而加入硅酸二钙颗粒，固溶体形成为扩散机制与析出机制共存，析出机制形成的固溶体含磷量更高；两种机制脱磷实验结果显示，随着C2S固体颗粒量的增加，前3min内脱磷率逐渐降低，从高效脱磷碱度考虑，加入C2S固体颗粒，通过扩散机制难以实现高效脱磷，高效脱磷应控制C2S-C3P固溶体为析出路径。通过本项目的研究揭示了复合相炉渣中磷富集机理，创新了脱磷方法与理论，为减少脱磷过程中石灰消耗与渣量提供了科学依据。