Supposing to utilize the slag with high P₂O₅ content as a new phosphorus resource produced from a novel steelmaking process, a fundamental investigation was carried out with particular focus on spontaneous liquid-liquid phase separation occurring in the system CaO–P₂O₅–FeO for effective phosphorus recovery. At 1773 K, two types of phase separation, which is a double-layered or a dispersed structure of two liquid phases, were observed according to the bulk composition. The double layers separated vertically and consisted of the phase with higher P₂O₅ content over 40 mass%, and the phase with higher FeO content over 90 mass%. Such structure corresponds to the liquid-liquid separation in the compositional region which is located in higher P₂O₅ content (upper side) against the tie line between Ca₃P₂O₈–FeO apex on the isothermal section of CaO–P₂O₅–FeO ternary system. At 1673 K, various separation was observed such as a double-layer or a dispersed structure of two liquid phases, and a coexistence of solid/liquid phases. The slag with the bulk composition lying in the upper two liquid region showed the double-layered structure, giving a promising result for phosphorus recovery through phosphate concentration. The condition for formation of double-layered structure was considered based on the index originally proposed for co-continuity in polymer blends processing, which consists of viscosity and volume fraction of the co-existing phases. The index was found to represent a specific condition for making co-continuous phases in this study and would be significant in view of effective phosphorus recovery.

_{为了利用高P 2} O ₅含量的炉渣作为新型炼钢工艺产生的新磷资源，对CaO-P ₂ O ₅体系中发生的自发液-液相分离进行了基础研究。–FeO 可有效回收磷。在 1773 K 时，根据本体组成观察到两种类型的相分离，即两种液相的双层或分散结构。双层垂直分离，由P ₂ O ₅含量高于40质量％的较高相和FeO含量高于90质量％的相组成。这种结构对应于成分区域中的液-液分离，该成分区域位于较高的P ₂ O _{5含量（上侧），相对于CaO-P 2}等温截面上Ca ₃ P ₂ O ₈ –FeO顶点之间的联络线O ₅ –FeO三元体系。在 1673 K 时，观察到各种分离，例如两个液相的双层或分散结构以及固/液相共存。大部分成分位于上部两个液体区域的炉渣呈现出双层结构，为通过磷酸盐浓缩回收磷提供了良好的结果。基于最初提出的聚合物共混加工共连续性指标，考虑了双层结构的形成条件，该指标由共存相的粘度和体积分数组成。发现该指数代表了本研究中形成共连续相的特定条件，并且对于有效磷回收而言具有重要意义。