PURPOSE: To improve the softening properties of pellets at high temp. by forming each pellet with a basic core part having a specified iron content or above and a specified basicity value or below and a shell part satisfying 2 conditions of basicity and MgO content in a region above a specified temp. in specified melt-producing isothermal curves.
CONSTITUTION: Baic pellets for iron manufacture are formed with fine iron ore as starting material. Each core part has ≥64% iron content and ≤1.9 basicity represented by CaO/SiO2. Each shell part is allowed to satisfy 2 conditions of the ratio of CaO/SiO2 and MgO content in a region above 1425°C in melt-producing isothermal curves shown by the figure. Thus, the softening starting temp. of the core part is raised, and delayed reduction occurs hardly. Even if the iron content of the shell part is changed somewhat, the melting-down temp. is stably maintained at a high level, so the softening properties of the pellets at high temp. are improved.
INOUE KATSUHIKO