珪ニッケル鉱石の還元機構について-フェロニッケル製錬に関する基礎的研究(第2報)- Reduction Mechanism of Siliceous Nickel Ores-Fundamental study on Fe-Ni smelting(2nd Report)-

Siliceous nickel ore, raw material of Fe-Ni smelting, is composed of minerals such as garnierite, serpentine, goethite and admixture like quartz, olivine and so on. Ni concentrates in garnierite and serpentine, while Fe does in goethite. Reduction behavior of garnierite, goethite and mixture of both minerals was investigated by X-ray diffraction method to clarify how these minerals react each other to form Fe-Ni alloys as well as slag in the process. The following results were obtained. (1) Nickel recovery from the silicates is very difficult due to less reducibility and poor agglomeration of the metal. (2) When goethite exists with silicates in a reducing atmosphere, FeO in goethite replaces NiO in silicates to form (Fe, Mg)2SiO4 during re-crystallization of the silicates. (3) Molten phase of (Fe, Mg)2SiO4 with low melting point appears in the materials above 1,473 K. It assists the direct reduction of free NiO along with FeO and simultaneously the agglomeration of reduced metals.