Studies on the Nickel Matte : I. Nickel-Iron-Sulphur System

Abstract

Main raw material for metallic nickel in Japan is garniellite, and the matte-smelting process is usually adopted here. The nickel matte produced in this process is, therefore, a ternary mixture of nickel, iron and sulphur, and it is usually ferromagnetic. The relationship of the magnetic properties of the nickel matte to its composition is considered to be important both from fundamental and practical points of view. The authors conducted measurements of the intensity of magnetization, thermomagnetic analyses and X-ray studies on prepared specimens of the binary system Ni-S and of the ternary system Ni-Fe-S. In the system Ni-S and Ni-Fe-S, ferromagnetism was found in a limited region, and it is due to the metallic nickel phase in Ni-S and the nickel-iron alloy phase in Ni-Fe-S. The hexagonal phase NiS and the cubic ternary compound (Ni, Fe)₉S₈ were investigated with X-ray, and their lattice parameters were determined. Furthermore, the range in which (Ni, Fe)₉S₈ exists was also fixed. They are as follows : a=3.436 kX, c=5.351 kX and c/a=1.557 in NiS, and the range of the existence of (Ni, Fe)₉S₈ ; 22.2 atom.% Ni and 30.7 atom.% Ni in the section of 47.1 atom.% S, and a=10.129 kX in (Ni, Fe)₉S₈ saturated with FeS a=10.095 kX in (Ni, Fe)₉S₈ saturated with Ni₃S₂. The continuous solid solution of NiS and FeS₁₊ₓ, the hexagonal phase η, was also investigated with X-ray. The Curie temperature of the specimens in the ternary system showed rather peculiar behaviors in relation to their compositions. This peculiarity of the Curie temperature seems to be due to the deviation in the content of nickel in the alloy phase of matte. Other two magnetic transformations were also observed ; one was found with the specimens in the region γ+δ+π (see Figs. 1 and 9) at about 480°C in heating and at about 420°C in cooling. The authors considered this transformation to be related to the order-disorder transformation in the Ni₃Fe lattice. The other was found in the region γ+ε and in the iron side of the region γ+ε+π. This transformation was found to be due to the α⇄γ transformation in the nickel-iron alloy phase. The properties of the nickel matte taken from the converter of a nickel smelter were also examined, and the results were in good agreement with those of the prepared specimens.