PURPOSE: To produce a raw molten Ni stainless steel at a lower cost than the conventional method by combining ore contg. simultaneously oxide of Fe, Ni, Cr such as laterite and direct use of the combustion heat of an inexpensive carbonaceous material as reduction reaction heat.
CONSTITUTION: Oxide ore such as laterite contg. Fe, Cr and Ni in combination and ore contg. MgO and SiO2 together with oxide of Cr and Fe are mixed together with a carbonaceous material such as coke and the mixture is molded. The weight ratio of Fe:Cr:Ni in said raw material is adjusted to the value required by the compsn. of the raw molten Ni-contg. stainless steel to be produced, for example, 74:18:8. The above-described molding is then heated to 1,000W 1,400°C and is preliminarily reduced then the molding is charged together with a carbonaceous material such as coke and a flux into a top and bottom blown converter type melt-reduction furnace. Top and bottom blowing of oxygen is performed in this state to burn partially the carbonaceous material and the melt reduction is progressed while controlling the temp. so as to attain the solidifying temp. of the metal or above and ≤1,580°C under strong stirring. The intended raw molten Ni-contg. steel is thus obtd.
KUWABARA MASATOSHI
ISHIKAWA HIDEKI
SAITOU TSUTOMU
INOUE NORIYUKI
FUJITA MASAKI
JAPAN METALS & CHEM CO LTD
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