Kawasaki Steel Corporation

Kawasaki Refractories Co., Ltd.

Toshimitsu Koitabashi

Takao Hamada

Toshihiro Inatani

Mitsuo Sumito

Nobuo Tsuchiya

Yoshiyasu Takada

Yo Ito

Kyoji Okabe

Eiji Katayama

Takeshi Ogasawara

Takahisa Koshida

Hideshi Katayama

Kimiaki Sasaki

A powdery or fine granular ore containing metal oxides is melted and refined by charging the ore and a part of a reducing gas discharged from a vertical type of melting and reducing furnace into a fluidized bed type of preliminary reducing furnace to preliminary reduce the ore therein, charging the preliminary reduced ore heated at a high temperature into the above described melting and reducing furnace and melting and reducing the ore by using a carbonaceous solid reducing agent and air or oxygen rich air heated at a high temperature and discharging the molten metal and the molten slag from the melting and reducing furnace. By using the preliminary reduction step, the pretreatment of the powdery or fine granular ore containing metal oxides, such as formation into pellets, sintered ores, briquets and the like can be omitted.

Methods for melting and refining a powdery ore containing metal oxides

The powder of hexagonal boron nitride is prepared by heat-treating a powdery mixture composed of an oxygen-containing boron compound, e.g. boric acid, and a nitrogen compound, e.g. dicyandiamide and melamine, with admixture of minor amounts of a carbonaceous powder, e.g. carbon black, and/or borax. Further, an alkaline earth metal compound such as calcium carbonate is added either to the powdery mixture of the starting materials before the heat treatment or to the powder after the heat treatment. The h-BN powder has excellent sinterability so that sintered bodies of boron nitride having a high density and high bending strength can readily be prepared by use of a hot press.

Hexagonal boron nitride powder having excellent sinterability and a

A method of producing amorphous mother alloy is disclosed, which comprises charging raw material, carbonaceous reducing agent and secondary material into a smelting furnace and then smelting to produce Fe-B-Si series molten metal having a B-Si composition range which lies within an area represented by the trapezoidal area abcd shown in FIG. 2 of the accompanying drawings. The amorphous mother alloy is used to produce an amorphous starting material by diluting with molten steel.

Methods of producing and using amorphous mother alloy

Fe-B molten metal for producing amorphous alloys are produced in a low cost by using a vertical furnace wherein beds packed with a carbonaceous solid reducing agent are formed and two or three stages of tuyeres are provided in the lower portion of said furnace, feeding a preliminarily reduced powdery iron ore into the furnace through the upper stage of tuyeres together with hot air and feeding boron oxide or boric acid into the furnace through the lower stage of tuyeres together with hot air and, if necessary blowing hot air into the furnace through the lowest stage of tuyeres. In stead of the above described vertical furnace, a usual blast furnace provided with one or two stages of tuyeres at the lower portion of said furnace is used. In this case, sintered iron ore, pellet-formed iron ore or lump iron ore is fed from the top of the furnace and powdery boron oxide or boric acid is fed through the tuyeres.

Method for producing Fe-B molten metal

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Ichihara, Japan

Toshimitsu Koitabashi