Granular metallic iron

Abstract

Metallic iron nuggets made by reducing-melt of a material containing a carbonaceous reductant and a metal-oxide-containing material, the metallic iron nuggets comprising at least 94% by mass, hereinafter denoted as "%", of Fe and 1.0 to 4.5% of C, and having a diameter of 1 to 30 mm are disclosed.

Description

[0001] The present invention relates to metallic iron nuggets made by reducing-melt of a material containing iron oxide, such as iron ore, and a carbonaceous reductant, such as coke, the metallic iron nuggets having a high Fe purity, specified C, S, Si, and Mn contents, and a specified diameter.[0002] A direct iron-making process for making reduced iron by direct reduction of an iron oxide source such as iron ore using a carbonaceous substance or a reducing gas has long been known. Extensive research has been conducted as to the specifics of the reducing process and continuous reduction equipment.[0003] For example, Japanese Unexamined Patent Application Publication No. 11-337264 discloses a rotary hearth that allows efficient continuous production of reduced iron, in which, during reduction by heating of green pellets prepared by solidifying a mixture of an iron oxide source such as steelmaking dust or fine ore and a carbonaceous substance using a binder, explosions which occur whe...

AI Technical Summary

Benefits of technology

[0013] The metallic iron nuggets are prepared by heating the material so as to react a metal oxide contained in the material with the carbonaceous reductant and a reducing gas produced by such a reaction and to reduce the metal oxide in the solid state, and further heating the resulting reduced iron in a reducing atmosphere so as to carburize and melt the resulting reduced iron and allow the reduced iron to cohere while excluding any by-product slag. During this process a CaO source is added to the material to adjust the basicity of the slag components in the material, i.e., CaO / SiO.sub.2, within the range of 0.6 to 1.8. In this manner, sulfur contained in the material can be efficiently captured by the slag produced during reducing-melt, and metallic iron nuggets having a S content of 0.08% or less can be obtained.

[0100] The resulting metallic iron nuggets of the present invention have a high Fe purity, a suitable carbon content, a uniform shape, and a size of 1 to 30 mm. Thus the metallic iron nuggets of the present invention exhibit high handling quality and can thus effectively used as an iron source for making iron, steel, or various alloy steels.

Problems solved by technology

In particular, in a method for making sponge metallic iron, the Fe purity is drastically low because the separation of the slag component that became mixed in the metallic iron is difficult.

Moreover, nearly all of the metallic iron obtained by a known direct iron-making process is sponge-shaped, and thus the handling thereof as an iron source is difficult since such metallic iron is fragile.

In order to actually use such metallic iron as a material for making iron, steel, or alloy steel, a process such as a secondary process to make briquettes therefrom is required, and the expenses for additional equipment therefor are considerable.

In the known processes, including these conventional techniques, for making metallic iron nuggets, no technology capable of efficiently making metallic iron having a diameter within a predetermined range while fully considering the quality and handling convenience of materials for making iron, steel, or iron alloy has been established.

Moreover, no specific manufacturing technology for controlling the carbon content within a predetermined range has been established.

This is also one of the main reasons for the degradation in quality of the metallic iron nuggets.

Accordingly, in order to make metallic iron nuggets of high value by a reducing-melt process, it is not sufficient to merely hope to increase the purity.

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