Method of and apparatus for manufacturing the metallic iron

Abstract

A method of manufacturing reduced iron at high Fe purity efficiently with less intrusion of a slag components using less carbonaceous reducing agent and fuel, comprising charging a compact of the iron oxide containing a carbonaceous reducing agent in a packed bed, reducing the iron oxide to 90% or more while keeping in a solid state by a heat source formed from the lower portion of the furnace and then melting the same, as well as an apparatus for manufacturing the metallic iron, comprising a fire grate disposed in the inside of a packed bed, a compact charged layer on the fire grate, a charging product charging mechanism for supplying the compact and a mechanism for discharging an exhaust gas in the furnace, and a fuel charging mechanism, a fuel combustion space and a molten product stores bath disposed below the fire grate.

Description

[0001] 1. Field of the Invention[0002] This invention concerns a technique of heating iron oxide containing materials such as iron ores together with carbonaceous reducing agents such as carbon materials and reducing and melting them to obtain metallic iron and, more specifically, it relates to a method of and an apparatus for manufacturing the metallic iron at high purity by separating a slag components intruded as a gangue mineral in iron oxide sources by using a packed bed.[0003] 2. Statement of Related Art[0004] As a direct reduction method of directly reducing the iron oxides such as iron ores or iron oxide pellets by a carbon source such as a carbon material or a reducing gas, a packed bed method represented by a Midrex process has been known so far. The direct reduction method of this type is a method of blowing a reducing gas reformed, for example, from natural gases through bustle ports charging mechanism at a lower portion of a packed bed and reducing iron oxides by utiliz...

AI Technical Summary

Benefits of technology

[0014] Further, according to the method of this invention, the compact may be reduced and melted by charging the compact above the fire grate disposed in the inside of a furnace used as the packed bed, and burning the fuel below the fire grate or providing a layerd bed comprising refractory material or a lumpy carbonaceous material having open cells when layered bed may be disposed on the fire grate. Further, it is desirable to supply an oxygen-containing gas from a gas supply port above the fire grate to burn the gases generated from the compact in order to increase the heat efficiency by the effect of utilizing the reducing gas. It is also preferred to mix an auxiliary fuel to the oxygen-containing gas. Further, it is also effective to supply an auxiliary fuel toward the space below the fire grate in order to enhance the effect according to this invention.

[0019] The present inventors have made earnest studies for dissolving the foregoing subject and have found that reduced iron at high Fe purity with less inclusion of the slag components can be produced by using less amount of the carbonaceous reducing agent and less fuel consumption, and loss of refractories can be suppressed, by charging a compact at least comprising a carbonaceous reducing agent and an iron oxide containing material (hereinafter sometimes referred to simply as "compact") in a packed bed, burning the fuel sufficiently below the fire grate, heating and reducing of the iron oxide contained in the compact to more than 90% while keeping the compact in a solid state, and then melting the same.

Problems solved by technology

However, since the reduced iron obtained by the conventional reduced iron production method includes a great amount of slag componentscomponents such as SiO.sub.2, Al.sub.2O.sub.3 and CaO contained in the iron oxide used as the raw material (gangue elements in iron ores) or carbon material (ash in coals), there are a problem that the purity of the metallic iron (iron quality) is lowered.

While the slag components can be separated and removed by the following refining step, the increase in the amount of slags not only lowers the yield of the refined molten iron but also gives undesired effects on the operation cost of the electric arc furnace, so that reduced iron of high quality and with less content of the slag has been demanded.

However, iron ores of high iron quality have to be used as the raw material for the manufacture of reduced iron in the existent reduced iron manufacturing method, which greatly narrows the range for the selection of practical iron making materials.

Further, it is a final purpose to obtain reduced solid products as intermediate products in the existent method as described above and this requires additional steps of transportation, storage, briquetting or cooling till they are sent to the following step of refining, to result in problems that large energy loss is caused or the energy and the special apparatus are required for briquetting.

However, since this method requires two steps of preliminary reduction and final reduction in the molten iron bath, it involves a problem not only of troublesome operations but also of remarkable loss of refractories since the molten iron oxides (FeO) present in the molten bath are in direct contact with refractories.

However, although the metallic iron at high purity can be obtained in this method, it requires a large scale facility and it is difficult to save spacing for the facility.

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