EP0036382A1 - Process and apparatus for producing liquid iron - Google Patents

Abstract

To produce liquid iron directly from oxidic iron compounds, an iron bath is saturated with carbon by blowing in a carbon carrier using a neutral or reducing carrier gas. According to the invention, a pouring cone of iron ore is formed on the surface of the bath in the central zone and oxygen is blown onto the free surface of the bath in the peripheral zone, the bath being flushed with a neutral gas through at least one blow stone arranged in the bottom of the vessel. A metallurgical vessel (1) contains an iron bath (40) and has a closure cover (20) into which a chimney (30) opens, at least one oxygen inflation lance (21) aiming at the edge zone (3) through the vessel cover (20) and a blowing lance (12) for the solid carbon carrier projects under the bath level, while at least one blow stone (11) is located in the vessel bottom (10) below the center of the bath level.

Description

The present invention relates to a method and a device for producing liquid iron, in particular for producing directly from oxidic iron compounds.

There has been no shortage of attempts in the past to produce liquid iron from ores as far as possible using the direct process.

For example, a process has been described according to which the raw materials are first converted into sponge iron using a suitable gas and then melted in a metallurgical vessel, in the melting vessel by reaction of oxygen-containing gases with carbon-containing substances, which are primarily blown in under the bath surface , Heat energy, and carbon monoxide are formed. The heat is partly used to melt the sponge iron and the exhaust gas is used for the direct reduction of ores. However, the entire exhaust gas is initially treated in a separate reactor with coal dust and with water vapor.

According to a further known method, which is used to produce liquid steel from ore without a separate pig iron phase, a reducing gas is produced in a combined melting and gas generating reactor provided with an additional heater by reacting a fuel with oxygen, which gas is produced in a subsequent reduction chamber in countercurrent of an ore feed, while the pre-reduced ore obtained at the end of the reduction stage is conveyed into the heated melting and gas production room, where it is melted and then freshly refined.

In a further process which is aimed at the direct production of pig iron, two separate feed or reaction zones are provided in the smelting and gas generating reactor. In a first zone, a carbon carrier is introduced directly into the bath in order to maintain a carbon content of the metal melt, which is preferably above 2%. In a second adjacent zone, part of the carbon bound to the melt is released of heat and reducing gases burned using oxygen. The carbon supplied by a lance is thus used here on the way through an intermediate carburizing of the iron bath essentially to increase the melting capacity of the bath and to form reducing gases.

When using the methods mentioned, it is therefore primarily dependent on the production of a gas which has a composition which is necessary for reducing or at least pre-reducing ores.

In order to produce strongly reducing gases in the context of a combined reduction melting process, however, expensive and complicated measurement and control measures and measures have to be taken to make the process run in the desired manner, if one does not prefer to separate the resulting gases to treat them in order to provide them with sufficient reduction potential.

The aim of the invention is therefore to propose a method which allows the direct production of molten pig iron in a single vessel, the aforementioned difficulties being avoided, and a suitable device for this.

This goal is achieved by the method according to the invention, which provides for saturating an iron bath with carbon by blowing in a carbon carrier by means of a neutral or reducing carrier gas and which is characterized in that a pouring cone of iron ore is formed on the bath surface in the central zone and onto the free bath surface of the peripheral zone blows oxygen, the bath being flushed with a neutral gas through at least one blow stone arranged in the bottom of the vessel.

The idea on which the invention is based is that the composition of the gases formed when oxygen is blown onto an iron bath saturated with carbon by simultaneously flushing with neutral gas according to the invention can be controlled.

If it is intended to use the exhaust gases for the pre-reduction of ore, a practically 100% CO exhaust gas with a high reduction potential can be produced by specifically supplying oxygen with reduced flushing.

In this case, you will prefer a hard oxygen blowing method and flushing the bath with inert gas to 0-0.1 Nm3 / t.hour. restrict.

On the other hand, by thoroughly flushing the bath with inert gas, the resulting carbon monoxide can be post-burned on the surface of the bath, which takes place with intense heat generation. The amounts of purge gas are then preferably between 0.1-0.3 Nm3 / t.hour. The additional heat generated on the surface of the bath can be used to melt the iron ore just applied there.

Furthermore, the iron bath is generally mixed by the inert gas stream with the carbon carrier, preferably coal dust, suspended therein, and in the event of saturation of the bath, solid carbon that is not bound to iron is carried to the bath surface, where it is available for reducing the molten ore.

The heat supply to the bath itself is accomplished by continuously or intermittently blowing oxygen onto the surface of the outer zone. Inflation onto the bath surface is not hindered by the presence of molten and freshly applied iron ore, since the latter is primarily on the surface of the central zone.

Through a sensible arrangement of the oxygen inflation lance, the introduction nozzle for the carbon carrier and the blowing stones to each other, it is achieved that flow conditions are formed within the bath which are generally oriented downwards from the side walls of the vessel and upwards from the center of the vessel bottom. Hereby causes that in the central zone, where the bath surface is exposed to ore, both the main part of the CO post-combustion takes place, which supplies the energy necessary for melting the ore, and also carbon, which can be used to reduce the ore. In the peripheral zone, the bath is saturated with oxygen and heated.

Of course, there is the possibility of estimating the fill level of the vessel using the balance of the raw materials and the withdrawn liquid products, but other known methods for level measurement can be used here without any problems.

The device required to carry out the method according to the invention consists of a metallurgical vessel (1) in which there is an iron bath (40) and which understands a closing cover (20) into which a chimney (30) opens, at least one oxygen inflation lance (21 ) through the vessel lid (29) aims at the edge zone (3). and a blowing lance (12) for the solid carbon carrier projects under the bath level, while there is at least one blow stone (11) in the vessel bottom (10) below the center of the bath gel.

The nozzle of this blowing lance is conveniently located near the blowing stone and between the same and the lower edge of the partition. With the appropriate setting of the individual gas pressures (inflation lance, blowing lance, blow stones), this can cause currents to form inside the vessel which rise towards the inner zone and decrease along the vessel migration.

Thanks to the heat generated directly at the bathroom mirror by CO afterburning, Fei.nerz or lumpy ore can be charged, whereby the energy-consuming, expensive grinding costs are eliminated.

In the course of the process according to the invention, liquid iron with a carbon content above 2% is formed, which is expediently fed to a continuously operating fresh plant.

Further advantages and features will become apparent from the description of the drawing, in which FIG. 1 shows a section through the device according to the invention.

One recognizes the metallurgical vessel (1) which understands a closing lid (20) in the middle of which the chimney (30) is arranged. Through this ore (Fe203) is filled into the vessel (1).

The oxygen inflation lances (21, 22) are arranged above the edge zone (3).

Under the central zone (2), the blow stones (11) are arranged in the vessel bottom (1), through which the bath (40) is flushed with a neutral gas, which thus generates an ascending flow towards the inner zone.

You can also see the blowing lance (12) with its nozzle (16) for blowing the solid carbon carrier into the bath.

The vessel also has the tap openings (13 and 14) for the liquid metal or the slags.

Claims (5)

1. Procedure for the production of liquid iron, in particular for the direct production from oxidic iron compounds, which provides for an iron bath to be saturated with carbon by blowing in a carbon carrier by means of a neutral or reducing carrier gas, characterized in that egg on the bath surface in the central zone. ne forms a pouring cone of iron ore and blows oxygen onto the free bath surface of the peripheral zone, the bath being flushed through with a neutral gas through at least one blow stone arranged in the bottom of the vessel 2. The method according to claim 1, characterized gekennzei: chnet that to achieve an exhaust gas consisting practically only of CO, the bath is specifically charged with oxygen and the amount of purge gas to 0-0.1 Nm3 / t iron. Hours limited. 3. The method according to claim 1, characterized in that 'the energy required to melt the ore introduced into the inner zone is applied by continuously and intensively (0.1-0.3 Nm3 / t iron. Hrs. ) flushed with a gas, preferably inert gas, from the bottom of the vessel and thereby causes an afterburning of the carbon monoxide formed during the oxygen blowing on the surface of the bath. 4. The method according to claims 1-3, characterized in that the heat is supplied to the bath by continuous or intermittent inflation of oxygen on the bath surface in the peripheral zone. 5. Device for carrying out the method according to claims 1-4, characterized in that a metallurgical vessel (1) contains an iron bath (40) and understands a closing lid (20) in which a chimney (30) opens, at least one Oxygen inflation lance (21) through the vessel cover (20) aims at the edge zone (3) and ei.ne blowing lance (12) for the solid carbon carrier, protrudes under the bath level, while at least in the vessel bottom (10) below the bath level a blowing stone (11) is located.

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