JPS59133308A - Refinement for at least partially reduced iron ore - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for smelting at least partially reduced iron ore, especially sponge iron, in a molten gas generating furnace. In the molten gas generating furnace, the heat and reducing gas necessary to smelt the reduced raw material are generated from the coal input and the oxygen-containing gas blown into the furnace, but at this time the reducing gas is separated into solids. The solid material consisting essentially of dust-like carbon is at least partially circulated. A method of this kind can be known, for example, from DE-○s2843303. Such reduction methods have been developed with particular consideration to poor or non-coking carbon carriers. The drawbacks of these known methods are the following facts. The liquid metal produced in the molten gas has a relatively low carbon content and is metallurgically too cold. Furthermore, the sulfur content is relatively high due to the temperature profile in such molten gas generating furnaces and due to the input of lower quality coal. In order to improve this situation, methods have already been proposed to increase the temperature by supplying energy, for example by supplying an electric current to a plasma burner, or by blowing in preheated oxygen.

In the known process, a degassed, coked, fine or dusty coal is produced in a molten gas generator, which is conventionally returned to the post-separation stage in a high-temperature cyclone. These coal or coke dusts are recognized as being of high quality, containing about 90% carbon, and are equated with normal steel mill coke.

The aim of the invention is to increase the residence time of the hot sponge iron particles or pellets from the preceding reducing shaft in the thermally and metallurgically active zone of the molten gas generator, with the aim of further carburizing the liquid metal. It is accumulated. Above all, the carburization should ensure a reduction in the sulfur content and an increase in the silicon and manganese M contents.

In order to solve this problem, the present invention aims at turning at least a part of the solid separated from the reducing gas into agglomerates.
Its essence consists in ricketting and feeding the shaped coke thus obtained into a molten gas generating furnace in a pressure gas generating zone, in particular from above. The relatively high quality degassed, and in some cases;
Rather than being returned to the process in the hot zone of the furnace at the bottom of the molten gas generating furnace, with particle sizes much smaller than mm, it is agglomerated before being returned, especially when the gas is generated under pressure from above. The introduction into the zone ensures that the particles, which are now larger in shape and mechanically better able to withstand the loads, settle through the pressure gas generation zone and form a coke layer on the surface of the metal bath. Ru.

This coke layer serves in this case as a heat storage layer, so that the metal bath melting in the pressure gas generation area has to sink through this coke layer, so that an exchange takes place in the liquid phase with the formed coke. , thereby carburizing the bath. Such an effect is not directly achieved by dusty coal particles such as those separated from the reducing gas. This is because the maximum size of these grains is about 1 m78, which prevents settling and such buffering/
'! This is because the mechanical stability is too poor for a Y configuration.

Rather, in the known process, the returned dusty coal is largely gasified and serves to maintain a fluidized bed of coal in the pressure gas generation area of the molten gas generator.

Molded coke, which is introduced from above into the molten gas generation furnace, absorbs most of the sensible heat as it passes through the pressure gas generation area, but that heat is of course also generated by partial combustion of the coal with oxygen, resulting in carbon monoxide and hydrogen. Because of the temperature that can be reached by heating, it is always less compared to the sensible heat that coke absorbs in a blast furnace, for example. The layer of shaped coke formed below the pressure gas generation zone, however, now undergoes a vigorous exchange with the molten metal descending, so that metallurgical carburization is achieved.

According to the invention, the shaped coke added in agglomerates should preferably be in agglomerates with a size of at least 12 wings and especially at most 5 Qmm. , thereby ensuring that, despite the high mechanical loads imposed during passage through the pressure gas generation area, the particles always reach the lower area of the molten gas generation furnace sufficiently agglomerated to form the desired slow-swelling layer. Guaranteed. In accordance with the present invention, shaped coke is introduced into the molten gas generator in an amount sufficient to form a layer of shaped coke between the melted and fluidized metal scrap and the pressure gas generation area of the molten gas generator. In this case, priority is given to

For example, in order to make solid particles separated by a hot cyclone into particles of the required size, a cold binder is added to the hot separated solid material before briquetting.
That's convenient. The briquetting process is usually carried out at temperatures below those at which dusty coal is produced. The heat content of the dusty coal can thereby be fully utilized for preheating the binder. This eliminates the need for additional binder and heating. It is often convenient to add a binder to the hot separated solid material in a heat exchanger, with the recovered heat used to preheat or harden the formed coke before returning it to the melter. It can be used for

In a simple manner, hard pitch, bitumen and/or bituminous lignite can be used as binder.

In order to improve the mechanical stability of the shaped coke, iron oxide powder, especially from blast furnace gas fabrication plants, can be added to the solid material to be agglomerated together with a binder. In this way, at the same time, the solid substances contained in the process waste gas are further recovered. Particularly advantageously, this method
After solids separation, the reducing gas is subjected to a gas scrubbing, which is carried out by adding the repellent carbon-rich mud of the gas scrubbing together with a binder to the agglomerated solid material. Overall, there is one operating principle here, which is that high-volatile coal can still be used for pressure gas generation. Just such coal has a tendency to crackle and sizzle on the production of pressurized gases, thereby resulting in a degassed material of relatively high quality, mostly in the form of dust for forming coke production. Shaped coke produced by aIS by agglomeration or briquetting can be returned to the process at high temperatures, thereby not placing a heavy burden on the energy balance and reducing the risk of explosions as has recently been the case. During briquetting, metal additives such as aluminium, silicon or magnesium can be briquetted together in a simple manner, so that the formed coke is in a particularly preferred form with a grain size of 12 to 60 mm and then transferred to the molten gas generator. It can be introduced into.

The invention will now be described in detail with reference to schematic diagrams outlining the following steps.

In the figure, 1 is the ore on the reduction shaft 2! Represents a belt wrap for loading. Via the distributor 3 the reducing gas is introduced into the reducing shaft, the reducing gas line for this being indicated at 4. The ore descending down the reduction shaft is introduced into the molten gas generating furnace 7 via the sponge iron discharge screw conveyor 5 and the sponge iron downtake 6 at a temperature of about 900'C, and at this time the cooling gas parallel pipe 8 is introduced into the sponge iron downtake 6. Equipped for iron downtake.

In the molten gas generator γ, a coal fluidized bed 9 is maintained in the upper area, in which the coal introduced is gasified,
Generates the energy necessary for smelting metals. At this time, coal is supplied at a location indicated by 10. At 11, the outlet of the gas generating furnace is shown. Cooling gas is fed into the gas of the gas generator at 12 points. A cooling gas supply port to the head of the gas generating reactor is indicated by 13.

The gas from the gas generating furnace discharged via the conduit 14 is removed in a high-temperature cyclone 15 of any solid substances it may contain, especially coal in the form of dust, and the pulverized coal is sent to the molten gas generating furnace 7 via the conduit 16. It is returned in the lower pressure gas generation area. This divided flow of dusty coal returning to the source is the heat exchanger 1.
7 into which the binder is fed from a reservoir 18. After the necessary temperature adjustment, the mixture of coal and binder reaches the briquette soles 19 and passes through a storage tank or distributor, where it can be heated by the heat from its jacket heat exchanger 17. Grain size 12 to 5QvI71
The agglomerated material is then fed into the bath molten gas generating furnace 7 from above through the coal supply port 10 via the conduit 21,
The force of gravity passes through the pressure gas generation area to the lower area of the molten gas generation furnace, where a formed coke layer η is formed above the fluid bath 23. This molded coke layer 2
2 must extend to the level of oxygen blowing or slightly below this level, where the oxygen nozzle is shown at 24.

The proportion of carbon separated and recycled by the hot cyclone 15 typically corresponds to approximately one-fourth to one-sixth of the amount of coal input.

Claims (8)

[Claims] (1) When smelting at least partially reduced iron ore, especially sponge iron, in a molten gas generating furnace, the heat and reducing gas necessary to smelt the reduced raw material are added to the coal. Generated from gas containing oxygen blown into it,
At this time, in a smelting method in which the reducing gas is subjected to solid separation and at least a part of the solid material consisting of substantially dusty carbon is circulated, at least a part of the solid material separated from the reducing gas is made into a lump. , in particular at least partially reduced iron ore, in particular sponge, characterized in that it is briquetteted and the shaped coke thus obtained is fed into a molten gas generator in the area of pressure gas generation, in particular from above. How to smelt iron. (2) 12 or more solid substances separated from the reducing gas;
2. A method according to claim 1, characterized in that the method is characterized in that it is agglomerated to a particle size of less than 50 centimeters. (3) Charge formed coke into the molten gas generating furnace in an amount sufficient to form a layer of formed coke between the molten metal and the pressure gas generating area of the molten gas generating furnace. A method according to claim 1 or 2, characterized in that: (4) A method according to claims 1 to 6, characterized in that the hot separated solid material is mixed with a cold binder. (5) The hot separated solid material is mixed with a binder in a heat exchanger, the heat recovered being used for preheating or hardening of the shaped coke before it is returned to the molten gas generator. A method according to claims 1 to 4. (6) The method according to claims 1 to 5, characterized in that hard pitch, bitumen and/or bituminous lignite are used as the binder. 7. Process according to claims 1 to 6, characterized in that iron oxide powder, in particular from a blast furnace gas purification plant, is added together with a binder to the solid material to be agglomerated. (8) subjecting the reducing gas to gas cleaning after solid separation;
8. Process according to claims 1 to 7, characterized in that the carbon-rich mud produced during the gas scrubbing is added together with a binder to the solid material to be agglomerated.