DE872952C - Method of making sponge iron - Google Patents

Description

Method of making sponge iron The invention relates to to a method for reducing iron from iron ore by means of carbon oxide and optionally Gases containing hydrogen at temperatures below the melting point of Iron and iron ore.

Almost the entire amount of malleable iron is used today indirect routes, d. H. won by way of the blast furnace. In the blast furnace a pig iron is primarily produced, which contains considerable amounts of other components contains. This primary pig iron must be converted into malleable iron Subject to cleaning, the so-called freshness. Except for indirect generation Attempts have also been made to make malleable iron on the way over the blast furnace Producing iron directly from ore. A major advantage of this direct iron production is the special quality of the at temperatures below its melting point obtained iron, which is therefore an excellent starting material for production of stainless steel forms.

To this day, however, efforts are made towards the direct generation of malleable iron has not been economically successful.

An object of the present invention is to provide such improvements in the Procedure and establishment for the direct production of forgeable To develop iron from iron ore which this type of iron production using ahead of cheap and almost ubiquitous mineral or other solid fuels enable while achieving a high level of economic efficiency.

At the same time takes place thereby the generation of a valuable, in particular suitable for the synthesis of hydrocarbons from carbon monoxide and hydrogen Furnace gas instead.

The method according to the invention also allows the reduction of the Iron ore for the direct production of malleable iron with a reducing, namely carbon-oxide-containing gas without any other supply of heat to the reducing ore than the sensible heat of the reducing gas.

It is known that iron can be obtained by reducing iron ore by that the ore to be processed is in a vertical shaft through which the ore slowly moving from top to bottom, treated with carbon dioxide-rich gases, that circulate through the shaft and a space connected to it, in which is the cycle gas enriched with carbonic acid by the reduction of the ore with a solid fuel at an elevated temperature to convert the carbonic acid is brought into contact in carbon dioxide. Simultaneously with this, the circulating gas becomes heated to a high temperature, preferably around rooo °, which, however, is still below the melting temperature of the iron and the gait is so that the gas at its Paths from bottom to top through the reduction shaft for the reduction and the Preparation of the ore can give off required heat to the shaft filling: It It has also been proposed to make malleable iron by reducing iron ore at temperatures below the melting point of iron using air with increased oxygen content and coal. Some practical realization however, has not yet found this stimulus while applying air with an increased oxygen content in the usual blast furnace already with a certain amount Success has been carried out. The reason why i would use air with increased oxygen content in the direct production of malleable iron no essential. Has given advantage is probably to be found in the fact that: the Working temperature here in contrast to the blast furnace is much lower, so that the temperature, which in common gas generators. for the preparation of carbonaceous Gases is observed, sufficient to urnd a reducing gas of such temperature. produce such a heat content that thereby or heat requirement of the reduction shaft can be covered.

According to another, but not previously published, proposal from a shaft generator with liquid slag discharge for the reduction of the Iron ore suitably composed to sponge iron and sufficiently hot, reducing Gas withdrawn and fed to the reducing device. Such a shaft generator however places very strict conditions on the lump fuel to be gasified, so that such a generator is comparatively expensive to operate.

The invention, on the other hand, is that to reduce iron ore by means of carbon dioxide and optionally hydrogen-containing gases at temperatures below the melting point of iron and iron ore from a powdered fuel by gasifying with oxygen a reducing gas with a total content of carbon oxide and hydrogen of more than 70% is produced, the temperature of which is that of the reduction of the ore to be used, and that with the one to be treated Ore is brought into direct contact.

According to the invention, it is appropriate to the content of the reducing To increase the gas in carbon dioxide and hydrogen to more than 85%. The reducing The gas advantageously has a temperature of around zooo °.

In the context of the following description, oxygen means and the claims understood an oxygen-containing gas, its oxygen content is more than 85 0 / u.

The use of dusty fuels is for the specified The purpose is particularly advantageous because it is then less valuable and therefore cheap Fuels can be used that would otherwise have no use.

About the production of malleable iron by reducing iron ore at temperatures below rooo ° using any dusty fuel To enable the method to be carried out, a gas generation method is preferably used applied, which consists in that one from a finely divided solid fuel and oxygen in such a proportion that the carbon of the fuel is converted into carbon oxide at most, produces a mixture that is as homogeneous as possible, and that now this mixture in the form of a jet in one at high temperature located reaction space is initiated, in which it is with the formation of im essentially carbon dioxide ignited with a slight admixture of carbonic acid.

This gasification process occurs in the reaction or gasification chamber very high temperatures. To protect the walls of the reaction chamber from damage To protect from the high reaction temperature, it was provided in the reaction chamber a medium which reacts endothermically with hot carbon, e.g. B. water vapor or Carbonic acid to be introduced in such a way that between the zone of highest temperature and the Walls of the reaction chamber a continuous, coherent stream of the introduced endothermic medium flows which envelops the zone of exothermic reaction.

It may be beneficial in place one endothermic reacting: medium as protective gas in the reaction chamber carbon oxide gas, possibly also a mixture of carbon monoxide and endothermic reacting media (Water vapor and / or carbon dioxide). The amount of endothermic reacting Media that is admitted in this case in the protective gas depends essentially on the Reactivity of the solid powder fuel to be gasified. is The responsiveness of the fuel is great, so you can get a relatively large amount Add water vapor because the endothermic reacting medium quickly with the Reacts fuel to form carbon oxide and hydrogen. Instead of steam you can also use a mixture of steam and carbonic acid or carbonic acid take alone. On the other hand, it is the reactivity of the solid, powdery fuel low, it must be entirely due to the addition of endothermically reacting media to the inert gas can be dispensed with.

In such a gas generator, the inventor previously produced a gas which had a carbon oxide and hydrogen content of up to 95010 ° at a temperature of 100,000.

With a reducing gas produced in the manner described, the iron ore can be reduced in a short time and in comparatively small treatment rooms to such an extent that a product is obtained which contains about 850% of the iron in elemental form. Such a product can then easily be converted into steel in conventional electric furnaces with reduction of the remainder of the iron oxides.

Another advance in the reduction of iron ore at temperatures of about 100 ° is achieved by: the production of carbon monoxide and hydrogen containing reducing gas and the reduction of iron ore at elevated pressure is made. An overpressure of 10 to 15 atm is advantageous. applied.

The increase in pressure makes it possible to both the gasification as also the reduction of iron ore in a comparatively small area with high intensity perform. In particular, the reduction of iron ore is proceeding very rapidly in front of you when the pressure is increased. It is then also possible to adjust the flow velocity . of the reducing gas within the treatment room filled with iron ore is essential to belittle. One is thereby able to also fine-grained iron ores and such Treat iron ores, which tend to disintegrate when reduced.

The higher resistance that the reducing gas in the fine-grained iron ore is easily overcome by the gases under increased pressure. by the way one can determine the permeability of the filling of the reduction space for the reducing gas by adding a piece of iron to the ore that does not take part in the reaction Good, for example lump coke, mixed in, which after the reduction of the ore by sieving or separated in some other suitable manner and then recirculated to loosen up of iron ore is used.

If you apply a carbonaceous material, e.g. B. coke or smoldering coke, of sufficient reactivity to loosen the iron ore in the reaction space on, methane may also be formed from carbon oxide and hydrogen according to the equation 2 C O -I-: 2 Hz = C H4 -; - C 02 a. You then get a powerful one Exhaust gas, which in an advantageous manner, for. B. to melt down the sponge iron produced Can be used in hearth ovens or the like.

The gas emerging from the reduction stage in the process according to the invention contains not only carbonic acid but also considerable amounts of carbon dioxide and hydrogen. If, for example, a gas is used that contains 82.5% C 0 and 13% H2 in addition to 2% C02, then after the reduction of the iron ore, an exhaust gas with a content of 3q.0 / 0 CO, 7.51 / o H2 and 50.5 "/ o CO2-The rest is water vapor and a small amount of nitrogen (about -. 0/0), depending on the purity of the oxygen used.

After removing the carbonic acid, such a gas can pass through a scrubbing of the gas with water under increased pressure, with advantage for the generation used by hydrocarbons or other valuable bodies.

Some of the carbon dioxide removed from the gas can be used under certain circumstances return in the circuit to the gasification stage of the process.

The method according to the invention is based on an embodiment that is shown in the drawing, explained in more detail.

In the device shown for carrying out the invention The gasification process is a vertical one that widens slightly from top to bottom Shaft i, which is bounded by fireproof masonry 2: which is in a gas-tight Sheath 3 made of sheet steel or the like. Is arranged. In the refractory lining 2 cooling pipes 4 are provided, which cooling water from an elevated tank 5 through the Pipeline 6 flows in, and from which the water flows through the pipeline 7 to the container 5 goes back.

At the upper narrower end of the shaft i flows coaxially to this a water-cooled nozzle 8 through which a homogeneous mixture of finely divided powdered fuel and oxygen in the form of a jet in the gasification shaft is initiated.

The finely divided fuel to be gasified comes from the storage container 9 by means of a screw conveyor io into a mixing device i i, which is driven by the Pipe 12 is supplied with oxygen under increased pressure. The formation of the homogeneous Mixture between oxygen and pulverulent fuel takes place in the facility i i at a comparatively low temperature, so that the mixture is only within the Gasification shaft i at the exit from the nozzle 8 ignited.

The storage bunkers 9 are designed so that the in the mixing device Incoming oxygen cannot get into the container 9.

The mixture entering through the nozzle 8, which is oxygen and fuel in such a proportion that when reacting in your at high temperature working gasification shaft, preferably carbon oxide, settles in the gasification shaft at a very high temperature in an exothermic reaction. The reaction goes on suitable fineness of solid fuel and good mixing at very high speed in front of him, so that almost the entire combustible part of the fuel is gasified. The fuel is preferably used in such a fineness that it is sieved on a sieve with q: 900 meshes per square centimeter only about 100 / a as residue to lie down.

Around the walls 2 of the gasification shaft in the area of the exothermic zone Reaction to protect against the very high temperatures prevailing there, turns a relatively cold protective gas is supplied from the pipes 13 into the nozzle 8 surrounding annulus 1q. flows, which is through an annular nozzle 15, the is arranged coaxially to the nozzle orifice 8, opens into the gasification shaft i. The ring nozzle 15 is designed so that the flow of cold protective gas in the Zone of exothermic reaction in the middle of the shaft and along the walls of the gasification shaft flows in a coherent continuous stream. A cold or moderately preheated carbon oxide-rich gas is advantageously used as the protective gas Gas on. But you can also use a certain amount of water vapor and / or the protective gas Add carbonic acid, depending on the nature and reactivity of the food to be processed solid fuel.

In the lower part of the gasification shaft i openings 16 are also provided, in order to be able to introduce further amounts of a cold gas rich in carbon oxide, which serves to set the temperature of the gases withdrawn from the gasification shaft i quickly to about iooo '° ``. The sudden lowering of the temperature - will supported by the fact that the gasification shaft merges into a cooling jacket 17, which is in communication with the cooling water tank 5.

The solid residue resulting from the gasification of the fuel settles on the bottom of the cooling container 17 at 18 and can then be drawn off into the ash container 2o by the discharge device 19.

The generated carbon-oxide-rich gas, which also contains hydrogen, pulls through the pipe 2i and gets directly into the with the to be processed Iron ore filled reduction shaft 22.

The reduction shaft z2, like the gasification shaft i, is also included surrounded by a gas-tight jacket. The ore to be processed comes from bunker 23 and is entered into the gasification shaft 22 via a lock 24 at the upper end. Ore and reducing gas therefore go through the shaft 22 in countercurrent to one another.

In the embodiment shown, all of the hot reducing gas is introduced into the reduction shaft 22 at the lower end. Under certain circumstances it can also be advantageous to direct some of the hot reducing gas to higher zones initiate the reduction shaft. The reduction shaft is preferably so operated that a temperature of as large as possible of its height about iooo '°' is held. The treated with the reducing gas can be from the Shaft 22 through the discharge device 25 into the container 26 for further use subtracted from. Under favorable circumstances it contains about 851 / o elemental iron, so that it can readily be converted into an electric with reduction of the remaining iron ore Furnace or a hearth furnace can be converted into liquid steel. In certain circumstances one can also treat the iron with magnets or in some other suitable way Focus wisely.

The furnace gas is withdrawn through the pipeline 27, which leads to a dust separator 28, in which the ore dust that is entrained is deposited. The deposited dust can be drawn off into the container 29. The gas freed from dust goes through the pipe 30 into a scrubber 31, which works under substantially the same pressure as the gasification shaft 2, 2 and the dust separator 28. In the scrubber 31, the gas is brought into contact with water, which is about is injected through nozzle 32 and drains down at 33. The washer 31 acts essentially like a cooler. In addition, considerable amounts of impurities are also excreted.

The scrubbed gas is then completely removed in a dedusting unit entrained dust and other impurities are freed and then enters a further scrubber 36, from which it is withdrawn at 37 for further use.

If the washer 36 is operated under increased pressure, then there is an absorption of carbonic acid takes place, so that the gas withdrawing at 37 is practically only from carbon oxide and hydrogen with small admixtures of carbonic acid and Nitrogen.

From the line 37, through the pipeline 38, the pump 39 and the pipeline @iqo draw off part of the generated gas and the manhole openings 16 in the carburetor shaft i.

Cold gas from the pipe 1q: 0 can also be passed through the branch line 141 into the lower part 142 of the reduction shaft, which is designed as a cooling jacket 22 to cool the reduced ore arriving there before it is discharged.

The carbon dioxide gas can also be taken from the pipe 37 be what from the pipes 13 as protective gas into the gasifier shaft i is initiated. In the carburetor it is advantageous to process fuel, which low in volatile matter and water, so that the water gas equilibrium adjusts on the basis of small amounts of water vapor.

Claims (1)

PATENT CLAIM: i. Process for the production of sponge iron by Reduction of iron ore by means of carbon monoxide and possibly hydrogen Gases at temperatures below the melting point of iron and iron ore, thereby characterized in that initially by gasifying a pulverulent fuel with Oxygen in a direction that does not serve to reduce ore is a reducing one Gas is generated, the content of carbon monoxide and hydrogen more than 70%, preferably is more than -50 / 0 and its temperature is essentially that of the reduction of the ore to Eisengchwarnm working temperature to be used, preferably about iooöJ-, corresponds, after which the reducing gas from the gasifier immediately is passed into the reducing device and there is brought into contact with the ore. Method according to claim i, characterized in that the gasification of the fuel with oxygen in the presence of endothermic media such as carbonic acid or Steam takes place. 3. The method according to claim (i and z, characterized in that that the generation of the reducing gas and the reduction of iron ore at high Pressure take place.