DE1266330B - Process for the continuous production of carbonaceous iron - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C21b

German class: 18 a -13/14

Number: 1266 330

File number: J 21343 VI a / 18 a

Filing date: February 23, 1962

Open date: April 18, 1968

The present invention relates to a method for continuous production of carbonaceous iron by reducing an iron ore in which the pre-reduction of the iron ore in a first reaction zone at a temperature below that the sintering temperature of this ore is carried out with a reducing gas that is made of a second reaction zone in which the reduction of the iron ore is completed. This The process consists in the final reduction by the introduction of cracked methane and oxygen is carried out in a liquid carbonaceous iron bath, with the gases introduced in the same Way like the prereduced mineral coming from the first reaction zone into the middle of the carbonaceous one Iron baths are introduced at a level below that of the surface of the bath, and the proportion of oxygen introduced below the amount of oxygen which causes the release of a substantial amount of carbon dioxide on the surface of the bath.

In U.S. Pat. No. 2,750,277, a method for reducing and melting Iron ores described, the reduction of the crushed iron ore in the solid state by a from a combustion of a gas or liquid fuel derived reducing gas carried out after which the reduced ore is simply melted.

In contrast, the inventive method for reducing iron ores consists of a combination of two process measures, namely firstly a pre-reduction of a finely comminuted iron ore in the solid state in a first reaction zone by reducing gases coming from a second reaction zone, and secondly a very strong reduction of the pre-reduced iron ore in a second reaction zone in the molten state by introducing a strongly reducing gas consisting of cracked methane into the liquid bath. The main differences of the process according to the invention from the reduction process described in the aforementioned USA patent are that, on the one hand, according to the invention a strong final reduction is carried out in the liquid phase, while according to the USA patent the reduced ore is simply melted in the final stage, and on the other hand in the fact that the gases fed in according to the invention have a significantly greater reducing power than the gases used in the process described in the above-mentioned USA patent, the ur process for continuous production
of carbonaceous iron

Applicant:

Institut Francais du Petrole des Carburants
et Lubrifiants,
ίο Rueil-Malmaison, Seine-et-Oise (France)

Representative:
Dr. F. Zumstein,

Dipl.-Chem. Dr. rer. nat. E. Assmann
and Dipl.-Chem. Dr. R. Koenigsberger,

Patent Attorneys, 8000 Munich 2, Bräuhausstr. 4th

Named as inventor:
Claude Clement, Bagneux, Seine;
Francois Eschard,
Croissy-sur-Seine, Seine-et-Oise (France)

a ₅ Claimed priority:

France of February 27, 1961 (854 184) -

initially consisting of carbon monoxide and hydrogen, already in a previous stage to one thorough iron ore reduction were used and therefore essentially only from Carbon dioxide. These gases only serve the purpose of melting the reduced ore To deliver heat. Because of the low reducing power of these gases, it is not possible, they lead to a strong reduction in the liquid phase in connection with a pre-reduction in the solid Phase to use because the reduction in the final phase of a reduction process due to the low Reaction speed made very difficult and only using extremely reducible Gases as used in the method of the present invention is to be carried out. The reduction method according to the invention, in which a natural gas (methane) cracked in a furnace directly is introduced into the molten molten bath, therefore, in contrast to that in the USA 2 750 277 described reduction process a better utilization of the reducing power of the used cracked natural gas as that is extremely

809 539/285

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Reducible gas in the final reduction zone, in which oxygen or cracked methane as carrier media maximum reducibility is required, introduced into the liquid carbonaceous iron bath liquid phase with the pre-reduced iron. However, it is also possible to do this in advance is, in addition to a more effective reduction ore delte by means of an inert gas stream or under the advantage is obtained that smaller amounts of gas 5 use mechanical conveyors required are. Above all, the better economic bath to supply.

borrowed utilization of the inventively used This type of implementation, which is due to the invented

th reducing gas is compared to the combination mentioned in the two successive USA. Patent specification described measures gender reduction stages is possible, offers numerous is a great advantage. io advantages compared to the usual for the

Another advantage of the melting process of the present invention in the form of fine particles is that the cracked natural gas used a reduced ore or oxide techneb its reducing effect also contributes to the thermal process.

generation serves, on the one hand to an out- In fact, as a result of the presence of

sufficient solid phase reaction rate to add dissolved carbon in the coal iron bath and on the other hand the metal produced together with the introduction of pre-reduced ore in the molten state. The inven- under the surface of the bath a contact of the fluid according to the direct introduction of a sedate iron oxide into the walls of the reactor went out of tune Amount of a mixture of methane and be avoided and thus a faster Oxygen in the middle of the molten bath is seen to decay as a result of the corrosive action of the lent the amount of heat given off by iron oxide to the bath at the temperatures at which that much more effective than when the same amount of gas is carried out. This advantage remains is burned and the flame obtained in the upper also exist in comparison to method surface of the bath to be heated, like those of the reduced iron oxide from a flame this in the case of the US Pat. No. 2,750,277 melted and in the liquid state in the above-mentioned Procedure is the case. It is therefore introduced area of the bath, because here too according to the invention consumes significantly less gas. contact between the liquid iron

As already mentioned, according to the invention the oxide and the walls of the reactor can only be avoided with difficulty by reducing iron ore in two steps. After all, that led to the invention. In the first reaction zone, the iron ore 30 according to the method compared to the latter, at a lower temperature than the sintered solution, has the advantage of a higher reaction temperature of the ore with a reducing gas, which is due to the fact that it is mainly composed of carbon oxide and what- the ore is introduced into the bath at a level which is made up of hydrogen and at least in part which is appreciably below the surface of the bath since the second reaction zone originates. The ore or oxide is preferably distributed much more evenly through the bath at a temperature between 500 and 700 ° C, while the reduction of the oxide introduced on the first reduction is carried out for as long as the surface of the bath is reduced by the degree of reduction at least 70% of the ore is scattered, which considerably limits the reaction rate and a maximum of 98%, preferably 90 to 98%, speed,
wearing. The mineral that originates from the first reaction zone can be treated with the process according to the invention, together with cracked, probably pure, ores such as methane and oxygen only consisting of iron oxide, for the final reduction in the middle, and ores that contain impurities from a carbonaceous iron bath and hold, and especially Gangstein. In the latter, although at such a height that is below the upper case, it is particularly advantageous to have a known area of the bath. To add the supplied oxygen 45 flux, the acidic or basic properties of which is regulated in such a way that it is below the oxygen-sic quality depending on the amount selected to release an essential composition of the gangue stone, the amount of carbon dioxide on the surface of the bath being the Flux before the first stage, effected in the course. The same or even after the introduction of the pre-carbon-containing iron, which occurs in this final reduction zone, is introduced into the metal bath in an amount of reduced ore which corresponds to the amount of iron that can be in the form. Which is supplied by the carbon of the metal bath of the partially reduced ore. unreduced impurities then accumulate in

The degree of reduction is the pro-form of slag on the surface of this bath, The first reduction stage can be carried out in or in

tion was withdrawn. _{For example, an iron ore Fe 2} O ₃ reduced by 80% over several successive phases has an average, e.g. B. in one or more reactors, borrowed composition that corresponds to _{FeO 03.} in which the ore is cheap in countercurrent to the gas

It is desirable that electricity can circulate under the conditions.

The temperature of the ore is increased in the course of the first reaction stage

Deposition on the reduced iron ore if possible 60 first process stage, preferably on a stand To allow far to progress, since the carbon is kept deposited, in which a substantial sintering of this tion in particular offers the advantage that the inclination of the ore is avoided and at the same time a satisfactory ore particles to reduce agglomeration and slow reaction speed is achieved. Except those Termination of the reduction in the liquid when the benefit is to be taken advantage of bathroom of the last stage to facilitate. 65 result from the deposition of carbon on the

After completion: the first reduction stage results in ore, the ore is advantageously on one the partially reduced ore is kept in a finely divided state at a relatively low temperature, e.g. B. before and can, for example, using between 500 and 700 ° C, either during the

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the entire course of this first stage or only while a temperature was brought which is equal to or

end of the second part of the same. is much higher than the one at which this first

The oxygen, e.g. B. in the form of air, as well as the reduction stage is carried out,
cracked methane, e.g. B. in the form of cracked It is generally advantageous to carry out natural gas, as well as the prereduced ore, in 5 tion of the process the various used the carbonaceous iron bath are introduced in a gases and solids to preheat and the heat of the appreciably below the surface The various products located in the bath, which from the reduction level, so that the gas and the solids escape at the same time, can be moderately distributed in heat exchangers inside the bath. to win back.

The temperature of the iron-carbon bath becomes higher due to the equal distribution of the reduction chosen as its solidification temperature, that of that of the reactor in which the first reduction content of the bath depends on carbon. stage is carried out, escaping gases are not

In practice one will be completely oxidized at a temperature ar- it may be advantageous to

work, which is considerably higher than the so determined from it in the known manner the carbonic acid gas and

Minimum temperature, so that on the one hand any untimely 15 to remove the water vapor and then again

Solidification is avoided, which can circulate from one to the same reactor,

Due changes to the composition of the bath The following examples, which are not intended to be limiting

can result, and on the other hand, the bathroom can be seen in a kend, explain the application of the

good fluid condition is maintained. Method of the present invention. It understands

If you have a mixture with a carbon content of 20 that, according to these examples, all movements

almost the eutectic composition (4% of the solids and gases are continuous that

Carbon) corresponds, with a suitable slag, to the specified substance quantities of production

used, one can correspond to one ton of coal iron per unit of time at a relatively low temperature

work temperature, e.g. B. between 1200 and 1300 ° C, and that the gas volume at normal temperature

and at the same time a high reduction rate and pressure conditions are specified (temperature

maintained. of about 20 ° C and atmospheric pressure of

The carbon-containing iron can be periodic or 760 mm of mercury).

continuously, e.g. B. be deducted at one point These examples are shown in the drawing by the

the one on which there are neither partially reduced ore particles shown in FIGS. 1 and 2.

with it still carries slag particles, if slag 30 F i g. 1 represents a reduction in which only one

is used. It is therefore advantageous to set the deduction only reduction phase for the first stage.

opening for these products as far away as possible and in which the products from this phase

Lich is burned from the introduction openings for the pre-reducing partially oxidized gas to

decorated ore and to attach the gas. Heat for the heat exchanger used

The oxygen and possibly the reduction 35 supply.

Gas quantities are chosen so that they are sufficient. Fig. 2 shows a reduction with two reductions at the same time the final reduction of the ore, its karbu phases in the first stage, in which the two phases originating from this ration and the maintenance of the temperature, partially oxidized coal iron bath to be brought back into circulation to their original gases.
Stand, preferably without additional heat, at 4 ° Ti ■ '1 1
to back up. This condition assumes that the egg spit
The surface of the bath exhausting gases consist only of 1.41 powdered iron oxide, which is roughly composed of CO and H ₂ . Such a result can _{correspond to the formula Fe 2} O ₃ and can easily be achieved beforehand to a temperature according to the invention without bringing the temperature to 700 ° C., which makes it necessary to use excessively large amounts of gas, and line 2 into the reactor 1 (Fig. 1) introduced, although this is made possible by the fact that the ore of a pre-reduction of 70 to 98% under-direction 1885 m ^{3 of} reducing gases are fed through the line 3 in the opposite direction, which was drawn in the. essentially consists of hydrogen and carbon

The possibility of standing in this way immediately without having to stand in the heat exchanger 4 beforehand

additional heat from outside, cast iron or carbon was heated to a temperature of 650 ° C. That

Obtaining fuel steel represents a significant ore reduced to approximately 80% by the

Advantage is that conveyed in a substantial simplification line 5 in the furnace 6, where it is through the

the means for carrying out the process previously cracked in the furnace 12 and at a

is expressed, and in the possibility of a temperature of 1000 ° C through the line 11 to

the avoidance of any heat transfer corresponding to the natural gas flow guided out into the molten bath 7-

to prevent the corresponding energy losses. It's left over. The volume of the cold natural gas,

Alternatively, this cast iron or this carbon can be introduced into the furnace 12 through the line 13

Altering steel by making different ones, will reach 917 m ³ . At the same time, 419 m ³

the person skilled in the art adds additives, so that oxygen in the heat exchanger 8 on

one z. B. Special steels received. 6 ° 1000 ° C was heated and from the line 10

A heating by combustion of gas comes over, through the line 9 in the furnace 6.

the bath, which leads to the effluent from the bath.

Gases would be contaminated and therefore unsuitable. The casting is carried out periodically or continuously

would be to reduce the ore correctly, the casting hole 14 is deducted. The ones from the weld pool

present invention excluded. ⁶ 5 through line 15 at a temperature of un-

In the course of the first reduction stage it is around 1500 ° C flowing gases that are generally not useful to add additional heat to 1835 m ^{3 of} hydrogen and 880 m ^{3 of} carbon oxide, at least not if the ore is up beforehand Part (1885 m ³ ) in the heat

exchanger 4 and partly (830 m ^s ) in the line 16 passed . The latter part is available for heating the furnace 12, the heat exchanger 8 and the ore 2.

The gases flowing out of the reactor 1 through the line 17 have a high content of fuel gases and can either be burned as they are or after the carbonic acid gas 18 ″ and the water vapor 18 δ contained therein have been removed in the device 18 in order to generate heat. ίο far. For this purpose, they are passed through line 19 into the various heat exchangers.

In the heat exchanger 4, which contains the cooling circuit 20-21 , the heat of the reducing gases cooled from 1500 ° C. to approximately 650 ° C. is recovered. In contrast, the furnace 12 and the heat exchanger 8 are heated by the circuits 24-25 and 22-23, respectively.

Example 2 _ao

One shown in FIG. 2 , which contains two different reduction zones 27 and 28, is used and 1.41 pulverized iron oxide, which _{corresponds approximately to the formula Fe 2} O ₃ and was previously heated to a temperature of 700 ° C., into zone 27 through the Line 29 introduced.

At the opposite end of the zone 27 , reducing gases consisting mainly of hydrogen and carbon oxide are fed in through the lines 30, 31 and 32 at a temperature of 650 ° C. The ore, reduced to 88%, is directed in the direction of arrow 33 into zone 28 of furnace 26 , where it encounters a stream of carbon oxide and hydrogen supplied through line 34. In this zone, carbon is deposited on the ore without the degree of reduction of the ore being significantly changed. The ore is then passed through the line 35 into the furnace 36, where it is pushed into the molten bath 37 by the methane stream previously cracked in the furnace 42 and fed through the line 41 at a temperature of 1000 ° C. The volume of cold methane introduced into furnace 42 through line 43 reaches 585 m ³ . At the same time, 281 m ^{3 of} oxygen, which comes from the line 40 and has been heated to 1000 ° C. in the heat exchanger 38, is introduced into the furnace 36 through the line 39.

The casting is withdrawn through the casting hole 44 periodically or continuously. The gases flowing out of the molten bath through line 45 at a temperature of approximately 1500 ° C., consisting of approximately 628 m ^{3 of} carbon oxide and 1170 m ^{3 of} hydrogen, pass through the heat exchanger 46, which they leave again at a temperature of 650 ° C. and flow partly (580 m ³ ) into line 30 and another part (1218 m ³ ) into line 34.

The gases flowing out of the zone 28 of the furnace for the prereduction are fed through the line 32 to the zone 27 of the same furnace. The gases coming from the zone 27 flow through the line 47 into the unit 48, from where they flow out again through the line 51 after cooling and removal of the carbonic acid gas 49 and the water 50 contained therein. A portion of this (approximately 1120 m ³ ) is discharged through line 52 and burned to heat the heat exchangers. The other part (677 m ³ ) flows through line 53 into heat exchanger 46, from where it comes out again through line 31 at a temperature of approximately 650 ° C.

Oven 42 and heat exchanger 38 are heated by circuits 56-57 and 54-55, respectively.

From a comparison of Examples 1 and 2, the essential savings in methane can be seen, which are from the simultaneous implementation of an accelerated pre-reduction and a subsequent pre-carburization results.

Example 3

1.41 ore, which is the same as that mentioned in Example 2, is reduced in a furnace 26 which contains two different reduction zones 27 and 28, the temperatures of which are kept at 650 and 550 ° C., respectively.

The degree of reduction of the ore reaches 81% at the exit of zone 27 and 94.5% at the exit of zone 28.

The reduction is terminated in furnace 36 by carbon deposited on the ore in zones 27 and 28.

Thereby it is unnecessary to introduce cracked methane into the furnace 36. Only 151 m ^{3 of} oxygen heated to 1000 ° C are fed into this.

The gases flowing out of the furnace 36 then consist mainly of carbon oxide. They are then fed into zone 28 at the same time as 1946 m ^{3 of} reducing gas, the origin of which is specified below.

Independently of this, 1914 m ^{3 of} reducing gas are fed to zone 27 , the origin of which is specified in detail below.

Part of the gas separated from the zones 27 and 28 serves to preheat the ore, while the remaining part is treated in a known manner in order to remove the water and the carbonic acid gas therefrom. In this way, a total of 2840 m ^{3 of} reducing gas is recovered, which mainly consists of carbon oxide and hydrogen.

This gas is then returned to zones 27 and 28, at the same time as fresh gas that comes from the partial combustion of 341 m ^{3 of} natural gas using 175 m ^{3 of} oxygen. In this way, ^{1914 and 1946 m 3 of} reducing gas are fed to zones 27 and 28, respectively, at a temperature of 650 ° C., as indicated above.

The reducing gas is preheated by burning a total of 50 m ^{3 of} natural gas in the heat exchangers.

Claims (3)

Patent claims: 1. Process for the continuous production of carbonaceous iron by reduction of an iron ore, in which the pre-reduction of the iron ore in a first reaction zone occurs a temperature which is below the sintering temperature of this ore, with a reducing gas is carried out from a second reaction zone in which the reduction of the iron ore is brought to an end, originates, thereby characterized that this final reduction by introduction of cracked methane and Oxygen is carried into a liquid carbonaceous iron bath, the introduced Gases in the same way as the pre-reduced mineral originating from the first reaction zone be introduced into the center of the coal iron bath at a level below it the surface of the bath is located, and the proportion of oxygen introduced below the Amount of oxygen lies in the release of a substantial amount of carbon dioxide on the surface of the bath. 2. The method according to claim 1, characterized in that the first reduction at a 10 Temperature between 500 and 700 ° C is carried out. 3. Process according to Claims 1 and 2, characterized in that the degree of reduction the first reduction carried out in the solid state is between 90 and 98%. Considered publications:
U.S. Patent No. 2750 277. 1 sheet of drawings