WO2011131433A1

WO2011131433A1 - Bentonite-bonded pressed articles from fine-grain oxidic iron carriers

Info

Publication number: WO2011131433A1
Application number: PCT/EP2011/054214
Authority: WO
Inventors: Christian Boehm; Hado Heckmann
Original assignee: Siemens Vai Metals Technologies Gmbh
Priority date: 2010-04-19
Filing date: 2011-03-21
Publication date: 2011-10-27
Also published as: CN102918169A; JP2013525605A; AT509072B1; CA2796688A1; MX2012012186A; BR112012026713A2; KR20130058693A; AT509072A4; AU2011244599A1; US20130032005A1; RU2012148808A; EP2561107A1

Abstract

The invention relates to a method for producing iron-oxide-containing pressed articles from fine-grain oxidic iron carriers by producing a mixture which comprises fine-grain oxidic iron carriers, bentonite as a binder, and water, pressing the mixture, and curing the green pressed articles obtained during the pressing, as well as to pressed articles produced by the method and to the use of the pressed articles as lumpy iron carriers. According to the invention, after the components of the mixture have been assembled, said mixture is subjected to a kneading process of at least 3 minutes and up to 30 minutes, which is followed by the pressing. The pressed articles are produced without any souring process.

Description

description

Description of the Invention Bentonite-bonded compacts of undergrained oxidic iron carriers

Field of engineering

The present invention relates to a process for producing iron oxide-containing compacts from lower-grained oxidic iron carriers by preparing a mixture comprising lower-grained oxidic iron carriers, bentonite as binder, and water, pressing the mixture, and curing the green compacts obtained in the pressing, as well as by the method produced compacts and the use of

Compacts as lumpy iron carrier.

State of the art

In many processes for producing sponge iron, in which a

Direct reduction shaft with fixed bed is used, for example after the

MIDREX® or HYL® processes, or in smelting reduction processes for the production of molten pig iron, which are reduced in a shaft, such as in the COREX® process, lumpy oxidic iron carriers, such as lump or pellets, are to be used as starting material. Through transport and handling, the lumpy oxidic iron carriers suffer abrasion or can break. The products of such degradation are for use in one

Direct reduction shaft with fixed bed too fine, since they reduce the total gas permeability of a fixed bed and increase the risk of maledistribution of the reduction gases or of channeling with associated partial incomplete reduction. Before charging into a direct reduction shaft with a fixed bed, separation of undersized particles of oxidic iron carriers from the lumpy oxidic iron carriers must be carried out by screening and / or screening, for example by screening at a particle size of 6.3 mm and sighting at one Particle size of <200 μηη.

The term undersize is to be understood as meaning particles whose particle size is less than 10 mm, preferably less than 6.3 mm, particularly preferably less than 5 mm. Give it these values are the width of the mesh of the sieve used for screening, through which the undersize falls.

The particle size of undersize is called undersized. In order to use the undersize, it must be converted into a lumpy form, that is to say agglomerated.

If there are sintering or pelleting plants in the vicinity, it makes sense to use these facilities for agglomeration of undersize. Often in the

Plant network also cold briquetting plants for briquetting of the undersize available. The undersize of the lumpy oxides is in some cases by return freight for

Returned ore suppliers.

Agglomeration processes for converting finely particulate material into particulate form, such as pelleting or sintering, can only be operated economically on a large scale. Therefore, an agglomeration is often omitted and the undersized particles from the degradation of the lumpy oxidic iron carriers are stored up unused.

Summary of the invention

Technical task

The object of the present invention is to provide a method for transferring the undersize into lumpy form, which is the undersize for a

economic exploitation for the production of sponge iron or liquid pig iron.

Technical solution

This task is solved by

Process for the production of iron oxide-containing compacts from lower grained

oxidic iron carriers by producing a mixture comprising the lower-grained oxidic iron carriers, bentonite as binder, and water, pressing the mixture, and hardening the green compacts obtained in the pressing into compacts, characterized in that the mixture after combining their components at least one minutes, preferably at least 5 minutes, up to 30 minutes, is preferably subjected to up to 20-minute, more preferably up to 15-minute kneading, followed by the pressing.

The pellets are agglomerates of fine particulate matter made by compression. Examples of forms of compacts are briquettes, tablets and slugs or strands, or by gentle deagglomeration of slugs or strands produced lumpy fragments.

The advantage of producing compacts from the lower-grained oxidic

Iron carriers over pelleting is that making compacts, such as briquetting, is more flexible to variations in quality and

Quantity of feedstocks can respond, and can be dispensed with a preparation of the feedstock by fine grinding and the burning of green pellets. The production of compacts, such as a briquetting, therefore, is in principle better suited for processing undersize, which is obtained in quantities of up to 100,000 t / a.

The binder used is bentonite. Bentonite is a material which is a mixture of various clay minerals and contains as its main constituent smectitic phyllosilicates, preferably montmorillonite. The smectite

Phyllosilicates, preferably montmorillonite, are present in amounts of at least 60%, preferably at least 70% by weight. In this case, the bentonite may be a naturally occurring rock, or modifications obtained by adding additives or carrying out process steps, of course

occurring rock.

Among the lower-grained oxidic iron carriers are, for example, dusts that occur in the Möllerung of lumpy oxidic iron carrier to understand. Preferably, the mixture comprises 3 to 12% by weight of bentonite, based on the amount of the lower-grained oxidic iron carriers, preferably 6 to 10% by weight.

With less bentonite, no sufficient effect as a binder is ensured. With more bentonite, the additional consumption of bentonite does not give any appreciable benefit in its action as binder in the compact. In addition, the processing of the pellets in a steel mill is increased due to the higher content of bentonite Slag formation difficult. In addition, a higher proportion of bentonite represents unnecessary ballast during transport of the compacts.

The components of the mixture can be in one or more steps

be merged. For example, first the solid components of the mixture can be brought together and premixed before admixing

Water for setting a doughy consistency takes place. The doughy mixture of all components is then subjected to the kneading process.

However, the solid and liquid components of the mixture can all be combined in one step.

The kneading process lasts at least 3 minutes, preferably at least 5 minutes, up to 30 minutes, preferably up to 20 minutes, more preferably up to 15 minutes, the limit values being included in each case. With a duration of less than 3 minutes, the properties of the obtained green compacts and compacts are insufficient. With a duration of over 30 minutes, no significant change in the properties of the

Green compacts and pellets achieved, however, the time saved against mauken decreases with increasing duration of the kneading process.

Advantageous Effects of the Invention

When using bentonite as a binder, it is common to use the bentonite and water

comprehensive mixture, and especially the bentonite, several hours at rest

Allow to swell storage - a process that is also called Mauken - to unfold the binding capacity of the binder bentonite. The duration of the Maukens is called Maukzeit.

The kneading process to be carried out according to the invention, to which the mixture is subjected after the components have been combined, makes it possible to dispense with the time-consuming masonry without any appreciable deterioration or even with an improvement in the properties of the compacts. This reduces, for a given throughput, the space required for this treatment step (bunker or heap volume), or for a given storage size, a higher throughput can be achieved. In addition, the mixture - and thus the structure of the final product Pressling - evened out, which for a certain

The quality of binder necessary to reduce the quality of binder can be reduced. Table 1 shows the evaluation of tests for the production of compacts with regard to the drop resistance (SF) and the puncture strength (PDF) of the pellets during a test campaign. The pellets are after the

Process according to the invention with kneading process, or manufactured according to the prior art with Mauken. The compacts are briquettes.

The drop strengths of green compacts produced according to the invention and

Compacts and mauve green compacts and compacts - each with the same starting materials and under otherwise identical conditions - are of the same order of magnitude, both for green compacts and for air-dried and thermally dried compacts.

By the process according to the invention produced compacts and green compacts show in comparison to maucene-produced compacts and green compacts - each with the same starting materials and otherwise the same conditions - an increase in the dot crush strength, especially in compacts produced by thermal drying.

The behavior of the compacts with respect to point compressive strength after thermal drying as an indication of the behavior of the compacts after charging in a

Reduction zone considered. The compacts produced according to the invention are, due to their punk pressure resistance properties, much better suited for use in an industrial reduction process than compacts produced with mauves. As a subgrained oxidic iron carrier, sinter feed from the Fabrica mine in Minas Gerais State, Brazil (FERTECO) was used for all the tests shown in Table 1. The grain size used to make the compacts was 0-8 mm with a d50 of 0.75 mm and a d95 of 3.15 mm. For setting constant

Experimental conditions, the sintering feed was thermally dried before the experiments to <1% humidity.

The following commercially available bentonites were used:

IK = IKO Bond ^D® (activated calcium bentonite from IKO Erbslöh with approx. 90% montmorillonite) VO = VOLCLAY ^® (natural sodium bentonite from Süd-Chemie with approx. 70-80% montmorillonite

Tl = TIXOTON ^® (activated calcium bentonite from Süd-Chemie with 70% montmorillonite)

CA = calcigel ^® (natural calcium bentonite from Sud-Chemie)

The mixtures were produced in a batch mixer of the type FM130D from Lödige. The kneading machine from Köppern used for kneading purposes consisted of a vertical cylindrical container, through which a centrally rotating shaft with kneading arms is guided.

An optionally performed heating of the kneader for supplying heat to the mixture during the kneading process took place via the housing, for which saturated steam of 6 to 8 bar was available.

The production of the green compacts was carried out by means of a trial roller press type 52/10 from Köppern. The selected pillow-shaped format for the green compacts had a nominal volume of 20 cm ³ . The task of the material to be pressed was done by means of gravitational arbiter. From the experimental roller press associations were made consisting of several green compacts. These associations contain green compacts both in the margins of the associations and in the middle of the associations.

In order to obtain individual green compacts or individual compacts for determining the fall resistance or the point compressive strength, the bandages are broken along the dividing seams between the individual green compacts. As a rule, the associations break up during discharge from the trial roller press into individual green compacts. When producing the compacts according to Table 1, the bentonite (bent) and then water (W) were added to the lower-grained oxidic iron carrier - the mixing time was 2 minutes in each case. The percentages for bentonite and water are percent by weight; the percent by weight refers to the amount of undergrained oxidic iron carriers used in each experiment. Following the mixing process, the mixture was kneaded in the kneader for the production of inventive compacts. If necessary, heating of the kneading plant was carried out, specifically an indirect heating via the housing. Results thus obtained are indicated in Table 1 by the entries Knead + H. in the treatment column, where H. is for heating. Entries Kneading - H. in the column treatment mean that there is no heating of the kneading unit.

To make compacts under mauves, the mixture was allowed to rest in a Mauc container following mixing.

After the kneading process in the kneader or the Mauken in Maukbehälter the mixtures were subjected as a material to be pressed a pressure in the experimental roller press to produce green compacts.

The resulting green compacts are still soft - which is indicated in the jargon by the word "green" - and are subjected to curing to arrive at the finished compact This curing, for example, by at least partial drying by storage in air and / or a After pressing, individual green compacts were examined directly for impact (SF) and puncture resistance (PDF) in green, in technical jargon The results of these investigations are shown in columns SF green and PDF green.

Fall and dot compressive strength measurements were repeated after air curing for 1 hour and air curing after 24 hours and 72 hours, respectively. The results of these investigations are shown in the columns "SF n. 24 h (72 h) ^* " and "PDF n. 24 h (72 h) ^* ".

A subset of the green compacts obtained in the respective experiments was dried at 290 ° C. for 30 minutes and, after cooling in air, likewise examined for drop resistance and point compression strength. The results of these investigations are shown in columns "SF drink" and "PDF drink". shown.

In the fall test (based on ASTM D440) for determining the fall resistance, a 4 kg sample of green compacts or compacts cured by drying in air or by thermal drying is passed through a downpipe four times from a height of 2 m plunged into a collecting container whose bottom is formed in the form of a solid steel plate. The drop tube has a diameter of 200 mm and the collecting container has a diameter of 260 mm. The thickness of the steel plate is 12 mm. The evaluation of the fall test by sieve analysis takes place after the second and fourth fall. The numerical values in Table 1 indicate in each case the fraction of the grain fraction> 20 mm after four falls.

For the determination of the dot compressive strength, a type 469 testing machine from ERICHSEN was used. In this test method individual green compacts or hardened by drying in air or by thermal drying compacts clamped between two conditions, of which the lower is coupled to a load cell and the upper is continuously tracked by spindle drive for applying a creeping swelling pressure load. The lower edition is formed by a round plate of 80 mm diameter and the upper by a horizontal round iron of 10 mm diameter. The

Feed rate for the upper support is 8 mm / min. The

Dot crush strength is recorded as the maximum load bearing of a green or cured compact prior to breakage - the entries in Table 1 indicate the average dot crush strength at break due to dot pressure loading in Newton. In each case, six green compacts or compacts from the middle region and six green compacts or pellets from the edge region of the bandages obtained in the trial roller press were examined. Out of those

Averages were calculated for the data obtained, with the minimum and maximum values being disregarded. The mean values are given in Table 1.

Table 1

DESCRIPTION OF THE EMBODIMENTS Another object of the present invention is according to the

According to the process of the invention obtained compact and the use of a compact obtained by the process according to the invention as lumpy oxidic iron carrier for the production of sponge iron or liquid pig iron. The

Production of sponge iron may, for example, take place in a reduction shaft, a rotary hearth or a rotary kiln, the sponge iron being able to form an intermediate for the production of molten pig iron in a smelting reduction process by means of a melter gasifier. This may also be smelting reduction Direct reduction compound plants or direct reduction coal gasification Verbundanlagen act.

The use of the compacts is carried out in this use in the same way as the use of other types of lumpy oxidic iron carrier.

According to a preferred embodiment of the method according to the invention, the mixture also comprises iron-containing metallurgical residues, such as metallized Fe-fines, scale such as mill scale, metallurgical dusts such as blast furnace dust or converter dust or BOF ejection or metallic

Slag fine dust or EAF ejection or EAF dust, sludge such as

For example, blast furnace sludge or BOF sludge or hot rolling mill sludge, fine iron, iron filings.

Optionally, such material originating from dedusting facilities or scrubbers is subjected to a conditioning step for the enrichment of iron before it is used according to the invention for the production of compacts.

Preferably, the mixture comprises at least one member of the group

metallized Fe-Fines,

scale,

Metallurgical dusts,

- sludge,

Material which originates from a process for the production of steel, in which iron sponge and / or pig iron obtained using pellets produced according to the invention are used.

In this case, it is also included, for example, that lower-grained material screened off by the sponge iron is used.

It is also included, for example, that at a take place, for example, for maintenance reasons, decommissioning of an aggregate for the production of

Sponge iron and / or pig iron - for example, a direct reduction shaft or a melter gasifier - resulting material is used after a screening.

The term metallized Fe-fines is to be understood as meaning fine-grained metallized iron (Fe) supports, with fine-grained particle diameters of up to 6 mm being meant. Preferably, the iron-containing metallurgical residues have a combined content of iron and of carbon, which is above 50% by weight. From which

combined content of iron and carbon use in one

method of the invention is economically useful, however, depends on the accumulating Amount of iron-containing metallurgical residues and landfill costs for such iron-containing metallurgical residues. Preferably, this material is used, which originates from a process for steel production, in which obtained using pressed bodies according to the invention

Iron sponge and / or pig iron is used. That way they can

Smelter residues are recycled in the process leading to their formation. Such recirculation is worthwhile, as metallurgical residues - such as metallized

Fe fines, scale, metallurgical dusts, metallurgical sludges -, high levels of iron and / or carbon, and the recycled materials need not be deposited costly. In the reduction process, the iron contained in the smelters leads to the saving of iron ore and the carbon to the reduction of reducing agent.

Certain metallurgical residues, especially scale, fine iron, iron filings, due to their grain shape or their mechanical properties act as structurally reinforcing components in the compact by mechanically increasing the force required to destroy the compacts by internal friction. The greater this effort, the greater the strength of the compact. The structure-enhancing effect is expressed in an increased strength of the compacts. The consideration of the strength is usually differentiated according to cold strength, which indicates the strength at room temperature, and hot strength, which indicates the strength at a - defined by the respective set test conditions - compared to room temperature increased temperature. In addition to an improvement in the cold strength of

Pressings due to iron-containing metallurgical residues can also improve the hot strength of compacts - in particular under the conditions given during the reduction - by iron-containing metallurgical residues. The in some

Hütten residual materials contained carbon, for example, when heating the

Presslinges initiate reduction reactions within the compacts, which in turn has an increase in the hot strength of the compact.

With a common use of lower-grained oxidic iron carriers and metallurgical residues for the production of compacts, therefore, the compacts receive additional strength. Therefore, Binder - which is indeed present to provide strength in the compact - saved and thus the entry of inert substances

or slag formers are limited in the compact. In terms of quantity, the mixture may comprise the iron-containing metallurgical residues in an amount of up to 100% by weight, based on the amount of the lower-grained oxidic iron carriers. According to a further preferred embodiment, the mixture also comprises feinteilchenformiges hematitic and / or limonitisches material, whereby by fine particle-shaped a particle diameter of less than 6mm is to be understood.

In the case of the presence of oxidic material which is difficult to reduce in a reduction process, in particular in the form of magnetite, problems of reduction kinetics associated with such material can be overcome by rendering the hardly reducible material - in the present example in the form of magnetite - fine-particle-like Reduction process easily reducible

Material - especially in the present case in the form of hematite or limonite - is mixed. In the sense of the Austrian patent specification AT399887 an improvement of the reduction kinetics is to be expected by this mixture.

Feinteilchenformiges reducible material falls in plants for the reduction of oxidic iron carriers by means of a reducing gas, for example plants for carrying out processes for the production of sponge iron, in which

Direct reduction shaft with fixed bed is used, for example after the

MIDREX® or HYL® process, or in smelting reduction processes for the production of molten pig iron, among other things in the form of dust or sludge

Dedusting facilities or scrubbers for dedusting top gas, from

Reducing gas or of generator gas.

Use of this material increases the economics of a process for producing sponge iron or molten pig iron due to the recirculation of material into the process loop. For reasons of process economy, it is preferred that the mixture for producing iron oxide-containing compacts also in the dedusting of top gas, reducing gas, or generator gas of a plant for the reduction of oxidic iron carriers by means of a reducing gas resulting feinteilchenformiges material.

Topgas means a gas which, after fulfilling its requirements, is

Reduction task with respect to the oxidic iron carrier from the filled with oxidic iron carriers aggregate, in which it has fulfilled its reduction task is deducted. For example, in the case of a direct reduction in one Direct reduction well, Topgas is the gas that is discharged from the direct reduction well.

Generator gas is to be understood as meaning a gas which is used in a melter gasifier or in a coal gasifier for producing a direct reduction of iron ore

gas to be used - is formed by gasification of carbon carriers in the presence of oxygen. In smelting reduction process, such a generator gas is cooled and dedusted before being used as a reducing gas for the reduction of oxidic iron carriers to an optimum reduction temperature.

Reduction gas is the gas used to reduce the oxidic iron carriers, whereby it is itself oxidized.

Mud obtained from scrubbers by scrubbing is produced by treating the waste water from the scrubber, with any washed-out dust settling as sludge. This sludge is withdrawn and prepared by at least partial dewatering for use according to the invention. Optionally, the dewatering may also include thermal drying.

If sludge is present in the lower-grained oxidic iron carrier, bentonite as binder, and water-comprising mixture of the process according to the invention, the water of the mixture can be at least partially introduced into the mixture by means of the sludge. Accordingly, the degree of dewatering of the sludge is selected.

According to a preferred embodiment, a heating of the mixture takes place during the kneading process. This can be done for example as indirect heating through the housing of the kneading, or as direct steam heating.

A comparison of experiments no. 1 and no. 4 in Table 1 shows that heating the mixture during the kneading process has positive effects on significantly increased dot crush strength.

In principle, by the method according to the invention, the undersize and in process steps in the steel production of pig iron material - such as DRI - resulting fine particulate material for the production of pig iron and steel can be developed. By recycling material, the raw materials are converted into a higher proportion in a final product and thus in fact cheaper. Landfill or return freight costs previously for undersize and others in the invention There is no longer any need to pay for the production of materials used by presses from DRI, pig iron or steel producers.

In addition, the method according to the invention has the advantage of reaching the compacts faster than in the case of the tufts.

Examples

With reference to the following exemplary schematic figures

Embodiments of the present invention explained in more detail.

Figure 1 shows schematically an embodiment of the present invention using the example of a direct reduction plant.

Figure 2 shows schematically an embodiment of the present invention using the example of a smelting reduction plant.

FIG. 1 shows a direct reduction plant schematically. There are pieces of oxidic iron carrier 1 in a direct reduction shaft 2 with a fixed bed by a

Reduction gas 3 reduced to direct reduced iron (DRI). The DRI is supplied to a consumer after passing through a compacting device 4 as hot briquetted iron (HBI). From the direct reduction shaft 2 executed top gas is released in a dedusting device 10, here a gas scrubber, from its dust load. From the oxidic iron carriers 1 is before the

Charging their lumpy proportions 1 a in the direct reduction shaft 2, a lower-grained fraction 1 b, which is not suitable for use in direct reduction shaft 2, separated by sieving on a sieve 5. In Figure 1, the sieve is immediately before

Direct reduction shaft 2 arranged; In principle, it may of course be located at any point on the input path for oxidic iron carriers. This subgrained fraction 1 b is, optionally after a breaking process in a in Figure 1 from

For reasons of clarity not shown breaking device of a mixing device 6 supplied. In the mixing device 6, the lower-grained fraction 1 b with bentonite as a binder 12, with unterkörnigem material 7, which is obtained in the compacting device 4 downstream HBI screening device 8, with residues from a steel plant 9 - in the present case metallized Fe-fines and scale -, as well as with

Mud 19 from the dedusting device 10, and mixed with water 1 1. The enumerated components of the mixture produced in the mixing device 6 become merged in two steps. Namely, first in a first step, the solid components of the mixture - bentonite as a binder 12, undersized material 7, residues from a steel plant 9, sludge 19 from the dedusting 10 - combined and premixed, before in a second step, an admixture of water 1 takes place to set a doughy consistency. The mud 19 from the

Dust removal device 10 is dewatered prior to assembly and thermally dried, which is not shown separately graphically for reasons of clarity. After the combination of the solid components of the mixture in a first mixer of the mixing device 6, the admixture of water 1 1 takes place in a second, the first mixer downstream mixer. The dough-like mixture is kneaded intensely in a kneader 13 for 15 minutes.

Thereafter, the kneaded mixture is fed to a pressing device 14. The product of the pressing in the pressing device 14 are still soft green compacts. The hardening of these green compacts takes place by storage in air on a

Bearing 15 at least partially dried and thus hardened to compacts. After their hardening so obtained, the pressed pieces obtained in the curing are the

Direct reduction shaft 2 supplied. In the direct reduction shaft 2, the

According to the invention produced compacts in the same manner as the lumpy portions 1 a of the oxidic iron carrier,

FIG. 2 shows a smelting reduction plant schematically. Elements of FIG. 2 comparable to FIG. 1 are given the same reference numerals as in FIG. Lumpy fractions of oxidic iron carriers 1 are charged into a smelting reduction unit 16. The smelting reduction unit 16 comprises a melter gasifier in which carbon carriers are gasified in the presence of oxygen 20 to obtain a reducing gas. The reducing gas is passed into a shaft which contains the lumpy portions of the oxidic iron carrier 1. As it flows through this shaft, an at least partial reduction of the lumpy portions of the oxidic iron carriers takes place. The so pre-reduced material is then in the

Melt carburetor introduced, there completely reduced and melted. The resulting molten pig iron 17 is tapped from the melter gasifier. From the smelting reduction unit 16 executed top gas 18 is in a

Dust removal device 10, here a gas scrubber, freed of its dust load. At a take place for the production of cooling gas wet dedusting of generator gas from the melter gasifier sludge is as well as the mud 19th used, which is not shown for reasons of clarity

From the oxidic iron carriers 1 is before the charging of their lumpy portions 1 a in which the smelting reduction unit 16, a lower-grained fraction 1 b, which is not suitable for use in the smelting reduction unit 16, separated by screening on a sieve 5. This subgrained fraction 1b is, if appropriate, fed to a mixing device 6, optionally after a crushing operation in a crushing device not shown in FIG. 2 for reasons of clarity. In the mixing device 6, the lower-grained fraction 1 b with bentonite as a binder 12, with residues from a steel plant 9 - in the present case metallized Fe-fines and scale -, as well as with sludge from the dedusting device 10, and mixed with water 1 1. The enumerated

Components of the mixture produced in the mixing device 6 are combined in two steps. Namely, first in a first step, the solid components of the mixture - bentonite as a binder 12, unterkörniges material 23,

Residues from a steel mill 9, sludge 19 from the dust removal device 10 - combined and premixed, before in a second step, an admixture of water 1 1 takes place to adjust a doughy consistency. The mud 19 from the

Lagerplatz 15, where the green compacts are at least partially dried and thus hardened to compacts. After their curing has taken place, the compacts obtained during curing are fed to the smelting reduction unit 16. In the

Smelting reduction unit 16, the pressed bodies according to the invention are reacted in the same manner as the lumpy portions 1 a of the oxidic iron carrier. List of reference numbers

1 oxidic iron supports

2 direct reduction shaft

3 reducing gas

4 compaction device

5 sieve

6 mixing device

7 Unterkörniges material 7 (which at the

Compaction device 4 downstream HBI screening device 8 is obtained)

8 HBI screening device

9 residues from a steel mill

10 dedusting device

1 1 of water

12 binder (bentonite)

13 kneading device

14 pressing device

15 storage place

16 smelting reduction unit

17 Liquid pig iron

18 topgas

19 mud

20 oxygen

Claims

claims

Anspruch [en] A process for producing iron oxide-containing compacts from lower-grained oxidic iron carriers by preparing a mixture comprising the lower-grained oxidic iron carriers, bentonite as binder and water, pressing the mixture, and hardening the green compacts obtained during the pressing, characterized in that the mixture after combining their components, at least 3 minutes, preferably at least 5 minutes, up to 30 minutes, preferably up to 20 minutes, particularly preferably up to 15 minutes

Kneading is subjected, followed by the pressing.

2. The method according to claim 1, characterized in that the mixture comprises 3 to 12% by weight of bentonite, based on the amount of the lower-grained oxidic iron carrier.

3. The method according to claim 1 or 2, characterized in that the mixture and iron-containing metallurgical residues,

preferably at least one member of the group

metallized Fe-Fines,

- tinder,

- hut dusts,

- sludge,

Material derived from a steelmaking process which involves the production of pellets made according to the invention

Iron sponge and / or recovered pig iron is used,

includes.

4. The method according to any one of claims 1 to 3, characterized in that the mixture also comprises finely particulate hematitic and / or limonitic material.

5. The method according to any one of claims 1 to 4, characterized in that the mixture also in the dedusting of top gas, reducing gas, or of

Generator gas comprises a plant for the reduction of oxidic iron carriers by means of a reducing gas resulting fine particulate material.

6. The method according to any one of claims 1 to 5, characterized in that there is a heating of the mixture during the kneading process.

7. compact, obtainable by a method according to one of claims 1 to 6.

8. Use of a compact according to claim 7 as a lumpy oxidic iron carrier for the production of sponge iron or liquid pig iron.