MXPA97004230A - Procedure for the direct reduction of granular material containing iron oxide through a fluidized bed process, and provision to parallel the procedimie - Google Patents

Abstract

The present invention discloses a fluidized bed process for directly reducing a granular material containing iron oxide, the iron oxide-containing material is first reduced in at least one preliminary reduction platform (7) by reducing gas and subsequently reduced to sponge of iron in a final reduction platform (8). The reduction gas is constituted, in part, by recently supplied reduction gas and by the blast furnace gas produced during the reduction of the iron-containing material, and is introduced into the final reduction platform (8) where it reacts, is extracted , and part of it is introduced in at least one preliminary reduction stage (7) where it reacts, is extracted, is purified and is finally used as blast furnace gas, the rest is divided, purified, the CO2 removed and the gas heated then and used as a reduction gas. To ensure that the reaction proceeds without the fluidized bed "clogging", minimizing the amounts of hydrocarbon carriers used to generate the reduction gas, new reduction gas is produced from synthesis, and all of the reduction gas that is feed to the final reduction platform (8) is chemically conditioned on an individual conditioning platform (19; 15), the CO2 is removed and the gas is subsequently heated

Description

"PREDICTING FOR DIRECT DRIVING DF MATERIAI FINANCIAl? MF MisiTiFiMP nxmn DF HIFRR? MFGHANTF I IM PRnrp? N DF LF? HO FHJini7ADQ. AND ISPOSITION FOR CARRYING OUT THE FACE OF THE PRQCFDIMIENTQ" DESCRIPTION OF THE INVENTION The present invention relates to a process for the direct reduction of granular material containing iron oxide by a fluidized bed process, the iron oxide-containing material being reduced previously with the cooperation of a reducing gas in at least one step of prereduction and then reduced to spongy iron in a final reduction stage, the reducing gas being partially produced from fresh supplied reducing gas, and from overhead gas which takes place during the direct reduction of the iron-containing material, this being fed to the final reduction stage, reacting therein, extracted, and a portion then supplied to at least one prereduction stage, in which it reacts, is extracted from it and subjected to a wash and then discharged as overhead gas, while the other portion is derived, washed, purified of C02, heated and subsequently used e similarly as reducing gas; as well as a provision to carry out the procedure. A method for the direct reduction of iron ore is known from US-A-5,082,251. In order to use the reducing potential REF: 24832 and the thermal energy of the reducing gas as much as possible, the reducing gas is conducted through all the stages of reduction, withdrawn as overhead gas from the reduction stage provided in first place seen in the direction of flow of the material containing iron oxide and being finally washed. A portion of the overhead gas is compressed, heated and subsequently supplied to the reduction process as a recycled reducing gas, whereby an advantage of the reductants still available in the overhead gas can be achieved. In this case, however, it is disadvantageous that all the fluidized bed reduction stages must be dimensioned in such a way that they are capable of operating with the total amount of gas, ie the newly produced reducing gas plus the recycled reducing gas. In the reduction of iron oxides by a fluidized bed process using CO / C02 mixtures, acicular iron precipitations at higher temperatures (for example greater than 700 ° C) occur at the surface of the fine particles of mineral and with a reduced reduction potential (for example in the case of contents of C02 and H20 increased in the reducing gas). These precipitations of iron are the origin of the phenomenon of "adhesion" (sticking) in the fluidized beds. In the case of very high degrees of reduction, an agglomeration of the mineral takes place, the reduction process being impeded.

Even when the reduction is developed to a reduction potential very high or higher than the reducing gas, the iron precipitations will be dense or porous, not observing the phenomenon of "adhesion" (sticking). A process of the type initially described is known from German patent DE-C 1,163,353. In this case the iron ore is reduced to metallic iron in a primary stage and in a secondary stage, being the gases of exit (head gas) coming from the primary stage regenerated and recycled to the circulation system. The regeneration is carried out by removing the oxidation products H20 and / or C02, which cause an increase in the concentration of the substances that have an inert behavior with respect to the reduction process, for example nitrogen. For this purpose a portion of the regenerated gas it is withdrawn in order to limit the increase in the level of inert substances. Exit gas that escapes from the secondary stage still has enough reduction potential to be used in the primary stage, to which it is fed. According to the German patent DE-C-1,163,353, the velocities of the exhaust gases from the two stages are adjusted to each other so that 4 to 30% of the exhaust gases escaping from the secondary stage are derived between the secondary stage and the primary stage, being recycled through the circulation system to the secondary stage. The aforementioned is carried out with the purpose of reducing the exhaust gas velocity of the exhaust gases coming from the primary stage, so that this exit gas velocity corresponds to the exit gas velocity of the gases escaping the exhaust gas. secondary stage. With this measure the overall performance is increased and the volume of entrained dust is reduced. A disadvantage in this case is that both the fresh reducing gas supplied to the system in order to replace the enriched exhaust gas that has been withdrawn, as well as the overhead gas and also the reducing gas extracted between the primary stage and the secondary stage. , they must be subjected to a chemical preparation independently of each other. The volume of gas to be regenerated is substantial, since the exit gas that must be evacuated from the system and that includes an increased portion of inert components is only derived after regeneration. Furthermore, the costs associated with at least two regenerators according to the prior art for two gas streams or a common regenerator for these two gas streams coming from the reduction stages and one gas treatment plant for the gas Cool reducer are considerable and difficult to control. The adjustment of a specific chemical composition of the reducing gas causes considerable expense.

The purpose of the present invention is to avoid said disadvantages and difficulties and its purpose is to provide a method and an arrangement for carrying out the procedure that ensures the reduction without the occurrence of the phenomenon of "adhesion" (sticking), through an increase of the reduction potential of the reducing gas, however, not increasing the amount of hydrocarbon carriers used to produce the reducing gas, i.e. in other words, the amount of gas to be reformed must not be increased; on the contrary, it is desired to achieve a saving of hydrocarbon carriers compared to the prior art. In particular, the present invention has the purpose of enabling the control and / or simple adjustment of the chemical composition of the reducing gas, keeping the investment costs as low as possible for the means for adjusting the chemical composition of the reducing gas, said means having to be also operable as economically as possible. According to the present invention this object is achieved by the fact that the reducing gas is produced from synthesis gas, such as reformed natural gas and all of the reducing gas supplied to the final stage of reduction released from C02 and conditioned with respect to its chemical composition in a single stage of preparation of gas to be finally heated. The conditioning of the chemical composition of the fresh reducing gas, overhead gas, as well as the reducing reducing gas after the final stage of reduction, is carried out in the gas preparation stage through the following operating steps: The elimination of C02 is carried out by means of known physical and chemical processes. The adjustment of the CO / H2 ratio is carried out by means of a water gas conversion according to the water-gas reaction CO + H20 «- * C02 + H2.If you see the technical side, the procedure starts with a conversion of water gas adapted to the thermodynamic conditions of the desired CO / H2 ratio in a water gas reactor. For the conversion of CO to H2 steam is used, the excess steam being condensed after the conversion. The resulting C02 is removed by a C02 wash operation arranged downstream. The H2S is also usually removed at the same time with the C02 wash. The adjustment of the content of H20 can be carried out in a separate step of the process, moistening the gas (condenser, spray chiller). The latter has to be disposed downstream with respect to the washing operation, since usually a low water content is adjusted during the washing operation of C02. By combining water gas conversion with C02 washing and gas moistening, it is possible to adjust the content ratio of C0 / H2 and C02 and a reducing gas. An additional option to make such an adjustment could be achieved through a bypass of the conditioned gas, being possible to influence the content of H2S and also, within a certain range, on the levels of the main components H2, H20 , CO and C02.

By the way, with the method according to the present invention, the exploitation of the reduction potential still present in the reducing gas that leaves the final reduction stage and that is derived from it for other reduction stages and / or some preheating step that can be provided, resulting precisely from this fact the essential advantages: According to the present invention a high reduction potential is assured by increasing the amount of reducing gas, having been foreseen for the reduction process that is carried out in stages a Increased amount of reducing gas only in the final reduction stage. This measure reliably avoids "adhesion" in the final reduction stage in which the temperature is the highest and the danger of "adhesion" greater, simultaneously obviating the need to dimension all the parts of the installation, that is to say all the gas conduits, reactors, compressors, etc., and preheating stages and fluidized bed reducing stages that can be provided, in such a way that the they can be operated with the increased amount of reducing gas. Consequently, the present invention makes possible the selective use of a high reduction potential and consequently other reduction stages can be provided with the theoretically minimum amount of reducing gas, so that they can be proportionally reduced in size and more economically. As a result, it is not only possible to dimension all parts of the installation optimally, namely in the smallest possible way and with the maximum possible production capacity, but with this procedure it also becomes feasible to operate the arrangement with the least amount possible of hydrocarbon carriers required to produce the reducing gas; in other words, the consumption of gas to be reformed, such as natural gas, can be minimized, while simultaneously avoiding any danger of "adhesion" (sticking). Another advantage of the process according to the present invention is distinguished in that only a small amount of compression work is required, since the inlet pressure for a compression that is provided after the single stage of preparation of Gas is determined by the low pressure level of the overhead gas.

Since a very high reduction potential is available for the last reduction stage, the reducing gas that has been taken from the final reduction stage, derivative and recycled thereto, can be heated to a reduction temperature comprised in the range from 800 to 900 ° C, for example at a temperature of approximately 850 ° C. The overhead gas and reducing gas that has been derived from the final reduction stage, as well as the reformed natural gas, are released from C02 in a C02 elimination plant. To adjust an optimal chemical composition of the reducing gas, a portion of the overhead gas and / or a portion of the reducing reducing gas are recycled in the unpurified state of C02, the recycled gas being in the doped state of C02, preferably mixed with the reducing gas fed to the gas. the final reduction stage before the latter is heated.

According to a preferred embodiment, the reducing gas taken and derived from the final reduction stage is subjected to a heating and a removal of C02 for which it is subjected to a reforming operation together with the gas to be reformed and which serves to produce the reducing gas, and the overhead gas. In order to avoid enrichment with inert gases (N2), a portion of the overhead gas is extracted from the recirculation system, namely after the compression of the head gas and before the head gas is fed to the head gas. the gas preparation stage, the portion of gas extracted from the overhead gas used to heat the reducing gas, preferably by combustion, for optimum use of energy. One possibility to adjust the temperature in the fluidized bed reduction zones is given by the fact that the prereduction stage is preceded by at least one preheating step for the iron oxide-containing material and the converted reducing gas leaving the The pre-reduction step is used for preheating the iron oxide-containing material, preferably after deriving a portion of the converted reducing gas. An arrangement for carrying out the inventive process, comprising: at least two fluidized bed reactors successively connected in series, in which the iron oxide-containing material is conducted from a fluidized-bed reactor to a fluidized-bed reactor in one direction through conveyor ducts and the reducing gas is conducted from fluidized bed reactor to fluidized bed reactor in the opposite direction through connecting ducts for reducing gas; a head gas discharge duct discharging to the reacted reducing gas from the first fluidized bed reactor, a bypass duct which is derived from the connecting conduit for reducing gas which connects to the fluidized bed reactor arranged at the end in the direction of flow of the material containing iron oxide with the fluidized bed reactor that precedes it; a gas preparation means for preparing the overhead gas and the derivative reducing gas through the bypass line, as well as a gas supply means for the newly supplied reducing gas; and a gas heater from which there emerges a reducing gas supply conduit leading the heated reducing gas to the ultimately arranged fluidized bed reactor, characterized in that the fluidized bed reactor arranged in the last term in the flow direction of the The iron oxide-containing mineral is preceded by a single gas preparation medium for chemically conditioning fresh reducing gas, overhead gas and derivative reducing gas, as well as the gas heater. A preferred embodiment is characterized in that it comprises a gas reformer from which a gas conveyor conduit for transporting fresh reducing gas, which is connected through a conduit with the overhead gas discharge conduit and with the branch conduit, exits. which discharges the reducing reducing gas, and because seen in the direction of the gas stream, a single gas disposal arrangement and a gas heater-disposed after the last one-have been provided in a position that is located after the connection point. Another preferred embodiment is characterized in that the gas preparation means is constituted by a gas reformer from which the reducing gas feed line exits. The gas preparation means can preferably be bridged by means of a bypass for overhead gas and / or bypass reducing gas. From the head gas discharge conduit (12) a branch conduit that flows into the gas heater preferably exits. The present invention will now be described in more detail with reference to two exemplary embodiments illustrated in the accompanying drawings, each one of Figures 1 and 2 illustrating an advantageous variant of the method according to the present invention in the form of a blocks diagram . The arrangement according to the present invention is provided with three fluidized bed reactors 1 to 3 successively connected in series, the iron oxide-containing material, such as fine mineral being, being fed through a mineral charging conduit 4 to the first fluidized bed reactor 1 in which a preheating of the fine mineral takes place in a preheating step 5 and optionally a prereduction, said material being followed by a fluidized-bed reactor 1 to a fluidized-bed reactor 2, 3 through conveyor ducts 6. The prereduction is carried out in the fluidized bed reactor 2 in a prereduction stage 7, while the final reduction of the fine ore to spongy iron takes place in the fluidized bed reactor 3 in a final reduction stage. 8. The completely reduced material, ie sponge iron, is supplied to a briquette making arrangement 10 at ravés of the conveyor duct 9. In countercurrent to the mineral stream, the reducing gas is conducted from the fluidized-bed reactor 3 to the fluidized-bed reactor 2 to 1 through connection ducts 11, being discharged through a discharge duct of head gas 12 of the fluidized bed reactor 1 arranged at the end in the direction of the gas stream as the overhead gas, the same being cooled and washed in a wet scrubbing device 13. The production of reducing gas is carried out by reforming natural gas that is fed through a duct 14 to a reforming device 15, optionally after having desulfurized it in a desulphurisation plant. The reformed gas produced from natural gas and steam, which is fed through a duct steam 16, consists essentially of H2, CO, CH4, H20 and C02.

This reformed gas is fed through a gas conveyor conduit 17 which opens into the head gas discharge conduit 12, together with the head gas compressed by means of a compressor 18, to a disposal arrangement of C02 19 and then a gas heater 20 and from the latter is supplied through a reducing gas supply conduit 21 to the fluidized bed reactor 3 ultimately disposed in the direction of the fine mineral stream. The elimination arrangement of C02 19 can be constructed by way of example as an absorption arrangement by changing pressure or as a wet chemical or physical C02 scrubber. From the connecting gas connecting conduit 11 connecting the fluidized-bed reactor 3 to the fluidized-bed reactor 2 a branch conduit 22 is derived through which a portion of the reducing gas which reacted in the fluidized-bed reactor is discharged. This branch conduit 22 leads through a scrubber 23 and a compressor 24, opening into the head gas discharge conduit 12, the reducing gas being in turn derived in turn to the purification of CO 2 and a subsequent heating. With this measure it is possible to eliminate to a large extent in a single stage of treatment or preparation stage the C02 of a portion of the reducing gas that reacted in the fluidized bed reactor 3, as well as the reformed gas and the overhead gas, and adjust it to the desired chemical composition, said gases being available (after heating to a reduction temperature of the gas, preferably at a temperature comprised between 800 ° C and 900 ° C) as a reducing gas having a high reduction potential. With this measure a particularly high amount of reducing gas is supplied to the final reduction stage 8, so that despite the relatively high temperature prevailing in the final reduction stage 8 there is no danger of "sticking". due to the large number of available reductants. The heating of the reducing gas portion, discharged through the branch conduit 22, takes place in a regenerative, recuperative form or by a partial combustion of said gas, these heating methods being able to be applied by themselves or in combination with two or three. According to the variant illustrated in Figure 1, the foregoing is carried out by supplying the gas heater 20 with a portion of the overhead gas through a conduit 25, as well as natural gas through a conduit 26, said gases being burned. To the fluidized bed reactor 2, in which the pre-reduction of the fine ore takes place, a much smaller amount of reducing gas is supplied, which additionally has a lower reduction potential, which however is completely sufficient for the pre-reduction. Since at this stage the degree of reduction reached of the material to be reduced is smaller than in the final reduction stage 8, sticking does not take place. Accordingly, this fluidized bed reactor 2 and its supply and discharge conduits 11, etc., can be sized as a function of the reduced amount of reducing gas that is conducted through said fluidized bed reactor 2. The converted reducing gas leaving this fluidized bed reactor 2 is conducted through a conduit 11 to the preheating stage 5, ie the fluidized bed reactor l.If the reducing gas leaving the fluidized bed reactor 2 is not necessary in its entirety for preheating, it is possible to supply a portion thereof through a conduit 27 to a scrubbing device 28 and extract it through a gas discharge conduit 29, optionally being recycled through an illustrated conduit 29 ' with lines of stroke. The elimination arrangement of C02 is preferably bypassed by means of a by-pass line 30 for a certain portion of the reductive gas fed back, bypassing the by-pass line 30 however in the conduit that communicates to the disposal arrangement of C02 19 with the gas heater 20. Through said by-pass conduit 30 it can be mixed consequently the reducing gas recycled with the purified gas of substantially C02, the desired chemical composition of the mixing gas, ie the reducing gas, can be adjusted in a simple manner by a flow control or regulation. To adjust the preheating temperature of the fine ore, a gas containing oxygen, such as air or oxygen, can be supplied to the preheating stage 5, that is to the fluidized bed reactor 1, through a duct 31, whereby a partial combustion or possibly also a total combustion of the converted reducing gases fed to the preheating stage 5. By controlling a partial combustion it is possible to adjust the temperature of the fine ore during heating to optimize the temperatures in the stages Subsequent reducers 7, 8. In the case of a complete combustion, the produced combustion gases are discharged to the environment through a washing device 13 through a conduit 12 'illustrated with dashed lines. To control the combustion inside the fluidized-bed reactor 1, natural gas can be supplied to the conduit 11 (through a natural gas supply conduit 14 'illustrated with dashed lines). According to an embodiment illustrated in Figure 2, of an arrangement according to the present invention, the gas reformer 15 is supplied with both the overhead gas as well as the reducing gas extracted and derived from the final reduction stage 8, namely after having been mixed with the natural gas to be reformed, so that in this case the gas reformer serves as a CO2 removal device and a gas heater for the overhead gas and the derivative reducing gas. The elimination of C02 by means of natural gas is effected in this case according to the following reaction equation: C02 + CH4 = 2 CO + 2 H2 The reaction of H20 contained in the reducing gas also takes place according to the following equation Analogous reaction (steam reforming): H20 + CH4 = CO + 3H2 A portion of the overhead gas is used to supply power to the gas reformer and is fed thereto through a conduit 25 together with natural gas fed through the gas. a conduit 26. The present invention is not limited to the embodiments illustrated in the drawings, it being possible to modify the same in different aspects. By way of example it is possible to select the number of fluidized bed reactors according to the requirements. Example A: In an arrangement corresponding to the drawing according to Figure 1, 100 tons of ore with the composition indicated in Table I are charged to produce 70 tons of sponge iron. By natural gas with the chemical composition indicated in Table II, it is produced in the reformer. of gas 15 a reformed gas whose chemical composition is indicated in Table III. Table I Table II Table III Dry mineral Gas Natural Gas reformed Fe203 94% CH4 94.3% H2 72.0% Fe 66% CmHn 0. 3% H20 1. 5% LOI 1% C02 0. 2% CO 11. 7% N2 5. 2% C02 9. 3%, H2S 10 ppm CH4 4. 0% N2 1. 5% Said reformed gas produced in an amount of 56,000 NmVh is mixed with 65,000 NmVh of head gas fed through the head gas bypass conduit 12 and with 87,500 NmVh of reducing gas extracted from the final reduction stage 9 and derived through the branch conduit 22. This gas mixture has the chemical composition indicated in Table IV, which is subjected to a C02 removal and a subsequent heating. After leaving the gas heater 20, it presents the chemical composition indicated in Table V. Table IV Table. a V H2 63.2% H2 67.7% H20 2.0% H20 0.6% CO 8.0% CO 8.5% co2 5.1% C02 0.1% CH4 14.8% CH «15.9% N2 6.9% N2 7.2% The reducing gas purified from C02 and heated is available in result in an amount of 198,000 NmVh with a temperature of 850 ° C for the final reduction stage 8. Example B: In an arrangement corresponding to the drawing in Figure 2, it is charged to produce 70 t of sponge iron 100 t of ore with the composition indicated in Table VI. A reformer 15 is supplied in total 135,750 NmVh of feed gas with the chemical composition indicated in Table VII, which consists of a mixture of 43,000 NmVh of partially consumed reducing gas from the final reduction stage 8, 73,000 NmVh of head gas fed through line 12 and 13,750 NmVh of natural gas supplied through line 14. Natural gas has the chemical composition indicated in Table VIII.

The amount of reducing gas produced in the reformer 15 and fed to the final reduction stage 8 with the chemical composition indicated in Table IX is 169,000 NmVh. The amount of combustion gas fed to the reformer 15 and constituted by the overhead gas and natural gas is 38,650 NmVh. Table VI Table VII Dry ore Fe203 Feeding gas 94% H, 38.1% Fe 66% H20 11.4% LOi 1% CO 23.3% C02 10.7% CH4 13.2% N, 3.3% Table VIII Table IX Natural Gas Reductors CH4 94.3% H2 52.0% CmHn 0.3% H20 5.2% co2 0.2% co 33.5% N2 5.2% co2 2.3% H2S lOppm CH4 4.0% N2 3.0% It is noted that in relation to this date, The "best" known by the applicant to carry out the said invention is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (16)

1. CLAIMS 1.- Process for the direct reduction of granular material containing iron oxide by means of a fluidized bed process, in which the material containing iron oxide is previously reduced by means of a reducing gas in at least one pre-stage. -reduction and then reduced to spongy iron in a final reduction stage, in which reducing gas is produced partially from fresh supplied reducing gas and overhead gas that takes place during the direct reduction of the iron-containing material, being the same fed to the final reduction stage, reacting therein and withdrawn therefrom, a portion subsequently being fed to at least one pre-reduction step in which it reacts, being extracted from it, subjected to washing and then discharged as overhead gas and the other portion being derived, washed, purified of C02, heated and then used in a similar way as reducing gas, CHARACTERIZED because the fresh reducing gas is formed by synthesis gas, such as reformed natural gas, and the total of the reducing gas supplied to the final reduction stage is purified from C02 and conditioned with respect to its chemical composition in a single stage of gas preparation; and finally heated.
2. 2. Process according to claim 1, characterized in that in the single stage of gas preparation is carried out an adjustment of the ratio CO / H2 of the reducing gas by conversion according to the reaction of water gas.
3. 3. Method according to claim 1 or 2, CHARACTERIZED because in the single stage of gas preparation an adjustment of the H20 content of the reducing gas is carried out, namely in a single preparation step that is carried out after the removal of CO2.
4. 4. Process according to claim 3, characterized in that a reduction of the reducing gas is carried out by means of a condenser or spray cooler.
5. 5. - Process according to claim 1, CHARACTERIZED because with an elimination disposition of C02, the head gas and the reducing gas that has been derived from the final reduction stage are released from C02, as well as the reformed natural gas.
6. 6. Process according to claim 5, characterized in that a portion of the overhead gas and / or a portion of the derivative reducing gas are recycled in an unpurified form of C02.
7. 7. Process according to claim 6, characterized in that the gas recycled in the unpurified state of C02 is mixed with the reducing gas supplied to the final reduction stage before the latter has been heated.
8. 8. Process according to claim 1, characterized in that the reducing gas extracted and derived from the final reduction stages is subjected to a heating and a removal of C02, being subjected to a reforming operation together with the gas to be reformed and which serves to produce the reducing gas, together with the overhead gas.
9. 9. Process according to at least one of claims 1 to 8, characterized in that a portion of the overhead gas is extracted from the recirculation system, namely after. carry out the compression of the head gas and before the overhead gas has been fed to the gas preparation stage.
10. 10. Process according to claim 9, CHARACTERIZED because the extracted portion of overhead gas is used to heat the reducing gas, preferably by combustion.
11. 11. Arrangement for carrying out the process according to any of claims 1 to 10, which comprises: at least two fluidized bed reactors connected mutually in series, in which the material containing iron oxide is conducted to through conveyor conduits of a fluidized-bed reactor to another fluidized-bed reactor, in one direction and the reducing gas is conducted through connecting ducts for reducing gas in the opposite direction of fluidized-bed reactor to fluidized-bed reactor; a head gas discharge duct discharging the reacted reducing gas from the first fluidized bed reactor; a branch conduit that is derived from the connection conduit for reducing gas that connects to the fluidized bed reactor arranged in the last term in the direction of the flow of the iron oxide-containing material with the fluidized-bed reactor arranged in a manner that precedes it; and a gas preparation means for preparing the overhead gas and the derivative reducing gas through the branch line, as well as a gas preparation means for fresh reducing gas supplied and with a gas heater from which a line of gas exits. feed reducing gas which conducts the heated reducing gas to the fluidized bed reactor arranged in the last term, CHARACTERIZED because the fluidized bed reactor arranged in the last term seen in the direction of the current of the iron oxide-containing material is preceded by a only gas preparation medium for chemically conditioning fresh reducing gas, overhead gas and derivative reducing gas, as well as for a gas heater.
12. 12. Arrangement according to claim 11, characterized in that it has a gas reformer from which a gas conveyor conduit that carries fresh reducing gas and which is connected to the head gas discharge conduit and the conduit- branch that discharges the derivative reducing gas, and having seen, in the direction of gas stream, at a point after the connection point a single gas disposal arrangement and a gas heater disposed after the latter.
13. 13. Arrangement according to claim 11, characterized in that the gas preparation arrangement is constituted by a gas reformer from which the reducing gas supply conduit exits.
14. 14.- Provision according to at least one of the claims 11 to 13, CHARACTERIZED because the gas preparation means can be bridged by means of a by-pass for overhead gas and / or derivative reducing gas.
15. 15. Arrangement according to at least one of claims 11 to 14, characterized in that a branch line emerges from said head gas discharge conduit and empties into the gas heater.
16. 16. Process for the production of a marketable product, such as laminates produced from semi-processed pig iron or steel manufactured according to a method according to one of claims 1 to 10.