Title of Invention	"A METHOD FOR PRODUCING HOT BRIQUETTED IRON AND APPARATUS THEREOF"
Abstract	A method for producing hot briquetted iron from charging substances formed from iron ores and fluxes and having, at least partially, a content of fines, characterized in that, after CO2- purification, the export gas emerging from the preheating zone (2) is utilized for the generation of hotbriquetted iron, optionally after admixing a portion of the reducing gas emerging from the reduction zone, (18), wherein fine ore is subjected to preheating in a preheating zone (2), subsequently is subjected to largely a complete reduction in at least one reduction zone (18) and furthermore is supplied to a compressing and briquetting means (48, 49) and, after heating, the export gas is conducted into the at least one reduction zone, under the formation of a fluidized bed (18), and is withdrawn from the same after having passed through the latter and is supplied to the preheating zone (2), under partial combustion, in order to increase the temperature for the formation of a fluidized bed.

Title of Invention

"A METHOD FOR PRODUCING HOT BRIQUETTED IRON AND APPARATUS THEREOF"

Abstract

A method for producing hot briquetted iron from charging substances formed from iron ores and fluxes and having, at least partially, a content of fines, characterized in that, after CO2- purification, the export gas emerging from the preheating zone (2) is utilized for the generation of hotbriquetted iron, optionally after admixing a portion of the reducing gas emerging from the reduction zone, (18), wherein fine ore is subjected to preheating in a preheating zone (2), subsequently is subjected to largely a complete reduction in at least one reduction zone (18) and furthermore is supplied to a compressing and briquetting means (48, 49) and, after heating, the export gas is conducted into the at least one reduction zone, under the formation of a fluidized bed (18), and is withdrawn from the same after having passed through the latter and is supplied to the preheating zone (2), under partial combustion, in order to increase the temperature for the formation of a fluidized bed.

Full Text	The invention relates to a process for producing molten from charging substances formed of iron ores and fluxes and at least partially comprising fines, wherein the charging substances are directly reduced to sponge iron in at least one reduction zone by the whirl layer method, the sponge iron is melted in a melting-gasifying zone under supply of carbon carriers and oxygen-containing gas, and a CO and H2 ontaining reducing gas is produced, which is injected into the reduction zone, is reacted there, is withdrawn as an export gas and is supplied to a consumer, as well as a plant for carrying out the process. A process of this kind is known, for instance, from AT-B 390 622. According to AT-B 390 622, charging substances having largely varying grain sizes are processed, the charging substances being pre-reduced and separated by wind screening into fractions of different grain sizes, which are then completely reduced separately. However, this known one-step process only offers a low thermal utilization of the reducing gas and consequently involves an elevated consumption of reducing gas. Nor is the optimum utilization of the energy chemically bound in the reducing gas feasible. The invention has as its object to provide a process of the initially defined kind as well as a plant for carrying out the process., which enable the use of iron ores and fluxes comprising at least a share of fines, in an economic manner by using untreated coal as a carbon carrier, wherein the chemically bound energy (CO, H2-content) still contained in the reducing gas used can be utilized. In accordance with the invention, this object is achieved with a process of the initially defined kind in that - primarily hematite and/or magnetite fine ores and/or ore dusts are subjected to preheating by the whirl layer method in a preheating zone, - the thus preheated charging substances are completely reduced to a major extent in at least one consecutively arranged reduction zone, - whereupon at least the more finely participate charging substances are charged into the fluidized bed and/or, if desired, also into the fixed bed, of the melting-gasifying zone by forced conveyance, preferably by pneumatic conveyance, and are melted there. ^--Accoiding to AT-B 387 403, siderite-containing and/or hydrated charging substances are calcined in a fixed-bed heating zone preceding the fixed-bed direct reduction zone, wherein, however, only coarse lumps of iron-ore-containing charging substances capable of being processed merely in the fixed bed are used for charging. It is essential to the invention that the charging substances are processed not in the material counterflow as is the case with the known fixed-bed methods (AT-B 387 403), but in stable or circulating whirl layers, i.e., for instance, in diagonal flow, thus enabling the economic processing of fine ores and ore dusts on account of the improved energetic gas utilization. This is of importance, because, at present, about 75 % of the world's ores incurs as fine ore, which is cheaper than lumpy ore or agglomerates. According to the invention, not only reduction is effected by the whirl layer method, but also preheating. By the multi-step whirl layer method according to the invention it has become possible to use the reducing gas in an optimum manner without having to feed additional energy. From US-A 5,082,251, a direct reduction process is known, according to which fine ores rich in iron are reduced after complex ore preparation, such as drying, screening and breaking, in a system of whirl layer reactors in cascade arrangements by aid of reformed natural gas or oil so as to obtain a very narrow grain size distribution. Subsequently, the iron powder is hot- or cold-briquetted. Smoke gas is used as the fludizing gas in the preheating stage, which is produced by burning air and natural gas; thus, external energy must be introduced, only the sensible heat of the whirling gases being utilizable. In contrast, reduction according to the process of the invention is effected by means of solid carbon carriers,, such as coal, and hence, according to the invention, CO reduction is preponderant, whereas, according to US-A-5,082,251, the direct reduction of ore primarily is effected by H2- A substantial advantage of the process according to the invention is to be seen in that ore preheating is effected by means of process reducing gas from the final reduction stage and not by external gas supply as according to US-A-5,082,251, which, of course, involves accordingly high costs. Another advantage of the gas control implied by the invention resides in that pre-reduction can be achieved by the reducing atmosphere in addition to preheating, a particularly efficient utilization of the reducing gases, thus, being ensured. To cool the reducing gas formed in the melting-gasifying zone, the reducing gas, according to the invention, partially is fed directly to the reduction zone for forming a whirl layer and partially, after purification in a hot cyclone an in a scrubber, is admixed as a cooling gas to the first portion of the reducing gas fed to the reducion zone. To control the state of fluidization of the charging substances in the reducing zone, a portion of the reducing gas advantageously is fed to the reduction zone in the region of the whirl layer and part of the portion of the reducing gas supplied to the hot cyclone is fed to the reduction zone into a fluidized bed formed in the lower part therof. To efficiently preheat the charging substances, the reducing gas leaving the reduction zone advantageously is fed to the preheating zone, a temperature increase being effected by the partial combustion of the reducing gas. To efficiently use the dust and fines incurring in reduction, the reducing gas withdrawn from the reduction zone advantagously is freed from fines in a reduction cyclone and the fines separated in the reduction cyclone are completely reduced to a major extent during separation and are supplied by means of an injector to the melting-gasifying zone in the region of feeding of oxygen-containing gas. Fines that have been completely reduced in the reduction zone already prematurely, suitably are partially discharged from the whirl layer of the reduction zone and are supplied by means of an injector to the melting-gasifying zone in the region of feeding of oxygen-containing gas via a sleuce system, the portion of charging substances discharged from the whirl layer of the reduction zone suitably being supplied to the me king-gasifying zone together with the material separated in the reduction cyclone. In doing so, the dust separated in the hot cyclone advantageously is supplied to the melting-gasifying zone in the region between a fine-coke fluidized bed forming there and a coarse-coke fluidized bed, via a sleuce system by aid of an injector and by means of an oxygen dust burner. Suitably, the addition of fluxes is effected by charging a portion of the fluxes required for the melting process, together with the coal, directly into the melting-gasifying zone and a portion of the fluxes, together with the fine ore, into the preheating zone, wherein, advantageously, the fluxes charged together with the coal are introduced as coarse grains, preferably ranging between 4 mm and 12.7 mm, and the fluxes charged together with the fine ore are introduced in a fine-grain form, preferably ranging between 2 mm and 6.3 mm. Particularly efficient reduction may be obtained by providing two locally separated consecutively arranged reduction zones, the reducing gas leaving the first reduction zone being conducted to the second reduction zone preceding the first reduction zone in the sense of the fine ore flow and from there being fed to the preheating zone under compression. To utilize the excess gas incurring in the process, the export gas leaving the preheating zone, according to a preferred embodiment, if desired, upon admixture of a portion of the reducing gas leaving the reduction zone, after CC>2 purification, is used for producing hot-briquetted iron, wherein fine ore is subjected to preheating in a preheating zone, subsequently is subjected to a largely complete reduction in at least one reduction zone and, furthermore, is supplied to a compressing and briquetting means, and the export gas, upon heating, is conducted into the at least one reduction zone under formation of a whirl bed, and, after having flown therethrough, is withdrawn from the same and is fed to the preheating zone under partial combustion with a view to temperature elevation for the purpose of forming a whirl bed. An arrangement for carrying out the process according to the invention, comprising at least one reduction reactor, into which a conveying duct for charging substances containing iron ore and fluxes, a gas duct for a reducing gas as well as a conveying duct for the reduction product formed therein and a gas duct for the export gas enter, and comprising a melter gasifier, into which the conveying duct conducting the reduction product from the reduction reactor enters and which comprises feed ducts for oxygen-containing gases and carbon carriers as well as taps for pig iron or steel pre-material and slag, wherein the gas duct for reducing gas formed in the melter gasifier entering the reduction reactor depajts from the melter gasifier, is characterized in that the reduction reactor is designed as a whirl-layer reduction reactor and that, in the flow direction of the charging substances, a whirl-layer preheating reactor precedes the whirl-layer reduction reactor, the gas duct of the whirl-layer reduction reactor entering into the whirl-layer preheating reactor, and that a pneumatic conveying duct is provided for conveying the sponge iron formed in the whirl-layer reduction reactor into the melter gasifier, the conveying duct entering the melter gasifier on the level of the fluidized bed and/or fixed bed. The reduction process may be controlled via the degree of fluidization prevailing within the reduction reactor (and also within the preheating reactor) advantageously in that the whirl-layer reduction reactor comprises a lower part having a smaller diameter and an upper part following upon the lower part and having a larger diameter, the transition from the lower part to the upper part being conically designed and the gas duct for the reducing gas entering the conical transition piece, wherein the whirl-layer preheating reactor suitably has a conical lower end into which the gas duct for the reducing gas runs. In order to be able to discharge completely reduced fines from the whirl-layer reduction reactor, the whirl-layer reduction reactor, on the level of the whirl layer, is provided with a fines discharge means, from which a conveying means leads to a pneumatic conveying means entering into the melter gasifier on the level of the fixed bed or fluidized bed formed therein. According to a preferred embodiment, two whirl-layer reduction reactors are consecutively provided in the flow direction of the charging substances. A particularly efficient utilization of the excess gases forming is provided if the gas duct for the export gas, after the intermediate arrangement of a CO2 scrubber and a heating means, runs into at least one reduction reactor for producing hot-briquetted iron, from which reduction reactor a gas duct is conducted into a whirl-layer preheating reactor, wherein a fine-ore charging duct enters into the whirl-layer preheating reactor and a conveying duct departs from the whirl-layer preheating reactor, conducting the preheated fine ore to the reduction reactor, and if a compressing and briquetting means is arranged to follow the reduction reactor in the direction of the fine-ore flow. In the following, the invention will be explained in more detail by way of three exemplary embodiments schematically illustrated in the drawing, wherein Figs. 1 to 3 each depict an advantageous embodiment of a plant according to the invention in schematic illustration. By 1 a preheating reactor is denoted, which is designed as a whirl-layer preheating reactor and into which charging substances containing iron ore and fluxes are chargeable via a. charging duct 3 entering laterally on the level of the whirl-bed zone 2 (preheating zone). On the upper end of the shaft-likely designed whirl-layer preheating reactor 1, the gases formed therein and flowing therethrough are withdrawn via a gas discharge duct 6 equipped with a gas purifying cyclone 4 and a gas scrubber 5, such as a Venturi scrubber. These gases are available as hiqh-quality export gases having a calorific value of about 8000 kJ/Nm3 for various purposes, e.g., for the production of current with or without oxygen. All of the charging substances preheated in the whirl-layer preheating reactor 1, via a conveying duct 7, reach a reduction reactor 8 also designed as a whirl-layer reactor and are completely reduced to a major extent in the same. Via a pneumatic sponge-iron conveying duct 9 (including an N2 injector) - any other forced conveyance could be provided instead - the sponge iron formed in the whirl-layer reduction reactor 8 gets into a rnelter gasifier 10 by being introduced into the same on the level of a fluidized bed III, n provided in the melter gasifier and/or on the level of a fixed bed I located therebelow. The melter gasifier comprises at least one supply duct 11 for coal and fluxes as well as tuyere feeds 12 for oxygen-containing gases arranged on several levels. Molten pig iron 13 and liquid slag 14 collect in the melter gasifier 10 below the melting-gasifying zone formed by a fixed bed I, a coarse coke fluidized bed II located thereabove, a fine coke fluidized bed in located above the latter and a killing pace IV located on top, the pig iron and the slag being tapped separately via a tapping means 15, 16 each. In the melter gasifier 10, a reducing gas is produced from the carbon carriers and from the oxygen-containing gas, which reducing gas collects in the killing space IV above the fluidized bed III and is fed to the whirl-layer reduction reactor 8 through a gas duct 17, via a frustoconical constriction of the substantially shaft-shaped whirl-layer reduction reactor 8, constituting a gas distributing bottom 9 and provided for the purpose of forming a whirl layer 18 or a whirl bed 18 (reduction zone), the reducing gas being supplied via the periphery of the constriction by means of an annular duct 20. The large solids particles, which cannot be kept floating in the whirl layer, centrally descend due to the effect of gravity and are withdrawn through a central solids discharge 21. This central solids discharge 21 is configured such that, via a radial gas feed means 22, a fixed-bed flow is formed into the cylindrical vessel part 23 having a conical bottom 24 and arranged below the frustoconical gas distributing bottom 19 such that the reduction even of large particles can be achieved to a satisfactory extent. Due to the frustoconical shape of the gas distributing bottom 19, the clear tube velocity changes with the height As a result, a special grain size distribution adjusts over the height of the gas distributing bottom 19. By appropriately arranging the tuyeres in the gas distributing bottom 19, an internally circulating whirl layer can, thus, be formed, where the gas velocity is higher in the center than on the periphery. The formation of a whirl layer of this type may be used both for the reduction reactor 8 and for the preheating reactor 1. A portion of the reducing gas leaving the melter gasifier 10 is subjected to purification in a hot cyclone 25, to cooling in a consecutively arranged scrubber 26, and, via a compressor 27, is again admixed to the reducing gas leaving the melter gasifier 10 via a gas duct 28. The dust separated in the hot cyclone 25 is returned into the melter gasifier 10 via an N2 injector 29. A portion of the still uncooled reducing gas leaving the hot cyclone 25 reaches the whirl-layer reduction reactor 8 through its cylindrical vessel part 23 via the gas feed means 22 formed by an annular duct The gas withdrawn from the whirl-layer reduction reactor 8, via a gas duct 30, is fed to a reduction cyclone 31, in which fines still contained in the reducing gas are separated and reduced completely. These fines are introduced into the melter gasifier 10 approximately on the level of the upper end of the fixed bed I via a conveying duct 32 and an N2 injector 33. The partially oxidized reducing gas emerging from the reduction cyclone 8, via the gas duct 30, gets into the whirl-layer preheating reactor 1, wherein, however, part of the same is burnt for heating the reducing gas in a combustion chamber 34, into which a duct 35 feeding an oxygen-containing gas enters. From the whirl-layer reduction reactor 8, a portion of the completely reduced charging substances is withdrawn on the level of the whirl bed 18 by means of a worm conveyor 36 and, preferably together with the fines coming from the reduction cyclone 31, is introduced into the melter gasifier 10 approximately on the level of the upper end of the fixed bed I by means of a conveying duct 37 via an N2 injector 33. The finely paxticulate material separated in the cyclone 4 of the export gas discharge duct 6 is charged via a conveying duct 38 including sleuces 39 - which are also provided in the other conveying ducts 32, 37 for the partially or completely reduced material-through the annular duct 20 feeding the reducing gas into the whirl-layer reduction reactor 8 Accordingly the present invention relates to a method for producing hot briquetted iron from charging substances formed from iron ores and fluxes and having, at least partially, a content of fines, wherein the charging substances are subjected to preheating according to the fluidized-bed method in a preheating zone (2), are directly and to a large extent completely reduced to sponge iron in at least one reduction zone (18, 18") according to the fluidized-bed method, the sponge iron is charged into a melt-down gasification zone (I to IV), is melted undersupply of carbon carriers and an oxygen containing gas, and a CO- and H2-containing reducing gas is generated, which is supplied to the reduction zone (18, 18'), is reacted there, is withdrawn as an export gas and is supplied to a consumer, characterized in that, after CO2- purification, the export gas emerging from the preheating zone (2) is utilized for the generation of hotbriquetted iron, optionally after admixing a portion of the reducing gas emerging from the reduction zone (18), wherein fine ore is subjected to preheating in a preheating zone (2), subsequently is subjected to largely a complete reduction in at least one reduction zone (18) and furthermore is supplied to a compressing and briquetting means (48, 49) and, after heating, the export gas is conducted into the at least one reduction zone, under the formation of a fluidized bed (18), and is withdrawn from the same after having passed through the latter and is supplied to the preheating zone (2), under partial combustion, in order to increase the temperature for the formation of a fluidized bed. Accordingly the present invention also relates to an apparatus for carrying out the process as claimed in claim 1, comprising at least one fluidized-bed reduction reactor (8, 8'), into which a conveyor duct (7) for charging substances containing iron ore and fluxes, a gas duct (17) for a reducing gas as well as a conveyor duct (9) for the reduction product formed therein and a gas duct (30) for the topgas run, and a melter gasifier (10), into which the conveyor duct (9) carrying the reduction product from the reduction reactor (8, 8') runs and which exhibits feed ducts (11, 12) for oxygen-containing gases and carbon carriers as well as taps (15, 16)for pig iron (13) or a steel prematerial and slag (14), respectively, wherein the gas duct for reducing gas formed in the melter gasifier (10), which gas. duct runs into the reduction reactor (8, 8'), originates from the melter gasifier (10), and a fluidized-bed preheating reactor (1) is arranged to precede the fluidized-bed reduction reactor (8, 81) in the flow direction of the charging substances, into which fluidized-bed preheating reactor the gas duct (30) of the reduction reactor (8, 8') runs, and wherein consumed or partially consumed reducing gas may be supplied as an export gas to a consumer via a gas-discharge duct (6, 42), characterized in that the gas duct (6, 42) for the export gas, after the interposition of a CCb-scrubber (45) and a heating means (46), runs into at least one further reduction reactor (8) in order to produce hot-briquetted iron, wherefrom a gas duct is conducted to a fluidized-bed preheating reactor (1), with an ore-dust charging duct (3) running into the fluidized-bed preheating reactor (1) and a conveyor duct carrying the preheated ore dust to the reduction reactor originating from the fluidized-bed preheating reactor (1), and that a compressing and briquetting means (48, 49) is arranged to follow the reduction reactor (8) in the flow direction of the ore dust. The plant according to Fig 1, in detail, functions as follows: The fine ore treated - sieved and dried - and having a grain size distribution of, for instance, - 0.044 mm = approx. 20 % 0.044 - 6.3 mm = approx. 70 % 6.3 -12.7 mm = approx. 10% and a moisture content of approximately 2 % is charged into the preheating reactor 1 pneumatically or by aid of a steep belt or vertical conveyor. There, it is prehated to a temperature of about 850°C in the whirl-bed zone 2 and optionally is pre-reduced on account of the reducing atmosphere to about the wuestite stage. For this pre-reduction procedure, the reducing gas is to contain at least 25 % CO + H2 in order to have sufficient reducing power. Subsequently, the preheated and optionally pre-reduced fine ore flows into the reduction reactor 8 - preferably due to gravity -, in the whirl layer or whirl bed 18 of which the fine ore is largely reduced to the Fe stage at a temperature of about 850° C. For this reduction procedure, the gas is to have a content of CO + H2 of at least 68 %. In the reduction reactor 8, screening of the fine ore takes place, the portion of below 0.2 mm being entrained by the reducing gas into the reduction cyclone 31. There, the complete reduction of the fine ore of below/ 0.2 mm occurs during the separation of the solids by the cyclone effect The finer solids portion discharged from the whirl layer 18 of the reduction reactor 8 by aid of the discharge worm 36 is supplied to the melter gasifier 10 in the region of the blow-in planes of the oxygen-containing gases via sleuces 39, together with the fine ore separated in the reduction cyclone 31, by aid of the N2 injector 33. The coarser solids portion from the lower region of the reduction reactor 8 is blown or charged into the melter gasifier 10 in the region of the fine-coke fluidized bed III via sleuces 39 and by aid of the N2 injector 9 or by means of gravity discharge. The dust separated in the hot cyclone 25 (primarily containing Fe and C) is fed to the melter gasifier 10 in the region between the fine-coke fluidized bed HI and the coarse-coke fluidized bed n via sleuces 39 by aid of the N2 injector 29 and by means of an oxygen dust burner. For the purpose of preheating and calcining, the fluxes required for the process are charged as coarse grains, preferably having grain sizes ranging between 4 and 12.7 mm, via the coal path (11) and as fine grains, preferably having grain sizes ranging between 2 and 6.3 mm, via the fine-ore path (3). For fine ores requiring longer reduction times, a second (as well as, if required, a third) whirl-layer reduction reactor 8' including an additional reduction cyclone 31' is provided in series or in succession to the first reduction reactor 8, as is illustrated in Fig. 2. The fine ore is reduced to the wuestite stage in the second reduction reactor 8' and to the Fe stage in the first reduction reactor 8. In this case, the solids portion discharged from the whirl layer 18' of the second reduction reactor by aid of the discharge worm 36' is charged into the first reduction reactor 8 by gravity, together with the coarser solids portion from the lower region of the second reduction reactor 8'. The fine ore separated in the second reduction cyclone 31' is supplied to the melter gasifier 10 in the region of the blow-in planes of the oxygen-containing gases by aid of the N2 injector 33, together with the fine ore separated in the first reduction cyclone 31. If, when using two whirl-layer reduction reactors 8, 8' and two reduction cyclones 31,31', the operational pressure does not suffice to balance out pressure losses in the system, the gas mixture required for the preheating reactor 1, according to the invention, is brought to the necessary pressure by aid of a compressor 40. In this case, the gas from the second reduction cyclone 31' is cleaned in a scrubber 41. However, in the following, only a partial stream of the gas is compressed - a portion being withdrawn through duct 42 as export gas - and is appropriately mixed with an oxygen-containing gas fed through duct 44 in a mixing chamber 43 such that a partial combustion of the reducing gas subsequently can occur in the preheating reactor 1 for the purpose of attaining the fine-ore preheating temperature required. The high-quality export gas from the pig iron production may be used for the production of current with or without oxygen, as indicated above. According to a preferred embodiment of the invention, which is represented in Fig. 3, the export gas, after CO2 scrubbing 45 and preheating 46 to about 850°C, is re-used as a reducing gas, in the following manner: To produce hot-briquetted iron, fine ore of the same specification as used for the production of pig iron is preheated and reduced by the reducing gas in the same aggregates as used in pig iron production . The completely reduced grain fractions from the at least one reduction reactor 8 and from the reduction cyclone 31 are blown into a charging bunker 47 by aid of N2 injectors 33. Alternatively, the coarser grain fraction can be charged from the lower region of the reduction reactor 8 into the charging bunker 47 by a gravity discharge. After this, the completely reduced fine ore having a degree of metallization of about 92 % and a temperature of at least 750°C reaches a roll briquetting press 49 due to gravity via a pre-compressing worm 48 including a controllable motor. In the following examples, typical characteristic data of the process according to the invention obtained in operating the plants according to the embodiments represented in Figs. 1 to 3 are summarized. Example: Coal analysis (dry analysis values) C 77 % H 4.5 % N 1.8 % O 7.6 % S 0.5 % ashes 9.1 % eg* 61.5% Ore analysis (moist analysis values) Fe 62.84 % Fe2O3 87.7 % CaO 0.73 % MgO 0.44 % SiO2 6.53 % A12O3 0.49 % MnO 0.15% losses on ignition 0.08 % moisture 2 % Grain size distribution of fine ore + 10 mm 0 % 10-6 mm 5.8 % 6-2mm 44.0 % 2-0.63 mm 29.6 % 0.63-0.125 mm 13.0 % -0.125mm 7.6 % Fluxes (dry analysis values) CaO 45.2 % MgO 9.3 % SiO2 1.2 % A12O3 0.7 % MnO 0.6 % Fe2O3 2.3 % losses on ignition 39.1 % For the production of 42 tons of pig iron/hour in the plant according to Fig. 1,42 tons of coal/hour are gassed with 29,000 Nm3O2/hour. The ore consumption therefor amounts to 64 tons/hour and the consumption of fluxes is 14 tons/hour. In addition to iron, the pig iron produced has the following composition: C 4.2 % Si 0.4 % P 0.07 % Mn 0.22 % S 0.04 % The export gas from the pig iron plant incurs at 87,000 Nm^/hour, having the following analysis: CO 36.1 % CO2 26.9 % H2 16.4 % H20 1.5 % N2 + Ar 18.1 % CH4 I % H2S ' 0.02 % Calorific value 6780 kJ/Nm3 When further utilizing the export gas from the pig iron plant for the production of hot-briquetted iron according to Fig. 3, 29 tons of hot-briquetted iron/hour can be produced. The amount of recycled gas required therefor is 36,000 Nm3/hour. The hot-briquetted sponge iron has the following analysis values: Metallization 92 % C 1 % S 0.01 % P 0.03 % The amount of export gas from the plant for the production of hot-briquetted iron is 79,000 Nm3/hour, the gas having the following composition: CO 21.6 % O>2 44.1 % H2 10.6 % H2O 2.8 % N2 + Ar 19.9 % CH4 1 % Calorific value 4200 kJ/Nm3 The necessary electric input of the pig iron plant and of the plant for the production of hot-briquetted iron is 23 MW. The export gas after the plant for the production of hot-briquetted iron corresponds to a thermal output of 145 MW. CLAIM: 1. A method for producing hot briquetted iron from charging substances formed from iron ores and fluxes and having, at least partially, a content of fines, wherein the charging substances are subjected to preheating according to the fluidized-bed method in a preheating zone (2), are directly and to a large extent completely reduced to sponge iron in at least one reduction zone (18, 18') according to the fluidized-bed method, the sponge iron is charged into a melt-down gasification zone (I to IV), is melted undersupply of carbon carriers and an oxygen containing gas, and a CO- and H2-containing reducing gas is generated, which is supplied to the reduction zone (18, 18'), is reacted there, is withdrawn as an export gas and is supplied to a consumer, characterized in that, after COa- purification, the export gas emerging from the preheating zone (2) is utilized for the generation of hotbriquetted iron, optionally after admixing a portion of the reducing gas emerging from the reduction zone (18), wherein fine ore is subjected to preheating in a preheating zone (2), subsequently is subjected to largely a complete reduction in at least one reduction zone (18) and furthermore is supplied to a compressing and briquetting means (48, 49) and, after heating, the export gas is conducted into the at least one reduction zone, under the formation of a fluidized bed (18), and is withdrawn from the same after having passed through the latter and is supplied to the preheating zone (2), under partial combustion, in order to increase the temperature for the formation of a fluidized bed. 2 The process as claimed in claim 1, wherein the reducing gas injected into the pre-heating zone comprises a portion of the export gas. 3. A process as claimed in claims 1 or 2, wherein it comprises dividing said reducing gas leaving said melting-gasifying zone into a first portion and a second portion, said second portion including entrained particles, passing said first portion of said reducing gas leaving said melting-gasifying zone into said reduction zone, forming a whirl layer with said first portion of said reducing gas leaving said melting-gasifying zone in said reduction zone, purifying said second portion of said reducing gas leaving said melting-gasifying zone by removing said entrained particles therefrom to form a purified second portion, splitting said purified second portion into a first and second part of said purified portion and passing said first part of said purified portion into said first reduction zone in a fluidized bed 4 The process as claimed in claim 3, wherein the said step of pre¬heating comprises pre-heating fine ores and ore dust to form said pre-heated charging substance. 5. The process as claimed in any one of claims 3 or 4, wherein said fine ores and ore dust are primarily comprised of at least one of hematite ores and magnetite ores. 6. The process as claimed in claimed in any one of claims 3, 4 or 5, wherein said charging substance comprising fine particulate fraction is charged by forced conveyance into at least one fluidized bed and fixed bed of said melting-gasifying zone. 7. The process as claimed in claim 6, wherein the forced air conveyance is effected by pneumatic conveying means. 8 The process as claimed in any one of claims 3 to 7, wherein purification of said second portion of said reduction gas leaving said melting-gasifying zone is effected in a hot cyclone and in a scrubber. 9. The process as claimed in any one of claims 3 to 7, wherein said second part of said purified portion of said reducing gas leaving said melting-gasifying zone is admixed as a cooling gas to said first portion fed to said reduction zone. 10 The process as claimed in any one of claims 3 to 9, wherein said reducing gas leaving said reduction zone is fed to said pre-heating zone to effect a temperature increase by partially burning said reducing gas leaving said reduction zone. 11 The process as claimed in any one of claims 3 to 10, wherein said fines from said reducing gas leaving said first reduction zone are separated to produce separated fines; and supplying said separated fines to said melting-gasifying zone. 12 The process as claimed in claim 11, wherein the separated fines are supplied by injector to said melting-gasifying zone in the region of feeding said oxygen-containing gas. 13 The process as claimed in any one of claims 3 to 12, wherein a portion of said charging substances are discharged to obtain a discharged charging substance; and supplying said discharged charging substance to said melting gasifying zone. 14 The process as claimed in claim 13, wherein the discharged charging substance is supplied to ihe melting-gasifying zone in the region of feeding of the oxygen containing gas via a sleuce system. 15 The process as claimed in any one of claims 13 or 14, wherein the fines from said reducing gas leaving said reduction zone are separated arid reduced to produce separated fines, wherein said discharged charging substance is supplied together with said separated fines. 16 The process as claimed in claim 15, wherein the entrained particles removed are fed to the melting-gasifying zone in a region between a fine-coke fluidized layer and coarse-coke fluidized layer. 17 The process as claimed in claim 16, wherein the entrained particles removed are supplied to the melting-gasifying zone via a sleuce system by an injector and via an oxygen dust burner. 18 The process as claimed in any one of claims 3 to 17, wherein said fluxes are split into a first part and a second part; and said process comprises charging said first part of said fluxes directly into said melting-gasifying zone together with coal; and charging said second part of said fluxes into said pre-heating zone together with fine ore. 19 The process as claimed in claim 13, wherein first part of said fluxes charged together with coal Is charged as coarse grains and said second part of fluxes charged together with fine ore is charged as fine grains. 20 The process as claimed in claim 19, wherein said coarse grains range between 4 mm and 12.7 rnm and said fine grains range between 2 mm and 6.3 mm. 21 The process as claimed in claim 3, wherein said reduction zone is locally separated and consecutively arranged to provide a first reduction zone and a second reduction zone preceding said first reduction zone in the sense of flow of said fine ore, and said reducing gas leaving said first reduction zone is fed to said second reduction zone; recovering a reducing gas from said second reducing zone; and feeding said reducing gas from said second reducing zone to said pre-heatirig zone. 22 The process as claimed in claim 21, wherein the reduction gas from said second reducing zone is i'ed under compression. 23 An apparatus for carrying out the process as claimed in claim 1, comprising at least one fluidized-bed reduction reactor (8, 8'), into which a conveyor duct (7) for charging substances containing iron ore and fluxes, a gas duct (17) fur a reducing gas as well as a conveyor duct (9) for the reduction product formed therein and a gas duct (30) for the topgas run, and a melter gasifier (10), into which the conveyor duct (9) carrying the reduction product from the reduction reactor (8, 8') runs and which exhibits feed ducts (11, 12) for oxygen-containing gases and carbon carriers as well as taps (15, 16)for pig iron (13) or a steel prematerial and slag (14), respectively, wherein the gas duct for reducing gas formed in the melter gasifier (10), which gas duct runs into the reduction reactor (8, 81), originates from the melter gasifier (10), and a fluidized-bed preheating reactor (1) is arranged to precede the fluidized-bed reduction reactor (8, 8') in the flow direction of the charging substances, into which fluidized-bed preheating reactor the gas duct (30) of the reduction reactor (8, 81) runs, and wherein consumed or partially consumed reducing gas may be supplied as an export gas to a consumer via a gas-discharge duct (6, 42), characterized in that the gas duct (6, 42) for the export gas, after the interposition of a CO2-scrubber (45) and a heating means (46), runs into at least one further reduction reactor (8) in order to produce hot-briquetted iron, whercfrom a gas duct is conducted to a fluidized-bed preheating reactor (1), with an ore-dust charging duct (3) running into the fluidized-bed preheating reactor (1) and a conveyor duct carrying the preheated ore dust to the reduction reactor originating from the fluidized-bed preheating reactor (1), and that a compressing and briquetting means (48, 49) is arranged to follow the reduction reactor (8) in the flow direction of the ore dust. 24 The apparatus as claimed in claim 23, wherein the melting gasifier (10) has a fluidized bed and a fixed bed and the conveying duct (90 conducting the reduction product from the reduction reactor (8, 8') into the melting-gasifier (10) comprises a pneumatic conveyor for conveying the recution product to at least one of said fluidized bed and said fixed bed, and the gas duct (17) for reducing gas formed in the melting-gasifier (10) has two branches, the first branch of which runs into a lower part of said reduction reactor (8, 8*) via a hot cyclone and the second one of which departs from the gas duct (17) at a position before the hot cyclone and enters the reduction reactor (8, 8') at a higher level. 25 The apparatus as claimed in claim 24, wherein said second gas conveyor is provided with an oxygen conveyor running into said second gas conveyor leading from said whirl-layer reduction reactor into said whirl-layer pre-heating reactor. 26 The apparatus as claimed in any one of claims 24 or 25, wherein said whirl-layer reduction reactor comprises a smaller-diameter lower part and larger-diameter upper part following said lower part via a transition means designed as a conical transition piece, said first gas conveyor entering into said conical transition piece. 27 The apparatus as claimed in any one of claims 24, 25 or 26, wherein said whirl-layer reduction reactor has a conical lower end, said second gas conveyor entering into said conical lower end. 28 The apparatus as claimed in any one of claims 24 to 27, wherein said whirl layer reduction reactor is provided with a fines discharge means provided in said whirl-layer reduction reactor on the level of said whirl-layer, a pneumatic conveying means entering into said melter gasifier on the level of said fixed bed formed therein, and a further conveying duct leading to said pneumatic conveying means. 29 The apparatus as claimed in any one of claims 24 to 28, wherein said fines discharge means provided in said whirl-layer reduction reactor on the level of said whirl-layer, a pneumatic conveying means entering into said melter gasifier on the level of said fluidized bed formed therein, and a further conveying duct leading to said pneumatic conveying means. 30 The apparatus as claimed in any one of claims 24 to 29, wherein two whirl-layer reduction reactors are provided, one whirl-layer reduction reactor being arranged upstream of the other. 31 A process substantially as herein described with reference to the accompanying drawings. 32 An apparatus substantially as herein described with reference to the accompanying drawings.

Full Text

The invention relates to a process for producing molten
from charging substances formed of iron ores and fluxes and at least
partially comprising fines, wherein the charging substances are directly reduced to sponge iron in at least one reduction zone by the whirl layer method, the sponge iron is melted in a melting-gasifying zone under supply of carbon carriers and oxygen-containing gas, and a CO and H2 ontaining reducing gas is produced, which is injected into the reduction zone, is reacted there, is withdrawn as an export gas and is supplied to a consumer, as well as a plant for carrying out the process.
A process of this kind is known, for instance, from AT-B 390 622. According to AT-B 390 622, charging substances having largely varying grain sizes are processed, the charging substances being pre-reduced and separated by wind screening into fractions of different grain sizes, which are then completely reduced separately. However, this known one-step process only offers a low thermal utilization of the reducing gas and consequently involves an elevated consumption of reducing gas. Nor is the optimum utilization of the energy chemically bound in the reducing gas feasible.
The invention has as its object to provide a process of the initially defined kind as well as a plant for carrying out the process., which enable the use of iron ores and fluxes comprising at least a share of fines, in an economic manner by using untreated coal as a carbon carrier, wherein the chemically bound energy (CO, H2-content) still contained in the reducing gas used can be utilized.
In accordance with the invention, this object is achieved with a process of the initially defined kind in that
- primarily hematite and/or magnetite fine ores and/or ore dusts are subjected to preheating by the whirl layer method in a preheating zone,
- the thus preheated charging substances are completely reduced to a major extent in at
least one consecutively arranged reduction zone,
- whereupon at least the more finely participate charging substances are charged into
the fluidized bed and/or, if desired, also into the fixed bed, of the melting-gasifying
zone by forced conveyance, preferably by pneumatic conveyance, and are melted there.
^--Accoiding to AT-B 387 403, siderite-containing and/or hydrated charging substances are calcined in a fixed-bed heating zone preceding the fixed-bed direct reduction zone, wherein, however, only coarse lumps of iron-ore-containing charging substances capable of being processed merely in the fixed bed are used for charging.
It is essential to the invention that the charging substances are processed not in the material counterflow as is the case with the known fixed-bed methods (AT-B 387 403), but in stable or circulating whirl layers, i.e., for instance, in diagonal flow, thus enabling the economic processing of fine ores and ore dusts on account of the improved energetic gas utilization. This is of importance, because, at present, about 75 % of the world's ores incurs as fine ore, which is cheaper than lumpy ore or agglomerates. According to the invention, not only reduction is effected by the whirl layer method, but also preheating. By the multi-step whirl layer method according to the invention it has become possible to use the reducing gas in an optimum manner without having to feed additional energy.
From US-A 5,082,251, a direct reduction process is known, according to which fine ores rich in iron are reduced after complex ore preparation, such as drying, screening and breaking, in a system of whirl layer reactors in cascade arrangements by aid of reformed natural gas or oil so as to obtain a very narrow grain size distribution. Subsequently, the iron powder is hot- or cold-briquetted. Smoke gas is used as the fludizing gas in the preheating stage, which is produced by burning air and natural gas;
thus, external energy must be introduced, only the sensible heat of the whirling gases being utilizable. In contrast, reduction according to the process of the invention is effected by means of solid carbon carriers,, such as coal, and hence, according to the invention, CO reduction is preponderant, whereas, according to US-A-5,082,251, the direct reduction of ore primarily is effected by H2-
A substantial advantage of the process according to the invention is to be seen in that ore preheating is effected by means of process reducing gas from the final reduction stage and not by external gas supply as according to US-A-5,082,251, which, of course, involves accordingly high costs. Another advantage of the gas control implied by the invention resides in that pre-reduction can be achieved by the reducing atmosphere in addition to preheating, a particularly efficient utilization of the reducing gases, thus, being ensured.
To cool the reducing gas formed in the melting-gasifying zone, the reducing gas, according to the invention, partially is fed directly to the reduction zone for forming a whirl layer and partially, after purification in a hot cyclone an in a scrubber, is admixed as a cooling gas to the first portion of the reducing gas fed to the reducion zone.
To control the state of fluidization of the charging substances in the reducing zone, a portion of the reducing gas advantageously is fed to the reduction zone in the region of the whirl layer and part of the portion of the reducing gas supplied to the hot cyclone is fed to the reduction zone into a fluidized bed formed in the lower part therof.
To efficiently preheat the charging substances, the reducing gas leaving the reduction zone advantageously is fed to the preheating zone, a temperature increase being effected by the partial combustion of the reducing gas.
To efficiently use the dust and fines incurring in reduction, the reducing gas withdrawn from the reduction zone advantagously is freed from fines in a reduction cyclone and the fines separated in the reduction cyclone are completely reduced to a major extent during separation and are supplied by means of an injector to the melting-gasifying zone in the region of feeding of oxygen-containing gas.
Fines that have been completely reduced in the reduction zone already prematurely, suitably are partially discharged from the whirl layer of the reduction zone and are supplied by means of an injector to the melting-gasifying zone in the region of feeding of oxygen-containing gas via a sleuce system, the portion of charging substances discharged from the whirl layer of the reduction zone suitably being supplied to the me king-gasifying zone together with the material separated in the reduction cyclone.
In doing so, the dust separated in the hot cyclone advantageously is supplied to the melting-gasifying zone in the region between a fine-coke fluidized bed forming there and a coarse-coke fluidized bed, via a sleuce system by aid of an injector and by means of an oxygen dust burner.
Suitably, the addition of fluxes is effected by charging a portion of the fluxes required for the melting process, together with the coal, directly into the melting-gasifying zone and a portion of the fluxes, together with the fine ore, into the preheating zone, wherein, advantageously, the fluxes charged together with the coal are introduced as coarse grains, preferably ranging between 4 mm and 12.7 mm, and the fluxes charged together with the fine ore are introduced in a fine-grain form, preferably ranging between 2 mm and 6.3 mm.
Particularly efficient reduction may be obtained by providing two locally separated consecutively arranged reduction zones, the reducing gas leaving the first reduction zone being conducted to the second reduction zone preceding the first reduction zone
in the sense of the fine ore flow and from there being fed to the preheating zone under compression.
To utilize the excess gas incurring in the process, the export gas leaving the preheating zone, according to a preferred embodiment, if desired, upon admixture of a portion of the reducing gas leaving the reduction zone, after CC>2 purification, is used for producing hot-briquetted iron, wherein fine ore is subjected to preheating in a preheating zone, subsequently is subjected to a largely complete reduction in at least one reduction zone and, furthermore, is supplied to a compressing and briquetting means, and the export gas, upon heating, is conducted into the at least one reduction zone under formation of a whirl bed, and, after having flown therethrough, is withdrawn from the same and is fed to the preheating zone under partial combustion with a view to temperature elevation for the purpose of forming a whirl bed.
An arrangement for carrying out the process according to the invention, comprising at least one reduction reactor, into which a conveying duct for charging substances containing iron ore and fluxes, a gas duct for a reducing gas as well as a conveying duct for the reduction product formed therein and a gas duct for the export gas enter, and comprising a melter gasifier, into which the conveying duct conducting the reduction product from the reduction reactor enters and which comprises feed ducts for oxygen-containing gases and carbon carriers as well as taps for pig iron or steel pre-material and slag, wherein the gas duct for reducing gas formed in the melter gasifier entering the reduction reactor depajts from the melter gasifier, is characterized in that the reduction reactor is designed as a whirl-layer reduction reactor and that, in the flow direction of the charging substances, a whirl-layer preheating reactor precedes the whirl-layer reduction reactor, the gas duct of the whirl-layer reduction reactor entering into the whirl-layer preheating reactor, and that a pneumatic conveying duct is
provided for conveying the sponge iron formed in the whirl-layer reduction reactor into the melter gasifier, the conveying duct entering the melter gasifier on the level of the fluidized bed and/or fixed bed.
The reduction process may be controlled via the degree of fluidization prevailing within the reduction reactor (and also within the preheating reactor) advantageously in that the whirl-layer reduction reactor comprises a lower part having a smaller diameter and an upper part following upon the lower part and having a larger diameter, the transition from the lower part to the upper part being conically designed and the gas duct for the reducing gas entering the conical transition piece, wherein the whirl-layer preheating reactor suitably has a conical lower end into which the gas duct for the reducing gas runs.
In order to be able to discharge completely reduced fines from the whirl-layer reduction reactor, the whirl-layer reduction reactor, on the level of the whirl layer, is provided with a fines discharge means, from which a conveying means leads to a pneumatic conveying means entering into the melter gasifier on the level of the fixed bed or fluidized bed formed therein.
According to a preferred embodiment, two whirl-layer reduction reactors are consecutively provided in the flow direction of the charging substances.
A particularly efficient utilization of the excess gases forming is provided if the gas duct for the export gas, after the intermediate arrangement of a CO2 scrubber and a heating means, runs into at least one reduction reactor for producing hot-briquetted iron, from which reduction reactor a gas duct is conducted into a whirl-layer preheating reactor, wherein a fine-ore charging duct enters into the whirl-layer preheating reactor and a conveying duct departs from the whirl-layer preheating reactor, conducting the
preheated fine ore to the reduction reactor, and if a compressing and briquetting means is arranged to follow the reduction reactor in the direction of the fine-ore flow.
In the following, the invention will be explained in more detail by way of three exemplary embodiments schematically illustrated in the drawing, wherein Figs. 1 to 3 each depict an advantageous embodiment of a plant according to the invention in schematic illustration.
By 1 a preheating reactor is denoted, which is designed as a whirl-layer preheating reactor and into which charging substances containing iron ore and fluxes are chargeable via a. charging duct 3 entering laterally on the level of the whirl-bed zone 2 (preheating zone). On the upper end of the shaft-likely designed whirl-layer preheating reactor 1, the gases formed therein and flowing therethrough are withdrawn via a gas discharge duct 6 equipped with a gas purifying cyclone 4 and a gas scrubber 5, such as a Venturi scrubber. These gases are available as hiqh-quality export gases having a calorific value of about 8000 kJ/Nm3 for various purposes, e.g., for the production of current with or without oxygen.
All of the charging substances preheated in the whirl-layer preheating reactor 1, via a conveying duct 7, reach a reduction reactor 8 also designed as a whirl-layer reactor and are completely reduced to a major extent in the same.
Via a pneumatic sponge-iron conveying duct 9 (including an N2 injector) - any other forced conveyance could be provided instead - the sponge iron formed in the whirl-layer reduction reactor 8 gets into a rnelter gasifier 10 by being introduced into the same on the level of a fluidized bed III, n provided in the melter gasifier and/or on the level of a fixed bed I located therebelow. The melter gasifier comprises at least one supply duct 11 for coal and fluxes as well as tuyere feeds 12 for oxygen-containing gases arranged on several levels.
Molten pig iron 13 and liquid slag 14 collect in the melter gasifier 10 below the melting-gasifying zone formed by a fixed bed I, a coarse coke fluidized bed II located thereabove, a fine coke fluidized bed in located above the latter and a killing pace IV located on top, the pig iron and the slag being tapped separately via a tapping means 15, 16 each. In the melter gasifier 10, a reducing gas is produced from the carbon carriers and from the oxygen-containing gas, which reducing gas collects in the killing space IV above the fluidized bed III and is fed to the whirl-layer reduction reactor 8 through a gas duct 17, via a frustoconical constriction of the substantially shaft-shaped whirl-layer reduction reactor 8, constituting a gas distributing bottom 9 and provided for the purpose of forming a whirl layer 18 or a whirl bed 18 (reduction zone), the reducing gas being supplied via the periphery of the constriction by means of an annular duct 20.
The large solids particles, which cannot be kept floating in the whirl layer, centrally descend due to the effect of gravity and are withdrawn through a central solids discharge 21. This central solids discharge 21 is configured such that, via a radial gas feed means 22, a fixed-bed flow is formed into the cylindrical vessel part 23 having a conical bottom 24 and arranged below the frustoconical gas distributing bottom 19 such that the reduction even of large particles can be achieved to a satisfactory extent.
Due to the frustoconical shape of the gas distributing bottom 19, the clear tube velocity changes with the height As a result, a special grain size distribution adjusts over the height of the gas distributing bottom 19. By appropriately arranging the tuyeres in the gas distributing bottom 19, an internally circulating whirl layer can, thus, be formed, where the gas velocity is higher in the center than on the periphery. The formation of a whirl layer of this type may be used both for the reduction reactor 8 and for the preheating reactor 1.
A portion of the reducing gas leaving the melter gasifier 10 is subjected to purification in a hot cyclone 25, to cooling in a consecutively arranged scrubber 26, and, via a compressor 27, is again admixed to the reducing gas leaving the melter gasifier 10 via a gas duct 28. The dust separated in the hot cyclone 25 is returned into the melter gasifier 10 via an N2 injector 29. A portion of the still uncooled reducing gas leaving the hot cyclone 25 reaches the whirl-layer reduction reactor 8 through its cylindrical vessel part 23 via the gas feed means 22 formed by an annular duct
The gas withdrawn from the whirl-layer reduction reactor 8, via a gas duct 30, is fed to a reduction cyclone 31, in which fines still contained in the reducing gas are separated and reduced completely. These fines are introduced into the melter gasifier 10 approximately on the level of the upper end of the fixed bed I via a conveying duct 32 and an N2 injector 33.
The partially oxidized reducing gas emerging from the reduction cyclone 8, via the gas duct 30, gets into the whirl-layer preheating reactor 1, wherein, however, part of the same is burnt for heating the reducing gas in a combustion chamber 34, into which a duct 35 feeding an oxygen-containing gas enters.
From the whirl-layer reduction reactor 8, a portion of the completely reduced charging substances is withdrawn on the level of the whirl bed 18 by means of a worm conveyor 36 and, preferably together with the fines coming from the reduction cyclone 31, is introduced into the melter gasifier 10 approximately on the level of the upper end of the fixed bed I by means of a conveying duct 37 via an N2 injector 33.
The finely paxticulate material separated in the cyclone 4 of the export gas discharge duct 6 is charged via a conveying duct 38 including sleuces 39 - which are also provided in the other conveying ducts 32, 37 for the partially or completely reduced
material-through the annular duct 20 feeding the reducing gas into the whirl-layer reduction reactor 8
Accordingly the present invention relates to a method for producing hot briquetted iron from charging substances formed from iron ores and fluxes and having, at least partially, a content of fines, wherein the charging substances are subjected to preheating according to the fluidized-bed method in a preheating zone (2), are directly and to a large extent completely reduced to sponge iron in at least one reduction zone (18, 18") according to the fluidized-bed method, the sponge iron is charged into a melt-down gasification zone (I to IV), is melted undersupply of carbon carriers and an oxygen containing gas, and a CO- and H2-containing reducing gas is generated, which is supplied to the reduction zone (18, 18'), is reacted there, is withdrawn as an export gas and is supplied to a consumer, characterized in that, after CO2- purification, the export gas emerging from the preheating zone (2) is utilized for the generation of hotbriquetted iron, optionally after admixing a portion of the reducing gas emerging from the reduction zone (18), wherein fine ore is subjected to preheating in a preheating zone (2), subsequently is subjected to largely a complete reduction in at least one reduction zone (18) and furthermore is supplied to a compressing and briquetting means (48, 49) and, after heating, the export gas is conducted into the at least one reduction zone, under the formation of a fluidized bed (18), and is withdrawn from the same after having passed through the latter and is supplied to the preheating zone (2), under partial combustion, in order to increase the temperature for the formation of a fluidized bed.
Accordingly the present invention also relates to an apparatus for carrying out the process as claimed in claim 1, comprising at least one fluidized-bed reduction reactor (8, 8'), into which a conveyor duct (7) for charging substances containing iron ore and fluxes, a gas duct (17) for a reducing gas as well as a conveyor duct (9) for the reduction product formed therein and a gas duct (30) for the topgas run, and a melter gasifier (10), into which the conveyor duct (9) carrying the reduction product from the reduction reactor (8, 8') runs and which exhibits feed ducts (11, 12) for oxygen-containing gases and carbon carriers as well as taps (15, 16)for pig iron (13) or a steel prematerial and slag (14), respectively, wherein the gas duct for reducing gas formed in the melter gasifier (10), which gas. duct runs into the reduction reactor (8, 8'), originates from the melter gasifier (10), and a fluidized-bed preheating reactor (1) is arranged to precede the fluidized-bed reduction reactor (8, 81) in the flow direction of the charging substances, into which fluidized-bed preheating reactor the gas duct (30) of the reduction reactor (8, 8') runs, and wherein consumed or partially consumed reducing gas may be supplied as an export gas to a consumer via a gas-discharge duct (6, 42), characterized in that the gas duct (6, 42) for the export gas, after the interposition of a CCb-scrubber (45) and a heating means (46), runs into at least one further reduction reactor (8) in order to produce hot-briquetted iron, wherefrom a gas duct is conducted to a fluidized-bed preheating reactor (1), with an ore-dust charging duct (3) running into the fluidized-bed preheating reactor (1) and a conveyor duct carrying the preheated ore dust to the reduction reactor originating from the fluidized-bed preheating reactor (1), and that a compressing and briquetting means (48, 49) is arranged to follow the reduction reactor (8) in the flow direction of the ore dust.
The plant according to Fig 1, in detail, functions as follows:
The fine ore treated - sieved and dried - and having a grain size distribution of, for instance,
- 0.044 mm = approx. 20 % 0.044 - 6.3 mm = approx. 70 % 6.3 -12.7 mm = approx. 10%
and a moisture content of approximately 2 % is charged into the preheating reactor 1 pneumatically or by aid of a steep belt or vertical conveyor. There, it is prehated to a temperature of about 850°C in the whirl-bed zone 2 and optionally is pre-reduced on account of the reducing atmosphere to about the wuestite stage.
For this pre-reduction procedure, the reducing gas is to contain at least 25 % CO + H2 in order to have sufficient reducing power.
Subsequently, the preheated and optionally pre-reduced fine ore flows into the reduction reactor 8 - preferably due to gravity -, in the whirl layer or whirl bed 18 of which the fine ore is largely reduced to the Fe stage at a temperature of about 850° C. For this reduction procedure, the gas is to have a content of CO + H2 of at least 68 %.
In the reduction reactor 8, screening of the fine ore takes place, the portion of below 0.2 mm being entrained by the reducing gas into the reduction cyclone 31. There, the complete reduction of the fine ore of below/ 0.2 mm occurs during the separation of the solids by the cyclone effect
The finer solids portion discharged from the whirl layer 18 of the reduction reactor 8 by aid of the discharge worm 36 is supplied to the melter gasifier 10 in the region of
the blow-in planes of the oxygen-containing gases via sleuces 39, together with the fine ore separated in the reduction cyclone 31, by aid of the N2 injector 33.
The coarser solids portion from the lower region of the reduction reactor 8 is blown or charged into the melter gasifier 10 in the region of the fine-coke fluidized bed III via sleuces 39 and by aid of the N2 injector 9 or by means of gravity discharge.
The dust separated in the hot cyclone 25 (primarily containing Fe and C) is fed to the melter gasifier 10 in the region between the fine-coke fluidized bed HI and the coarse-coke fluidized bed n via sleuces 39 by aid of the N2 injector 29 and by means of an oxygen dust burner.
For the purpose of preheating and calcining, the fluxes required for the process are charged as coarse grains, preferably having grain sizes ranging between 4 and 12.7 mm, via the coal path (11) and as fine grains, preferably having grain sizes ranging between 2 and 6.3 mm, via the fine-ore path (3).
For fine ores requiring longer reduction times, a second (as well as, if required, a third) whirl-layer reduction reactor 8' including an additional reduction cyclone 31' is provided in series or in succession to the first reduction reactor 8, as is illustrated in Fig. 2. The fine ore is reduced to the wuestite stage in the second reduction reactor 8' and to the Fe stage in the first reduction reactor 8.
In this case, the solids portion discharged from the whirl layer 18' of the second reduction reactor by aid of the discharge worm 36' is charged into the first reduction reactor 8 by gravity, together with the coarser solids portion from the lower region of the second reduction reactor 8'. The fine ore separated in the second reduction cyclone 31' is supplied to the melter gasifier 10 in the region of the blow-in planes of the oxygen-containing gases by aid of the N2 injector 33, together with the fine ore separated in the first reduction cyclone 31.
If, when using two whirl-layer reduction reactors 8, 8' and two reduction cyclones 31,31', the operational pressure does not suffice to balance out pressure losses in the system, the gas mixture required for the preheating reactor 1, according to the invention, is brought to the necessary pressure by aid of a compressor 40. In this case, the gas from the second reduction cyclone 31' is cleaned in a scrubber 41. However, in the following, only a partial stream of the gas is compressed - a portion being withdrawn through duct 42 as export gas - and is appropriately mixed with an oxygen-containing gas fed through duct 44 in a mixing chamber 43 such that a partial combustion of the reducing gas subsequently can occur in the preheating reactor 1 for the purpose of attaining the fine-ore preheating temperature required.
The high-quality export gas from the pig iron production may be used for the production of current with or without oxygen, as indicated above. According to a preferred embodiment of the invention, which is represented in Fig. 3, the export gas, after CO2 scrubbing 45 and preheating 46 to about 850°C, is re-used as a reducing gas, in the following manner:
To produce hot-briquetted iron, fine ore of the same specification as used for the production of pig iron is preheated and reduced by the reducing gas in the same aggregates as used in pig iron production . The completely reduced grain fractions from the at least one reduction reactor 8 and from the reduction cyclone 31 are blown into a charging bunker 47 by aid of N2 injectors 33. Alternatively, the coarser grain fraction can be charged from the lower region of the reduction reactor 8 into the charging bunker 47 by a gravity discharge.
After this, the completely reduced fine ore having a degree of metallization of about 92 % and a temperature of at least 750°C reaches a roll briquetting press 49 due to gravity via a pre-compressing worm 48 including a controllable motor.
In the following examples, typical characteristic data of the process according to the invention obtained in operating the plants according to the embodiments represented in Figs. 1 to 3 are summarized.
Example: Coal analysis (dry analysis values)
C 77 %
H 4.5 %
N 1.8 %
O 7.6 %
S 0.5 %
ashes 9.1 %
eg* 61.5%
Ore analysis (moist analysis values)
Fe 62.84 %
Fe2O3 87.7 %
CaO 0.73 %
MgO 0.44 %
SiO2 6.53 %
A12O3 0.49 %
MnO 0.15%
losses on ignition 0.08 %
moisture
2 %
Grain size distribution of fine ore
+ 10 mm 0 %
10-6 mm 5.8 %
6-2mm 44.0 %
2-0.63 mm 29.6 %
0.63-0.125 mm 13.0 %
-0.125mm 7.6 %
Fluxes (dry analysis values)
CaO 45.2 %
MgO 9.3 %
SiO2 1.2 %
A12O3 0.7 %
MnO 0.6 %
Fe2O3 2.3 %
losses on ignition 39.1 %
For the production of 42 tons of pig iron/hour in the plant according to Fig. 1,42 tons of coal/hour are gassed with 29,000 Nm3O2/hour. The ore consumption therefor amounts to 64 tons/hour and the consumption of fluxes is 14 tons/hour.
In addition to iron, the pig iron produced has the following composition:
C 4.2 %
Si 0.4 %
P 0.07 %
Mn 0.22 %
S 0.04 %
The export gas from the pig iron plant incurs at 87,000 Nm^/hour, having the following analysis:
CO 36.1 %
CO2 26.9 %
H2 16.4 %
H20 1.5 %
N2 + Ar 18.1 %
CH4 I %
H2S ' 0.02 %
Calorific value 6780 kJ/Nm3
When further utilizing the export gas from the pig iron plant for the production of hot-briquetted iron according to Fig. 3, 29 tons of hot-briquetted iron/hour can be produced. The amount of recycled gas required therefor is 36,000 Nm3/hour. The hot-briquetted sponge iron has the following analysis values:
Metallization 92 %
C 1 %
S 0.01 %
P 0.03 %
The amount of export gas from the plant for the production of hot-briquetted iron is 79,000 Nm3/hour, the gas having the following composition:
CO 21.6 %
O>2 44.1 %
H2 10.6 %
H2O 2.8 %
N2 + Ar 19.9 %
CH4 1 %
Calorific value 4200 kJ/Nm3
The necessary electric input of the pig iron plant and of the plant for the production of hot-briquetted iron is 23 MW. The export gas after the plant for the production of hot-briquetted iron corresponds to a thermal output of 145 MW.

CLAIM:
1. A method for producing hot briquetted iron from charging substances formed from iron ores and fluxes and having, at least partially, a content of fines, wherein the charging substances are subjected to preheating according to the fluidized-bed method in a preheating zone (2), are directly and to a large extent completely reduced to sponge iron in at least one reduction zone (18, 18') according to the fluidized-bed method, the sponge iron is charged into a melt-down gasification zone (I to IV), is melted undersupply of carbon carriers and an oxygen containing gas, and a CO- and H2-containing reducing gas is generated, which is supplied to the reduction zone (18, 18'), is reacted there, is withdrawn as an export gas and is supplied to a consumer, characterized in that, after COa- purification, the export gas emerging from the preheating zone (2) is utilized for the generation of hotbriquetted iron, optionally after admixing a portion of the reducing gas emerging from the reduction zone (18), wherein fine ore is subjected to preheating in a preheating zone (2), subsequently is subjected to largely a complete reduction in at least one reduction zone (18) and furthermore is supplied to a compressing and briquetting means (48, 49) and, after heating, the export gas is conducted into the at least one reduction zone, under the formation of a fluidized bed (18), and is withdrawn

from the same after having passed through the latter and is supplied to the preheating zone (2), under partial combustion, in order to increase the temperature for the formation of a fluidized bed.
2 The process as claimed in claim 1, wherein the reducing gas injected into the pre-heating zone comprises a portion of the export gas.
3. A process as claimed in claims 1 or 2, wherein it comprises dividing said reducing gas leaving said melting-gasifying zone into a first portion and a second portion, said second portion including entrained particles, passing said first portion of said reducing gas leaving said melting-gasifying zone into said reduction zone, forming a whirl layer with said first portion of said reducing gas leaving said melting-gasifying zone in said reduction zone, purifying said second portion of said reducing gas leaving said melting-gasifying zone by removing said entrained particles therefrom to form a purified second portion, splitting said purified second portion into a first and second part of said purified portion and passing said first part of said purified portion into said first reduction zone in a fluidized bed 4 The process as claimed in claim 3, wherein the said step of pre¬heating comprises pre-heating fine ores and ore dust to form said pre-heated charging substance.
5. The process as claimed in any one of claims 3 or 4, wherein said
fine ores and ore dust are primarily comprised of at least one of
hematite ores and magnetite ores.
6. The process as claimed in claimed in any one of claims 3, 4 or 5,
wherein said charging substance comprising fine particulate
fraction is charged by forced conveyance into at least one fluidized
bed and fixed bed of said melting-gasifying zone.
7. The process as claimed in claim 6, wherein the forced air
conveyance is effected by pneumatic conveying means.
8 The process as claimed in any one of claims 3 to 7, wherein purification of said second portion of said reduction gas leaving said melting-gasifying zone is effected in a hot cyclone and in a scrubber.
9. The process as claimed in any one of claims 3 to 7, wherein said second part of said purified portion of said reducing gas leaving said melting-gasifying zone is admixed as a cooling gas to said first portion fed to said reduction zone.
10 The process as claimed in any one of claims 3 to 9, wherein said
reducing gas leaving said reduction zone is fed to said pre-heating
zone to effect a temperature increase by partially burning said
reducing gas leaving said reduction zone.
11 The process as claimed in any one of claims 3 to 10, wherein said
fines from said reducing gas leaving said first reduction zone are
separated to produce separated fines; and supplying said
separated fines to said melting-gasifying zone.
12 The process as claimed in claim 11, wherein the separated fines
are supplied by injector to said melting-gasifying zone in the region
of feeding said oxygen-containing gas.
13 The process as claimed in any one of claims 3 to 12, wherein a
portion of said charging substances are discharged to obtain a
discharged charging substance; and supplying said discharged
charging substance to said melting gasifying zone.
14 The process as claimed in claim 13, wherein the discharged
charging substance is supplied to ihe melting-gasifying zone in the
region of feeding of the oxygen containing gas via a sleuce system.
15 The process as claimed in any one of claims 13 or 14, wherein the
fines from said reducing gas leaving said reduction zone are
separated arid reduced to produce separated fines, wherein said
discharged charging substance is supplied together with said
separated fines.
16 The process as claimed in claim 15, wherein the entrained
particles removed are fed to the melting-gasifying zone in a region
between a fine-coke fluidized layer and coarse-coke fluidized layer.
17 The process as claimed in claim 16, wherein the entrained
particles removed are supplied to the melting-gasifying zone via a
sleuce system by an injector and via an oxygen dust burner.
18 The process as claimed in any one of claims 3 to 17, wherein said
fluxes are split into a first part and a second part; and said process
comprises charging said first part of said fluxes directly into said
melting-gasifying zone together with coal; and charging said
second part of said fluxes into said pre-heating zone together with
fine ore.
19 The process as claimed in claim 13, wherein first part of said
fluxes charged together with coal Is charged as coarse grains and
said second part of fluxes charged together with fine ore is charged
as fine grains.
20 The process as claimed in claim 19, wherein said coarse grains
range between 4 mm and 12.7 rnm and said fine grains range
between 2 mm and 6.3 mm.
21 The process as claimed in claim 3, wherein said reduction zone is
locally separated and consecutively arranged to provide a first
reduction zone and a second reduction zone preceding said first
reduction zone in the sense of flow of said fine ore, and said
reducing gas leaving said first reduction zone is fed to said second
reduction zone; recovering a reducing gas from said second
reducing zone; and feeding said reducing gas from said second
reducing zone to said pre-heatirig zone.
22 The process as claimed in claim 21, wherein the reduction gas
from said second reducing zone is i'ed under compression.
23 An apparatus for carrying out the process as claimed in claim 1,
comprising at least one fluidized-bed reduction reactor (8, 8'), into
which a conveyor duct (7) for charging substances containing iron
ore and fluxes, a gas duct (17) fur a reducing gas as well as a
conveyor duct (9) for the reduction product formed therein and a gas duct (30) for the topgas run, and a melter gasifier (10), into which the conveyor duct (9) carrying the reduction product from the reduction reactor (8, 8') runs and which exhibits feed ducts (11, 12) for oxygen-containing gases and carbon carriers as well as taps (15, 16)for pig iron (13) or a steel prematerial and slag (14), respectively, wherein the gas duct for reducing gas formed in the melter gasifier (10), which gas duct runs into the reduction reactor (8, 81), originates from the melter gasifier (10), and a fluidized-bed preheating reactor (1) is arranged to precede the fluidized-bed reduction reactor (8, 8') in the flow direction of the charging substances, into which fluidized-bed preheating reactor the gas duct (30) of the reduction reactor (8, 81) runs, and wherein consumed or partially consumed reducing gas may be supplied as an export gas to a consumer via a gas-discharge duct (6, 42), characterized in that the gas duct (6, 42) for the export gas, after the interposition of a CO2-scrubber (45) and a heating means (46), runs into at least one further reduction reactor (8) in order to produce hot-briquetted iron, whercfrom a gas duct is conducted to a fluidized-bed preheating reactor (1), with an ore-dust charging duct (3) running into the fluidized-bed preheating reactor (1) and a conveyor duct carrying the preheated ore dust to the reduction reactor originating from the fluidized-bed preheating reactor (1), and that a compressing and briquetting means (48, 49) is arranged
to follow the reduction reactor (8) in the flow direction of the ore dust.
24 The apparatus as claimed in claim 23, wherein the melting gasifier
(10) has a fluidized bed and a fixed bed and the conveying duct (90
conducting the reduction product from the reduction reactor (8, 8')
into the melting-gasifier (10) comprises a pneumatic conveyor for
conveying the recution product to at least one of said fluidized bed
and said fixed bed, and the gas duct (17) for reducing gas formed
in the melting-gasifier (10) has two branches, the first branch of
which runs into a lower part of said reduction reactor (8, 8*) via a
hot cyclone and the second one of which departs from the gas duct
(17) at a position before the hot cyclone and enters the reduction
reactor (8, 8') at a higher level.
25 The apparatus as claimed in claim 24, wherein said second gas
conveyor is provided with an oxygen conveyor running into said
second gas conveyor leading from said whirl-layer reduction
reactor into said whirl-layer pre-heating reactor.
26 The apparatus as claimed in any one of claims 24 or 25, wherein
said whirl-layer reduction reactor comprises a smaller-diameter
lower part and larger-diameter upper part following said lower part
via a transition means designed as a conical transition piece, said
first gas conveyor entering into said conical transition piece.
27 The apparatus as claimed in any one of claims 24, 25 or 26,
wherein said whirl-layer reduction reactor has a conical lower end,
said second gas conveyor entering into said conical lower end.
28 The apparatus as claimed in any one of claims 24 to 27, wherein
said whirl layer reduction reactor is provided with a fines discharge
means provided in said whirl-layer reduction reactor on the level of
said whirl-layer, a pneumatic conveying means entering into said
melter gasifier on the level of said fixed bed formed therein, and a
further conveying duct leading to said pneumatic conveying
means.
29 The apparatus as claimed in any one of claims 24 to 28, wherein
said fines discharge means provided in said whirl-layer reduction
reactor on the level of said whirl-layer, a pneumatic conveying
means entering into said melter gasifier on the level of said
fluidized bed formed therein, and a further conveying duct leading
to said pneumatic conveying means.
30 The apparatus as claimed in any one of claims 24 to 29, wherein
two whirl-layer reduction reactors are provided, one whirl-layer
reduction reactor being arranged upstream of the other.
31 A process substantially as herein described with reference to the accompanying drawings.

32 An apparatus substantially as herein described with reference to the accompanying drawings.

Documents:

547-del-2001-abstract.pdf

547-del-2001-claims.pdf

547-del-2001-correspondence-others.pdf

547-del-2001-correspondence-po.pdf

547-del-2001-description (complete).pdf

547-del-2001-form-1.pdf

547-del-2001-form-13.pdf

547-del-2001-form-18.pdf

547-del-2001-form-2.pdf

547-del-2001-form-3.pdf

547-del-2001-form-5.pdf

547-del-2001-gpa.pdf

547-del-2001-petition-137.pdf

547-del-2001-petition-138.pdf

547-del-2001-petition-others.pdf

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Patent Number

230507

Indian Patent Application Number

547/DEL/2001

PG Journal Number

11/2009

Publication Date

13-Mar-2009

Grant Date

27-Feb-2009

Date of Filing

03-May-2001

Name of Patentee

VOEST-ALPINE INDUSTRIEANLAGENBAU GMBH

Applicant Address

TURMSTRASSE 44, A-4020 LINZ, AUSTRIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	WERNER KEPPLINGER	7 LAHHOLDSTRASSE, A-4060 LEONDING, AUSTRIA
2	PANAJIOTIS MATZAWRAKOS	30 SCHIFFMANNSTRASSE, A-4020 LINZ, AUSTRIA.
3	JOHNNES SCHENK	8 KNABENSEMINARSTRASSE, A-4040 LINZ, AUSTRIA.
4	DIETER SIUKA	16 LINZERSTRASSE, A-4501 NEUHOFEN, AUSTRIA.
5	CHRISTIAN BOHM	5 STADTPLATZ, A-4600 WELS, AUSTRIA.

PCT International Classification Number

C21B 15/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA