VЕRFАНRЕN ZUМ НЕRSТЕLLЕN VОN ЕISЕNSСНМЕLZЕN

The invention concerns a procedure for manufacturing iron smelts, in particular from steel melts, by load-wise melting of steel girders, i.e. eisenhältigem material, in a metallurgical Gefäß by at least partially energy brought in by at least one arc, as well as a plant for the execution of the procedure.

From the DE-C 3,609,923 a procedure and a device are well-known for sequential melts from scrap iron to rawsteel, whereby the warmth of the Ofengases is used for heating the scrap iron up. The scrap iron is preheated in one centrically on the open-hearth furnace put on pit and brought in central into the open-hearth furnace. Around the pit electrodes are arranged in the circle, with whose assistance the scrap iron is melted. Here the side panel of the open-hearth furnace is exposed to a very high thermal load, since the arcs between the centrically brought in scrap iron column and the walls of the open-hearth furnace burn. It comes to a increased Verschleiß the fireproof lining, from which a relatively short life span of the open-hearth furnace results. Further goes groß it part of the brought in energy by radiation to the furnace walls lost.

A similar device, with which a melt chargenweise is manufactured, is well-known from the USA 2,382,534.

A plant with a direct current arc furnace, one on the Ofengefäß the arc furnace put on pit and into the arc furnace rising up electrodes, which are movable in electrode longitudinal direction, is also diagonal from the FR-A-2 611,876 admits the electrodes are symmetrically concerning the vertical axle of the furnace arranged. The inclination of the electrodes to the vertical one is adjusted under an angle from preferably 5 to 15 degrees. Scrap iron or other metallic material is brought from above by the pit into the direct current arc furnace, whereby the material in the pit is preheated by means of the furnace exhaust gases.

The invention aims at the avoidance of the disadvantages and difficulties specified above and places themselves the task to create a procedure as well as a plant to the execution of the procedure which particularly favorable utilization of the brought in energy under large indulgence of the metallurgical Gefäß it make possible. In particular specific Betriebsund capital outlays (also change costs) is during the electric steel making particularly by smaller electric power consumption and shortening Schmelzbzw. Cycle time in the comparison to the conventional arc fusion procedure low its.

This task becomes erfindungsgemäß by the combination of the following characteristics solved:

• Chargieren of a first subset of the total employment of the steel girders under formation of a pouring cone within the center range,
• Melt a central crater into the pouring cone formed by the first subset with the help of next to the town centre brought in arc energy,
• Chargieren at least a further subset into the central crater with anschließ endem however times melting of a central crater and
• complete melting of the still firm steel girders with the help of more center far away and wind closer brought in arc energy, which is bring inable by means of tiltable electrodes,
• on which the tap after a carbon elimination and/or purifying takes place if necessary.

Substantially for that erfindungsgemäß e procedure is the Chargieren in subsets, which make it possible, the energy brought in over the arc during almost the entire fusion process under screen of the Gefäß would wind to take up. Thereby a considerable reduction of the Verschlei&szlig results; it the fireproof lining of the metallurgical Gefäß it as well as a considerable reduction of the calorific losses. In combination with as early a formation of a foamed slag as possible these effects are still strengthened. During only the edge zone melting taking place toward end of the fusion process it comes due to the foamed slag likewise to no direct load of the Gefäß would wind by the brought in arc energy.

Zweckmäß industrial union become the utilization of the heat capacity of the Prozeß gas the steel girders before the Chargieren into the metallurgical Gefäß into a preheating pit brought in, by from the metallurgical Gefäß taken off heiß EN Prozeß gas washed and/or preheated and anschließ end into the metallurgical Gefäß heiß chargiert.

For the production of steel for the production of steel Schlackenbildner and carbon carriers are chargiert if necessary favourably, preferably in subsets.

A subset of the Schlackenbildner is already chargiert favourably with the first Teimenge of the steel girders under as early a formation of a foamed slag as possible.

An optimal utilization of the energy content of developing Prozeß gas is given, if Prozeß gas by supplying a sauerstoffhältigen gas into those and/or on the foamed slag and/or above the same into the metallurgical Gefäß and/or into the preheating pit to be after-burned.

A further saving at electricity läß t thereby obtain themselves, daß melting the first subset by injecting a sauerstoffhältigen gas is supported.

Also melting that is preferred the first subset of in the following chargierten subset (n) supported by injecting a sauerstoffhältigen gas.

Preferably a remainder melt in the metallurgical Gefä&szlig becomes; left, and the first subset into the remainder melt chargiert.

Zweckmäß industrial union as steel girders mixture scrap iron and/or fine scrap iron and/or Schrederschrott are used, whereby the steel girders are only small polluted with organic portions, whereby the Prozeß gas from dioxins and other pollutants are as far as possible free and at relatively little expenditure to be disposed of can.

A preferential variant is characterized, da&szlig by it; as steel girders mixture scrap iron and/or fine scrap iron and/or Schrederschrott (steel girder I) on the one hand and sponge iron (steel girder II) to be on the other hand separated and independently used, whereby the first subset of steel girders I as well as if necessary of steel girders II and the further (n) subset (of n) by steel girders II is at least partly formed and/or becomes, whereby favourably only the steel girders I of from the metallurgical Gefäß taken off heiß EN exhaust gases flows around and anschließ end into this heiß it is chargiert against what the steel girders II, which may not be reoxidiert e.g., without preliminary heating by the Prozeß gas - at ambient temperature or also heiß , e.g. with the Heiß employment of sponge iron from an upstream direct reduction process plant - to be chargiert.

Zweckmäß industrial union is accomplished a ground flushing with inert gas.

Gemäß a sauerstoffhältiges gas is injected to a preferential variant over at least an in/a blowing up lance and/or a nozzle and/or a Unterbaddüse into the melt.

Preferably fine-grained materials, like steel girders, are injected carbon carriers and/or Schlackenbildner, by at least an in/a blowing up lance and/or a nozzle and/or a Unterbaddüse and/or a hollow electrode using a feed gas into the Metallbad.

As fine-grained steel girders come e.g. iron carbide, sponge iron under grain, hut dust and if necessary ore into consideration, as fine-grained carbon carriers e.g. fine coal, fine coke and prepared organic light parliamentary groups.

Preferably the preheating temperature of the steel girders (steel girder I) by choice of the length of the retention time of the steel girders (steel girder I) becomes adjusted in the preheating pit. Thereby succeeds in simple way, unwanted features, like scaling, a gluing and/or a hanging of the scrap iron to in the pit to avoid.

Gemäß a preferential variant becomes the preheating temperature of the steel girders (steel girder I) by choice of quantity, composition and temperature from the metallurgical Gefäß taken off Prozeß gas adjusted.

A plant for manufacturing iron smelts, in particular of steel melts, is characterized by the following combination of characteristics:

• an iron smelt taking up metallurgical Gefäß ,
• at least a stationary, steel girder taking up pit, that into the metallurgical Gefäß over its covers by means of an enclosure flows and
• into the metallurgical Gefäß from above rising up electrodes, during manufacturing iron smelts of one toward to the Gefäß center arranged position in more near to the wall of the metallurgical Gefäß there arranged position is tiltable.

Here preferably is the metallurgical Gefäß tiltably.

Gemäß a preferential execution form is the metallurgical Gefäß elevation, senkund displaceable.

A plant, with which a particularly short cycle time is attainable, is characterized, da&szlig by it; the pit over an opening into the metallurgical Gefä&szlig, arranged within the center range of the cover; flows and daß several electrodes the pit surround, preferably in radialsymmetrical arrangement, and by the cover into the inside of the metallurgical Gefäß rise up.

Here are zweckmäß industrial union the electrodes in one to the metallurgical Gefäß radialarranged vertical level tiltable, preferably over a range, of the vertical one outgoing into one toward for the center of the metallurgical Gefäß it under 30° to the vertical one arranged position A into around max. 10° of the vertical one a deviating, after auß EN arranged position C.

To the achievement of an efficient preliminary heating of the steel girders (steel girder I) favourably the shutoff device arranged at the pit delta is gas permeable and a gas derivative at the upper pit end intended.

Around e.g. sponge iron, lime and/or coal separately from preheated scrap iron into the metallurgical Gefäß to chargieren to be able, is gemäß a preferential execution form to a central pit, which is provided with the gas-permeable shutoff device, at least a laterally neighbouring Chargierschacht intended, that over the cover of the metallurgical Gefäß it by means of one preferably gas densities enclosure into the metallurgical Gefäß flows, whereby zweckmäß industrial union the lower part of the Chargierschachtes with a diagonal, for the center of the metallurgical Gefäß it arranged Auslaufschurre is provided.

Preferably are from the side and/or by the cover into the metallurgical Gefäß bring inable blast lances and/or nozzles for a sauerstoffhältiges gas intended.

For adjustment a desired preheating temperature of the steel girders (steel girder I) favourably at least one nozzle for the supply of sauerstoffhältigem and/or stickstoffhältigem gas is intended in the steel girders I the taking up pit.

A simple mode of operation that erfindungsgemäß EN plant is given if the metallurgical Gefäß on remote cylinders in relation to the foundation supported is, preferably on three remote cylinders. Here the metallurgical Gefä&szlig is favourable; in fusion position by means of laterally bolting device pins applicable in its wall fixably, whereby at least two bolting device pins under formation of a drag axis for the metallurgical Gefäß (e.g. to the tap) to each other escape-end are arranged, and the bolting device pins by means of a servo unit from one into the wall of the metallurgical Gefäß it decisive bolting device position into a withdrawn, the metallurgical Gefäß releasing position and are in reverse bringable.

The plant is characterized favourably for the achievement of a high availability with as small a capital outlays as possible by one to below the metallurgical Gefäß it mobile cars, on that alternatively a pan or the metallurgical Gefäß even removably and by means of the car are displaceable.

The invention is in the following described on the basis the design more near, whereby Fig. 1 a vertical axial section by one erfindungsgemäß e plant and Fig. 2 one gemäß the line II-II of the Fig. 1 led cut in schematic representation illustrate. Fig. a side view that shows 3 erfindungsgemäß EN plant. The Fig. 4 and 5 illustrates the support of the metallurgical Gefäß it in relation to the foundation, whereby Fig. 4 a vertical axial section by the metallurgical Gefäß and Fig. 5 one gemäß the line V-V of the Fig. 4 led cut shows. The figure row 6 A to 6g illustrates schematically that erfindungsgemäß e procedure.

With 1 is a Ofengefä&szlig provided with a fireproof lining 2; an electric-arc furnace designates 3, which is provided with an oriel tap 4. The ground 5 of the electric-arc furnace 3 is curved trained as the admission of the melt 6. It exhibits if necessary a ground anode 7.

As from the Fig. , is the Ofengefä&szlig is evident to 4 and 5; 1 over its ground 5 by means of three argument cylinders 8, 9 in relation to the foundation 10 supported. It can be lifted and lowered with the help of the argument cylinders 8, 9, for example on one below the Ofengefäß it 1 displaceable car 11, on which also a pan is removable 12, to be touched down and with the help of the car 11 along rails 13 be horizontal proceeded. Thereby partial filling of the Ofengefä&szlig becomes; it 1 of the electric-arc furnace 3 over a scrap iron basket makes possible, what in particular with heavy and bulky scrap iron, how Brammenund is/or club remainders, package scrap iron etc. von Vorteil. Further thereby repairs leave themselves in simple way would drive through, and it knows also the Ofengefäß 1 with the occurrence of a damage to be particularly fast replaced.

The car 11 is in such a way arranged, daß it either the pan 12 below the tap 4 bring or the Ofengefäß 1 to take up can. The car 11 is in the Grundriß U-shaped trained. Thus it is possible, the car 11 - without pan 12 - complete under the Ofengefäß to move 1. The electric-arc furnace, i.e. its Ofengefäß 1, is fixable by means of four bolting device pins 14, which are applicable in at its side panel 15 planned supports 16, in raised situation - the operating position -. These bolting device pins 14 are by means of actuation equipments 17, as for example argument cylinders, engagable in recesses of the supports 16 and/or from these backdrawable. As from Fig. , swore in each case two the bolting device pin 14, whereby these pins form drag axes 18, are evident to 5 around those the Ofengefäß 1 is tiltable, soferne two escape-ends bolting device pin 14 in each case into the recesses of the corresponding supports 16 is inserted. The lagging can be accomplished by subjecting the appropriate argument cylinders 8.

The electric-arc furnace 3 exhibits one hebund lowerable cover 19, that on the Ofengefäß 1 rests. The cover 19 is provided with a central opening 20, above which a scrap iron preheating pit 21 for mixture scrap iron 22 is intended. This scrap iron preheating pit 21 is attached at the upper end to a gas departure line 23. A Chargieröffnung 24 for bringing in the mixture scrap iron 22 into the scrap iron preheating pit 21 is scarcely under it. At the lower end the scrap iron preheating pit 21 a gas-permeable is zweckmä&szlig and; industrial union water-cooled shutoff device 25 intended, for example in an educated manner by tiltable or adjustable Roststäben is covered and the opening the 20.

With the help of this shutoff device 25 in the scrap iron preheating pit 21 brought the mixture scrap iron 22 can held back or into the Ofengefäß 1 to be chargiert. The stationary scrap iron preheating pit 21 is carried by a structural steelwork, which is illustrated not more near. At this structural steelwork also the cover can be lowerable stored 19 hebund.

Like in particular from Fig. 2 to recognize is, are laterally directly neighbouring to the scrap iron preheating pit 21 Chargierschächte 26, 27 on the one hand for bringing in aggregates 28 and/or carbon carriers and on the other hand for bringing in sponge iron 29 in heiß em or cold condition intended. This Chargierschächte 26, 27 is likewise with water-cooled shutoff devices 30 at their inlets into the Ofengefäß 1 provide, whereby the enclosures 30 are gas impermeable the Chargierschächte 26, 27. The sponge iron 29 is delivered over conveyer systems, like chutes or conveyors 31. The Zuschläge and/or coal, coke etc. arrives from Vorratsbunkern of 32 over chutes etc. at the Chargierschächten 26. The interpretation of the Chargierschächte 26, 27, i.e. their number, dimensioning and arrangement takes place as a function of the kind of the Chargierguts. The Chargierschächte 26, 27 is at its lower ends in each case with one against the center of the Ofengefäß it 1 arranged Auslaufschurre 27 ' provide.

In the training of the pits 21, 26, 27 exist groß e variation options. The pits can be trained as “pipe in pipe” - construction (with arbitrary tubing cross sections), whereby the interior pipe forms the preheating pit 21 and the annular space is subdivided around the interior pipe for the formation of several Chargierschächte, e.g. by radially trained partitions. These partitions can be stationarily or mobile, gas-tight or gas permeable. Gemäß another variant could the pits by only one pipe with appropriate interior partitions (e.g. cross-shaped arranged partitions) be formed.

Erfindungsgemäß are from above by cover openings 33 into the inside of the Ofengefäß it 1 rising up, consuming electrodes 34 intended, which are preferably radialsymmetrically arranged. The electrodes 34 are supported over stroke masts 35 and support arms 36 at the foundation 10. They are lowerable and in each case one vertical level, which is preferably radially aligned, at least within an angle of inclination from 0 to 30°, opposite the vertical one tiltable by means of the stroke masts 35 hebund, toward for the center of the Ofengefäß it 1. With melting the brought in steel girders the angle of inclination of the electrodes 34 is usually adjusted to approximately 20 °; it can be differently adjusted and/or regulated for each individual electrode 34. The electrodes 34 can preferably also beyond the vertical one after auß EN against the wall 15 of the Ofengefäß it 1 to be swivelled, around approximately 5 to 10 ° opposite the vertical one.

The Elektrodenwechsel preferentially accomplished in the vertical position of the electrodes 34 with the help of a crane a Elektrodennachnippelung effected at nipple conditions or directly with the electric-arc furnace 3. the number of vewendeten graphite electrodes 34 amounts to preferably two to four or more; at least however a graphite electrode is intended.

For the optimization of the melt guidance are erfindungsgemäß to Einund/or blowing a sauerstoffhältigen gas (CO2 up, air, CO2, H2O etc.) or their mixtures laterally into the Ofengefäß 1 bring inable lances 38 and/or (here not represented) nozzles, if necessary also Unterbaddüsen, intended.

To Einund/or blowing up fine-grained materials (e.g. Carbon and/or steel girders and/or Schlackenbildnern) are intended preferably further injecting lances 39 of different arrangement. These fine-grained materials know also over or several electrode (n) 34, which then as hollow electrode (n) is trained (are), to be brought in. With the help of these fine-grained materials also an early education is made possible for a foamed slag. Further can erfindungsgemäß still auxiliary burners (if necessary as combined jet burners and/or lances) as well as afterburning lances/nozzles for oxygen, air and other oxidizing gases and/or gas mixtures in several places, which can be arranged in different levels, intended its, if necessary also in the scrap iron preheating pit 21. The ground 5 of the Ofengefäß it 1 is zweckmäß industrial union further equipped with ground nozzles and/or - stones 40 for an inert gas flushing (N2, acre).

Erfindungsgemäß it Prozeß expiration with the employment of mixture scrap iron 22 and sponge iron 29 takes place e.g. as follows:

The employment consists of 50% mixture scrap iron 22 (steel girders I) and 50% sponge iron 29 (steel girder II). The chemical composition of these materials used is shown in board 1.

For the execution of the procedure an t-DC-ELECTRICAL-arc furnace 3 (approx. 100 t tap weight, approx. 10 to 15 t remainder sump) serves 100, which is as follows equipped:

• Trafoleistung: 85 MVA;
• 4 Stk. Graphite electrodes 34 (⊘ = 400 mm, within an angle of inclination of 0 upto max. 30 ° in the respective vertical level swing-out), and a ground anode 7.
• A scrap iron preheating pit 21 for preliminary heating and to the Chargieren of the mixture scrap iron 22; with a usable pit height of 5 m and one, concerning this constant, oktogonalen pit cross section (2.9 - 3.0 m clearance) the entire utilizable volume of the scrap iron preheating pit amounts to 21 about 40 m3 and/or its capacity approx. 30 t mixture scrap iron 22.
• 4 Stk. combined Chargierschächte 26, 27 with one, concerning scrap iron preheating pit 21, electrodes 34 and Ofengefäß 1 symmetrical arrangement; Execution of the Chargierschächte 26, 27 as double pits for the separated/independent supply of sponge iron 29 as well as Zuschlägen 28 and/or carbon carriers (e.g. Lime and/or coal /Koksgruß); with a height of the Chargierschächte 26, 27 of 4 m the cross section of the sponge iron Chargierschächte amounts to 27,700 x 700 mm and/or the lime/coal Chargierschächte 26,700 x 300 mm (capacity of the four Chargierschächte 27 approx. 15 t sponge iron 29).
• 2 Stk. Oxygen lances 38 from consuming steel tubes by the side panels 15 of the Ofengefäß it 1.
• 1 Stk. Manipulator for CO2/coal injecting by the cinder door 43.

That erfindungsgemäß e fusion expiration under employment conditions indicated above takes place folgendermaß EN:

After tap of the steel of the preceding load (Fig. 6a) become under leaving a remainder melt 6 first approx. 27 t mixture scrap iron 22, approx. 10 t sponge iron 29, 800 kg lime 28 and 250 kg of coal into the Ofengefäß 1 of the electric-arc furnace 3, on the existing steel sump 6, admitted (Fig. 6b). The Chargieren of the mixture scrap iron 22 takes place via the scrap iron preheating pit 21, whereby the mixture scrap iron 22 was already preheated during the last melt. Anschließ end becomes the scrap iron preheating pit 21 again with the same quantity (approx. 27 t) mixture scrap iron 22 filled. Sponge iron 29, coal and lime are chargiert by the Chargierschächte 26 and 27. As required (e.g. with the furnace start) also mixture scrap iron can do 22, if necessary with sponge iron 29, into that laterally, auß erhalb the cover 19 driven out Ofengefäß 1 over a scrap iron basket or a Schrottmulde to be chargiert.

Afterwards about half of the pouring cone becomes with the help of the electrodes 34 (approx. 20 t) begun of the heap center (electrode position A, angle of inclination of the electrodes 34 15 to 25°) under injecting approx. 250 Nm3O2 and if necessary easy melting of the electrodes 34 melted down, so, daß approx. 3.5 - broad and about 1.0 m of deep fusion craters 41 in the pouring cone develops for 4.0 m (Fig. 6c).

The Erschmelzen of the fusion crater 41 is final after approximately 8 min (with approx. 1 min with 25 MW and approx. 7 min with 65 MW for the supply of the necessary Schnlelzenergie from approx. 7500 to 8000 KW/H).

Those erfindungsgemäß preferential dimensions of the fusion crater 41 are:

• Crater diameter - about 60 - 80% of the inside diameter of the Ofengefäß it 1, so daß in the windnear range a ungeschmolzene, embankment-like layer 42 as warmth (radiation) protection for the brick lining 2 of the wall 15 remains.
• Crater depth - as a function of the furnace interpretation (Größ e and geometry) between 1000 and 1500 mm, under the objective, daß at the ground of the crater 41 a liquid bath (metal and cinder) is present.

Into in such a way trained fusion crater 41 become within the next 11 min under current feed (approx. 65 MW) (electrode position A) approx. 17th sponge iron 29 and approx. 1000 kg lime over the Chargierschächte 26, 27 continuously supplied (Fig. 6d) (the four Chargierschächte 27 for sponge iron 29 are alternating proportioned, emptied e.g. over a cell wheel air-lock, - in each case too secondly - and anschließ end just as filled/emptied). Melting/carbon elimination of the sponge iron 29 in the fusion crater 41 CO2 and approx. 100 kg of fine coal take place for the education from foamed slag under foamed slag and during inert gas ground flushing likewise continuously via injecting altogether approx. 650 Nm3 (by means of two CO2 fresh lances 38 and CO2/coal by means of a manipulator, which is supplied by the cinder door 43).

A part of the developing cinder fließ t by the cinder door 43 out. The exhaust gases are led by the scrap iron preheating pit 21 and for the preliminary heating there in the meantime again of the filled in mixture scrap iron 22 used (Fig. 6d). The average preheating temperature of the mixture scrap iron 22 amounts to approx. 400°C.

After the first continuous addition of sponge iron (2nd sponge iron subset) the electrodes 34 into the electrode position B are raised (power off). Afterwards 41 again approx. 27 t mixture scrap iron 22 (2nd mixture scrap iron portion by the scrap iron preheating pit 21) become, approx. 10 t sponge iron 29 (3rd sponge iron subset by the Chargierschächte 27) into the fusion crater as well as 800 kg lime and 250 kg of coal (over the Chargierschächte 26) admitted (repetition in the Fig. 6b to 6e of represented process steps).

Within the next 8 min becomes in the pouring cone under current feed (begun of the point of the pouring cone) and again CO2 injecting (approx. 250 Nm3 CO2) a fusion crater 41 produces (Fig. 6c), into that anschließ end, like already one describes, the fourth sponge iron subset from approx. 17th under supply of 1000 kg lime over the Chargierschächte 26, 27 within 11 min continuously one chargiert. For carbon elimination and for the foamed slag driving fashion during simultaneous inert gas flushing into the fusion crater 41 approx. 650 Nm3 CO2 as well as approx. 100 kg fine coal over two fresh lances 39 and a manipulator are continuously supplied (Fig. 6d). A part of the cinder fließ t out.

During one anschließ ends flat bath period of approx. 8 min (Fig. 6f and 6g) (also finished melts of the fusion crater, i.e. melting the embankment 42 down within the windnear range of the Ofengefä&szlig, formed by the steel girders; it 1) is finished blown the Metallbad 6 under current feed and inert gas flushing and under addition by 400 kg lime over the Chargierschächte 26 and injecting approx. 400 Nm3 CO2 and approx. 100 kg of coal over the fresh lances 38 and manipulator (also for the education foamed slag) up to the tap and heated at the same time (tap with 0,10% C and 1640°C).

With melting/carbon elimination of the second sponge iron subset as well as during that anschließ ends flat bath period to developed exhaust gases for the preliminary heating of the first mixture scrap iron subset for the next melt is used.

A summary of important operating parameters is shown in board 2.

Erfindungsgemäß the quantitative proportion scrap iron can: Sponge iron in the employment within wide ranges vary; it can be worked also only with scrap iron (100% in the employment).

In principle steel girders I can be chargiert also in more than only one subset before the Chargieren of the steel girders II; likewise it is possible to only chargieren occasionally one for steel girder I containing subset. That erfindungsgemäß e procedure makes in this connection different variations possible, which are selectable in dependence of the quantities of steel girders, the available, I and II.