KR20190027552A - Method and installation for producing stainless steel,especially high-quality steel containing chromium ornickel chromium - Google Patents

Abstract

According to the present invention, in a method and an apparatus for directly manufacturing special steel containing stainless steel, chromium, or chromium and nickel from liquid pig iron in which phosphorus is concentrated, a time interval for charging lysate required for a continuous casting device is possible, and a method based on a multiple container system is not required. Moreover, pretreatment to remove phosphorus in an oxygen blowing step is performed in a single container (1; 2), and at the same time, iron slagging, decarburization, and silicon removal are performed by adding a slag forming material and/or a solid cooling material. Slag (19) in which phosphorus is concentrated is taken out, and then, chromium and/or scrap iron, and other alloy elements are charged.

Description

METHOD AND APPARATUS FOR STAINLESS STEEL CONTAINING CHROMIUM ORNICKEL CHROMIUM Technical Field [1]

The present invention relates to a method and an apparatus for producing stainless steel, in particular chromium-containing or chromium-nickel-containing special steel, directly from concentrated liquid iron pig iron.

 Such a type of method is carried out in a dissolution facility comprising one or more vessels, the vessel being operated in either an electric arc mode or an oxygen blowing mode. The steps in such a method are as follows:

(a) charging an alloy carrier with a liquid feed containing iron and / or a solid input,

(b) dissolving the input by arc, (c) refining the melt by blowing oxygen,

(d) reducing the chromium-containing slag. The taped liquid steel is fed directly to the subsequent treatment. Such subsequent processing may consist, for example, of a VOD facility (vacuum decarburization, oxygen decarburization) followed by a continuous casting facility in which the continuous casting installation is supplied with melt via casting lathes.

A method which is carried out in that case is known, for example, from DE 196 21 143 A1. In such a method, the first container of the dissolving process is blown into the charge for decarburization, and at the same time, the second charging is performed in the second container. Such methods reduce the process steps and, above all, reduce the energy consumption in the individual process steps compared to previously applied methods

For example, frequent replacement with complete heat loss is omitted. Further, the working units are formed at a low structural height. In addition, such a method forms the basis for continuously feeding the raw material to a continuous casting machine, which is provided with a new charge for continuous casting after completion of the melting in one vessel,

This is because it can be operated without shortage.

It is an object of the present invention to provide a method for replacing a multi-vessel system or replacing a container of a multi-vessel system with a plurality of charges for a plurality of continuous casting cores, while maintaining the time interval for supplying the melt required for operating the continuous casting facility It is used to dissolve water at the same time.

Such a purpose, which is set in accordance with the present invention, is to carry out a pretreatment for dephosphorization by an oxygen blowing step in a single vessel, and at the same time, adding a slag forming agent and / or a solid coolant to the iron slagging, And the phosphorus is taken out of the concentrated slag, after which it is charged with chromium and / or scrap iron and other alloying elements such as nickel, for example. Thereby, the tapping time is within the interval of the continuous casting facility, and it becomes possible to independently perform the method in each individual vessel or furnace depending on the capacity of the subsequent facility among the individual vessels and the melting facilities having one or more vessels.

It is also important to thoroughly remove the concentrated slag with a residual slag content of less than 30%. Thereby, it is possible to exert a good influence on the phosphorus content in the metal or the steel.

In one construction, 30 to 80% of pig iron is added in addition to the residual input.

Further, the present invention is additionally constituted in such a manner that phosphorus concentrated liquid pig iron is detoxified by blowing oxygen at two or more bath surface points and, at the same time, phosphorus is continuously removed from the concentrated liquid slag. The advantage of doing so is that the process is accelerated and the amount of melt is treated uniformly.

According to yet another step, the phosphorus can be removed quickly and neatly by concentrating the slag through the side container opening and thereby concentrating the phosphorus. Such a container opening is generally already present in the case of an electric arc furnace, and can be provided correspondingly in the case of a converter container.

Another measure is to decontaminate the steel melt with concentrated chromium and / or nickel to less than 1.0% C by oxygen blowing from above or from side while continuously adding solid coolant if necessary.

If the vessel or furnace is equipped with a suitable device, measures may be taken to reduce the slag with a high chromium content by an electric arc with the addition of a reducing agent.

Another alternative to reducing the slag is given by the fact that the slag is eventually reduced to the rest by a perrin-effect with the slag with the slag and / or by strong washing in the ladle.

In an apparatus for producing stainless steel, in particular chromium-containing or chromium-nickel-containing special steels, directly from a phosphorus-enriched liquid pig iron in a melting plant consisting of one, two or more vessels alternately operated by oxygen lance The container wall is provided with a wall opening which can be closed for the side blowing lance, and when the upper blowing lance is provided, the electrode

The above-described method can be advantageously carried out when the system and / or the hoisting and pivoting device for the upper intake lance are provided

In one configuration, measures are taken to provide a unique electrode system in the vessel that can be turned over the vessel. Thereby, the container can be made into an individual converter container.

Another configuration of the vessel is the removal of the slag. In such an arrangement, the container is provided at approximately bath surface height with a wall opening that can be closed for the slag to be taped by tilting the container.

According to another feature, measures are taken to introduce an electrical energy for dissolving the melt and / or overheating and / or reducing the slag, or to provide a logistics system for introducing oxygen via the oxygen intake lance.

In that case, a logistics system that introduces electrical energy for dissolution of the melt and / or overheating and / or reduction of the slag can be done in two containers simultaneously in the case of two vessels, where dissolution and / or overheating and / .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Such a purpose, which is set in accordance with the present invention, is to carry out a pretreatment for dephosphorization by an oxygen blowing step in a single vessel, and at the same time, adding a slag forming agent and / or a solid coolant to the iron slagging, And the phosphorus is taken out of the concentrated slag, after which it is charged with chromium and / or scrap iron and other alloying elements such as nickel, for example. Thereby, the tapping time is within the interval of the continuous casting facility, and it becomes possible to independently perform the method in each individual vessel or furnace depending on the capacity of the subsequent facility among the individual vessels and the melting facilities having one or more vessels.

Figure 1 is a timing chart of method steps that can be done in two independent vessels,
2 is a cross-sectional view of two containers operating in conjunction with one another with a common hoisting and pivoting device for an electrode and a top or bottom lancing lance.

 According to Fig. 1, the melting furnace as the basis of the method described by containers 1 and 2 according to Fig. 2 is formed with an electric arc furnace or a container 1 as a converter and a container 2 spaced from each other, The lifting and pivoting device 11 is provided with arms 12 and 13 for connecting the electrode system 14 and the upper intake lance 15 to the vessel 1 , 2), descending, rising and turning

You can. In the figure, as shown in the drawing, the acceptance lance 15 and the electrode system 14 are in their respective operating intervals

. The container 1 or the container 2 may be formed as a furnace 16 or an injection trough tip and a furnace lid 16a with a protruding window provided with an eccentric tapping tunnel 17. Container 1, 2 or 16 contains a melt 18 with slag 19 on which the process is based. Further, the containers 1, 2 are provided with a floor sink 20. [

Now, referring to Fig. 1, it is possible to produce stainless steels, in particular chromium-containing or chromium-nickel-containing special steels, by means of dissolution (melting 1 and melting 2) which progresses in parallel in succession in the vessel 1 and the vessel 2 Method is shown. The dissolving apparatus shown in Fig. 2 is present at the present moment in the container 1 by means of the electrode system 14 and in the container 2 by means of the upper intake lances 15 and

And / or the lateral blowing lance B, respectively.

In step 1, a solution 1 (indicated as a preliminary dissolution) is initiated by charging the liquid input and / or the solid input in the vessel 2, in which case the phosphorus is introduced into the concentrated iron. Thereafter, in step 2, a slag forming agent such as lime, dolomite and, in some cases, a solid coolant such as scrap iron, sponge iron,

The liquid pig iron is subjected to the removal of the slag 19 by discharging the concentrated slag 19 continuously through the side wall opening 21a to remove the slag. In step 3, the phosphorus is removed from the concentrated slag and finally the slag is removed. As a result, the generation of corrosion resistance of special steel has already begun. For that, in the next step 4 scrap iron, alloy

Iron, and a slag forming agent. In step 5, dissolution and heating are started. For that purpose, the electrode system 14 is pivoted over the vessel 1 for the duration of step 5 and into the operating position as shown. In the next step 6, O 2 blowing is performed by the upper intake lance 15 and the lateral blow lance B to decarburize the steel melt concentrated with chromium and / or chromium nickel

. If necessary, solid coolants such as, for example, FeCr, FeNi, scrap iron, sponge iron and the like are continuously added and the blowing is continued until the carbon content is less than 1.0% C. In step 7, a slag with a high chromium content is reduced under the action of the energy of the electrode system 14 while adding a reducing agent such as FeSi, Al or the like. In step 8,

In which case the reduction of the slag is accomplished during the tap and during the ladle by strong washing through the floor sink.

Loading the pig iron may be done via the trough. In this case, the container wall 21 is provided with a wall opening 21a which can be closed for the side blowing lance B and / or the top blowing lance 15 in Fig. An area of the vessel 1 (2) is provided with a pivotable electrode system 14 and / or a lifting and pivoting device 11 for a top lancing lance 15. A wall opening that can be closed

(21a) has a lifting drive device (23) for lifting the closing plate (24). The refractory lining 26 is provided with a graphite beam 25 at the tapping edge so that the slag flows out when the container 1 (2) is slightly inclined on the pivot bearing 27. The tapping of the liquid steel can be accomplished through the bottom out spout 28 in the overhang 30 as is conventional. The graphite beam 25 is a

And is disposed in alignment with the bath surface height 29. The wall opening 21a is located in the wall of the furnace lid 16a.

Between the vessels 1 and 2 a distribution system 22 for introducing electrical energy for dissolving and / or overheating the melt 18 and / or for reducing the slag 19 or for introducing oxygen via an oxygen- (See Fig. 1), such a logistics system 22 is provided in which the dissolution and / or superheat and / or reduction is not effected simultaneously in the two vessels 1, 2,

So that it can be supplied via the oxygen intake lance only.

Thus, the method in the vessel 1 begins with step 5 (dissolving and heating), followed by step 6 (blowing O 2 by the top inlet lance and side inlet lance) followed by step 7 ), And step 8 (tapping with liquid steel slag), and a new time interval, step 1 (phosphorus-enriched liquid iron

And the electrode system 14 is required in the vessel 2 at the end of the process. At this time, in the vessel 1, step 2 is carried out to detoxify the liquid pig iron by the O 2 blowing lance . Thereby, it is ruled out that the dissolution in the two vessels is prevented from interfering with each other, which is controlled by the distribution system 22.

1 container 1 2 container 2
11 Lifting and turning device 12 Arm
13 Arm 14 Electrode System
15 Blowing Lance 16 No
16a No cover 17 Eccentric tapping
18 Lysine 19 Slag
20 floor sink 21 container wall
21a Lateral wall opening 22 Logistics system
23 lifting drive device 24 closing plate
25 graphite beam 26 fireproof lining
27 Pivot bearing 28 Floor spout
29 Bath surface height 30 Overhang

Claims (1)

A method for producing stainless steel, particularly chromium-containing or chromium-nickel-containing special steel directly from phosphorus-enriched liquid pig iron, comprising the steps of pretreating in a single vessel by an oxygen blowing step and simultaneously carrying out a slag forming agent and / Adding a solid coolant to perform iron slagging, decarburization, and demixing to remove the phosphorus-enriched slag, and thereafter removing chromium and / or scrap
Wherein the method comprises charging iron and other alloying elements from the concentrated liquid iron.

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