EP0030360A2 - Steel-making process - Google Patents

Abstract

Oxygen is introduced onto the surface of a molten ferrous metal through at least one water-cooled lance disposed above the melt surface while an oxygen free gas in which is entrained ground solids is intermittently introduced into the molten ferrous metal through tuyeres disposed below the melt surface.

Description

The invention relates to a method for producing steel in a converter, which is equipped with nozzles below the steel bath surface, based on the converter blowing position and a water-cooled lance and / or inflation nozzles in the upper region of the converter lining.

Oxygen freshening for steel production by means of the inflation process and the blow-through process with nozzles made of two concentric pipes for the oxygen and a protective medium arranged in the refractory lining, for example in the converter floor, are used in steel plants worldwide. The further development today aims to increase profitability by improving the spreading rate, reducing the amount of additives (slag formers) and media (oxygen and coolant). Another development direction is to increase the scrap rate to the exclusive use of scrap and to supply the required energy in the form of fuels with the highest possible thermal efficiency to the melt.

Proposed solutions for this have recently become known. In one of these processes, the scrap is first preheated in the converter, and then carbon-containing, powdered fuels are passed into the melt for further energy supply.

In some, methods of increasing the scrap rate oxygen is blown through the bath and 20 to 80% of the total amount of oxygen as a free jet onto the melt. It is also known to subject the carbon monoxide leaving the melt to post-combustion above the melt.

In another method for producing steel in the converter, heat is supplied to the melt by carbon-containing fuels. The carbon-containing fuels are introduced into the melt, while the oxygen for freshening the melt and for burning the fuels is introduced into the converter simultaneously with gas jets directed onto the bath surface and below the bath surface. The particular advantage of this process is that the fuels introduced are burned to carbon dioxide with a high thermal efficiency of about 30%, based on the combustion. The high level of energy utilization is achieved by supplying oxygen to the bath surface and the associated supply of heat from the CO afterburning to the melt.

The known method also allows the number of nozzles below the bath surface to be reduced; this is associated with further advantages in steel production. A disadvantage of the known method is, however, that if the blowing rate of the carbon-containing fuels is greatly increased under certain operating conditions, there are limits to the simultaneous supply of fuel and oxygen due to the limited blowing cross section of the few nozzles below the bath surface.

In the oxygen inflation process without fresh gas supply below the surface of the bath, the deterioration of the fresh effect at low carbon contents is known as a disadvantage. With a carbon content of the melt of, for example, ≤ 0.1%, the decarburization rate decreases significantly, since the decreasing CO bubble formation no longer leads to a concentration equalization in the melt. At the same time, the iron oxide content in the melt increases. The decreasing decarburization rate leads to an extension of the freshening time and the increased iron oxide content in the slag acts as a loss. Both the extension of the fresh time and the reduction in spreading have an unfavorable effect on economy.

According to the current state of the art, the oxygen blowing process, which does not have these disadvantages, requires at least one change of soil during the operating time of a converter lining. The refractory material in the area of the oxygen nozzles in the converter base wears out at about twice the speed compared to the lining of the converter side wall. In addition to the cost of the refractory material, the working time of around 20 hours for changing the floor is lost as production time.

The above-mentioned methods contain partial solutions for the disadvantages of the oxygen inflation and oxygen blow-through method and show how the heat available during steel production in the converter can be increased. Injecting oxygen below and above the bath surface into the melt, in addition to the disadvantages of the complex installation for the devices of the oxygen supply below and above Melt, for certain steel qualities undesirably high hydrogen and nitrogen contents from the nozzle protection medium of the oxygen nozzles below the bath surface. Furthermore, during decarburization, there is a weaker dephosphorization compared to the oxygen inflation process.

It is therefore the object of the invention to combine the advantages of a special slag guide, similar to the oxygen blowing process, but without increased iron losses in the slag, and the advantages of the oxygen blowing process, in particular with regard to the low final carbon contents with a lower iron oxide content of the slag connect as well as to achieve low hydrogen and nitrogen contents in the steel. In addition, the aim is to achieve a high thermal efficiency when blowing carbon-containing fuels into the melt and to improve the durability of the refractory lining in the area of the nozzles (converter floor) below the bath surface.

After all, even with only a few nozzles in the converter base, it should be possible to blow in relatively large amounts of carbon-containing fuels.

The above-mentioned object is achieved in that the oxygen is added according to the invention by means of a water-cooled lance and / or at least one inflating nozzle directed onto the bath surface in the upper converter lining on the bath surface, and in that solids are ground by the double tube nozzles operated with a protective medium below the bath surface Formation of slag and / or at least for the supply of heat be introduced into the melt in a suspension with an oxygen-free gas.

Surprisingly, it has been shown that when blowing in oxygen-free gases below the bath surface, to which the ground solids are temporarily charged to form slag and with which carbon-containing pulverized fuels, for example coke, are introduced into the melt, are sufficient to produce steel in the converter perform with favorable results, as are known from the oxygen blowing process. In particular, easily controllable, low carbon contents can be set in the slag without higher iron losses. For example, carbon levels of 0.03% could be achieved with iron oxide levels in the slag of approximately 12%. In the oxygen inflation process, the iron oxide content of the slag is already around 25% when the carbon in the steel is still around 0.05%.

According to the invention, less than half of the nozzles normally required in the oxygen blowing process are installed in the converter bottom and / or the lower side wall below the bath surface. Usually these are the usual nozzles consisting of two concentric tubes. In special cases, however, ring slot nozzles according to German patent 24 38 142 can also be used, or nozzles made from three concentric tubes are used. These three-tube nozzles have two ring gaps of approximately the same size, approximately Q5 to 2 mm wide. The three-pipe nozzle guides the suspension of solids and inert gas in the central tube, which is the central tube-surrounding annular gap the oxygen and the outer annular gap hydrocarbons in the melt. The amount of hydrocarbon used to protect the nozzle is low and is normally 0.1 to 5%, based on the amount of carrier gas in the central tube. The proportion of oxygen in the annular gap corresponds at least to the amount of hydrocarbon. During the last fresh phase, inert gas, for example argon, or another nitrogen- and hydrogen-free gas can also be introduced through all three nozzle channels.

The bath is to be understood as the converter volume that the completely fresh, resting steel melt occupies when the converter is in the blowing position. The bath surface is accordingly the surface of this melt.

If scrap is preheated in the converter, e.g. in the production of a molten steel from solid iron carriers, the nozzles in the steel bath area serve as oil / oxygen burners for preheating scrap. As soon as there is melt in the converter, these nozzles are used to introduce carbonaceous fuels and slag formers.

• In der Entsilizierungsphase, d.h. ungefähr in den ersten 1 bis 2 Minuten der Frischzeit, dienen die Düsen zum Zuführen der Schlackenbildner, vorzugsweise Kalk. Während des Hauptfrischens, etwa den sich anschließenden 5 bis 10 Minuten, wird durch diese Düsen die erforderliche Menge kohlenstoffhaltiger Brennstoffe, beispielsweise pulverisierter Koks oder Kohle eingeleitet. Dazu kann parallel weiterer Kalk eingeleitet werden. Zum Beispiel können zwei Düsen der Kohlenstaubförderung und eine oder mehrere Düsen gleichzeitig zum Einleiten von Schlackenbildnern dienen.

In the method according to the invention, the nozzles below the bath surface are used approximately according to the following scheme:

• In the desiliconization phase, ie approximately in the first 1 to 2 minutes of the fresh time, the nozzles serve to supply the slag formers, preferably lime. During the main refresh, such as the following 5 to 10 minutes, these nozzles supply the required amount carbon-containing fuels, for example powdered coke or coal. Additional lime can be introduced in parallel. For example, two coal dust extraction nozzles and one or more nozzles can be used to introduce slag formers at the same time.

In the finished fresh phase, for example in the last two to five minutes, the nozzles below the bath surface are preferably only used to introduce hydrogen- or nitrogen-free gases with or without loading with slag formers.

Hydrocarbons, such as natural gas, methane, propane or heating oil, have proven themselves as nozzle protection media to prevent the nozzles from burning back prematurely in the converter lining. Argon, carbon monoxide and carbon dioxide are preferably used for finishing or post-blowing for steel grades with low hydrogen and nitrogen requirements.

In the method according to the invention, oxygen can preferably be blown continuously or briefly through the central tubes of the nozzles in the bath area until after blowing. This measure primarily serves to clear the nozzle pipes of unwanted blockages and approaches at the nozzle mouth and to set the desired mushroom-like approaches at the nozzle mouth in the desired size (diameter approx. 100 mm). The alternate operation with slag-forming carrier gas, fuel suspensions and oxygen is possible with the corresponding changeover valves. The one below the Badober The amount of oxygen blown in is small and less than 20% of the total amount of oxygen.

It is also within the scope of the invention to extend the supply of the small amount of oxygen until the post-blowing phase and in special cases also during post-blowing in the described three-tube nozzle, in which the central suspension medium tube is surrounded by an oxygen ring gap and a second ring gap for hydrocarbons. The amounts of oxygen that are passed through are also small when the three-tube nozzle is operated continuously and amount to a total of about 10% of the total amount of oxygen.

According to the invention, the oxygen for blowing the melt, for afterburning the reaction gases from the melt and for burning the carbon-containing fuels in the melt is blown onto the bath surface. A water-cooled oxygen lance has proven itself for this if oxygen is blown onto the bathroom surface as a free jet via one or more nozzles in the upper converter side wall. The distribution of the amount of oxygen between the lance and inflation nozzles can vary within wide limits. However, at least 1/4 of the oxygen, based on the total amount of oxygen, is passed through the side wall nozzles, as long as the lance blows in the area of the slag bath at a distance of approx. 0.2 to 1.5 m.

The use of the oxygen lance allows active slag work practically from the beginning of the freshening, probably because the slag is hotter than the molten iron itself, in which scrap still dissolves. The Slag formers, mainly lime, possibly with the addition of fluorspar and / or dolomite, are partly charged into the converter as lump lime or charged to the oxygen of the blowing lance and / or the side wall nozzle in the form of dust lime. Usually about half of the lime requirement is added to the bath surface; the rest is fed through the nozzles below the bath surface. However, the ratio can be shifted up to about 3/4 in either direction. Preferably about 10 to 20% of the total amount of lime is charged into the converter as lump lime. This results in viscous slags prior to tapping, which are easier to hold back in the converter, and the safe return of phosphorus and sulfur from the slag to the steel melt before tapping is avoided.

This addition technique according to the invention of the slag formers, in particular the lime, below and above the bath surface brings about an early dephosphorization and an improved desulfurization of the iron melt. The mode of action is probably such that the overheated slag on the bath surface and the blown-in oxygen advance the dephosphorization to the actual decarburization phase and the lime powder blown through the melt at relatively high carbon contents, i.e. low oxygen potential of the melt, which leads to intensive desulfurization. In the last fresh minutes of the finished fresh period, the melt is supplied with lime through the floor nozzles.

According to the invention, the lance distance in the main blowing phase can be increased approximately after half the fresh time. It is in the spirit of the invention, the lances Increase the distance as far as possible, ie about 1.50 m above the surface of the bath, so that the oxygen jet has a similar effect to the free jet of the side wall nozzle and contributes to CO post-combustion and return of the heat generated to the melt.

According to the invention, it is possible without principle disadvantages to remove the lance from the converter after about half the fresh time and to only blow the oxygen onto the bath via one or more side wall nozzles.

In special cases, especially if water-cooled lances can no longer be installed when converting existing oxygen blow-through converters to the method according to the invention, it proves to be possible to work without an oxygen lance and to install oxygen inflation nozzles in the converter lining at two different levels above the bath surface. The lower installation level of the side wall nozzles then lies between approx. 0.5 and 2 m above the bath surface. The nozzles are also directed towards the bath surface. In this lower installation level, one or more side wall nozzles can preferably be arranged above the converter pivot, based on the converter blowing position. The nozzles take over the described function of the water-cooled lance in the first half of the fresh season. The position of one or more nozzles in a second, higher level of the converter side wall corresponds in function to the side wall nozzles described when using a water-cooled inflation lance.

Another variant of the method according to the invention makes it possible to work only with a water-cooled lance above the bath surface without side wall nozzles. The lance is then only at the beginning of the fresh water during the desiliconization phase at the aforementioned short distance from the bath surface. Then, about 2 minutes after the start of freshness, as soon as the decarburization phase begins or carbon-containing fuels are added to the melt, the lance distance is increased to over 1.50 m, preferably over 2 m, above the bath surface. In this mode of operation, it has been shown that the oxygen jet emerging from the lance opening has a sufficient running distance in the converter space above the melt in order to ensure optimal afterburning of the reaction gas leaving the melt and return of the heat obtained to the melt. Although this procedure somewhat limits the flexibility of the lance guidance in relation to the fresh flow in comparison to the combination of lance / side nozzles, the advantages of the method according to the invention could also be achieved with this mode of operation. There have been no disadvantages with regard to iron slagging and the high thermal efficiency of the fuels which contain carbon dioxide and are passed into the melt.

In order to be able to introduce large amounts of fuel into the melt per unit of time, even if the number of nozzles below the bath surface is only small, the oxygen below the bath surface can be introduced into the melt only temporarily according to the invention. The high efficiency in the supply of energy by blowing carbon-containing fuels is also then reached when oxygen is only temporarily led into the melt below the bath surface. Obviously, the temporary induction is sufficient to create conditions that favor the retransfer of the energy obtained from the afterburning of the exhaust gases in the upper converter room to the bathroom. It has been shown that, during certain fresh phases, it is possible to use all the nozzles below the bath surface to introduce the carbon-containing fuels as a suspension with an oxygen-free carrier gas. Surprisingly, it is possible to dispense with oxygen blowing in below the bath surface for up to half of the total fresh time without any disadvantages for the thermal efficiency of the carbon-containing fuels.

The specified total time, during which no oxygen is introduced below the surface of the bath, can be divided into several, shorter periods of time and be continuous.

Another feature of the invention is to introduce the slag formers, preferably lime (Ca0) in powder form through the nozzles below the bath surface. The preferred method of addition is to charge the powdered lime with oxygen.

The invention is explained in more detail below with the aid of non-restrictive examples and an illustration which shows a section through a converter.

A converter for the inventive method consists of a sheet steel jacket 1 with a refractory walling 2 and a removable bottom 3, are 4angeordnet in its refractory lining Düs _E n. The nozzles 4 are usually the known OBM nozzles made of two concentric tubes. Some or all of these floor nozzles can also be designed as three-tube nozzles.

In the converter shown, for example, two bottom nozzles 4 are arranged for introducing the dried and pulverized carbon-containing fuels. The suspension of fuel, e.g. Lignite coke powder with an oxygen-free carrier gas, e.g. Nitrogen or argon flows through a manifold 5 via a T-shaped distribution piece 6 to the switching valves 7 and from there to the central tubes of the nozzles 4. The switching valves 7 allow the central tubes of the nozzles 4 to be alternately filled with a fuel inert gas suspension or to be supplied only with an oxygen-free gas, in special cases also oxygen, which flows via a line 8 to the changeover valves 7. The annular gaps of the nozzles 4 are supplied with either a liquid or a gaseous protective medium. The change from liquid to gaseous media and vice versa takes place with the aid of pressure-controlled switching valves 9, which are usually integrated in a nozzle connecting flange 10. The liquids and gases are supplied to the changeover valve 9 via feed lines 11, 12.

The floor nozzles 4 work, for example, for preheating solid iron supports as burners. Then liquid hydrocarbons, for example light heating oil, flow through line 11, via switchover valve 9 into the nozzle ring gap and through line 8 via switchover valve 7 Oxygen in stoichiometric amount for the oil combustion through the central tube of the nozzle 4. As soon as there is melt in the converter and covers the nozzle orifices, the powdered fuel supply is switched over and at the same time the annular gaps of the nozzles 4 are filled with gaseous protective media, for example hydrocarbons such as natural gas or Propane, supplied. The melt can consist of molten steel or post-charged pig iron.

The other floor nozzles are constructed in principle in the same way and serve to supply oxygen-free gases, to which powdered slag formers, in particular Ca0 and / or carbon-containing fuels, are charged as required. However, all floor nozzles can only be fed with a suspension of carbon-containing fuel and an oxygen-free gas.

The floor nozzles for the introduction of the slag formers, only one of which is shown, are evenly charged with the gas-Ca0 suspension via a collecting line and a lime distributor (not shown). Gaseous hydrocarbons have proven to be reliable as a protective medium in the annular gap, in particular when oxygen or oxygen-containing gases flow briefly through the central tubes of the nozzles. During the preheating of the solid feed materials in the converter, the nozzles are operated as burners.

An oxygen nozzle 14, ie an inflation nozzle or side wall nozzle, is located in the lining 2 of the converter 1 above one of the converter pivot pins 13. This inflation nozzle 14 preferably consists of two concentric Pipes, the oxygen also flowing through the central tube and a nozzle protection medium through the annular gap. The outlet opening of the nozzle 14 on the inside of the converter lining 2 is at least 2 m above the bath surface 15. In the case shown, this installation height is approximately 3 m. At least 1/4 of the total amount of oxygen flows through the side wall nozzle. The oxygen jet emerges from the nozzle opening at approximately the speed of sound and acts as a free jet in the gas space of the converter. It sucks a multiple of its volume of the reaction gases escaping from the melt in the converter space above the melt. A significant proportion of the carbon monoxide of these reaction gases, experience has shown that at least 2096, is subsequently burned to C0 ₂ . The heat generated is almost completely transferred to the melt in the operating mode described, and there is no overheating of the upper converter lining. The heat radiation from the free jet, which is at a high temperature (estimated at approx. 2800 ° C), is apparently absorbed by the gases in the converter room that are contaminated with dust, slag and steel droplets.

Further oxygen is blown onto the bath surface by means of the water-cooled oxygen lance 16. In this case, it is a lance with four outlet openings. In the illustrated mode of operation with a lance and side nozzle, the lance is controlled in such a way that it moves close to the bath surface 15 at the start of freshness and the lance distance is increased with increasing freshness. When the amounts of oxygen are divided between the side nozzle and the lance, at least 25% of the total amount flows through the side nozzle, but preferably 30 to 50%.

If all of the oxygen is only blown up by the water-cooled lance, the lance distance from the bath surface 15 should be at least 1.50 m after the start of blowing, but at the latest after the desilication phase.

When an oxygen-free gas is fed through the nozzles 4 below the bath surface with at least temporary loading of pulverized solids, it is possible to maintain a sufficient bath movement, even against fresheners, at very low carbon contents, in order to generate foam slag as in the case of the oxygen blowing process , and to avoid a sharp increase in the iron oxide content of the slag. Roughly 10 to 20% of the amount of oxygen as an oxygen-free gas below the bath surface is sufficient as a rough orientation value.

A 60 t converter of the type shown in the drawing had an internal volume of 55 m ³ in the newly bricked-up state. Five nozzles were arranged in the floor on an approx. 50 cm wide median strip, parallel to the axis of rotation of the converter. Two of these nozzles consisted of three concentric tubes, the central tube having a clear diameter of 30 mm and the two annular gaps each having a width of 1 mm. These two nozzles were used to supply pulverized carbonaceous fuels. The three other nozzles below the bath surface consisted of two concentric tubes with a clear central tube diameter of 30 mm and an annular gap width of 1 mm. These nozzles were used to supply oxygen-free gases with and without loading with slag formers and or carbonaceous fuels. Approx. 27 t of solid iron carriers, in particular scrap of mixed quality, and occasionally portions of solid pig iron were placed in the converter and pre-reduced iron ores, charged.

The solid starting materials were preheated in other experiments in such a manner that all five nozzles operated as burner and flows through the annular gaps fuel oil in an amount of 100 1 per minute and through the central pipes required for the stoichiometric combustion oxygen amount of 200 Nm ³ / min. This resulted in preheating times of 1 to 10 minutes.

After the batch charging, 40 tons of liquid pig iron with a temperature of 1300 ° C. and a composition of 4.2% carbon, 0.7% silicon, 0.6% manganese, 0.35% phosphorus and 0.035% sulfur were charged without preheating . Immediately after the converter had been erected into the blowing position, approximately 18,000 Nm ³ / h of oxygen flowed through two side wall nozzles, which were arranged approx. 3 m above the bath surface in the converter lining above the pivot. The position of the side nozzles was such that the gas jets hit approximately the center of the bath surface. With the two floor nozzles for the fuel supply, 20 Nm ³ nitrogen / min flowed through the central tube, loaded with 300 kg lignite coke powder per minute. At the same time, 10 Nm ^{3 of} oxygen / min flowed through the inner annular gap and 1 Nm ^{3 of} propane / min through the outer annular gap. The other three floor nozzles were supplied with a total of 40 Nm ³ / min nitrogen in the central tube and 1.5 Nm ³ / min propane in the annular gap. Instead of nitrogen, C0, C0 ₂ and inert gases such as argon have also proven their worth. The nitrogen in the central tube was charged with approx. 3 t of dust lime for slag formation in the first blowing phase, during which the carbon-containing fuels were added. The time for this Fresh phase was about 10 minutes.

After this first fresh phase, in which the carbon content of the melt was still approximately 1.5 to 2%, the fuel supply was stopped. The central tubes of the nozzles below the bath surface were then supplied with argon in an amount of 70 Nm ³ / min. After a further approx. 5 minutes, the converter was switched over for sampling. This was followed by a two-minute correction blow in which the nozzles below the bath surface in the central tube and in the annular gap were supplied with argon. Instead of argon, CO, CO ₂ and mixtures of these gases with argon have also proven their worth. Approximately 1 ton of lime (Ca0) was charged into the converter during the corrective blowing. After a total fresh time of 17 minutes, the finished steel melt with a composition of 0.03% carbon, 0.1% manganese, 0.020% phosphorus and 0.015% sulfur was tapped. The tapping temperature was 1650 ° C and the batch weight was 61 t.

A 200 t converter, which worked according to the method according to the invention, had a water-cooled oxygen lance and two side wall nozzles in the converter hat. During the freshness period of approx. 12 minutes, approx. 7000 Nm ³ were caused by the oxygen lance as when inflating oxygen

Oxygen and approx. 3000 Nm ³ oxygen blown through the two side wall nozzles onto the bath surface. There were eight nozzles for oxygen-free gas below the surface of the bath. During the first approx. 8 blowing minutes, a total of approx. 1000 Nm ³ nitrogen flowed through the nozzles below the bath surface, loaded with a total of 10 t of dust lime for slag formation and 5 t of coke flour to increase scrap by 10 percentage points.

Through the annular gap of the nozzles were during the ge 40 Nm ^{3 of} natural gas. In the last four blowing minutes, 500 Nm ³ argon was introduced into the melt via the nozzles below the bath surface. Without taking into account the additional melted scrap from the fuel supply (coke flour), the scrap rate could be increased by 6 t, corresponding to 3 percentage points, compared to the oxygen inflation process. Output was also improved by 1.5%. This is mainly due to the low iron oxide content of the slag of approx. 15% compared to 25% in the oxygen inflation process and a lower iron loss in the exhaust gas of approx. 0.5% compared to 1.2% in the inflation process.

Similarly advantageous values could be set in the same 200 t converter if all the oxygen was passed through the water-cooled lance and the nozzles below the bath surface were only operated with a suspension of an oxygen-free carrier gas and slag formers or carbon-containing fuels. However, compared to the usual oxygen inflation process, the lance distance (distance of the lance opening from the bath surface) was increased shortly after the start of blowing, about 1 minute later, to about 1.50 m and after another minute to about 2 m.

A significant advantage of the method according to the invention has been the improvement in soil durability compared to the oxygen blowing method. With the usual floor lining of approx. 1 m thickness, there was no need to change the floor for each converter lining. The improvement is very likely Soil durability can be attributed to the lower number of nozzles compared to the oxygen blowing process and the use of oxygen-free gases.

The essential feature of using oxygen-free gas below the bath surface with and without loading solids (slag formers and / or carbon-containing fuels), for example, in an amount of up to approx. 20% of the total oxygen or in small or continuous amounts of oxygen, but not more than 10% of the Total oxygen supply has a number of advantages.

Claims (11)

1. A method for producing steel in a converter which is equipped with nozzles below the bath surface and a water-cooled lance and / or inflation nozzles above the bath surface, characterized in that the oxygen supply is directed through a water-cooled lance and / or at least one onto the bath surface Inflation nozzle takes place on the bath surface and is loaded into the melt through the nozzles below the bath surface at least temporarily only an oxygen-free gas, at least partially with ground solids for slag formation and / or for the supply of heat. 2. The method according to claim 1, characterized in that the entire oxygen for freshly melting the melt, for afterburning the reaction gases from the melt and for burning the carbon-containing fuels in the melt, is blown onto the bath surface. 3. The method according to claim 1 or 2, characterized in that slag formers such as Ca0, dolomite, fluorspar, calcium carbide or mixtures thereof are introduced through the nozzles below the bath surface. 4. The method according to one or more of claims 1 to 3, characterized in that carbon-containing, pulverized fuels, such as coal, coke, coke breeze, lignite coke, graphite and mixtures thereof, in suspension with an oxygen-free carrier gas through the nozzles below the bath surface be introduced into the melt. 5. The method according to one or more of claims 1 to 4, characterized in that as oxygen-free carrier gases for the introduced below the bath surface, ground solids nitrogen, carbon dioxide, carbon monoxide, natural gas, methane, propane, inert gases, e.g. Argon and mixtures thereof. 6. The method according to one or more of claims 1 to 5, characterized in that at times oxygen or an oxygen-containing gas is blown into the melt below the bath surface. 7. The method according to one or more of claims 1 to 6, characterized in that below the bath surface oxygen-containing gases or oxygen, but in total less than 20% of the total amount of oxygen, are used. 8. The method according to one or more of claims 1 to 7 ,. characterized in that slag formers are charged as lump in the converter or blown in the form of dust lime on the bathroom surface. 9. The method according to one or more of claims 1 to 8, characterized in that the oxygen is blown onto the bath surface only with a water-cooled lance and the distance between the lance opening and the bath surface after the desiliconization phase is at least 1.5 m. 10. The method according to one or more of claims 1 to 9, characterized in that the oxygen supply to the bath surface takes place through one or more nozzles which are installed in the converter lining and are protected with a protective medium against premature burning back, and that from the The gas jet emerging from the nozzle opening acts as a free jet for a considerable distance and sucks reaction gases out of the converter space before it hits the bath surface in the converter. 11. The method according to one or more of claims 1 to 10, characterized in that with simultaneous supply of oxygen through a water-cooled lance and one or more blow nozzles directed to the bath surface, at least a quarter of the total amount of oxygen is passed through the blow nozzles.

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