JPH0246648B2 - SANSOTENROCHUDENOHAGANENOYOKAIHO - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION This invention relates to metallurgy, and more particularly to a process for melting steel in an oxygen converter. The present invention can be used to produce steel from solid metallic iron-containing materials in oxygen converters. Such solid metallic iron-containing material (metal charge material) can be, for example, scrap, off-cut ends, metal waste from steel mills, as well as metallized pellets, sponge iron, and the like. PRIOR ART Methods for producing steel in oxygen converters using solid metal charges are known in the art (DE, C,
2719981, DE, C, 2729982, DE, C,
2729983). To produce steel by such a method,
Oxygen converters are equipped with "pipe-in-pipe" type bottom and side tuyeres. Oxygen is injected through the central passages of these tuyeres, and liquid or gaseous hydrocarbon fuel is supplied through the outer passages. Load the converter with solid metal charge. This charge is first heated due to combustion of a hydrocarbon fuel (gaseous or liquid) in an oxygen-containing gas that is injected into the converter from the bottom and side through the tuyere (blow-in ). As it is heated, the solid metal charge melts. Milled carbon-containing materials (e.g. coke, coal, graphite or mixtures thereof) carry additional energy when the charge melts near the tuyere (a steel bath is formed). It is loaded into the converter as a body. The supply of carbon-containing fuel is gradually reduced to an extent that protects the tuyere from destruction, ie to 8-12% (by volume) of the oxygen consumption. When the solid metal charge is completely melted, the steel bath is smelted by any method known in the art similar to iron blowing. Heating of the bath is accomplished primarily by the heat released by the oxidation reaction of carbon dissolved in the iron. At the same time, milled lime is also charged into the bath with oxygen for the formation of slag. When the metal reaches the required temperature, it is tapped from the converter. The steelmaking technology described above makes it possible to use available carbon-containing materials such as coke, coal, graphite and mixtures thereof. However, for their preparation and transfer to the converter,
Additional equipment has to be installed, which results in increased capital investment. During the melting process, the oxygen moving through the liquid metal near the tuyere is partially consumed to oxidize the iron, which results in an increase in the amount of slag and the ferrous oxide (FeO) content in the slag. This will result in an increase. The ferrous oxide forms a slightly fused eutectic with the refractory lining material, which increases lining wear. "Process for the production of steel in oxygen converters" is also known in the art (International Application PCT/SU83/00025, April 17, 1984). The process is carried out in an oxygen converter, which is equipped with bottom and side tuyeres of the "tube-in-tube" type. Oxygen is injected through the central passage of the tuyere, and liquid and gaseous hydrocarbons are injected through the outer holes. The possibility of oxygen injection through the upper water-cooled lance is also provided. The method includes the following technical process: loading solid metal charge material (for example metal scrap) and then, during the process, continuously charging hydrocarbon and solid carbon-containing fuel into the tuyere. heating and melting by combustion in oxygen-containing gas which is injected into the converter from the bottom, top and side through. The carbonized iron melt is then refined. The hot combustion products moving from the bottom to the top heat the solid metal charge loaded into the converter. During the heating process of the solid metal charge, oxygen-enriched air is injected through the bottom tuyere to burn the fuel. At the same time, pure oxygen is injected through the upper lance and side tuyere. Then, in the melting and refining process of iron carbide melt, the consumption of oxygen in the oxygen-containing gas injected through the bottom tuyere is increased to 100%. This method, which is based on varying the amount of oxygen in the oxygen-containing gas, provides uniform heating and subsequent complete melting of the solid metal charge. However, blowing the melt with oxygen-containing gas during the heating of the solid metal charge and its melting results in the formation of a significant amount of slag with higher ferrous oxide (FeO) content. will be done. This results from the oxidation of iron and the iron oxides as rust are placed in a steel bath along with the iron-containing material. The ferrous oxide forms a fusible eutectic with the refractory lining material, which melts thereby causing wear of the lining. In addition, smelting iron carbide melts under slag with high ferrous oxide (FeO) content can also cause slopping of metal and slag from the converter, which increases the duration of the process. Adversely affect. The object of the present invention is to provide a method for melting steel from solid metallic iron-containing materials in an oxygen converter, which reduces the duration of the melting process and reduces the wear and tear of the converter lining. An object of the present invention is to provide a method that makes it possible to reduce. (Means for Solving the Problems) It is an object of the present invention to charge a solid metallic iron-containing material and then roll the successively charged hydrocarbon and solid carbon-containing fuel from below, above and from the side. The present invention relates to a process for melting steel from solid metallic iron-containing material in an oxygen converter, which comprises heating to form a melt by combustion in an oxygen-containing gas fed into the furnace. Accordingly, the melt is 1525~
Oxidizing slag is removed from the surface of the melt when the temperature is 1580°C, after which iron is charged into the melt in an amount of 2 to 5% of the initial amount of the metallic iron-containing material. This is accomplished by providing a method for melting steel in the medium. Implementation of the invention allows adjustment of the melt temperature regime and the slag regime. It offers the possibility of shortening the duration of the melting process, ie the possibility of heating the steel bath more quickly. This is due to a higher degree of after-combustion of carbon monoxide. Under the condition that there is no liquid iron in the metal charge, the degree of carbon monoxide after-combustion in the converter exhaust gas increases with increasing ferrous oxide content in the slag. The increase in the ferrous oxide content in the slag during the process of melting the charge material as well as at the initial stage of heating the steel bath when the temperature of the steel bath is in the range of 1525-1580 °C is due to the increase in ferrous oxide content in the slag. Facilitates an increase in the degree of carbon afterburning. The carbon monoxide burns off on the steel bath and considerably accelerates the melting of the charge and the heating of the melt, thereby shortening the duration of the melting process. However, as the temperature of the melt increases above 1580° C., a higher degree of oxidation of the slag has a negative effect on the resistance of the lining. Because 1580
This is because at temperatures above 0.degree. C., ferrous oxide forms a slightly melting eutectic with the refractory lining material, the melting of which causes rapid wear of the refractory lining of the converter. For this reason, it is necessary to remove oxidizing slag from the surface of the melt at temperatures below 1580 °C. Removal of slag from the surface of the melt is possible at temperatures above 1525 ° C. This is because for this purpose it is necessary to completely melt the charge material, which has a melting point of about 1525°C. At temperatures below 1525 ° C, it is impossible to remove oxidizing slag from the melt surface. Practical conditions for complete melting of the charge material require heating the charge material relative to its melting point. Even after removing the oxidizing slag from the surface of the melt, a small amount of this slag is still present in the steel bath. In order to deoxidize the slag remaining in the melt, it is necessary to feed it with deoxidizing substances. In the present invention, solid iron is used as deoxidizer in an amount of 2 to 5% by weight of the metal charge. The need to use solid iron allows carbon from the solid iron to directly enter the melt and react with the slag, thereby reducing the ferrous oxide content remaining in the slag, and that is also required as an essential condition by the fact that it reduces the wear of the refractory lining of the converter at elevated temperatures. The effect occurs due to the highly developed interaction surfaces of both reactive phases, ie metal and slag. In addition, the carbon from the solid iron directly enters the melt and acts as an additional energy carrier, and this results in a shorter duration of the melting process. Substituting any other carbon-containing material (eg, coal) for iron is less effective in this context. This is because the reaction between the slag bath and the solid material occurs at a very slow rate due to the low diffusion rate and is additionally accompanied by foaming of the slag. For the reasons mentioned above, it is necessary to add iron to minimize oxidation of the slag. When using a solid metal charge, solid iron is added in an amount of 5% of the total amount of the metal charge;
Reduce the total content of ferrous oxide (FeO) in slag to 15~
20%, which provides a slag with satisfactory refining capacity and which reduces the amount of slag during subsequent charging of coal or any other carbon-containing material into the converter. Sufficient to prevent foaming. Taking into account the above-mentioned influence of solid additives on the oxidation of the slag, it is undesirable to add solid additives in amounts exceeding 5%. This is undesirable since adding more iron increases the carbon content in the metal considerably, which in turn increases the duration of the melting process. If solid iron is added in an amount less than 2%, the ferrous oxide content cannot be reduced to 20%,
That is why the lower limit for the amount of solid iron additive is 2% of the initial amount of metal charge. After charging the solid iron into the melt, it is desirable to add the solid carbon-containing fuel into the melt in an amount of 1 to 5% of the original amount of solid metallic iron-containing material. Such addition makes it possible to accelerate the heating process of the steel bath due to the burning of carbon from the carbon-containing material on the surface of the steel bath, which as a result further increases the duration of the melting process. shorten. In addition, this fuel acts as a deoxidizer for the oxidizing slag still remaining in the steel bath, as the carbon in the fuel reduces iron from ferrous oxide, which results in as a reduction in wear and tear on the refractory lining of the converter. The consumption of solid carbon-containing fuel (for example coal) which is additionally charged into the converter according to the invention is governed by a value of 1 to 5%. The exact value of the additive depends on the temperature of the melt after removal of the oxidizing slag, as well as on the required temperature at the end of the melting process, ie on the required temperature rise. The temperature is 1580℃
When the temperature rises from 1600 to 1610℃, 1% of coal is required, and when the temperature rises from 1580℃ to 1640 to 1650℃, 2% coal is required.
% coal is required, from 1580℃ to 1680-1700℃
5% coal is required. DESCRIPTION OF THE PREFERRED EMBODIMENTS In order that the invention may be better understood, the following specific examples are presented below. The process of the invention is carried out in an oxygen converter with bottom and side tuyeres of the "tube-in-tube" type. Oxygen is injected through the central passages of these tuyeres and hydrocarbon fuel is supplied through their outer passages. The converter is also equipped to inject oxygen through an upper water-cooled lance. A process for producing steel from solid metallic iron-containing materials (eg, metal scrap) includes: The following materials can be used as solid metallic iron-containing materials for steelmaking according to the method of the invention:
Scraps, scraped ends, metal waste from steel factories, metallized pellets, sponge iron, etc. Gaseous hydrocarbons as fuel (e.g. natural gas,
Preferably, liquid hydrocarbons (eg residual oil, petroleum, diesel fuel) are used. Also, as a fuel, solid carbon-containing fuel (e.g. coke, coal, charcoal, etc.)
can be used. The process for producing steel from solid metallic iron-containing materials in an oxygen converter consists of a period of loading the charge into the converter, a period of heating the charge, a period of melting the charge,
Includes a period of slag removal from the steel bath and a subsequent oxidation refining period. The heating of the solid charge and its melting results in the combustion of hydrocarbon fuel fed through the bottom and side tuyeres in an oxygen-containing gas injected through the same tuyeres and through the top water-cooled lance. This is done using the heat released. During the heating and melting period, solid ferrous material is periodically loaded onto the metal charge to maintain combustion of the solid carbon-containing fuel. The proportion of oxygen in the oxygen-containing gas injected through the bottom tuyere when the heating time of the charge material reaches the melting period of the charge material is 20~
Increase from 70% to about 100%. During the melting and heating of the charge, pure oxygen is injected through the side tuyeres and the upper water-cooled lance. The charging material is melted and its temperature is 1525 ~
At 1580°C, oxidizing slag containing 30-70% ferrous oxide (FeO) is removed from the surface of the steel bath. After removing the oxidizing slag from the surface of the steel bath, solid iron and additional coal are continuously fed into the steel bath in amounts of 2-5% and 1.5% of the total metal scrap material, respectively, and then the melt is Refine. Refining of the carbonaceous iron melt is carried out by any method known in the art. That is, during the refining process, the ratio between the amount of oxygen and the amount of hydrocarbons fed through the bottom tuyere is adjusted in such a way that the hydrocarbons do not serve as fuel, but serve as a protective medium for the oxygen lance. Ru. Refining the steel to the desired chemical purity and temperature. The invention is based on adjusting the temperature and slag conditions. Melt blowing is difficult, on the one hand, when the slag is highly oxidized (FeO = 30-70%) during the melting period of the charge material and in the early stages of heating the melt, but when the temperature of the steel bath is 1525-1580 °C When it is not higher than that, it helps to increase the degree of carbon monoxide after-combustion. In the converter, carbon monoxide burns above the steel bath, which considerably helps to speed up the melting of the metal charge and the heating process of the steel bath, which makes it possible to shorten the duration of the melting. Make it. In this period, the oxidation of the slag acts positively, so the more slag there is in the converter and the higher its content of ferrous oxide, the more the after-burning of carbon monoxide. The process becomes even stronger. In addition, with increasing melt temperature, it is necessary to reduce the degree of oxidation of the slag. That is, it is necessary to shorten the duration of the interaction between the ferrous oxide present in the oxidizing slag and the refractory lining of the converter, thereby reducing wear on the converter lining. be. The problem with reducing the degree of slag oxidation can be solved by removing the slag from the surface of the steel bath and then by adding solid iron and a supplementary amount of solid carbon-containing fuel to deoxidize the steel bath. It will be resolved. Implementation of the present invention reduces the duration of the melting process by about 10% and the wear of the converter lining by about 30-35%.
% reduction. Example 1 Lime was placed in a 10 t converter with bottom and side tuyeres for fuel and oxygen and water-cooled lances for top oxygen.
Loaded with 0.5t and 10t of metal scrap. The scrap was heated by enriched air containing 50% oxygen and 5-8 m ³ /min of natural gas injected through the bottom tuyere. Oxygen is supplied through the side tuyere at a rate of 5 to 10 m ³ /
injected at a volume of min. The consumption of oxygen injected through the upper lance was varied within the range of 10-15 m ³ /min. Melting of the charge material was carried out in the same manner as its heating. That is, the consumption of the gas components fed into the converter during the melting process was the same as for heating. In addition, oxygen instead of enriched air through the bottom tuyere
It was injected at a rate of 10-15 m ³ /min. During heating and melting, 400Kg of coal was charged into the converter in 100Kg portions. When the charge was melted, the slag contained 30% ferrous oxide and 4% magnesium oxide. The solid charge dissolved in 30.5 minutes. The temperature was 1525°C. An amount of 0.5 t of oxidized slag was removed from the converter (pumped out).
After starting blowing again (through the bottom tuyere 15-20
Inject m ³ /min oxygen and 2.5-3.0 m ³ /min natural gas, inject 5 m ³ /min oxygen and 2 m ³ /min natural gas through the side tuyere, and inject 10-15 m ³ through the upper lance. /min of oxygen injected), solid iron
200Kg and 500Kg of small grain coal were continuously charged into the converter. Blowing continued for another 7 minutes. The net total blowing time was 37.5 minutes. At the end of blowing, the temperature of the metal was 1630°C. The composition of the metal is:
0.07% C; 0.02% Mn;. 008% P; 0.035%
S, the rest was iron. The ferrous oxide content in the final slag was 16.8% and the magnesium oxide content was 3.9%. Example 2 A 10 ton converter was loaded with 0.5 ton of lime and 9.9 ton of metal scrap. The blowing conditions were the same as in Example 1. During the heating and melting of scrap, coal dust
450Kg was loaded into the converter. When the charge material melted (32 minutes), the total ferrous oxide content in the slag was 49.2% and the magnesium oxide content was 4.3
It was %. The temperature of the steel bath was 1580°C. 550Kg of slag was pumped out of the converter and 350Kg of solid iron was charged into the converter. Additionally, during blowing (6 minutes), 100 kg of coal dust was charged into the converter. Before tapping, its composition is: 0.04% C,
It was 0.03% Mn, 0.010% P, 0.027% S, and the balance was iron. The ferrous oxide content in the final slag is
18.3% and magnesium oxide content is 4.2%
It was hot. The metal temperature was 1650°C. Example 3 A converter was loaded with 0.5t of lime and 9.6t of metal scrap. During heating and melting, 300Kg of coal dust was loaded into the converter. When the charge material has melted (31 minutes),
The total ferrous oxide content in the slag was 36.7%, and the magnesium oxide content was 4.5%.
The temperature of the steel bath was 1550°C. 500Kg of slag was pumped out of the converter and 300Kg of solid iron was charged into the converter. During the subsequent blowing (6.5 minutes), 300 kg of coal dust was charged into the converter. Before tapping, its composition is: 0.05% C, 0.02%
It consisted of Mn, 0.008% P, 0.033% S, and the balance iron. The ferrous oxide content in the final slag is 15.1%
The magnesium oxide content was 4.5%. The metal temperature was 1650°C. Examples 1, 2, 3 and other examples specifying the invention within and beyond the applicable parameters (Example 4)
The data for ~6) are shown in the attached table. Data specifying the production of steel from solid metal charges in a 10 ton converter using methods known in the prior art are also presented for comparison.

[Table] Mass, kg

The above comparison shows that the present invention makes it possible to shorten the duration of heating and melting of the solid metal charge and to shorten the total blowing time by about 4 minutes. The wear and tear of the refractory lining is reduced by 30-35%. The use of the method of the invention therefore makes it possible to shorten the melting duration and reduce the wear of the refractory lining by regulating the slag formation and using deoxidizing substances.

Claims (1)

[Claims] 1. Charge a solid metallic iron-containing material, then successively charge hydrocarbons and solid carbon-containing fuel into the converter from the bottom, top and side. A process for melting steel from solid metallic iron-containing materials in an oxygen converter comprising heating to the formation of a melt by combustion in a gas, the temperature of said melt being between 1525 and 1580°C. Sometimes, the oxidizing slag is removed from the surface of the melt, after which solid iron is charged into the steel bath in an amount of 2 to 5% of the initial amount of the solid metallic iron-containing material. Method of melting steel in a converter. 2. after introducing the solid iron into the melt, an additional amount of solid carbon-containing fuel is charged into the melt in an amount of 1 to 5% of the initial amount of the solid metallic iron-containing material, A dissolution method according to claim 1.