AU598082B2 - Steelmaking process in oxygen-blown converter - Google Patents

Description

598082 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 Form SUBSTITUTE COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: NAUCHO-PROIZVODSTVENNOE OBIEDINENIE

"TULACHERMET"

Ulitsa Frunze 10 kv. 124, TULA, U.S.S.R.

Anatoly Ivanovich Manokhin; Alexei Grigorievich Zubarev; Gennady Sergeevich Kolganov; Boris Mikhailovich Kostyanoi; Igor Anatolievich Taldykin and Jury Andreevich Rudnev GRIFFITH HASSEL FRAZER 71 YORK STREET SYDNEY NSW 2000

AUSTRALIA

Complete Specification for the invention entitled: STEELMAKING PROCESS IN OXYGEN-BLOWN

CONVERTER

The following statement is a full description of this invention, including the best method of performing it known to me/us:- 0351A:rk I1: _L STEEIAIAKING PROCESS IN OXYGEN-BLOWN CONVERTER The invention relates to metallurgy and has specific reference to a steelmaking process in an oxygen- -blown converter.

The invention may be of utility in making steel in an oxygen-blown converter from ferrous metallic materials in solid form and molten pig iron which are referred hereinafter as charge. These ferrous materials o 10 referred to hereinafter as solid components of the n oO charge can be, for example, scrap, waste iron, crop o-.o ^ends, steelmaking waste, sponge iron and the like.

o°'o The fraction of the solid components of the charge 0o, is limited, being decided by the amount of heat liberated due to the oxidation of the additives introduced into the ferrous melt. This fraction cannot be increased °a 0 unless extra fuel is burnt in the converter for further 0° heating up of the solid components of the charge. The Soo0 more heat is liberated, the higher is the fraction of o o the solid components of the charge, and vice versa.

2 Heating up gives as a rule rise to a liquid phase comprising molten slag and molten metal. Since an appreciable difference exists between the oxidizing potential of the liquid phase thus formed and that of molten pig iron and the reactions taking place are of an explosive nature, ejections of slag and metal are likely to occur when molten pig iron is being poured into the converter.

2 IPig iron is more expensive than solid components of charge and also is in short supply. Therefore, there exists a problem of providing a process of making steel in an oxygen-blown converter from ferrous metallic materials in solid form and molten pig iron which would increase the fraction of solid components in a converter heat and prevent ejections o slag and metal during the pouring of the molten pig iron.

Known in the art is a method of heating up solid components of charge in a converter (SU, A, 960,270).

Sl" This method is realized by providing an oxygenn( -blown converter with tuyeres at the bottom and with a 0 0 tuyere at the top and by admitting a gaseous carbonaceo ous fuel and an oxygen-containing gas through the former and a hydrocarbon fuel and an oxygen-containing gas through the latter.

The known method is effected in the course of the following operations. Solid components of charge loaded into a converter are heated up by burning a gaseous hydrocarbon fuel and a liquid carbonaceous fuel o« admitted through the base and from above, respectively in an atmosphere of an oxygen-containing gas introduced both from above and through the base. The fraction of the oxygen-containing gas fed through the top tuyere amounts to 10-30o of the oxidizer which is theoretically required in order to achieve complete combustion of the liquid fuel admitted through the same tuyere, and the balance of the oxidizing agent is inbro-

I

-3duced through the base tuyeres. On heating up the solid components of charge to a specified temperature, molten pig iron is poured into the converter, the solid components of charge are molten down and the melt is refined by any known technique analogous with the blowing of pig iron.

The known method of heating up the solid components of charge in a converter is conducive to increasing the fraction of solid components in the aggregate mass of the charge loaded into the converter by burning the fuel.

However, the oxygen introduced through the base tuyeres brings about oxidation and fusion of the solid 0 6 components of charge next to the tuyeres with the result that a liquid phase comprising metal and oxidized slag is formed which may give rise to ejections of metal and slag in the course of pouring molten pig iron into the S'3o converter.

Apart from that, a zone of low temperatures (500- 700 C) is set up at the periphery of the solid components of charge, before all close to the base of the converter, because of the hot products of fuel combustion penetrating this zone with difficulty. The solid components of charge heat up therefore nonuniformly so that it is impossible to increase the fraction of solid components in the aggregate mass of the charge by an appreciable amount.

Also known is a steelmaking process which is car- -LII' 'i; ried oat in an oxygen-blown converter equipped with tuyeres at the base and sides (DE, C, 2,816,543). The tuyeres are of the "tube-in-tube" type and serve to admit oxygen over the central bore and liquid or gaseous hydrocarbon fuel through the peripheral clearance. Provision is made for using solid carbonaceous fuel as well.

The known process consists of the following operations. A solid component of charge, for example steelmaking scrap, is loaded into the converter and heated up to 1100 0 C due to the heat obtained from a carbonaceous fuel in gaseous or liquid form admitted in the course of the process in combination with oxygen. On pouring molten pig iron into the converter, the solid com- S° ponent of charge is molten and the ferrous melt so formo 15 ed is refined through the agency of any known technique 0 0 00 0analogous with the blowing of pig iron.

Hot product of fuel combustion pass through the mass of the solid component of charge in the direction o"o from the bottom to the top, heating it satisfactorily 20 *P o, 20 up.

Inherent features of the process are a thermal efficiency which is higher than ever before and speedy heating up of the solid components of charge which takes place owing to a close contact between the hot products of fuel combustion and the solid components of charge. However, their temperature is never above 1100 0

C,

for otherwise the liquid phase may form in significant amounts.

By realizing this method, the solid components of charge are speedely heated up so that their fraction can constitute up to 50% of the charge during a converter heat.

In realizing the process it is, however, evident that a uniform heating up of the solid component of charge remains to be a problem; those solid components which are located at the periphery of the bath and close to its bottom before all heat up to a lesser degree and lag in temperature compared with the solid components at the bath centre. The temperature difference may be as great as the melting point of the so- 0 4)4 on lid components of charge at the bath centre and 500- 0 7000C at the bath periphery w oo 15 Moreover, the oxygen introduced through the base Stuyeres oxidizes and fuses the solid components of charge at their surface in the zone close to the tuyeres, giving rise to liquid phase which is a source S 0 of ejections of metal and slag during the pouring of 20 molten pig iron into the converter.

SThe main object of the invention is to provide a steelmaking process in an oxygen-blown converter using ferrous metallic materials in solid form and molten 44 pig iron which would permit the fraction of the solid components of the charge to be increased and prevent ejections of metal and slag in the course of pokring the molten pig iron into the converter, this object being attained through a more intensive and uniform i -6heating up of the solid components of the charge and control of the heating-up operation.

This object is realized by providing a steelmaking process in an oxygen-blown converter using ferrous metallic materials in solid form and molten pig iron which consists in charging the ferrous metallic materials into the converter, heating them up due to the .ombustion of hydrocarbon and carbonaceous fuels continuously introduced during the process in a stream of an oxygen-containing gas fed from the bottom and top, pouring molten pig iron into the converter and working the heat so as to obtain a given chemical composition wherea in according to the invention the ferrous metallic materials are heated up to a temperature short of the melting point and preparatory to pouring the molten pig iron they are subjected to a homogenizing blast with a neutral gas introduced from the bottom into the stream of the oxygen-containing gas, whereby the amount of the 4 hydrocarbon fuel fed from the bottom is confined to 20 the limit of 1.5-6.0 kg of equivalent fuel per tonne of the ferrous metallic material in solid form.

Realization of the invention creates the prospect of controlling the temperature of heating the solid components of charge. The temperature of the flame set up due to the combustiot' of fuel in the atmosphere of an oxygen-containing gas may vary between 18000 C and 2300°C depending on the type of the fuel and the conditions of its combustion. An increase in the percentr i t S7 age of the neutral gas in the oxygen brings about a reduction in the temperature of the flame and vice versa.

The neutral gas fed into the stream of oxygen may reduce the temperature to 1100-1300 C. As a result the solid components do not melt and no liquid phase is formed in the converter durine the homogenizing blast with either the neutral gas or a dixture thereof with 1 the oxygen-containing components in the presence of natural gas. The melt which has already formed solidifies 10 at this stage.

Apart from that, the volume of the products of combustion increases severalfold when the oxygen is fed in a stream of the neutral gas (apparently due to the f presence of this gas) so that the pressure of these 15 products increases in the lower zone of the solid components of charge loaded into the converter. The neutral i gas fed with the oxygen heats up in the vicinity of the i tuyeres to the ambient temperature, and the hot mixt ture thereof with the products of combustion tends to penetrate all voids and crevices between lumps of the solid components of charge on the way towards the mouth.

The heating-up of the solid components oi charge is not only intensified in this way but it acquires uniformity over the height of the converter and in the transverse.

direction. The homogenizing blast provides for a uniform heating-up of the entire mass of the solid components of charge to a maximum temperature without liquefaction so that there is a practical possibility to r -8

I

0 o 0t~ 0 00 0i 0n 0 0 0 0* 0~ 0* 0 0 00 0* 00 00 0 0 0a rise the fraction of solid components of charge to 60-70% in the convorter heat.

The optimum amount of equivalent fuel introduced,.

through the bottom tuyeres during the homogenizing blast is 1.5-6.0 kg per tonne of the ferrous metallic materials in solid form.

If the fuel is fed in an amount less than the optimum one, the effect of the homogenizing blast is impaired to a point when it exercises no effect on the heating-up of the solid components of charge.

If the fuel is fed in an amount exceeding the optimum one, the homogenizing blast aDpears to be irrational, for an equalization of temperatures occuring in this case which leads to an increase in the losses 15 of heat with the exhaust gases and renders the process economically unattractive. Excessive fuel consumption also brings about excessive cooling of the solid components of charge, impairing the heat balance of the heat.

It is expedient to use nitrogen as the neutral 20 gas, either alone or in combination with oxygen-containing components. Nitrogen is one of the cheapest and abundant neutral gases.

It is also expedient to use the oxygen-containing components in the mixture with the nitrogen in an amount of 50-100% of the quantity required theoretically to achieve complete combustion of the fuel fed from the bottom.

To use the oxygen-containing components in com- 0 00< *41 4 0 i II~ -9bination with the nitrogen in an amount exceeding one which is required theoretically in order to achieve complete combustion of the fuel is impractical, for the excessive oxygen oxidizes the iron of the solid components of charge and leads to an abundant formation of slag with an iron oxide content higher than normal.

Ejections of slag and metal may be' unavoidable in this case during the pouring of the molten pig iron into the converter.

To use the oxygen-containing components in an amount which is less than 50% of the quantity required for complete combustion of the fuel is impractical as well, for the homogenizing blast will be devoid of its effect.

It is further expedient to feed calcium-containing and carbonaceous materials on the surface of the ferrous metallic materials in solid form at a time with the homogenizing blast.

Lime and coal can be used as the calcium-containing and carbonaceous materials, respectively.

A heat-insulating layer of lime and coal prevents high heat losses and contributes to a uniform distribution of the products of combustion over the entire mass of the solid components of charge in the-horizontal direction. At the same time the lime and coal as if passivate the oxidized areas of the charge, the iron oxides being either absorbed by the lime or reduced in the presence of the coal. In other words, the coal and lime facilitate a uniform heating-up of the scrap, render 10 less active the oxidation of the solid components of charge in the course of the heating-up and provide for a reliable prevention of ejections of metal and slag from the converter during the pouring of the molten pig iron thereinto.

It is preferred to tilt the converter with the ferrous metallic materials charged thereinto as far as it will go from time to time simultaneously with the application of the homogenizing blast.

The periodical tilting of the converter improves ;i the contact between the solid and liquid phases of its contents. As the melt flows down the walls of the tilted converter from the places of accumulation, it mixes with lumps of the solid components of charge, giving them up its heat and solidifying owing to that. In addition, ii an averaging of the temperature of the solid components of charge occurs in its bulk. This recommendation is also conducive to an increase in the fraction of the solid components of charge in the converter heat and prevents ejections of metal and slag from the converter while pouring the molten pig iron thereinto.

It is also preferred to tap molten slag from the converter after the homogenizing blast and preparatory to pouring the molten pig iron thereinto. Such approach prevents ejections of metal and slag during the pouring of the molten pig iron.

For a better understanding of the invention a preferred embodiment thereof will now be described by I .I 11 C) a C) 0 C) 0 C) )4 C) o C C) CCC

CC

way of example.

The steelmaking process is embodied in an oxygenblown converter equipped with bottom and side tuyeres of the tube-in-tube type. The central bores of tuyeres are used to feed oxygen and the peripheral clearances serve to introduce hydrocarbon fuel into the converter. The side tuyeres are located either abbve or below the level of metal bath. Provision is made for feeding oxygen via an upper water-cooled tuyere which is adapted for introducing any known type of fuel as well.

The process of making steel from ferrous metallic materials in solid form and jolten pig iron is as follows.

Ferrous metallic materials in solid form and molt- 15 en pig iron are charged into a converter. The disclosed process provides for using scrap, waste iron, crop ends, steelmaking waste, iron-rich pellets, sponge iron and the like as the ferrous metallic materials in solid form for making steel.

The fuel used is commonly of the gaseous hydrocarbon type such as natural gas, methane) propane, butane.

Liquid hydrocarbons such as fuel oil, crude petroleum and diesel fuel can be used ao well.

Alternatively, suitable for use are solid caronaceous fuels, e.g. coke, bituminous coal, brown coal and the like. Not excluded is the possibility of using pulverized coal.

The process of making steel from solid ferrous mac 0'0 0 0 C C J I I L l. i 12 terials, e.g. scrap, and molten pig iron in an oxygen- -blown converter consists in charging the scrap periodically into the converter, heating up the scrap, subjecting it to a homogenizing blast, pouring molten pig iron, melting and refining the melt working the heat so as to obtain a specified chemical composition).

The heating of the scrap is effected by the heat liberated due to the combustion of the hydrocarbon fuel admitted through the side and bottom tuyeres ahd through the water-cooled upper one in a stream of an oxygen-containing gas fed via the same tuyeres. A solid carbonaceous fuel is loaded on the surface of the V C scrap at regular intervals in the course of heating-up.

oe On heating the scrap to a temperature short of e o 15 the melting point the homogenizing blast is applied whereby the consumption of the hydrocarbon fuel fed from the bottom is confined to the limit of 1.5-6.Okg of equivalent fuel per tonne of the scrap.

Oxygen-containing components used as the oxidizer 0 0 are fed in a mixture with nitrogen from the bottom in o an amount of 50-100% of the quantity required theoretically in order to achieve complete combustion of the gaseous fuel fed also from the bottom.

The converter is tilted as far as it will go at regular intervals in the course of the homogenizing blast.

Preparatory to the homogenizing blast an addition of carbonaceous and calcium-containing materials is 13 r? 0 L S3 a 0 ea 0l; 00 r dumped on the surface of the scrap charged into the converter.

After the homogenizing' blast and preparatory to pouring the molten pig iron into the converter, molten slag is being tapped therefrom.

The invention is materialized by effecting control of the heat applied to the scrap.

When the scrap is heated to a temperature short of the melting point but below thereof, liquid phase comprising molten metal and molten slag is formed in a significant amount.

The gaseous reactants referred to above which are added in a specified amount ensure uniform heating-up of the scrap in the bulk and serve to eliminate the li- 15 quid phase formed next to the bottom tuyeres.

When the gases admitted into the converter come into contact with the liquid phase they absorb the heat of the liquid phase and bring about its solidification on the one hand and transfer their heat to the cooler zones of the scrap loaded into the converter on the other hand, facilitating in this way the averaging of the temperature of the scrap in the bulk.

The disclosed process creates the prospect of applying high temperatures for smelting the scrap rithout reservations, for there is no aprehension that a liquid phase may form and give rise to ejections of metal and slag from the converter in this case. This means that the homogenizing blast paves the way to speeding 0 0~ a 4~4 04I o 0u up the heating of the scrap.

All in all, the disclosed process if realized provides for increasing the fraction of the solid components of charge up to 60-70% of the total amount of the charge and prevents ejections of molten components from the converter during the pouring of molten pig iron thereinto.

Example 1 A 10-t converter equipped with bottom and side tuyeres for feeding fuel and oxygen and a water-cooled upper tuy.ere admitted wherethrough was oxygen was charged with 0.70 t of lime and 6.0 t of steelmaking scrap.The up 0o heating of the scrap was effected with natural gas ado3 mitted at a rate of 15-20 m 3 /min via the bottom tuyeres and a rate of 2.5-5.0 m 3 /min through the side tuyeres which were also used to admit oxygen at a rate of 5.10 m 3 /min. Oxygen was also fed over the upper tuyere at a rate varying from 10 m min to 15 m3/min, and after 0,12 min of heating coal dust was charged into the converter in an amount of 0.35 t.

On heating up the charge for 10 min, a homogenizing blast was applied through the bottom tuyeres of the following composition and flow rate: natural gas, 2.34 m3/min;oxygen, 1.63 m3/min; nitrogen, 6.28 m3/min.

The flow rate of the top-fed oxygen remained unchanged.

The homogenizing blast lasted for 2 min, and 4.lt of molten pig iron were charged then into the converter.

During a 30.5-min period of smelting the scrap and converter.

refining the bath a 2.5-min blast of the following composition and flow rate was applied: bottom tuyeres, oxygen at 15-20 m3/min and natural gas at 2.5-5.0 m3/minj side tuyeres, oxygen at 5 m3/min and natural gas at 2 m3/min; upper tuyere, oxygen at 10-15 m3/min. The temperature of the bath after the blast was 1650°C, and the 8.6-t of molten steel were of the following composition: 0.07% C, 0.05% Mn, 0.055% S, the balance being iron.

S 10 Example 2 00 0 O, A 10-t converter was charged with 0.7 t of lime o 0 oo, and 6.1 t of steelmaking scrap, and the charge was heato" ed up, smelted and refined under the same conditions 0 00 0^ o of blasting as in Example. 1. Also 550 kg of coal dust were charged into the converter.

The 5-min homogenizing blast was amitted through the bottom tuyeres at the following flow rates: natural 0 00- o 0° gas, 2.58 m 3 /min; oxygen, 1.66 m 5 /min and nitrogen, o° 0e 6.24 m /min.

On pouring 5.9 t of molten pig iron into the con- 0 verter after the homogenizing blast, the charge was melted and the bath refined during a 28.5-min period.

The total duration of blasting'was 41.5 min, and the bath temperature after the blast was 1625°C. The 8.6-t yield of molten steel was of the following composition: 0.10% C, 0.09% Mn, 0.010% 0.033% S, the balance being iron.

16 Example 3 A 10-t converter was charged with 0.7 t of lime and 5.9 t of steelmaking scrap. On heating the charge up, 350 kg of coal dust, were added thereto. The homogenizing blast was introduced from the bottom at the following flow rates: natural gas, 6.1 m 3 /min; oxygen, 4.27 m3/'min; nitrogen, 16.1 m3/min'. The molten pig iron was poured in an amount of 4.1 t.

The period of melting the charge and refining the bath was 27 min, and the total time of blasting o lasted 40 min. The temperature of the bath at the end o 0 o "o of the blasting was 1640 0 C. The 8.7-t yield of steel was of the following composition: 0.09% C, 0.08% Mn, oro 0.009% P, 0.030% S, the balance being iron.

Complete data about Examples 1 through 3 and those referring to other examples illustrating the disclosed oo method of steelmaking as realized with and without ob- 0oo serving the specified values of process variables are 00O given in Table 1. Table 2 contains comparative data about a process of making steel in a 10-t converter Swithout using homogenizing blast.

The hereinabove provided examples and tabulated data prove the disclosed steelmaking process in an oxygen-blown converter being adapted to work charges containing up to 60-70% of solid ferrous components without a hazard of metal and slag ejections during the pouring of molten pig iron into the converter.

A rise in the percentage of metallic ferrous com- 1=11" 17- Table 1 Effect of Homogenizing Blast on Process Variables 1 Example Ref." Nos. 2 Process vari- 1 2 3 4 ables 0 44 4 0 4 04 90 4 o o 4 4 9 4 044 4 09 44 94 4 4 9 44 94 4 0 44 -Percentage of 3 oxygen consumption (theoretical consumption 100%) Flow rate of hy- 1.0 drocarbon fuel, (0.78) 4 kg of equiv.

fuel (m of natural gas) peir' t of solid component of charge 5 Duration of blast, min 2 6 Flow rate of natural gas,m3/min 2.34 1.5 (1.17) 3 2.38 14 (3.11) (4.66) 3 6.1 4 7.3 5.11 7 Flow Sate of oxygen,m /min 1.63 1.66 6.24 4 44 4 4 4 04 94 4 9 44 0 9 0 9 0 4 44 9 4 0 8 Flow rate of nitrogen, m3/min 9 Solid components of charge,t 10 Molten pig iron charge, t 6.28 6.0 4.1 6.1 4.27 16.1 5.9 4.1 59 8.7 11 Percentage of scrap in charge 59.4 12 Molten steel yield, t 8.6 13 Process efficiency in terms of molten steel,% 85.1 3.9 61.0 8.6 86.0 19.22 6.2 3.8 62 8.9 87.0 89 14 Pig iron pouring Pouring lasted 7-10 min Violent conditions and was accompanied by ejectiejections ons of flame rom converter -18 Table 1 (continued) a .0 040 C.~ o. 01 0 0 00 V0 V 0 Oa Nos.' Example Re Nos.

3 35* 70-1.0 1.0 4.0 6.0 4 (5.44) (0.78) (1.17) (3.11) (4.66) (5.44) 4 2 3 *3 4 4 6' 8.16' 2.42 2.38 6.22 6.87 8.16 7 2.42 2.38-6.22- '6.87 8.16 8- 21.48' 9.10 8.95'-23-40 -25;-84 30.70-- '6,P 62' 6.0 -5.9 -40 3.9 3.8 -4.0 4.1 11-60 61.3 61*'6- 60'0- _59.0O 60*-0 12' 8.8 8.8' 8.9- 9.1 9.0* 90-2- 13 '88 87-12- 89.89 '91.0' 90.0 92'0' 14 Violent ejecti- Pouring without ejections ons of flame from converter -19 Table 1. (continued) 1 11 12 15 14 15 16 2 5 1.5 4.0 6.o 7.0 4 (0.78) (1.17) (5.11) (4.66) (5.44) (0.78) 2 53 5 4 5 2 6 2.42 2.14~ 6.12 7.11 8.16 2.54 U U

'U

0 0 0 U o

U

U U

S

0 ((0

S

'4 55 7 8 9 10 11 15 12 1L3 5.65 13.66 6.2 5.8 62 8.9 89 3. 5.i 15.20 6.0 4.1 59.4 9.0 89.10 9.18 54.55 5.9 4.1 59 9.2 10.,67 40.-,L'4 6.1 5.9 61 9.1 91 12.24 46.05 6.0 4.0 60 9.0 90 4.68 17.60 5.8 61.*2 8.6 87.75 14 Pouring without ejections U OS 0 '4 00 o '4 U 0 '4.3 U U S U U 0 0.3 0 0 TDable 1 (continued) 1 17 18 19 20 21 22 23 24 2 3 100 110 4.0 6.0 7.0 1.0 1..5 4.0 6.0 3 3 4 4 2 3 3 4 4 0 4~ 0 4 4 44 04 4 0 0 4 4 40 44 0 4 4 4 04 44 4 4 04 o 44 0 0 44 0 4o 44 0 ~44 44 44 0 4 t44 04 0 6 2.30 6.32 6.99 7 4.60 12.64 13.98 8 17.50 47.55 52.59 9 5.9 6.1 6.0 15 10 4.2 5.8 4.0 11 58.4 61.6 60 12 8.9 8.6 9.0 20 13 88.12 86.86 90 8.43 16.86 63.43 6.2 3.8.

62 8.9 2.34 5.15 19.37 6.0 4.0 60 8.5 85 2.37 6.12 6.99 8.43 5.21 13.46 15.37 18.55 19.60 50.64 57.82 69.78 6.1 5.9 6.0 6.2 3.9 4.1 4.0 3.8 61 59 60 62 8.8 8.5 8.8 8.4 88 85 88 84 14 Pouring with~out ejec- Pouring 1atted 7-12 min tions because of ejections

U

21- Table 2 Comparative Data of Steelmaking Process Without Resort to Homogenizing Blast 0 0 04 00 4 0 0 C, 00 00 4 0 04 Process variables Example Ref. Nos.

1 2 ~3 '4 Scrap charged, t 5.9 6.2 6.1 6.2 6.2 M~olteni pig iron cbharged,t 4.1 5.8 5.9 3.9 5.8 Percentage of scrap in charge 59 62 61 61.5 62 Molten steel yield,t 8.1 8.2 8.0 8.1 7.9 Process efficiency in terms of molten steel, %o 81 82 81 80.1 79 Pig iron pouring Pouring accompanied by ejections conditions lasted 8-15 min 0 1)4 00 0 4, (41) 0 C~ 01) 0 0 1)1) 0 1) 0 0 0 ~1) 00 4 ponents in solid form in the converter heat reduces first cost of the steel produced.

0 ~0 00 o 00 00 00 0 0 0 0 0 0 004* 00 00 00 0 0 0 0 00 00 4 0 00 0. 00 00 0 0 00 0 00 0 0 0A 00 *4 00 0 0 0 0 0,' 00 0 0 $4

Claims (9)

1. A steelmaking process in an oxygen-blown con- verter using ferrous metallic materials in solid form and molten pig iron which consists in charging the fer- rous metallic materials into the converter, heating them up due to the combustion of hydrocarbon and carbonace- ous fuels continuously introduced during the process in a stream of oxygen-containing gas fed from the bottom and top, pouring the molten pig iron into the converter and working the heat so as to obtain a given chemical compositian thereof, characterized in that the ferrous o metallic materials are heated up to a temperature short of the melting point and are subjected preparatory to pouring the molten pig iron to a homogenizing blast with a neutral gas introduced from the bottom in the stream of the oxygen-containing gas, whereby the amount of the hydrocarbon fuel fed from the bottom is confined to the limit of 1.5-6.0 kg of equivalent fuel per tonne of the ferrous metallic materials in solid form.

2. A steelmaking process in an oxygen-blown con- verter as in claim 1, c h a r a c t e r i z e d i n t h a t the neutral gas used is nitrogen.

3. A steelmaking process in an oxygen-blown con- verter as in claim 2, c h a r a c t e r i z e d i n t h a t the nitrogen is used in the form of a mixture with oxygen-containing components. 24 1

4. A steelmaking process in an oxygen-blown conver- t er asin claim 3, c har a ct er iz ed i n t h a t the amount of the oxygen-containing compo- nents in the mixture with: the nitrogen is 50-100% of the quantity required theoretically to achieve complete com- bustion of the fuel fed from the bottom. U

5. A steelmaking process in 6n oxygen-blown con- I verter as in any of claims c h a r a c t e r i z e d i n t h a t calcium-containing and car- bonaceous materials are fed on the surface of the fer- rous metallic materials in solid form at a time with the homogenizing blast.

6. A steelmaking process in an oxygen-blown con- verter as in claim 5, cii a r a ct e r i z e d i n t h a t the calcium-containing and carbonaceous materials used are lime and coal, respectively.

7. A steelmaking process in an oxygen-blown con- verter as inclaim Ior claim 59 cIia r ac te r i z e d i n t ha t the converter with the ferrous metallic materials charged thereinto is tilted as far as it will go from time to time simultaneously with the application of the homogenizing blast.

8. A steelmaking process in an oxygen-blown con- verter as in any claims 1 through 4, c ha r a ct e- r iz ed i n t ha t a molten slag formed after the application of the homogenizing blast is tapped out from the converter before pouring molten pig iron there into.

9. A steelmaking process substantially as herein descrizbed with reference to any one of Examples to,~ 16. DATED this 23rd day of DECEMBER, 1987 NAUCHNO-PROIZVODSTVENNOE OBIEDINENIE "TULACHERMET" By their Patent Attorneys GRIFFITH HASSEL FRAZER 94 0 00 00 0 00 09 a o 0 00 00 00 00 .4 0 0 0 0 0 0 0