US2802731A

US2802731A - Process of producing bessemer steel

Info

Publication number: US2802731A
Application number: US400383A
Authority: US
Inventors: Heimberg Karl; Lanzendoerfer Erich
Original assignee: Cie Generale Des Conduites D E
Current assignee: Cie Generale Des Conduites D E; GENERALE DES CONDUITES D'EAU Cie
Priority date: 1950-08-14
Filing date: 1953-12-24
Publication date: 1957-08-13
Anticipated expiration: 1974-08-13
Also published as: NL82672C; FR1039133A; GB709999A; CH291268A

Description

United States Patent 2,802,731 PROCESS OF PRODUCING BESSEMER STEEL Application December 24, 1953, Serial No. 409,383

Claims priority, application Germany August 14, 1950 1 Claims- ((11. 1 -4 No Drawing.

The present invention relates to a process of producing Bessemer steel and more particularly to a process of treating iron-containing material in a cupola furnace in such manner that the resulting molten iron is directly suitable for a treatment in a Bessemer furnace for the production of Bessemer steel in a rapid and economical manner.

The present application is a continuation-in-part of our co-pending application Serial No. 239,858, filed August 1, 1951, now abandoned for Process for Ohtaining a Pig Iron Suitable for the Bessemer Process.

According to the known methods, the calories for the production of steel in a Bessemer converter were supplied by the so-called chemical means, namely the combustion of silicon and manganese in the iron. It was therefore necessary for the production of Bessemer steel to first prepare a special Bessemer iron charge containing high quantities of manganese and silicon.

The combustion of the manganese and silicon in the Bessemer furnace supply the calories for the production of the Bessemer steel. In order to produce the special iron for use in the Bessemer furnace, it was necessary to treat an iron charge in a blast furnace in such manner that the resulting pig iron is chemically hot, namely it contains high quantities of silicon (about 2%) high quantities of carbon (about 4%) and high quantities of manganese (about 1.2%). Thus, the production of Bessemer steel was very expensive since it involved loss of these elements by theoxidation thereof.

An additional disadvantage of the known processes for the P o i n of Be se er ste is the f ct th t special means had to be utilized for the removal of impurities such as sulfur and phosphorus from the iron. This special treatment for the removal of sulfur and phosphorus had to be employed before the iron was subjected to treatment in the Bessemer furnace otherwise the resulting Bessemer steel would have high quantitiesof sulfur and phosphorous which adversely affects the properties of the steel.

The only way the special treatment for the removal of sulfur and phosphor-us from the iron prior to treatment of the iron in the Bessemer furnace could be avoided was to utilize as starting material in the blast furnace a raw material which was substantially free of sulfur and phosphorus, since blast furnace treatment could not remove the sulfur and phosphorous. However, such sulfurand phosphorous-free raw material is relatively expensive and thereby additionally added to the cost of the Bessemer steel. a 7

Thus, starting from ordinary raw material, the ordinary production of Bessemer steel involves four basic treatments:

-l. treatment of the raw material in a blast furnace,

2,802,731 Patented Aug. 13, 1957 adding silicon and iron to produce a Bessemer pig iron rich in silicon and manganese; 1

2. re-treatment in a cupola for a preliminary refining, namely the elimination before Bessemer treatment of a portion of the impurities such as. sulfur and phosphor? ous;

3. heating in an intermediate mixer between the cupola and the converter in order to re-heat the pig iron and give to it the desired composition; and

4. treatment in an'acid Bessemerfurnace by burning the silicon and manganese to supply calories for'the treat:

ment.

It is therefore an object of the present invention L provide a process for producing Bessemer steel whereby the number of separate treatments is reduced and the process is greatly simplified.

It is another object of. the present invention to provide a process of producing Bessemer steel without the necessity of first producing a special Bessemer pig iron rich in silicon and manganese.

It is still another object of the present invention to provide a process of producing Bessemer steel whereby the raw material is in a single treatment directly suitable for treatment in the Bessemer furnace.

A further object of the present invention comprises the utilization of any iron-containing material a iaw material without the necessity of enriching the raw ma: terial in silicon and manganese.

Still another object o the present invention is the attainment of great economy in the production of Bessemer steel while obtaining a Bessemer steel of supfi 'ior quality to that produced by known processes. 1

Other objects and advantages of the present invention will be apparent from the further reading of the specification and of the appended claims. 1

With the above Objects in view, the present invention mainly comprises a process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace an iron containing material also-containing impurities with an excess of 'carbon, pas in into the thus charged cupolafurnace a heated fluid containing y e a a m ture sufiicienfly h to Q ain by Oxidation of h c rbon i t arge a e pe atu of at least 1500 C. in the cupola furnace while maintaining a reducing atmosphere therein due to the excess of carbon, thereby melting the iron-containing material containing impurities in a reducing atmosphere in the .c'upola furnace while preventing formation of iron oxides, passing the molten iron-containing material in the ,cupola furnace through a molten basic slag at a temperature of at least 1500" C. so as to remove impurities from the molten iron-containing material and form substantially pure molten iron being at a temperatureof at least 1500 C., and subjecting the molten iron while still at a temperature of at least 15 00" C. to treatment in a Bessemer furnace, the temperature of at least 1500" C. supplying the calories for the treatment in the Bessemer furriace, thereby rapidly forming a high quality Bessemer stee According to the present invention the molten .iron leaving the cupola furnace is sufliciently free .of impurities, due to the reducing atmosphere and basic slag at the high temperature in the cupola furnace, to be directly treated in the Bessemer furnace for conversion .to Bessemer steel. In addition, due to the high temperature of at least i)" 0 at which the molten iron is taken from the cupola furnace, the mo ten iron can be directly treated in the Bessemer furnace, since the temperature of 3 1500, C. is sufficient to supply all the calories necessary for the Bessemer treatment. It is therefore unnecessary, according to the present invention, to add silicon and manganese to the original charge in the cupola furnace in order to produce a pig iron which is rich in silicon and manganese.

In addition to the economy of saving silicon and manganese, this high temperature of themolten metal leaving the cupola furnace which permits Bessemer conversion without supplying chemical heat by the burning of silicon and manganese, is of advantage in that there is no possibility for the resulting- Bessemer steel to contain silica which has adverse effects on the properties of steel.

' It is therefore possible to produce Bessemer steel by means of the intermediate treatment in the cupola furnace according to the present invention starting from any raw material without the necessity of having silicon and manganese and without'the necessity of choosing raw materials which are free of impurities such as sulfur and phosphorous.

The amount of carbon in the charge is in excess of the amount normally used for fusion processes and is in sufiicient excess to produce a reducing atmosphere in the cupola furnace. The term excess of carbon is therefore meant to comprehend within its meaning an amount of carbon which in proportion to the amount of air or the like oxidizing agent introduced into the cupola furnace is in such excess that a reducing atmosphere will be formed. In other words, either the carbon will not be completely oxidized to carbon dioxide, or carbon dioxide which is formed is reduced by the excess carbon to carbon monoxide.

The desired high temperature is obtained despite incomplete combustion of the carbon by the utilization of a hot blast. Preferably air, or air enriched with oxygen, is pre-heated to a temperature of about 400600 C. before being introduced into the cupola furnace.

The reducing atmosphere in addition to causing reduction of the iron oxides to iron, is of advantage in maintaining a basic slag which is necessary for the removal of the impurities such as sulfur and phosphorous from the iron. If necessary, basic materials such as limestone or the like may be added to the charge to be certain that a basic slag is formed.

Although, according to the present invention, it is possible to do away completely with the addition of silicon and manganese to the charge, it is possible to add these compounds to the charge in small amounts. In such case, because of the reducing atmosphere and the basic slag and the high temperature, only very little of the silicon and manganese is lost in the slag and practically the whole is incorporated into the molten pig iron.

Although the cupola furnace may have an acid lining, it is preferred to utilize a neutral lining and most preferably a basic lining. A basic melting can be obtained in a cupola cooled at the level of the melting zones even where the lining of the furnace is neutral or acid, since the furnace is charged, not only with coke and iron materials but also with lime, dolomite or other basic materials in suflicient quantities to effect a basic melting in the cupola.

An additional advantage of the process of the present invention is the fact that the blowing period in the Bessemer converter is much shorter than when utilizing an ordinary Bessemer pigiron. This is due to the fact that the calories are supplied mainly by the high temperature of the molten iron which is charged into the Bessemer converter. In the ordinary Bessemer process the duration of blowing is about 1618 minutes. According to the present invention this blowing period is shortened by at least When considering large quantity production, this saving of time in addition to the possibility of utilizing cheaper raw materials, the saving of silicon and manganese and the saving of steps, is of great advantage.

The Bessemer pig iron which is generally charged to a Bessemer converter according to theknown processes Percent C 4-4.5 Si 1-1.8 Mn 0 7 P 0.080 l S 0.05 According to the present invention, on the other hand, the carbon, silicon and manganese content of the pig iron charged into the Bessemer converter may be greatly reduced, i. e., to 0.3% silicon, 0.5% manganese and 2.7% carbon.

' The following examples are given as illustrative of the present invention and are not to be construed as limiting the scope thereof: s

Example 1 A cupola furnace is charged with iron turnings and 20% coke, by weight. The iron turnings contain the following elements in the amounts given:

. Percent Si 2.35 Mn 0.56 P Q 0.84 S 0.08

Air, pre-heated at a temperature of about 500 C., is blown into the cupola, a reducing atmosphere being formed due to the excess of carbon, to produce a working temperature of about 1530 C. The slag is maintained basic by the addition of lime if necessary, and the molten pig iron which is withdrawn from the cupola at a temperature of about 1530 C. has the following composition:

Percent Si 0.3 Mn 0.5

P 0.05 S 0.06 C 2.7

This pig iron is immediately charged into Bessemer converter and subjected to a hot blast for about 15 minutes to produce a Bessemer steel having high qualities, particularly due to the extremely low silica content of the steel.

Example 2 A cupola furnace is charged with 83% of a pig iron having a high sulfur and high phosphorous content and having approximately the following composition:

Percent Si 1.55 Mn 0.32 P 1.92 S 0.72 C 3.26

with approximately 17% coke and with a small amount of calcium oxide to assure a basic slag. The charge is treated as in Example 1 utilizing a blast of air heated at a temperature of about 600 C., the temperature of the slag being about 1600 C. The resulting molten iron has approximately the following composition:

Percent Si 0.2 Mn 0.3 P 0.09 S 0.06 C 2.4

This molten iron is directly charged into a Bessemer converter and treated therein to produce a high quality Bessemer steel.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims. p

What is claimed as new and desired to be secured by Letters Patent is:

1. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace an iron-containing material also containing impurities with an excess of carbon; passing into the thus charged cupola furnace a heated fluid containing free oxygen at a temperature suflicientlyhigh to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing at mosphere therein due to said excess of carbon, thereby melting said iron-containing material containing impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to remove impurities from said molten iron-containing material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

2. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace an iron-containing material also containing impurities with an excess of carbon; passing into the thus charged cupola furnace a fluid containing free oxygen and being at a temperature of about 400-600 C. so as to obtain by oxida tion of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to remove impurities from said molten iron-containing material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapid, ly forming a high quality Bessemer steel.

3. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace a charge being substantially free of silicon and mangan-ese and including an iron-containing material also containing impurities with an excess of carbon; passing into the thus charged cupola furnace a heated fluid containing free oxygen at a temperature sufliciently high to obtain by oxidation of the carbon in the charge a temperature of, at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing impurities in a reducing atmosphere in said cupolafurnace while preventing formation of iron oxides; passing said molten iron-containing material in said-cupola furnace through a molten basic slag at a temperature of at ,least 1500 C. .so as to remove impurities from said molten iron-containing material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

4. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace an iron-containing material also containing sulfur and phosphorous as impurities with an excess of carbon; passing into the thus charged cupola furnace a heated fluid containing free oxygen at a temperature sufliciently high to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing sulfur and phosphorous as impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to desulfurize and dephosphorize said molten ironcontaining material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

5. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola having a neutral lining a charge being substantially free of silicon and manganese and including an iron-containing material also containing sulfur and phosphorous as impurities with an excess of carbon; passing into the thus charged cupola furnace a heated fluid containing free oxygen at a temperature sufficiently high to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing sulfur and phosphorous as impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to desulfurize and dephosphorize said molten ironcontaining material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

6. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace having a basic lining a charge being substantially free of silicon and manganese and including an ironcontaining material also containing sulfur and phosphorous as impurities with a excess of carbon; passing into the thus charged cupola furnace a heated fluid .c0ntaining free oxygen at a temperature sufliciently high to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing sulfur and phosphorous as impurities in a reducing atmosphere in said cupola furnace While preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag ,at a temperature of at least 1500 C. so as to desulfurize and dephosphorize said molten ironcontaining material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel. 7. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace an iron-containing material also containing impurities with an excess of carbon; passing into the thus charged cupola furnace heated air enriched with oxygen and being at a temperature of about 400-600 C. so as to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing impurities in a reducing atmos phere in said cupola furnace while preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to remove impurities from said molten iron-containing material and and form substantially pure molten iron being ata temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

8. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace an iron-containing material also containing impurities with an excess of carbon and a quantity of basic materials sufiicient to form a basic slag; passing into the thus charged cupola furnace a heated fluid containing free oxygen at a temperature sufficiently high to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten iron-containing material in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to remove impurities from said molten iron-containing material and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

9. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace iron ore also containing impurities with an excess of carbon; passing into the thus charged cupola furnace a heated fluid containing free oxygen at a temperature sufficiently high to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said iron-containing material containing impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten iron ore in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to remove impurities from said molten iron ore and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

10. A process of producing high quality Bessemer steel, comprising the steps of introducing into a cupola furnace scrap iron also containing impurities with an excess of carbon; passing into the thus charged cupola furnace a heated fluid containing free oxygen at .a temperature sufficiently high to obtain by oxidation of the carbon in the charge a temperature of at least 1500 C. in said cupola furnace while maintaining a reducing atmosphere therein due to said excess of carbon, thereby melting said scrap iron containing impurities in a reducing atmosphere in said cupola furnace while preventing formation of iron oxides; passing said molten scrap iron in said cupola furnace through a molten basic slag at a temperature of at least 1500 C. so as to remove impurities from said molten scrap iron and form substantially pure molten iron being at a temperature of at least 1500 C.; and subjecting said molten iron while still at a temperature of at least 1500 C. to treatment in a Bessemer furnace, said temperature of at least 1500 C. supplying the calories for said treatment in said Bessemer furnace, thereby rapidly forming a high quality Bessemer steel.

11. A process of obtaining a pig iron suitable for charging a Bessemer converter which comprises charging a cupola with a charge consisting essentially of an iron containing material and an excess of carbon suflicient to form in said cupola a reducing atmosphere, subjecting said charge to a'hot blast of about 400600- C. and heating said charge to at least 1500 C. until a molten pig iron containing a maximum of 0.3% silicon and 0.5% manganese is formed, and recovering said molten pig iron having a minimum working temperature of about 1500 C. and containing said amounts of silicon and manganese. i

12. A process of obtaining a pig iron suitable for charging a Bessemer converter which comprises charging a cupola with a charge consisting essentially of an iron scrap and an excess of carbon sufiicient'to form in said cupola a reducing atmosphere, subjecting said charge to a hot blast of about'400600 C. and heating said charge to at least 1500 C. until a molten pig iron containing a maximum of 0.3% silicon and 0.5% manganese is formed, and recovering said molten pig iron having a minimum working temperature of about 1500 C. and containing said amounts of silicon and manganese.

13. A process of obtaining a pig iron suitable for charging a Bessemer converter which comprises charging a cupola with a charge consisting essentially of an iron containing material and 17-20% coke sufficient to form in said cupola a reducing atmosphere, subjecting said charge to a hot blast of about 400-600 C. and heating said charge to at least 1500 C. until a molten pig iron containing a maximum of 0.3% silicon and 0.5 manganese is formed, and recovering said molten pig iron having a minimum working temperature of about 1500 C. and containing said amounts of silicon and manganese.

14. A process of obtaining a pig iron suitable for charging a Bessemer converter which comprises charging a cupola with a charge consisting essentially of an iron ore and an excess of carbon sufficient to form in said cupola a reducing atmosphere, subjecting said charge to a hot blast of about 400600 C. andheating said charge to at least 1500 C. until a molten pig iron containing a maximum of 0.3% silicon and 0.5% manganese is formed, and recovering said molten pig iron having aminimum working temperature of about 1500 C. and containing said amounts of silicon and manganeses.

15. A process of obtaining a pig iron which comprises charging a cupola with a charge consisting essentially of an iron containing material consisting at least partly of scrap iron and an excess of carbon suflicient to form in said cupola a reducing atmosphere, subjecting said charge to a hot blast of about 400-600" C. and heating said charge to at'least 1500 C. until a molten pig iron 9 a 10 containing a maximum of 0.3% silicon and 0.5% man- References Cited in the file of this patent ganese is formed, and recovering said molten pig iron UNITED STATES PATENTS having a minimum working temperature of about 1500 C. and containing said amounts of silicon .and manga- 2669446 Doat 1954 nese. 6 OTHER REFERENCES Manufacture of iron and steel, vol. II, Steel Production, pages 4 and 5,. edited by Bashforth, published in 1951 by Chapman and Hall, Limited, London, England.

Claims

1. A PROCESS OF PRODUCING HIGH QUALITY BESSEMER STEEL, COMPRISING THE STEPS OF INTRODUCING INTO A CUPOLA FURNACE AN IRON-CONTAINING MATERIAL ALSO CONTAINING IMPURITIES WITH AN EXCESS OF CARBON; PASSING INTO THE THUS CHARGED CUPOLA FURNACE A HEATED FLUID CONTAINING FREE OXYGEN AT A TEMPERATURE SUFFICIENTLY HIGH TO OBTAIN BY OXIDATION OF THE CARBON IN THE CHARGE A TEMPERATURE OF AT LEAST 1500*C. IN SAID CUPOLA FURNACE WHILE MAINTAINING A REDUCING ATMOSPHERE THEREIN DUE TO SAID EXCESS OF CARBON, THEREBY MELTING SAID IRON-CONTAINING MATERIAL CONTAINING IMPURITIES IN A REDUCING ATMOSPHERE IN SAID CUPOLA FURNACE WHILE PREVENTING FORMATION OF IRON OXIDES; PASSING SAID MOLTEN IRON-CONTAINING MATERIAL IN SAID CUPOLA FURNACE THROUGH A MOLTEN BASIC SLAG AT A TEMPERATURE OF AT LEAST 1500*C. SO AS TO REMOVE IMPURITIES FROM SAID MOLTEN IRON-CONTAINING MATERIAL AND FROM SUBSTANTIALLY PUR MOLTEN IRON BEING AT A TEMPERATURE OF AT LEAST 1500*C.; AND SUBJECTING SAID MOLTEN IRON WHILE STILL AT A TEMPERATURE OF AT LEAST 1500* C, TO TREATMENT IN A BESSEMER FURNACE, SAID TEMPERATURE OF AT LEAST 1500*C. SUPPLYING THE CALORIES FOR SAID TREATMENT IN SAID BESSEMER FURNACE, THEREBY RAPIDLY FORMING A HIGH QUALITY BESSEMER STEEL.