US3617897A - Method for the refining of a carbonaceous metal melt - Google Patents

Method for the refining of a carbonaceous metal melt Download PDF

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Publication number
US3617897A
US3617897A US818252A US3617897DA US3617897A US 3617897 A US3617897 A US 3617897A US 818252 A US818252 A US 818252A US 3617897D A US3617897D A US 3617897DA US 3617897 A US3617897 A US 3617897A
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Prior art keywords
furnace
refining
melt
slag
percent
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Expired - Lifetime
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US818252A
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English (en)
Inventor
Hans Karl Gustav Sandberg
Erik Axel Bengtsson
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Stora Enso Oyj
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Stora Kopparbergs Bergslags AB
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/32—Blowing from above

Definitions

  • the present invention relates to the refining of a carbonaceous metal melt, particularly, but not exclusively, molten pig iron and other carbonaceous alloyed or unalloyed ferrous materials, the refining being carried out in the presence of slag-forming substances, for example lime material, by blowing with an oxidizing gas, for example oxygen, against the melt in a rotary furnace having a fireproof lining, substantially all the carbon monoxide being burned with the oxidizing gas supplied and the heat thus obtained being transferred to the melt by rotation of the furnace.
  • slag-forming substances for example lime material
  • the first phase When pig iron having a high content of phosphorous (over 1 percent P) is to be refined, the first phase may be completed with a carbon content of 0.5 percent and a phosphorous content of 0.1 percent in the melt. When pig iron poor in phosphorous (below 0.5 percent P) is used, the first phase may be completed with lower carbon contents, towards 0.1 percent. The slag is possibly not tapped off between the two phases in the latter case. In the final phase a high content of iron oxide is desired, inter alia, to obtain a low percentage of phosphorous in the steel finally produced.
  • the final phase of the refining when the carbon content in the melt is low, preferably below 0.5 percent by weight, is carried out with a deficiency of oxygen in the furnace atmosphere.
  • This expression means that there is not enough oxygen to burn all carbon monoxide to carbon dioxide. Because of the high temperature the burning is almost instantaneous and consequently the furnace atmosphere will contain only carbon monoxide and carbon dioxide except in the immediate vicinity of the oxygen jet from the lance.
  • the percentage of carbon monoxide in the furnace atmosphere should preferably be above 50 percent by volume. The best result is obtained if the volumetric or molecular ratio between CO and CO, in the furnace atmosphere is 6:1 or greater. Simultaneously the iron oxide content of the slag is preserved and is preferably above percent by weight Fe.
  • the oxygen deficiency in the furnace atmosphere while retaining the iron oxide content, can be effected by reducing the supply of oxygen gas and simultaneously increasing the supply of iron oxide, for example ore. This will, however, result in a delayed refining and loss of temperature.
  • a better method instead, is to blow the oxidizing gas substantially at right angles to the surface of the metal melt. Furthermore, the distance between the nozzle through which the oxidizing gas is blown and the surface of the melt is short, preferably less than 0.5 m. These measures also ensure that the iron oxide content of the slag is preserved.
  • the furnace is, when stationary, raised to its vertical position, assuming that the rotary furnace is closed at one end.
  • melt and slag After completed refining the melt and slag can be mixed, possibly after the addition of more lime, by rotating the furnace, no oxidizing gas, or very little, being blown in. This is particularly important if the final phase is carried out in a stationary furnace, as the mixing in the stationary furnace often is insufficient.
  • the carbon content of the melt was then 0.5 percent and the phosphorous content 0.1 percent.
  • the wear of the lining in the furnace was measured as about 3 mm. on a representative surface. 0.3 tons of lime and 0.3 tons iron ore were then added and the blowing continued with a different nozzle directing the flow of oxygen gas almost perpendicular to the surface of the melt. The furnace was rotating at the same speed as before. The supply of oxygen gas was then 1.6 Nm. /min./ton. After 4 minutes the blowing was stopped and the steel could be tapped with a carbon content of 0.1 percent and 0.02 percent phosphorous. The wear of the lining during this period was 1.0 mm., compared with 1.9 mm. when the blowing is carried out conventionally.
  • the drawing shows a vertical section of a sloping rotary furnace 1 adapted for refining pig iron or other metals'and provided with a refractory lining 2.
  • the furnace is surrounded by a frame 3 provided with treads 4 for driving rollers 5 and idle rollers 6, the former being driven by a motor 7.
  • Guiding rollers 8 are provided for limiting the axial movement of the furnace.
  • the rollers are journaled in the cradle 9 which is mounted in bearings 10 by pivoting shafts 11 so that the whole furnace can be tipped in different positions suitable for charging and tapping as well as for the heat treatment.
  • the furnace has a single opening 12 located at the center of one end wall.
  • An exhaust gas hood 13 is located in front of this opening when the furnace is in position for the heat treatment at an inclination of eg 15 to 20.
  • the hood is provided with a cooling jacket 14 having water inlet 15 and outlet 16.
  • the exhaust hood is pivoted by about a vertical shaft 18 secured to the base 17 so that it can be swung away and make the furnace accessible for charging, sampling and similar operations.
  • tuyeres Slideable mounted in the hood are two tuyeres, one 19 for the ordinary refining and one 20 for the end step of the refining. Both tuyeres are water cooled as indicated by water inlets 21 and 23 and water outlets 22 and 24, respectively. Gas rich in oxygen is supplied to the pipe 26 to tuyere 19 through the flexible hose 28, and to the pipe 27 of tuyere 20 through the flexible hose 29.
  • both tuyeres are shown in their foremost position but when refining metallic melt according to the invention the refining is started with the tuyere 20 retracted out of the furnace and blowing oxygen only through tuyere 19 until most of the carbon in the melt has be oxidized.
  • the tuyere 19 is retracted and oxygen is instead blown through tuyere 20, which is moved into the position shown in the figure.
  • the mouth of the pipe 27 on the tuyere 20 is directed vertically against the surface of the melt and by restricting the supply of oxygen through the hose 29 the content of carbon monoxide in the atmosphere of the furnace is kept above 50 percent by volume.
  • a method for refining a carbonaceous metal melt in the presence of a slag-forming substance by blowing with an oxidizing gas in a rotary furnace comprising a first step in which the metal melt is refined to a carbon content of about 0.5 percent by weight and substantially all the carbon monoxide formed during this refining is converted to carbon dioxide within the furnace chamber, and a second step in which the refining is carried out with a deficiency of oxygen in the furnace atmosphere corresponding to a carbon monoxide content above 50 percent by volume of the atmosphere.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Manufacture Of Iron (AREA)
US818252A 1968-04-25 1969-04-22 Method for the refining of a carbonaceous metal melt Expired - Lifetime US3617897A (en)

Applications Claiming Priority (1)

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SE561868 1968-04-25

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US (1) US3617897A (es)
BE (1) BE731821A (es)
DE (1) DE1919921A1 (es)
FR (1) FR2007517A1 (es)
GB (1) GB1261401A (es)
LU (1) LU58447A1 (es)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4035179A (en) * 1975-04-04 1977-07-12 Calderon Automation, Inc. Method and apparatus for controlling pollution in steel furnaces
US5377960A (en) * 1993-03-01 1995-01-03 Berry Metal Company Oxygen/carbon blowing lance assembly
EP1260599A3 (de) * 2001-05-25 2003-11-19 Tribovent Verfahrensentwicklung GmbH Drehtrommelofen zum pyrometallurgischen Aufarbeiten von Abfallstoffen in Wirbelbett

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2650978A1 (de) * 1976-11-08 1978-05-11 Graenges Oxeloesunds Jaernverk Frischverfahren durch sauerstoffaufblasen

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB677349A (en) * 1948-10-25 1952-08-13 Stora Kopparabergs Bergslags A Improvements relating to the treatment of molten pig iron or similar iron alloys rich in carbon
US2853377A (en) * 1954-11-25 1958-09-23 Stora Kopparbergs Bergslags Ab Two step refining process in a tiltable rotary furnace
US2902358A (en) * 1957-02-01 1959-09-01 Stora Kopparbergs Bergslags Ab Method of counteracting too high temperature attack on the furnace lining when melting and refining molten metal by means of oxygen containing gases in a rotary furnace
US2977217A (en) * 1957-05-23 1961-03-28 Huettenwerk Oberhausen Ag Method for refining metal baths in rotary drum furnaces
US3100699A (en) * 1959-09-11 1963-08-13 Huettenwerk Oberhausen Ag Control system and process for refining metals
GB991579A (en) * 1961-10-12 1965-05-12 Stora Kopparbergs Bergslags Ab Process for producing pig iron in rotary furnace
US3313619A (en) * 1961-03-24 1967-04-11 Lorraine Laminage Iron refining processes
US3314781A (en) * 1962-03-20 1967-04-18 Stora Kopparbergs Bergslags Ab Method for the control of blast refining of carbon-containing metal melts

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB677349A (en) * 1948-10-25 1952-08-13 Stora Kopparabergs Bergslags A Improvements relating to the treatment of molten pig iron or similar iron alloys rich in carbon
US2853377A (en) * 1954-11-25 1958-09-23 Stora Kopparbergs Bergslags Ab Two step refining process in a tiltable rotary furnace
US2902358A (en) * 1957-02-01 1959-09-01 Stora Kopparbergs Bergslags Ab Method of counteracting too high temperature attack on the furnace lining when melting and refining molten metal by means of oxygen containing gases in a rotary furnace
US2977217A (en) * 1957-05-23 1961-03-28 Huettenwerk Oberhausen Ag Method for refining metal baths in rotary drum furnaces
US3100699A (en) * 1959-09-11 1963-08-13 Huettenwerk Oberhausen Ag Control system and process for refining metals
US3313619A (en) * 1961-03-24 1967-04-11 Lorraine Laminage Iron refining processes
GB991579A (en) * 1961-10-12 1965-05-12 Stora Kopparbergs Bergslags Ab Process for producing pig iron in rotary furnace
US3314781A (en) * 1962-03-20 1967-04-18 Stora Kopparbergs Bergslags Ab Method for the control of blast refining of carbon-containing metal melts

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4035179A (en) * 1975-04-04 1977-07-12 Calderon Automation, Inc. Method and apparatus for controlling pollution in steel furnaces
US5377960A (en) * 1993-03-01 1995-01-03 Berry Metal Company Oxygen/carbon blowing lance assembly
EP1260599A3 (de) * 2001-05-25 2003-11-19 Tribovent Verfahrensentwicklung GmbH Drehtrommelofen zum pyrometallurgischen Aufarbeiten von Abfallstoffen in Wirbelbett

Also Published As

Publication number Publication date
BE731821A (es) 1969-10-01
FR2007517A1 (es) 1970-01-09
GB1261401A (en) 1972-01-26
LU58447A1 (es) 1969-07-21
DE1919921A1 (de) 1969-11-20

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