US3615346A - Process for production of metals in an electric furnace - Google Patents

Process for production of metals in an electric furnace Download PDF

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Publication number
US3615346A
US3615346A US754892A US3615346DA US3615346A US 3615346 A US3615346 A US 3615346A US 754892 A US754892 A US 754892A US 3615346D A US3615346D A US 3615346DA US 3615346 A US3615346 A US 3615346A
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United States
Prior art keywords
furnace
charge
temperature
reduction
combustion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US754892A
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English (en)
Inventor
Johannes A Reth
Winfried H Fettweis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Demag Elektrometallurgie GmbH
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Demag Elektrometallurgie GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Classifications

    • 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
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/527—Charging of the electric furnace
    • 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
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/5211—Manufacture of steel in electric furnaces in an alternating current [AC] electric arc furnace
    • 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
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/5264—Manufacture of alloyed steels including ferro-alloys
    • 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
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B4/00—Electrothermal treatment of ores or metallurgical products for obtaining metals or alloys
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces
    • F27B3/08—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces heated electrically, with or without any other source of heat
    • F27B3/085—Arc furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces
    • F27B3/10—Details, accessories or equipment, e.g. dust-collectors, specially adapted for hearth-type furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D27/00—Stirring devices for molten material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0006—Monitoring the characteristics (composition, quantities, temperature, pressure) of at least one of the gases of the kiln atmosphere and using it as a controlling value
    • F27D2019/0018—Monitoring the temperature of the atmosphere of the kiln
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • a sufficient amount of combustion m g air is supplied to completely burn all of the CO in the reduc- [52] U.S.Cl 75/10, tion gases to form C0,.
  • the amount of combustion air sup- 13/9,75/l1 plied to the closed combustion space is in excess of the [51] Int. Cl C22d 7/00, amount required to effect the complete combustion of the C2lc 5/52 CO
  • the charge is 50] Field of Search 13/l, 2, 9; worked by stirring means or the like to assure the permeability 75/10, l1, 12, 51; 266/30, 31; 9X, 2X, 1X ofits surface for the release ofthe reduction gases.
  • the invention relates to a process for the production of metals or metal alloys in an electric reduction fumace using a charge containing manganese and/or silicon and/or chromium.
  • Open furnaces are used in the production of the alloys specified above since relatively high temperatures-in the order of about 1,700 to 2,000 C.-are required for the production of alloys containing silicon and chromium, the exact reaction temperature being governed by the silicon content.
  • the reduction gases leave the surface of the charge at comparatively high temperatures; this can easily lead to the formation of sinter arches on the charge surface.
  • These sinter arches or bridges greatly restrict the permeability of the chargesurface for gases; as a result, the sudden eruptions of very hot gases through the surface are encountered; the temperature of such gases can exceed 2,000 C.
  • the eruption of hot gases greatly stresses all of the furnace elements and has very adverse effects on the furnace process. To avoid such eruptions, the charge surface must be worked at regular intervals. Normally, thick iron rods are used for this purpose; they are handled manually, or in the case of larger capacity furnaces, manually controlled poking or stirring machines mounted on the furnace platform are used.
  • the reduction gas generated in the reduction area is burned as it exitsfrom the charge surface.
  • the reduction gas generated during such processes has a CO content of about 80 to 90 percent.
  • a volume of air equaling roughly 2.5 times the gas volume is required.
  • Such dust is superfine and is composed mainly of SiO, and/or MnO and/or CrO, or combinations of these metals oxides, the composition depending on the process used
  • the main reason for the generation of the dust can be traced to the fact that the metals reduced during the actual reduction process-in particular Si and Mn or Cr-are evaporated, and oxidize again on leaving the reaction chamber.
  • These superfine particles are carried off by the gases leaving the furnace.
  • fines from thefurnace charge are also removed by the exhaust gases.
  • the object of the present invention is to change the mode of operation and design of open electric reduction furnaces so that the waste gases from such furnaces can be cleaned to the specified degrees of purity on an economically feasible basis.
  • this aim is achieved by reducing the charge in a furnace closed by a roof.
  • combustion air is introduced into the furnace through intake openings having a variable inlet cross section.
  • n denotes the ratio of combustion air to reduction gas under conditions of complete combustion, with the ratio of combustion air to reduction gas averaging 2.5:! and being variable within certain limits as a factor of the reduction gas analysis.
  • An advantageous feature of the proposed process provides for local working of the charge to ensure, at all times, that the surface layer remains uniformly loose, such working of the surface of the charge being effected by using one or more poking or stirring devices capable of continuous operation.
  • the extent of the surface working performed is a function of the temperature distribution throughout the entire furnace chamber, the temperature being measured continuously be means of thermometer probes spaced over the area concerned and located in the vicinity of the furnace roof.
  • a further feature of the proposed process lies in the fact that the operation of the stirring devices for the continuous maintenance of a uniformly loose charge surface is manually controlled on the basis of visual observation of differences in brightness and the distribution of the same over the charge surface using one or more observation instruments that respond to heat radiation.
  • Another advantage exists in the fact that such manual control of the stirring device movements is limited by a fixed control program that prevents the poker as such from being moved into a protective zone around the electrodes.
  • the further features of the invention are of particular advantage from the process technology aspect; in the main, these features provided for the device effecting a series of stirring operations in a limited section of the furnace in accordance with a fixed program and in such a way that certain areas lying on concentric circles are worked in sequence, and also for the fixed stirring program being capable of operation within a where n, air factor using open electric reduction furnaces-on limited section of the furnace-it being possible to select such 5 average 30--and section-as a function of the temperature gradients n; air factor using a furnace in accordance with the invenestablished by the continuous measurement of the temperation-approx. 1.2 to 5- ture distribution throughout the entire furnace chamber. 1.19
  • SiCr (42% SI) 7, 200 670, 000 30 67, 400 2 set to the same limited section of the furnace, and also that the movement of the stirring device can be directed into the point exhibiting the highest temperature as a function of the highest local temperature established by the observation instrument.
  • the furnace required for the process which normally features a water-cooled roof.
  • the furnace roof also features gastight apertures for the gas extraction hoods, charging tubes, and the electrodes.
  • the main feature of the furnace lies in the fact that the roof of the furnace contains apertures arranged about its circumference to permit the entry of the air volume needed for the C0 combustion process, the effective intake cross section of such apertures being variable as a function of the furnace process data.
  • a further characteristic of the reduction furnace required to carry out the process is that the furnace roof or those parts of which that are directed toward the furnace shell and sealed off against the roof as such can be raised and lowered during furnace operation, their lifting movement being controlled as a function of the furnace process data.
  • one of the last features of the furnace roof design in accordance with the invention provides for several or all of the apertures in the furnace roof used to suck in air also being used as entry ports for the stirring or poking device arms.
  • the features of the invention permit a drastic reduction in the volume of waste gas encountered during the operation of electric reduction furnaces, while the expenditure for the overall furnace plant remains within economically justifiable limits and affords adequate consideration for the legal provi- 'sions regarding air pollution.
  • known types of enclosed electric reduction furnaces can be provided with apertures spaced about the circumference of the roof, which-as mentioned above-can be opened and closed.
  • the process can be regulated at any time during the operation of the furnace, whereas to date such furnaces always had to be switched off for such purposes.
  • the air factor is less than one.
  • FIG. 1 is a vertical sectional view of a schematic representation of an enclosed electric reduction furnace embodying the present invention
  • FIG. 2 is a plan view taken along the line A-B in FIG. 1;
  • FIG. 3 is a partial sectional view on an enlarged scale of the furnace roof shown in FIG. I in which an arm of a stirring device extends through an aperture;
  • FIG. 4 is a partial sectional view of the furnace roof similar to FIG. 3, but the aperture for combustion air intake is almost fully closed;
  • FIG. 5 is a horizontal section through the furnace roof along the line C-D of FIG. 1, with the positions of the stirring arm in the vicinity of an electrode indicated schematically;
  • FIG. 6 is a partial side view of the stirring device illustrated schematically, and indicating the various possible positions of the arm;
  • FIG. 7 is a sectional view through the top of the furnace, roughly corresponding to line C-D in FIG. 1, schematically indicating the stirring device and the area around an electrode that can be reached by its arm, and
  • FIG. 8 is a side view illustrating the stirring device shown in FIG. 7 with the various possible vertical positions of its arm.
  • a known open-type furnace l is shown with a roof 2 similar to the known enclosed furnace, which includes a known forced flow water-cooling system using tubular coils (not shown).
  • the height of furnace roof 2 depends on the corn bustion or gas space between surface of the charge and the roof as required for the process in question.
  • the furnace roof 2 can be designed in the known way as a self-supporting structure positioned on the furnace shell 1a or on the furnace operating platform 3 and for sealing against the furnace shell in or for suspension from the next higher platform by using a suitable system. Electrodes 4, 4a, and 4b extend through the furnace roof in the known manner, each passing through an aperture cylinder 5 and being gastight. Placement of the charge into the furnace 1 is also effected in a known way using appropriately distributed charging tubes 7 extending through gastight seals in the furnace roof?
  • the furnace roof 2 contains apertures 2a uniformly distributed about its circumference, or an annular gap may be used, the intake cross sections of which can be varied by means of electropneumatic and/or hydraulic and/or pneumatic control systems 8. Apertures 2a in furnace roof 2 are used for the intake of air (FIG. 4), needed for combustion of the reduction gases generated in the furnace 1.
  • apertures 2a in the roof 2 of the furnace l are arranged so that, using a stirring or poking device 9 arranged to be moved around within the furnace 1, the surface of the charge can be uniformly worked across the entire furnace chamber, the device 9 moving on a circular track 3a arranged around the furnace l.
  • the stirring device 9 works the surface of the charge through the air intake apertures 2a in a section of the furnace chamber that can be selected (FIGS. 5, 7), the working of the surface being carried out in accordance with a preselected program in such a way that points lying on concentric circles are worked in sequence, the programming unit leaving out a protective area around the electrodes 4, 4a and 4b.
  • Thermometer probes 2b are arranged over the area of the furnace roof 2 and continuously measure the temperature and indicate the temperature distribution over the entire furnace chamber. Selection of the furnace section to be worked by the stirring device is effected in accordance with the highest temperature gradient of the indicated temperature distribution.
  • the stirring operation in certain sections of the furnace can be initiated manually or automatically be integration of the temperature gradients.
  • the temperature measured by thermometer probes 2b in furnace roof 2 and the temperature distribution in the furnace chamber permit determination of the section of the furnace in which the surface of the charge 6 must be worked. Accordingly, the stirring device 9 is moved into the appropriate position.
  • observation instruments not shown
  • Infrared cameras or similar appliances as used for military purposes can be employed, but these do not as such form part of the invention.
  • step of checking such at least one parameter comprises continuously measuring the temperature of the waste gases at their outlet from the furnace chamber.
  • a process, as claimed in claim 1, wherein the step of checking such at least one parameter comprises continuously analyzing the waste gases flowing out of the outlet from the furnace chamber to determine the percentage of complete combustion of the reduction gas.
  • step of checking such at least one parameter comprises continuously analyzing the waste gases flowing out of the outlet from the furnace chamber to determine the percentage of complete combustion of the reduction gas.
  • u g 1 9.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • General Engineering & Computer Science (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Furnace Details (AREA)
US754892A 1968-03-19 1968-08-23 Process for production of metals in an electric furnace Expired - Lifetime US3615346A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DED0055615 1968-03-19

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US3615346A true US3615346A (en) 1971-10-26

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US754892A Expired - Lifetime US3615346A (en) 1968-03-19 1968-08-23 Process for production of metals in an electric furnace
US885395A Expired - Lifetime US3679806A (en) 1968-03-19 1969-12-15 Electric reduction furnace

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US885395A Expired - Lifetime US3679806A (en) 1968-03-19 1969-12-15 Electric reduction furnace

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US (2) US3615346A (enrdf_load_stackoverflow)
DE (1) DE1608228B2 (enrdf_load_stackoverflow)
FR (1) FR1575281A (enrdf_load_stackoverflow)
NO (1) NO123952B (enrdf_load_stackoverflow)
SE (1) SE397542B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909499A (en) * 1973-08-08 1975-09-30 Demag Ag Closed reduction furnace
US3985545A (en) * 1970-09-24 1976-10-12 Sadamu Kinoshita Metal melting method using electric arc furnace
US4122296A (en) * 1976-05-21 1978-10-24 Dango & Dienenthal Distributing and poking machine for metallurgical furnaces
DE2929105A1 (de) * 1978-07-18 1980-01-31 Japan Metals & Chem Co Ltd Verfahren und vorrichtung zum raffinieren von ferrosilicium

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49113706A (enrdf_load_stackoverflow) * 1973-03-02 1974-10-30
NO133728C (enrdf_load_stackoverflow) * 1974-04-25 1976-06-16 Elkem Spigerverket As
US5943360A (en) * 1998-04-17 1999-08-24 Fuchs Systems, Inc. Electric arc furnace that uses post combustion
CN107687763B (zh) * 2017-09-01 2019-10-11 攀钢集团研究院有限公司 一种钛渣冶炼电炉加料的方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3043894A (en) * 1958-05-16 1962-07-10 British Iron Steel Research Electric arc furnaces
US3213178A (en) * 1962-08-10 1965-10-19 Elektrokemisk As Process of charging and exhausting gas from electric smelting furnaces
US3303257A (en) * 1963-02-08 1967-02-07 Tanabe Kakoki Co Apparatus for utilizing waste heat of gas generated from an electric smelting furnace
US3258256A (en) * 1963-10-28 1966-06-28 Frank W Brooke Mechanical rabble

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985545A (en) * 1970-09-24 1976-10-12 Sadamu Kinoshita Metal melting method using electric arc furnace
US3909499A (en) * 1973-08-08 1975-09-30 Demag Ag Closed reduction furnace
US4122296A (en) * 1976-05-21 1978-10-24 Dango & Dienenthal Distributing and poking machine for metallurgical furnaces
DE2929105A1 (de) * 1978-07-18 1980-01-31 Japan Metals & Chem Co Ltd Verfahren und vorrichtung zum raffinieren von ferrosilicium
US4255184A (en) * 1978-07-18 1981-03-10 Japan Metals & Chemicals Co., Ltd. Method and apparatus for refining ferrosilicon

Also Published As

Publication number Publication date
DE1608228B2 (de) 1974-01-31
DE1608228A1 (de) 1970-12-10
FR1575281A (enrdf_load_stackoverflow) 1969-07-18
SE397542B (sv) 1977-11-07
NO123952B (enrdf_load_stackoverflow) 1972-02-07
US3679806A (en) 1972-07-25

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