US3598888A - Electric smelting furnace - Google Patents

Electric smelting furnace Download PDF

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Publication number
US3598888A
US3598888A US863470A US3598888DA US3598888A US 3598888 A US3598888 A US 3598888A US 863470 A US863470 A US 863470A US 3598888D A US3598888D A US 3598888DA US 3598888 A US3598888 A US 3598888A
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Prior art keywords
furnace
materials
electrode
chargers
electrodes
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Expired - Lifetime
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US863470A
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English (en)
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Yoshinosuke Tada
Yasunobu Hosoi
Fukio Katsumata
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    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/18—Charging particulate material using a fluid carrier

Definitions

  • the lower end openings of different groups of material charger for different electrodes are also disposed symmetrically with respect to the groups.
  • Each material charger has a means for measuring or measuringr'and recording the change in the quantity of the materials therein. It is possible to attach a pretreating means to the material chargers for preheating, drying, calcining, or prereducing the materials.
  • This invention relates to a three-phase electric smelting furnace having three electrodes arranged to each form the apex of a triangle for smelting pig iron, ferroalloy, nonferrous metals and chemical products, such as calcium carbide, and more particularly to a closed type electric smelting furnace having special means for charging the materials to be smelted therein.
  • An object of the present invention is to provide an electric smelting furnace characterized in that the furnace comprises electrodes, groups of material chargers, each group of said charge equipments belonging exclusively to corresponding one of said electrodes, respectively, and arranged in such a manner that lower end or discharge openings of said material chargers in each group are disposed along a concentric circle around the corresponding electrode in symmetry with respect to the electrode, and at the same time to lower end openings of adjacent groups of said material chargers with each other, and a means for substantially continuously measuring or recording the feeding rate, or the change in the quantity of the materials stored in each ofsaid material chargers, whereby the material consumption for each electrode and material chargers can be observed continuously-as smelting proceeds.
  • high temperature gas substantially free from oxygen is delivered through the materials in each of said material chargers, whereby the materials are preheated and/or pretreated.
  • FIGS. 1 and 2 are examples of sectional plans of the roof level of an electric smelting furnace having three electrodes and actuated by a three phase A.C.- power source, according to the present invention
  • FIG. 3 is a sectional elevation taken along a line abode of FIG. 1;
  • HG. 4 is a chart showing an example ofcurves recorded by measuring the weight change of the materials stored in each material charger assigned for each electrode.
  • FIGS. 1 and 2 illustrating plans at the roof level of the furnace, three vertical electrodes I, II, and III are disposed in the space defined by a furnace wall 7, in a conventional manner, so as to form apices of an equilateral triangle.
  • the figures also illustrate the disposition of the lower end openings of the material chargers operatively connected to each electrode.
  • the material chargers belonging exclusively to the electrode I, ll and ill have the lower end openings 1,2, 3, 4, 5, 6, l', 2', 3', 4', 5', 6', and l", 2", 3", 4", 5", 6", respectively.
  • the material chargers belonging exclusively to the corresponding electrode have the lower end openings disposed along a concentric circle, and in symmetry with respect to the axis ofeach electrode.
  • the lower end openings ofthe material chargers belonging exclusively to adjacent electrodes, e.g., l and II, respectively, are also disposed in symmetry with each other. Due to said arrangement of the lower end openings, each material charger can exclusively feed the materials to the corresponding electrode uniformly along symmetrical directions and substantially not to the other electrodes.
  • each material charger of the illustrated embodiment of the invention comprises a storage tank for temporarily storing the materials, and a trough pipe for feeding the materials from the storage tank to the furnace.
  • a storage tank for temporarily storing the materials
  • a trough pipe for feeding the materials from the storage tank to the furnace.
  • the storage tanks and the trough pipes are unified and referred to as the materials charger, unless otherwise specified.
  • the lower end openings 6 and 2' of the material charger disposed between the electrodes 1 and I] feed the materials exclusively to the corresponding electrodes I and II, respectively, and substantially not to the other electrodes, due to the positions of the lower end openings of the material charger relative to the corresponding electrodes as well as the angle of repose of the materials fed in the furnace, unless disturbances, such as hanging of the materials, take place.
  • those material chargers which are disposed closer to the center of the furnace than the rest i.e. material chargers having the lower end openings 1, l, l" in FIG. land 1,1, 1",6, 6, 6" in FIG. 2 are also disposed in such a manner that they feed the materials exclusively to the corresponding electrodes, and substantially not to the others, although they are not shown in FIG. 3. Furthermore, due to the symmetrical disposition of the group of material chargers belonging to one electrode with respect to the other groups belonging to the adjacent electrodes, each electrode receive the entire quantity of the materials to be smelted by the electrode from those material chargers belonging thereto.
  • the number of the material chargers for each electrode is not restricted to six, as depicted in FIGS. 1 and 2, but four or more material chargers can be used for each electrode, depending on the size of the furnace. It is preferable, however, to use not less than live material chargers per one electrode.
  • the lower end openings belonging to a particular electrode are disposed symmetrically along a circle around the electrode, but the disposition of the lower end openings according tothe present invention is not always limited to strictly symmetrical one. For instance, if the pressure of the materials fed from each lower end opening into the furnace is balanced and does not act to force the electrode away, the lower end openings belonging to an electrode do not always need to be arranged exactly along a concentric circle around the electrode, or to be symmetrically disposed at equal intervals.
  • the electric smelting furnace is featured firstly in that there is provided a plurality of material chargers belonging exclusively to each electrode.
  • the second feature ofthe electric smelting furnace, according to the present invention is in that the weight change of the materials in each material charger or the feeding rate of the materials through each material charger into the furnace is continuously measured for watching.
  • the quantity or amount of the materials in each storage tank can be measured by the volume, height, or weight of the materials therein.
  • known methods for measuring them namely, a method using suspending weight, a method using static capacitance, a method using the piezoelectric effects due to the weight, a method using isotopes, etc.
  • those for measuring the weight of the materials are preferably used, in the electric smelting furnace according to the present invention, for continuous measurement ofthe material quantity, and for recording the change of the amount of the materials as a continuous curve.
  • the same effects are achieved by intermittent measuring and/or recording with appropriate time intervals, instead of absolutely continuous.
  • a weight measuring means is mounted on each storage tank as shown in FIG. 3.
  • the weight measuring means will now be described on the measuring means mounted on the storage tank 8 corresponding to the lower end opening 4 belonging exclusively to the electrode 1, which is substantially the same as the measuring means mounted on the other material chargers.
  • the bottom of the storage tank 8 is contracted in a funnel shape, and a weight measuring means 10, such as a strain-electroresisting element, is mounted on a support structure 9.
  • the funnel shape bottom of the storage tank 8 is connected to the trough pipe 12 by a flexible joint 11 such as a bellows type, and the lower end of the trough pipe 12 is fastened to a furnace roof 13 to form the lower end opening 4 of the material charger.
  • the funnel shape bottom of the storage tank 8 is made to facilitate the measurement of the weight of the materials therein.
  • the weight of the materials in the storage tank 8 can fairly accurately be measured without disturbing the smooth feeding of the materials therethrough. 7
  • the trough pipe 12 When it is difficult to dispose the trough pipe I2 vertically in alignment with the axis of the storage tank 8, due to space limitation above the furnace caused by the electric bus conductor arrangement, the trough pipe 12 can be slanted at a suitable angle, which may be larger than the angle of repose of the materials. And the storage tank 8 can be disposed outside the periphery of the furnace roof 13. The storage tank 8 and the trough pipe 12 are not always restricted to be a straight shape, but if due care is taken in design, curved shape can be adopted. When there is a sufficient space for the material chargers above the furnace, the trough pipe 12 can be shortened or dispensed with by connecting the flexible joint 11 to the furnace roof 13 for directly delivering the materials from the storage tank 8 into the furnace.
  • the weight measuring means is connected to a weight indicator and preferably to a weight recorder, so that the change in the amount of the materials in the storage tank 8 in response to the progress of smelting can be continuously indicated and/or recorded.
  • FIG. 4 illustrates an example of a weight recording chart thus measured.
  • the chart of FIG. 4 also shows that the storage tanks are recharged with the materials after three hours.
  • the materials through the lower end openings 3', 4, and 5' are smelted substantially at the same rate as those of the electrode 1, but the materials through the lower end openings 1, 2, and 6' slower.
  • smelting around the electrode II is not quite smooth and somewhat slower than that around the electrode 1.
  • the change in the amount of the materials is measured continuously, but the measurement can also be made intermittently with short intervals, although continuous measurement and recording are preferable.
  • the inventors succeeded in constructing and operating a large closed type electric smelting furnace for 50 percent Si ferrosilicon with a capacity of 45,000 KVA, which is the largest in the world at the present.
  • a Bus Conductor System for a Three Phase Electric Furnace filed under the application number of U.S. Pat. application Ser. No. 740,237.
  • the electric bus conductor arrangement according to said inventions was applied to said large capacity electric smelting furnace, so as to arrange the bus conductors in orderly and compact fashion. 7
  • the smelting electric load characteristics can be easily be balanced among respective electrodes in the furnace, so that the conditions within the furnace can be controlled smoothly.
  • the electric smelting furnace according to the present invention has other interesting effects.
  • the smelting rate can continuously be determined exactly.
  • the smelting rate or productivity for respective electrode and for the entire furnace can be readily calculated. It is also possible to determine instantaneous electric power consumption per unit weight of products by dividing the electric power load by the productivity.
  • various data useful for the control of the furnace operation can easily be obtained.
  • the material chargers according to the present invention can also be utilized for pretreatments of the materials, such as drying, preheating, calcining and prereducing, etc., so as to save electric power consumption and reducing agents as well as to increase the productivity.
  • pretreatments can be conducted as follows, A closing bell 16 is provided at a funnellike hopper at the top of the storage tank 8, and gastightly closes the upper end opening of the storage tank 8, except the period of charging the materials into the storage tank 8 through the hopper 15, while providing a gas inlet 17 at a funnellike receiving hopper 14 secured at the top of the trough pipe 12 and connected to the storage tank 8 by the flexible joint 11.
  • a gas outlet is mounted at the upper part of the storage tank 8.
  • the materials in the storage tank 8 can be pretreated by introducing hot gas from the gas inlet 17 and discharging it from the gas outlet 18.
  • the hot gases for the pretreatments gas recovered from the furnace or other gases are used after heated by a heatexchanger or burnt partially. It is essential that the hot gas is chemically reducing or inactive and substantially free from oxygen, because if the hot gas contains oxygen in excess ofa certain limit, the carbons in the materials, such as coke and coal, tend to be ignited and burned. On the contrary, the hot gas containing a large amount of reducing gas, such as carbon monoxide and hydrogen, not only dries and heats the materials depending on the temperature and the amount thereof, but also effects preliminary reduction and calcination.
  • reducing gas such as carbon monoxide and hydrogen
  • the exhaust gas from the gas outlet 18 may be purged off after suitable treatment, depending on the properties thereof. If the exhaust gashas other utilities, it may be reused after applying a suitable treatment, or by introducing into the cleaning system of the furnace gas in case ofa closed furnace.
  • the gas pressure under the furnace roof is usually controlled to keep at a level slightly higher than the atmosphere. Accordingly, by properly controlling the pressure, for example, by suctioning, at the upper part of the storage tank 8, the furnace gas can be forced into the material chargers for pretreating the materials. Due care should be taken to keep such pretreatments constant throughout the smelting operation, the extent of which, such as preheating, calcining, and prereduction, affects the electric load characteristics of the materials, such as electric conductivity thereof, as well as the smelting conditions, Continuous measurement and control should be made on the temperature distribution of the materials at various portions in the material chargers, together with the composition of the hot gas introduced therein and the flow rate of the gas at the corresponding portions.
  • such pretreatments can be applied to the materials in the material chargers by other means.
  • the hot gas temperature is below 200 C. effective pretreatments cannot be achieved, and thus the temperature thereof should preferably be as high as possible.
  • a three-phase electric smelting furnace having three electrodes arranged to form the apices of a triangle, comprising three groups each including a plurality of means for charging materials to said furnace, each group of charging means being associated with respectively one of said three electrodes, each group being arranged so that the lower end discharge openings of each of said charging means in each said group are positioned in a generally concentric circle about their associated electrode and spaced symmetrically relative thereto and with respect to the lower end discharge openings of the other adjacent groups of said charging means, and means for substantially continuously measuring the change in the quantity of the charging materials contained in each of said charging means.
  • a smelting furnace as claimed in claim 3 comprising means for substantially continuously recording material quantity consumption in said furnace so as to facilitate constant surveillance of furnace operating conditions.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Combinations Of Kitchen Furniture (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Furnace Details (AREA)
US863470A 1968-10-03 1969-10-03 Electric smelting furnace Expired - Lifetime US3598888A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP43071492A JPS4817403B1 (enrdf_load_stackoverflow) 1968-10-03 1968-10-03

Publications (1)

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US3598888A true US3598888A (en) 1971-08-10

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US863470A Expired - Lifetime US3598888A (en) 1968-10-03 1969-10-03 Electric smelting furnace

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US (1) US3598888A (enrdf_load_stackoverflow)
JP (1) JPS4817403B1 (enrdf_load_stackoverflow)
DE (1) DE1948291A1 (enrdf_load_stackoverflow)
NO (1) NO126399C (enrdf_load_stackoverflow)
SE (1) SE360462B (enrdf_load_stackoverflow)
SU (1) SU436514A3 (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3737554A (en) * 1971-04-14 1973-06-05 Tanabe Kakoki Co Electric smelting furnace of closed-type having dust removing means fixed to exhaust gas vent pipes thereof
US4013401A (en) * 1975-09-18 1977-03-22 Dso "Cherna Metalurgia" Apparatus for preheating a raw material charge for application to an electric furnace
US5479435A (en) * 1993-04-15 1995-12-26 Ishikawajima-Harima Jukogyo Kabushiki Kaisha DC arc furnace
EP0771641A2 (en) 1995-11-01 1997-05-07 Shell Internationale Researchmaatschappij B.V. Process to prepare a blown film of a block copolymer composition
US20140117128A1 (en) * 2011-06-15 2014-05-01 Outotec Oyj Equipment to prepare ore concentrate for pelletizing

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54159325A (en) * 1978-06-08 1979-12-17 Mitsubishi Steel Mfg Recovering waste catalyst
DE2830720C2 (de) * 1978-07-13 1984-03-08 Institut metallurgii imeni 50-letija SSSR Akademii Nauk Gruzinskoj SSR, Tbillisi Einrichtung zur Aufgabe des Einsatzgutes und Ableitung der Reaktionsgase aus geschlossenen Elektroschmelzöfen
NO150774C (no) * 1982-05-03 1984-12-12 Elkem As Fremgangsmaate og anordning ved chargering av en elekrotermisk smelteovn.
AT381788B (de) * 1984-09-18 1986-11-25 Voest Alpine Ag Elektroschmelzofen
FI79560B (fi) * 1988-02-22 1989-09-29 Outokumpu Oy Smaeltugn och foerfarande foer chargering av det material, som behandlas, in i den.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1807090A (en) * 1927-05-18 1931-05-26 Ig Farbenindustrie Ag Charging means for electric furnaces
US3163520A (en) * 1960-12-27 1964-12-29 Elektrokemisk As Process and apparatus for preheating and pre-reduction of charge to electric furnace

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1807090A (en) * 1927-05-18 1931-05-26 Ig Farbenindustrie Ag Charging means for electric furnaces
US3163520A (en) * 1960-12-27 1964-12-29 Elektrokemisk As Process and apparatus for preheating and pre-reduction of charge to electric furnace

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3737554A (en) * 1971-04-14 1973-06-05 Tanabe Kakoki Co Electric smelting furnace of closed-type having dust removing means fixed to exhaust gas vent pipes thereof
US4013401A (en) * 1975-09-18 1977-03-22 Dso "Cherna Metalurgia" Apparatus for preheating a raw material charge for application to an electric furnace
US5479435A (en) * 1993-04-15 1995-12-26 Ishikawajima-Harima Jukogyo Kabushiki Kaisha DC arc furnace
EP0771641A2 (en) 1995-11-01 1997-05-07 Shell Internationale Researchmaatschappij B.V. Process to prepare a blown film of a block copolymer composition
US5658526A (en) * 1995-11-01 1997-08-19 Shell Oil Company Method to prepare blown films of vinyl aromatic/conjugated diolefin block copolymer
US20140117128A1 (en) * 2011-06-15 2014-05-01 Outotec Oyj Equipment to prepare ore concentrate for pelletizing

Also Published As

Publication number Publication date
NO126399C (no) 1982-02-18
SU436514A3 (enrdf_load_stackoverflow) 1974-07-15
NO126399B (enrdf_load_stackoverflow) 1973-01-29
JPS4817403B1 (enrdf_load_stackoverflow) 1973-05-29
DE1948291B2 (enrdf_load_stackoverflow) 1971-01-14
SE360462B (enrdf_load_stackoverflow) 1973-09-24
DE1948291A1 (de) 1970-04-09

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