ZA200101286B - Söderberg-type composite electrode for ARC smelting furnace. - Google Patents
Söderberg-type composite electrode for ARC smelting furnace. Download PDFInfo
- Publication number
- ZA200101286B ZA200101286B ZA200101286A ZA200101286A ZA200101286B ZA 200101286 B ZA200101286 B ZA 200101286B ZA 200101286 A ZA200101286 A ZA 200101286A ZA 200101286 A ZA200101286 A ZA 200101286A ZA 200101286 B ZA200101286 B ZA 200101286B
- Authority
- ZA
- South Africa
- Prior art keywords
- electrode
- casing
- baked
- furnace
- paste
- Prior art date
Links
- 238000003723 Smelting Methods 0.000 title claims description 14
- 239000002131 composite material Substances 0.000 title description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 20
- 229910002804 graphite Inorganic materials 0.000 claims description 19
- 239000010439 graphite Substances 0.000 claims description 19
- 239000002003 electrode paste Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000004020 conductor Substances 0.000 claims 1
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 238000004873 anchoring Methods 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 210000002445 nipple Anatomy 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000604 Ferrochrome Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- YDZQQRWRVYGNER-UHFFFAOYSA-N iron;titanium;trihydrate Chemical compound O.O.O.[Ti].[Fe] YDZQQRWRVYGNER-UHFFFAOYSA-N 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000008774 maternal effect Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000003923 scrap metal Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Description
SUDERBERG-TYPE COMPOSITE ELECTRCDE FOR ARC SMELTING FURNACE
This invention relates to smelting.
Smelting is an important process used for the production of many metals and alloys. Smelting takes place in a furnace with the heat necessary to melt the contents of the furnace being produced electrically. A DC arc plasma furnace is an example of a smelting furnace in which pre-baked graphite electrodes are conventionally used to direct electrical energy into the furnace bath. The consumption of the electrodes is an important cost item in the use of such a furnace.
Soderberg electrodes are used in various smelting processes. The Soderberg electrode comprises a casing which may have a plurality of inwardly projecting ribs. Electrode paste, which typically comprises a mixture of a carbonaceous material and a hydrocarbon binder, is introduced into one end of the casing. The paste passes down the casing until 2 zone is reached where it is subjected to a suitable calcining temperature to expel volatile substances and bake the paste into a hard form. The hard form emerges from an end of the casing and forms the working end of the electrode.
CONFRMANON COPY
The present invention provides the use of a pre-baked graphite or similar electrode in combination with a Sdderberg electrode.
Thus, according to a first aspect of the invention, an electrode for a smelting furnace comprises: an elongate casing including a plurality of spaced, inwardly projecting ribs extending radially from an inner surface of the casing towards the centre of the casing; a central core of a pre-baked electrode disposed within the casing free of the projecting nbs and defining a space between the core and the inner surface of the casing; a heating zone located intermediate the ends of the casing; and a carbonaceous electrode paste received or receivable within the space between the core and the inner surface of the casing, the paste being arranged to be calcined into a baked, hard form upon entering the heating zone.
The central core may either be a solid pre-baked graphite electrode or a hollow pre-baked graphite electrode defining a feed passage between open ends thereof for feeding charge material into the furnace.
-3 =
The ribs are typically in the form of planar fins formed from an electrically conductive maternal, in particular mild steel or stainless steel. They preferably include a plurality of transversely formed apertures or holes for allowing electrode paste to pass through them so as to anchor or support the electrode upon baking.
The combined electrode of the invention will generally be cylindrical in shape and may be made of larger diameter than conventional pre-baked graphite electrodes. This enables the use of larger electrode currents and increased operating capacity. Further, the consumption of expensive graphite electrodes 1s reduced.
The invention has particular application to AC or DC arc plasma furnaces or Soderberg submerged arc furnaces and in the smelting applications } where pre-baked graphite electrodes have traditionally been used.
BRIEF DESCRI F THE D
Figure 1 is a schematic sectional side view of a first embodiment of the invention,
Figure 2 is a section along the line 2-2 of Figure 1,
Figure 3 is a schematic sectional side view of a second embodiment of the invention, and
Figure 4 is a section along the line 4-4 of Figure 3.
A first embodiment of the invention will now be described with reference to Figures 1 and 2. Referring to these figures, an electrode for use in a smelting furnace comprises an elongate cylindrical casing 10 mounted in an electrode holder 12. The mounting of the casing 10 in the holder 12 is such that it is possible to push the casing 10 through the holder 12 as the electrode is consumed, in use. The casing 10 has a plurality of spaced inwardly projecting ribs 14. The casing 10 and ribs 14 are typically formed from mild steel although any other suitable material such as stainless steel, for example, can be used.
Centrally located in the casing 10 is a solid pre-baked graphite electrode 16. A space Is provided between the electrode 16 and the casing 10. \
Electrode paste 18 1s introduced into the space. This electrode paste is typically a mixture of a carbonaceous material such as calcined anthracite and a hydrocarbon binder such as pitch or tar. The paste slides down to zone 20 where it softens, and then to zone 22 where it is subjected to temperatures of the order of 400°C to 600°C. The level of this baking zone 22 may be controlled by using a heating or cooling device located just above holder 12, and monitored by continuous temperature measuring using a thermocouple, for example, in accordance with conventional methods. Volatile substances in the paste are expelled and it is calcined into a hard form. What emerges from the working end 24 of the casing 1s a pre-baked graphite core 16 surrounded by calcined hard paste 26.
© WO 00/1226 PCT/IB99/01458
It is envisaged that apertures or holes may be transversely formed through the projecting ribs 14 to allow electrode paste 18 to pass through them.
Upon the paste hardening, the ribs 14 will anchor the calcined paste in place so as to provide support therefor. This releases the strain on the nipples between adjacent pre-baked electrodes. This reduces the risk of joint fracture and thus the risk of portions of the pre-baked electrode becoming dislodged and falling into the furnace. Being clectrically conductive, the ribs or fins 14 also assist in baking the electrode paste 18.
In use, as the electrode is consumed, the casing 10 is pushed through the hole 12 and deeper into the furnace. The casing 10 and core 16 are replenished and further electrode paste 18 introduced into the space between the core 16 and casing 10. If desirable, anchoring means (not shown) may be provided for anchoring the graphite electrode 16 to the casing 10 prior to introducing the paste 18 into the space between them.
The embodiment of Figures 3 and 4 is similar to that of the embodiment of
Figures 1 and 2 and like parts carry like numerals. The electrode of this embodiment differs from that of the first embodiment in that a hole or feed passage 28 is axially formed through the core 16. Feed material for the furnace can be delivered through the feed passage 28. The provision of holes or apertures in the ribs 14, as described above, allow the use of relatively thin walled pre-baked electrodes with larger diameter feed passages without increasing the risk of joint fracture.
The electrodes described above have particular application in AC or DC arc plasma furnaces where traditionally pre-baked graphite electrodes have been used. The consumption of the expensive pre-baked graphite
Co. oo electrodes is reduced and, as a result, downtime is reduced. Further, larger diameter electrodes are possible enabling the use of higher electrode currents and increased operating capacity. In addition, the pre-baked graphite electrodes require less machining than conventional electrodes, if at all. Further, there is believed to be less oxidation of the pre-baked graphite electrodes due to the surrounding paste 18. The calcined hard paste 26 also assists supporting and strengthening the joints or nipples between joined electrodes. Due to the reduced graphite consumption, if desirable, lower current densities and less expensive quality graphite may be used. Alternatively, a thinner pre-baked electrode core may be used.
In the case of the hollow core pre-baked electrode, the diameter of the hollow core may be increased to provide faster feeding of the feed material and, it is believed, better distribution thereof.
It is also envisaged that a conventional Soderberg electrode may be converted to a compound electrode as described previously by including a central core of a solid or hollow pre-baked graphite electrode or the like therein. It is believed that this will lead to an increase in the rate of baking of the paste and higher current densities resulting in increased productivity.
As a result of the form of the combined electrode, it is envisaged that a working platform may be formed around the electrode. This allows for the repairing of the electrode and other tasks such as welding, for example, to be effected.
The electrodes are particularly useful in the smelting of ferrochromium and in the reduction of ores such as ilmenite.
They also have application in the smelting of scrap metal in steel furnaces.
Claims (8)
1. An electrode for a smelting fumace comprising: an elongate casing including a plurality of spaced, inwardly projecting ribs extending radially from an inner surface of the casing towards the centre of the casing; a central core of a pre-baked electrode disposed within the casing free of the projecting ribs and defining a space between the core and the inner surface of the casing; a heating zone located intermediate the ends of the casing; and } a carbonaceous electrode paste received or receivable within the space between the core and the inner surface of the casing, the paste being arranged to be calcined into a baked, hard form upon entering the heating zone.
2. An electrode according to claim 1 wherein, the central core is a solid pre-baked graphite electrode.
3. An electrode according to claim 1 wherein, the central core is a hollow pre-baked graphite electrode defining a feed passage between open ends thereof for feeding charge material into the furnace.
4, An electrode according to any one of the preceding claims, wherein the inwardly projecting ribs are in the form of planar fins formed from an electrically conductive material.
S. An electrode according to claim 4, wherein the fins include a plurality of transversely formed apertures or holes for allowing electrode paste to pass through them so as to anchor or support the electrode upon baking.
6. An electrode according to claim 4 or claim 5, wherein the ribs arc formed of mild steel or stainless steel.
7. An electrode according to any onc of the preceding claims, wherein the combined electrode is cylindrical in shape and larger in diameter A than a conventional pre-baked graphite electrode.
8. An electrode according to any one of the preceding claims, wherein the smelting furnace is a DC arc plasma furnace, an AC arc plasma furnace, or a Soderberg submerged arc furnace.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA200101286A ZA200101286B (en) | 1998-08-25 | 2001-02-15 | Söderberg-type composite electrode for ARC smelting furnace. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA987131 | 1998-08-25 | ||
ZA200101286A ZA200101286B (en) | 1998-08-25 | 2001-02-15 | Söderberg-type composite electrode for ARC smelting furnace. |
Publications (1)
Publication Number | Publication Date |
---|---|
ZA200101286B true ZA200101286B (en) | 2001-09-03 |
Family
ID=27760710
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
ZA200101286A ZA200101286B (en) | 1998-08-25 | 2001-02-15 | Söderberg-type composite electrode for ARC smelting furnace. |
Country Status (1)
Country | Link |
---|---|
ZA (1) | ZA200101286B (en) |
-
2001
- 2001-02-15 ZA ZA200101286A patent/ZA200101286B/en unknown
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