Self-Baking Electrode

Abstract

An apparatus for a self-baking electrode includes an electrode having at least three zones, a first zone containing uncarbonized carbon-containing composition, a second zone which adjoins the first zone and in which the carbon-containing composition is present in a paste-like or liquid form, a third zone which adjoins the second zone and in which the carbon-containing composition is present in carbonized form, and a cylindrical housing which encloses at least the first and second zones. A tube can be lifted and lowered in a vertical direction at least partly within the zones and an extendable holding element for taking up tensile forces runs partly within the tube and partly outside the tube where a first end of the holding element (101) can be detachably connected to a fastening element, a second end of the holding element enters the third zone and is anchored there.

Claims

1. An apparatus for a self-baking electrode, the electrode comprising at least three zones, a first zone containing uncarbonized carbon-containing composition, a second zone which adjoins the first zone and in which the carbon-containing composition is present in a paste-like to liquid form, a third zone which adjoins the second zone and in which the carbon-containing composition is present in carbonized form, a cylindrical housing which encloses at least the first and second zones the apparatus comprising: a tube which can be lifted and lowered in the vertical direction and runs partly within the cylindrical housing, passes through the first two zones and ends above the third zone, an extendable holding element for taking up tensile forces which runs partly within the tube and partly outside the tube, where a first end of the holding element is able to be detachably connected to a fastening element and a second end of the holding element enters the third zone and is anchored there.

2. The apparatus as claimed in claim 1, wherein the extendable holding element is an extendable rigid element or an extendable flexible element.

3. The apparatus as claimed in claim 2, wherein the extendable rigid element is a rod which consists at least partially of a heat-resistant material which is stable up to a temperature of at least 1000° C.

4. The apparatus as claimed in claim 2, wherein the extendable flexible element is a rope which consists at least partially of a heat-resistant material which is stable up to a temperature of at least 1000° C.

5. The apparatus as claimed in claim 4, wherein the rope comprises a plurality of loops and forms contact regions between two successive loops.

6. The apparatus as claimed in claim 5, wherein the individual loops of the plurality of loops are made at least partially of carbon fibers.

7. The apparatus as claimed in claim 5, wherein the contact regions are provided with a sheath.

8. The apparatus as claimed in claim 5, wherein the individual loops of the plurality of loops are provided with additional holding points.

9. The apparatus as claimed in claim 5, wherein the individual loops of the plurality of loops are provided with additional holding points.

10. The apparatus as claimed in claim 3, wherein the rod comprises a plurality of individual rod elements which are operationally connected to one another.

11. The apparatus as claimed in claim 1, wherein at least the first end of the holding element is configured as a loop or as a rod element, where the loop or the rod element is able to be detachably connected to the fastening element.

12. The apparatus as claimed in claim 1, wherein the holding element can be continuously extended from its first end by connecting a plurality of individual loops or a plurality of individual rod elements.

13. The apparatus as claimed in claim 1, wherein the holding element comprises a plurality of loops connected to one another and having a first loop, a second loop which goes through the first loop, a contact region formed between the first loop and the second loop and the second loop has a first loop part (13B′) and a second loop part and a third loop goes through the two loop parts of the second loop.

14. The apparatus as claimed in claim 1, wherein the tube is unperforated and the tube is perforated.

15. The apparatus as claimed in claim 1, wherein the tube is arranged concentrically to the cylindrical housing of the electrode.

16. The apparatus as claimed in claim 1, wherein the tube is made of metal.

17. The apparatus as claimed in claim 1, wherein the tube is made of a nonferrous metal or alloy.

18. The apparatus as claimed in claim 1, wherein an end element which presses against the third zone when the tube is lowered is provided at an end of the tube which ends above the third zone.

19. The apparatus as claimed in claim 1, wherein a carrier element which presses against the first zone of the electrode when the tube is lowered is provided on each section of the tube) which runs within the cylindrical housing.

20. A holding element comprising a plurality of loops connected to one another, wherein the holding element has a first loop, a second loop which goes through the first loop, a contact region is formed between first and second loops and the second loop has a first loop part and a second loop part and a third loop which goes through the two loop parts of the second loop.

21. The holding element as claimed in claim 1, wherein the individual loops of the plurality of loops consist at least partially of carbon fibers.

22. A process for operating an apparatus as claimed in claim 1, comprising: a first step comprising moving the carbon-containing composition of the three zones relative to the cylindrical housing by vertical lowering movement of the tube, periodic repetition of the first step until the tube has reached the end of the second zone or enters the third zone, subsequently decreasing the load on the holding element by reducing the tensile forces acting on the holding element, extending the holding element and securing the extended holding element by means of a fastening element, applying a tensile force to the extended holding element, lifting the tube until it is again located within the first zone, recommencement with the first step.

23. The process as claimed in claim 22, wherein the extension of the holding element is effected by extending the end of the holding element which can be connected to the fastening element by connecting with at least one further loop or with at least one further rod element.

24. An electrode comprising an apparatus as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The invention will be illustrated in more detail below with the aid of working examples in conjunction with the drawings. The Figures show:

[0027] FIG. 1 schematically shows a partial section (longitudinal section) through a self-baking electrode with apparatus according to the invention, where the holding element is configured as a rope and the tube is equipped with carrier elements.

[0028] FIG. 2a schematically shows a part of the holding element and its construction from the individual loops.

[0029] FIG. 2b schematically shows an individual loop of the holding element which is provided with carbon fiber parts pushed through and a sheath in the contact region.

[0030] FIG. 3 schematically shows a partial section (longitudinal section) through a self-baking electrode with apparatus according to the invention, where the holding element is configured as a rod with individual rod elements and the tube is equipped with carrier elements.

[0031] FIG. 4 schematically shows a partial section (longitudinal section) through a self-baking electrode with apparatus according to the invention, where the holding element is configured as a rope and the tube (without carrier elements) is perforated.

DETAILED DESCRIPTION

[0032] A partial section through the self-baking electrode with an apparatus according to the invention is shown schematically in FIG. 1. The electrode 1 comprises a cylindrical housing 2 in the form of a sheet metal outer wall which is continuously filled with particulate carbon-containing composition (briquettes). Means 9 which enable the housing to be moved in the vertical direction are arranged on the cylindrical housing 2. This is referred to as outer wall replacement. These means are connected to the constructional plant structure which surrounds the apparatus of the invention (not visible in FIG. 1). The means are, for example, two outer wall clamping rings 91 and 92 which are arranged opposite one another viewed in the vertical direction and are connected to one another by replacement hydraulics, for example displacement cylinder 93.

[0033] The first outer wall clamping ring 91 is referred to as the upper outer wall clamping ring 91 and the second outer wall clamping ring 92, which is, viewed in the vertical direction, located underneath the first outer wall clamping ring, is referred to as lower outer wall clamping ring 92. The cylindrical housing 2, namely the sheet metal outer wall, runs within these two outer wall clamping rings 91, 92 and is clamped in place by these. The outer wall replacement is effected by alternate opening of the outer wall clamping rings 91, 92 and appropriate vertical movements triggered by the replacement hydraulics, namely the displacement cylinder 93. The outer wall replacement can be described as follows: the lowermost of the two outer wall clamping rings 92 is opened, the upper outer wall clamping ring 91 grips the cylindrical housing 2 firmly and is lowered hydraulically in the direction of the lower outer wall clamping ring 92. The lower clamping ring 92 is closed and clamps the cylindrical housing 2 firmly. The upper outer wall clamping ring 91 is opened and moved upward hydraulically to its starting position. Electric energy is supplied to the electrode via contact jaws 3, likewise arranged on the cylindrical housing 2. The thermal energy given off by the material being melted serves as further energy source. As a result of the energy input, the particulate carbon-containing composition, also referred to as uncarbonized Soderberg composition, goes over from a paste-like state into a liquid state and finally into a solid state. The solid state is also referred to as a carbonized Soderberg composition. This is shown in simplified form as three zones 4, 5 and 6 in FIG. 1. The first zone 4 comprises uncarbonized carbon-containing composition. In the second zone 5, this composition is present in paste-like to liquid form and in the third zone 6 is present in carbonized form. Zone 6 is shown only in part in FIG. 1. This zone is the region of the electrode 1 which dips into the reaction zone of the furnace (not visible in FIG. 1). In the reaction zone of the furnace, ore (SiO.sub.2) is reduced to metallic silicon by addition of carbon (e.g. wood charcoal, low-ash coal and wood chips). The electric energy required (electric arc or plasma) is introduced by the electrode 1. The electrode 1 is consumed in the process.

[0034] FIG. 1 depicts a tube 7. This is partly arranged outside the electrode (region 71) and partly within the electrode (region 72). A section of the tube 7 which is arranged in the region 72 passes through the first and second zones 4, 5. The tube 7 does not reach the third zone 6 in which the carbon is present in carbonized and therefore solid form. In the embodiment shown schematically in FIG. 1, the tube 7 is arranged concentrically to the cylindrical housing 2.

[0035] As can likewise be seen in FIG. 1, a holding element 100 configured as rope 10 runs partly within the tube 7. The tube 7 protects the holding element 100 configured as rope 10 from mechanical damage, in particular in the first zone 4 of the electrode in which the carbon-containing composition is present in uncarbonized form, frequently in the form of sharp-edged particulate material. Unlike tube 7, a second end 102 of the holding element 100 which is no longer surrounded by the tube 7 goes into the third zone 6 of the electrode. It is fixed there in the carbonized carbon-containing composition, namely “baked-in” (second end 102 of the holding element 100 not visible in its entirety in FIG. 1). A first end 101 of the holding element which is located opposite the second end 102 is detachably connected to a fastening element 11. The fastening element 11 is, for example, a clamping means or, as shown schematically in FIG. 1, a pin 110 on which the holding element 100 configured as rope 10 is hung and from which the holding element 100 configured as rope 10 can be detached again. The holding element 100 serves first and foremost to take up tensile forces and hold the electrode 1.

[0036] In the embodiment depicted in FIG. 1, the holding element 100 configured as rope 10 comprises a plurality of interlocking loops 13. The first holding element end 101 configured as first loop 13 is hung on the pin 10. The holding element 100 configured as rope 10 is continuously extendable by joining a loop 13 to a second loop 13 and the second loop 13 to a third loop 13 (etc.). A loop 13 is configured as a closed ring. The individual loops are made of carbon fibers. A preferred embodiment of these loops 13 and the possibility of joining these individual loops 13 to one another is depicted in FIGS. 2a and 2b.

[0037] In each region 71 of the tube 7 which runs outside the electrode, means 8 for moving the tube 7 vertically are provided. These means are connected to the constructional plant structure which surrounds the apparatus of the invention (not visible in FIG. 1).

[0038] Such means 8 are, for example, two clamping rings 81, 82 which are arranged opposite one another in the vertical direction and are connected to one another by a displacement cylinder 83. The first clamping ring 81 is referred to as the upper clamping ring and the second clamping ring which, viewed in the vertical direction, is located underneath the first clamping ring is referred to as the lower clamping ring 82. The tube runs within these two clamping rings 81, 82 and is clamped in place by these. The replacement can be described as follows: the lowermost of the two clamping rings 82 is opened, the upper clamping ring 81 clamps the tube firmly and is lowered hydraulically in the direction of the lower clamping ring 82. The lower clamping ring 82 is closed and clamps the tube 7 firmly. The upper clamping ring 81 is opened and moved upward hydraulically to its starting position.

[0039] On actuation of the means 8, the tube 7 moves within the uncarbonized carbon-containing composition of the first zone 4 and the paste-like to liquid composition of the second zone 5 and exercises corresponding shear and/or compressive forces on the third zone 6. In the reduction process, the carbonized carbon-containing composition from the third zone 6 is consumed. The same also applies to the holding element 100, in particular to each region of the holding element which runs in the third zone 6. As a result of the replacement, carbonized carbon-containing composition is continuously supplied and is continually consumed by the continuous burning away of the electrode. To assist the replacement process, a carrier element 12 which on vertical movement of the tube 6 presses against the uncarbonized carbon-containing composition of the first zone 4 is optionally provided on the outside of the tube 7. The holding element 100 is continuously extendable. In the embodiment shown in FIG. 1, the loop 13 which forms the first end 101 of the holding element 100 is detached from the pin 110 and connected to a further loop 13 which is then hung on the pin 110 again. In this way, the holding element 100 is extended continuously as required.

[0040] FIG. 2a depicts parts of the holding element 100 made up of individual loops 13 connected to one another to form a rope 10. Each of the loops 13 is, in the embodiment shown in FIG. 2, configured as a closed ring. An illustrative material for the loops 13 is a woven material composed of carbon fibers. The third zone 6 consisting of carbonized solid Soderberg composition is shown schematically. In this third zone, the second holding element end 102 is fixed, namely “baked-in”. In the embodiment shown in FIG. 2, the second holding element end 102 comprises two loops 13A and 13B. The two loops 13A and 13B are joined to one another by a third loop 13C. The third loop 13C goes through the two loops 13A and 13B. A contact region 130 between the two loops 13A and 13B and the third loop 13C results. As shown in FIG. 2, the loop 13C then comprises a first loop part 13C′ and a second loop part 13C″. The next loop 13D goes through these two loop parts. A contact region 131 then results between the first loop part 13C, second loop part 13C″ and the loop 13D. The loop 13D comprises a first loop part 13D′ and a second loop part 13D″. A subsequent loop 13E (indicated as broken-line arrow in FIG. 2) goes through the first loop part 13D′ and the second loop part 13D″. A contact region 132 between the two loop parts 13D′ and 13D″ results. The loop 13E comprises a first loop part 13E′ and a second loop part 13E″, through which the next loop 13F goes (no longer visible in FIG. 2a). Depending on the desired length, the holding element 100 comprises a particular number of loops which are joined to one another in the manner described above. In the embodiment of a holding element 100 shown in FIG. 2a, as is used in the apparatus of the invention, the second holding element end 102 is formed by two loops 13A and 13B which are joined by the third loop 13C. It is conceivable to use another anchoring element, for example a type of hook, by means of which the second holding element end 102 is anchored in the carbonized Soderberg composition instead of the two loops 13A and 13B. The second holding element end 102 (not visible in FIG. 2) is, in a preferred embodiment, configured in the same way as, for example, the loop 13D depicted in FIG. 2a. The two loop parts 13D′ and 13D″ are hung on the pin 10 (cf. FIG. 1) and form the end of the holding element 100. As an alternative, an additional further anchoring element, e.g. likewise a hook, which connects the two loop parts to the pin can be provided between the loop parts and the pin 10.

[0041] FIG. 2b shows an enlarged view of the loop 13D (as per FIG. 2a) with loop parts 13D′ and 13D″ and the contact regions 131 and 132 thereof with loops 13C or 13E. The contact region 131 is provided with a coating or sheath 134 composed of a fiber composite. The loop 13D is provided with additional holding points 133 in the form of carbon fiber parts having knots at the ends.

[0042] FIG. 3 shows the depiction of FIG. 1 with the difference that the holding element 100 is configured as a rod 20 made up of individual rod elements 21. The rod (20) can be extended as required by juxtaposition of the rod elements (21). The rod elements (21) are operatively connected at their ends, for example by means of a plug or screw connection.

[0043] The first end of the holding element 101 comprises a fastening means 11 which in the embodiment of FIG. 3 is configured by way of example as clip into which an end of the rod element (21) can be clamped (clip not visible in FIG. 3).

[0044] FIG. 4 shows the depiction of FIG. 1 with the difference that the tube 7a is perforated and no carrier elements are provided on the outside of the tube 7a. It can also be seen that the tube 7a goes into the third zone 6. The perforations 7b make it possible for the uncarbonized, carbon-containing composition to get into the interior of the tube 7a, which makes the use of carrier elements as in FIG. 1 (12) for exerting pressure on the uncarbonized, carbon-containing composition of the first zone 4 superfluous.

LIST OF REFERENCE NUMERALS

[0045] 1 Electrode [0046] 2 Cylindrical housing [0047] 3 Contact jaws [0048] 4 First zone (uncarbonized Soderberg composition) [0049] 5 Second zone (paste-like to liquid Soderberg composition) [0050] 6 Third zone (carbonized, solid Soderberg composition) [0051] 7 Tube [0052] 7a Tube (perforated) [0053] 7b Perforations [0054] 71 Tube region outside the electrode [0055] 72 Tube region within the electrode [0056] 8 Means for moving the tube vertically [0057] 9 Means for moving the cylindrical housing vertically [0058] 10 Rope [0059] 100 Holding element [0060] 101 First holding element end [0061] 102 Second holding element end [0062] 11 Fastening element [0063] 12 Carrier element [0064] 13 A, B, C, D, E loops [0065] 13 C′, C″, D′, D″ loop parts [0066] 130, 131, 132 Contact region [0067] 133 Holding points [0068] 134 Sheath