SK286447B6 - Soderberg-type electrode for making silicon alloys and silicon metal - Google Patents

Abstract

The self-baking electrode suitable for use in an electric arc furnace comprises an elongated open ended electrically conductive casing for extending generally vertically within the furnace. A central core made of a heat conductive material is disposed within and spaced from the casing. A framework within is securing the central core to an inner surface of the casing for holding centrally the central core within the casing and for preventing an extrusion of the central core downward. The central core is surrounded by a carbonaceous electrode paste devised to cure into a solid electrode upon heating and to bond to the central core. This self-baking electrode allows the production of silicon metal in a Soderberg-type furnace without any modification to the usual slipping system or addition of another slipping system. An electrode according to the invention allows the same furnace to produce both FeSi of any grade and Si metal without any downtime between the gradual change from one product to the other and each time at the lowest electrode cost.

Description

Technical field

The present invention relates to a self-baking electrode for producing silicone alloys and silicone metal, an electric arc furnace, and a method for producing a self-baking electrode.

BACKGROUND OF THE INVENTION

The use of self-baking electrodes (also "Soderberg electrodes") for the production of ferrous alloys has been known for about 75 years (see U.S. Patent No. 1,440,724 of September 1919 and U.S. Patent No. 1,441,037 of January 1923 both under the name of Söderberg). The self-baking electrodes consist essentially of a carbon-containing material such as anthracite, coke, tar and pitch which fills the steel casing in position inside the electric arc furnace by means of contact tips and a suspension and sliding device. The use of the high voltage and glow of the arc ignited by the electrode during operation of the furnace generates sufficient heat to melt the material filled into the package and form the sealant and then coke the resulting sealant and finally burn the electrode.

The steel sheaths of the Soderberg electrodes now in use are mostly round and equipped with rows of internally projecting pleats disposed radially toward the center of the electrode to obtain the mechanical force of the electrode, the heat transfer in the electrode through the conductivity of the plent. He behaves like a regular driver. Plets and casing are usually made of perfect steel and their quantity, length and physical shape depend on what is considered to be the optimum for perfect firing on any geometric design.

Since the electrode consumes both the sealant and the casing during manufacture of the silicone or ferrous alloy, they can be replaced. This action takes place high at the top of the electrode column in such a way that there is sufficient static pressure for coherence and to run through the various degrees of the temperature model from softening the sealant to the heat generated by the current flow.

Electrode consumption is replaced by perfect sliding of the electrode through the contact tips. The iron casing and the plungers passing through the CSC contact tips burn and oxidize or melt each time they are swung and thereby fall into the mixture. Because of this consumption / oxidation, the iron recovery is in such an amount that Söderberg technology cannot be used to produce a commercial grade silicone metal where, according to the grade for Si, Fe content should be below 1%, below 0.5%, below 0, 35% or even below 0.2%.

Therefore, the silicone metal is produced exclusively by using a so-called "pre-baking" electrode, which is an amorphous carbon or semi-graphitized electrode made in special manufacturing plants, and is then supplied in parts of a typical length of 2 to 2.5 m. These pre-baking electrodes, which are typically 4 to 6 times more expensive than Söderberg electrodes, are to be connected to each other by certain devices, such as plugs and sockets or a set of male / female structural cuts at the ends of each electrode piece. In the operation of a silicone metal furnace, these relationships between electrode fragments are limiting factors for the transfer of energy from one electrode to the other below the contact tip.

For the heat and current transfer of the model, the plugs and sockets are susceptible to breakage due to sudden changes in the furnace energy - which is caused by any type of power cut - so breakage of the electrode is part of an unwanted negative impact in operation.

Moreover, their strength is relatively low when compared to Söderberg electrodes, which do not contain weak points in terms of connectors or plugs, making it stronger and capable of receiving energy per square piece.

Therefore, reducing the cost of an electrode using the self-baking principle is one of the major visions of any silicone metal manufacturer.

Many attempts have been made to develop a type of Söderberg electrode that would allow cheaper production of silicone metal while meeting all the criteria for reducing the amount of iron in the metal produced.

In the 70 ', Nippon Denko in Japan developed a system in which packaging and plinths, usually made of steel, are replaced by packaging and plungers made of aluminum (see Japanese Patent Nos. 951 888 and 835 596). This attempt to use aluminum for the wrapper and the plinths has never been used industrially because of the lack of mechanical stability and substantially different conductivity of aluminum compared to steel.

Another approach was taken by Mr Cavigli (see Italian Patent No. 606,568 of July 1960). This patent proposed to remove the web from the outer wrapper and to adjust the movement of the sealant relative to the outer wrapper by sliding or extruding the outer wrapper content as a centrally necessary component. Iron crosses were introduced inside the package to support the firing electrode. These iron crosses held the electrode as long as relative shifting between the sheath and the electrode was allowed, either by injecting or reducing the weight of the suspension. This system was in operation in a factory in Italy. It makes it possible to reduce the contamination of iron; But it does not allow to achieve the same low level of iron contamination as is done with conventional pre-firing electrodes.

Another approach was taken by Bruff (see U.S. Patent No. 4,527,329, July 1985). This patent proposes to divide the baking of the sealant from that which occurs by using heat by means of Ohm resistance and conductivity, and under contact

SK 286447 Β6 spikes. Thus, a special firing device is positioned above the contact tips. In addition, the invention is provided for cutting and removing the iron wrapper below the firing system, above the contact tips, such that a base-shaped firing electrode enters and connects to the contact tips. This system is converted in a small furnace around 10 MW in Elkem Kristiansand. However, there are some limitations to the use of higher voltage furnaces with larger diamond electrodes, which are the production standard for price efficiency in the developed world.

A similar solution has been explained in German Patent No. 5,938,549. No. 4,036,133 of May 1991 under the name of E. Svan.

Another system based on the proportional development of a self-baking electrode relative to the outer sheath was illustrated by Persson in U.S. Pat. No. 4,575,856 of March 1986. In this patent, the iron crosses used by Caviglim in its system are replaced by smaller graphite electrodes introduced into the center of the package. The small electrodes were supported and were driven by a special slip / hold device that allows relative movement within the package.

An improved system based on the "transfer" of a conventional pre-firing electrode of one of the designated types described by Cavigli and Persson in U.S. Patent No. 5,201,549. 2,081,295.

The disadvantages of this system result from the physical force of the graphite electrode core limitations and their limited potential for absorbing voltage induction and braking forces, since the electrode core is substantially unmaintained to a length of 14 m and may be perpendicular to the position for various reasons. Further, the package, which in this system is essentially an extruding ink, needs to slide down for replacement, for thermal damage between and below the contact tips. Without such periodic rearrangement, the damage would reach high values in the nibs, and the liquid sealant would start to drip, causing a failure called "green" breakage of Soderberg technology. Periodic rearrangement of the packaging contaminates Si not only with the furnace iron, but also with the alloy elements used in the packaging material and the determination of the maximum heat to protect oxidation. These contaminants have the effect that the silicone metal produced in this way is unsuitable for use in the chemical industry for the production of methylchlorosilanes from the silicone metal. Packaging made of stainless steel also has drawbacks such as reducing the heat important properties for operation, the furnace environment and the time at which they are exposed to this.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new and improved self-baking electrode.

Another object of the present invention is to provide a new electrode assembly that enables the production of silicone metal in a Söderberg-type furnace of any modification of an existing shear assembly or the addition of another shear assembly. Thanks to the electrode of the invention, the same furnace can also produce FeSi of each stage and the metal Si without any deterioration between the gradual change of one product to another at any time at the lowest cost of the electrode.

The electrode as the invention overcomes the problems associated with the preferred field: contamination of the silicone metal by core breakage as a result of the displacement forces, deformation of the shell, loss of production and substantial expense for the establishment of a new shear system. It also provides a method for converting larger and more efficient Söderberg-type ferrosilicon furnaces into existing silicone metal furnaces with pre-firing technology.

Accordingly, the present invention relates to a self-baking electrode in a position for producing silicone metal and silicone alloys suitable for use in an electric arc furnace, the electrode comprising:

an elongated, electrical conductive casing open at the end, which normally extends perpendicular to the furnace during operation;

a central core housed in a furnace and separated from the packaging, a central core made of a heat conducting material;

at least one structural frame, a structural package securing the central core to the inner surface of the package to hold the central core within the package and prevent the central core from being pushed downwards; and

a carbon electrode sealant surrounding the central core, the sealant is intended to wrap a solid electrode for heating and attachment to the central core.

The present invention relates to an electric arc furnace comprising a self-baking electrode for producing silicone metal and silicone metal alloys as described. More specifically, the electric arc furnace comprises:

the furnace itself containing a charge for igniting the furnace;

a self-baking electrode comprising: a longitudinal electrical conductive cover open having an upper and a lower end, say, a cover spread perpendicularly within the furnace and released to slide perpendicularly through the slide mechanism;

- a central core located within the furnace and away from the packaging, the central core being made of a heat-conducting material;

at least one structural frame in the package, a structural frame that maintains the central core to the inner surface of the package to maintain the center of the central core within the package and to prevent the central core from being pushed down through the lower end of the package;

a carbon electrode sealant surrounding the central core, the sealant for wrapping a solid electrode for heating and attachment to the central core;

the components for retaining the package are generally perpendicular to the interior of the furnace; and

- electrical components for generating an electric arc in the furnace, electrical components comprising a connection to the packaging.

Another object of the invention is to provide a process for forming a self-baking electrode in an electric arc furnace, the process comprising the steps of:

(a) procurement of an electrically conductive package with the top open;

b) positioning the longitudinal central core of the heat conducting material to the furnace and away from the package;

c) retaining the central core to the inner surface of the package to maintain the center within the package;

d) shifting the elongate electrically conductive wrapper in the furnace to expand generally perpendicularly;

e) introducing a certain amount of carbon electrode sealant into the envelope and surrounding the central core, the sealant is designed to wrap a solid electrode for heating and attachment to the central core;

f) coupling the package to a power source; and

g) generating by electric power to the electric power source of the electric arc in the furnace.

The central core of the electrode consists predominantly of carbon rods or rods connected to each other such that the heat transfer is in substantially continuous connection. Metal bars or rods may also be used.

However, the material used to produce the central core, such a core in the form of rods or rods, should be perforated to allow cooling by injection of biatomic or other gases. Thus, it is useful for controlling and influencing the electric arc on the electrode type and on the electrode firing.

In accordance with the invention, the packaging material is selected as being electrically conductive to transfer electrical energy from the contact tips to the Söderberg sealant to prevent unwanted metallic contamination or Ti, V, Ta, Cr, Zr or Ni. As an advantage, the casing can be made of Cu or brass, or an aluminum alloy or aluminum of sufficient strength to support the filling pressure of the Söderberg sealant without deformation or indentations.

Such selection makes the invention useful for producing suitable grade silicone metal for use in Rochow-direct synthesis. Indeed, it is only necessary to select the material forming the conductive core and the sheath support such that the resulting metal melting additions contain appropriate amounts of Al and / or Cu and / or zinc and / or tin as required in the silicone so produced.

As an advantage of the invention, the electrode allows the user to switch from the production of ferrosilicone using a conventional Söderberg electrode to produce silicone metal using the technology described without any downtime and since no other graphite core guiding devices are required, switching to Söderberg technology is possible and unique.

As appreciated, an important improvement in the electrode is that the central core of the electrode, which is attached to the sheath, is "deprived" of its function of transferring pressure forces to the extrusion as described for the electrode in the preferred art as indicated. Consequently, the core material is not subjected to the risk of bulging or deformation during indentation and also breakage. Furthermore, it eliminates the need for a separate sliding device, for performing the functions of the central core, and thus a substantial expense for irreversibly reassembling existing furnaces, with a carbon electrode prior to the firing carbon electrode as described. Furthermore, it permits a much safer use of the pierced electrode core, where, in the case of the extrusion principle, the presence of such a central hole in the central core weakens the core mechanically in cross-section, especially at plug or socket level.

An unbounded description of this preferred representation will be given with reference to the accompanying drawings.

Overview of the figures in the drawing

In FIG. 1 is a side elevational view schematically illustrating an electric arc furnace in which an electrode such as the present invention is used;

Fig. 2 is a side cross-sectional view of the electrode as a preferred representation of the invention illustrated by a conventional Söderberg electrode; and FIG. 3 is a cross-sectional view of the electrode of FIG. 2 taken along line II-II of FIG. Second

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an electric arc furnace 2 in which a self-baking electrode 4, such as the present invention, can be used as illustrated. The electric arc furnace 2 has a conventional design and can be used to melt, for example, ferrosilicon and silicone metal. As is well known, the furnace 2 comprises a body 6 itself made of a steel jacket and a suitable refractory material. The curtain 8 extends upward from the furnace and has an upper end provided with a lid 10 or furnace body 6. The electrode 4 extends perpendicularly inside the furnace body 6 through an opening 12 in the hatch 10. The furnace 2 comprises electrical components for generating an electric arc in the melting furnace 2 and a charge 14 in the furnace body 6 itself. The electrical components have a contact 16 connected to the electrode 4. The contact 16 is mounted on the electrode 4 with an ordinary semicircle 18. The furnace 2 may also be provided with a water-cooled jacket 20, for cooling the electrode 4, above the contact 16. The holding components are designed to retain the electrode 4 vertically. The holding components preferably comprise control cylinders 22 and two sliding belts 24 mounted on the top door 26 of the furnace and supporting the electrode 4.

As shown in Figures 2 and 3, the self-baking electrode 4 comprises an elongate electrical conductive casing open upwardly 30, for expansion in a generally perpendicular manner within the furnace body 2, in operation. The sheath 30 has an upper end 31 and a lower end 33. A central core 32 made of heat conductive material, predominantly made of carbon material, is disposed in the furnace and spaced from the package 30. The sheath 30 and the central core 32 define an annular channel 34 in which the carbon electrode sealant 36, predominantly Söderberg sealant, may be filled, fused and heated. In other words, a carbon electrode sealant 36 surrounds the central core 32, the sealant 36 is designed to wrap a solid electrode for heating and attachment to the central core 32.

The central core 32 may be in the form of a rod or other intended shapes and is held centrally within the shell 30 by at least one frame 37 that prevents relative displacement of the central core 32 relative to the shell 30 by being a sealant displacement between the core 32 and the shell 30 .

Preferably, the sheath 30 is made of thin-walled plain steel or thick-walled Dural in such a way that the strength of the walls can withstand the radial pressure of the Söderberg electrode sealant 36 as a filler. The filling of the sealant 36 into the electrode sheath 30 is done in a continuous manner so as to minimize the "decreasing" height as well as the total length between the contact tips.

In the case where the silicone metal is to be produced in the furnace 2, the container 30 is preferably made of a material unalloyed with a metal selected from the group consisting of titanium, vanadium, tantalum, chromium, zirconium and nickel to prevent contamination of the silicone metal to be produced. furnace 2, with one metal while the package is ingested in furnace 2.

More often in this case, the container 30 is made of a metal selected from the group consisting of copper, brass and aluminum.

As seen in FIG. 2 and 3, the frame 37 securing the central core 32 to the inner surface of the package 30 comprises a pair opposite the lying rods 38, each rod 38 generally laid horizontally having a first end 40 inserted into the central core 32 and a second end 42 secured to the inner surface of the package 30 The rod 44 penetrates through the central core 32 below the pair of rods 38, the rod 44 has opposing outer ends 46 projecting from the central core 32. The frame 37 further comprises two lateral frame 48, each connected to the other end 42 of each rod 38, k a corresponding outer end 46 of the rod 44. According to FIG. 3, two additional rods 60 may be provided to prevent distortion or rotation of the central core 32. Each of the rods 60 includes a first end 62 attached to the central core 32 and a second end 64 attached to the inner wall of the package 30, the two rods 60 contact the central cores 32.

Although not substantially, the expanded sheets 47 may be secured to the inner surface of the wrap 30 to better prevent the baking sealant 36 being forced downwards. However, experiments have shown that the frame 37 itself prevents the baking electrode 36 from being pushed down very effectively while the baking electrode is attached to the frame 37.

According to FIG. 2, an ordinary Söderberg electrode 49 is shown below the electrode 4 as the present invention. This common Söderberg electrode 49 comprises an outer shell 50 and a plunger 52 mounted on an inner wall of the shell 50. The self-baking electrode 54 is formed in the shell 50 and the electrode 54 and the shell 50 are moved downwardly. This type of electrode is well known in the art and does not need further description. As appreciated, this ordinary Söderberg electrode 49 should have the same diameter as the electrode 4 of the invention, showing that it is easy to move from the production of ferrosilicon, using a conventional Söderberg electrode 49, to the production of silicone metal, using the electrode of the invention , without any downtime or closure of the entire furnace.

The detailed structure of the electrode of the invention allows a large reduction in the volume of the metal, such as steel, which is normally used to prevent the self-baking electrode from being pushed down. In fact, with the electrode as of the invention, it is possible to obtain a silicone metal that contains less than 0.5% Fe, with a casing still made of steel.

Extensive studies of both the conventional electrode and the mixed electrode firing sample, where the electrode center is made of a solid material having substantially different thermal and electrical conductivity, have shown that when the electrode contains a high conductivity central core, the heating and firing sample is higher in the contact area. compared to conventional Soderberg technology. In more detail, the baking of the binder passes from the solid core of the conductivity of the large heat, compared to the surrounding Soderberg binder towards the sheath, unlike the conventional Soderberg electrode, the baking of the binder comes from the sheath and the plungers. Sôderbergovým material. The present invention uses in a well balanced system a high conductivity of the central core for the purpose of firing the surrounding Soderberg sealant 36. It does not need a relative displacement of the firing electrode 36 relative to its surrounding sheath 30 since this is the case with mixed electrodes known in the prior art and for use in manufacture silicone metal.

The method for producing a self-baking electrode 4 in an electric arc furnace 2 according to the present invention comprises the following steps.

(a) The elongated, open-ended, electrically conductive container is made.

b) The elongate central core 32 of the conductive thermal material is located within the furnace and away from the package 30.

c) The central core 32 is fixed to the inner surface of the container 30 and kept centered with the container 30.

d) The elongate electrically conductive casing 30 slides within the furnace 2 to expand generally perpendicularly.

e) A certain amount of carbon electrode sealant 36 is introduced in a package 30 surrounding the central core 32. The sealant 36 is designed to wrap a solid electrode for heating and attachment to the central core 32.

f) The electric arc is located in the furnace 2 according to a well known method which does not need further description.

Individually in step c), the central core 32 is secured to the package 30 by introducing the two opposite sides of the central core 32, the first end 40 of the matching rod 38, the pair opposite the lying rods 38 and securing the other end 42 of each, say, lying rods 38, to the inner surface of the wrapper so that each rod is usually drawn horizontally inside the wrapper 30. The rod 44 is inserted through the central core 32 below the two rods 38 in such a way that opposite the outer ends 46 of each rod 44 protrude from the central core 32. of each rod 38 is individually joined to a corresponding outer end 46 of the rod 44 with the structural lateral frame 48.

In the case where the electrode 4 is used to produce silicone metal, the sheath 30 in step d) may be advanced to the top of a previously produced Soderberg-type 49 self-baking electrode used to produce ferrosilicon, as shown in FIG. 2. In this case, the sheath 30 used to produce silicone may have substantially the same diameter as the outer sheath 50 of the Soderberg electrode 48. As mentioned above, it can be seen that it is easy to switch from ferrosilicon production by using a simple Soderberg electrode on producing a silicone metal using the electrode of the invention without stopping and shutting down the entire furnace.

Claims (5)

PATENT CLAIMS A self-baking electrode for producing silicone metal and silicone alloys for use in an electric arc furnace (2), comprising: - an open-ended elongated electrical conductive casing (30) extending perpendicular to the furnace (2) in operation, made of a non-alloyed metal material selected from the group consisting of titanium, vanadium, tantalum, chromium, zirconium and nickel to prevent contamination of the product to be manufactured in an oven with one of said metals while the package (30) is consuming in the oven (2); - a central core (32) located inside and spaced from the package (30), made of a heat-conducting carbon material; - in the package (30), at least one frame (37) for securing the central core (32) to the inner surface of the package (30), for centrally retaining the central core (32) in the package (30) and preventing the central core (32) downwards; and - a carbon electrode sealant (36) surrounding the central core (32) to wrap the solid electrode for heating and connection to the central core (32). The self-baking electrode of claim 1, wherein the central core (32) is made of interconnected carbon rods. The self-baking electrode according to claim 1 and 2, characterized in that the casing (30) is made of a metal selected from the group consisting of copper, brass and aluminum. A self-baking electrode according to claims 1 to 3, characterized in that the at least one frame (37) comprises: - a pair of opposing rods (38), each rod (38) disposed horizontally having a first end (40) inserted into the central core (32) and a second end (42) fixed to the inner surface of the package (30); - a rod (44) extending through the central core (32) below the pair of rods (38) having opposing outer ends (46) projecting from the central core (32); and - two lateral construction frames (48), each connecting the other end (42) of each rod (38) to the corresponding outer end (46) of the rod (44). The self-baking electrode of claim 1 to 4, wherein the central core (32) is pierced to inject cooling gases. An electric arc furnace (2) for producing silicone metal and silicone alloys, characterized in that it comprises: - a furnace body (6) for igniting the charge (14); - a self-baking electrode (4) containing: an open-ended elongate electrical conductive wrapper (30) having an upper end (31) and a lower end (33), the wrapper (30) being positioned perpendicularly in the furnace body (6) released to slide perpendicularly through the slide belts (24), the casing (30) is made of a non-metal-containing material selected from the group consisting of titanium, vanadium, tantalum, chromium, zirconium and nickel to prevent contamination of the product produced in the furnace with any of said metal while the casing (30) is consuming in the furnace ( 2); a central core (32) disposed within and spaced from the package (30) being made of a heat-conducting carbon material; at least one frame (37) with a sheath (30) for securing the central core (32) to the inner surface of the sheath (30) and for centrally holding the central core (32) in the sheath (30) and preventing the central core (32) down through the lower end (33) of the package (32); a central core (32) surrounded by a carbon electrode sealant (36) for wrapping a solid electrode for heating and attachment to the central core (32); retaining means comprising regulating cylinders (22) and sliding belts (24) of the casing (30) perpendicular to the furnace body (6); and electrical components for forming an electric arc comprising a contact (16) on the housing (30). An electric arc furnace according to claim 6, characterized in that the central core (32) is made of interconnected carbon rods. Electric arc furnace (2) according to claim 6 and 7, characterized in that the casing (30) is made of a metal selected from the group consisting of copper, brass and aluminum. Electric arc furnace (2) according to claims 6 to 8, characterized in that at least one frame (37) comprises: - a pair of opposing rods (38), each rod (38) being laid horizontally and having a first end (40) inserted into the central core (32) and a second end (42) fixed to the inner surface of the package (30); - a rod (44) penetrating through the central core (32) below the pair of rods (38) and whose opposing outer ends (46) protrude from the central core (32); and - two lateral construction frames (48), each connecting the other end (42) of each rod (38) to the corresponding outer end (46) of the rod (44). An electric arc furnace (2) according to claims 6 to 9, characterized in that the central core (32) is punched to inject cooling gases. Method for producing a self-baking electrode (4) for producing silicone metal and silicone alloys in an electric arc furnace (2), characterized in that it comprises the following steps: a) an open-ended longitudinal electrically conductive package (30) made of a material not alloyed with a metal selected from the group consisting of titanium, vanadium, tantalum, chromium, zirconium and nickel to prevent contamination of the product produced in the furnace with any of said metals during consumption a container (30) in the furnace (2); b) placing the central core (32) of carbon heat conducting material in the furnace and away from the package (30); c) securing the central core (32) to the inner surface of the package (30) and keeping it centrally in the furnace (30); d) slipping the perpendicularly elongated electrically conductive wrapper (30) in the furnace (2); e) introducing a carbon electrode sealant (36) into the shell, wherein the central core (32) is surrounded by the sealant (36), the sealant wrapping an electrode for heating and connection to the central core (32); and f) connecting the package (30) to a power source; and g) forming an electric arc in the furnace (2) with the electric power source. The method of claim 11, wherein step c) comprises the following steps: - introducing individually the two opposite sides of the central core (32) of the first end (40) of the matching bar (38) with the pair opposite the lying bars (38) and securing the second end (42) of each of the opposite bars (38) to the inner surface of the package (30), wherein each rod (38) is disposed horizontally in the package (30); - inserting the rod (44) through the central core (32) beneath the two rods (38), wherein the opposing outer ends (46) of the rod (44) protrude from the central core (32); and - interconnecting with a respective lateral frame (48), with a second end (42) of each rod (38) to a corresponding outer end (46) of the rod (44). Method according to claim 12, characterized in that: - in step d), the sheath (30) is connected to the top of a Söderberg-type self-baking electrode (49) used to produce ferrosilicon, wherein the Soderberg electrode (49) comprises an outer sheath (50), and wherein - the electrode sheath (30) which is shaped has substantially the same diameter as the outer sheath (50) of the Söderberg electrode (49).