DE102011079967A1 - Coated blast furnace stones - Google Patents

Abstract

The invention relates to a carbon brick for lining, in particular inner lining, of melting and reduction furnaces, in particular blast furnaces, which has a surface, wherein a portion of the surface provides a process side of the carbon stone, the normal use of the carbon stone with liquid metal, in particular pig iron, and or slag is brought into contact and the carbon brick has a carbon material containing body having a surface. The invention is characterized in that, for the provision of the process side of the carbon brick, a protective coating is applied to at least a region of the surface of the base body, which comprises or is formed from a ceramic covering coating reducing the wear.

Description

The present invention relates to a carbon brick for the inner lining of melting and reduction furnaces, a melting and reducing furnace containing such a carbon brick and a method for producing such a carbon brick. In particular, these melting and reduction furnaces blast furnaces for the production of pig iron.

For example. have melting and reduction furnaces designed as blast furnaces several superimposed zones, wherein in the so-called melting zone, prevail in the temperatures in the range of about 1600 ° C, the molten pig iron and slag is.

Inner linings of smelting and reduction furnaces are often made in the region of the melting zone of carbon stones, which are usually constructed essentially of amorphous and / or graphitic carbon material and / or graphite.

The carbon stones in contact with the molten metal, eg pig iron, and the slag are subject to high chemical and mechanical wear, for example, caused by the solubility of the carbon in carbon-unsaturated pig iron, the penetration of metal, for example, pig iron into the pore system of Carbon stones, which causes cracks in the stones, by movement of the molten metal, for example, pig iron, and the slag and by reaction of the carbon with slag constituents and / or alkalis.

The above-mentioned wear mechanisms significantly reduce the life of carbon bricks in melting and reduction furnaces. For example, in order to be economical, melting and reduction furnaces designed as blast furnaces should be able to operate for 15 years or more without major repairs. By premature wear even only some of the carbon stones in the melting zone but the life of the entire melting and reduction furnace is limited, resulting in a premature end of the furnace travel and thus reduced furnace efficiency. Therefore, carbon blocks must have a long service life at all positions in the furnace where they are used - even in the area of the highly stressed melting zone.

In the past, attempts have been made to improve the service life of carbon bricks for the inner lining of melting and reducing furnaces formed as blast furnaces, for example, by adhering ceramic tiles to the carbon bricks on the process side in contact with the molten pig iron. Such solutions are for example from the US2005 / 025443 and the EP1975258 where silicon carbide or alumina tiles are adhered to the carbon body and provide the process side of the carbon brick. However, these solutions are complicated by the additional bonding step and therefore expensive. Furthermore, under the prevailing conditions, an adhesive bond is not permanently stable, as a result of which the tiles detach from the carbon base bodies, which significantly reduces the desired protective effect.

The solutions proposed in the past have not led to a satisfactory increase in the life of carbon stones for the inner lining of melting and reduction furnaces and were often also expensive to produce.

The object of the present invention is therefore to propose a carbon brick for the inner lining of melting and reduction furnaces, which has an increased wear resistance.

The object of the invention is also to propose a melting and reduction furnace with extended life.

The object of the invention is also to propose a method for the cost-effective production of a wear-resistant carbon stone for the inner lining of melting and reduction furnaces.

The above objects are achieved by the features of independent claims 1, 12 and 15.

The idea of the invention is to increase the wear resistance of carbon bricks to the inner lining of melting and reduction furnaces in a reliable and cost-effective manner by applying to the surface of the base body in the region containing the molten metal, in particular pig iron, and / or to provide the slag with the process side in contact, a protective coating comprising a wear reducing ceramic topcoat is applied.

A coating is to be understood in this patent application at least one layer which is formed by applying a formless material on a substrate and firmly connected to the substrate.

By providing a protective coating comprising a ceramic top coat, the carbon material of the base body, and thus the carbon stone, can be effectively and inexpensively protected from wear in the melting and reduction furnace.

Advantageous embodiments and further developments of the invention are specified in the subclaims.

For the purposes of the present invention, amorphous carbon is understood as meaning a carbon material which contains anthracite and / or coke and not more than 70% by weight of graphite and which was exposed in its entirety to a temperature of 2000 ° C. or less.

For the purposes of the present invention, graphitic carbon is understood as meaning a carbon material which contains more than 70% by weight of graphite and which was exposed in its entirety to a temperature of 2000 ° C. or less.

Within the meaning of the present invention, graphite is understood as meaning synthetic graphite or natural graphite or a mixture thereof.

If in the context of the present patent application of a blast furnace is talking, a blast furnace for the production of pig iron is to be understood.

However, there are also other melting and reduction furnaces which may be included in the invention. These may, for example, melting and reduction furnaces for the production of ferroalloys, such as ferro-silicon, ferro-manganese, ferro-chromium, ferro-nickel, special alloys (including FeV, FeNb, FeW, FeMo), and for the production of non-ferrous alloys such Calcium carbide and calcium silicon act. The aforementioned ovens, which are not blast furnaces, are also referred to as so-called "Submerged Arc Furnaces" (SAF).

According to a particularly preferred embodiment of the invention, it is provided that the protective coating additionally comprises an intermediate coating arranged between the surface of the main body and the top coat, which has a thermal expansion in the temperature range from 20 ° C to at least 1600 ° C, which is between the thermal expansion of Body and the ceramic top coat is.

By this preferred embodiment, the formation of cracks in the protective coating and the resulting flaking of the protective coating can be reduced, if not prevented, since high thermal stresses in the cover coating which comes into contact with the metal, for example pig iron, are reduced or even prevented.

Since a main body constructed essentially of carbon material usually has a lower thermal expansion in the temperature range from 20 ° C. to at least 1600 ° C. than a ceramic material suitable for the top coat, which is resistant to mechanical and chemical wear by molten metal, in particular pig iron, and / For example, at 1000 ° C., carbon materials may have a thermal expansion coefficient of about 3 × 10 ^-6 / K, whereas, for example, aluminum oxide has a thermal expansion coefficient of about 8.5 × 10 ^-6 / K at this temperature In the case of a protective coating without an intermediate coating, high thermal stresses can occur during operation which can lead to cracking in the top coating and thus to its premature failure. In the present embodiment, the intermediate coating serves as a buffer between the divergent thermal expansion behavior of carbon body and topcoat.

By the preferred embodiment, it is also possible to produce an optimal connection of the protective effect against the wear of molten metal, in particular pig iron, and slag providing top coat and the body and also to select the material for the top coat optimally to the specific task of protection.

• – höhere Beständigkeit gegen flüssiges Metall, insbesondere Roheisen,
• – höhere Beständigkeit gegen Alkalien,
• – höhere Stabilität gegen oxidierende Atmosphäre,
• – höhere Beständigkeit gegenüber mechanischem Verschleiß
• – Geringere Infiltration von flüssigem Metall, insbesondere Roheisen,
• – Stärkere Bildung einer „natürlichen” Schutzschicht aus anhaftendem Metall, insbesondere Roheisen, und/oder Schlacke

The top coat is preferably selected such that it fulfills at least one, preferably several and particularly preferably all of the following functions with respect to a carbon brick, which, except for the absence of the protective coating, is constructed identically to the carbon brick according to the invention:

• Higher resistance to liquid metal, in particular pig iron,
• - higher resistance to alkalis,
• - higher stability against oxidizing atmosphere,
• - higher resistance to mechanical wear
• - less infiltration of liquid metal, in particular pig iron,
• Stronger formation of a "natural" protective layer of adherent metal, in particular pig iron, and / or slag

• – gute Anbindung an die Oberfläche des Grundkörpers
• – gute Anbindung an die Deckbeschichtung
• – dauerhafte Einsetzbarkeit bei Temperaturen bis zumindest 1600°C, d. h. beispielsweise keine Gefügeänderungen, keine Phasenübergänge

The intermediate coating is preferably selected so that these - in addition to their thermal expansion in the Temperature range of 20 ° C to at least 1600 ° C between that of the body and the top coat is at least one, preferably more and more preferably all of the following functions:

• - good connection to the surface of the body
• - good connection to the topcoat
• - Permanent applicability at temperatures up to at least 1600 ° C, ie, for example, no structural changes, no phase transitions

A further particularly preferred embodiment of the invention provides that the protective coating is formed only from the intermediate coating and the top coat, d. H. According to this embodiment, the protective coating comprises no further coatings than the intermediate coating and the topcoat. In this connection, provision is made in particular for the intermediate coating to be applied directly on the surface of the main body and the ceramic topcoat directly on the intermediate coating.

In principle, it would be possible to provide the entire surface of the base body with the protective coating. But this is not necessary and often not desired, since the protective coating on the one hand brings with it additional costs and on the other to surface sections where it is not needed, such as the top or the bottom of the carbon stone, where the stones for training the inner lining are stacked vertically, is more of a hindrance. A preferred development of the invention therefore provides that the carbon brick has the protective coating only in the region of its surface which provides the process side.

It is also conceivable that the carbon brick is provided in addition to the process side on the opposite side of the process side of its surface with the protective coating. This is particularly useful when the carbon stone is arranged in the region of the tap hole of the furnace formed as a blast furnace and reduction, since in this area liquid pig iron is tapped and from the interior of the furnace to the outside, the so-called. Cold side occurs. As a result, the cold side of the furnace comes into contact with the molten pig iron and is thus subject to high wear. By providing the coating of the carbon brick both on its process side and on its side providing the outside of the furnace, the wear previously described can thus be reduced.

If the carbon brick comprises a tap hole, a further preferred embodiment of the invention provides that the interior of the tap hole itself has the protective coating already described. In principle, it is conceivable for the intermediate coating to be formed by one or more intermediate layers. Furthermore, it is conceivable in principle that the ceramic cover coating is formed by a single or by a plurality of ceramic cover layers. In this context, various combinations are possible. Thus, it is possible that both the top coat and the intermediate coat are each formed of only a single coat. It is also conceivable that the intermediate coating of a single layer and the top coat are formed of several layers. Further, it is possible that the top coat is formed of a single layer and the intermediate coat of multiple layers. In addition, it can also be considered that both the top coat and the intermediate coat are each formed from several layers.

The ceramic topcoat may include or be formed from one or more oxidic or carbidic or more carbidic or boridic or more boridic or nitricidal or more nitridic ceramic materials or mixtures thereof. Further, the intermediate coating may contain or be formed from one or more metals or one or more oxidic or carbidic or more carbidic or boridic or more boridic or nitridic or more nitridic ceramic materials or mixtures thereof.

In this context, it is both possible that a cover layer of the top coat consists of a mixture of the above-mentioned materials as it is also possible, for example. In the case that the top coat is composed of several cover layers is possible that a cover layer of the top coat only one of the consists of the above materials and another cover layer of the top coat of another of the above materials or of several of the above materials.

The above considerations apply to the same extent for the intermediate coating, in which both an intermediate layer of only one or more of the above materials may be formed or may contain these materials, as it is also possible that an intermediate layer consists of only one material whereas another intermediate layer consists of several of the above-mentioned materials. Furthermore, can be provided that the intermediate coating is formed of a single or multiple metals.

Accordingly, it can be provided that at least one intermediate layer is formed from a single material and / or at least one cover layer is formed from a single material.

An exemplary and non-exhaustive list of possible concrete embodiments for the intermediate coating and the top coat provides, for example, that the intermediate coating of a single layer of molybdenum and the top coating of a single layer of alumina are formed. It is also conceivable in this connection that the intermediate coating is formed from a single layer of aluminum nitride and the top coating is formed from a single layer of titanium carbide. Further, it is also possible, for example, for the intermediate coating to consist of a single layer of tungsten carbide and the topcoat of a single layer of titanium diboride.

Preferably, the topcoat has a thickness in the range of 50 microns to 1500 microns, preferably 100 microns to 1000 microns, more preferably 400 microns to 700 microns. Experiments have shown that from layer thicknesses of more than 1500 microns to thinner layer thicknesses no improvement in the protective effect more occurs, but rather a deterioration, since topcoats with such high layer thicknesses tend more to cracking than thinner. Furthermore, tests have shown that topcoats with layer thicknesses from 400 μm already provide sufficient wear protection.

Preferably, the intermediate coating has a layer thickness in the range of 10 .mu.m to 600 .mu.m. In the case that the intermediate coating consists of several intermediate layers, the individual intermediate layers can each have a layer thickness in the range of 10 .mu.m to 200 .mu.m.

The carbon material of the main body preferably contains or is preferably formed from, amorphous carbon such as anthracite and / or coke, graphitic carbon, synthetic graphite, natural graphite or a composition of several of the aforementioned materials. Further, in addition to the carbon material, the material composition of the base body may contain one or more ceramic constituents, the proportion of all ceramic constituents being lower in the material composition than the proportion of the carbon material. The material composition preferably contains more than 60% by weight of the carbon material. As ceramic constituents, for example, one or more oxidic (s), one or more carbidic (s), one or more nitridic (s), one or more boride (s) ceramic material (s), or mixtures of several of the aforementioned materials are possible.

In accordance with a further aspect of the invention, a melting and reducing furnace, in particular a blast furnace, designed as a shaft furnace, having a melting zone in which molten metal, in particular pig iron, and / or slag is present during operation of the furnace, is proposed. The shaft furnace has an inner furnace lining, which is in contact with the molten metal, in particular pig iron, and / or the slag during operation of the furnace in the region of the melting zone. According to the further aspect of the invention, it is proposed that the inner furnace lining at least in the region of the melting zone contains at least one carbon block according to the invention, which points with its process side into the interior of the shaft furnace.

In the area of the tap hole, liquid pig iron and / or slag is tapped off and exits from the so-called cold side of the furnace from the melting and reduction furnace designed as a blast furnace. As a result, the cold side of the furnace comes in contact with the liquid pig iron and / or the slag in the region of the taphole, whereby the carbon blocks arranged in this region come into contact with the liquid pig iron and / or the slag on the cold side. In order to reduce the resulting wear on the cold side, a preferred embodiment of the invention provides that in the region of the at least one taphole at least one further inventive carbon stone is provided with its process side at least partially the outside or cold side of the furnace in the Provides the tap hole area. According to this embodiment, the furnace therefore has a plurality of carbon stones according to the invention, of which at least one with its coated process side provides the inside of the furnace and at least one with its coated process side the outside of the furnace.

According to an alternative embodiment to the above-mentioned embodiment, at least one carbon brick, in addition to the coating on the process side, at least partially has a protective coating on a cold side of its surface opposite the process side, and in that the at least one carbon brick is arranged in the region of the taphole, the coated process side faces inside the furnace and is in contact with the molten pig iron and the coated cold side provides part of the outside of the furnace in the region of the tap hole. Preferably, in this case the protective coating forming part of the outside of the furnace is the same as the one Protective coating of the carbon brick of the process side built up.

• – Herstellung einer Mischung die mehrere Bestandteile enthält, ausgewählt aus der Gruppe der Anthrazite, Kokse, Graphite, metallische oder keramische Additive, Bindemittel aus der Gruppe der Teere, Peche, Bitumen,
• – Formgebung der Mischung zum Erhalt eines Grünkörpers,
• – Brennen und optional nachfolgend Imprägnieren und/oder Graphitieren des Grünkörpers zum Erhalt eines Kohlenstoffkörpers,
• – Mechanisches Bearbeiten des Kohlenstoffkörpers zum Erhalt eines Grundkörpers des Kohlenstoffsteins mit einer Oberfläche
• – Aufrauen der Oberfläche des Grundkörpers zumindest in dem Abschnitt, der eine spätere Prozessseite des Kohlenstoffsteins bereitstellen soll,
• – Aufbringen einer Schutzbeschichtung auf zumindest einen Abschnitt der aufgerauten Oberfläche.

According to a third aspect of the invention, a method is proposed for producing a carbon brick for the inner lining of melting and reducing furnaces, comprising the following steps:

• Preparation of a mixture containing a plurality of constituents selected from the group of anthracites, cokes, graphites, metallic or ceramic additives, binders from the group of tars, pitches, bitumen,
• Shaping the mixture to obtain a green body,
• Firing and optionally subsequently impregnating and / or graphitizing the green body to obtain a carbon body,
• - Machining the carbon body to obtain a body of carbon with a surface
• Roughening the surface of the base body at least in the section intended to provide a later process side of the carbon stone,
• Applying a protective coating to at least a portion of the roughened surface.

The shaping can be done for example by vibration compression (vibromolding) or extrusion. The firing of the green body can be carried out at temperatures in the range of about 800 ° C to 1300 ° C.

The metallic additives may be, for example, silicon (Si), titanium (Ti) or zirconium (Zr), which are at least partially converted into a ceramic material in the subsequent firing and / or graphitization process. The ceramic additives may, for example, be silicon carbide (SiC), titanium dioxide (TiO ₂ ) or aluminum oxide (Al ₂ O ₃ ) or aluminum silicates. According to a preferred embodiment of the method according to the invention, the protective coating is applied by first applying an intermediate coating to at least one area of the roughened surface and subsequently applying a topcoat to at least one area of the intermediate coating.

The surface to be coated of the carbon body obtained after the firing process and the mechanical processing can be roughened by sand blasting, for example. Methods for applying the intermediate layer and the cover layer may be, for example, methods such as plasma spraying, flame spraying, chemical vapor deposition (CVD), physical vapor deposition (PVD) or the like.

In this context, it is, for example, conceivable that a suspension is provided for the production of the ceramic topcoat and / or the intermediate coating, which is applied, for example, by a coating, spraying or dipping process on the area of the surface of the base body to be coated and below for the conversion of the suspension in the topcoat or the intermediate coating is subjected to a temperature treatment. The suspension may in this case, for example, contain a polymeric liquid and ceramic particles.

The invention will be explained below with reference to two drawings. It show the

1 an embodiment of a carbon brick according to the invention in side view,

2 a reduction and melting furnace according to the invention in longitudinal section.

The 1 shows a carbon stone 1 for the inner lining of melting and reduction furnaces. The shown carbon stone 1 has a surface 2 on a section of a process page 3 of the carbon stone 1 provides. The process page 3 is when the carbon stone is used as intended 1 contacted with molten metal, in particular pig iron, and / or slag.

The illustrated carbon stone 1 has a body containing carbon material 4 with a surface 5 on the to provide the process page 3 in one area 5 ' a protective coating 6 is applied. The protective coating shown in the present embodiment 6 is by a wear-reducing ceramic topcoat 7 and one between the surface 5 of the basic body 4 and the topcoat 7 arranged intermediate coating 8th educated.

In the present case are the intermediate coating 8th as well as the ceramic topcoat 7 each formed by a single layer, wherein the intermediate coating 8th forming intermediate layer of the metal molybdenum and the topcoat 7 forming covering layer of the ceramic is alumina.

The intermediate coating 8th and the topcoat 7 are tuned so that in the temperature range of 20 to at least 1600 ° C, the thermal expansion of the intermediate coating 8th is greater than the thermal expansion of the body 4 and smaller than the extension of the ceramic topcoat 7 ,

In the present case are the intermediate coating 8th directly on the surface 5 of the basic body 2 and the ceramic topcoat 7 directly on the intermediate coating 8th applied. The topcoat 7 of the present embodiment has a thickness of about 500 microns and the thickness of the intermediate coating 8th is about 100 microns.

In the present case is the basic body 4 from a mixture containing about 40% by weight of anthracite, about 40% by weight of graphite, about 10% by weight of silicon and about 10% by weight of aluminum oxide in the dry mixture, the product produced therefrom Green body for the production of the carbon body was fired at about 1200 ° C.

In the present embodiment, the carbon brick is only in the process side 3 providing section of its surface 2 with the protective coating 6 Mistake.

The 2 shows a reduction and melting furnace according to the invention 9 , which is designed in the present embodiment as a blast furnace in manhole construction.

In a blast furnace pig iron is obtained by reduction from iron ores, with the coke being mainly used as energy carrier and reducing agent and various additives such as quartz sand, lime being added to form slag and lower the melting temperature. The blast furnace 9 has a rest in its lower part 10 and one as a frame 11 designated section, in this case the melting zone 12 the blast furnace 9 surround. In the melting zone 12 is in operation molten pig iron and slag. This prevails in the melting zone 12 a temperature in the range of about 1600 ° C. During operation, hot air is released via so-called tuyeres 13 in the melting zone 12 blown through a loop 14 be supplied. The slag gets over a tap hole 15 and the pig iron gets over a tap hole 16 from the melting zone 12 guided. At the illustrated blast furnace 9 is the entire melting zone 12 enclosing inner lining, ie the directed into the furnace interior side at least partially, preferably completely from the carbon stones according to the invention 1 built up.

Furthermore, in the area of the two tap holes 15 and 16 the outside of the blast furnace 9 forming outer wall at least in sections by carbon blocks according to the invention 1 formed with their process page 3 the outside of the blast furnace in the area of the tap holes 15 and 16 provide.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2005/025443 [0006]
• EP 1975258 [0006]

Claims (16)

Carbon brick for lining, in particular interior lining, of melting and reducing furnaces, in particular blast furnaces, the carbon brick having a surface and a region of the surface providing a process side of the carbon brick which, when the carbon brick is used with liquid metal, in particular pig iron, and / or slag and the carbon brick has a carbon body-containing base body having a surface, characterized in that for providing the process side of the carbon stone at least on a region of the surface of the base body, a protective coating is applied, which comprises a wear-reducing, ceramic cover coating or from it is formed. Carbon stone according to claim 1, characterized in that the protective coating additionally comprises an intermediate coating arranged between the surface of the base body and the top coat, which has a thermal expansion in the temperature range from 20 ° C to at least 1600 ° C, that between the thermal expansion of the base body and which is the ceramic topcoat. Carbon stone according to claim 1 or 2, characterized in that the intermediate coating is applied directly on the surface of the base body and the ceramic cover coating directly on the intermediate coating. Carbon stone according to one of claims 1-3, characterized in that the protective coating is formed of the intermediate coating and the top coat. Carbon brick according to one of claims 1-4, characterized in that in the temperature range of 20 ° C to at least 1600 ° C, the thermal expansion of the intermediate coating is greater than the thermal expansion of the body and smaller than the thermal expansion of the ceramic topcoat. Carbon brick according to any one of claims 1-5, characterized in that the ceramic topcoat one or more oxidic (s), one or more carbidic or one or more boridic (s) or one or more nitridic (s) ceramic material or Contains or is formed from ceramic materials or mixtures and / or that the intermediate coating comprises one or more metallic material (s) or one or more oxidic, one or more carbidic, one or more boridic or one or more nitridic ceramic material or ceramic materials or mixtures thereof or is formed therefrom. Carbon brick according to one of claims 1-6, characterized in that the topcoat has a thickness in the range of 50 microns to 1500 microns, preferably 100 .mu.m to 1000 .mu.m, more preferably 400 .mu.m to 700 .mu.m. Carbon brick according to any one of claims 1-7, characterized in that the intermediate coating has a thickness in the range of 10 microns to 600 microns, and in the case that the intermediate coating of a plurality of intermediate layers, the individual intermediate layers each have a thickness in the range of 10 microns to 200 microns have. Carbon brick according to any one of claims 1-8, characterized in that the carbon material of the body contains amorphous carbon or graphitic or graphitized carbon or a mixture thereof. A carbon brick according to claim 9, characterized in that the base body contains, in addition to the carbon material, one or more ceramic constituents which together with the carbon material form a material composition and are present in the material composition to a lesser extent than the carbon material. Carbon brick according to any one of claims 1-10, characterized in that the carbon stone has the protective coating only in the process side providing portion of its surface. As a shaft furnace formed melting and reduction furnace, in particular blast furnace, which has a melting zone in which molten metal, in particular pig iron, and / or slag is in operation of the furnace, and with an inner furnace lining, which in the operation of the furnace in the region of the molten zone with molten metal, in particular pig iron, and / or slag is in contact, characterized in that the inner furnace lining contains at least in the region of the melting zone at least one carbon stone according to one of claims 1 to 11 and points with its process side into the interior of the shaft furnace. Melting or reduction furnace according to claim 12, characterized in that the furnace has at least one tap hole through which the molten metal, in particular pig iron, and / or the slag can be led from the molten zone to the outside of the furnace, wherein in the region of at least a tapping hole at least one more carbon stone after one of Claims 1 to 11 is provided, which at least partially provides the outside of the furnace in the region of the tap hole with its process side. Melting or reducing furnace according to claim 12, characterized in that the furnace has at least one taphole through which the molten metal, in particular pig iron, and / or the slag can be led from the molten zone to the outside of the furnace, that at least one carbon brick, in addition to the coating on the process side, on at least one side of the process side cold side of its surface has a protective coating and that the at least one carbon stone in the tap hole is arranged so that the coated process side inside the furnace and the coated cold side has a Part of the outside of the furnace in the area of the tap hole provides. Process for the production of a carbon brick for the inner lining of melting and reduction furnaces, the process comprising the following steps: a. Preparation of a mixture containing a plurality of constituents selected from the group of anthracites, cokes, graphites, metallic and / or ceramic additives, binders from the group of tars, pitches, bitumen, b. Shaping the mixture to obtain a green body, c. Burning and optionally subsequently graphitizing the green body to obtain a carbon body, d. Machining the carbon body to obtain a body of carbon with a surface e. Roughening the surface of the body at least in the portion intended to provide a later process side of the carbon stone, f. Applying a protective coating to at least a portion of the roughened surface A method according to claim 15, characterized in that the protective coating is applied by a. first an intermediate coating on at least a portion of the roughened surface and  b. subsequently applied to at least a portion of the intermediate coating of a topcoat.

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