Title of Invention	LARGE VOLUME INDUSTRIAL FURNACE
Abstract	in which mineral products, e.g, cement, Lime, magnesite, dolomite or the like, are fired in an essentially oxidizing furnace atmosphere at temperatures above 700"C, wherein the masonry is composed of unfired bricks of refracted material and carbon is present in the fire-side or hot-side surface region of the bricks of the masonry. In addition, the invention relates to refractory bricks for producing the masonry.

Title of Invention

LARGE VOLUME INDUSTRIAL FURNACE

Abstract

in which mineral products, e.g, cement, Lime, magnesite, dolomite or the like, are fired in an essentially oxidizing furnace atmosphere at temperatures above 700"C, wherein the masonry is composed of unfired bricks of refracted material and carbon is present in the fire-side or hot-side surface region of the bricks of the masonry. In addition, the invention relates to refractory bricks for producing the masonry.

Full Text	Refractory wall and refractory bricks for building said wall 5 The invention relates to refractory masonry and refractory bricks for producing the refractory lining of large-volume industrial furnaces in which mineral products such as cement, lime, magnesite, dolomite or the like are fired under an essentially oxidizing 10 atmosphere at temperatures above 700oC, in particular above 900°C. In industry, cement, line, magnesite and dolomite are mainly fired in rotary tube furnaces or shaft kilns. 15 The firing process is essentially carried out under oxidizing conditions. The operating life of the furnaces depends, inter alia, on the type of refractory masonry lining which, 20 firstly, protects the metal outer wall of the furnace from the high temperatures of the material being fired, flame temperatures and atmospheric temperatures and, secondly, reduces heat losses. In addition, the refractory lining can act as a heat exchanger which 25 takes up the heat energy from the hot furnace gases and passes it to the material being fired. The masonry lining of the furnace is usually subjected to high temperature-change stresses and high mechanical 30 and chemical stresses- The temperature-change stresses result from the higher temperature of the furnace gases compared to the temperature of the material being fired. Mechanical stresses are caused by rotary motion of the furnace and by movement of the material being 35 fired. The masonry is subjected to chemical stresses by - 1a - constituents of the material being fired and by volatile compounds in the furnace atmosphere which deposit in the refractory lining as a result of temperature gradients. — 2 — These furnaces which are operated under oxidizing conditions, e.g. rotary furnaces for cement and lime, furnaces for dolomite and magnesite and shaft kilns, are lined with fired refractory bricks, in the basic 5 region essentially with refractory bricks based .on Mgo, e.g. with magnesia spinel bricks, magnesia chromite bricks, magnesia hercynite bricks as magnesia spinel mineral bricks, magnesia zirconia bricks, dolomite bricks ox the like and in the nonbasic region with 10 chamotte bricks, andalusite bricks, bauxite bricks or the like. The lining is occasionally also constructed using unfired phosphorus- or phosphate-bonded lightweight 15 refractory bricks in some zones. For the purposes of constructing the masonry, the furnaces are divided into various zones because different stresses occur in the zones during operation. 20 In the case of a rotary tube furnace for cement, the furnace is divided, going from the feed end for the material being fired to the outlet end for the material being fired, into, for example, a preheating zone, a safety zone, an upper transition zone, a sintering 25 zone, a lower transition zone and an outlet zone. A stable accumulation of material being fired is generally formed in the sintering zone, and this can protect the sintering zone. Detachment of material from this accumulation can cause damage, as can cement 30 clinker phase infiltration in the event of overheating. If the accumulation is absent or unstable, the transition zones are subjected to alkali Infiltration, thermal influences and redon influences and also temperature changes. In addition, thermomechanical 35 stresses occur, for example, as a result of ovality stresses and curvature of the furnace axis. Secondary fuels, e.g. automobile tires, also produce additional uncontrollable stresses. - 2a - The preheating, safety and outlet zones are generally lined with bricks which are rich in chamotte and alumina, while the other zones are generally lined with bricks based on magnesia (MgO) or dolomite (MgO/OaO). 5 Shaft kilns are generally divided similarly. - 3 - When operating conditions are uniform, the known furnace linings provide the prescribed properties and protect against premature attrition. However, uniform operating conditions can often not be achieved. Changes 5 in furnace operating parameters or materials parameters, e.g. in respect of clinker moduli in the firing of cement or necessary repair of previous damage is not carried out in good time, frequently occur within a relatively short time. Changing chemical 10 attacks and changing thermal and thermomechanical stresses lead to accelerated attrition and to damage. Attempts have been made in the past to counter this problem by improving the materials composition of the 15 fired bricks and thus to match them to unfavorable operating conditions. This application-oriented optimization comprises essentially changing the chemical-mineralogical composition of the bricks with the aim of, for example, increasing their elastic 20 properties and corrosion resistance. An example is provided by magnesia spinel bricks which generally ensure a higher elasticity than magnesia chromite bricks. In addition, the magnesia chromite bricks are subject to higher corrosion due to attack by cement 25 clinker phases. This is countered by means of magnesia zirconia bricks which are less stress-sensitive. Accordingly, these bricks have been developed further and special bricks designed for the respective stress case have been produced. However, since the stress 30 cases are varied, this development leads to a dead end and is very costly. It is an object of the invention to provide refractory masonry for furnaces operated using an oxidizing 35 furnace atmosphere, which survives stress changes significantly better and whose refractory brick material is optimally matched to the normal stresses and not to the stress changes. - 3a - This object is achieved by the features of claim 1, Advantageous embodiments of the invention are defined in the subordinate claims. - 4 - According to the invention, unfired refractory bricks composed of customarily used material, e.g. one of the abovementioned refractory materials, which have customarily used three-dimensional shapes and are 5 phosphorus-bonded or whose binder is a synthetic resin, tar or pitch or are bonded by means of another suitable material are employed. It is important that carbon, particular graphite, is 10 present in the brick material, in particular in the pores, on the side of the masons or the bricks facing the interior of the furnace. The graphite can be a natural or synthetic graphite, e.g. floe graphite. It has been found that the graphite together with the 15 material being fired and/or the oxidizing atmosphere in all zones obviously produces a type of sealing of the surface of the unfired bricks which not only does not disturb the desired optimised properties in respect of the different stresses in the zones but also ensures 20 the prescribed properties in the case of stress changes. The graphite is particularly effective in combination with a carbon-containing binder material such as synthetic resin, tar or pitch, with the action being particularly good when synthetic resin is 25 present. Synthetic resins are used, in particular phenolic resins (phenol resol) or phenolic resin- novalak solutions. It is advantageous to provide a graphite-containing 30 zone of from about 1 to 18 cm, preferably from 2 to 15 cm, which makes the graphite available for the oxidizing surface reaction with the material being fired and/or the furnace atmosphere, and may additionally provide a reserve stock of graphite and, 35 if appropriate, carbon-containing binders in the interior of the brick. The sealing zone obviously protects the furnace-side (hot-side) surface region of the bricks so that not all of the graphite from the graphite-containing zone is consumed and is available - 4a - for further sealing in the event of damage to the surface. - 5 - The porosity in the graphite-containing zone, but preferably also in the entire unfired brick, is advantageously less than 30% by volume, preferably less than 14% by volume, in particular, the porosity is in 5 the range from 1 to 8% by volume. The graphite content of the graphite-containing zone is preferably from 2 to 30% by weight, in particular from S to 20* by weight. In the case of carbon-containing 10 binders, the carbon content of binder plus grapftite should be within the indicated limits of from 2 to 30% by weight, in particular from 5 to 20% by weight. The carbon-containing binder is preferably used in amounts of from 2 to 5% by weight, in particular from 2-5 to 4% 15 by weight. In a particular embodiment of the invention, the graphite-containing zone . further comprises antioxidants, for example AL, si, mg, sic, Si3N4, B4C or 20 metallic alloys. The antioxidants surprisingly do not adversely affect the formation of the soaling zone on the surface, but prevent excessively deep penetration of the oxidation into the graphite-containing zone, so that carbon, reserves remain for future reformation of 25 damage to sealing regions. The use of bricks which are completely graphite- containing or graphite-containing in their entirety or throughout is encompassed by the scope of the 30 invention. It is likewise within the scope of the invention, in particular, to use bricks which are completely graphite-containing and are bonded by carbon-containing binders such as synthetic resin, tar or pitch. In this respect, the invention provides for 35 the use of basic, carbon-containing refractory bricks known per se which have been designed for use in a reducing a-atmosphere, e.g. for use in steel production, for the masonry of furnaces operated under oxidizing conditions. Such basic refractory bricks are used, for - 5a - example, for lining metallurgical vessels such as converters, steel pouring ladles or electric are- furnaces. These likewise unfired carbon-containing bricks, in particular magnesia bricks or dolomite - 6 - bricks, ensure compatibility with most basic slags and the stability of the carbon, in particular the graphite too, in the reducing atmosphere which prevails in steel production. The bricks are bonded by means of synthetic 5 resin, pitch or tar and are shaped in the cold state (phenolic resin-bonded or phenolic resin-novalak-bonded bricks) or in the hot state (phenolic resin-novalak It- bonded or tar- or pitch-bonded bricks) . In addition, the bricks generally further comprise antioxidants 10 which, owing to their higher affinity for oxygen compared to carbon, reduce burning away of the carbon. The action of the antioxidants is based mainly on their making entry of gas more difficult and on an increase in the strength- Materials typically used are metals, 15 carbides or nitrides, for example Al, Mg, Si, Sic, B4C, si3N4, A1N, BN or else SiAlON. Within the scope of the invention, use is made of the known technology for the production of such carbon- 20 containing bricks by producing bricks used according to the invention by means of the appropriate technology. The sealing zone according to the invention prevents, in particular in combination with a low porosity of the 25 unfired brick material, infiltration of volatile components from the furnace atmosphere, e.g. alkali metal compounds, chlorine compounds and sulfur compounds, which could damage or destroy the masonry. 30 Furthermore, a high measure of thermochemical resistance to attack by, for example, cement clinker phases is ensured by the sealing zone according to the invention and, in particular, also by a low porosity. 35 In addition, the graphite content effects, in - 6a - particular in combination with carbon-containing binders, a desirably low modulus of elasticity E and correspondingly a desirably low shear modulus G. - 7 - In the case of the raw material components MgO and carbon, the graphite-containing zones or the bricks are very thermally stable, Even a paxtial or complete- replacement of the HgO by other refractory materials 5 such as spinels, a-alumina, bauxite, andalusite, mullite, flint clay or chamotte does not impair the sealing action. The oxidizing atmosphere surprisingly produces only a 10 minimal burning out of carbon on the hot side of the masonry, with the resulting ashing likewise surprisingly leading to a type of sealing zone on the surface of the brick, probably due to sintering processes at the brick surface, without other materials 15 properties of the bricks being lost, In the sintering zone and possibly also in the transition zones, the desired deposits are formed more quickly and are acre durable. Detached material is relatively rare even in the case of overheating and stress changes. 20 According to the invention, bricks which can withstand the attack of the hot cement clinker phases, e.g. bricks based on MgO and graphite, are used for the hot furnace zones such as the sintering and transition 25 zones, e.g. of rotary tube furnaces or shaft kilns. These advantageously comprise the abovementioned antioxidants which control the burning away of the carbon. In addition, the antioxidants increase the strength of the brick on the use side. The bricks can 30 comprise not only magnesia (sintered magnesia or fused magnesia) but also spinel, bauxite or a-alumina, or magnesia can be replaced completely by these minerals, especially where the thermal conductivity is to be reduced. 35 The bricks of the invention are used not only for the hot zones of rotary tube furnaces and shaft kilns, but advantageously also for all other zones. For example, the safety zone is provided with carbon-containing - 7a - bricks which comprise, as alumina-containing constituent, andalusite or another mineral of the sillimanite group, bauxite or an alumina-rich special chambtta- The carbon content of the bricks should - 8 - in this case, too, be in the range from 2 to 30% by weight. These bricks, too, can further comprise antioxidants for the indicated purpose. 5 The invention also provides for use of carbon- containing chamotte bricks which are preferably likewise resin-, tar- or pitch-bonded like the other bricks for the preheating zone of the furnaces which have hitherto usually been, lined with chamotte bricks. 10 However, these carbon-containing bricks can also be bonded by means of other organic or inorganic materials and can further comprise antioxidants for the abovementioned purpose. 15 The furnace outlet, which has hitherto been lined with fired bauxite bricks, is, according to the invention, preferably lined with carbon-containing alumina-rich bricks, for example bauxite bricks or with carbon- containing magnesia bricks, which comprise 20 antioxidants, in particular to ensure a higher strength because of the abrasive stresses occurring in the furnace outlet. Should the temperatures on the outside of the firing 25 apparatus, vis. the outer wall of the furnace, become too high during use, it is possible to line the furnace with a two-layer masonry lining. This masonry comprises the carbon-containing bricks described, which comprise refractory minerals, graphite and, if appropriate, 30 antioxidants, on the hot side and insulating masonry comprising, for example, a commercial chamotte brick or another thermally insulating material, for example a lightweight chamotte brick, on the side facing the outer wall of the furnace. 35 Bricks according to the invention comprise graphite in the hot zone. The cold side of the brick can comprise, for example, the same material without graphite or a thermally insulating material. Fig. 1 shows such a - 8a - structure, with the two-layer brick 1 consisting of the graphite-containing zone 2 on the hot side and the insulating zone 3 on the cold side. These bricks can be produced in one process and have a durable bond between - 9 - the two zones. Of course, it is also possible for the insulating part and the carbon-containing part to be manufactured separately and be adhesively bonded together by means of an adhesive to aid installation, 5 Fig. 2 schematically shows an example of the lining of a rotary tube furnace for cement. Here, the preheating zone is lined with carbon-containing chamotte bricks, the safety zone is lined with carbon-containing 10 alumina-rich bricks and/or carbon-containing bauxite- bricks, the upper transition zone is lined with carbon- containing magnesia bricks and/or carbon-containing magnesia spinel bricks, the sintering zone is lined with carbon-containing magnesia bricks and/or carbon- 15 containing magnesia spinel bricks and the lower transition zone is lined with carbon-containing magnesia bricks and/or carbon-containing magnesia spinel bricks. Fig. 2 shows the rotary tube 4, the firing flame 5 and the burner 6. 20 The invention is illustrated below with the aid of the following examples of a refractory masonry lining. Example I: Rotary tube furnace 25 A rotary tube furnace for cement in which a portland cement clinker is fired under typical operating conditions is used as a starting point. The length of the furnace is 75 m, and the diameter is 4,50 m. The 30 division into zones as shown in fig. 2 is as follows: Outlet zone FP 0 - 5 m lower transition zone FP 5 - 12 m Sintering sorts FP 12 - 30 m 35 Upper transition zone FP 30 - 43 m Safety zone FP 43 - S2 m Preheating zone FP 52 - 75 m FP = point in the rum&ce (in cumulative meters) - 9a - A lining according to the invention is provided as follows: -10 – Outlet zone FP 0-5 m Lining is effected by means of a magnesia brick having a graphite content of 10% by weight; the composition of 5 this brick is as follows: Sintered magnesia grain 0-4 mm 71% by weight Sintered magnesia flour Floc graphite 10% by weight 10 Aluminum powder 3% by weight Silicon power 3% by weight The binder is a phenolic resol which is addsd in an amount of 3.2% by weight to the dry mix. The brick is 15 pressed in the customary formats for the cement industry (known as VD2 formats) at a pressing pressure of 160 MPa and subsequently heated at a temperature of 200oC. 20 The installation of the bricKs is carried out using the installation tools and methods customary in the cement industry. Lower transition zone FP 5-12m 25 Lining is effected by means of a magnesia brick having a graphite content of 10% by weight; the composition of this brick is as follows: 30 Fused magnesia grain 0-4 mm 71% by weight Fused magnesia flour Floe graphite 10% by weight Aluminum powder 3% by weight Silicon powder 3% by weight 35 The binder is a phenolic resol which is added in an amount of 3.1% by weight. The brick is pressed in the customary formats for the cement industry (known as VDZ formats) at a pressing pressure of 160 MPa and - 10a - subsequently heated at a temperature of 200°C. in this case, fused magnesia is used since the stresses are usually highest - 11 - in the lower transition zone. In the case of relatively low stresses, the use of sintered magnesia is also possible. 5 Here too, the installation of the bricks is carried out using, the installation tools and methods customary in the cement industry. Sintering zone FP 12-3.0 m . 10 Lining is effected by means of a magnesia brick having a graphite content of 10% by weight; the composition of this brick is as follows: 15 Sintered magnesia grain 0-4 mm 48% by weight Sintered magnesia flour Sintered spinel 0-4 mm 20% by weight Floe graphite 10% by weight Aluminum powder 3% by weight 20 Silicon powder 3% by weight Silicon carbide powder 3% by weight The binder is a phenolic resol which is added in an amount of 3.1% by weight. The brick is pressed in the 25 customary formats for the cement industry (known as VDZ formats) at a pressing pressure of 160 MPa and subsequently heated at a temperature of 200OC. In this case, sintered spinel is additionally used in order to aid deposit formation and at the same time reduce the 30 thermal conductivity of the lining. Of course, the use of fused magnesia and fused spinel is also possible. Aluminum powder, silicon, powder and silicon carbide powder serve as antioxidants to control sealing and strengthen the microstructure, 35 Here too, the installation of the bricks is carried out using the installation tools and methods customary in the cement industry. -12 – Upper transition zone FP 30-43 in Lining is effected in this example by means of a magnesia brick having a graphite content of 10% by 5 weight; the composition of this brick is as follows: Sintered magnesia grain 0-4 mm 48% by weight Sintered magnesia flour Fused: ot-alumina 0-4 mm 20% by weight 10 Floc graphite 10% by weight Aluminum powder 3% by weight Silicon powder 3% by weight Silicon carbide powder 3% by weight 15 The binder is a phenolic resol which is added in an amount of 3,2% by weight. The brick is pressed in VDZ formats at a pressing pressure of 160 MPa and subsequently heated at a temperature of 2O0°C. In this case, fused a-alumina is additionally used in order to 20 reduce the thermal conductivity of the lining. Of course, the use of sintered a-alumina is also possible. Aluminum powder, silicon powder and silicon carbide powder serve as antioxidants to regulate sealing and to strengthen the microstructure. 25 The installation of the bricks is carried out in a manner analogous to the other bricks. Safety zone FP 43-52 m 30 Lining is effected in this example by means of an alumina-rich brick having a graphite content of 10% by weight; the composition of this brick is as follows: 35 Flint clay 0-4 mm 6B% by weight Ground flint clay Floc graphite 10% by weight Aluminum powder 3% by weight Silicon powder 3% by weight -12a – Silicon carbide powder 3% by weight The binder is a phenolic resol which is added in an amount of 3.4% by weight. The brick is pressed in A 5 formats (ISO formats) - 13 - at a pressing pressure of 160 MPa and subsequently heated at a temperature of 200oC. Aluminum powder, silicon powder and silicon carbide powder serve as antibxidants to regulate sealing and to strengthen the 5 microstructure, in addition, silicon carbide increases the resistance to alkali attack. The installation of the bricks is carried out in a manner analogous to the other bricks. 10 Preheating zone FP 52-75 m Lining is effected in this example by means of a lightweight chamotte brick having a graphite quantity 15 of 10% by weight; the composition of this brick is as follows: Lightweight chamotte 0-4 mm 63% by weight Lightweight chamotte flour 20 Floc graphite 10% by weight Aluminum powder 34% by weight Silicon powder 3% by weight Silicon carbide powder 3% by weight 25 The binder is a phenolic resol which is added in an amount of about 3.8% by weight. The brick is pressed, in A formats (ISO formats) at a pressing pressure of 120 MPa and subsequently heated at a temperature of 200CC. Aluminum powder, silicon powder and silicon 30 carbide powder serve as arttioxidants to regulate sealing and to strengthen the microstructure. In addition, silicon carbide powder increases the resistance to alkali attack. The pressing pressure selected is lower in this case, since high compaction 35 is not necessary for bricks in this region. In particular cases, for example when the brick is subjected to a high concentration of alkalis from the furnace atmosphere, it is of course also possible to use a more highly compacted brick for this purpose - 13a - i without problems. The installation of the bricks is carried out in a manner analogous to the bricks described above. - 14 - Example 2: Shaft kiln A shaft kiln for line as is shown in cross section in fig. 3 and in which lime stone is fired to produce CaO 5 under typical operating conditions is used as a starting point. The height of the klin is 23 m, the Internal diameter is 4.00 and the external diameter is 5.20 m. The division, into zones as shown in fig. 4 is as follows (points of the furnace are counted front 10 the bottom) : Inlet (preheating) zone FP 19.6 - 23 m Sintering zone FP 1,4 - 19.6 m Outlet (cooling) zone FP 0 - 1.4 m 15 In general, a calcium silicate tile lining (thickness: 2 5 mm) is provided directly on the wall of the kiln to insulate the shaft kiln thermally, followed by a refractory brick lining (thickness: 64 mm) in the direction, of the interior of the kiln, followed 20 subsequently by a lining with a lightweight refractory brick (thickness; 124mm, typical density: 1.50 - 1.65 g/cm3) , then followed by a lining with a typical chamotte brick (thickness: 124 mm, typical density: 2.0 - 2.30 g/cn3) , and in the interior the 25 working lining of graphite-containing bricks employed according to the invention. To compensate expansion differences, a layes of Styropor is provided between the graphite-containing bricks and the chamotte bricks. 30 Inlet (preheating) zone FP 19.6 - 23 m Lining is effected in this example by means of a chamotte brick having a graphite content of 10%; the composition of this brick is thus as follows: 35 Chamotte 0-4 mm 63% by weight Chainotte flour Floe graphite 10% by weight - 14a - Aluminum powder 3% by weight Silicon powder 3% by weight Silicon carbide powder 3% by weight 5 The binder is a phenolic resol which is added in an amount of about 3.5% by weight. The brick is pressed in A formats - 15 - (ISO formats) at a pressing pressure of 120 MPa and subsequently heated at a temperature of 200°C. Aluminum power, silicon powder and silicon carbide powder serve as antioxidants and to strengthen the microstructure. 5 In addition, silicon carbide powder increases the resistance to alkali attack. The pressing pressure selected is lower in this case, since high compaction is not necessary for bricks in this region. In particular cases, for example when the brick is 10 subjected to a high concentration of alkalis from the furnace atmosphere, it is of course also possible to use a more highly compacted brick: for this purpose without problems - 15 The installation of the briclts is carried out using the installation tools and methods customary in the lime industry. Sintering zone FP 1.4 - 13,6 m 20 Lining is effected in this example by means of a magnesia brick 1 having a graphite content, of 10%; the composition of this brick is thus as follows: 25 Sinter magnesia grain 0-4 mm 71% by weight Sintered magnesia flour Floc graphite 10% by weight Aluminum powder 3% by weight Silicon powder 3% by weight 30 In the case of increased stresses, for example due to abrasive stress, it is also possible to use fused magnesia in place of sintered magnesia. The binder is a phenolic xesol which is added in an amount of 3.2% by 35 weight. The brick is pressed in A formats (ISO formats) at a pressing pressure of 160 MPa and subsequently heated at a temperature of 200°C. The installation of the bricks is carried out using the - 15a - installation tools and methods customary in the line industry. -16 – Outlet (cooling) zone FP 0 - 1.4 m Lining is likewise effected in this example by means of a chamotte brick (as in the inlet (preheating) zone) 5 having a graphite content of 10% by weight; the composition of this brick is thus as follows: Chamotte 0 - 4 mm 68% by weight Chamotte flour 10 Floe graphite 10% by weight Aluminum powder 3% by weight Silicon powder 3% by weight Silicon carbide powder 3% by weight 15 The binder is a phenolic resol which is added in an amount of about 3,5% by weight. The brick is pressed in A formats (ISO formats) at a pressing pressure of 120 MPa and subsequently heated at a temperature of 200°C. Aluminum powder, silicon powder and silicon 20 carbide powder serve as antioxidants. and to strengthen the microstructure. In addition, silicon carbide powder increases the resistance to alkali attack. The pressing pressure selected is lower in this case, since high compaction is not necessary for bricks in this region. 25 In individual cases, for instance in the case of high abrasive stress, it is of course also possible to use a more highly compacted brick Without problems. The installation of the bricks is carried out using the 30 installation tools and methods customary in the lime industry. Preference is given to refractory bricks having the following compositions; 35 Magnesia 25 - 98% by weight, in particular 27 - B3% by weight - 16a - Spinel mineral or 0 - 40% by weight, in particular a-alumina 5 - 30% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2-8% by weight Silicon powder 0 - 10% by weight, in particular 2 - B% by weight Silicon carbide 0 - 10? by weight, in particular Powder 3 - 7% by weight - 17 - Alumina-rich 50 - 98% by weight, in particular Chamotte 57 - 83% by weight Graphite 2 — 30% by weight, in particular 5 - 20$ by weight Aluminum powder 0 - 10% by weight, in particular 2 - 6% by weight Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3-7% by weight Lightweight 50 - 98% by weight, in particular Chamotte 57 - 88% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 9% by weight Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight -17a- Refratechnik Holding GmbH Nomember 15, 2003 PCT/EPO3/02248 M 6131 PCT/l/al Main. claim 1. A Large-volume industry furnace in which mineral, 5 products, e.g. cement, lime, magnesite, dolomite or the like, are fired in an essentially oxidizing furnace atmosphere at temperatures above 700oC, wherein the industry furnace comprises masonry composed of unfired bricks of refractory material and the bricks in the 10 interior in the fire-side or hot-side surface region of the masonry contain from 2 to 30% by weight of carbon, with the carbon being present in the form of graphite and in the form of carbon-containing binder and carbon- containing binder being present in amounts of from 2 to 15 5% by weight. AMENDED SHEET - 18 - Refratechnik Holding GmbH April l, 2004 M 6137 PCT/I/dl Claims 2. An industrial furnace as claimed in claim 1, 5 characterized by bricks composed of refractory material customarily used for such furnaces, which in the region of the surface on the fire-side of the masonry have carbon present in a zone, in particular in a zone having a thickness of from 1 to 18 cm, preferably from 10 2 to 15 cm. 3, An industrial furnace as claimed in claim 1 3and/or 2, characterised in that the bricKs have the formats customarily used. 15 4. An industrial furnace as claimed in one or more of claims 1 to 3, characterized in that the carbon is present in the bricks in the form of natural or synthetic graphite. 20 5. An industrial furnace as claimed in claim 4, characterized in that AMENDED SHEET - 19 - the bricks comprise floc graphite. 6 An industrial furnace as claimed in claim 4 and/or 5, characterized in that the binder is tar and/or 5 pitch. 7. An industrial furnace as claimed in claim 4 and/or 5, characterized in that the bricks comprise synthetic resin as binder, 10 8, An industrial furnace as claimed in claim 7, characterised in that the bricks comprise phenolic resin as binder. 15 9. An industrial furnace as claimed in claim 7, characterized in that the bricks comprise phenolic resin-novolak as binder. 10. An industrial furnace as claimed in one or more of 20 claims 1 to 9, characterized in that from 5 to 20% by weight of graphite is present in the carbon-containing zone of the bricks. 11. An industrial furnace as claimed in one or more of 25 claims 1 to 10, characterised in that the carbon- containing binder is present in the bricks in amounts or from 2.5 to 4% by weight. 12. An industiral furnace as claimed in claim 1 or in 30 one or more of claims 1 to 11, characterized in that the carbon is homogeneously distributed in the entire brick. AMENDED PAGE - 20 - 13. An industrial furnace as claimed in claim 12, characterised in that the masonry is constructed of bricks comprising, in particular, a basic refractory material, in particular on the basis of Mgo. 5 14. An industrial furnace as claimed in claim 13, characterized in that the masonry is constructed of bricks in which MgO is at least partly replaced by spinel and/or a-alumina and/or bauxite and/ox 10 andalusite and/or mullite and/or flint clay and/or chamotte. 15. An industrial furnace as claimed in one Or more of claims 1 to 14, characterized in that the bricks have a 15 porosity of less than. 30% by volume, in particular Less than 14% by volume, preferably a porosity in the range from 1 to 8% by vo]_volume. 16. An industrial furnace as claimed in one or more of 20 claims 1 to 15, characterized in that the bricks comprise antioxidants known per se, in particular in amounts of from 1 to 10% by weight, preferably in amounts of from 2 to 8% by weight. 25 17. An industrial furnace as claimed in one or more of claims 1 to 16 in a sintering zone and/or upper transition zone of a rotary tube furnace or shaft kiln, characterized by carbon-containing bricks based on MgO and/or MgO/spinel mineral or MgO/bauxite or MgO/a- 30 alumina or MgO/zircronimn oxide. 18. An industrial furnace as claimed in claim 17, characterized in that AMENDED PAGE -21 – the bricks have the following composition: Magnesia 25 - 98% by weight, in particular 27 - 83% by weight Spinel mineral 0 - 4 0% by weight, in particular 5 - 30% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0-10% by weight/ in particular 2-8% by weight Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular powder 3-7% by weight Binder 2 - 5% by weight, in particular 2,5-4% by weight 19, An industrial furnace as claimed in claim 17, 5 characterized by carbon-containing bricks based on spinel or bauxite or a-alumina- 20. An industrial furnace as claimed in one or more of claims 1 to 19 in a safety zone of a rotary tube 10 furnace or shaft kiln, characterized by carbon- containing bricks based on andalusite or a mineral of the sillimanite group or bauxite or alumina-rich chamotte such as flint clay, 15 21. An industrial furnace as claimed in claim 20, characterized by bricks of the following composition: Alumina-rich 50 - 98% by weight, in particular Chamotte 57 - 9 3% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 8% by weight AMENDED PAGE - 21a - Silican powder 0 - 10% ^ -weight, in particular 2 - 6% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight Binder 2 - 5% by weight, in particular 2.5 - 4% by weight 22. An industrial furnace as claimed in one or more of claims 1 to 21 in a preheating zone of a rotary tube 5 furnace or shaft kiln, characterised by carbon- containing bricks based on chamotte or lightweight charnotte. AMENDED PAGE - 22 - 23. An industrial furnace as claimed in claim 22, characterized by bricks of the following composition: Lightweight 50 - 98% by weight, in particular Chamotte 57 - 88% by weight Graphite 2 - 301 by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight Binder 2-5% by veight, in particular 2-5 - 4% by weight 5 24, An industrial furnace as claimed in one or more of claims 1 to 23 in a lower transition zone or in an outlet zone of a rotary tube furnace or shaft kiln, characterised by carbon-containing bricks based on 10 bauxite or magnesia. 25. An industrial furnace as claimed in one or more of claims 1 to 24, characterised by multilayer masonry in which the carbon-containing bricks are located on the 15 hot side and bricks comprising an insulating material, e.g. lightweight refractory bricks or chamotte bricks, are located on the cold side. 26. A refractory brick for producing the masonry in an 20 industrial furnace as claimed in one or: more of claims 1 to 25, characterized by a one-piece structure coinprising a carbon-containing hot-side zone 2 having a brick composition as cLaimed in one or more of claims 1 to 24 and a thermally insulating zone 3 comprising a 25 thermally insulating material. 27, A refractory brick for producing masonry as AMENDED PAGE - 22a - claimed in one or more of claims 17 to 19, characterized by the following composition: AMENDED PAGE - 23 - Magnesia 25 - 98% by weight, in particular 27 - 83% by weight Spinel mineral or 0 - 40% by weight, in particular a-alumina 5 - 30% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2-8% by weight Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight Binder 2-5% by weight, in particular 2.5 - 4% by weight 28. A refractory brick for producing masonry as claimed in claim 20, characterized by the following 5 composition: Alumina-rich 50 - 98% by weight, in particular Chamotte 57 - 88% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon powder 0 - 1D% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3-7% by weight Binder 2-5% by weight, in particular 2.5 - 4% by weight 29. A refractory brick for producing masonry as claimed in claim 22, characterized by the following 10 composition: AMENDED PAGE - 23a - Lightweight 50 - 98% by weight, in particular chaste 57 88% by weight Graphite 2 -30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 -100% by weight silicon powder 0 - 10% by weight, in particular 2 - 10% by weight Sxlicon carbide 0- 10% by weight, in particular powder 3 - 7% by weight Binder 2 - 5% by weight, in particular 2.5 - 4% by weight AMENDED PAGE -24- Refratechnik Holding GmbH March 5, 2003 Adalperostr. 82 M 613.7 PCT/I/ho 85737 Ismaning Abstract Refractory masonry in a large-volume industry furnace in which mineral products, e.g, cement, Lime, magnesite, dolomite or the like, are fired in an essentially oxidizing furnace atmosphere at temperatures above 700"C, wherein the masonry is composed of unfired bricks of refracted material and carbon is present in the fire-side or hot-side surface region of the bricks of the masonry. In addition, the invention relates to refractory bricks for producing the masonry. - 18 - Refratechnik Holding GmbH March 5, 2003 Adalperostr. 82 M 6137 PCT/l/ho 85737 Ismaning Claims 5 1. A refractory masonry in a lstge-volume industry furnace in which mineral products, e.g. cement, lime, matgnesite, dolomite or the like, are fired in an essentially oxidizing furnace atmosphere at temperatures above 700ºc, characterized in that the 10 masonry is composed of unfired bricks of refractory material and carton is present in the fire-side or hot- side surface region of the bricks of the masonry. 2. The masonry as claimed in claim 1, characterized 15 by bricks composed of refractory material customarily used for such furnaces, which in the region of the surface on the fire-side of the masonry have carbon present in a zone, in particular in a zone having a thickness of from 1 to 13 cm, preferably from 2 to 20 15 cm. 3. The masonry as claimed in claim 1 and/or 2, characterized in that the bricks have the formats customarily used. 25 4. The masonry as claimed in one or more of claims 1 to 3, characterised in that the carbon is present in the bricks in the form of graphite. 30 5. The masonry as claimed in claim 4, characterized in that the bricks comprise floc graphite. AS ORlGINAlLY FILED - 19 - 6. The masonry as claimed in claim 4 and/or 5, characterized in that the bricks further comprise carbon in the form of carbon-containing binder, e.g. tar and/or pitch. 5 7. The masonry as claimed in claim 6, characterized in that the bricks comprise synthetic resin as binder, 8. The masonry as claimed in claim 7, characterized 10 it that the bricks comprise phenolic resin as binder, 9. The masonry as claimed in claim 7, characterized in that the bricks comprise phenolic resin-novolak as binder, 15 10. The masonry as claimed in one or more of claims 4 to 9, characterized in that from 2 to 30% by weight, in particular from 5 to 20% by weight, of carbon is present in the carbon-containing zone or the bricks. 20 11. The masonry as claimed in one or more of claims 4 to 9, characterized in that the bricks contain from 2 to 5% by weight, in particular from 2.5 to 4% by weight , of a carbon -containing binder. 25 12 The masnry as claimed in claim 1 or in one or more of claims 3 to 11, characterized in that the carbon is homogeneously distributed in the entice brick. AS ORIGINALLY FIELD - 20 - 13. The masonry as claimed in claim 12, characterized in that it is constructed of bricks comprising, in particular, a basic refractory material, in particular on the basis of MgO. 5 14. The masonry as claimed in claim 13, characterized in that it is constructed of bricks in which MgO is at least partly replaced by spinel and/or a-alumina and/or bauxite and/or andalusite and/or mullite and/or flint 10 clay and/or chamotte. 15. The masonry as claimed in one or more of claims 1 to 14, characterized in that the, bricks have a porosity of less than 30% by volume, in particular less than 14% 15 by volume, preferably a porosity in the range from 1 to 8% by volume. 16. The masonry as claimed in one or more of claims 1 to 15, characterized in that the bricks comprise 20 antioxidants known per se, in particular in amounts of from 1 to 10% by weight, preferably in amounts of from 2 to 8% by weight. 17. The masonry as claimed in one or more of claims 1 25 to 16 in a sinering zone and/or Tapper transition zone of a rotary tube furnace or shaft kiln, characterised by carbon-containing bricks based on MgO and/or MgO/spinel mineral or MgO/bauxite or MgO/a-alurnirta or MgO/zirconium oxide. 30 18. The masonry as claimed in claim 17, characterized in that the bricks have the following composition: Magnesia 25 - 98% by weight, in particular 27 - 83% by weight Spinel mineral 0 - -40% by weight, in particular 5 - 30% by weight AS ORIGINALLY FILED - 21 - Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2-8% by weight Silicon powder 0 - 10% by weight, in particular 2-8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight 19. The masonry as claimed in claim 17, characterized by carbon-containing bricks based on spinel or bauxite 5 or a-alumina. 20. The masonry as claimed in one or more of claims 1 to 19 in a safety zone of a rotary tube furnace or shaft kiln, characterized by carbon-containing bricks 10 based on andalusits or a mineral of the sillimatite group or bauxite or alumina-rich chamotte such as flint clay. 21. The masonry as claimed in claim 20, characterized 15 by bricks of the following composition: Alumina-rich 50 - 98% by weight, in particular Chamotte 57 - 88% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon powder 0 - 10%'by weight, in particular 2 - 8% by -weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 1% by weight 22. The masonry as claimed in one or more of claims 1 to 21 in a preheating zone of a rotary tube furnace or 20 shaft kiln, characterised by carbon-containing bricks AS ORIGINALLY FILED -21a – based on chamotte or lightweight chamotte. 23. The masonry as claimed in claim 22, characterized by bricks of the following composition: 5 Lightweight 50 - 98% by weight, in particular chamotte 51 - 88% by weight Grapbite 2 - 30% by weighty in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 8% by weight AS ORIGINALLY FILED - 22 - Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3-7% by weight 24. The masonry as claimed in one or more of claims 1 to 23 in a lower transition zone or in an outlet zone 5 of a rotary tube furnace or shaft kiln, characterized by carbon-containing bricks based on bauxite or magnesia. 25. The masonry as claimed in one or more of claims 1 10 to 24, characterized by multilayer masonry in which the carbon-containing bricks are located on the hot side and bricks comprising an insulating material, e.g. lightweight refractory bricks or chamotte bricks, ace Located on the cold side. 15 26: A reitactory brick for producing masonry as claimed in one or more of claims 2 to 11 and 13 to 25, ctaracterized by a one-piece structure comprising a carbon-containing hot-side zone 2 and a thermally 20 insulating zone 3 comprising a thermally insulating material. 27. A refractory brick for producing masonry as claimed in one or more of claims 17 to 13, 25 characterised by the following composition: Magnesia 25 - 96% by weight, in particular 27 - 83% by weight Spinel mineral or 0 - 40% by weight, in particular a-alumina 5 - 30% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particulars 2-8% by weight AS ORIGINALLY FILED - 22a - Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight 28. A refractory bricK for producing masonty as claimed in claim 20, characterized by the following 5 composition: AS ORIGINALLY FLED - 23 - Alumina-rich 50 - 93% by weight;, in particular Chamotte 57 - 38% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 3% by weight Silicon powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular Powder 3 - 7% by weight 29. A refractory brick for producing masonry as claimed in claim 22, characterised by the following 5 composition: Lightweight 50 - 98% by weight. in particular Chamotte 57 - 88% by weight Graphite 2 - 30% by weight, in particular 5 - 20% by weight Aluminum powder 0 - 10% by weight, in particular 2 - 8% by weight Silicon powder 0 - 104 by weight, in particular 2 - 8% by weight Silicon carbide 0 - 10% by weight, in particular powder. 3-7% by weight AS ORIGINALLY FLED in which mineral products, e.g, cement, Lime, magnesite, dolomite or the like, are fired in an essentially oxidizing furnace atmosphere at temperatures above 700"C, wherein the masonry is composed of unfired bricks of refracted material and carbon is present in the fire-side or hot-side surface region of the bricks of the masonry. In addition, the invention relates to refractory bricks for producing the masonry.

Full Text

Refractory wall and refractory bricks for building said wall

5 The invention relates to refractory masonry and
refractory bricks for producing the refractory lining
of large-volume industrial furnaces in which mineral
products such as cement, lime, magnesite, dolomite or
the like are fired under an essentially oxidizing
10 atmosphere at temperatures above 700oC, in particular
above 900°C.
In industry, cement, line, magnesite and dolomite are
mainly fired in rotary tube furnaces or shaft kilns.
15 The firing process is essentially carried out under
oxidizing conditions.
The operating life of the furnaces depends, inter alia,
on the type of refractory masonry lining which,
20 firstly, protects the metal outer wall of the furnace
from the high temperatures of the material being fired,
flame temperatures and atmospheric temperatures and,
secondly, reduces heat losses. In addition, the
refractory lining can act as a heat exchanger which
25 takes up the heat energy from the hot furnace gases and
passes it to the material being fired.
The masonry lining of the furnace is usually subjected
to high temperature-change stresses and high mechanical
30 and chemical stresses- The temperature-change stresses
result from the higher temperature of the furnace gases
compared to the temperature of the material being
fired. Mechanical stresses are caused by rotary motion
of the furnace and by movement of the material being
35 fired. The masonry is subjected to chemical stresses by

- 1a -
constituents of the material being fired and by
volatile compounds in the furnace atmosphere which
deposit in the refractory lining as a result of
temperature gradients.

— 2 —
These furnaces which are operated under oxidizing
conditions, e.g. rotary furnaces for cement and lime,
furnaces for dolomite and magnesite and shaft kilns,
are lined with fired refractory bricks, in the basic
5 region essentially with refractory bricks based .on Mgo,
e.g. with magnesia spinel bricks, magnesia chromite
bricks, magnesia hercynite bricks as magnesia spinel
mineral bricks, magnesia zirconia bricks, dolomite
bricks ox the like and in the nonbasic region with
10 chamotte bricks, andalusite bricks, bauxite bricks or
the like.
The lining is occasionally also constructed using
unfired phosphorus- or phosphate-bonded lightweight
15 refractory bricks in some zones.
For the purposes of constructing the masonry, the
furnaces are divided into various zones because
different stresses occur in the zones during operation.
20 In the case of a rotary tube furnace for cement, the
furnace is divided, going from the feed end for the
material being fired to the outlet end for the material
being fired, into, for example, a preheating zone, a
safety zone, an upper transition zone, a sintering
25 zone, a lower transition zone and an outlet zone. A
stable accumulation of material being fired is
generally formed in the sintering zone, and this can
protect the sintering zone. Detachment of material from
this accumulation can cause damage, as can cement
30 clinker phase infiltration in the event of overheating.
If the accumulation is absent or unstable, the
transition zones are subjected to alkali Infiltration,
thermal influences and redon influences and also
temperature changes. In addition, thermomechanical
35 stresses occur, for example, as a result of ovality
stresses and curvature of the furnace axis. Secondary
fuels, e.g. automobile tires, also produce additional
uncontrollable stresses.

- 2a -
The preheating, safety and outlet zones are generally
lined with bricks which are rich in chamotte and
alumina, while the other zones are generally lined with
bricks based on magnesia (MgO) or dolomite (MgO/OaO).
5
Shaft kilns are generally divided similarly.

- 3 -
When operating conditions are uniform, the known
furnace linings provide the prescribed properties and
protect against premature attrition. However, uniform
operating conditions can often not be achieved. Changes
5 in furnace operating parameters or materials
parameters, e.g. in respect of clinker moduli in the
firing of cement or necessary repair of previous damage
is not carried out in good time, frequently occur
within a relatively short time. Changing chemical
10 attacks and changing thermal and thermomechanical
stresses lead to accelerated attrition and to damage.
Attempts have been made in the past to counter this
problem by improving the materials composition of the
15 fired bricks and thus to match them to unfavorable
operating conditions. This application-oriented
optimization comprises essentially changing the
chemical-mineralogical composition of the bricks with
the aim of, for example, increasing their elastic
20 properties and corrosion resistance. An example is
provided by magnesia spinel bricks which generally
ensure a higher elasticity than magnesia chromite
bricks. In addition, the magnesia chromite bricks are
subject to higher corrosion due to attack by cement
25 clinker phases. This is countered by means of magnesia
zirconia bricks which are less stress-sensitive.
Accordingly, these bricks have been developed further
and special bricks designed for the respective stress
case have been produced. However, since the stress
30 cases are varied, this development leads to a dead end
and is very costly.
It is an object of the invention to provide refractory
masonry for furnaces operated using an oxidizing
35 furnace atmosphere, which survives stress changes
significantly better and whose refractory brick
material is optimally matched to the normal stresses
and not to the stress changes.

- 3a -
This object is achieved by the features of claim 1,
Advantageous embodiments of the invention are defined
in the subordinate claims.

- 4 -
According to the invention, unfired refractory bricks
composed of customarily used material, e.g. one of the
abovementioned refractory materials, which have
customarily used three-dimensional shapes and are
5 phosphorus-bonded or whose binder is a synthetic resin,
tar or pitch or are bonded by means of another suitable
material are employed.
It is important that carbon, particular graphite, is
10 present in the brick material, in particular in the
pores, on the side of the masons or the bricks facing
the interior of the furnace. The graphite can be a
natural or synthetic graphite, e.g. floe graphite. It
has been found that the graphite together with the
15 material being fired and/or the oxidizing atmosphere in
all zones obviously produces a type of sealing of the
surface of the unfired bricks which not only does not
disturb the desired optimised properties in respect of
the different stresses in the zones but also ensures
20 the prescribed properties in the case of stress
changes. The graphite is particularly effective in
combination with a carbon-containing binder material
such as synthetic resin, tar or pitch, with the action
being particularly good when synthetic resin is
25 present. Synthetic resins are used, in particular
phenolic resins (phenol resol) or phenolic resin-
novalak solutions.
It is advantageous to provide a graphite-containing
30 zone of from about 1 to 18 cm, preferably from 2 to
15 cm, which makes the graphite available for the
oxidizing surface reaction with the material being
fired and/or the furnace atmosphere, and may
additionally provide a reserve stock of graphite and,
35 if appropriate, carbon-containing binders in the
interior of the brick. The sealing zone obviously
protects the furnace-side (hot-side) surface region of
the bricks so that not all of the graphite from the
graphite-containing zone is consumed and is available

- 4a -
for further sealing in the event of damage to the
surface.

- 5 -
The porosity in the graphite-containing zone, but
preferably also in the entire unfired brick, is
advantageously less than 30% by volume, preferably less
than 14% by volume, in particular, the porosity is in
5 the range from 1 to 8% by volume.
The graphite content of the graphite-containing zone is
preferably from 2 to 30% by weight, in particular from
S to 20* by weight. In the case of carbon-containing
10 binders, the carbon content of binder plus grapftite
should be within the indicated limits of from 2 to 30%
by weight, in particular from 5 to 20% by weight. The
carbon-containing binder is preferably used in amounts
of from 2 to 5% by weight, in particular from 2-5 to 4%
15 by weight.
In a particular embodiment of the invention, the
graphite-containing zone . further comprises
antioxidants, for example AL, si, mg, sic, Si3N4, B4C or
20 metallic alloys. The antioxidants surprisingly do not
adversely affect the formation of the soaling zone on
the surface, but prevent excessively deep penetration
of the oxidation into the graphite-containing zone, so
that carbon, reserves remain for future reformation of
25 damage to sealing regions.
The use of bricks which are completely graphite-
containing or graphite-containing in their entirety or
throughout is encompassed by the scope of the
30 invention. It is likewise within the scope of the
invention, in particular, to use bricks which are
completely graphite-containing and are bonded by
carbon-containing binders such as synthetic resin, tar
or pitch. In this respect, the invention provides for
35 the use of basic, carbon-containing refractory bricks
known per se which have been designed for use in a
reducing a-atmosphere, e.g. for use in steel production,
for the masonry of furnaces operated under oxidizing
conditions. Such basic refractory bricks are used, for

- 5a -
example, for lining metallurgical vessels such as
converters, steel pouring ladles or electric are-
furnaces. These likewise unfired carbon-containing
bricks, in particular magnesia bricks or dolomite

- 6 -
bricks, ensure compatibility with most basic slags and
the stability of the carbon, in particular the graphite
too, in the reducing atmosphere which prevails in steel
production. The bricks are bonded by means of synthetic
5 resin, pitch or tar and are shaped in the cold state
(phenolic resin-bonded or phenolic resin-novalak-bonded
bricks) or in the hot state (phenolic resin-novalak It-
bonded or tar- or pitch-bonded bricks) . In addition,
the bricks generally further comprise antioxidants
10 which, owing to their higher affinity for oxygen
compared to carbon, reduce burning away of the carbon.
The action of the antioxidants is based mainly on their
making entry of gas more difficult and on an increase
in the strength- Materials typically used are metals,
15 carbides or nitrides, for example Al, Mg, Si, Sic, B4C,
si3N4, A1N, BN or else SiAlON.
Within the scope of the invention, use is made of the
known technology for the production of such carbon-
20 containing bricks by producing bricks used according to
the invention by means of the appropriate technology.
The sealing zone according to the invention prevents,
in particular in combination with a low porosity of the
25 unfired brick material, infiltration of volatile
components from the furnace atmosphere, e.g. alkali
metal compounds, chlorine compounds and sulfur
compounds, which could damage or destroy the masonry.
30 Furthermore, a high measure of thermochemical
resistance to attack by, for example, cement clinker
phases is ensured by the sealing zone according to the
invention and, in particular, also by a low porosity.
35 In addition, the graphite content effects, in

- 6a -
particular in combination with carbon-containing
binders, a desirably low modulus of elasticity E and
correspondingly a desirably low shear modulus G.

- 7 -
In the case of the raw material components MgO and
carbon, the graphite-containing zones or the bricks are
very thermally stable, Even a paxtial or complete-
replacement of the HgO by other refractory materials
5 such as spinels, a-alumina, bauxite, andalusite,
mullite, flint clay or chamotte does not impair the
sealing action.
The oxidizing atmosphere surprisingly produces only a
10 minimal burning out of carbon on the hot side of the
masonry, with the resulting ashing likewise
surprisingly leading to a type of sealing zone on the
surface of the brick, probably due to sintering
processes at the brick surface, without other materials
15 properties of the bricks being lost, In the sintering
zone and possibly also in the transition zones, the
desired deposits are formed more quickly and are acre
durable. Detached material is relatively rare even in
the case of overheating and stress changes.
20
According to the invention, bricks which can withstand
the attack of the hot cement clinker phases, e.g.
bricks based on MgO and graphite, are used for the hot
furnace zones such as the sintering and transition
25 zones, e.g. of rotary tube furnaces or shaft kilns.
These advantageously comprise the abovementioned
antioxidants which control the burning away of the
carbon. In addition, the antioxidants increase the
strength of the brick on the use side. The bricks can
30 comprise not only magnesia (sintered magnesia or fused
magnesia) but also spinel, bauxite or a-alumina, or
magnesia can be replaced completely by these minerals,
especially where the thermal conductivity is to be
reduced.
35
The bricks of the invention are used not only for the
hot zones of rotary tube furnaces and shaft kilns, but
advantageously also for all other zones. For example,
the safety zone is provided with carbon-containing

- 7a -
bricks which comprise, as alumina-containing
constituent, andalusite or another mineral of the
sillimanite group, bauxite or an alumina-rich special
chambtta- The carbon content of the bricks should

- 8 -
in this case, too, be in the range from 2 to 30% by
weight. These bricks, too, can further comprise
antioxidants for the indicated purpose.
5 The invention also provides for use of carbon-
containing chamotte bricks which are preferably
likewise resin-, tar- or pitch-bonded like the other
bricks for the preheating zone of the furnaces which
have hitherto usually been, lined with chamotte bricks.
10 However, these carbon-containing bricks can also be
bonded by means of other organic or inorganic materials
and can further comprise antioxidants for the
abovementioned purpose.
15 The furnace outlet, which has hitherto been lined with
fired bauxite bricks, is, according to the invention,
preferably lined with carbon-containing alumina-rich
bricks, for example bauxite bricks or with carbon-
containing magnesia bricks, which comprise
20 antioxidants, in particular to ensure a higher strength
because of the abrasive stresses occurring in the
furnace outlet.
Should the temperatures on the outside of the firing
25 apparatus, vis. the outer wall of the furnace, become
too high during use, it is possible to line the furnace
with a two-layer masonry lining. This masonry comprises
the carbon-containing bricks described, which comprise
refractory minerals, graphite and, if appropriate,
30 antioxidants, on the hot side and insulating masonry
comprising, for example, a commercial chamotte brick or
another thermally insulating material, for example a
lightweight chamotte brick, on the side facing the
outer wall of the furnace.
35
Bricks according to the invention comprise graphite in
the hot zone. The cold side of the brick can comprise,
for example, the same material without graphite or a
thermally insulating material. Fig. 1 shows such a

- 8a -
structure, with the two-layer brick 1 consisting of the
graphite-containing zone 2 on the hot side and the
insulating zone 3 on the cold side. These bricks can be
produced in one process and have a durable bond between

- 9 -
the two zones. Of course, it is also possible for the
insulating part and the carbon-containing part to be
manufactured separately and be adhesively bonded
together by means of an adhesive to aid installation,
5
Fig. 2 schematically shows an example of the lining of
a rotary tube furnace for cement. Here, the preheating
zone is lined with carbon-containing chamotte bricks,
the safety zone is lined with carbon-containing
10 alumina-rich bricks and/or carbon-containing bauxite-
bricks, the upper transition zone is lined with carbon-
containing magnesia bricks and/or carbon-containing
magnesia spinel bricks, the sintering zone is lined
with carbon-containing magnesia bricks and/or carbon-
15 containing magnesia spinel bricks and the lower
transition zone is lined with carbon-containing
magnesia bricks and/or carbon-containing magnesia
spinel bricks. Fig. 2 shows the rotary tube 4, the
firing flame 5 and the burner 6.
20
The invention is illustrated below with the aid of the
following examples of a refractory masonry lining.
Example I: Rotary tube furnace
25
A rotary tube furnace for cement in which a portland
cement clinker is fired under typical operating
conditions is used as a starting point. The length of
the furnace is 75 m, and the diameter is 4,50 m. The
30 division into zones as shown in fig. 2 is as follows:
Outlet zone FP 0 - 5 m
lower transition zone FP 5 - 12 m
Sintering sorts FP 12 - 30 m
35 Upper transition zone FP 30 - 43 m
Safety zone FP 43 - S2 m
Preheating zone FP 52 - 75 m
FP = point in the rum&ce (in
cumulative meters)

- 9a -
A lining according to the invention is provided as
follows:

-10 –
Outlet zone FP 0-5 m
Lining is effected by means of a magnesia brick having
a graphite content of 10% by weight; the composition of
5 this brick is as follows:
Sintered magnesia grain 0-4 mm 71% by weight
Sintered magnesia flour Floc graphite 10% by weight
10 Aluminum powder 3% by weight
Silicon power 3% by weight
The binder is a phenolic resol which is addsd in an
amount of 3.2% by weight to the dry mix. The brick is
15 pressed in the customary formats for the cement
industry (known as VD2 formats) at a pressing pressure
of 160 MPa and subsequently heated at a temperature of
200oC.
20 The installation of the bricKs is carried out using the
installation tools and methods customary in the cement
industry.
Lower transition zone FP 5-12m
25
Lining is effected by means of a magnesia brick having
a graphite content of 10% by weight; the composition of
this brick is as follows:
30 Fused magnesia grain 0-4 mm 71% by weight
Fused magnesia flour Floe graphite 10% by weight
Aluminum powder 3% by weight
Silicon powder 3% by weight
35
The binder is a phenolic resol which is added in an
amount of 3.1% by weight. The brick is pressed in the
customary formats for the cement industry (known as VDZ
formats) at a pressing pressure of 160 MPa and

- 10a -
subsequently heated at a temperature of 200°C. in this
case, fused magnesia is used since the stresses are
usually highest

- 11 -
in the lower transition zone. In the case of relatively
low stresses, the use of sintered magnesia is also
possible.
5 Here too, the installation of the bricks is carried out
using, the installation tools and methods customary in
the cement industry.
Sintering zone FP 12-3.0 m .
10
Lining is effected by means of a magnesia brick having
a graphite content of 10% by weight; the composition of
this brick is as follows:
15 Sintered magnesia grain 0-4 mm 48% by weight
Sintered magnesia flour Sintered spinel 0-4 mm 20% by weight
Floe graphite 10% by weight
Aluminum powder 3% by weight
20 Silicon powder 3% by weight
Silicon carbide powder 3% by weight
The binder is a phenolic resol which is added in an
amount of 3.1% by weight. The brick is pressed in the
25 customary formats for the cement industry (known as VDZ
formats) at a pressing pressure of 160 MPa and
subsequently heated at a temperature of 200OC. In this
case, sintered spinel is additionally used in order to
aid deposit formation and at the same time reduce the
30 thermal conductivity of the lining. Of course, the use
of fused magnesia and fused spinel is also possible.
Aluminum powder, silicon, powder and silicon carbide
powder serve as antioxidants to control sealing and
strengthen the microstructure,
35
Here too, the installation of the bricks is carried out
using the installation tools and methods customary in
the cement industry.

-12 –
Upper transition zone FP 30-43 in
Lining is effected in this example by means of a
magnesia brick having a graphite content of 10% by
5 weight; the composition of this brick is as follows:
Sintered magnesia grain 0-4 mm 48% by weight
Sintered magnesia flour Fused: ot-alumina 0-4 mm 20% by weight
10 Floc graphite 10% by weight
Aluminum powder 3% by weight
Silicon powder 3% by weight
Silicon carbide powder 3% by weight
15 The binder is a phenolic resol which is added in an
amount of 3,2% by weight. The brick is pressed in VDZ
formats at a pressing pressure of 160 MPa and
subsequently heated at a temperature of 2O0°C. In this
case, fused a-alumina is additionally used in order to
20 reduce the thermal conductivity of the lining. Of
course, the use of sintered a-alumina is also possible.
Aluminum powder, silicon powder and silicon carbide
powder serve as antioxidants to regulate sealing and to
strengthen the microstructure.
25
The installation of the bricks is carried out in a
manner analogous to the other bricks.
Safety zone FP 43-52 m
30
Lining is effected in this example by means of an
alumina-rich brick having a graphite content of 10% by
weight; the composition of this brick is as follows:
35 Flint clay 0-4 mm 6B% by weight
Ground flint clay Floc graphite 10% by weight
Aluminum powder 3% by weight
Silicon powder 3% by weight

-12a –
Silicon carbide powder 3% by weight
The binder is a phenolic resol which is added in an
amount of 3.4% by weight. The brick is pressed in A
5 formats (ISO formats)

- 13 -
at a pressing pressure of 160 MPa and subsequently
heated at a temperature of 200oC. Aluminum powder,
silicon powder and silicon carbide powder serve as
antibxidants to regulate sealing and to strengthen the
5 microstructure, in addition, silicon carbide increases
the resistance to alkali attack.
The installation of the bricks is carried out in a
manner analogous to the other bricks.
10
Preheating zone FP 52-75 m
Lining is effected in this example by means of a
lightweight chamotte brick having a graphite quantity
15 of 10% by weight; the composition of this brick is as
follows:
Lightweight chamotte 0-4 mm 63% by weight
Lightweight chamotte flour 20 Floc graphite 10% by weight
Aluminum powder 34% by weight
Silicon powder 3% by weight
Silicon carbide powder 3% by weight
25 The binder is a phenolic resol which is added in an
amount of about 3.8% by weight. The brick is pressed, in
A formats (ISO formats) at a pressing pressure of
120 MPa and subsequently heated at a temperature of
200CC. Aluminum powder, silicon powder and silicon
30 carbide powder serve as arttioxidants to regulate
sealing and to strengthen the microstructure. In
addition, silicon carbide powder increases the
resistance to alkali attack. The pressing pressure
selected is lower in this case, since high compaction
35 is not necessary for bricks in this region. In
particular cases, for example when the brick is
subjected to a high concentration of alkalis from the
furnace atmosphere, it is of course also possible to
use a more highly compacted brick for this purpose

- 13a - i
without problems.
The installation of the bricks is carried out in a
manner analogous to the bricks described above.

- 14 -
Example 2: Shaft kiln
A shaft kiln for line as is shown in cross section in
fig. 3 and in which lime stone is fired to produce CaO
5 under typical operating conditions is used as a
starting point. The height of the klin is 23 m, the
Internal diameter is 4.00 and the external diameter
is 5.20 m. The division, into zones as shown in fig. 4
is as follows (points of the furnace are counted front
10 the bottom) :
Inlet (preheating) zone FP 19.6 - 23 m
Sintering zone FP 1,4 - 19.6 m
Outlet (cooling) zone FP 0 - 1.4 m
15 In general, a calcium silicate tile lining
(thickness: 2 5 mm) is provided directly on the wall of
the kiln to insulate the shaft kiln thermally, followed
by a refractory brick lining (thickness: 64 mm) in the
direction, of the interior of the kiln, followed
20 subsequently by a lining with a lightweight refractory
brick (thickness; 124mm, typical density:
1.50 - 1.65 g/cm3) , then followed by a lining with a
typical chamotte brick (thickness: 124 mm, typical
density: 2.0 - 2.30 g/cn3) , and in the interior the
25 working lining of graphite-containing bricks employed
according to the invention. To compensate expansion
differences, a layes of Styropor is provided between
the graphite-containing bricks and the chamotte bricks.
30 Inlet (preheating) zone FP 19.6 - 23 m
Lining is effected in this example by means of a
chamotte brick having a graphite content of 10%; the
composition of this brick is thus as follows:
35
Chamotte 0-4 mm 63% by weight
Chainotte flour Floe graphite 10% by weight

- 14a -
Aluminum powder 3% by weight
Silicon powder 3% by weight
Silicon carbide powder 3% by weight
5
The binder is a phenolic resol which is added in an
amount of about 3.5% by weight. The brick is pressed in
A formats

- 15 -
(ISO formats) at a pressing pressure of 120 MPa and
subsequently heated at a temperature of 200°C. Aluminum
power, silicon powder and silicon carbide powder serve
as antioxidants and to strengthen the microstructure.
5 In addition, silicon carbide powder increases the
resistance to alkali attack. The pressing pressure
selected is lower in this case, since high compaction
is not necessary for bricks in this region. In
particular cases, for example when the brick is
10 subjected to a high concentration of alkalis from the
furnace atmosphere, it is of course also possible to
use a more highly compacted brick: for this purpose
without problems -
15 The installation of the briclts is carried out using the
installation tools and methods customary in the lime
industry.
Sintering zone FP 1.4 - 13,6 m
20
Lining is effected in this example by means of a
magnesia brick 1 having a graphite content, of 10%; the
composition of this brick is thus as follows:
25 Sinter magnesia grain 0-4 mm 71% by weight
Sintered magnesia flour Floc graphite 10% by weight
Aluminum powder 3% by weight
Silicon powder 3% by weight
30
In the case of increased stresses, for example due to
abrasive stress, it is also possible to use fused
magnesia in place of sintered magnesia. The binder is a
phenolic xesol which is added in an amount of 3.2% by
35 weight. The brick is pressed in A formats (ISO formats)
at a pressing pressure of 160 MPa and subsequently
heated at a temperature of 200°C.
The installation of the bricks is carried out using the

- 15a -
installation tools and methods customary in the line
industry.

-16 –
Outlet (cooling) zone FP 0 - 1.4 m
Lining is likewise effected in this example by means of
a chamotte brick (as in the inlet (preheating) zone)
5 having a graphite content of 10% by weight; the
composition of this brick is thus as follows:
Chamotte 0 - 4 mm 68% by weight
Chamotte flour 10 Floe graphite 10% by weight
Aluminum powder 3% by weight
Silicon powder 3% by weight
Silicon carbide powder 3% by weight
15 The binder is a phenolic resol which is added in an
amount of about 3,5% by weight. The brick is pressed in
A formats (ISO formats) at a pressing pressure of
120 MPa and subsequently heated at a temperature of
200°C. Aluminum powder, silicon powder and silicon
20 carbide powder serve as antioxidants. and to strengthen
the microstructure. In addition, silicon carbide powder
increases the resistance to alkali attack. The pressing
pressure selected is lower in this case, since high
compaction is not necessary for bricks in this region.
25 In individual cases, for instance in the case of high
abrasive stress, it is of course also possible to use a
more highly compacted brick Without problems.
The installation of the bricks is carried out using the
30 installation tools and methods customary in the lime
industry.
Preference is given to refractory bricks having the
following compositions;
35
Magnesia 25 - 98% by weight, in particular
27 - B3% by weight

- 16a -
Spinel mineral or 0 - 40% by weight, in particular
a-alumina 5 - 30% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2-8% by weight
Silicon powder 0 - 10% by weight, in particular
2 - B% by weight
Silicon carbide 0 - 10? by weight, in particular
Powder 3 - 7% by weight

- 17 -
Alumina-rich 50 - 98% by weight, in particular
Chamotte 57 - 83% by weight
Graphite 2 — 30% by weight, in particular
5 - 20$ by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 6% by weight
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3-7% by weight
Lightweight 50 - 98% by weight, in particular
Chamotte 57 - 88% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 9% by weight
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight

-17a-
Refratechnik Holding GmbH Nomember 15, 2003
PCT/EPO3/02248 M 6131 PCT/l/al
Main. claim
1. A Large-volume industry furnace in which mineral,
5 products, e.g. cement, lime, magnesite, dolomite or the
like, are fired in an essentially oxidizing furnace
atmosphere at temperatures above 700oC, wherein the
industry furnace comprises masonry composed of unfired
bricks of refractory material and the bricks in the
10 interior in the fire-side or hot-side surface region of
the masonry contain from 2 to 30% by weight of carbon,
with the carbon being present in the form of graphite
and in the form of carbon-containing binder and carbon-
containing binder being present in amounts of from 2 to
15 5% by weight.
AMENDED SHEET

- 18 -
Refratechnik Holding GmbH April l, 2004
M 6137 PCT/I/dl
Claims
2. An industrial furnace as claimed in claim 1,
5 characterized by bricks composed of refractory material
customarily used for such furnaces, which in the region
of the surface on the fire-side of the masonry have
carbon present in a zone, in particular in a zone
having a thickness of from 1 to 18 cm, preferably from
10 2 to 15 cm.
3, An industrial furnace as claimed in claim 1 3and/or
2, characterised in that the bricKs have the formats
customarily used.
15
4. An industrial furnace as claimed in one or more of
claims 1 to 3, characterized in that the carbon is
present in the bricks in the form of natural or
synthetic graphite.
20
5. An industrial furnace as claimed in claim 4,
characterized in that
AMENDED SHEET

- 19 -
the bricks comprise floc graphite.
6 An industrial furnace as claimed in claim 4 and/or
5, characterized in that the binder is tar and/or
5 pitch.
7. An industrial furnace as claimed in claim 4 and/or
5, characterized in that the bricks comprise synthetic
resin as binder,
10
8, An industrial furnace as claimed in claim 7,
characterised in that the bricks comprise phenolic
resin as binder.
15 9. An industrial furnace as claimed in claim 7,
characterized in that the bricks comprise phenolic
resin-novolak as binder.
10. An industrial furnace as claimed in one or more of
20 claims 1 to 9, characterized in that from 5 to 20% by
weight of graphite is present in the carbon-containing
zone of the bricks.
11. An industrial furnace as claimed in one or more of
25 claims 1 to 10, characterised in that the carbon-
containing binder is present in the bricks in amounts
or from 2.5 to 4% by weight.
12. An industiral furnace as claimed in claim 1 or in
30 one or more of claims 1 to 11, characterized in that
the carbon is homogeneously distributed in the entire
brick.
AMENDED PAGE

- 20 -
13. An industrial furnace as claimed in claim 12,
characterised in that the masonry is constructed of
bricks comprising, in particular, a basic refractory
material, in particular on the basis of Mgo.
5
14. An industrial furnace as claimed in claim 13,
characterized in that the masonry is constructed of
bricks in which MgO is at least partly replaced by
spinel and/or a-alumina and/or bauxite and/ox
10 andalusite and/or mullite and/or flint clay and/or
chamotte.
15. An industrial furnace as claimed in one Or more of
claims 1 to 14, characterized in that the bricks have a
15 porosity of less than. 30% by volume, in particular Less
than 14% by volume, preferably a porosity in the range
from 1 to 8% by vo]_volume.
16. An industrial furnace as claimed in one or more of
20 claims 1 to 15, characterized in that the bricks
comprise antioxidants known per se, in particular in
amounts of from 1 to 10% by weight, preferably in
amounts of from 2 to 8% by weight.
25 17. An industrial furnace as claimed in one or more of
claims 1 to 16 in a sintering zone and/or upper
transition zone of a rotary tube furnace or shaft kiln,
characterized by carbon-containing bricks based on MgO
and/or MgO/spinel mineral or MgO/bauxite or MgO/a-
30 alumina or MgO/zircronimn oxide.
18. An industrial furnace as claimed in claim 17,
characterized in that
AMENDED PAGE

-21 –
the bricks have the following composition:
Magnesia 25 - 98% by weight, in particular
27 - 83% by weight
Spinel mineral 0 - 4 0% by weight, in particular
5 - 30% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0-10% by weight/ in particular
2-8% by weight
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
powder 3-7% by weight
Binder 2 - 5% by weight, in particular
2,5-4% by weight
19, An industrial furnace as claimed in claim 17,
5 characterized by carbon-containing bricks based on
spinel or bauxite or a-alumina-
20. An industrial furnace as claimed in one or more of
claims 1 to 19 in a safety zone of a rotary tube
10 furnace or shaft kiln, characterized by carbon-
containing bricks based on andalusite or a mineral of
the sillimanite group or bauxite or alumina-rich
chamotte such as flint clay,
15 21. An industrial furnace as claimed in claim 20,
characterized by bricks of the following composition:
Alumina-rich 50 - 98% by weight, in particular
Chamotte 57 - 9 3% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 8% by weight
AMENDED PAGE

- 21a -
Silican powder 0 - 10% ^ -weight, in particular
2 - 6% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight
Binder 2 - 5% by weight, in particular
2.5 - 4% by weight
22. An industrial furnace as claimed in one or more of
claims 1 to 21 in a preheating zone of a rotary tube
5 furnace or shaft kiln, characterised by carbon-
containing bricks based on chamotte or lightweight
charnotte.
AMENDED PAGE

- 22 -
23. An industrial furnace as claimed in claim 22,
characterized by bricks of the following composition:
Lightweight 50 - 98% by weight, in particular
Chamotte 57 - 88% by weight
Graphite 2 - 301 by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight
Binder 2-5% by veight, in particular
2-5 - 4% by weight
5
24, An industrial furnace as claimed in one or more of
claims 1 to 23 in a lower transition zone or in an
outlet zone of a rotary tube furnace or shaft kiln,
characterised by carbon-containing bricks based on
10 bauxite or magnesia.
25. An industrial furnace as claimed in one or more of
claims 1 to 24, characterised by multilayer masonry in
which the carbon-containing bricks are located on the
15 hot side and bricks comprising an insulating material,
e.g. lightweight refractory bricks or chamotte bricks,
are located on the cold side.
26. A refractory brick for producing the masonry in an
20 industrial furnace as claimed in one or: more of claims
1 to 25, characterized by a one-piece structure
coinprising a carbon-containing hot-side zone 2 having a
brick composition as cLaimed in one or more of claims 1
to 24 and a thermally insulating zone 3 comprising a
25 thermally insulating material.
27, A refractory brick for producing masonry as

AMENDED PAGE

- 22a -
claimed in one or more of claims 17 to 19,
characterized by the following composition:
AMENDED PAGE

- 23 -
Magnesia 25 - 98% by weight, in particular
27 - 83% by weight
Spinel mineral or 0 - 40% by weight, in particular
a-alumina 5 - 30% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2-8% by weight
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight
Binder 2-5% by weight, in particular
2.5 - 4% by weight
28. A refractory brick for producing masonry as
claimed in claim 20, characterized by the following
5 composition:
Alumina-rich 50 - 98% by weight, in particular
Chamotte 57 - 88% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon powder 0 - 1D% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3-7% by weight
Binder 2-5% by weight, in particular
2.5 - 4% by weight
29. A refractory brick for producing masonry as
claimed in claim 22, characterized by the following
10 composition:
AMENDED PAGE

- 23a -
Lightweight 50 - 98% by weight, in particular
chaste 57 88% by weight
Graphite 2 -30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 -100% by weight
silicon powder 0 - 10% by weight, in particular
2 - 10% by weight
Sxlicon carbide 0- 10% by weight, in particular
powder 3 - 7% by weight
Binder 2 - 5% by weight, in particular
2.5 - 4% by weight
AMENDED PAGE

-24-
Refratechnik Holding GmbH March 5, 2003
Adalperostr. 82 M 613.7 PCT/I/ho
85737 Ismaning
Abstract
Refractory masonry in a large-volume industry furnace
in which mineral products, e.g, cement, Lime,
magnesite, dolomite or the like, are fired in an
essentially oxidizing furnace atmosphere at
temperatures above 700"C, wherein the masonry is
composed of unfired bricks of refracted material and
carbon is present in the fire-side or hot-side surface
region of the bricks of the masonry.
In addition, the invention relates to refractory bricks
for producing the masonry.

- 18 -
Refratechnik Holding GmbH March 5, 2003
Adalperostr. 82 M 6137 PCT/l/ho
85737 Ismaning
Claims
5 1. A refractory masonry in a lstge-volume industry
furnace in which mineral products, e.g. cement, lime,
matgnesite, dolomite or the like, are fired in an
essentially oxidizing furnace atmosphere at
temperatures above 700ºc, characterized in that the
10 masonry is composed of unfired bricks of refractory
material and carton is present in the fire-side or hot-
side surface region of the bricks of the masonry.
2. The masonry as claimed in claim 1, characterized
15 by bricks composed of refractory material customarily
used for such furnaces, which in the region of the
surface on the fire-side of the masonry have carbon
present in a zone, in particular in a zone having a
thickness of from 1 to 13 cm, preferably from 2 to
20 15 cm.
3. The masonry as claimed in claim 1 and/or 2,
characterized in that the bricks have the formats
customarily used.
25
4. The masonry as claimed in one or more of claims 1
to 3, characterised in that the carbon is present in
the bricks in the form of graphite.
30 5. The masonry as claimed in claim 4, characterized
in that the bricks comprise floc graphite.
AS ORlGINAlLY FILED

- 19 -
6. The masonry as claimed in claim 4 and/or 5,
characterized in that the bricks further comprise
carbon in the form of carbon-containing binder, e.g.
tar and/or pitch.
5
7. The masonry as claimed in claim 6, characterized
in that the bricks comprise synthetic resin as binder,
8. The masonry as claimed in claim 7, characterized
10 it that the bricks comprise phenolic resin as binder,
9. The masonry as claimed in claim 7, characterized
in that the bricks comprise phenolic resin-novolak as
binder,
15
10. The masonry as claimed in one or more of claims 4
to 9, characterized in that from 2 to 30% by weight, in
particular from 5 to 20% by weight, of carbon is
present in the carbon-containing zone or the bricks.
20
11. The masonry as claimed in one or more of claims 4
to 9, characterized in that the bricks contain from 2
to 5% by weight, in particular from 2.5 to 4% by
weight , of a carbon -containing binder.
25
12 The masnry as claimed in claim 1 or in one or
more of claims 3 to 11, characterized in that the
carbon is homogeneously distributed in the entice
brick.
AS ORIGINALLY FIELD

- 20 -
13. The masonry as claimed in claim 12, characterized
in that it is constructed of bricks comprising, in
particular, a basic refractory material, in particular
on the basis of MgO.
5
14. The masonry as claimed in claim 13, characterized
in that it is constructed of bricks in which MgO is at
least partly replaced by spinel and/or a-alumina and/or
bauxite and/or andalusite and/or mullite and/or flint
10 clay and/or chamotte.
15. The masonry as claimed in one or more of claims 1
to 14, characterized in that the, bricks have a porosity
of less than 30% by volume, in particular less than 14%
15 by volume, preferably a porosity in the range from 1 to
8% by volume.
16. The masonry as claimed in one or more of claims 1
to 15, characterized in that the bricks comprise
20 antioxidants known per se, in particular in amounts of
from 1 to 10% by weight, preferably in amounts of from
2 to 8% by weight.
17. The masonry as claimed in one or more of claims 1
25 to 16 in a sinering zone and/or Tapper transition zone
of a rotary tube furnace or shaft kiln, characterised
by carbon-containing bricks based on MgO and/or
MgO/spinel mineral or MgO/bauxite or MgO/a-alurnirta or
MgO/zirconium oxide.
30
18. The masonry as claimed in claim 17, characterized
in that the bricks have the following composition:
Magnesia 25 - 98% by weight, in particular
27 - 83% by weight
Spinel mineral 0 - -40% by weight, in particular
5 - 30% by weight
AS ORIGINALLY FILED

- 21 -
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2-8% by weight
Silicon powder 0 - 10% by weight, in particular
2-8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight
19. The masonry as claimed in claim 17, characterized
by carbon-containing bricks based on spinel or bauxite
5 or a-alumina.
20. The masonry as claimed in one or more of claims 1
to 19 in a safety zone of a rotary tube furnace or
shaft kiln, characterized by carbon-containing bricks
10 based on andalusits or a mineral of the sillimatite
group or bauxite or alumina-rich chamotte such as flint
clay.
21. The masonry as claimed in claim 20, characterized
15 by bricks of the following composition:
Alumina-rich 50 - 98% by weight, in particular
Chamotte 57 - 88% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon powder 0 - 10%'by weight, in particular
2 - 8% by -weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 1% by weight
22. The masonry as claimed in one or more of claims 1
to 21 in a preheating zone of a rotary tube furnace or
20 shaft kiln, characterised by carbon-containing bricks

AS ORIGINALLY FILED

-21a –
based on chamotte or lightweight chamotte.
23. The masonry as claimed in claim 22, characterized
by bricks of the following composition:
5
Lightweight 50 - 98% by weight, in particular
chamotte 51 - 88% by weight
Grapbite 2 - 30% by weighty in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 8% by weight
AS ORIGINALLY FILED

- 22 -
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3-7% by weight
24. The masonry as claimed in one or more of claims 1
to 23 in a lower transition zone or in an outlet zone
5 of a rotary tube furnace or shaft kiln, characterized
by carbon-containing bricks based on bauxite or
magnesia.
25. The masonry as claimed in one or more of claims 1
10 to 24, characterized by multilayer masonry in which the
carbon-containing bricks are located on the hot side
and bricks comprising an insulating material, e.g.
lightweight refractory bricks or chamotte bricks, ace
Located on the cold side.
15
26: A reitactory brick for producing masonry as
claimed in one or more of claims 2 to 11 and 13 to 25,
ctaracterized by a one-piece structure comprising a
carbon-containing hot-side zone 2 and a thermally
20 insulating zone 3 comprising a thermally insulating
material.
27. A refractory brick for producing masonry as
claimed in one or more of claims 17 to 13,
25 characterised by the following composition:
Magnesia 25 - 96% by weight, in particular
27 - 83% by weight
Spinel mineral or 0 - 40% by weight, in particular
a-alumina 5 - 30% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particulars
2-8% by weight
AS ORIGINALLY FILED

- 22a -
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight
28. A refractory bricK for producing masonty as
claimed in claim 20, characterized by the following
5 composition:
AS ORIGINALLY FLED

- 23 -
Alumina-rich 50 - 93% by weight;, in particular
Chamotte 57 - 38% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 3% by weight
Silicon powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
Powder 3 - 7% by weight
29. A refractory brick for producing masonry as
claimed in claim 22, characterised by the following
5 composition:
Lightweight 50 - 98% by weight. in particular
Chamotte 57 - 88% by weight
Graphite 2 - 30% by weight, in particular
5 - 20% by weight
Aluminum powder 0 - 10% by weight, in particular
2 - 8% by weight
Silicon powder 0 - 104 by weight, in particular
2 - 8% by weight
Silicon carbide 0 - 10% by weight, in particular
powder. 3-7% by weight
AS ORIGINALLY FLED

in which mineral products, e.g, cement, Lime,
magnesite, dolomite or the like, are fired in an
essentially oxidizing furnace atmosphere at
temperatures above 700"C, wherein the masonry is
composed of unfired bricks of refracted material and
carbon is present in the fire-side or hot-side surface
region of the bricks of the masonry.
In addition, the invention relates to refractory bricks
for producing the masonry.

Documents:

00987-kolnp-2005-abstract.pdf

00987-kolnp-2005-claims.pdf

00987-kolnp-2005-description complete.pdf

00987-kolnp-2005-drawings.pdf

00987-kolnp-2005-form 1.pdf

00987-kolnp-2005-form 3.pdf

00987-kolnp-2005-form 5.pdf

00987-kolnp-2005-international publication.pdf

987-KOLNP-2005-ABSTRACT 1.1.pdf

987-kolnp-2005-assignment.pdf

987-kolnp-2005-assignment1.1.pdf

987-KOLNP-2005-CANCELLED PAGES.pdf

987-KOLNP-2005-CLAIMS 1.1.pdf

987-KOLNP-2005-CORRESPONDENCE 1.1.pdf

987-KOLNP-2005-CORRESPONDENCE 1.2.pdf

987-KOLNP-2005-CORRESPONDENCE 1.4.pdf

987-KOLNP-2005-CORRESPONDENCE 1.5.pdf

987-kolnp-2005-correspondence.pdf

987-kolnp-2005-correspondence1.6.pdf

987-KOLNP-2005-DESCRIPTION (COMPLETE) 1.1.pdf

987-KOLNP-2005-DRAWINGS 1.1.pdf

987-KOLNP-2005-FORM 1.1.1.pdf

987-kolnp-2005-form 18.1.pdf

987-kolnp-2005-form 18.pdf

987-KOLNP-2005-FORM 2.pdf

987-KOLNP-2005-FORM 3.1.1.pdf

987-kolnp-2005-form 3.2.pdf

987-kolnp-2005-form 5.pdf

987-kolnp-2005-gpa.pdf

987-kolnp-2005-gpa1.1.pdf

987-kolnp-2005-granted-abstract.pdf

987-kolnp-2005-granted-claims.pdf

987-kolnp-2005-granted-description (complete).pdf

987-kolnp-2005-granted-drawings.pdf

987-kolnp-2005-granted-form 1.pdf

987-kolnp-2005-granted-form 2.pdf

987-kolnp-2005-granted-specification.pdf

987-kolnp-2005-intenational publication.pdf

987-kolnp-2005-international preliminary examination report.pdf

987-kolnp-2005-international search report.pdf

987-KOLNP-2005-OTHERS.pdf

987-kolnp-2005-pct request form.pdf

987-KOLNP-2005-PETITION UNDER RULE 137.pdf

987-KOLNP-2005-REPLY TO EXAMINATION REPORT.pdf

987-kolnp-2005-reply to examination report1.1.pdf

987-kolnp-2005-translated copy of priority document.pdf

987-kolnp-2005-translated copy of priority document1.1.pdf

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Patent Number

250677

Indian Patent Application Number

987/KOLNP/2005

PG Journal Number

03/2012

Publication Date

20-Jan-2012

Grant Date

18-Jan-2012

Date of Filing

26-May-2005

Name of Patentee

REFRATECHNIK HOLDING GMBH

Applicant Address

ADALPEROSTR, 82, 85737 ISMANING

Inventors:

#	Inventor's Name	Inventor's Address
1	KLISCHAT HAMS-JURGEN	AM WESTERBERG 6, 37130 GLEICHEN
2	FERNANDEZ ANTONIO	C/FCA ESCROVA N°2-PISO 2°, PUERTA 3, ELPERELLO(SUECA), 46420 VALENCIA
3	WIRSING HOLGER	STETTINER STRASSE 31, 37083 GOTTINGEN

PCT International Classification Number

F27D 1/00

PCT International Application Number

PCT/EP2003/002248

PCT International Filing date

2003-03-05

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	PCT/EP2003/002248	2003-03-05	IB