DE4221480A1 - METHOD AND MIXTURE FOR FORMING A MATERIAL FIRE-RESISTANT MASS ON A SURFACE - Google Patents

Abstract

A process for forming a coherent refractory mass on a surface based on a silicon compound comprises projecting against the surface, simultaneously with oxygen, a mixture comprising refractory particles and combustible particles which react in an exothermic manner with the projected oxygen by releasing sufficient heat to form the mass, under the action of heat of combustion. The mixture comprises combustible silicon particles, refractory particles of one or a plurality of substances which constitute the major portion by weight of the mixture, as well as particles of 1) another substance and/or 2) non-metallic particles whose composition is such that, during the formation of the mass, they generate the other substance, which other substance causes the incorporation of silica, formed by the combustion of the silicon particles, into a crystalline lattice. Substance 1) is preferably magnesia, calcium oxide or iron (II) oxide and 2) may be calcium peroxide or wollastonite.

Description

The invention relates to a method for molding a coherent refractory mass on a surface, at the same time with oxygen against this surface a mixture of refractory particles and combustible part which is thrown in an exothermic manner the ejected oxygen by releasing enough heat to form the aforementioned refractory mass react under the effect of combustion heat. The invention also relates to a particle mixture which for a method of forming a coherent one Refractory mass is determined on a surface by the mixture and oxygen floated against the surface dert, wherein the mixture refractory particles and Contains particles of a combustible substance, the exothermic reaction with oxygen to release enough heat are suitable to under the effect of Combustion heat the aforementioned refractory mass to form.

If you put in situ a refractory mass on a surface one can distinguish between two known principles len procedure.

According to the first of these methods, sometimes as so-called named "ceramic welding", which in the British Patent 13 30 894 (Glaverbel) and the British patent 21 70 191 is a coherent Refractory mass on a surface by flinging a mixture of refractory particles and combustible Particles in the presence of oxygen on the Shaped surface. The combustible particles are  Particles, their composition and granulometry such are that they are in an exothermic way with the oxygen during the formation of a refractory oxide and during the Release the necessary heat to melt, little at least superficially, the ejected refractory par respond. Aluminum and silicon are examples for such combustible substances. It is known that Silicon, strictly speaking, classified as a semi-metal but silicon, like certain metals, has to be behaves (it is able to do a considerable exothermic oxidation during the formation of a refractory oxide to undergo), these combustible elements are called so-called combustible metallic substances of the For simplicity's sake. In general it will recommended the spinning of the particles in the presence a high oxygen concentration, eg. B. by use of commercially available quality oxygen as one Gas carrier to perform. That way, one becomes coherent refractory mass formed on the Surface to which the particles are thrown adheres. Due to the very high temperatures that the can achieve ceramic weld reaction, it can Slag penetrate on the surface of the Refractory substance that is treated to be present can, and she can so soften the surface or melt, that a good connection between the treated surface and the newly formed refractory mass will be produced.

These known ceramic welding methods can be used for Forming a refractory article, z. B. a block, be used with a special look, but they be very much for the formation of coatings or for Repair of bricks or walls used, and they are especially useful for repair or strengthening  existing refractory structures, z. B. for repairing Walls or coatings for refractory facilities, such as Melting furnace walls in glassmaking or coke ovens.

This procedure is generally carried out when the refractory carrier is hot. This makes it possible while repairing eroded refractory surfaces the device essentially at its Betriebstempe and, in certain cases, even during their business.

The second known process for forming a refractory mass on a surface is the so-called "flame It involves directing a flame upwards the place where a refractory mass is to be formed and Spray refractory powder across this flame. The flame is caused by a gaseous fuel or a liquid or even fed by coke powder. It it is plausible that the efficient use of this Flammsprühtechnik a complete burning of the Fuel requires the hottest flame, the is possible to generate and for maximum efficiency too achieve. In general, that is with the flame spray Procedure obtained flame temperature not so hot like the one achieved with ceramic welding technology with the result that the coherence or the Relation of shaped refractory mass not so good is, and there the connection between the new refractory mass and the surface of the refractory carrier at one low temperature has been formed, this is Connection not so permanent. Moreover, such is one Flame less suitable than a ceramic weld Reaction to penetrate the slag on the Refractory surface to be treated available can be.  

The composition of the mixture, which in a kera Mixing welding process is used commonly selected in the manner to produce a repair mass pose similar or a chemical composition near the refractory carrier. This contributes to it at, compatibility and adhesion with the new Material and the vehicle on which it is molded, for sure deliver.

However, it has been found that problems occur when It is desirable to have certain types of refractory structures to repair and this even if a refractory mass a chemical composition is shaped similar which is the carrier refractory mass.

For example, fixing refractory top creates surface structures with a silicon carbide support with the Help of a mixture that is primarily carbon Silicon particles and also particles of metallic contains combustible substances, such as aluminum and Silicon particles, a refractory mass that is not always shows a sufficient adhesion to the refractory carrier.

Refractory materials with a silicon carbide carrier are used in certain metallurgical facilities, ins special in blast furnaces in the iron industry or in Zinc distillation columns, used. During operation This facility allows certain parts of the refractory struk a fairly low, minimal operation temperature, z. On the order of 700 ° C, and they can also be significant Be subjected to fluctuations in the ambient temperature. It was observed that by known techniques manufactured refractory masses on these parts of the Refractory structures do not always have a sufficient adhesion  at the refractory carrier mass, and in certain Cases, especially when repairing a block or is performed on a refractory wall whose Temperature is low, the new refractory mass dissolves completely from the carrier refractory and dissolves even during the operation of the facility.

Similar problems arise when one refractory Struk with a high-density silica support (so called to replace traditional silica Refractory masses to distinguish their density lower is) to repair that in certain coke ovens be used; even if you use a refractory material similar chemical composition compared to the Can form carrier refractory mass, the new mass sticks not always enough and can even move quickly Peel off the carrier refractory mass when the oven is in Operation is.

From International Patent Application WO 90/03 848 (Willmet / Willard) is a repair procedure for z. B. furnace linings known in which an inert gas and particles of a refractory oxide and combustible oxidizable material supplied to a flame spraying apparatus be, with high pressure sucks oxygen and the Carrier gas / particle mixture accelerates. Willart turns this procedure on the repair of refractory Blocks / bricks in the blow molding line of a copper smelt converters as well as in the repair of silicon car bid column bottoms. For example, you hurl one Mixture of 79% silicon carbide, 16.25% silicon, 4% aluminum and 0.75% magnesium by a double Venturi air-oxygen system on a silicon carbide co lonnenboden.  

However, the use of magnesium metal powder in This method is disadvantageous, at least in that Magnesium metal is relatively volatile; there is a measure uncertainty about the composition of the molded Refractory coating.

The object of the invention is therefore the aforementioned To solve problems and the disadvantages of the state of the art Technology to avoid.

This object is achieved by the kenn characterizing features of claims 1 and 10, respectively.

The dependent claims contain advantageous embodiment forms of the invention.

The invention therefore relates to a method for shaping a coherent refractory mass on one Surface based on a silicon compound, in which against the surface simultaneously with oxygen Mixture of refractory particles and combustible particles is thrown in an exothermic manner with the ejected oxygen by releasing enough Heat to form the refractory mass under the effect the heat of combustion react, the mixture contains: (i) combustible silicon particles; (ii) fire solid particles of one or a plurality of substances as a major part of the mixture; and (iiia) additional Liche particles of another substance during the Forming the refractory mass incorporating silicon oxide, which is formed by burning the silicon particles is brought into a crystalline lattice, and / or (iiib) additional particles of a non-metallic compound, the others during the formation of the refractory mass Substance brings about the incorporation of the by the  Combustion of silicon particles shaped silicon oxide into a crystalline lattice.

The invention also relates to a particle mixture which are intended for a method of molding one together hanging refractory mass on a surface based a silicon compound in which the mixture and acid fabric are thrown against this surface, wherein the mixture refractory particles and combustible particles which are capable of being exothermic with oxygen Respond to enough heat to form this refractory mass released under the influence of the heat of combustion set, which is characterized in that the Mixture contains: (i) combustible silicon particles; (ii) refractory particles of one or a plurality of Substances as a major weight fraction of the mixture; and (iiia) additional particles of another substance, the during the molding of the refractory mass the incorporation of silica produced by burning the silicon formed into a crystalline lattice, and / or (iiib) additional particles of one metallic compound, which during the formation of the Refractory mass will bring forth that other substance that the incorporation of silica produced by Ver combustion of the silicon particle is formed in a causes crystalline grid.

Such a mixture and method are useful for forming high-refractory masses Quality for the repair of surfaces based on a Silicon compound, such as. B. refractory structures of Ovens, as well as for welding together fragments. It is possible to get a refractory mass, the one Excellent adhesion to the carrier refractory material shows when the repaired surface repeated  Changes in thermal conditions during the Operation of the facility is suspended and / or if the Repair is carried out on a surface whose Temperature is relatively low, as between 600 ° C and 1000 ° C (eg 700 ° C), although the invention relates to surfaces applicable with a temperature outside this range is.

The masses prepared according to the invention show thermal expansion properties at the interface between the surfaces and the molded refractory mass, that are different from the ones you are could get if the starting mixture is not any Contains substance that incorporation of Silica produced by the combustion of silicon is shaped, effected in a crystalline lattice. It will assumed that the achieved by the invention Benefits at least partly due to this difference in the Is due to the interface and that the obtained Refractory masses thermal expansion properties show the interfaces that are good to those of Question standing refractory structures are adapted.

The combustible silicon particles (i) may be used as the sole combustible material can be used or they can with particles of another combustible mate rials, such as aluminum. Thus that contains Mixture preferably further combustible aluminum particles. Aluminum particles can quickly with a significant heat release, and they are oxidized form refractory oxides themselves. The application of this essential feature thus favors the formation of Refractory masses with high quality.  

The mixtures according to the invention preferably contain not more than 15% by weight of silicon. This is important to Limiting the amount of unreacted silicon found in the shaped refractory mass remains behind. It was found that the presence of unreacted Silicon in the molded refractory mass the procures may affect it.

The refractory particles (ii) may be used in an amount of at least 70% by weight, preferably at least 75% by weight, to be present to a homogeneous mass receive.

Make the additional particles (iiia) and / or (iiib) preferably the rest of the mixture and can be up to 25% by weight in the mixture, preferably from 5 to 15%, be included.

The combustible particles used in the mixture (i) preferably have an average particle size less than 50 μm.

The refractory particles (ii) preferably contain in essentially no particles larger than one size 4 mm, more preferably not larger than 2.5 mm, around the Forming a regular powder jet easier.

The additional particles (iiia) and / or (iiib) used in used in the mixture preferably have one Particle size of less than or equal to 500 microns. If Particles that are too large are used Risk that they do not play an effective role. Vorzugswei These particles have a size of at least 10 μm. When particles that are too small are used a risk that they evaporate during the reaction.  

Various substances are during the formation of the Refractory mass for inducing the incorporation of at Combustion of silicon-formed silica into a crystalline grid suitable.

The aforementioned additional substance (iiia) containing the Incorporation of silica by combustion is formed by silicon, in a crystalline lattice is preferably added to the mixture in the form of Magnesium oxide particles introduced.

The presence of this compound in the mixture, the thrown onto the refractory surface to be repaired will help ensure that the correct fire resistant properties of the molded refractory mass are ensured.

Moreover, the incorporation of magnesium oxide in the allowed Mixture the forming of a refractory mass, in which a Part of the formed by the combustion of silicon Silica in a crystalline lattice of Forsterittyps is installed. This also contributes to the correct fire resistant properties of molded To ensure refractory mass.

When the mixture is both aluminum and magnesia can be formed, a refractory mass, in which a part of at least that due to the combustion of silicon formed silica in a crystalline lattice of Forsterite structure and / or in a crystalline lattice Spinel structure and / or in a crystalline lattice Cordierite structure is incorporated.

The presence of a crystalline lattice of Carries cordierite structure in the molded refractory mass  to, an excellent resistance to thermi to ensure that this mass is impacted. The presence a crystalline lattice of the forsterite structure and / or Spinel structure on the other side affects in preferably the heat resistance of the molded Refractory mass.

Other oxides, such as calcium oxide or ferrous oxide, can also be used as the additional substance (iiia), the incorporation of by the combustion of Silicon-formed silica in a crystalline lattice causes.

A particle mixture can be used, in addition or alternatively an additional substance or substances (iiib) contains, whose composition is such, if the The refractory mass is shaped to be a substance which brings about the incorporation of through the Combustion of silicon-formed silica into a causes crystalline grid. For example, peroxides, such as calcium peroxide, nitrides, carbides.

An oxide, for. Calcium oxide, may be in the form of a compound, e.g. In the case of calcium oxide, in the form of wollastonite (CaO.SiO ₂ ).

The invention is particularly useful for the repair of Refractory materials with a silicon carbide carrier or Refractory materials with a high-density silicon oxide carrier. In a consistent way it will be for the ceramic welding prefers that it with the help of a Mixture is carried out, its main weight part Silicon carbide or silica exists.  

It goes without saying that the invention also for the repair of other types of refractory er useful on a silicon compound, like those mentioned before, like normal silicon oxide brick and silica-alumina brick, based.

The substance or substances that make up the main weight part the mix can be combined with the composition of the Refractory product which one wants to repair, correspond, or they can come from one be different substance. In the latter case will molded a refractory mass that have properties that may differ from and ideally improved over those of the refractory Er to be repaired certificates, z. B. improved strength Wear or improved refractory properties.

The invention will now be described by way of the following examples explained in more detail.

example 1

A refractory mass is placed on a wall of zinc destilla formed tion column. The wall contains bricks a silicon carbide carrier. A mixture of refractory part particles of a combustible substance, the exothermic oxidizable by forming a refractory oxide are, and from magnesia particles, will be on this Brick flung. The temperature of the wall is 800 ° C. The mixture is at the rate of 60 kg / h in one Stream of pure oxygen thrown. The mixture has the following composition:  

SiC 79% by weight Si 8th% al 5% MgO 8th%

The silicon particles have a dimension below 45 microns and a specific surface area between 2500 and 8000 cm ² / g is included. The aluminum particles have a size below 45 microns and a specific surface area between 3500 and 6000 cm ² / g is included. The dimension of the silicon carbide particles is less than 1.47 mm at 60% by weight from 1 to 1.47 mm, 20% from 0.5 to 1 mm, and 20% below 0.125 mm. The MgO particles have an average dimension of approximately 300 μm. "Average dimension" refers to a dimension such that 50% by weight of the particles have a smaller dimension than this average.

The wall repaired in this way becomes significant Subjected to fluctuations in ambient temperature, and it It is observed that the new refractory mass is permanent adheres to the carrier.

The structure of the shaped mass is under the microscope examined. An excellent continuity will be between the new refractory mass and the refractories bulk carrier detected. It is also stated that the silicon oxide formed by the combustion of silicon in the crystalline lattice of forsterite, cordierite and aluminum-containing spinel is incorporated.

For comparison purposes, a mixture that is not magnesium oxide, spun under the same conditions. The composition of this mixture is as follows:  

SiC 87% by weight Si 12% al 1%

It was observed that the shaped refractory mass turned out quickly separated from the wall and itself in solid blocks replaces when the zinc distillation column continues to work.

In a modification of this example, the mixture is ver used to repair the bottom of a coke oven, the made of normal silica bricks and silica Shaped aluminum oxide bricks. You get one Repair compound with good resistance to wear, that sticks well to the wall, even if they are different undergoes thermal changes.

Example 2

As a variation of Example 1, a mixture with the used the following context:

SiC 82% by weight Si 8th% al 5% MgO 5%

The wall being repaired contains bricks with one Silicon carbide carrier, and it has a temperature of 700 ° C on.

The resulting refractory mass also adheres permanently on the wall.

Example 3

The goal is to create a refractory mass on a wall of a To form coke oven, the high-density silica brick contains. While the apparent density of tra traditional silica bricks of the order of  1.80 is the apparent density of high density Bricks approx. 1.89. Such bricks are on recently appeared on the market for refractory material, these being Brick advantageous properties compared to tradi ionic silica bricks, noteworthy in Regarding their properties of gas permeability and thermal conductivity.

The repair is carried out on a wall whose Temperature is approximately 750 ° C, with the help of the following mixture:

SiO₂ 80.5% by weight Si 11.1% al 1% MgO 7.4%

The dimension of the SiO ₂ particles is less than 2 mm, with a maximum of 30 wt .-% of 1 to 2 mm and less than 15 wt .-% below 100 microns.

The formed mass adheres permanently to the wall.

In contrast, managed under the same Betriebsbe conditions a similar mixture, but no magnesium contains oxide, a refractory mass that differs slightly from the wall separates when they are different thermal Subjected to conditions that exist when the Oven is in operation.

Example 4

The goal is to create a refractory mass on a wall of a Coke oven made from a refractory material based on a silicon compound, wel  significant changes in ambient temperature is subjected and its temperature does not exceed 900 ° C increases. The repair is done on a wall, whose temperature is approximately 750 ° C, with the help of following mixture:

SiO₂ 80% by weight CaO · SiO₂ (wollastonite) 8th% Si 8th% al 4%

The average dimension of wollastonite particles is about 300 microns. The metal particle size corresponds to that in Example 1 and the silica particle size corresponds to that given in Example 3.

Claims (18)

Anspruch [en] A method of forming a coherent fire solid mass on a silicon compound-based surface in which a mixture of refractory particles and combustible particles are simultaneously thrown against the surface in an exothermic manner with the ejected oxygen by release of sufficient heat to form the refractory mass under the action of the heat of combustion, characterized in that the mixture contains:

• (i) combustible silicon particles;
• (ii) refractory particles of one or a plurality of substances as a major part of the weight of the mixture; and
• (iiia) additional particles of another substance which, during the formation of the refractory mass, cause the incorporation of silica formed by the combustion of the silicon particles into a crystalline lattice, and / or
• (iiib) additional particles of a non-metallic compound which during formation of the refractory mass produces this other substance which causes the incorporation of silica formed by the combustion of the silicon particles into a crystalline lattice.

2. Method of forming a refractory mass according to Claim 1, characterized in that this Substance (iiia) involving the incorporation of silicon oxide, due to the combustion of silicon particles is shaped into a crystalline lattice, in the mixture in the form of magnesium oxide particles is introduced. 3. A method of forming a refractory mass according to Claim 2, characterized in that at least a part of the silica that is produced by the combustion of silicon, into a crystalline git the forsterite structure is incorporated. 4. A method of forming a refractory mass according to one of claims 1 to 3, characterized in that that these combustible particles (i) continue Aluminum particles included. 5. A method of forming a refractory mass according to Claims 2 and 4, characterized in that at least part of the burning of the Silicon-formed silica into a crystalline one Grid of forsterite structure and / or in one crystalline lattice of the spinel structure and / or in a crystalline lattice of the cordierite structure is inserted is working. 6. A method of forming a refractory mass according to any of the preceding claims 1 to 5, characterized in that these non-metallic Compound (iiib) in the mixture in the form of Particles of a peroxide or a silicate is introduced.   7. A method of forming a refractory mass according to one of claims 1 to 6, characterized that these refractory particles (ii), the Hauptge make up the proportion by weight of the mixture, silicon carbide particles are. 8. A method of forming a Feuerst mass according to one of claims 1 to 6, characterized that these refractory particles (ii) containing the Make up the main weight fraction of the mixture, Silica particles are. A method according to any preceding claim, characterized in that the temperature of the upper area is less than 1000 ° C. A particulate mixture intended for a method of forming a continuous refractory mass on a silicon compound surface in which the mixture and oxygen are spun against that surface, the mixture containing refractory particles and combustible particles for exothermic reaction with oxygen to release sufficient heat to form, under the effect of heat of combustion, this refractory mass, characterized in that the mixture contains:

• (i) combustible silicon particles;
• (ii) refractory particles of one or a plurality of substances as a major part of the weight of the mixture; and
• (iiia) additional particles of another substance which, during the formation of the refractory mass, causes incorporation of silica formed by combustion of the silicon particles into a crystalline lattice, and / or
• (iiib) additional particles of a nonmetallic compound which, during the formation of the refractory mass, produce that other substance which causes the incorporation of silica formed by the formation of the silicon particles into a crystalline lattice.

11. Mixture according to claim 10, characterized that this mixture magnesium oxide particles as these Contains particles of the other substance (iiia). 12. Mixture according to claim 10 or 11, characterized marked records that this mixture particles of a peroxide or a silicate than these non-metallic ones Contains compound (iiib). 13. Mixture according to one of claims 10 to 12, characterized characterized in that these combustible particles (i) further contain aluminum particles. 14. Mixture according to one of claims 10 to 13, characterized characterized in that these refractory particles (ii), that make up the bulk of the mix Silicon carbide particles are. 15. Mixture according to one of claims 10 to 13, characterized characterized in that the refractory particles (ii), the  make up the main weight fraction of the mixture, Silica particles are. 16. Mixture according to one of claims 10 to 15, characterized characterized in that these additional particles (iiia) or (iiib) has a particle size of less than or equal to 500 microns have. 17. A mixture according to any one of claims 10 to 16, characterized in that the additional particles (iiia) or (iiib) has a particle size of at least 10 microns. 18. A mixture according to any one of claims 10 to 17, characterized in that the silicon content is therein not more than 15% by weight.