MXPA00007947A - Tap hole blocking material for metal melting apparatus - Google Patents

Abstract

A tap hole blocking material for a metal melting apparatus which comprises (a) a refractory aggregate having a maximum particle size of 5 mm or less, (b) graphite and silicon nitride each having a maximum particle size of 0.2 mm or less, (c) a refractory clay, (d) a compatible binder comprising a phenol resin, a ketone compound and a pitch and (e) an organic fine fiber.

Description

COMPOSITION OF PIQUERA PLASTERING FOR METAL FONDER APPARATUS TECHNICAL FIELD The present invention relates to runner plugging compositions for metal melting apparatus.

PREVIOUS TECHNIQUE 10 Pike (mud) plugging compositions are prepared by kneading a mixture comprising a refractory aggregate such as alumina, silicon carbide, bauxite, mullite, chamotte, pyrophyllite or coke, using a binder such as tar or phenolic resin. The The compositions are used to stop, when necessary, the casting of molten metal by closing pits through which the molten metal is discharged from an apparatus for melting metal. After a certain period of casting obstruction, a runner for molten metal is formed through the compositions, so that the casting can be easily restarted. Thus, The runner plugging compositions need to have various properties as described below. Typically, a runner is filled with a runner plugging composition using an extrusion tool called an 1-iÍÉ & ^ - ^^^^^ injection nozzle. Without sufficient plasticity, the plugging composition is unable to be extruded from the injection nozzle or unable to sufficiently plug the runner, stopping the pouring. In this way, the casting composition is required to have adequate plasticity and reach a suitable density after plugging. In addition, it is required that the plugging composition has, when filled in a runner, properties to be rapidly sintered (sinterability) by heat in the metal melting apparatus (furnace) and a sufficient sintering force to prevent spillage of the molten metal. A corking composition with poor sinterability does not sufficiently stop the casting and the molten metal will spill and cause problems. In addition, the plugging composition needs to have a high porosity (high gas permeability) after sintering, because the binder gasifies rapidly during solidification of the composition and is liable to cause the composition to disintegrate or get lumpy. After a certain period of casting clogging, a hole is drilled through the sintered plugging composition using a drill to restart the casting. When the composition has an excessively high sintering force (strength after solidification), it will take time to drill a hole through the composition. Therefore, the composition needs to have an adequate sintering force. In addition, low contaminant properties are also important for the plugging composition, since smoke or dust is produced during drilling. In addition, since the molten metal passes through the drilled hole, it is required that the sintered plugging composition have sufficient strength and corrosion resistance to withstand contact with the molten metal and a good bond strength to the forming bricks. the wall of the runner. If these properties are insufficient, the diameter of the perforated hole is increased and the molten metal discharges in a dispersed manner, making the laundry unstable. In the worst case, the oven must be closed before the laundry is finished. As binders for the corking composition, tars and pitches have been used for a long time because they are not expensive. "Tar" is an oily and viscous black or dark brown bituminous material produced by heat treatment or by pyrolysis of organic materials such as coal or wood. Tars include coal tars (oils produced by dry coal distillation), shale tars (oils produced by dry distillation of oil shale), wood tars, gas tars (oils produced as petroleum gasification byproducts), petroleum tar (a generic name for vaporization or petroleum distillation residues or their including pyrolyses, including petroleum asphalt, distillation residue, pyrolysis tar and the like) . "Brea" is a black carbonaceous solid residue obtained by heat treatment or pyrolysis (eg, distillation such as dry distillation) of organic materials. When a tar or pitch is used as a binder for the plugging composition, the resulting composition has good adhesion to the bricks that form the wall of the runner, but it takes a long time to sinter and is therefore liable to cause such problems like leak of molten metal. In addition, tars and pitches present a serious problem of heavy smoke and dust produced at the time of plugging or opening the runner. Phenolic resins are also used as binders for the tamponade composition. A plugging composition prepared using a phenolic resin has a fast-drying characteristic (rapid volatility of liquid components) and a high sintering force. However, due to the excessively high sintering force, it is difficult to drill a hole through the composition. In addition, because the phenolic resins are expensive, a plugging composition prepared using a phenolic resin is less economical than that prepared using inexpensive tars. Recently, a combined use of a phenolic resin and a pitch has been developed, since each of those binders has favorable properties, as described above. However, a plugging composition comprising these binders in combination is not sufficient in gas permeability (porosity) and bond strength to the bricks that form the furnace wall. The main object of the present invention is to solve or significantly improve the aforementioned problems of the prior art, by providing a runner plugging composition (mud) which fully shows favorable properties of a pitch and a phenolic resin used as binders and which are excellent in gas permeability and adhesion strength.

DETAILED DESCRIPTION OF THE INVENTION The present inventors conducted extensive research to achieve the above object and found that a runner plugging composition (mud) comprising the components shown below, has excellent properties. The present invention provides the following runner plugging compositions: A. A runner plugging composition for metal melting apparatus, comprising (a) refractory aggregate having a maximum particle size of 5 mm or less, (b) graphite and silicon nitride, each having a maximum particle size of 0.2 mm or less, (c) a refractory clay, (d) a compatibilized binder mixture comprising a phenolic resin, a ketone compound and a pitch and (e) an organic fine fiber.

B. A runner plugging composition according to point A wherein the refractory aggregate (a) is at least one element selected from the group consisting of alumina, high alumina, silicon carbide, bauxite, mullite, chamotte, pyrophyllite, coke , zirconia, ferrosilicon and magnesia. C. A runner plugging composition according to point A, wherein the compatibilized binder mixture (d) has a pitch content of 0.5 to 30 parts by weight per 100 parts by weight of the binder mixture. D. A runner plugging composition according to point A, wherein the organic fine fiber (e) is at least one element selected from the group consisting of polyester fibers, polyvinyl alcohol fibers, acrylic fibers, chloride fibers of polyvinyl, acetate fibers, rayon fibers, polyamide fibers, polyethylene fibers, polypropylene fibers, polyurethane fibers and polyvinylidene chloride fibers. E. A runner plugging composition according to point A, wherein the organic fine fiber (e) has a fiber diameter of 5 to 200 μm and a fiber length of 3 to 15 mm. F. A runner plugging composition according to point A, which comprises 100 parts by weight of a refractory powder consisting of 60 to 85 parts by weight of the refractory aggregate (a), 5 to 30 parts by weight of the graphite and silicon nitride (b) and 5 to 15 parts by weight of the refractory clay (c); 15 to 25 parts by weight of the compatibilized binder mixture (d) relative to 100 parts by weight of the refractory powder; and 0.01 to 0.75 parts by weight of the organic fine fiber (e) relative to 100 parts by weight of the refractory powder. The composition of the invention is a plugging composition (mud) for tappers of apparatus for melting metal and comprises (a) a refractory aggregate having a maximum particle size of 5 mm or less, (b) graphite and silicon nitride, each having a maximum particle size of 0.2 mm or less, (c) a refractory clay, (d) a compatibilized binder mixture comprising a phenolic resin, a ketone compound and a pitch and (e) an organic fine fiber. Each of the components will be described in detail later. (a) Refractory Aggregate The refractory aggregate for use in the present invention has a maximum particle size of about 5 mm or less, preferably about 4 mm or less, more preferably about 3.5 mm or less. A refractory aggregate is also usable in which the proportion of particles having a particle size of 1 to 4 mm is not more than 40%. Any refractory aggregate used conventionally in this technical field can be used in the invention without limitation. Usable refractory aggregates include alumina, high alumina, silicon carbide, bauxite, mullite, chamotte, pyrophyllite, coke, zirconia, ferrosilicon and magnesia. Among these aggregates, alumina, high alumina, silicon carbide, bauxite, mullite, chamotte, pyrophyllite and coke are preferred, among which alumina, high alumina, silicon carbide, bauxite and coke are most preferred. These aggregates can be used alone or in combination. (b) Graphite and silicon nitride It is essential for the present invention to use graphite and silicon nitride in combination. The graphite and silicon nitride for use in the invention each have a maximum particle size of about 0.2 mm or less, preferably about 0.15 mm or less, more preferably about 0.125 mm or less. You can also use graphite and silicon nitride in each of which, the proportion of particles that have a particle size of 0.125 to 0.044 mm is not more than 40%. If the graphite has an excessively large maximum particle size, the resulting plugging composition exhibits reduced lubricity during extrusion from the injection nozzle and is liable to be extruded in an insufficient amount. Furthermore, with an excessively large maximum particle size, the graphite has a smaller contact area with the molten metal, so that the sintered plug composition has a reduced corrosion resistance. The silicon nitride is used for better corrosion resistance and sintering force of the plugging composition. With an excessively large maximum particle size, the silicon nitride is reduced in specific surface area and contact area with the molten metal, resulting in a plugging composition with poor corrosion resistance. In addition, the resulting plugging composition contains the silicon nitride in a low volume ratio and therefore has a low sintering force. The mixing ratio of graphite and silicon nitride is not limited, but it is preferred that the graphite: silicon nitride weight ratio be about 25-65: 75-35, preferably about 35-55: 65-45. . (c) Refractory Clay Any refractory clay conventionally used in this technical field can be used in the present invention without limitation. Normally, a highly refractory clay comprising mainly kaolinite, halloysite and similar kaolin minerals is used. The maximum particle size of the refractory clay is not limited, but is usually about 50 μm or less, preferably about 30 μm, preferably about 20 μm or less. A refractory clay can also be used where the particles having a diameter of 1 μm or less give at least 40% ratio. The proportions of the refractory aggregate (a), the graphite and silicon nitride (b) and the refractory clay (c) in the mixture of the three components (a) to (c) (hereinafter, said mixture sometimes referred to as "refractory powder") are not limited. However, the proportion of the refractory aggregate (a) is usually from about 60 to 85 parts by weight, preferably about 70 to 83 parts by weight, per 100 parts by weight of the refractory powder; the proportion of the graphite and silicon nitride (b) is usually from about 5 to 30 parts by weight, preferably about 8 to 20 parts by weight, per 100 parts by weight of the refractory powder and the proportion of the refractory clay (c) it is usually from about 5 to 15 parts by weight, preferably about 7 to 13 parts by weight, per 100 parts by weight of the refractory powder. (d) Compatable Binder Mixture The compatibilized binder mixture for use in the present invention comprises a phenolic resin, a ketone compound and a pitch. The phenolic resin can be any of the phenolic resins, modified phenolic resins and similar resins conventionally used as binders in this technical field. Commercial products of these resins can also be used. Examples of useful phenolic resins include novolac thermosetting phenolic resins, thermosetting resole phenolic resins and benzyl ether thermosetting phenolic resins. Phenols usable as a phenolic resin material include for example, phenol and substituted phenols such as cresol and xyleneol. The aldehydes usable as the other phenolic resin material include, for example, formaldehyde, acetaldehyde, butylaldehyde and furfural. Phenolic resins can be used either alone or in combination. The ketone compound for use in the compatibilized binder mixture is not limited and may be, for example, an aliphatic ketone, an alkylaryl ketone, an aromatic ketone or a cyclic ketone. Specific examples of ketone compounds include compounds represented by the formula (1) wherein Ri and R2 may be the same or different and each represents a linear or branched substituted or unsubstituted Ci to Cs alkyl, alkenyl or Ci to C6 substituted or unsubstituted linear or branched, C3 to Cs substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylalkyl, or a similar group; or Ri and R2 can be taken together optionally to form substituted or unsubstituted C3 to C8 cycloalkyl, substituted or unsubstituted aryl or a similar group. The linear or branched Ci to C6 alkyl can be substituted, for example, by hydroxyl. The linear or branched Ci to C6 alkenyl can be substituted for example by phenyl, naphthyl or similar aryl, or hydroxyl. The aryl may be, for example, phenyl or naphthyl.

The alkyl portion of the alkylalkyl can be, for example, linear or branched Ci to C alquilo alkyl. The aryl portion of alalkyl may be, for example, phenyl or naphthyl, each of which may be substituted. Each of the cycloalkyl, C3 to C8 aryl, and aryl portion of alalkyl can be substituted, for example, by linear or branched Ci to C6 alkyl. Specific examples of ketone compounds include acetone, diethyl ketone, methyl ethyl ketone, isobutyl methyl ketone, diisobutyl ketone, acetophenone, benzophenone, dicyclopropyl ketone, diacetone alcohol, mesityl oxide, forone, sophorone, cyclohexanone, methylcyclohexanone, diphenone and camphor. Among these compounds, diacetone alcohol, mesityl oxide, forona, cyclohexanone, methylcyclohexanone, acetophenone, diphenone and camphor are preferred. These compounds can be used alone or in combination. The mixing ratio of the phenolic resin and the ketone compound in the compatibilized binder mixture is not limited, but the weight ratio of phenolic resin: ketone compound is usually about 90-20: 10-80, preferably about 80-30: 20-70. Any pitch used conventionally in this technical field can be used without limitation as the pitch for use in the compatibilized binder mixture. Examples of useful areas include coal tars (coal tar pit), oil pit and coal pit.

The proportion of the pitch in the compatibilized binder mixture is not limited, but is usually from about 0.5 to 30 parts by weight, preferably about 1 to 25 parts by weight, more preferably from about 3 to 20 parts by weight, per 100 parts by weight of the binder mixture. When the proportion of the pitch is too large, the favorable properties of the phenolic resin are imparted, such as the characteristic of fast drying and good sintering force. In addition, the resulting compatibilized binder mixture has an increased viscosity and therefore, the binder mixture needs to be added in an increasing amount, consequently it is not economical. In the plugging composition of the invention, a tar can be used as a binder, in combination with the compatibilized binder mixture. Any tar used conventionally in this technical field can be used without limitation. Examples of usable tars include coal tars (oils produced by dry coal distillation), shale tars (oils produced by dry distillation of oil shale), wood tars, gas tars (petroleum gasification byproducts) , petroleum tar (a generic name for vaporization residues or distillation of petroleum or its pyrolysates, including petroleum asphalt, distillation residue, pyrolysis tar and the like). The proportion of the tar to be added is not limited, but is usually about 20 parts by weight or less, preferably about 3 to 15 parts by weight, preferably about 5 to 10 parts by weight, relative to 10 parts by weight of the compatibilized binder mixture. The viscosity of the compatibilized binder mixture is not limited, but normally it is from about 1000 to 40000 mPa's, preferably from about 2000 to 10000 mPa's, measured at 30 ° C. If a tar is used in combination with the compatibilized binder mixture, the viscosity of the binder component consisting of the bitumen and compatibilized binder mixture is not limited, but is usually about 1000 to 40000 mPa's, preferably about 2000 to 10000 mPa's, measured at 30 ° C. The binder component for use in the invention, which consists of the compatibilized binder mixture and optionally a tar, can be prepared for example, by the following methods: first, a phenolic resin and a ketone compound are mixed together to obtain a solution . A pitch is added to the solution, optionally together with a tar followed by kneading. The kneading time is not limited as long as a homogeneous mass can be obtained, but normally it is approximately 0.5 to 2 hours. The kneading can be done with heat, to reduce the viscosity of pitch and tar. The heating temperature is not limited, but is usually about 100 ° C or less, preferably about 60 to 80 ° C. Alternatively, a ketone compound and a pitch, optionally together with a tar, may be added at the same time to a phenolic resin, followed by kneading. Alternatively, the compatibilized binder mixture can be prepared first and then mixed with a tar, followed by kneading. In these processes, the phenolic resin can be a resinified product, or they can be non-resinsified materials, i.e., a phenol and an aldehyde. The non-resinsified materials, when used, are resinified during the preparation of the compatibilized binder mixture. The proportion of the binder mixture compatibilized in the corking composition of the invention is not limited, but is usually about 15 to 25 parts by weight, preferably about 17 to 23 parts by weight, relative to 100 parts by weight of the powder refractory. The proportion of the binder component consisting of the compatibilized binder mixture and tar (the combined amount of the compatibilized binder mixture and tar) is not limited, but is usually from about 15 to 25 parts by weight, preferably about 17 to 23 parts by weight. weight, relative to 100 parts by weight of the refractory powder. (e) Organic fine fiber Any organic fine fiber can be used in the present invention, provided it has a melting point lower than the furnace wall temperature (approximately 300 ° C). The melting point of the organic fine fiber is preferably about 250 ° C or less, preferably about 100 to 200 ° C. Examples of fibers having said melting point include polyester fibers, polyvinyl alcohol fibers, acrylic fibers, polyvinyl chloride fibers, acetate fibers, rayon fibers, polyamide fibers, polyethylene fiber, polypropylene fibers, polyurethane fibers, polyvinylidene chloride fibers and other low melting organic fibers. Among these fibers, polyester fibers, polyvinyl alcohol fibers, acrylic fibers and polyvinyl chloride fibers are preferred, among which polyester fibers and polyvinyl alcohol fibers are preferred. These organic fine fibers can be used alone or in combination. Organic fine fiber is not limited in shape, as long as it has a fibrous shape. The fiber diameter of the organic fine fiber is not limited, but is usually about 5 to 200 μm, preferably about 5.5 to 100 μm, preferably about 6 to 50 μm. If the diameter of the fiber is too small, the organic fine fiber has little dispersion in the corking composition. On the other hand, if the diameter of the fiber is too large, it is likely that the expected result can not be reached. The fiber length of the organic fine fiber is not limited, but is usually about 3 to 15 mm, preferably about 4.5 to 12 mm. If the fiber length is too short, the fiber is in powder form and does not function as a fiber, whereas if the fiber length is too long, the packing composition will have a reduced lubricity.

The proportion of the organic fine fiber is not limited, but is usually from about 0.01 to 0.75 parts by weight, preferably about 0.30 to 0.7 parts by weight, preferably about 0.05 to 0.6 parts by weight, relative to 100 parts by weight of the powder refractory. If the proportion of the fiber is too small, the resulting plugging composition is insufficient in gas permeability and adhesive strength. On the other hand, if the proportion of the fiber is too large, the resulting plugging composition is exposed to be insufficient in kneading, plasticity and lubricity (extrudability) properties. In addition, the necessary amount of the compatibilized binder mixture is increased, therefore it is unfavorable from the economic point of view. The plugging composition of the present invention may also contain, when necessary, additives used conventionally in this technical field. Usable additives include curing agents and viscosity modifiers. Examples of curing agents include hexamethylenetetramine and paraformaldehyde. Examples of viscosity modifiers include ethylene glycol, diethylene glycol, propylene glycol and other glycols; and polyoxyethylenenonophenol, polyoxyethylene oleyl ether, sodium dodecylbenzenesulfonate and similar surfactants. The plugging composition of the invention can be prepared, for example, as follows: First, the particle size of the refractory aggregate (a), the graphite and silicon nitride (b) and the clay (c) is adjusted in an ordinary manner and the three components are mixed to prepare a refractory powder. An organic fine fiber is added to the refractory powder, followed by mixing until the fiber has completely dispersed. Then, the binder mixture compatibilized with mixing and heating is added, followed by kneading to homogeneity to obtain in this way, a corking composition. When a tar is used as a binder in combination with the binder mixture compatibilized, the tar can be added to the prepared packing composition, followed by kneading to homogeneity. Alternatively, the tar can be premixed with the compatibilized binder mixture to prepare a binder component, which is then added to a mixture of the refractory powder and the organic fine fiber to thereby obtain a corking composition. The plugging composition of the invention is useful for plugging blast furnace pits to produce iron ingots or the like, electric furnaces, cupola and similar apparatus for melting metal. The runner plugging composition (mud) of the invention has favorable properties of both pitch and phenolic resin used as binders. More specifically, the tamponade composition of the invention has the following remarkable properties. 1) The composition can be easily kneaded and has a high plasticity and a high density after plugging and therefore, it is easily applicable to spouts. 2) The composition has good sinterability, and therefore is able to stop the casting of molten metal immediately after being filled in the runner. 3) The composition has good gas permeability due to its high porosity and thus is unlikely to disintegrate or thicken during sintering. 4) The sintered composition shows a high permanent linear change and a high bond strength to the kiln wall, because the organic fine fiber contained in the composition is fused by the temperature of the kiln wall when the runner is filled with the composition. 5) The composition has a good resistance to corrosion after sintering and thus can prevent the molten metal from spilling over a long period. 6) The composition has a suitable sintering force and therefore the composition can prevent the molten metal from spilling, and an orifice can easily be drilled through the composition. 7) The composition does not produce smoke or dust during drilling. 8) The composition is economic.

PREFERRED MODALITY OF THE INVENTION The following examples are provided to illustrate the invention in detail and do not limit the scope of the claims of the invention.

EXAMPLES 1 TO 6 Preparation of plugging compositions (a) A refractory aggregate, (b) graphite and carbon nitride and (c) a refractory clay were subjected to particle size adjustment, and mixed together to prepare a refractory powder. To the refractory powder was added (e) an organic fine fiber, and the resulting mixture was mixed until the fine organic fiber had completely dispersed. Then, (d) a compatibilized binder mixture was added, followed by kneading. When a tar was used as a binder in combination with the compatibilized binder mixture, the tar was added to the tamponade composition prepared above from components other than tar, and the resulting composition was kneaded until homogeneous. In the above procedure, all kneading steps were carried out at 70 ° C. Table 1 shows the proportions of the components used in examples 1 to 6. The tar and pitch were coal tar and coal pitch, respectively. The compatibilized binder used was "NK-3" manufactured by Kanae Kagaku Kogyo K.K. The organic fine fiber used was a polyester fiber having a fiber diameter of 15 μm (2 deniers).

TABLE 1 NJ Notes 1) The values presented in Table 1 are proportions (parts by weight) based on 100 parts by weight of the refractory powder. 2) The value shown with the name of each refractory powder component indicates the maximum particle size or particle size scale. 3) The value shown below the term "compatibilized binder mixture" indicates the proportion "(parts by weight) of the pitch per 100 parts by weight of the binder mixture Table 2 shows the particle size distribution of the refractory powder (size maximum particle: 3.4 mm) used in Examples 1 to 6 and Comparative Examples 3 to 7 and 9 which appear below Table 3 shows the particle size distribution of the refractory clay used in Examples 1 to 6 and in the comparative examples 1 to 5 and 7 to 9 that appear later.

TABLE 2 TABLE 3 Table 4 shows characteristics of the compatibilized binder mixture (containing 5 parts by weight of a pitch per 100 parts by weight of the binder mixture) used in Examples 1 to 4 and 6 and in Comparative Examples 5 to 9 which appear more ahead.

TABLE 4 Table 5 shows the properties of kneading, plasticity, lubricity (extrudability), sinterability, contamination properties, adhesion strength and economy of the corking compositions prepared in examples 1 to 6 and comparative examples 1 to 9 which appear more ahead. Table 6 shows the permanent linear change, modulus of rupture, compressive strength, porosity and corrosion index of the corking compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 9.

TABLE 5 NJ T.

Notes: 1) The alphabetic symbols in Table 5 indicate the following: A: Good; B: Satisfactory; C: Slightly deficient; D: Poor. 2) The kneading and plasticity properties were evaluated based on the tangible characteristics of the kneaded products. 3) The lubricity (extrudability) was tested as follows: The plugging compositions were each placed in a cylindrical container (100 mm in diameter) with an end portion tapered at an angle of 45 ° to a diameter of 20 mm . Each composition was extruded from the opening (20 mm diameter) at the tapered end, at a pressure of 100 kg / cm2 to evaluate the lubricity (extrudability) based on the continuity and surface characteristics of the extruded compositions. 4) The sinterability was tested as follows: The plugging compositions were each formed in a cylinder (50 mm in diameter and 50 mm in height) and placed in an atmosphere at 600 ° C for 10 minutes. Then, the sintered compositions were taken out to measure the compressive strength. 5) The contamination properties were tested in the following manner: the plugging compositions were each formed in a cylinder (50 mm in diameter and 50 mm in height) and placed in an atmosphere at 600 ° C for 10 minutes to Evaluate the amount of smoke produced. 6) The bond strength was tested as follows: The plugging compositions were each formed in a cylinder (50 mm in diameter and 50 mm in height) and pressed on a chamotte brick heated to 800 ° C. The compositions were heated at 800 ° C for 10 minutes to allow the compositions to sinter and adhere to the bricks. Then, the bond strength to the bricks was measured.

TABLE 6 NJ or Notes: 1) The permanent linear change was measured as follows: The plugging compositions were each formed in a rectangle (40 mm x 40 mm x 160 mm) and molded under pressure at a pressure of 100 kg / cm2. After pressure molding, the length that had initially been 160 mm was measured as. The pressure molded compositions were sintered in a reducing atmosphere at 1450 ° C for 3 hours. After sintering, the length that had initially been 160 mm was measured as l2. The permanent linear change is the speed of change in length, calculated according to the following equation: Permanent linear change (%) = (l2-l?) /) X 100. 2) The modulus of rupture and resistance to compression were measured in accordance with JIS R2553. 3) The corrosion index was determined as follows: the plugging compositions were formed and placed in a high frequency test melting furnace. Then, iron and slag were melted at 1500 ° C in the test melting furnace. The amount of corrosion of each composition was measured to find an index of corrosion. The lower the corrosion rate, the better the resistance to corrosion. The plugging compositions of Examples 1 to 6, after sintering, showed a sufficient sintering force to stop the casting, and a hole was easily made through the sintered compositions.

The plugging compositions of Examples 1 to 3 and 6 vary in amount of the added organic fine fiber. Table 6 reveals that these compositions are good in kneading properties, plasticity and lubricity (extrudability), and therefore are easily applicable to spouts. In addition, Table 7 shows that the permanent linear change values of these compositions were positive, and that these compositions were excellent in physical properties such as corrosion resistance. Likewise, they present good sinterability, high adhesion strength and other excellent properties such as plug-in plugging compositions., in comparison with the compositions of the comparative examples that appear later. The plugging composition of Example 4 contains both a binder mixture compatibilized according to the invention and a tar conventionally used as a binder. The composition of Example 4 can be prepared with improved economy, without impairing the favorable properties of the compatibilized binder mixture. The plugging composition of Example 5 contains a compatibilized binder mixture containing 10 parts by weight of a pitch as dissolved in 100 parts by weight of the binder mixture. As for the composition of Example 5, the amount of the binder mixture compatibilized which is to be added is slightly increased because the binder mixture has a slightly high viscosity. However, the composition has an acceptable economy and excellent properties.

COMPARATIVE EXAMPLES 1 AND 2 The plugging compositions were prepared following the procedure of Example 1 except that a refractory aggregate having a maximum particle size of 6 mm or less was used, and that a tar or phenolic resin was used as a binder in place. of the compatibilized binder mixture, and that the organic fine fiber was not used. Table 1 shows the proportions of the components used. The compositions of Comparative Examples 1 and 2 are deficient in plasticity, lubricity (extrudability) and other properties, due to the excessively large particle size of the refractory aggregate (alumina or bauxite). The composition of comparative example 1, although economic, is markedly inferior to the compositions of the examples in sinterability and non-contamination properties. The composition of comparative example 2 is satisfactory in sinterability and non-contamination properties, but lower in adhesion strength and economy to the compositions of the examples.

COMPARATIVE EXAMPLE 3 A plugging composition was prepared following the procedure of Example 1 except that a phenolic resin was used in place of the compatibilized binder mixture. Table 1 shows the proportions of the components used. The plugging composition of Comparative Example 3 is insufficient in kneading properties, plasticity, lubricity (extrudability), adhesive strength and other properties, as compared to the compositions of the examples. Furthermore, this composition is not economical since it contains a large amount of the phenolic resin as a binder.

EXAMPLE COM PARATIVE 4 A plugging composition was prepared following the procedure of Example 1 except that a phenolic resin was used in place of the compatibilized binder mixture, and that the organic fine fiber was not used. Table 1 shows the proportions of the components used. The composition of Example 4 is not economical and is insufficient in plasticity, lubricity (extrudability), corrosion resistance and other properties, as compared to the compositions of the examples. Also, it takes much longer to make a hole through this composition, than through the compositions of the examples.

COMPARATIVE EXAMPLE 5 A plugging composition was prepared following the procedure of Example 1 except that the organic fine fiber was not used. The composition of comparative example 5 is insufficient in plasticity, lubricity (extrudability) and corrosion resistance, in comparison with the compositions of the examples. In addition, due to its negative permanent linear change value, this composition is inferior to the compositions of the examples in adhesion strength to the furnace wall.

COMPARATIVE EXAMPLE 6 The procedure of Example 1 was followed except that the refractory clay was not used, in order to prepare a tamponade composition. However, the resulting composition was difficult to knead and showed poor plasticity, therefore it could not be formed. Consequently, it was impossible to test the sinterability, adhesion and other properties of the composition.

COMPARATIVE EXAMPLE 7 A plugging composition was prepared following the procedure of Example 1 except that the silicon nitride was not used. The composition of Comparative Example 7 is inferior in sinterability, and in particular, markedly inferior in corrosion resistance to the compositions of the examples.

COMPARATIVE EXAMPLE 8 The procedure of Example 1 was followed except that alumina with a scale of particle size of 5 to 8 mm and graphite with a particle size scale of 1 to 3 mm was used, in order to prepare a plugging composition. However, the resulting composition was difficult to knead and showed poor plasticity, therefore it could not be formed. Consequently, it was impossible to test the sinterability, adhesion and other properties of the composition.

COMPARATIVE EXAMPLE 9 A plugging composition was prepared following the procedure of Example 1 except that a metal fiber (a cast iron fiber having a fiber diameter of 90 μm) was used in place of the organic fine fiber. The composition of Comparative Example 9 is inferior in sinterability and corrosion resistance to the compositions of the examples.

COMPARATIVE EXAMPLE 10 An attempt was made to prepare a binder mixture consisting only of a phenolic resin (9 parts by weight) and a pitch (one part by weight). However, the phenolic resin and pitch were incompatible with each other and did not form a homogeneous mixture. Therefore, it was impossible to prepare a plugging composition using a binder mixture consisting only of the phenolic resin and pitch.

Claims (6)

NOVELTY OF THE INVENTION CLAIMS

1. - A runner plugging composition for metal melting apparatus, comprising (a) a refractory aggregate having a maximum particle size of 5 mm or less, (b) graphite and silicon nitride, each having a particle size maximum 0.2 mm or less, (c) a refractory clay, (d) a compatibilized binder mixture comprising a phenolic resin, a ketone compound and a pitch, and (e) an organic fine fiber.

2. The runner plugging composition according to claim 1, further characterized by the refractory aggregate (a) is at least one element selected from the group consisting of alumina, high alumina, silicon carbide, bauxite, mullite, chamotte, pyrophyllite, coke, zirconia, ferrosilicon and magnesia.

3. The runner plugging composition according to claim 1, further characterized in that the compatibilized binder mixture (d) has a pitch content of 0.5 to 30 parts by weight per 100 parts by weight of the binder mixture.

4. The runner plugging composition according to claim 1, further characterized in that the organic fine fiber (e) is at least one element selected from the group consisting of polyester fibers, polyvinyl alcohol fibers, acrylic fibers, polyvinyl chloride fibers, acetate fibers, rayon fibers, polyamide fibers, polyethylene fibers, polypropylene fibers, polyurethane fibers and polyvinylidene chloride fibers.

5. The runner plugging composition according to claim 1, further characterized in that the organic fine fiber (e) has a fiber diameter of 5 to 200 μm and a fiber length of 3 to 15 mm.

6. The corking composition according to claim 1, which comprises 100 parts by weight of a refractory powder consisting of 60 to 85 parts by weight of the refractory aggregate (a), 5 to 30 parts by weight of the graphite and silicon nitride (b) and 5 to 15 parts by weight of the refractory clay (c); 15 to 25 parts by weight of the compatibilized binder mixture (d) relative to 100 parts by weight of the refractory powder; and 0.01 to 0.75 parts by weight of the organic fine fiber (e) relative to 100 parts by weight of the refractory powder.