MXPA98007274A - Refractory composition for producing compact castable and wet spraying method - Google Patents

Abstract

A refractory composition for producing a compact castable, comprising a main material free from cement, containing 70 to 98 wt.%refractory aggregate of less than 10 mm in grain size and 2 to 30 wt.%refractory ultra-fine powder of less than 10&mgr;m in grain size;and a dispersant equivalent in quantity to 0.01-1.0 wt.%of the main material. The composition kneaded with water or other liquid to a desired softness, or in the form of a premix, is forcedly sent to a spray nozzle by a pressure-feed pump, and sprayed together with a coagulant by compressed air.

Description

MOLDING REFRACTORY COMPOSITION TO PRODUCE DIFFERENT EMPTY REFRACTORS, AND ALL MACHINES APPLIED WITH GUN IN HVMEPP. PE UOS MSMOS FIELD PE INVENTION The present invention relates to a castable refractory composition for producing dense, refractory refractories usable as coatings for containers for molten metals such as cauldrons, »coppers,» etc. »and a method for applying it with wet gun. Refractory materials for casing coatings for molten metals have been changing lately from bricks to easy to apply molding products as cast refractories have been provided with more and more improved durability. However, the emptying methods are still disadvantageous in terms of time and labor required to place the forms in the emptying. On the other hand, "spray-applied coating methods contribute to reducing labor and time consumption" and have versatility of repair "because these methods do not require the placement of forms and allow quick repairs to be made quickly. As a result »spray coating methods have been finding more and more applications. Although more widely used now is a method of dry-applied coating »it produces refractory coats with little durability and produces bounces and dusts» which results in a poor working environment. To overcome the problems of dry-spray coating methods, "recently, advances have been made to provide various spray-applied coating methods" such as a semi-dry spray-applied coating method »an applied coating method with wet gun »etc.» and refractory materials for them. In the semi-dry gun coating method, the gun-applied coating refractory material is premixed with a necessary part of water by means of a mixer. It is pneumatically conveyed to a coating nozzle applied by a med. Gun to a coating machine. applied with a dry gun "is mixed with the remaining water" or with a solution or a suspension containing hardening agent in the mouth of the applied coating with a spray gun (or before reaching the spray nozzle) "and then It is applied with a spray gun through the nozzle. Semi-dry spray coating methods are exemplified in Japanese Patent Laid-Open No. 61-111973 and Japanese Patent Publication Nos. 2-27308 »6-17273, 5-63437 and 5-21B66. etc. Japanese Patent Laid-Open No. 61-111973 discloses the combination of a hardening accelerator and sodium silicate as a binder "and Japanese Patent Publication Nos. 2-27308 and 6-17273 discloses low-moldable products. of cement as coating materials applied with a gun. Similarly, Japanese patent publications Nos. 5-63437 and 5-21866, "recognized by the same applicant", describe moldable refractory materials containing ultra-fine powders and dispersing agents, which do not harden at room temperature. Specifically »in the first reference» a refractory clay is used as an inductible component and hardened by Ca (0H), »and sodium silicate or sodium aluminate introduced in a nozzle to improve the resistance to dry explosive cracking. In the latter reference »a refractory composition to which a moisture retention agent is added is premixed with water in an amount of 1 / 5-3 / 4 of the amount normally required in a factory to provide a wet mix» which is then hardened by sodium silicate »sodium aluminate or colloidal silica introduced into a nozzle. Although improvements were achieved to some degree in these spray-applied coating methods to reduce dust generation and bounce losses, these spray-applied coating methods still produce refractory coats with adhesion "poor homogeneity and density" as the materials refractories should be mixed instantly with water or an aqueous solution in a nozzle »resulting in poor mixing at an unstable water ratio. On the other hand, the wet-applied coating method is a method in which the spray-applied coating refractories are pre-mixed with all the water that is required for the spray-applied coating "or a method in which the refractories of type Premixed assortments in premixed form are coated by spray application. In wet spray coating methods, it is possible to add a small amount of an aqueous solution of a curing agent or a hardening adjustment agent to the refractory coating applied with a gun in a nozzle. Wet-spray coating methods are classified into a pneumatic transport method by a spray-applied coating machine and a pump transport method, depending on how spray-applied coating materials are transported. In the case of the pumping method »compressed air is introduced into the nozzle to spray refractory materials. The present invention belongs to the latter category. Depending on the amount of water added »spray-applied coating materials are provided with various manageabilities ranging from a plastic level to a suspension level. These methods of wet-applied coating are exemplified in the Japanese patent publication NOS. 57-7350 »62-21753. 2-33665 »2-1795. etc. Because the spray-applied revetment materials described in Japanese Patent Publication No. 57-7350 are in the form of a suspension having a water content of 10 to 20%, they are not expected to be layered. dense refractories suitable for coatings of containers for molten metals. In the last 3 methods »the refractory materials applied by spray guns are supplied in the form of a wet premix with water or a solution» making it possible for them to be produced and stored in factories »as in the present invention. These methods of wet-applied coating contribute to reduce labor and improve the work environment "because no tempering is required at the spray applied coating site. However, these conventional methods do not use the dispersion action of the ultrafine refractory powder to reduce the amount of water added. They are also not yet different in composition from the refractory materials of previous generations, for example, due to the maximum size of 4 mm or less in the particles contained in the spray-applied coating materials. In addition »they use spray coating machines as means to transport the refractories. Therefore »the refractory layers applied with a gun are of insufficient strength, and thus of considerably poor durability. comparatively with those produced from moldable refractory materials »particularly dense moldable products. Accordingly, it is an object of the present invention to provide a castable refractory composition capable of producing dense cast refractories having high density, strength and corrosion resistance at a low water content, and a method of gun applying said moldable refractory composition. . When ultrafine refractory powder is dispersed in water, there are two types of force: an attractive force and a repulsive force. working between the suspended particles, and a synthetic force of these two forces is applied to the particles. The force of attraction is a van der Waals force "and the repulsion force is an electrostatic force between the electric double layers on the surface of the particles. When the repulsion force exceeds the attractive force by action of the dispersing agent, the suspended particles are kept in a dispersed state. In this state, the water retained between the agglomerated particles is kept free as free water which contributes to increase the fluidity, making the refractory materials flowing at a low water content. When an electrolyte (coagulant) ion-releasing such as H *. Mg * "* -. Ca * - * - Al» *. SO ^ * - »C03a- is added to a concentration greater than a certain level in this state» the repulsion force decreases, so that the force of attraction arrives to be relatively greater than the repulsion force, resulting in the rapid coagulation of the ultrafine refractory powder What this mechanism uses are so-called dense moldable refractory materials, such as ultra low-cement mouldable products »low-mouldable products of cement »etc .. Particularly in ultra low cement content molding products containing 3% by weight or less of aluminum oxide cement» it can be considered that aluminum oxide cement works as a coagulant. It is in fact impossible to achieve good manageability at a low water content simply by adding the dispersing agent and the coagulant to the refractory material, because both are additive. In opposite properties they act simultaneously. However, actual refractory materials are usually provided as products containing dispersing agent and coagulant. Therefore, the refractory material must have said composition in order to have a mechanism that in a case where the refractory material tempered with a small amount of water is drained while there is good manageability by the action of the dispersing agent, the setting occurs by action of the coagulant deßpuéß of a certain period. There have been known methods for that purpose: (i) a method that uses as a coagulant a material such as aluminum oxide cement, slowly dissolving the ions in water »and adding a setting retarder to suppress ion release» and (ii) ) a method that uses a coagulant that has a high rate of dissolution, the coagulant being precoated with materials such as gelatin, casein, gum arabic, etc. to retard coagulation. However, it is very difficult to adjust the working time (period in which the fluidity is maintained) and the setting time (time at which the setting ends) within a predetermined scale, depending on the variations in ambient temperature, the temperature of the article on which the applied coating with wet gun applies »and the work environment, which is a major problem to be overcome.

BRIEF DESCRIPTION PE I? INVENTION To cope with the problems accompanied by the mechanism by which the coagulant functions after the lapse of time in the wet-applied coating method, it is necessary for the coagulant to exhibit its function immediately after it is introduced into the nozzle. Namely, it is a primary condition that the coagulant exhibits nastically a sufficient coagulation effect to adhere a refractory material applied with a gun to a surface "while retaining its shape (without slump). As a result of various investigations, the inventors have found that the foregoing problems can be overcome in the wet-applied coating method by tempering a refractory composition comprising ultrafine refractory powder and a dispersing agent with water in order to have moldable fluidity »by transporting the warm mixture to a spray nozzle applied by a pump» adding a coagulant to this mixture together with compressed air in the nozzle »and applying the resulting mixture with a spray gun through the applied spray nozzle . The present invention is based on this discovery. The cement-free castable refractory composition for producing dense refractory refractories according to the present invention comprises from 70 to 9854 by weight of refractory aggregate material regulated to have a particle size of 10 mm or less of from 2 to 30% by weight. refractory powder of ultrafine powder having a particle size of 10 μm or less »and from 0.01 to 1.05 μ in weight (percentage on the outside), with baßee at 100 ° in the aggregate refractory material plus the ultrafine refractory powder de of a Diffusion agent. In accordance with the present invention. the castable refractory composition of the premixed type comprises a mixture of the above cement-free castable refractory composition and a thickener, the mixture being pre-mixed with anteroan with water or other hardening liquids in said amount to provide the mixture with a moldable fluidity. The method for coating by gun application a moldable refractory composition in accordance with the present invention comprises the steps of transporting the above molded refractory castable composition with water or other hardening liquids in order to have a castable or flowable refractory composition. moldable »to a coating nozzle sprayed by a pump» add a coagulant to the warm mixture together with compressed air in the spray nozzle applied with a spray gun; and spray the resulting mixture through the spray nozzle applied with a gun.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph showing the relationship between the amount of an added coagulant aqueous solution and the coagulabi lity in a case where aqueous solutions of various coagulants are added to the ultrafine refractory powder (calcined aluminum oxide), and Figure 2 is a graph showing the relationship between the amount of an added coagulant aqueous solution and the coagulabi lity in a case where an aqueous solution of a coagulant (calcium chloride) was added to various types of ultrafine refractory powder.

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be explained in detail.

The moldable refractory composition The moldable refractory composition of the present invention for wet-applied coating comprises: (A) refractory aggregate material »(B) ultrafine refractory powder and (or a dispersing agent.

(A) Refractory aggregate material The aggregate refractory material that can be used in the present invention may be at least one of the group selected from the group consisting of electrofused aluminum oxide. concreted aluminum oxide »bauxite, kyanite» andalusi ta. mulita, chamotte. pyrophyllite »silica, aluminum oxide-magnesium oxide spinel» magnesium oxide, zirconia »zirconia» silicon carbide »graphite» pitch »etc. and doß or máß of the loe ße can be combined» if necessary. The particle size of the refractory aggregate material eß of 10 mm or less. When the particle size of the refractory aggregate material is more than 10 mm, the pumping efficiency is reduced, increasing the rebound loss. The amount of the refractory aggregate material is 70 to 98X by weight based on 1005% by weight of the refractory composition. The preferred amount of refractory aggregate material is 75 to 95% by weight.

(B) Ultrafine refractory powder The ultrafine refractory powder that can be used in the present invention can be at least one selected from the group consisting of ultrafine powder of aluminum oxide »amorphous silica, silica, titanium oxide, mulita, zirconia . Chromium oxide, silicon carbide »carbon» etc. »and two or more of the loe can be combined, if necessary. The particle size of the ultrafine refractory powder is 10 μm or less, preferably 1 μm or less. When the particle size of the ultrafine refractory powder eß of more than 10 μ, the reducing effect of water is reduced in combination with the dispersing agent. When the particle size of the ultrafine refractory powder is 1 μm or less, the water reducing effect is remarkable. The amount of the ultrafine refractory powder is from 2 to 30% by weight. When the amount of the ultrafine refractory powder is less than 2% by weight, the reducing effect of the water is less. When the amount of ultrafine refractory powder is greater than 30? by weight, a greater amount of water is required to apply the coating with a gun, causing the resulting refractory layers to suffer from a large contraction after combustion. The preferred amount of the ultrafine refractory powder is from 5 to 25% by weight.

(C) Dispersing agent The dispersing agents that can be used in the present invention can be one or more selected from alkali metal ßaleß of condensed β-phosphoric acid. such as sodium hexametaphosphate, etc. or alkali metal salts of silicic acids; organic acids such as β-carboxylic acid, humic acid, sulfuric acid, sulfonic acid, etc., or alkali metal salts thereof. The amount of the dispersing agent is from O.O.sub.L to 1% by weight (percentage on the outside) with ba.se in 100% by weight of the refractory aggregate material plus the ultrafine refractory powder. When the amount of the dispersing agent is less than O.Oi? by weight, sufficient expulsion effects are not obtained. When it is greater than 1% by weight, an optimum dispersion is not achieved. The preferred amount of the dispersing agent is 0.03 to 0.8% by weight.

C2-I Moldable Refractory Compounds of Premixed Type The molded refractory composition of the ready-mixed type comprises a thickener and water or other hardening liquids in addition to the refractory aggregate material »ultrafine refractory powder and dispersing agent above.

(D) Thickener The thickener acts to prevent the segregation of particles of the ingredient and the separation of a liquid fae in the course of transportation of the preblended moldable refractory composition to a spray-applied revetment site. In addition, it is expected to act as a coaglutinant. The thickeners used in the present invention are not restricted as long as they can be used as food additives, additives for civil engineering or for construction, etc. Particularly preferable among others are organic compounds of cellulose and / or copolymers of isobutyl leno-anhydride. maleic The amount of the added thickener is preferably 0.01 to 1% by weight (percentage on the outside) with 100% by weight of the refractory aggregate material plus the ultra-fine refractory powder. When the amount of the thickener is less than 0.01% by weight, the effects of thickening are too small to avoid segregation of the particle from the ingredient and the separation of the liquid components. On the other hand, when it is greater than 1% in peel, problems such as decrease in flowability and resistance to dry explosive cracking occur. The preferred amount of the thickener is from 0.02 to 0.8% by weight.

C3D Other components Both the castable refractory composition and the above-mentioned castable refractory composition can further contain, as other components such as inorganic or metal fibers, agents to avoid explosive cracking in dry conditions, such as metallic alumino-oxycarbons, organic fibers »etc ..

C43 Spray applied method with gun The moldable refractory composition containing the above constituents is quenched with water or other hardening liquids to have a moldable fluidity. Although the amount of water or other hardening liquids added can vary widely »depending on the particle size distribution of the refractory materials, the porosity of the refractory aggregate material, etc., is about 5 to 8% in weight. When the amount of water or other hardening liquids added is less than 5% by weight, the fluidity is ineffective. On the other hand, when the amount of water or other liquids hardened added is greater than 8% by weight, it may occur that the applied refractory composition is sluiced. The above tempered mixture or the castable refractory composition of the premixed type is transported to a coating nozzle applied by means of a pump and applied by means of a nozzle in which a coagulant and compressed air are injected.

(E) Coagulant The coagulant is preferably an electrolyte releasing ions such as H * »OH-» or divalent or trivalent cations or anions (of opposite surface charge) such as Mg ** »Ba **, Ca **, Al **, SO ^ * -, C0a * -, etc. The models of the coagulation mechanism of the present invention appear to be isoelectric coagulation (charge neutralizing coagulation) and Schultz-Hardy coagulation. Specifically speaking, "the hydrogen ion or hydroxide ion is a potential determinant ion in most metal oxides" and isoelectric coagulation occurs by adding a small amount of the potential determining ion to eliminate the repulsive force of the electric double layer. On the other hand »the coagulation caused by an electrolyte that does not have any influence» such as adsorption on the particles perse »but rather increases the ionic intensity of a means to compress the electric double layer of particles» thus making the repulsion force Electric particles are lower that the coagulation force "is called Schultz-Hardy coagulation" or simply coagulation. The coagulates obtained by the coagulation of Schul tz-Hardy are relatively dense. The electrolyte is preferably added in the form of a solution. The coagulant solution (electrolyte) is preferably supplied by a fixed displacement pump psychomically operable with a pump for transporting the hardenable moldable refractory composition. The amount of the coagulant is cniently 0.1% to 1.5% by weight (percentage on the outside) based on 100% by weight of the refractory aggregate material plus the ultrafine refractory powder, although it may depend on the concentration of its solution. When the amount of the coagulant is less than 0.1% by weight, a sufficient coagulation effect can not be achieved. On the other hand, when the amount of the coagulant is greater than 1.5% by weight, the resulting products applied by gun have reduced density (lower overall density). The preferred amount of the coagulant is from 0.2 to 1.3% by weight. The present invention will be explained more specifically by the following examples, without the intention of limiting the same.

REFERENCE EXAMPLE 1 A calcined aluminum oxide A 2 having an average particle size of 4 μm was used as an ultrafine refractory powder, and 100 g of the aluminum oxide A calcined with 1.5 g of a dispersing agent (sodium hexametaphosphate) was mixed in a vessel. When water was slowly added to the resulting mixture, the mixture showed good fluidity at a water content of 24 g. Each of the following aqueous coagulant solutions at a concentration of 2.7 moles / liter was added to the resulting suspension, and stirred rapidly to examine the coagulabi lity of the suspension.

Coagulant specificity CaCl ,. 1.21 MgCla 1.17 SO, »1.31 AlCla 1.25 It was compared how rapidly each coagulant exhibited its coagulation effect on calcined aluminum oxide Ap. The coagulabi lity of the suspension was classified into three categories, in which category 1 represents maintenance of good fluidity, category 2 represents instantaneous disappearance of fluidity, and category 3 represents hardening in two to three seconds. The results are shown in Figure 1. As is clear from Figure 1, either of these coagulants instantly coagulated the suspension in small amounts.

EXAMPLE PE REFERENCE 2 An aqueous solution of calcium chloride at a concentration of 2.7 moles / liter was used as a coagulant solution to examine the coagulation properties of various types of ultrafine refractory powder. Ultrafinox calcined aluminum oxide (average particle size: 4 μm) was used as refractory powders »Calcined aluminum oxide Aa (average particle size: 0.7 μm)» kaolin clay (average particle size: 3 μm) and spinel (MgO * Al2Oa) (average particle size: 3.3 μm). The amount of water required to obtain the fluidity of the suspension varied, depending on the types of ultrafine refractory powders used. The amounts of water required for 100 g of the refractory powder ß ultrafinoß anterioreß and 1.5 g of sodium hexametaphosphate were 24 g. 25.5 g, 35 g and 23 g, respectively. The results are shown in Figure 2. As is clear from Figure 2, coagulation occurred more rapidly in the order of aluminum oxide A > aluminum oxide Aa > spinel > Arc.

EXAMPLES 1-4 AND COMPARATIVE EXAMPLES 1-4 1. Formulations Laß formulations of ref actariaß compositions are shown in Table 1. Ala03-SiC-C refractory compositions were used in Examples 1, 2 and 4 and Comparative Example 1-3, and they used refractory AlaOa-MgO compositions in Example 3 and Comparative Example 4. In Example 4 a pre-blended castable refractory composition was used which was premixed to a tempering water content of 6.1% by weight in the factory. 2. Spray applied by gun Those obtained by adding a quantity of water for premixing to the moldable refractory compositions and tempering them in Examples 1-3 and Comparative Example "1, or the castable refractory composition of the premixed type in Example 4, were transported to a coating nozzle sprayed by a pump The coating applied with a spray gun was carried out after a coagulant solution in an amount (percentage on the outside) shown in table 1, and compressed air »were added to the spray nozzle. coating applied with a gun in Examples 1-4 'or without adding the coagulant solution in comparative example 1. The castable refractory composition having the formulation shown in Table 1 was emptied in comparative example 2. Moldable refractory compositions having the formulations moßtradaß in table 1, laß cualeß were premixed with a pe A quantity of water was pneumatically transported to a nozzle by means of a coating machine applied with pißtola in comparative examples 3 and 4. An aqueous solution of sodium aluminate was added as a setting agent in the nozzle in comparative example 3., while only water was added to the nozzle to carry out a spray-applied coating on semi-dry in Comparative Example 4. After spray coating, each spray-applied layer was cut to a predetermined size, and dried to provide test piece. The amount of water added in the complete spray-applied coating process is shown in Table 1. In Comparative Example 2, the castable refractory composition was quenched with an amount of water for pre-mixing, cast in a mold and aged and dried in a mold. the mold to prepare test pieces. In comparative example 1, the coating applied with a gun could not be carried out, and did not allow or produce test pieces. The methods used in the examples and comparative examples are also shown in Table 1.TABLE 1 FPRPMUCIQn and training wifaoflQ Example No, 2 Refractory Aggregate Electro-cast aluminum oxide (8-5 mm) ** »17 17 17 Electro-cast aluminum oxide (5-1 mm) ** > 35 35 45 35 Electro-cast aluminum oxide (3-1 mm) ** »Electro-cast aluminum oxide (= 1 mm) *" 4 »16 16 25 16 Magnesium oxide clinker * "» 10 Silicon carbide * "» 18 18 18 Brea * -7 »2 2 TABLE 1 (CONTINUED) Ultra-fine refractory powder Ultra-fine aluminum oxide powder * "» 8 8 19 8 Amorphous silica * "» 3 3 1 3 Carbon black ** 0 »1 1 _ 1 Clay*"" Component of cement Cement of aluminum oxide ** - * » D ßpersection agent Hexametaphos ato ßodio ** "» 0.1 0.1 0.1 0.1 Eßpeßante CMC ** - »» 0.02 Copolymer of IB-MA ** "» 0.02 Agent to prevent dry explosive cracking ** "» Organic fibers 0.05 0.05 0.05 0.05 Coagulant ** "» Aqueous solution of CaCl2 0.5 0.5 Aqueous solution of MgSO. * 0.6 Aqueous solution of A1C1- 0.7 TABLE 1 (CONTINUED) Setting agent Aqueous sodium aluminate solution *** »- - - - Quantity of pre-mixed water **" »5.2 5.2 5.5 6.1 Total amount of water in the coating layer applied with a gun ** "» 5.6 5.6 6.0 6.6 Note - PM ** "» "» Training method Present invention Note: (1) Particle size: more than 5 mm and 8 mm or less, unit:% by weight. (2) Particle size: more than 1 mm and 5 mm or less, unit:% by weight. (3) Particle size: more than 1 mm and 3 mm or less »unit:% in weight. (4) Particle size: 1 mm or less, unit:% by weight. (5) Particle size: 1 mm or less »unit:% in weight. (6) Particle size: 150 μm or less, unit:% by weight. (7) Particle size: 1 mm or less, unit:% by weight. (8) Particle size: 10 μm or less, unit:% by weight. (9) Particle size: 1 μm or less, unit:% by weight. (10) Particle size: 1 μm or less, unit:% by weight. (11) Unit:% in pet. (12) JIS Class 1, unit:% by weight. (13) Concentration: 2.7 moles / liter, unit:% by weight (percentage on the outside). (14) Carboxymethyl cellulose »unit:% by weight (percentage on the outside). (15) Isobutylidene-maleic anhydride copolymer »unit:% by weight (percentage outside). (16) Concentration: 30%, unit:% by weight (percentage abroad). (17) Premixed type.

TABLE 1 (CONTINUED) Formulation and training method Comparative example No.

Refractory aggregate material Electro-cast aluminum oxide (8-5 mm) ** »17 17 Electro-cast aluminum oxide (5-1 m) **» 35 35 Electro-cast aluminum oxide (3-1 mm) * "> 40 45 PICTURE 1 (CONTINUED Electro-cast aluminum oxide (= l m) *** »16 16 26 25 Magneßium oxide clinker * "» 10 Carbide ßilicio * "» 18 18 18 Brea * - * »2 2 2 Ultra-fine refractory powder Ultra-fine aluminum oxide powder * "* 8 8 7 12 Amorphous silica * "» 3 3 3 1 Carbon black ** 0 »1 1 1 Clay ***» 3 Component of cement Cement of aluminum oxide *** » Sodium Hexametaphosphate Dispersing Agent *** »0.1 0.1 0.1 CMC Thickener «* - > »0.03 Copolymer of IB-MA **" » Agent to prevent dry explosive cracking *** »Organic fibers 0.05 0.05 0.05 0.05 TABLE 1 (CONTINUED) Coagulant ** "» Aqueous solution of CaCl, Aqueous solution of MgSO, Aqueous solution of A1C1.

Setting agent Aqueous solution of sodium aluminate ** "» 6.0 Amount of premixed water ** "» 5.2 5.2 3.0 3.0 Total amount of water in the applied coating layer with pißtola ** "» 5.2 7.2 12.3 Note Method of formation Coating Application applied with splash applied in wet with pißtola in -Vaciado- 3. Evaluation (1) Evaluation of the test pieces After measuring the overall specific gravity of each test piece calcined at 1 000 ° C and 1,500 ° C, the flexural strength and the corrosion index were measured under the following conditions. The test results are shown in table 2. (i) Flexural strength (kgf / cm *) Each test piece was measured with respect to the flexural strength after calcination (1.00O ° C and 1'500 ° C) and the flexural strength in hot (1 »500 ° C) in accordance with JIS R2553. (ii) Rotating corrosion test In group A (examples 1. 2 and 4 and exampleβ comparativeß 2 and 3). A rotating corrosion test was carried out at 1 500 ° C for 5 hours, using blast furnace slag as a corrosive material. In group B (example 3 and comparative example 4) »the rotary corrosion test was carried out at 1650 ° C for 5 hours using slag from the converter (molar ratio of (CaO / SiO ^: 4.2) as a corrosive material. Corroded test pieces were collected to measure the corrosion intensity The corrosion intensity divided by time (hours) was expressed as the corrosion index (relative value), assuming that the value of Example 1 in group A was 100 » and that the value of example 3 in group B was 100. The larger the corro- sion index, the more corroded the work piece.

TABLE Z Characteristics of the application, applied with piatola and quality of the workpieces applied with istola Non-Characteristic Example of -Buenas- -Without slump reverement applied with pißtola global specific gravity at 1,000 ° C 2.85 2.86 3.03 2.84 at 1 »500 ° C 2.85 2.85 3.00 2.85 Resistance to bending deßpuéß combußtión ** »a 1» 000 ° C 49 51 61 45 a 1,500 ° C 68 77 153 63 Hot bending fastness ** »at 1,500 ° C 28 31 21 25 Corrosion test rotating corrosion rate 100 98 100 103 Note: (i) Unit: kgf / cm *.

TABLE 2 (CONTINUED) Characteristics of the applied coating with istola v quality of the workpieces applied with istola Comparative Example Non-Characteristic of the Could not -Many applied coating applied to recontaminated Pesticide with can and powder-gun by slump global specific gravity at 1 »000 ° C 2.89 2.57 2.41 to 1,500 ° C 2.88 2.60 2.37 Resistance to flexion after combustion ** »at 1» 000 ° C - 55 39 32 a 1 »500 ° C - 81 49 38 Resistance to hot bending ** »to 1» 500 ° C - 32 15 12 Corrosion corrosion test corrosion rate - 93 153 303 Note: (1) Same as above.

As is clear from Table 2, the refractory materials in Examples 1 to 4 were well-developed by application with pipetto to form refractory products without slump, whereas the coating applied with pißtola was not well conducted due to the slump in the comparative example. 1 due to the fact that no coagulant was added to the nozzle in the coating process applied with wet paint. The revetment applied with pißtola in semi-dry in the comparative example β 3-4 showed a lot of dust and rebound loss. With regard to the quality of spray-applied refractory products, the overall specific gravity is closely related to the denseness of spray-applied refractory products. The wet-applied refractory products of Examples 1-4 have a much greater overall specific gravity than that of the refractory coating product applied with semi-dry paint, and an overall specific gravity slightly lower than that of the refractory product. emptying of comparative example 2. There is the same tendency in the corrosion index determined by the rotary corrosion test than in the overall specific gravity. The wet-applied refractory products of the examples 1-4 show corrosion resistance comparable to that of comparative example 2, while that of comparative examples 3 and 4 is very poor.

APPLICATION PE THE INVENTION IN THE INDUSTRY Refractory products applied with a gun that have quality and corrosion resistance that are much better than those of conventional refractory products applied with a gun "and comparable to those of emptied refractory products" can be obtained by supplying a refractory composition cement-free mouldable containing 10 μm or less ultrafine refractory powder and a dispersing agent which is premixed with water by means of a mixer to have moldable fluidity, or a castable refractory composition free of cement and premixed type, to a nozzle of coating applied with a gun by means of a pump; by adding a small amount of a coagulant solution (electrolyte) to it together with compressed air in the nozzle »and then applying with the spatula the residual mixture. Since the castable refractory composition of the present invention is not hardened without adding a coagulant and does not need to be hardened, it is free from the problems that the working time and hardening time must be controlled. Consequently, the premixed or tempered refractory composition does not harden in a hose or tube during the course of its transport to a nozzle by means of a pump, avoiding problems such as plugging of the hose or tube. With respect to the supply of the refractory composition, it is possible to pre-temper the castable refractory composition with water or other hardener liquids to provide it in the form of a premixed type. Furthermore, the present invention has the following advantages: (1) Spray-applied coating products have good densities and properties »compared to those of the cast products. (2) The labor force can be drastically reduced due to the annoying work of building forms »since emptying methods are not required. (3) Refractory materials can be stably inflated to a nozzle by pumping, making it possible to add a coagulant solution to a constant amount without requiring strict manual control. A ßaber »the control of water supply can be carried out without being affected by the skill and experience of the person handling the nozzle» in a different way than in the case of the coating applied with a spray gun in semi-ßeco or dry conventional. (4) Because the refractory materials are supplied in a completely flowing state, "no generates dust with extremely small rebound loss" unlike as in the case of conventional spray applied coating methods.

Claims (5)

NOVELTY PE THE INVENTION CLAIMS

1. - A cement-free moldable refractory composition »characterized in that it comprises from 70 to 98% by weight of refractory aggregate material regulated to have a particle size of 10 mm or less» 2 to 30% by weight of ultrafine refractory powder having a size particle size of 10 μm or less »and from 0.01 to 1.0% by weight (percentage on the outside) based on 100% by weight of said refractory aggregate plus said ultrafine refractory powder» of a di-phosphide agent.

2. A moldable refractory composition of the ready-mixed type, characterized in that it comprises a mixture of said moldable refractory composition defined in claim 1 and a thickener, said mixture being premixed with water or other hardening liquids in an amount such as to have in advance a moldable fluidity

3. The moldable refractory composition of the premixed type according to claim 2, characterized in that said thickener is an organic cellulose compound and / or a copolymer of isobutyl leno-maleic anhydride.

4. A method for applying with a wet gun a moldable refractory composition »characterized in that it comprises the steps of tempering said moldable refractory composition defined in claim 1 with water or other hardening liquids to have a moldable fluidity; transporting the warm mixture to a spray applied spray nozzle by means of a pump »adding a coagulant and compressed air to said warm mixture in said spray nozzle applied with a gun; and spraying the hot mixture through said coating nozzle applied with a gun.

5. A method for applying a moldable refractory composition with a wet gun, characterized in that it comprises the steps of transporting the pre-blended moldable refractory composition defined in claims 2 or 3 to a spray nozzle applied by a pump; adding a coagulant and compressed air to said moldable refractory composition of the premixed type in said revetment nozzle applied with pißtola; and applying the hot mixture through the said spray nozzle applied with a gun.