Method for manufacturing hardened monolithic refractory body, and monolithic refractory

Abstract

To provide a method for manufacturing a monolithic refractory-hardened body capable of being easily installed and having the desired durability and heat-spalling resistance, and to provide a monolithic refractory.SOLUTION: A method for manufacturing a monolithic refractory-hardened body includes: a kneading step (steps S2, S3, S4, and S5) of kneading a refractory raw material, water, and an air volume regulator to produce a monolithic refractory; and a molding step (step S6) of pouring the monolithic refractory into a construction area, curing the monolithic refractory poured into the construction area, and drying the monolithic refractory to form a monolithic refractory-hardened body having a shape corresponding to the shape of the construction area. In the kneading step (steps S2, S3, S4, and S5), a tap flow value, which is an indicator of the fluidity of the monolithic refractory, is made to be 150 mm or more and 200 mm or less, and the amount of air contained in the monolithic refractory is 1 vol.% or more and 10 vol.% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a hardened monolithic refractory body, and to a monolithic refractory. [Background technology]

[0002] A hardened monolithic refractory is a molded hardened body obtained by pouring a kneaded mixture (hereinafter referred to as "monolithic refractory") made by kneading refractory raw materials, admixtures, water, etc., into the area to be worked on and hardening it to form a shape. Examples of methods for working hardened monolithic refractories include pouring, spray repair, and press-fitting. Regardless of the work method, since monolithic refractories have fluidity, they can be worked relatively easily even if the shape of the area to be worked on is complex. Furthermore, even if a highly skilled worker is not available, monolithic refractories can be worked on the area to be worked on. Therefore, it is expected that the use of hardened monolithic refractories as refractories will continue to increase in the future.

[0003] Hardened monolithic refractories are used under harsh conditions, such as being exposed to high-temperature molten metal, being corroded by molten slag, and constantly being affected by sudden temperature changes and physical impacts, etc. Therefore, hardened monolithic refractories are required to have high durability and high resistance to heat spalling.

[0004] Conventionally known manufacturing processes for hardened monolithic refractories do not include a firing step, resulting in higher porosity than shaped refractories such as refractory bricks, and therefore tend to have lower durability than refractory bricks. Furthermore, the high porosity leads to uneven pore size distribution, which can lead to reduced heat spalling resistance of the hardened monolithic refractory. In particular, when the monolithic refractory contains carbon, which has extremely low affinity for water, a large amount of water is required to ensure the fluidity of the monolithic refractory during pouring. If the amount of water is large, many pores are formed within the molded, hardened monolithic refractory when the monolithic refractory is dried and the water evaporated. This can result in a decrease in the density of the hardened monolithic refractory, potentially reducing its durability and heat spalling resistance.

[0005] Therefore, efforts have been made to improve the durability and heat spalling resistance of hardened monolithic refractories. For example, Patent Document 1 describes a hardened monolithic refractory intended to improve the heat spalling resistance of the hardened monolithic refractory, and a method for producing the same. In this method, a flowable monolithic refractory is produced by adding water, an antifoaming agent, and an air entraining agent (AE agent, sometimes referred to as an air entraining agent) to a powder composition and kneading the mixture, and the resulting mixture is cured to produce the hardened monolithic refractory. Furthermore, X-ray CT (computed tomography) is performed on the hardened monolithic refractory. The closed porosity of the hardened monolithic refractory produced as described above is calculated based on the captured images. Note that "closed pores" refers to pores formed inside the hardened monolithic refractory that are not connected to the outside of the hardened monolithic refractory. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-92339 Summary of the Invention [Problem to be solved by the invention]

[0007] In the manufacturing method disclosed in Patent Document 1, water, an antifoaming agent, and an air-entraining agent are added to the powder composition during the kneading stage to control the closed porosity of the hardened monolithic refractory material, thereby improving the heat spalling resistance of the hardened monolithic refractory material. However, there are several parameters that affect the porosity and pore volume of the hardened monolithic refractory material. For example, the type of kneader, the combination of raw materials, the water kneading time, and the temperature all affect the amount of air contained in the monolithic refractory (slurry), which in turn affects the porosity and pore volume of the hardened monolithic refractory material produced by drying the monolithic refractory. Furthermore, changes in the amount of air contained in the monolithic refractory material affect the fluidity of the monolithic refractory, improving or worsening its workability. The manufacturing method disclosed in Patent Document 1 does not take into consideration the workability of the monolithic refractory, and it is not possible to predict the porosity or pore volume of the hardened monolithic refractory during the mixing stage of the monolithic refractory, making it difficult to manufacture a hardened monolithic refractory having the desired durability and heat spalling resistance.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a method for producing a hardened monolithic refractory body that is easy to work with and has the desired durability and heat spalling resistance, and an monolithic refractory body. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides: [1] A kneading process for producing a monolithic refractory material by kneading refractory raw materials, water, and an air content adjuster for adjusting the amount of air to be mixed; and a process for pouring the monolithic refractory material into a construction site, curing the monolithic refractory material poured into the construction site, and drying the monolithic refractory material. LetThis is a method for manufacturing a hardened amorphous refractory body, which includes a molding process in which the amorphous refractory is molded into a hardened amorphous refractory body of a shape that corresponds to the shape of the application area, and in the kneading process, the tap flow value, which is an indicator of the fluidity of the amorphous refractory, is set to 150 mm or more and 200 mm or less, and the amount of air contained in the amorphous refractory is set to more than 1 volume% and 10 volume% or less. [2] The kneading process includes a measuring process for measuring the amount of air contained in the monolithic refractory, and an adjusting process for adjusting the amount of air contained in the monolithic refractory to more than 1 volume % and not more than 10 volume % by adding an additional antifoaming agent as the air content adjuster to the monolithic refractory and kneading it when the amount of air measured in the measuring process exceeds 10 volume %, and for adjusting the amount of air contained in the monolithic refractory to more than 1 volume % and not more than 10 volume % by adding an additional air entraining agent as the air content adjuster to the monolithic refractory and kneading it when the amount of air measured in the measuring process is 1 volume % or less. [3] A fluid monolithic refractory having at least a fire-resistant refractory raw material, water, and an air content adjuster that adjusts the amount of air mixed in, wherein the tap flow value, which is an indicator of fluidity, is 150 mm or more and 200 mm or less, and the amount of air mixed in is more than 1 volume % and 10 volume % or less. [4] The refractory raw materials include at least a binder, a fine aggregate, a coarse aggregate, and a carbon raw material, and the air content adjuster includes at least one of a dispersant, an air entraining agent, and an antifoaming agent. [3] A monolithic refractory material as described in [3]. [5] The amount of the dispersant added is 1 part by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate, the amount of the air entraining agent added is 0.1 part by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate, the amount of the antifoaming agent added is 0.01 part by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate, and the amount of the water added is 10 parts by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate. [Effects of the Invention]

[0010] According to the present invention, it is possible to produce a monolithic refractory with good fluidity, and improve the workability of the monolithic refractory. Furthermore, since the amount of air contained in the monolithic refractory can be controlled within an appropriate range, it is possible to produce a hardened monolithic refractory having the desired durability and heat spalling resistance in the molding process. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a flowchart showing an example of a method for producing a monolithic refractory hardened body according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] An example of an embodiment of the present invention (hereinafter referred to as this embodiment) will be described below. One example of the hardened monolithic refractory of this embodiment is a hardened monolithic refractory containing a carbon raw material. The manufacturing method of the hardened monolithic refractory of this embodiment mainly comprises a kneading step and a molding step. The kneading step is a step of manufacturing a monolithic refractory, which is a flowable mixture, by kneading a refractory raw material with water and an air content adjuster. The molding step is a step of pouring the monolithic refractory into the application area, and then curing the monolithic refractory. Allow to harden, then Dryness Let This is a process for molding the monolithic refractory into a monolithic refractory hardened body having a shape corresponding to the shape of the work area by the above-mentioned method. In the following explanation, first, the raw materials used in the method for manufacturing the monolithic refractory hardened body of this embodiment will be explained, and then the method for manufacturing the monolithic refractory hardened body of this embodiment will be explained. In addition, the monolithic refractory hardened body may also be referred to as a molded hardened body.

[0013] The refractory raw materials preferably include at least a binder, fine aggregate, coarse aggregate, and a carbon raw material. In this embodiment, fine aggregate refers to aggregate that passes through a 5 mm mesh sieve conforming to JIS Z 8801-1:2019, Test Sieves - Part 1: Metal Wire Sieves. In other words, fine aggregate refers to aggregate with a particle size of 5 mm or less. Coarse aggregate refers to aggregate with a particle size exceeding 5 mm.

[0014] The binder binds the refractory raw materials together. Examples of binders include alumina cement, hydraulic transition alumina, silicates, and phosphates. Any of these may be used as the binder, or multiple types of binders may be used. The amount of binder in the refractory raw materials is not particularly limited, but is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to the total amount (100 parts by mass) of the refractory raw materials excluding the coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0015] The fine aggregate is a raw material that primarily imparts fire resistance to the hardened monolithic refractory body, and is preferably a conventionally used refractory powder material. Examples of fine aggregate include quartz raw materials, diatomaceous earth, fused quartz, and siliceous ultrafine powder, silica-alumina raw materials such as clay minerals and anhydrous aluminum silicate, alumina raw materials such as bauxite, diaspore, alumina shale, calcined alumina, sintered alumina, fused alumina bubbles, and ultrafine alumina powder, spinel raw materials such as spinel and chromium iron salt, magnesia raw materials, dolomite raw materials, zircon raw materials, zirconia raw materials, silicon carbide raw materials, silicon nitride raw materials, aluminum nitride raw materials, boron carbide raw materials, titanium boride raw materials, and zirconium boride raw materials. Any of these raw materials may be used as the fine aggregate, or a mixture of multiple raw materials may be used. The amount of fine aggregate in the refractory raw material is not particularly limited, but is preferably 65 parts by mass or more, more preferably 75 parts by mass or more, and even more preferably 85 parts by mass or more, based on the total amount (100 parts by mass) of the refractory raw material excluding coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0016] The coarse aggregate is a raw material that primarily imparts fire resistance to the hardened monolithic refractory body, and examples of the coarse aggregate include alumina, magnesia, and spinel. Any of these raw materials may be used as the coarse aggregate, or a mixture of multiple raw materials may be used. The amount of coarse aggregate in the refractory raw materials is not particularly limited, but is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less, based on the total amount (100 parts by mass) of the refractory raw materials excluding the coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0017] The carbon raw material increases the durability and heat spalling resistance of the hardened monolithic refractory body. Examples of the carbon raw material include coal, coke, pitch, artificial graphite, natural graphite, carbon black, and amorphous carbonaceous raw materials. Examples of natural graphite include scaly graphite, flake graphite, and earthy graphite. Any of these raw materials may be used as the carbon raw material, or a mixture of multiple raw materials may be used. The amount of the carbon raw material in the refractory raw material is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, based on the total amount (100 parts by mass) of the refractory raw materials excluding the coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0018] Furthermore, the refractory raw material may contain various additives in addition to the binder, fine aggregate, coarse aggregate, and carbon raw material. Examples of additives include fibers, set modifiers, thickeners, and anti-separation agents. These additives may be conventionally known. The content of each additive in the refractory raw material is determined in design depending on the composition of the monolithic refractory hardened body to be produced. In other words, the type and amount of additive to be added to the refractory raw material can be determined depending on the composition of the monolithic refractory hardened body to be produced.

[0019] The type of water used in this embodiment is not particularly limited, and may be industrial water or tap water at room temperature of about 20° C. When producing a monolithic refractory, the amount of water added to the refractory raw materials is preferably 10 parts by mass or less in terms of the total amount (100 parts by mass) of the refractory raw materials excluding the coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0020] Examples of the air content adjuster include dispersants, AE agents (sometimes called air entraining agents), and antifoaming agents, and it is preferable to use at least one of them.

[0021] Dispersants function to disperse various raw materials in monolithic refractories in water. Examples of dispersants include sodium tripolyphosphate (STPP), citric acid (CA), carboxylates, and sodium naphthalenesulfonate formaldehyde condensate (FDN). When a dispersant is added to monolithic refractories, the amount of dispersant added is preferably 1 part by mass or less based on the total amount (100 parts by mass) of the refractory raw materials excluding coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0022] The air-entraining agent generates numerous fine air bubbles in the monolithic refractory, i.e., incorporates air, and may be one of those listed in the chemical admixtures for concrete specified in JIS A 6204: 2011. Examples of the air-entraining agent include MasterAir 101 (active ingredient: sodium salt of alkyloxyethylene sulfonate, manufactured by BASF Japan), MasterAir 303A (active ingredient: sodium salt of alkyloxyethylene sulfonate, manufactured by BASF Japan), MasterAir 775S (active ingredient: sodium abietic acid, manufactured by BASF Japan), CAE-20 (active ingredient: sodium salt of alkyloxyethylene sulfonate, manufactured by BASF Japan), and Vinsol (registered trademark) (active ingredient: sodium abietic acid, manufactured by Kao Corporation). When adding an AE agent to an unshaped refractory, it is preferable that the amount of AE agent added be 0.1 parts by mass or less based on the total amount (100 parts by mass) of the refractory raw materials excluding coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0023] Antifoaming agents suppress the formation of air bubbles in monolithic refractories or eliminate air bubbles that have formed in monolithic refractories. Antifoaming agents are primarily composed of surfactants, and examples of such antifoaming agents include fatty acid surfactants, fatty acid ester surfactants, phosphate ester surfactants, silicone surfactants, and nonionic surfactants. Other examples of such antifoaming agents include polyalkylene glycol derivatives and polyether compounds. More specifically, examples of such antifoaming agents include Masterair 404 (manufactured by BASF Japan Ltd.) and its series, and Flolic® DF325 (manufactured by Flolic Co., Ltd.) and its series. When adding an antifoaming agent to a monolithic refractory, the amount of antifoaming agent added is preferably 0.01 parts by mass or less based on the total amount (100 parts by mass) of the refractory raw materials excluding the coarse aggregate, i.e., the binder, fine aggregate, and carbon raw material.

[0024] In this embodiment, it is preferable to use a combination of two or more of the dispersants, air-entraining agents, and antifoaming agents, and it is more preferable to use all three. This is because using all three allows the various raw materials contained in the monolithic refractory to be dispersed almost uniformly in water, and it is relatively easy to adjust the fluidity of the monolithic refractory and the amount of air in the monolithic refractory to within the above-mentioned numerical ranges. Furthermore, it is preferable to select and use dispersants, air-entraining agents, and antifoaming agents that are suitable for the binder and carbon raw material used in producing the monolithic refractory hardened body. Note that the combination of these raw materials may be a conventionally known combination.

[0025] FIG. 1 is a flowchart showing an example of a method for producing a monolithic refractory hardened body according to an embodiment of the present invention. In the flowchart shown in FIG. 1, first, refractory raw materials are added to a kneader (not shown) and dry-kneaded (step S1, dry-kneading step). As described above, the refractory raw materials contain multiple types of raw materials. Therefore, by dry-kneading the refractory raw materials using the kneader, the various raw materials of the refractory raw materials are mixed almost uniformly. Dry-kneading means kneading the refractory raw materials without adding water. The dry-kneading time is set in advance depending on the amount of monolithic refractory, the type of kneader, etc.

[0026] Water and an air content adjuster are added to the kneader and further kneaded (step S2, water kneading step). The amount of water and the amount of air content adjuster added in the water kneading step of step S2 are each determined in design depending on the amount of monolithic refractory, the type of kneader, etc. The water kneading time is set in advance depending on the amount of monolithic refractory, the type of kneader, etc. Note that after adding water and an air content adjuster to the kneader and mixing them, the refractory raw material may be added to the kneader and kneaded with water.

[0027] When the air content regulator is a solid, it may be blended with the refractory raw material during dry mixing. When the air content regulator is a liquid, it is preferably blended with water during water mixing.

[0028] Next, the fluidity of the monolithic refractory and the air content in the monolithic refractory are measured (step S3, measurement step). This is because the amount of water contained in the refractory raw material varies depending on the humidity and the lot of the refractory raw material, and even if the designed amounts of water and air content adjuster are added to the refractory raw material, the desired fluidity and air content may not be achieved. In this embodiment, the flow value (referred to as the tap flow value) described in the physical test method for alumina cement for refractories specified in JIS R 2521:1995 is used as an indicator of the fluidity of the monolithic refractory. When evaluating the fluidity of a monolithic refractory based on the tap flow value, the monolithic refractory is sampled from the kneader and the tap flow value of the monolithic refractory is measured in accordance with the physical test method for alumina cement for refractories specified in JIS R 2521:1995. In addition, the air content of the monolithic refractory material sampled from the mixer is measured in accordance with the pressure test method for air content of fresh concrete - air chamber pressure method specified in JIS A 1128:2020.

[0029] Then, it is confirmed or determined whether the tap flow value of the monolithic refractory is 150 mm or more and 200 mm or less, and whether the air content of the monolithic refractory is 1 vol % or more and 10 vol % or less (step S4, determination step). If the tap flow value or air content of the monolithic refractory is outside the above-mentioned numerical ranges, an air content adjuster is added to the monolithic refractory so that the tap flow value and air content of the monolithic refractory fall within the above-mentioned numerical ranges (step S5, adjustment step). In other words, the fluidity of the monolithic refractory and the air content in the monolithic refractory are adjusted by the amount of air content adjuster added to the monolithic refractory. On the other hand, if the tap flow value or air content of the monolithic refractory is within the above-mentioned numerical ranges, the process proceeds to the molding step of step S6 without adding an air content adjuster to the monolithic refractory.

[0030] Here, the reasons for setting the tap flow value and air volume within the above-mentioned ranges and the method for adjusting these values ​​will be explained. If the tap flow value is less than 150 mm, it may be difficult to pour the monolithic refractory into the application area in the molding process described below. In other words, due to low fluidity, application efficiency may deteriorate, increasing the risk of insufficient filling of the monolithic refractory into the application area. The application area is the area where the monolithic refractory is filled and hardened, and may be, for example, a space surrounded by a formwork so that the monolithic refractory hardens to a shape corresponding to the shape of the application area.

[0031] Conversely, if the tap flow value exceeds 200 mm, the high fluidity makes it easier to pour the monolithic refractory into the space inside the formwork, for example, but the aggregate in the monolithic refractory may sink to the bottom of the formwork due to gravity. In other words, sedimentation may occur, increasing the risk of a decrease in the strength of the hardened monolithic refractory.

[0032] Therefore, in this embodiment, in the adjustment process of step S5, the fluidity of the monolithic refractory is adjusted by adding additional air content adjusters. Specifically, when the tap flow value is less than 150 mm, a dispersant and an air-entraining agent are added as air content adjusters. That is, the dispersant maintains the dispersion state of the various raw materials in the monolithic refractory, while the air-entraining agent generates numerous fine air bubbles in the monolithic refractory, thereby adjusting the fluidity of the monolithic refractory. Note that the fluidity of the monolithic refractory tends to improve as the number of air bubbles in the monolithic refractory increases, i.e., as the air content increases. The specific amounts of dispersant and air-entraining agent added are preferably determined depending on the type of dispersant and air-entraining agent, the composition of the monolithic refractory, and the ambient temperature. On the other hand, when the tap flow value exceeds 200 mm, an antifoaming agent is added as an air content adjuster.

[0033] If the air content in the monolithic refractory is less than 1% by volume, the porosity of the monolithic refractory hardened body, which is a molded hardened body produced in the molding process described below, may be excessively low. The monolithic refractory hardened body expands and contracts with temperature changes, causing stress inside the monolithic refractory hardened body. The pores in the monolithic refractory hardened body deform when the above-mentioned stress occurs, functioning to relieve the stress. In other words, if the porosity of the monolithic refractory hardened body is excessively low, it becomes difficult to relieve the above-mentioned stress when it occurs, and as a result, the heat spalling resistance of the monolithic refractory hardened body may be reduced.

[0034] Conversely, if the air content exceeds 10% by volume, the density of the hardened monolithic refractory body will decrease, which may significantly reduce the breaking strength, i.e., the durability of the hardened monolithic refractory body.

[0035] Therefore, in this embodiment, in the adjustment process of step S5, the air content in the monolithic refractory is adjusted by additionally adding an air content adjuster. Specifically, when the air content is less than 1% by volume, an air-enhancing agent is additionally added as an air content adjuster. On the other hand, when the air content exceeds 10% by volume, an antifoaming agent is additionally added as an air content adjuster. More specifically, for example, for each 1% by volume of air content exceeding 10% by volume, 0.00005 to 0.00008 parts by mass of antifoaming agent is added relative to the total amount (100 parts by mass) of the refractory raw materials excluding the coarse aggregate. In this way, the air content in the monolithic refractory can be adjusted to 10% by volume or less.

[0036] Alternatively, a map or table is prepared in advance, which determines the relationship between the tap flow value and air content measured as described above and the amount of air content adjuster to be added to the monolithic refractory so that the tap flow value and air content of the monolithic refractory fall within each numerical range.Then, the amounts of the air content adjusters to be added to the monolithic refractory, i.e., the dispersant, AE agent, and antifoaming agent, may be determined based on the map or table and the tap flow value and air content measured as described above.

[0037] The addition of the air content adjuster to the monolithic refractory may be carried out in a single operation, but in order to prevent the tap flow value and air content from falling outside their respective numerical ranges, it is preferable to add the air content adjuster to the monolithic refractory in multiple additions. Each time the air content adjuster is added, it is preferable to knead the mixture with water and measure and confirm the tap flow value and air content.

[0038] The dry kneading step, water kneading step, measuring step, determining step, and adjusting step described above correspond to the kneading step in this embodiment.

[0039] Next, the monolithic refractory is poured into the construction area, for example, into a space formed by a formwork or a container, to perform pouring construction (step S6, molding process). In pouring construction into a metal melting vessel, a core is placed inside the metal melting vessel, and the monolithic refractory is poured into the metal melting vessel in this state, while vibration is applied to the metal melting vessel to prevent insufficient filling. Thereafter, in the molding process of step S6, the monolithic refractory is cured at room temperature of around 20°C and under atmospheric pressure. and harden Then, after removing the mold and the core of the metal melting container, it is further dried. Dryness Let . dry Drying is preferably carried out by raising the temperature to, for example, 100 to 200°C. In this way, a hardened monolithic refractory body having a moisture content (free water) of about 1 part by mass or less is produced. The curing time and drying time can be determined in advance depending on the composition of the hardened monolithic refractory body, the ambient temperature, the application equipment, etc. The ambient temperature means the ambient temperature when the hardened monolithic refractory body is used, and the application equipment means the equipment to which the hardened monolithic refractory body is applied.

[0040] As described above, in this embodiment, the fluidity and air content of the monolithic refractory are measured and confirmed, and then adjusted to ensure the workability of the monolithic refractory. In addition, the durability and heat spalling resistance of the monolithic refractory when it becomes a hardened monolithic refractory are adjusted or controlled. That is, in this embodiment, the durability and heat spalling resistance of the monolithic refractory when it becomes a hardened monolithic refractory are predicted at the monolithic refractory stage. Therefore, according to this embodiment, a hardened monolithic refractory that is easy to work and has the desired durability and heat spalling resistance can be manufactured. Furthermore, because the durability and heat spalling resistance of the hardened monolithic refractory when it becomes a hardened monolithic refractory are adjusted or controlled at the monolithic refractory stage, the yield when manufacturing the hardened monolithic refractory can be improved.

[0041] The monolithic refractory according to this embodiment is not particularly limited, and examples of applicable refractories include those having chemical compositions such as alumina, alumina-silica, magnesia, dolomite, spinel, alumina-spinel, alumina-magnesia, alumina-spinel-magnesia, magnesia-carbon, alumina-spinel-carbon, alumina-silicon carbide-carbon, and alumina-roseki-silicon carbide-carbon. [Example]

[0042] The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0043] In this example, an alumina-spinel-carbon monolithic hardened refractory body for use in a ladle was produced. First, powdered alumina cement was used as a binder for the refractory raw materials. The amount of binder mixed was 10 parts by mass per 100 parts by mass of the refractory raw materials. The fine aggregate was a mixture of alumina raw materials and spinel raw materials, with the amount of alumina raw materials mixed being 63 parts by mass per 100 parts by mass of the refractory raw materials, and the amount of spinel raw materials mixed being 22 parts by mass per 100 parts by mass of the refractory raw materials. Scaly graphite was used as the carbon raw material, with the amount mixed being 5 parts by mass per 100 parts by mass of the refractory raw materials.

[0044] Alumina raw material with a particle size of 30 mm was used as coarse aggregate. The amount of coarse aggregate mixed was 25 parts by mass per 100 parts by mass of refractory raw materials excluding coarse aggregate. The amount of water added was 7 parts by mass per 100 parts by mass of refractory raw materials excluding coarse aggregate.

[0045] Furthermore, a dispersant (PNT1973, manufactured by Pozzolith Solutions), an antifoaming agent (AFK-2, manufactured by Takemoto Yushi Co., Ltd.), and an air-entraining agent (AE-200, manufactured by Takemoto Yushi Co., Ltd.) were added as air content adjusters. The amount of the dispersant added was adjusted to be in the range of 0 to 1 part by mass relative to the total amount of refractory raw materials excluding coarse aggregate. The amount of the air-entraining agent added was adjusted to be in the range of 0 to 0.1 parts by mass relative to the total amount of refractory raw materials excluding coarse aggregate. The amount of the antifoaming agent added was adjusted to be in the range of 0 to 0.01 parts by mass relative to the total amount of refractory raw materials excluding coarse aggregate.

[0046] Water and an air content adjuster were added to the refractory raw materials, and the mixture was kneaded using a conventional mortar mixer to produce a monolithic refractory (slurry). More specifically, first, only the refractory raw materials were dry-kneaded using a mortar mixer. Then, water and an air content adjuster were added to the refractory raw materials, and the mixture was wet-kneaded. The dry-kneading time was set to 1 minute, and the wet-kneading time was set to 2 minutes.

[0047] Samples for the tests described below were taken from the monolithic refractories thus produced. Then, a flow test was conducted on the samples to measure the tap flow value in accordance with the physical testing method for alumina cement for refractories specified in JIS R 2521:1995. In addition, the air content of the samples was measured using an air meter in accordance with the air chamber pressure method, a pressure test method for air content of fresh concrete specified in JIS A 1128:2020.

[0048] The tap flow value and air content data were checked, and an air content adjuster was added to the monolithic refractory so that these values ​​were within the above-mentioned numerical range. For example, if the tap flow value was less than 150 mm, a dispersant and an air-entraining agent were added, and if the air content exceeded 10% by volume, an antifoaming agent was added. On the other hand, if the tap flow value exceeded 200 mm, an antifoaming agent was added, and if the air content was less than 1% by volume, an air-entraining agent was added. The mixture was then kneaded in a mortar mixer for 1 minute.

[0049] The tap flow value and air content were repeatedly measured and adjusted to ensure that the tap flow value, which indicates the fluidity of the monolithic refractory, was 150 mm or more and 200 mm or less, and that the air content in the monolithic refractory was 1 vol% or more and 10 vol% or less.

[0050] The monolithic refractory produced by the above procedure was poured into a 40 x 40 x 160 mm rectangular mold and cured for 24 hours in a constant temperature environment of 20°C and atmospheric pressure. After curing, the monolithic refractory was removed from the mold and placed in a dryer, where it was dried at 110°C for 24 hours. A hardened monolithic refractory was produced by the above process.

[0051] (Method for evaluating durability of hardened monolithic refractories) The durability of the hardened monolithic refractory material was measured in accordance with the flexural strength test method for refractory bricks specified in JIS R 2213:2005. That is, a three-point support bending test was performed on the hardened monolithic refractory material using an autograph to measure the bending strength of the hardened monolithic refractory material, and the bending strength was used as an index of the durability of the hardened monolithic refractory material. The threshold value of the bending strength is determined by design, and in this example, it is preferably 5 MPa or more. If the strength after drying is 5 MPa or more, the hardened monolithic refractory material can be removed from the frame without any problems and can be used without initial peeling.

[0052] (Method for evaluating the heat spalling resistance of hardened monolithic refractories) The hardened monolithic refractory was fired in a coke breeze at 1400°C for 3 hours and then cooled in the furnace. Thereafter, the hardened monolithic refractory was removed from the coke breeze, and the propagation time of a longitudinal wave in the hardened monolithic refractory was measured using a sonic velocity method (ASTMC579, ASTMC769-80). The first elastic modulus E0 of the hardened monolithic refractory was calculated based on the propagation time of the longitudinal wave. Note that "in a coke breeze" refers to a reducing atmosphere.

[0053] The hardened monolithic refractory body for which the first elastic modulus E0 was determined was then placed in an electric furnace and heated at 1400°C for 15 minutes. The hardened monolithic refractory body was then removed from the electric furnace, water-cooled using 5°C water for 5 minutes, and then air-cooled for 10 minutes. After air-cooling, the hardened monolithic refractory body was dried at 110°C for 24 hours using a dryer. The propagation time of the longitudinal wave in the hardened monolithic refractory body was then measured again using the sonic velocity method, and the second elastic modulus E1 was determined based on the propagation time of the longitudinal wave. The second elastic modulus E1 was then divided by the first elastic modulus E0 to determine the elastic modulus ratio (E1 / E0), which was used as an index of the heat spalling resistance of the hardened monolithic refractory body. In other words, the rate of change in the elastic modulus of the hardened monolithic refractory body before and after a sudden change in temperature was used as an index of the heat spalling resistance of the hardened monolithic refractory body. Therefore, the closer the value of the elastic modulus ratio (E1 / E0) is to 1, the better the heat spalling resistance can be evaluated. The threshold value of the elastic modulus ratio (E1 / E0) is determined by design, and in this embodiment, it is preferably 0.60 or more. If the elastic modulus ratio (E1 / E0) is 0.60 or more, the hardened monolithic refractory hardly experiences peeling due to thermal spalling when used at high temperatures.

[0054] (evaluation) The evaluation results of the examples and comparative examples are summarized in Table 1. The symbol "◯" in Table 1 means that the monolithic refractory was easy to pour into the application area and applied, or that sedimentation and separation did not occur, in other words, the application was good. The symbol "×" means that the monolithic refractory was difficult to pour into the application area and applied, or that sedimentation and separation occurred, in other words, the application was poor. [Table 1]

[0055] As shown in Table 1, in Examples 1 to 5, the bending strength, which is an index of durability of the hardened monolithic refractory, was 5 MPa or more, and the elastic modulus ratio, which is an index of heat spalling resistance, was 0.60 or more. In other words, in Examples 1 to 5, hardened monolithic refractories having high durability and high heat spalling resistance could be produced. Furthermore, in Examples 1 to 5, the tap flow value of the monolithic refractories immediately after kneading was 150 mm or more and 200 mm or less, and workability was good.

[0056] In contrast, in Comparative Example 1, the air content was less than 1% by volume, so the elastic modulus ratio, which is an index of heat spalling resistance, was less than 0.60, and the heat spalling resistance of the hardened monolithic refractory was insufficient. Furthermore, the tap flow value was less than 150 mm, so the workability of the monolithic refractory was poor. In Comparative Example 2, the tap flow value was 150 mm or more and 200 mm or less, so the workability of the monolithic refractory was good, but the air content exceeded 10% by volume, so the bending strength of the hardened monolithic refractory was less than 5 MPa, and the durability was insufficient. This is thought to be because the large amount of air contained in the monolithic refractory resulted in excessive pores being formed in the hardened monolithic refractory produced by drying it. In Comparative Example 3, the tap flow value exceeded 200 mm, so the workability of the monolithic refractory was poor. Furthermore, the bending strength of the hardened monolithic refractory was less than 5 MPa, and the durability was insufficient. This is thought to be because the tap flow value exceeded 200 mm, causing settling and separation of the monolithic refractory, resulting in a decrease in the strength of the hardened monolithic refractory. In Comparative Example 4, the tap flow value was 150 mm or more and 200 mm or less, so the workability of the monolithic refractory was good, but the air content was less than 1 vol%, so the elastic modulus ratio was less than 0.6, and the heat spalling resistance of the hardened monolithic refractory was insufficient. [Explanation of symbols]

[0057] S1 Dry mixing process S2 Water mixing process S3 measurement process S4 Judgment process S5 Adjustment process S6 Molding process

Claims

1. A method for producing a hardened monolithic refractory body, comprising: a kneading step of kneading a fire-resistant refractory raw material, water, and an air content adjuster for adjusting the amount of air to be mixed to produce a kneaded monolithic refractory; and a shaping step of pouring the monolithic refractory into a processing location, curing the monolithic refractory poured into the processing location, and drying the cured monolithic refractory to form the monolithic refractory into a hardened monolithic refractory body having a shape corresponding to the shape of the processing location, A method for producing a hardened amorphous refractory body, in which, in the kneading process, the tap flow value, which is an indicator of the fluidity of the amorphous refractory, is set to 150 mm or more and 200 mm or less, and the amount of air contained in the amorphous refractory is set to more than 1 volume % and 10 volume % or less.

2. The kneading step includes a measuring step of measuring the amount of air contained in the monolithic refractory, and an adjusting step of, when the amount of air measured in the measuring step exceeds 10% by volume, additionally adding an antifoaming agent as the air amount adjuster to the monolithic refractory and kneading the monolithic refractory to adjust the amount of air contained in the monolithic refractory to more than 1% by volume and not more than 10% by volume, and, when the amount of air measured in the measuring step is 1% by volume or less, additionally adding an air entraining agent as the air amount adjuster to the monolithic refractory and kneading the monolithic refractory to adjust the amount of air contained in the monolithic refractory to more than 1% by volume and not more than 10% by volume. A method for producing the hardened monolithic refractory body according to claim 1.

3. A flowable monolithic refractory having at least a refractory raw material having refractory properties, water, and an air content adjuster for adjusting the amount of air to be mixed therein, The tap flow value, which is an index of fluidity, is 150 mm or more and 200 mm or less, The amount of air mixed into the monolithic refractory is more than 1% by volume and not more than 10% by volume.

4. The refractory raw material includes at least a binder, a fine aggregate, a coarse aggregate, and a carbon raw material, 4. The monolithic refractory according to claim 3, wherein the air content regulator includes at least one of a dispersant, an air entraining agent, and an antifoaming agent.

5. An amorphous refractory material as described in claim 4, wherein the amount of dispersant added is 1 part by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate, the amount of air entraining agent added is 0.1 part by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate, the amount of antifoaming agent added is 0.01 part by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate, and the amount of water added is 10 parts by mass or less of the total amount of the refractory raw materials excluding the coarse aggregate.

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