Manufacturing method of zircon castings and zircon castings

Abstract

To provide: a method for manufacturing a zircon-cast product, capable of molding without separating the structure of the zircon-cast product, and capable of effectively inhibiting cracking that occurs during drying; and the zircon-cast product in which the separation of the structure and the occurrence of cracking are inhibited.SOLUTION: A method for manufacturing a zircon-cast product includes a casting step of casting a zircon-cast material, which is mainly composed of zircon, to obtain the zircon-cast product. The zircon-cast material contains: 20 to 40 mass% of zircon particles having a particle diameter of 1 to 5 mm; 25 to 45 mass% of zircon particles having a particle diameter of 0.1 to 1 mm; and 25 to 40 mass% of zircon particles having a particle diameter of 0.1 mm or less. A content of zircon particles having a particle diameter of 10 μm or less is 5 to 10 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a zircon casting that can be used in various furnaces and a method for producing the same. [Background technology]

[0002] Zircon refractories are used in steelmaking, glass manufacturing, etc., and are produced, for example, by firing zircon castings under appropriate conditions. By using the casting method, it is possible to obtain large zircon refractories and irregularly shaped zircon refractories that are difficult to press-form.

[0003] For example, Patent Document 1 (JP Patent Publication No. 06-157150) proposes a zircon-based monolithic refractory for pouring, which is made by adding 0.2 to 2.0 weight percent silica sol, calculated as SiO2, and 0.005 to 1.0 weight percent light-burned magnesia to 100 weight percent refractory mixture containing zircon raw material as the main aggregate.

[0004] The pourable zircon-based monolithic refractory described in Patent Document 1 is said to be able to harden at room temperature by adding light-burned magnesia as a hardener, and to be able to reduce components such as Al2O3, CaO, MgO, and Na2O, which easily react with zircon, from the joints as much as possible, thereby improving hot strength. In addition, it is said that by imparting appropriate fluidity and hardenability, it is possible to suppress a decrease in corrosion resistance due to a decrease in hot strength.

[0005] Furthermore, Patent Document 2 (Japanese Patent Application Laid-Open No. 55-116680) proposes a slag-added zircon-based monolithic refractory in which 0.3 to 5 percent by weight of converter slag is added to a zircon-based monolithic refractory containing 40 to 90 percent by weight of zircon.

[0006] In the slag-added zircon-based monolithic refractory described in Patent Document 2, it is said that by adding converter slag to the zircon-based monolithic refractory, adhesiveness and sinterability are improved, and physical properties such as bending strength and compressive strength can be improved. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 06-157150 [Patent Document 2] Japanese Patent Application Publication No. 55-116680 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the zircon-based monolithic refractory for pouring described in Patent Document 1 and the slag-added zircon-based monolithic refractory described in Patent Document 2 do not take into consideration the separation of the structure during molding or the occurrence of cracks during drying, and the casting of these refractory raw materials has not been considered.

[0009] Because zircon has a high specific gravity, it is extremely difficult to cast raw materials containing 25% or more by mass of zircon. This difference in specific gravity can cause the raw material to separate into upper and lower parts during casting, resulting in the formation of different microstructures, which has been a serious problem. This problem is particularly pronounced for large or irregularly shaped products that are difficult to press-form. In other words, there are currently no methods for producing zircon castings that can be molded without microstructure separation and that effectively suppress cracking during drying, nor any zircon castings that suppress microstructure separation and cracking.

[0010] In view of the above-mentioned problems in the prior art, an object of the present invention is to provide a method for producing a zircon casting that can be molded without causing structural separation and that can effectively suppress cracks that occur during drying, and to provide a zircon casting that suppresses structural separation and cracks. [Means for solving the problem]

[0011] In order to achieve the above object, the present inventors have conducted extensive research into the composition of zircon-based casting raw materials, and as a result have discovered that it is extremely important to precisely optimize the particle size composition of the zircon raw material, thereby arriving at the present invention.

[0012] That is, the present invention provides: a casting step for casting a zircon-based casting material containing zircon as a main component to obtain a zircon-based casting product; The zircon casting raw material contains 20 to 40 mass% of zircon particles having a particle diameter of 1 to 5 mm, 25 to 45 mass% of zircon particles having a particle diameter of 0.1 to 1 mm, and 25 to 40 mass% of zircon particles having a particle diameter of 0.1 mm or less, The content of zircon particles having a particle size of 10 μm or less is 5 to 10 mass %. The present invention provides a method for producing a zircon casting, characterized by the following:

[0013] By incorporating 20-40% by mass of zircon particles with a particle size of 1-5 mm, 25-45% by mass of zircon particles with a particle size of 0.1-1 mm, and 25-40% by mass of zircon particles with a particle size of 0.1 mm or less, the amount of added water and the amount of fine powder are optimized, preventing structural separation and cracking during drying. Furthermore, by incorporating 5-10% by mass of zircon particles with a particle size of 10 μm or less, fluidity is improved, allowing for dense packing while reducing water, thereby imparting high strength while preventing structural separation.

[0014] In the method for producing a zircon-based cast product of the present invention, it is preferable to add alumina cement and / or hydraulic alumina to the zircon-based casting raw material so that the total content of the alumina cement and / or hydraulic alumina is 2 to 3 mass %. By adding 2 to 3 mass % of alumina cement and / or hydraulic alumina, it is possible to impart even higher strength to the fired zircon-based cast product obtained by firing the zircon-based cast product.

[0015] The present invention also provides The composition contains 20 to 40 mass% of zircon particles having a particle size of 1 to 5 mm, 25 to 45 mass% of zircon particles having a particle size of 0.1 to 1 mm, and 25 to 40 mass% of zircon particles having a particle size of 0.1 mm or less, containing 5 to 10 mass% of zircon particles having a particle size of 10 μm or less; Also provided is a zircon casting characterized by:

[0016] The zircon castings of the present invention can be suitably produced by the method for producing zircon castings of the present invention, and although they are mainly composed of zircon particles with a high specific gravity, the grain size composition of the zircon particles is precisely optimized, thereby extremely effectively suppressing the occurrence of structural separation and cracking. As a result, by firing the zircon castings of the present invention under appropriate firing conditions, it is possible to obtain fired zircon castings with excellent mechanical properties and reliability.

[0017] The zircon-based cast product of the present invention preferably contains alumina cement and / or hydraulic alumina, and the total content of the alumina cement and / or hydraulic alumina is preferably 2 to 3 mass %. By adding 2 to 3 mass % of alumina cement and / or hydraulic alumina, it is possible to impart even higher strength to a fired zircon-based cast product obtained by firing the zircon-based cast product. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a method for producing a zircon casting that can be molded without causing structural separation and that can effectively suppress cracks that occur during drying, and a zircon casting in which structural separation and cracks are suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0019] Representative embodiments of the method for producing a zircon casting and the zircon casting of the present invention will be described in detail below, but the present invention is not limited to these.

[0020] 1. Manufacturing method of zircon castings The method for producing a zircon casting of the present invention involves casting a zircon casting material containing zircon as the main component to obtain a zircon casting. The method for producing a zircon casting of the present invention will be described in detail below.

[0021] (1) Zircon casting material The zircon casting material used in the method for producing a zircon casting product of the present invention is most characterized by the controlled particle size and content of zircon particles.

[0022] (1-1) Main component (zircon particles) The zircon casting raw material contains 20-40 mass% zircon particles with a particle size of 1-5 mm, 25-45 mass% zircon particles with a particle size of 0.1-1 mm, and 25-40 mass% zircon particles with a particle size of 0.1 mm or less. The content of zircon particles with a particle size of 10 μm or less is 5-10 mass%. The zircon particles with a particle size of 10 μm or less are included in the zircon particles with a particle size of 0.1 mm or less.

[0023] By incorporating 20-40% by mass of zircon particles with a particle size of 1-5 mm, 25-45% by mass of zircon particles with a particle size of 0.1-1 mm, and 25-40% by mass of zircon particles with a particle size of 0.1 mm or less, the amount of added water and the amount of fine powder are optimized, preventing structural separation and cracking during drying. Furthermore, by incorporating 5-10% by mass of zircon particles with a particle size of 10 μm or less, fluidity is improved, allowing for dense packing while reducing water, and high compressive strength can be achieved while preventing structural separation.

[0024] The content of zircon particles having a particle size of 1 to 5 mm is preferably 20 to 40 mass%, more preferably 25 to 35 mass%. The content of zircon particles having a particle size of 0.1 to 1 mm is preferably 25 to 45 mass%, more preferably 30 to 40 mass%. The content of zircon particles having a particle size of 0.1 mm or less is preferably 25 to 40 mass%, more preferably 30 to 40 mass%. The content of zircon particles having a particle size of 10 μm or less is preferably 8 to 10 mass%. If more than 10 mass% of fine zircon particles having a particle size of 10 μm or less are added, the fine zircon particles may float and cause separation.

[0025] The zircon particles may have any particle size and content within the specified ranges. The method for producing the zircon particles and the particle shape are not particularly limited as long as they do not impair the effects of the present invention, and various conventionally known zircon particles can be used.

[0026] For example, if it is difficult to obtain coarse zircon particles derived from natural minerals, zircon pellets with particle sizes of 1 to 5 mm obtained by artificially crushing, granulating, firing, crushing, and classifying zircon sand can be used as coarse particles. For zircon particles with particle sizes of 0.1 to 1 mm, crushed zircon pellets and / or crushed zircon brick waste can be used. For zircon particles with particle sizes of 0.1 mm or less, zircon sand can be used, and for fine zircon particles with particle sizes of 10 μm or less, zircon flour, zircon pax, etc. can be used.

[0027] (1-2) Optional additives Alumina cement and / or hydraulic alumina can be added as optional additives. The total content of alumina cement and / or hydraulic alumina is preferably 2 to 3 mass%. Adding 2 to 3 mass% of alumina cement and / or hydraulic alumina can impart even greater strength to the zircon-based cast sintered product obtained by firing the zircon-based cast product. By setting the total content to 2 mass% or more, the effect of improving strength can be achieved, and by setting it to 3 mass% or less, a decrease in the load-softening point of the zircon-based cast sintered product obtained by firing the zircon-based cast product can be suppressed.

[0028] Furthermore, alumina, alumina-silica, and silica particles can be used in combination as the zircon casting raw material. The particles used as the alumina, alumina-silica, and silica particles are not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known particles can be used.

[0029] Additionally, clay may be added as needed. The amount of clay added can be adjusted as appropriate, but can be, for example, 0.5 to 1.5% by mass. Adding 0.5 to 1.5% by mass of clay can reduce tissue separation.

[0030] (2) Casting process The zircon casting material described above can be cast into a desired mold to give it any desired shape, and after a drying step, the zircon casting of the present invention can be obtained.

[0031] To ensure smooth casting during the casting process, it is preferable to add an appropriate amount of water to adjust the fluidity of the zircon casting material. For example, by adding 3 to 8 mass% of water and kneading the materials, a good zircon casting material can be obtained. Note that the added water is subsequently dried and removed, and is therefore not included in the components of the zircon casting product of the present invention.

[0032] In addition, a dispersant may be added as needed. The amount of dispersant added may be adjusted appropriately. For example, the amount of dispersant added may be 0.01 to 0.1 quality % of dispersant can be added. The type of dispersant is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known dispersants can be used.

[0033] In the method for producing a zircon-based casting of the present invention, even though the main component is zircon particles with a large specific gravity, the particle size composition of the zircon particles is precisely optimized, making it possible to extremely effectively suppress separation of the structure during the casting process.

[0034] (3) Drying process The zircon casting of the present invention can be obtained by drying the zircon casting formed in the casting process to remove water. Since the separation of the structure during the casting process is suppressed, the occurrence of cracks during the drying process can also be suppressed very effectively.

[0035] The drying conditions are not particularly limited as long as they do not impair the effects of the present invention, and may be appropriately adjusted depending on the composition, shape, size, etc. of the zircon casting. For example, the casting may be cured at 50°C for one day, removed from the frame, and then dried at 70°C for one day, at 140°C for two days, and at 180°C for two days.

[0036] By firing the zircon casting of the present invention under appropriate conditions, it is possible to obtain a fired zircon casting that not only has a homogeneous structure but is also free from defects such as cracks and exhibits high compressive strength.

[0037] 2. Zircon castings The zircon casting of the present invention is obtained by the method for producing a zircon casting of the present invention.

[0038] The main components and optional additive components of the zircon casting are as described above. However, by including 20 to 40 mass% zircon particles having a particle size of 1 to 5 mm, 25 to 45 mass% zircon particles having a particle size of 0.1 to 1 mm, 25 to 40 mass% zircon particles having a particle size of 0.1 mm or less, and 5 to 10 mass% zircon particles having a particle size of 10 μm or less, the occurrence of separation of the structure and cracking is extremely effectively suppressed.

[0039] As a result, by firing the zircon casting of the present invention under appropriate firing conditions, it is possible to obtain a zircon casting with excellent mechanical properties and reliability. More specifically, a zircon casting fired under appropriate firing conditions can be imparted with a compressive strength of 140 MPa or more, and by optimizing the composition of the zircon casting, the compressive strength can be increased to 180 MPa or more.

[0040] Representative embodiments of the present invention have been described above, but the present invention is not limited to these, and various design modifications are possible, all of which are included in the technical scope of the present invention. [Example]

[0041] Example Raw materials were prepared in the proportions shown in Table 1 as Examples 1 to 8, and zircon-based casting materials were obtained. The values ​​shown in Table 1 are in mass %. Water and a dispersant were then added to each raw material, and the mixture was thoroughly kneaded. The amount of water added was kept constant at 5.5 mass %, and the amount of dispersant added was kept constant at 0.05 mass %. The zircon-based casting materials, which had appropriate fluidity, were then cast into a mold to obtain a plate-shaped zircon-based casting product measuring 230 mm × 114 mm × 65 mm.

[0042] Each of the resulting zircon castings was then cured at 50°C for one day, removed from the frame, and dried at 70°C for one day, at 140°C for two days, and at 180°C for two days to obtain a zircon casting according to the present invention. Each of the zircon castings was then fired at 1500°C for five hours to obtain a fired zircon casting.

[0043] [Table 1]

[0044] [evaluation] The castability of the zircon casting material having each composition, the state of the zircon castings, and the strength of the fired zircon castings were evaluated.

[0045] (1) Separation of the top and bottom during casting The appearance of the cast surface of the fired product was used to evaluate the state of separation between the top and bottom during casting. A ◎ was given if no layer of separated fine powder was visible on the cast surface, a 〇 was given if a layer of separated fine powder was visible on the cast surface with a thickness of <1 mm, and an × was given if a layer of separated fine powder was visible on the cast surface with a thickness of ≥1 mm. The results are shown in Table 1.

[0046] (2) Presence or absence of cracks after drying After drying, the castings were evaluated for the presence or absence of cracks based on their appearance and the condition of their cut surfaces. A score of ◯ was given for cases where no cracks were found on either the appearance or the cut surface, and an × was given for cases where cracks were found on the appearance or the cut surface. The results are shown in Table 1.

[0047] (3) Compressive strength The compressive strength of the fired zircon cast sintered product was measured based on JIS R2206 (Testing method for compressive strength of refractory bricks). The results are shown in Table 1.

[0048] Comparative Example Zircon casting raw materials, zircon cast products, and fired zircon cast products were obtained in the same manner as in the Examples, except that the raw materials were prepared in the proportions shown in Table 1 as Comparative Examples 1 to 5. Evaluations were also carried out in the same manner as in the Examples. The results are shown in Table 1.

[0049] The evaluation results shown in Table 1 reveal that in all Examples (Examples 1 to 8), separation of the upper and lower parts (structural separation) during casting was extremely effectively suppressed. In particular, Examples 1 to 6, which contained 8 mass% of fine zircon particles with a particle size of 10 μm or less, were evaluated as Excellent. On the other hand, Example 7, in which the content of fine zircon particles with a particle size of 10 μm or less was 5 mass%, and Example 8, in which the content of fine zircon particles with a particle size of 10 μm or less was 10 mass%, were evaluated as Excellent. However, all Comparative Examples (Comparative Examples 1 to 5) were evaluated as Poor, demonstrating a clear separation-suppressing effect of the present invention. Here, Example 7 did not exhibit a sufficient separation-suppressing effect compared to Examples 1 to 6 due to the low content of fine zircon particles, while Example 8 contained a large amount of fine zircon particles, resulting in slight floating of the fine zircon particles, and therefore Examples 7 and 8 were evaluated as Excellent.

[0050] Furthermore, with regard to the presence or absence of cracks after drying, all examples were evaluated as ◯, confirming a significant crack suppression effect. On the other hand, in Comparative Examples 3 and 4, in which the content of fine zircon particles with a particle size of 10 μm or less was less than 5 mass%, cracks after drying were suppressed, but separation of the upper and lower parts during casting could not be suppressed. Comparative Examples 1 and 2 contained 8 mass% of fine zircon particles with a particle size of 10 μm or less, but the proportion of zircon particles with other particle sizes was not optimized, and were evaluated as × from the perspectives of both separation of the upper and lower parts during casting and cracks after drying.

[0051] From the above results, it is clear that in order to suppress both separation of the upper and lower parts during casting and cracking after drying, it is extremely important that the zircon casting material contain 20 to 40 mass% zircon particles with a particle size of 1 to 5 mm, 25 to 45 mass% zircon particles with a particle size of 0.1 to 1 mm, 25 to 40 mass% zircon particles with a particle size of 0.1 mm or less, and 5 to 10 mass% zircon particles with a particle size of 10 μm or less. Furthermore, from the results in Table 1, it is clear that the fired zircon castings obtained by firing the zircon castings of the present invention have compressive strengths of 140 MPa or more.

Claims

1. a casting step for casting a zircon-based casting material comprising zircon, alumina cement and / or hydraulic alumina, clay, and a dispersant to obtain a zircon-based casting; The zircon casting raw material contains 20 to 40 mass % of zircon particles having a particle diameter of 1 to 5 mm, 25 to 45 mass % of zircon particles having a particle diameter of 0.1 to 1 mm, and 25 to 40 mass % of zircon particles having a particle diameter of 0.1 mm or less, The content of zircon particles having a particle diameter of 10 μm or less is 5 to 10 mass %, The total content of the alumina cement and / or the hydraulic alumina is 2 to 3 mass %, The content of the clay is 0.5 to 1.5% by mass, The content of the dispersant is 0.01 to 0.1 mass %; A method for producing a zircon casting, characterized by:

2. A zircon casting comprising zircon, alumina cement and / or hydraulic alumina, clay, and a dispersant, The composition contains 20 to 40 mass% of zircon particles having a particle diameter of 1 to 5 mm, 25 to 45 mass% of zircon particles having a particle diameter of 0.1 to 1 mm, and 25 to 40 mass% of zircon particles having a particle diameter of 0.1 mm or less, Contains 5 to 10 mass % of zircon particles having a particle diameter of 10 μm or less, The alumina cement and / or the hydraulic alumina are contained in a total amount of 2 to 3 mass %, The clay is contained in an amount of 0.5 to 1.5% by mass, The dispersant is contained in an amount of 0.01 to 0.1% by mass. Zircon castings characterized by:

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