JPH10267553A - Lining material for induction furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for lining an induction furnace for efficiently producing by alleviating dirty, severe and dangerous works in a fad environment of slag scraping work at a high temperature, normally operating the furnace, and maintaining the state for sufficiently performing ability. SOLUTION: An operating layer of a furnace bottom is executed in a thickness up to 50% of a bottom thickness of 30 mm or more with unshaped refractory 2 containing 25 to 55 wt.% of silicon carbideformation material, 10 to 55 wt.% of mullite material, 5 to 35 wt.% of molten quartz material and 10 to 30 wt.% of natural silica material so that total amount of the four materials is 90 wt.% or more and adding sintering assistant as needed. And, other site is executed with dry unshaped refractory 3 of alumina-mullite-silicon carbide- formation used generally to form a bottom multilayer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction furnace lining material for an induction furnace for melting and refining copper and copper alloys.

[0002]

2. Description of the Related Art Conventionally, when melting and refining metals such as copper and copper alloys, crucible furnaces containing graphite-based crucibles are mainly used, but recently a large amount of melting and refining is easily performed. Induction furnaces, which have advantages such as good work efficiency, high quality uniformity and high workability, and good work environment, have been introduced due to problems in quality control, work efficiency and work environment. Are rapidly spreading.

In an induction furnace, an electric induction coil is arranged on the outer periphery, and if necessary, a coating layer is provided inside the coil with a coil cement for protecting the coil, and a hot water leak sensor, an insulating material, and a heat insulating material are provided inside the coating layer. And the like, and a single layer of refractory material wall (lining material) is constructed and used on the innermost side. In a small furnace, a graphite crucible is installed in a small furnace, and the gap between the furnace body and the crucible is filled with a dry amorphous refractory (hereinafter referred to as a backing material). In a large furnace, a steel inner mold (hereinafter referred to as a “former”) designed to have a predetermined wall thickness is generally provided in the furnace body. After the dry-powder-shaped irregular refractory is charged into the gap with the furnace body, the irregular-shaped refractory that has been thrown in while being vibrated from the inside of the former is vibrated and filled to be used for construction. . The damage to the bottom and side walls and the dirt on the working surface of the lining often increases the maintenance work of the furnace, lowers the operation rate of the furnace, hinders the operation of the entire factory, and has a great effect. For this reason, in order to extend the life of the furnace, the refractory used here is a refractory manufactured using a specially examined refractory material.

At present, generally 5 to 20% by weight of SiC,
O ₂ 2 to 20 wt%, Al ₂ O ₃ 60~95% by weight of high alumina - suitably dry monolithic refractory addition of sintering aids of boric anhydride, if necessary in silicon carbide refractory used However, as the number of uses increases, the slag generated during the furnace operation gradually adheres and deposits on the working surface of the lining material, especially at the bottom of the furnace, where the tendency is high and the bottom of the furnace increases and the effective volume of the furnace decreases. The reduction rate reaches as much as 30% by volume. For this reason, the operation of removing the attached slag has been forced. This slag removal operation is an extremely difficult 3K operation because the slag is difficult to drop unless it is under high heat due to the coexistence of copper oxide and metallic copper, and the operation rate of the furnace also decreases. Even under such conditions, the furnace volume has increased due to work efficiency, labor saving and increased demand for large products, etc., and this phenomenon has further increased, and the work has become more severe and the frequency of maintenance work has increased. doing.

[0005] In order to solve these problems, a stable furnace operation can be performed, the operation rate is high, the running cost is low, and the aim is to work in a good environment. At present, there is a strong demand for a simple and comfortable work with less frequent work.

[0006]

In view of such a situation, the present inventors can reduce the 3K work in a bad environment such as slag removal work under high temperature, and can operate the furnace normally with the furnace operating properly. It is an object of the present invention to provide a method for lining an induction furnace and a refractory capable of efficiently producing the lining, which can maintain a state in which the refractory can be sufficiently exhibited.

[0007]

In view of the above situation, the present inventors have conducted a 3K operation, which is performed under high heat while looking into the upper part of a furnace, to remove deposits such as slag. In order to find a way to reduce the temperature and maintain a state in which the furnace can operate normally and stably and exhibit the full capacity of the furnace, the process of depositing and depositing deposits such as slag is adjusted from various angles. Was. The results proceed in the following order.

The slag generated during the furnace operation adheres to the lower part from the upper part and further to the furnace bottom part when tapping. Because of the repetition, the components of the attached slag penetrate into the structure of the lining material to form a heterogeneous layer (hereinafter, referred to as a deteriorated layer) on the surface layer. The deteriorated layer has good affinity with the slag and is easily adhered, and the degree of adhesion increases and accumulates. In particular, the operating surface of the lining material at the bottom of the furnace has a slightly lower hot water temperature, and the degree of adhesion increases. Since the adhesion to the slag and the like is good, the layered adhesion proceeds repeatedly. The deposit contains copper oxide as a main component, and is further mixed with metallic copper, and has high malleable properties when cooled. Removal of the attached slag is performed under high heat. However, when the deposition condition becomes thicker, the furnace is cooled.

As described above, the slag adheres to the structure of the lining material immediately before the slag adheres, and an altered layer is formed in the working layer.
The generated deteriorated layer has good compatibility with slag, metallic copper, and the like, easily causes an adhesion phenomenon, and increases the adhesion speed. Thereafter, almost same slag comes into contact every time. The two are easy to adjust to, and this phenomenon is repeated in the form of layered deposits. The deposited deposits are mainly composed of copper oxide and contain metallic copper. Therefore, the removal operation is extremely difficult and requires a lot of time and labor. Therefore, the removal operation is performed under high heat where removal is easy, and a typical 3K operation under high heat is performed.

[0010] While such operations are continued, adhesion and deposition proceed, the furnace capacity is reduced, and the melting efficiency is greatly reduced. As a result, electric energy is wasted and the productivity is reduced. And the current situation, such as increasing frequency.

[0011] As described above, slag adherence and accumulation are difficult in operation.
There is a major problem in production efficiency. Component composition of the refractory used in the currently most commonly SiO ₂ 15 wt%, SiC15 wt%, Al ₂ O ₃ 70 wt% of the dry monolithic refractory. The refractory is used to construct the bottom and side walls of the furnace. The present inventors have studied the characteristics of the refractory materials used and conducted further research and tests. As a result, they have found that the use of a high silica-high silicon carbide material greatly improves the penetration and adhesion of slag, The composition of the material is 25 to 55% by weight of the silicon carbide material, the mullite material 10
５５55% by weight, fused quartz material 5５〜35% by weight, natural siliceous material 10３０30% by weight. The total amount of the four is 90% by weight or more. By using a dry-type amorphous refractory to which an auxiliary agent is added, it is possible to find a great improvement in the material, and using this dry-type amorphous refractory, the bottom thickness of the furnace is 30 mm or more and the bottom thickness is 5 mm
The present invention provides a method capable of solving the present problems by performing up to 0% and performing a normal and safe operation.

(Reason for limitation) When the content of the silicon carbide material is 25 to 55% by weight and 25% by weight or less, the infiltration resistance of the slag and the anti-adhesion effect are small. If the content is less than 55% by weight, the effect is not greatly improved even if the content exceeds 55% by weight, and the material cost increases. Mullite material 10-55% by weight By combining with silicon carbide material, the structure is strengthened and the material has excellent physical properties, but 10% by weight.
Below, the effect is small, and when it is 55% by weight or more, the density tends to decrease, and the penetration of slag and the degree of adhesion to the surface layer tend to increase. Fused quartz material 5 to 35% by weight Fused quartz material has an effect of enhancing heat resistance spalling property and sintering power, but if it is less than 5% by weight, efficiency is small, and if it exceeds 35% by weight, corrosion resistance is deteriorated. Natural siliceous material 10 to 30% by weight The natural siliceous material enhances the residual expandability when hot. Improves sintering shrinkage due to heat reception during use of refractory material and prevents cracks, but less than 10% by weight has little effect, 30% by weight
This is because, when it exceeds, the structure of the lining material during use becomes weak. Silicon carbide material, mullite material, fused quartz material,
And the total amount of natural siliceous material is more than 90% by weight.
This is because the characteristics of the lining material according to the present invention are impaired when the total amount of the lining is less than 90% by weight. The lining according to the invention is applied to the bottom of the furnace to a thickness of at least 30 mm and up to 50% of the bottom thickness. If the thickness of the furnace bottom member is 30 mm or less, if the melting of the furnace bottom member progresses, damage including the phenomenon of partial lifting will increase. Further, damage is not caused up to a thickness of 50% or more of the furnace bottom thickness.

[0013]

EXAMPLES The values of the chemical components of the raw materials used in the examples are shown in Table 1.

[Table 1] Table 2 shows the particle size configuration values of the example materials.

[Table 2] Table 3 shows the compounding ratio of the material of the present invention used in the examples and the general material as a comparative example.

[Table 3]

An embodiment of the present invention will be described below. The test specimen of the present invention was adjusted to the particle size composition shown in Table 2 by using the specified materials shown in Table 1 at the compounding ratio shown in Table 3,
1% by weight of boric anhydride was added as a sintering aid and dry-mixed with a mixer to obtain a test material.

As a molding method, molding by dry vibration filling was performed. That is, a mold in which a stainless steel metal case having a thickness of 1 mm is inserted in a steel frame of 250 × 40 × 65 mm is fixed on a shaking table (equipped with a Eurus motor having a frequency of 1800 times / minute), and the static pressure is set to 5 mm. The molded body was heated at 800 ° C. for 10 hours in order to maintain the shape, and then taken out of a stainless steel metal case to obtain a test body. Table 4 shows the test results.

[Table 4]

In the working examples of the present invention, the materials of the examples of the present invention shown in Table 3 were added to the materials of Table 3 and the comparative materials were each added with 1% by weight of boric anhydride to the materials of Table 3 and mixed with a mixer. Dry mixing is performed to produce dry amorphous refractories.

First, 50% of the thickness is cast at the lowest part of the furnace bottom according to Table 3 of the comparative material, and then the material 3 of the present invention is placed on the upper part.
Is cast to the remaining 50% thickness, a steel former is placed on top of this, and a dry non-conform material of the current item, which is a comparative material, is put between the furnace body and the former (predetermined furnace side wall thickness). While applying impact vibration from the inside of the former and building it by vibrating and filling with the side wall, insert the starting block, energize the former and heat it up, gradually raise the temperature while heating, and usually perform sinter hardening in the low temperature range 1000 from melting temperature
After raising the temperature to 1350 ° C. which is higher by 1 ° C. and holding it for 2 hours and performing high-temperature sintering only at the time of the first use, the normal melting temperature is adjusted to 1250 ° C. and the tapping is performed as usual.

FIG. 1 shows the construction of a refractory for lining as a practical embodiment of the present invention.

The operating conditions of the induction furnace used in the practical examples are described below. Furnace size 10T furnace Melting material Copper Molten temperature 1250 ℃

[Table 5]

[0020]

As shown in Table 5, the results of the practical tests show that the embodiment of the present invention (lining method of the lining material) is slower in the start of slag adhesion at the bottom and has a smaller amount of adhesion than the comparative example. The number of times of removal of the slag which adhered was 5 times and 3 times at the same number of times of use compared with the comparative example, and the number of times of cooling the furnace was also 3 times. The effect of reducing the occurrence of cracks in the wall was reduced, and the life of the furnace was not terminated due to the insertion of the wall. According to the results of this test, it is expected that the service life of the refractory and the lining material according to the present invention will be further extended.
It should be noted that the first task of the present invention is to reduce the slag adhesion and reduce the damage to the furnace wall material for safe operation and improvement of 3K work. The frequency ratio is 0.0341 ch / times for 0.0134 ch / times, and the frequency ratio is 100% for 41.3%, and the service life is 198 for 154 channels.
channel, which leads to an improvement in the service life of 128%, resulting in an improvement in the erosion efficiency and a significant contribution to the reduction of the production cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an induction furnace lining material of the present invention.

FIG. 2 is a sectional view showing another embodiment of the lining material for an induction furnace of the present invention.

FIG. 3 is a cross-sectional view showing an embodiment of a conventional induction furnace lining material.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Conventional dry amorphous refractory 2 Irregular refractory according to the present invention 3 Dry amorphous refractory for side wall

Claims (1)

[Claims] 1. A silicon carbide material of 25 to 55% by weight, a mullite material of 10 to 55% by weight, a fused quartz material of 5 to 35% by weight, and a natural siliceous material of 10 to 30% by weight. If necessary, the operating layer at the bottom of the furnace is made of an amorphous refractory to which an appropriate sintering aid is added, if necessary for a refractory composed of 90% by weight or more.
mm and a thickness of up to 50% of the bottom thickness, and the other part is made of a commonly used alumina-mullite-silicon carbide dry amorphous refractory to form a bottom multilayer structure. Lining material for induction furnaces.