JPH10267554A - Lining material for induction furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a deteriorated layer due to intrusion of stag component and deposition of stag by laying a molding, produced in a specified phase under specified conditions, on the upper part of a furnace by a dry indeterminate refractories, inserting a former of steel forms and forming a specified shape while impacting and shaking the side wall part. SOLUTION: Refractories 2 composed of 25-55 wt.% of silicon carbide, 10-55 wt.% of mullite, 5-35 wt.% of fused quartz and 10-30 wt.% of natural silicon, where the total content of these four components is 90 wt.% or above, is employed as the lining material for a furnace. In order to enhance the performance, of the retractories, water and an appropriate deflocculant are kneaded and molded integrally up to 50% of the thickness at the bottom part of the furnace. It is then heat treated at 1000 deg.C or below to produce a highly compact joint-free molding having porosity of 15% or less, which is placed on the bottom part 2 of the furnace by means of a dry indeterminate refractories 1. Finally, a former of steel forms is inserted and a specified shape is formed by impacting and shaking the side wall part.

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, melting of metals such as copper and copper alloys,
For refining, crucible furnaces containing graphite-based crucibles are mainly used, but recently, a large amount of melting and refining can be easily performed, and the work efficiency is good, and the uniformity of work quality and workability are high. Induction furnaces having advantages such as good environment have been introduced due to problems in quality control, work efficiency and work environment, and especially large furnaces 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 “form”) designed to have a predetermined wall thickness is generally provided in the furnace main body. After charging the dry-powder shaped refractory into the gap between the former and the furnace main body, the vibrator is applied from the inside of the former and the charged refractory is vibrated and filled for construction. ing. The damage to the bottom and side walls and the dirt on the working surface of the lining cause the maintenance work of the furnace to be increased and the operation rate of the furnace to be reduced, thereby hindering the operation of the entire factory and having 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 60~93% 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, slag generated during 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, the furnace bottom becomes high, the furnace effective volume decreases,
Sometimes the rate of decrease can be as high as 30% by volume. This necessitates the work of removing the attached slag. This slag removal work is extremely difficult because the deposited slag is difficult to drop unless it is under high heat due to the mixture of copper oxide and copper metal.
As well as the K work, the operating rate of the furnace is also reduced. Even under these conditions, the furnace volume has increased due to work efficiency, labor saving and increased demand for large products, and this phenomenon has further increased.The work has become increasingly severe and the frequency of maintenance work has increased. doing.

[0005] In order to solve these problems, a stable refining furnace can be produced, 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 circumstances, the present inventors have been able to reduce the 3K work in a bad environment such as slag removal work under high heat, have a normal furnace, and have a capability of refining. It is an object of the present invention to provide a method for lining an induction furnace and a refractory capable of efficiently producing an induction furnace, which can maintain a state in which the refractory can be sufficiently exhibited.

[0007]

In view of the above situation, the present inventors have further reduced the work of removing slag deposits, which is a 3K operation performed in a state of looking into the upper part of a furnace under high heat. In order to find a way to maintain the state where the furnace can be operated normally and stably, and the furnace's original capacity can be fully exhibited, the process of depositing and depositing deposits such as slag was investigated from various angles. As a result, it proceeds in the following order.

[0008] The slag generated during the furnace operation adheres from the top to the bottom and to the bottom at the time of tapping. Because of the repetition, the attached slag components penetrate into the structure of the lining material and form a heterogeneous layer (hereinafter, referred to as a deteriorated layer) on the surface layer. The altered layer has good familiarity with the slag and is easily adhered to the slag. In particular, the operating surface of the lining material at the bottom of the furnace has a relatively low temperature of the hot water, so that the degree of adhesion is high. Since the adhesion with the slag and the like is good, the layered adhesion repeatedly and repeatedly proceeds. These deposits contain copper oxide as a main component and further contain copper metal, and have high malleable properties when cooled. The operation of removing the attached slag is performed under high heat, but when a higher deposition state is reached, the furnace is cooled to perform the operation.

As described above, the adhesion of the slag causes the slag to penetrate into the structure of the lining material and form a deteriorated layer in the working layer. The generated deteriorated layer has good compatibility with slag, copper metal 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 adapt to, and this phenomenon repeats into layered deposition.
Since copper oxides are mainly contained in this deposit and copper metal is mixed, when cooled, the malleability, which is the characteristic of copper, works, and the removal work becomes very difficult and it is a laborious and severe work. Removal work under high heat is easy, and 3K work under typical high heat is performed.

[0010] While such operations are continued, adhesion and deposition progress, the furnace capacity is reduced, and the melting efficiency is greatly reduced. Electric energy is wasted and productivity is reduced. We were able to understand the current situation, such as the necessity and the frequency of the increase.

[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 for both 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. Material composition is 25 to 55% by weight of silicon carbide material and 10 to 55 of mullite material.
Wt%, fused quartz material 5 to 35 wt%, natural siliceous material 1
By using a refractory material containing 0 to 30% by weight and the combined amount of these four elements being 90% by weight or more, a great improvement in material quality could be found.

If it is necessary to add water and an appropriate curing agent to the refractory material in order to further enhance the performance of the refractory, a deflocculant is added and kneaded, and the thickness of the furnace bottom is 30 mm or more and 50% of the thickness of the furnace bottom. And then heat-treated at 1000 ° C or less and cast a high-density seamless shaped body with a porosity of 15% or less at the bottom of the induction furnace using a conventional dry amorphous refractory. After that, after constructing on the upper part, insert the former of steel formwork as before and insert it into the predetermined form (mold,
Thickness) by applying impact to the side wall and applying the slag component to the joints and the structure, the formation of a deteriorated layer due to the penetration of the slag component, the adhesion and deposition of slag can be greatly improved, and the current problems can be solved. This section provides a method for safe operation.

(Reason for Limitation) When the silicon carbide material is 25 to 55% by weight and 25% by weight or less, the slag has less resistance to infiltration and the effect of adhering to slag. If it exceeds 55% by weight, the effect is not greatly improved even if it exceeds 55% by weight, and the material cost increases. Mullite material, 10 to 55% by weight By using a material mixed with silicon carbide material, the structure is strengthened and excellent characteristics are obtained physically. However, the effect is small at 10% by weight or less, and 55% by weight. % Or more, the compactness 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 improving heat-resistant spoiling property and sintering power, but if it is less than 5% by weight, the effect is small, and if it exceeds 35% by weight, corrosion resistance is deteriorated. Natural siliceous material, 10 to 30% by weight Natural siliceous material enhances the residual expandability during hot work, improves the sintering shrinkage of the lining material due to heat reception during use of the refractory material, and prevents the occurrence of cracks. Less than 10% by weight has little effect.
If the content exceeds 0% by weight, the tissue being used becomes weaker. Silicon carbide, mullite, fused quartz, and natural quartzite materials have a combined amount of 90% by weight or more, and the combined amount of these four materials is 90%.
This is because the characteristics of the lining material of the present invention are impaired when the content is less than the weight%. The lining material of the present invention is applied to the bottom of the furnace to a thickness of 0 mm or more and 50% of the bottom thickness. Furnace bottom member thickness is 30mm
In the following cases, if the damage of the furnace bottom member progresses, the damage including the phenomenon of partial lifting will increase. 50% of the thickness of the furnace bottom
This is because no damage is caused up to the above thickness.

[0014]

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 measured particle size 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] As an example of the present invention, using the specified materials shown in Tables 1 and 2 to adjust the mixing ratio shown in Table 3, a curing agent,
1% by weight of sodium phosphate and 4% by weight of water were added as a deflocculant, and after kneading, the coarse and medium particle members were mixed. After kneading, the mixture was shaken and defoamed on a shaking table for 5 minutes. A molding raw material having a thickness of 30 to 50 mm is prepared, and 250 × 114 × 65
A molding gypsum mold of mm is fixed, and the raw materials for molding are sequentially charged into the gypsum mold while being vibrated, and molded. After removal from the mold, pre-drying is performed at 30 to 50 ° C. for 24 hours, followed by a heat treatment at 500 ° C. for 10 hours to produce.

The comparative product was adjusted to the mixing ratio shown in Table 3 using the specified materials shown in Tables 1 and 2, 1% by weight of boric anhydride was added as a sintering aid, and the mixture was dried by a mixer. The sample was mixed and used as a test material.

As a molding method, molding by dry vibration filling was performed. That is, a mold in which a 1 mm thick stainless steel metal case was inserted into a 250 × 40 × 65 mm steel frame was fixed on a shaking table (a Eurus motor having a frequency of 1800 times / minute was installed), and static pressure was applied. After shaking and filling for 5 minutes, the molded body was heated at 800 ° C. for 10 hours to maintain its shape,
It was taken out from a stainless steel metal case and used as a test body. Table 4 shows the test results.

[Table 4]

As a practical example of the present invention, the product of the present invention shown in Table 4 was used as a hardening agent and a deflocculant in an amount of 1% by weight of sodium phosphate in the same manner as in the production method of the quality characteristic value test material in Table 4. And 4% by weight of water are added, and the raw materials are prepared in the same manner. A predetermined furnace bottom block mold is mounted on a shaking table, and the prepared raw materials are gradually poured while vibrating the mold itself. After molding for 20 hours, demolding and pre-drying at 30-50 ° C. for 24 hours, 500 ° C. for 1 hour at 50 ° C.
After the temperature was raised to 0 ° C., heat treatment was performed for 24 hours to produce respective molded bodies.

After placing a molded article of a non-refractory dry refractory (Table 4) on the bottom of the induction furnace, placing the molded body in a predetermined shape in a furnace bottom block, On this, a predetermined steel former is provided. Between the former and the furnace body (thickness of the specified side wall lining material), as in the case of the bottom block material, a comparative material (Table 4) of a dry type refractory was injected, and the inside of the former was hit. Vibration is applied while applying vibration to fill and build the side wall, energize it, gradually raise the temperature and sinter it at low temperature to harden the amorphous refractory and melt the molten material. In order to enhance stability and durability, the melting temperature is raised to 1350 ° C, which is 100 ° C higher than the normal melting temperature, maintained for 2 hours to 3 hours, sintered at a high temperature, and after adjusting the temperature, use the regular Enter the furnace.

The operating conditions of the induction furnace used in the practical examples are as follows. Furnace size 10 ^T furnace Melting material Copper Molten temperature 1250 ° C

FIG. 1 shows the construction of a refractory for lining an induction furnace according to a practical embodiment of the present invention, and FIG. 2 shows a conventional system. Table 5 shows the results of the actual furnace use test.

[Table 5]

[0021]

As shown in Table 5, the results of 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 furnace bottom and has a smaller amount of adhesion than the comparative example. As a result, when the number of times of use was almost the same as that of the comparative example, the frequency of heating and cooling of the furnace was reduced because the number of times of furnace cooling and the number of times of cooling was reduced to two times. The development of cracks on the wall is reduced,
A good effect was obtained without the end of the life of the furnace due to the metal ingot. According to the results of this test, it is expected that the service life of the refractory and the lining material of the present invention will be further extended with the use of the structure. In addition, safe operation by reducing slag adhesion and minimizing damage to the furnace wall material, which are the main problems of the present invention, and improving the 3K work, are as follows.
0.0341 ch / work frequency per channel is 0.010
0ch / time and the frequency ratio is 100% or 30.8%
And the service life is 154 ch to 201 ch, leading to a 130% improvement in service life, improving melting efficiency and making a significant contribution to lower production costs.
The effect is enormous.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing an embodiment of a bottoming-in method for an induction furnace lining material of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conventional dry-type amorphous refractory (bottom part) 2 One-piece molded refractory according to the present invention 3 Dry-type amorphous refractory for side wall parts 4 Dry-type amorphous refractory using the same material as the product of the present invention

Claims (1)

[Claims] 1. A total amount of 25 to 55% by weight of a silicon carbide material, 10 to 55% by weight of a mullite material, 5 to 35% by weight of a fused quartz material, and 10 to 30% by weight of a natural siliceous material. Water and an appropriate curing agent and, if necessary, a deflocculant are added to a refractory material composed of 90% by weight or more, and kneaded raw materials are used. The refractory lining is molded using a mold, and after demolding, a heat treatment at 1000 ° C. or less is applied to form an integrally molded refractory having a porosity of 15% or less. The lowermost portion of the bottom of the induction furnace is generally used. Poured with alumina-mullite-silicon carbide dry amorphous refractory, installed as a furnace bottom operating layer on top of it, inserted a steel formwork into the furnace body and installed dry amorphous For induction furnaces characterized by having a bottom multilayer structure constructed by Upholstery.