JPH02169986A - Lining refractory member for induction melting furnace and furnace construction using same - Google Patents

Abstract

PURPOSE:To shorten drying time and sintering time without mixing impurity in melted metal, to increase the number of times of uses, and to prevent melting amount due to repairing from decreasing by composing a lining refractory member of a plurality of sintered layers having different sintering degrees. CONSTITUTION:After a bottom face intermediate layer 4 is formed, a molded form 2 is vertically inserted into the center of a furnace, a backup material is filled around the side face, and stamped to form a backup layer 3. Sintering, drying are conducted to complete an induction melting furnace. A plurality of sintered layers are composed of a blocklike sintered layer 20a formed at the innermost side, an intermediate sintered layer 20b not sufficiently sintered, and an unsintered layer 20c, and the backup layer 3 becomes completely unsintered layer. The innermost layer has high refractory degree, the semisintered layer disposed outside the innermost layer has satisfactory heat insulation, and altered to a sintered layer as it is used so that the durability is increased, and slag resistance is strengthened. Thus, the capacity of the number of times of melting is increased, its thermal efficiency is enhanced, and its electric efficiency can be improved.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an induction melting furnace for melting and smelting metallic minerals using high temperatures generated by an induced current induced by a high frequency or relatively low frequency current. The present invention relates to a new lining refractory member provided on the innermost surface of the lining and a method for constructing an induction melting furnace using the lining refractory member.

[Prior Art] Various types of induction melting furnaces have been used in the past to heat and melt the material to be melted in the furnace by induction heating using a high frequency current or a relatively low frequency current. FIG. 5 shows an example. The induction melting furnace 1a includes an outer frame 8 having a bottom surface and an opening at the top, an electric induction water cooling coil 5 for high frequency generation located inside the outer frame 8, and a coil cement layer 6 for holding the coil 5. , and a metal cylinder 9 which is on the innermost surface and forms a core part.

It is composed of a side intermediate layer 3a and a bottom intermediate layer 4a made of a lining material, which are formed between the coil 5 and the metal cylinder 9 to maintain this.

To make the induction melting furnace 1a with the above configuration, first put the coil 5 in the outer frame 8, harden the coil 5 with coil cement until the coil is no longer visible, and then put coil cement into the space. This is hardened by stamping or the like to form a coil cement layer 6.

Next, a lining material is added to form the bottom intermediate layer 4a horizontally.

After the annular metal cylinder 9 is placed in the center of the furnace, a lining material is placed around the outside to form the side intermediate layer 3a.

Next, the furnace top 7 is topped with a topping cement material that has the same chemical properties and coefficient of thermal expansion as the lining material.The topping is a wet method rather than a dry method, and a water glass solution is kneaded and then hammered into shape using an air rammer, etc. Next, the furnace top 7 is dried by keeping it warm at 65[° C.] for several hours.

The sintering method involves placing the metal and its small pieces in a metal cylinder and increasing the temperature at a rate of 100 [c/hr] up to 300 [°C].
1, kept at 800 [℃] for 2 hours, then 25
0 [c/hrl to raise the temperature to 1650 [℃], 165
Keep warm at 0 [℃] for 3 [hrl].

In addition to the prior art described above, there is a prior art that does not use the metal cylinder 9 (not shown), which has a general structure similar to that shown in Fig. 5, but the part into which the metal cylinder 9 is inserted. A truncated cone-shaped iron core is inserted into the core, and a refractory stamp material is inserted between the core and the coil 5 (Fig. 5), and after hardening it by stamping, etc., the furnace body is lifted up. It is designed to be heated and sintered.

[Objective of the present invention: Problems to be solved] Since the conventional induction melting furnace shown in FIG. A problem arises in that part of the cylinder 9 is immersed in the melt and mixed in as impurities. Further, there is a problem that the metal cylinder 9 gradually wears out, which shortens the life of the furnace. Although the latter conventional technique does not have the risk of contamination with impurities, it does have the problem of requiring a long drying time and sintering time to remove the moisture and binder in the refractory stamp material. Furthermore, since the entire inner surface of the furnace is made of refractory stamp material, there is also the problem that the furnace is relatively expensive. Furthermore, in the prior art, the lining refractory member made of a refractory stamp material consists of a single sintered layer, which has the disadvantages of low fire resistance, low usage frequency, and low electrical efficiency.

The present invention was created to solve the problems and drawbacks of the prior art, and it does not mix impurities into the molten metal, can be dried and sintered in a short time, can be used many times,
It is an object of the present invention to provide a refractory lining member for an induction melting furnace that does not cause a decrease in melting capacity through repair and enables a significant cost reduction, and to provide a method for constructing a furnace using the same.

[Structure of the present invention: Means for solving the two problems] In order to achieve the above-mentioned objects, the present invention provides an inner surface of a furnace body having a load-bearing structure layer, a refractory heat insulating layer, and an electric induction water cooling coil built in from the outside and having an open portion at the top. This is a refractory lining member characterized in that a plurality of layers with different degrees of sintering are formed on the innermost side in an induction melting furnace having a layer of refractory lining member on the side.

In addition to improving electrical efficiency, the method for constructing a furnace using a refractory lining member having this function is to first form a molded body, which is the base of the refractory lining member, into a truncated conical shape that tapers downward. The core and the gap 20[+u+] to [6
A refractory stamp material of SK28 or higher is uniformly mixed with a binder in a mold for forming a lining refractory member consisting of an outer frame surrounding the outer frame with a distance of 0 mm], the mold is packed, and the mold is demolded to form a mold of 100 mm. After drying at a temperature of ``c'' or higher and 400[℃] or lower to form a finished molded product (also called a sleeve),
This is inserted into the center of the furnace body from the outside, which contains a load-bearing structure layer, a refractory heat insulation layer, and an electric induction water cooling coil, and has an opening at the top, and a backup material is placed between the furnace body and the molded body. After hardening, the inside of the molded body is heated at 1 hour per hour.
The temperature was raised from 00[℃] at a rate of 300[℃] to 900[℃].
℃] to 1100['c] for about 30 minutes to 1.
5 [Hold for hours.

Next, the temperature was raised at a rate of 200 [°C] to 300 [°C] per hour, and the temperature was increased to about 30 [°C] to 1,500 [°C] to 1,700 [°C].
Furnace construction using a refractory lining member, characterized in that by holding the molded body for [minutes] to 1.5 [hours], the molded body is formed as a refractory lining member consisting of a plurality of layers with different degrees of sintering. This constitutes a method. In the method for forming the above-mentioned molded article, first, an outer molding frame is used which surrounds a core made of a truncated cone with a gap in between.

A stamp material of a general refractory material containing alumina, magnesia, spinel, and silica with an appropriate particle size (SK28 or higher or about 4F) is mixed with organic and inorganic binders and charged into the gap. Stamping. Once it reaches the top, take out the inside and leave it as it is for 24 hours.
After drying at room temperature for 48 hours, dry in a drying oven for 100%
It is completed by drying at a temperature of [°C] or more and 400 [°C] or less for an appropriate time.

The same material as the molded body may be used as the backup material, but a cheaper material 1, for example, when the molded body is made of fused magnesia, sintered magnesia clinker may be used as the backup material. . Although the ratio of the backup layer to the molding layer is appropriately set, for example, the ratio of the backup layer to about 60% is generally adopted.

[Function] By the manufacturing method as described above, a plurality of layers having different degrees of sintering are formed in the molded body. The innermost layer is a sintered layer with high fire resistance, and the outer semi-sintered layer has good heat insulation properties, and as it is used, it changes to a sintered layer, making it highly durable and durable. This increases the melting capacity, increases thermal efficiency, and improves electrical efficiency. Further, by providing a molded body and a backup layer, and forming the backup layer from an inexpensive material, it is possible to significantly reduce costs.

[Example] An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows the overall structure of an induction melting furnace 1. In FIG. 1, the same reference numerals as in FIG. 5 have the same structure or the same function, and the explanation thereof will be omitted.

The molded body 2 (the innermost layer of the molded body 2 which has been sintered becomes the inner refractory member) manufactured in advance at a different location has a shape as shown in FIGS. 2 and 3. That is, the molded body 2
consists of a hollow cylindrical body with an open top and bottom, the outer diameter is the same diameter, and the inner periphery is formed into a tapered shape that tapers downward such that d > d, and there is an even larger tapered shape at the bottom. An inclined surface is formed. As described above, this molded body 2 is formed from a core shaped like a truncated cone or polygonal pyramid, and an outer frame surrounding the core. In addition, the wall thickness t depends on the length of the cylinder, but in this example it is 20 [mm3:l to 60 [mm3:l].
mm] is adopted. As shown in FIG. 1, after forming the bottom intermediate layer 4, the molded body 2 is charged vertically into the center of the furnace, and a backup material is placed around the sides thereof as described above and stamped to form the backup layer 3. . Thereafter, sintering and drying are performed according to the temperature conditions described above to complete the induction melting furnace.

As shown in FIG. 4, the plurality of sintered layers include a brick-shaped sintered layer 20a formed on the innermost surface side, an intermediate sintered layer 20b that has not been sufficiently sintered, and a final sintered layer 20c. The backup layer 3 also becomes a completely unsintered layer. Hereinafter, some actual examples will be described in detail.

(Example 1) Spinel (SP30) is used as the stamp material. The chemical components include MgOnia 6% or more, A
l2O,: 21 [%] or less, Sin,: 1.5
[%] or less, CaO: 0.06 [%] or less 8 particle size structure (mesh) is 4 to 8 is 26.
8 [%], 8 to 35 31.0 [%],
35 to 100 is 14.9 [% 1.100 or less is 27.3 E%]. After thoroughly mixing the monolithic refractories with the above chemical composition and particle size structure in a dry state, a basic binder of 10 [%] and a warm solution of 5.5 E%]
Add and mix thoroughly with a mortar mixer. This is applied to a frame mold for a molded article as described above, with a mold size of 15 kg per use.
A uniform integral molded body 2 (FIG. 2) is formed one by one using a pneumatic rammer. The dimensions of the molded body 2 are an outer diameter of 580 [mm] and an inner diameter of approximately 520 [mm].
], height 1020 [+a+il. Molded body 2
Once it has risen, it is removed from the core and outer frame, and the molded body 2 is dried as it is at room temperature for 24 to 48 hours, and then dried in a drying oven at 100 [°C] to 100°C.
Dry at 50 [°C] for 24 hours, and further dry at 200 [°C] to 350 [°C] for 12 to 24 hours to completely remove moisture.

Next, as shown in FIG. 1, the bottom intermediate layer 4 of the furnace having the coil 5 and the coil cement layer is prepared. That is, we weighed 15 kg of the 5P30 mentioned above, spread it uniformly on the bottom surface and the surface, and while smoothing one surface, we sequentially performed surface force calibration while adding the material, and evened it with a Bosch type vibrator machine to a thickness of about 120 [mm]. Next, the molded body 2 manufactured as described above is set at the center position in the furnace.The next step is to create a backup layer 3. In this example, 5P30 is used as the backup material. there was. That is, a 5P30 stamping material is put into the gap between the coil cement layer 6 and the molded body 2, and is evenly hammered in with an iron stamping rod. After hammering is performed from above to approximately 30 [m] to 50 [+sm], the inner surface of the molded body 2 is stamped using a Bosch type vibrator machine. Finally, add 5[%] to 6[%] of 5P30 stamp material mixed with water glass No. 3 and water at a ratio of 1:1.
Add and mix, and perform construction while stamping the furnace top 7. Next, the temperature is kept at about 65 [° C.] to 100 [”c] for several hours to completely dry the furnace top 7.

Place a disc-shaped stainless steel plate or a rectangular stainless steel plate on the bottom side of the molded body 2 on the bottom intermediate layer 4, and pack enough stainless steel strips for melting on it. Add stainless steel strips one by one until the temperature is reached.

The temperature increase rate was 150[℃] per hour and 1000[℃].
℃] for about 1 hour, and then raised the temperature to 1650[℃] at 250[℃] per hour.

The sintering is then held for 1 hour to complete the sintering.

As a result of the above, molded product 2 having a wall thickness (1) of 30 mml
The brick-shaped sintered layer 20a on the innermost side is about 10 [m
m], the intermediate sintered layer 20b is about 120 [+wm], and the sintered layer 20c is about 8 [■]. A plurality of sintered layers (three layers) are formed as shown in FIG. The backup layer 3 is a completely unsintered layer, and is formed in such a state that it can be easily penetrated to the center by a metal rod of about 10 [+n+].

The metal melting furnace 1 manufactured as described above is used under the same conditions as the conventional product and repaired using the same repair method. However, in this example, no decrease in capacity was observed. In other words, it has been demonstrated that electrical efficiency is improved and the amount of metal melted is also increased.

(Example 2) Fused alumina (AR98) is used as the stamp material. This chemical component is Al2O, :97.5[
%] or more, SiO: 0.5 [%] or less.

Fe2O3: 0.1 [%] Below, the particle size is 41
The number 4 to 8 is 26.8[
%], 31.0 [%] for those between 8 and 35, 4.9 [%] for those between 35 and 100, and 27.3 [%] for those below 100.

The method for manufacturing the molded article 2 was the same as in Example 1 except that an acidic binder was used as the binder, and the construction method was also the same.

Since this example uses a high-frequency vacuum melting furnace, the sintering method is to set a carbon electrode inside the molded body 2 and heat it at 100[°C] for 1 hour.
] Heated to 1000 [℃] for about 10 hours at a temperature increase rate of 1000 [℃], kept warm for 2 hours, and then
The temperature was raised to 1550 [°C] and held there for 2 hours. After the completion of sintering, the carbon electrode is taken out, and the molded body 2 (correctly, the lining fireproof member) is prepared in the same manner as described above.
A place where metal with a ratio of 50% aluminum and 50% vanadium was melted using a high frequency vacuum melting furnace with a structure of 0 or more, which was formed from a sintered layer and an unsintered backup layer 3. No contamination of impurities was observed. In addition, the shape of the molded body 2 in this case has an outer diameter of 690 [m+
i], inner diameter 610 [l1ll], height 1130 [mml]
Met.

(Example 3) As the stamp material, electrofused magnesia (MR-IOI
Use B). This chemical component is MgO: 95.
5 [%], AL, 0. :2.5 [%], SiO
, : 0.7 [%], CaO: 1.1 [%], and the particle size structure (mesh) of 4 to 8 is 27 [%].
%] 8 to 35 is 30.5 [%] 35 to 1
00 is 15.5 [%] 100 or less is 27
．． 0 [%], 5P30 was used as the desk backup material, and the chemical composition and particle size structure were the same as in Example 1.

The construction method and sintering temperature are also the same as in Example 1.

The shape of the molded body 2 has an outer diameter of 584 [m+m] and an inner diameter of 4.
80 [mml, height 760 [mm] is used,
Cast steel was used as the molten metal. The operating temperature is 1630 [
[°C] to 1700 [°C].

The sintered layer of the lining fireproof member consisted of a plurality of layers as in Examples 1 and 2, and the backup layer 3 was not sintered. It has been demonstrated that the product can be used 98 times, compared to 50 times for the conventional product.

[Effects of the present invention] According to the present invention, the following excellent effects can be achieved.

(1) As explained in Examples 1 and 2, results were obtained in which no impurities were mixed into the molten metal.

(2) Drying and sintering time can be shortened because the molded body is manufactured separately and the backup layer and the molded body are separated.

(3) The number of times of use increases; for example, as seen in Example 3, an increase of about two times is observed.

FIG. 2 is an axial cross-sectional view showing the body structure.

(2) 1a...Induction melting furnace, 2... Molded body (inner refractory member), 3... Backup layer.

4... Bottom intermediate layer, 5... Coil, 6... Coil cement layer, 7... Furnace top, 8... Outer frame body, 9...
・Metal cylinder.

(4) No change in melting capacity is observed after repair, and electrical efficiency can be improved.

(5) By making the backup material from an inexpensive material different from that of the molded body, costs can be reduced.

[Brief explanation of the drawing]

Claims (1)

[Scope of Claims] 1) An induction melting furnace that has a load-bearing structure layer, a fireproof insulation layer, and an electric induction water cooling coil built in from the outside, and has a layer of lining refractory material on the inner surface of the furnace body that has an open part at the top. A refractory lining member for an induction melting furnace, characterized in that the refractory lining member forms a plurality of sintered layers having different degrees of sintering. 2) A 20 [
A refractory of SK28 or higher is placed in a mold for forming an inner refractory member, which is surrounded by a truncated conical core tapering downward and the outer frame, separated by a distance of 60 mm] to 60 mm. The stamp material is uniformly mixed with a binder, packed into a mold, demolded, and dried at a temperature of 100 [°C] or more and 400 [°C] or less. After inserting from the open part, positioning the center, and densely filling the space between the furnace body and the molded body with backup material, the temperature inside the molded body is raised at a rate of 100 [°C] to 300 [°C] per hour. , maintained at 900 [°C] to 1100 [°C] for about 30 [minutes] to 1.5 [hours], then raised the temperature at a rate of 200 [°C] to 300 [°C] per hour, and further to 1500 [°C]. Approximately 30 [minutes] to 1.5 [hours] at 1700 [℃]
A method for constructing an induction melting furnace using a lining refractory member, characterized in that by holding the molded body, the molded body is formed into a plurality of layers having different degrees of sintering.