JP5232536B2 - Refractory construction method for groove type induction heating device - Google Patents

Description

The present invention relates to a method for constructing a refractory for a grooved induction heating device used for, for example, heat insulation and heating of molten iron, and melting of metal in molten iron.

Conventionally, in a grooved induction heating device for molten iron, a powdered or granular ramming material is widely used as a refractory material for forming a flow path (runner) through which molten iron (molten metal) flows. This is to reduce the thickness of the refractory that forms the flow path as much as possible to increase the power efficiency of the groove type induction heating device. In the construction of such a thin refractory, it is called wear lining and permal lining. This is because it is difficult to separate the two refractories.
Moreover, since the ramming material used for the groove type induction heating apparatus for molten iron is used at a high temperature of 1350 to 1600 ° C., magnesia (MgO), alumina (Al ₂ O ₃ ), Al ₂ O ₃ —MgO spinel, etc. Is generally used, and a ramming material mainly composed of SiO ₂ is inferior in durability and therefore rarely used.

The ramming material used in the grooved induction heating device is sintered near the working surface exposed to high temperatures (ie, the contact surface with molten iron), so it is necessary only in the vicinity of the working surface among the ramming materials. Sintering strength is manifested. The layer thus sintered is generally referred to as a sintered layer, and the layer located on the back surface of the sintered layer is referred to as an unsintered layer.
In this way, since the unsintered layer exists on the back surface of the sintered layer, even if a crack occurs in the sintered layer for some reason, the unsintered layer is sintered by the molten iron that has entered the crack, The layer prevents further penetration of the molten iron. Therefore, the crack does not reach the iron skin covering the ramming material, and the risk of hot water leakage from the groove type induction heating device is very low.

When constructing a new refractory for such a groove-type induction heating device, a cylindrical metal core for forming a runner is installed at a predetermined position in the iron shell serving as a case, and then the metal A ramming material is inserted between the child and the iron skin, and the ramming material is squeezed using a vibrator or the like. And the space after melt | dissolving and removing this metal core becomes a runway for the molten iron heated by induction.
However, in such a state where the ramming material is simply tamped, the runner collapses when the metal core disappears.

Therefore, when starting up a grooved induction heating device with a newly built refractory, the metal core is energized, and the metal core is heated in accordance with a predetermined temperature increase schedule. A so-called sintering operation is performed in which the ramming material in contact therewith is sufficiently baked and solidified to form a sintered layer.
At the end of this sintering operation, the metal core is melted and cut, and further energization heating becomes impossible, so the sintering operation by energization heating is completed. Thereafter, it is possible to shift to normal operation by pouring molten iron into the cylindrical metal core and resuming energization of the runway with molten iron.

There are two types of induction heating furnaces for molten iron: an induction heating furnace provided with the above-described groove type induction heating apparatus and a crucible type induction heating furnace.
This crucible type induction heating furnace has, for example, a simple cylinder in which a primary coil for induction heating is arranged around a crucible that holds molten metal, as disclosed in Patent Document 1. It has a structure in which an induced current is generated in the molten metal inside the crucible having a shape (cylindrical forming form corresponding to a metal core during a sintering operation).
For this reason, there is little variation in the surface temperature of the molding mold during the sintering operation, and the temperature variation (“maximum temperature” − “minimum temperature”) is about 100 to 300 ° C. at the end of the sintering operation. Therefore, the ramming material (lined refractory material) adjacent to the mold for molding is satisfactorily sintered.

On the other hand, the groove-type induction heating apparatus that is the subject of the present invention has a runner formed in a lateral E shape around a primary coil using a UI core, as shown in Patent Document 2, for example. It has a complicated shape. For this reason, the distance between the primary coil and the runner greatly varies in each part in the groove type induction heating device, and as a result, the variation in the surface temperature of the metal core is approximately 400 to 500 ° C. at the end of the sintering operation. To reach.
At the end of the sintering operation, the high temperature part of the metal core is heated to a high temperature of approximately 1500 ° C., so that the high temperature part is melted and cut, making it impossible to heat the metal core.

As described above, since the refractory starts to be cooled in the state where the high temperature portion is cut, it is necessary to pour molten iron into the cylindrical metal core and restart the energization heating. However, at this time, the low temperature part of the metal core has generally reached over 1000 ° C. and reached 1100 ° C. or less (hereinafter referred to as 1000 to 1100 ° C. for this description). With regard to the refractory to be used, sufficient sintering strength is not obtained.
Therefore, for example, stress due to the thermal expansion of the refractory itself due to crushing of the runway due to the molten metal pressure when receiving molten iron, wear due to the molten metal flow, or the low temperature portion being rapidly heated to 1500 ° C. by the molten metal There is a possibility that the sintered layer of the ramming material sintered with the metal core may be broken due to breakage caused by the above.

Note that the term “breakage” as used herein refers to a breakage in which the unsintered layer of the ramming material is exposed to a large area at once by the molten metal, specifically, a breakage in a portion where the sintering is insufficient, This means destruction at a thin part, and this destruction is directly connected to hot water leakage from the induction heating device. As described above, there is an unsintered layer on the back side of the sintered layer, and the unsintered layer on the back side is sintered by the molten metal that has entered the crack of the sintered layer, thereby suppressing the progress of the crack. The mechanism cannot suppress the above-mentioned destruction.
Further, since the porosity of the sintered layer in the low temperature part of approximately 1000 to 1100 ° C. is not sufficiently lowered, there is a concern about the collapse of the working surface side of the ramming material due to infiltration of molten iron or the like, the structural spall, and the like. In addition, since the normal temperature of the groove-type induction heating apparatus for molten iron is approximately 1350 to 1600 ° C., it is difficult to sufficiently sinter a ramming material that can withstand this temperature at a low temperature of approximately 1000 to 1100 ° C. is there.

In order to solve this problem, a technique for improving the sinterability of only the working surface side of the refractory and a technique for forming a film are disclosed.
For example, in Patent Document 1, a net or woven fabric containing an additive (glass composition) having permeability to a refractory is attached to the outer surface of a molding mold, and this mold is used. A method has been proposed in which a refractory is lined and then heated.
Further, Patent Document 2 proposes a method in which a thin rigid coating layer that is inert to the molten metal is formed on the outer surface of the core for the groove type induction heating device by thermal spraying or the like.
In Patent Document 3, a sleeve made of a fixed refractory is formed around a core for a groove-type induction heating device, and a material for forming a glass layer is applied to the outer surface of the sleeve, and this is applied to a furnace. A method has been proposed in which a ramming material is squeezed around the periphery after being installed at a predetermined position.

JP 61-128089 A Japanese Patent Laid-Open No. 5-10585 Japanese Patent Laid-Open No. 11-201652

However, the conventional method still has the following problems to be solved.
In the method of Patent Document 1, unevenness of the additive due to the thread such as the net used is inevitable, and there is a problem that the material of the sintered layer using the additive becomes non-uniform.
In addition, when using a core for a grooved induction heating device with a complicated shape, it is difficult to attach a net or the like to the outer surface of the core, and even if it can be installed, the outer surface of the core Since a step (unevenness) is formed by wrapping a net or the like on the surface, unevenness is formed on the surface of the sintered ramming material after the core is melted and removed, which easily causes cracks in the refractory.

And, as described above, the refractory of the crucible type induction heating furnace targeted by Patent Document 1 has a simple cylindrical shape, the temperature of the forming mold is likely to be uniform, and the sintering of the ramming material proceeds uniformly. Therefore, the strength of the refractory can be improved even when the additive mainly composed of glass described in Patent Document 1 is used for sintering the ramming material. However, in the groove type induction heating device, the temperature variation during sintering is 400 to 500 ° C., and the entire ramming material in contact with the metal core cannot be sintered uniformly. Even if the agent is used, the strength of the refractory in the portion where the temperature is low (1000 to 1100 ° C.) cannot be improved.
As described above, the inventors of the present application have newly found that the strength of the refractory is insufficient even when the additive described in Patent Document 1 is used in the groove type induction heating apparatus.

Further, the method of Patent Document 2 has a problem that the coating layer is cracked due to a difference in thermal expansion between the core and the coating layer in the temperature rising process by sintering.
Furthermore, a coating layer is formed by thermal spraying, etc. However, even when heated, the coating layer is generally difficult to bond with the refractory and does not sinter together, so a bonding force is generated between the coating layer and the refractory. do not do. For this reason, when a coating layer is exposed to a molten metal flow, there exists a problem that a coating layer will be washed away by a molten metal flow. As a result, there is a problem that the sintered layer of the ramming material that is insufficiently sintered is exposed to the molten metal flow and the sintered layer is destroyed.

In the method of Patent Document 3, it is very difficult to form a sleeve made of a fixed refractory material around the core used for manufacturing the grooved induction heating device having a complicated shape, and it is impossible in practical use. .
In addition, there is a problem that the sleeve is cracked due to a difference in thermal expansion between the core and the sleeve in the temperature rising process by sintering.

The present invention has been made in view of such circumstances, and a grooved induction heating apparatus capable of holding molten iron without destroying the sintered layer in contact with the molten iron during the sintering operation of the ramming material by energizing the metal core. The purpose is to provide a refractory building method.

In the refractory building method for a grooved induction heating device according to the present invention that meets the above-mentioned object, the aggregate and the aggregates are bonded to the outer surface of a metal core for forming a runner of the grooved induction heating device. A coating material containing glass powder is applied using a binder that cures at room temperature, and the metal core to which the coating material has been applied is placed at a predetermined position in an iron skin, and then the metal core and the metal core A refractory for a groove type induction heating apparatus in which a ramming material of MgO, Al ₂ O ₃ , or a mixture of Al ₂ O ₃ —MgO spinel and MgO or Al ₂ O ₃ is put between the iron shells and hardened. A construction method,
The ramming material is, if a MgO-based, or _Al 2 _O 3 when a mixture system of -MgO spinel and MgO, said coating material comprising a MgO-based or _Al 2 _O 3 -MgO spinel said aggregate of use,
When the ramming material is Al ₂ O ₃ system, or when it is composed of a mixture system of Al ₂ O ₃ —MgO spinel and Al ₂ O ₃ , Al ₂ O ₃ system or Al ₂ O ₃ —MgO spinel. The coating material comprising the aggregate of the system is used.

In the refractory building method for a grooved induction heating device according to the present invention, the glass powder is SiO ₂ , Al ₂ O ₃ , NaO, P ₂ O ₅ , B ₂ O ₃ , K ₂ O, Na ₂ O, CaO. , MgO, and TiO ₂ , a powder having a melting point of 700 ° C. or more and 1000 ° C. or less, and the amount of the glass powder in the coating material is 15% by mass or more and 40% by mass or less. It is preferable that
In the refractory building method for a grooved induction heating device according to the present invention, the glass powder is SiO ₂ , Al ₂ O ₃ , NaO, P ₂ O ₅ , B ₂ O ₃ , K ₂ O, Na ₂ O, CaO. , MgO, and TiO ₂ powder, which reacts with the aggregate in the ramming material or the coating material and starts to generate a liquid phase at 700 ° C. or higher and 1000 ° C. or lower. In addition, the amount of the glass powder in the coating material is preferably 15% by mass or more and 40% by mass or less.

In the refractory building method for a grooved induction heating apparatus according to the present invention, the glass powder particles are preferably under 45 μm.
In the refractory building method for a grooved induction heating apparatus according to the present invention, the aggregate preferably contains 30% by mass or more of particles that are 50 μm over and 200 μm under.

The refractory building method for a grooved induction heating device according to claim 1, wherein a coating material containing aggregate and glass powder is applied to an outer surface of a metal core using a binder, Since the ramming material is put between the iron shells and hardened, the glass is cross-linked between the aggregates even at the low temperature portion where the temperature reaches only 1000 to 1100 ° C. at the end of sintering of the ramming material. A strong protective layer can be formed. Thereby, the runway collapse due to the molten metal pressure, the wear due to the molten metal flow, the collapse of the working surface side of the ramming material due to the infiltration of the molten metal and the structural spall can be prevented.
In addition, since a binder that cures at room temperature is used for applying the coating material, it can be applied and fixed directly on the surface of the metal core without using a net or woven fabric as in the past. And no unevenness of the coating material due to the stitches.
If the ramming material is MgO-based or a mixture of Al ₂ O ₃ —MgO spinel and MgO, use a coating material containing an MgO-based or Al ₂ O ₃ —MgO spinel-based aggregate, and If ramming material is a mixture system of _Al 2 _{O 3} system or _Al 2 _O 3 -MgO spinel and _Al 2 _{O 3} is, _Al 2 _{O 3} system or _Al 2 _O 3 -MgO spinel aggregate is blended Since the coating material is used, the reaction between the ramming material and the coating material can be prevented, and as a result, the occurrence of spinel expansion can be prevented. Thereby, for example, it is possible to prevent microcracks and the like from occurring in the coating layer formed of the coating material, and it is possible to maintain the effect of preventing the molten metal from infiltrating by the coating layer.
From the above, in the sintering operation of the ramming material by energizing the metal core, for example, even if the molten metal comes into contact with the sintered layer in the low temperature portion that has reached only about 1000 to 1100 ° C. It is possible to hold the molten metal without breaking the bonding layer.

In particular, since the method for building a refractory for a grooved induction heating device according to claims 2 and 3 uses a glass powder that begins to produce a liquid phase at 700 ° C. or more and 1000 ° C. or less, it is higher than this temperature, It can permeate as a liquid by capillary action between refractory materials constituting the ramming material that contacts the metal core rising to at least about 1000 ° C. and between aggregates included in the coating material. Thereby, a strong protective layer can be formed on the surface of the metal core.
Furthermore, the glass powder also crosslinks the refractory material constituting the ramming material and the aggregate in the coating material, so that the coating layer formed of the coating material adheres firmly to the surface of the ramming material and is washed away by the molten metal flow. It becomes difficult to be.
Moreover, since the amount of the glass powder in the coating material is defined, the life of the coating layer can be extended while maintaining the effect of preventing the molten metal from infiltrating. Here, the glass powder includes those that generate glass before the liquid phase is generated by heating. For example, there is a SiO ₂ —Al ₂ O ₃ —Na ₂ O type called clay. This material is crystalline (that is, not glass), but generally vitrifies at 600 ° C. or higher and begins to form a liquid phase at 700 ° C. or higher (700 to 800 ° C.).

The method for building a refractory for a grooved induction heating device according to claim 4 regulates the size of the glass powder particles, so that the glass powder can be uniformly dispersed in the aggregate in the coating material, preventing the infiltration of the molten metal. The effect can be further improved.
The refractory building method for a grooved induction heating device according to claim 5 regulates the size of the aggregate particles, so that the coating material can be satisfactorily applied to the surface of the metal core, and the coating thickness. Can be made uniform and firmly attached, and the durability against wear caused by the molten metal flow can be ensured.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is a front sectional view of a groove type induction heating apparatus using the refractory building method for a groove type induction heating apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the refractory building method for a groove-type induction heating device according to an embodiment of the present invention is performed by using a metal core 12 used for forming a runner 11 of the groove-type induction heating device 10. A coating material containing aggregate and glass powder was applied to the surface 13 using a binder, and the metal core 12 to which the coating material was applied was placed in a predetermined position in the iron skin (also referred to as a case) 14. After that, between the metal core 12 and the iron skin 14, a MgO-based, Al ₂ O _3- based, or Al ₂ O ₃ -MgO spinel and MgO or Al ₂ O ₃ mixture-based ramming material 15 is introduced. It is a method of tamping. This will be described in detail below.

First, a metal core 12 is prepared.
The metal core 12 is formed of a hollow cylinder (pipe), and has a shape (lateral B shape in front view) in which one side of two molds having round corners are connected to each other. The side in contact with the plate 16 is planar. The outer diameter of the metal core 12 is the inner width of the runner 11 formed (for example, 6 cm or more and 30 cm or less). The material of the metal core is not particularly limited as long as it can be resistance-heated by energization. However, the metal core is finally melted and mixed into molten metal (molten iron such as molten iron or molten steel). In addition, it is preferable to be made of a material that does not become an impurity, for example, casting or steel.

For example, the coating material is applied to the outer surface 13 of the metallic core 12 by brushing once or a plurality of times visually so that the thickness is in the range of 1 mm to 5 mm. In addition, if the coating thickness of the coating material is too thick, the coating material peels off, and if it is too thin, the coating material does not function.
The coating material is applied using a binder that cures at room temperature. As this binder, for example, a water-soluble organic adhesive such as starch paste is suitable, but the aggregate and glass powder are fixed to the outer surface 13 of the metal core 12 at room temperature, for example, 100 to 300. The material is not limited to this as long as it disappears or carbonizes at a heating temperature of 0 ° C. and does not function as a binder.
The added amount of the binder may be less than 1% by mass of the total amount of the coating material (external portion, outer hook, outer split).

The coating material includes an aggregate and glass powder (low-temperature molten glass) that bonds the aggregates together.
In the case of using an MgO-based refractory material for the ramming material, or an aggregate using an refractory material composed of a mixture of Al ₂ O ₃ —MgO spinel and MgO, the aggregate is either MgO-based or Al ₂ O ₃ — An MgO spinel type is used.
In the case of _Al 2 _{O 3 is} used refractory material to ramming material, or when using the constructed refractory mixture based _Al 2 _O 3 -MgO spinel and _Al 2 _{O 3} is, Al to aggregate _{A 2} O ₃ type or Al ₂ O ₃ —MgO spinel type is used.

Here, the MgO-based refractory material used for the ramming material includes, for example, 80% by mass or more of MgO (upper limit is 100% by mass), and additionally includes Al ₂ O ₃ , SiO ₂ , and CaO. is there.
Further, the Al ₂ O ₃ -based refractory material includes, for example, 80% by mass or more of Al ₂ O ₃ (upper limit is 100% by mass), and also includes MgO, SiO ₂ , and CaO.
Examples of the MgO-based aggregate include a high-purity MgO clinker, and examples of the Al ₂ O _3- based aggregate include a high-purity Al ₂ O ₃ clinker. In _addition, the aggregate of Al ₂ O 3 -MgO spinel is, for example, a high-purity _Al 2 _O 3 -MgO spinel clinker.
The Al ₂ O ₃ —MgO spinel and MgO mixture refractory material used for the ramming material is, for example, 90% by mass or more of Al ₂ O ₃ —MgO spinel and MgO (Al ₂ O ₃ —MgO spinel: 75 to 95% by mass, MgO: 3 to 20% by mass) (upper limit is 100% by mass), and others include SiO ₂ and CaO.
_Furthermore, the mixture refractory material of Al ₂ O 3 -MgO spinel and _Al 2 _{O 3,} for _example, Al ₂ O 3 -MgO spinel and _Al 2 _{O 3} of 90 wt% or more _{(Al 2} O 3 -MgO spinel : 75 to 95% by mass, Al ₂ O ₃ : 3 to 20% by mass) (upper limit is 100% by mass), and other materials include SiO ₂ and CaO.

This aggregate contains 30% by mass or more of particles of 50 μm over (on the sieve when a sieve having a sieve mesh of 50 μm is used) and 200 μm under (under the sieve when a sieve having a sieve mesh of 200 μm is used). preferable.
Here, when the aggregate particle size is under 50 μm, the aggregate particle size becomes small, and there is too little coarse aggregate to ensure the durability against wear caused by the molten metal flow, so the practical strength is low. Become. On the other hand, in the case of over 200 μm, the aggregate particle structure is too large, the workability when applying the coating material to the metal core is deteriorated, and the coating layer having a uniform thickness is applied to the surface of the metal core. It becomes difficult to adhere firmly. In addition, the above-mentioned effect becomes remarkable because an aggregate contains the particle | grains of such a magnitude | size 30 mass% or more.
In view of the above, an aggregate containing 30% by mass or more, preferably 35% by mass or more of particles that are 50 μm over and 200 μm under is used. The upper limit is not specifically defined because all of the aggregate (100% by mass) may be 50 μm over and 200 μm under, but in reality it is about 90% by mass.

The glass powder is a powder composed of at least _{three of} SiO ₂ , Al ₂ O ₃ , NaO, P ₂ O ₅ , B ₂ O ₃ , K ₂ O, Na ₂ O, CaO, MgO, and TiO _2. The melting point is preferably 700 ° C. or higher and 1000 ° C. or lower. Moreover, it is preferable that the powder has the above-described composition and starts to generate a liquid phase at 700 ° C. or more and 1000 ° C. or less by reacting with the aggregate in the ramming material or the coating material.
The composition and temperature range of the glass powder described above are determined by the fact that the temperature of the low temperature part of the metal core, which has been a problem in the past, is generally 1000 to 1100 ° C. as described above. For this reason, the composition of the glass powder is such that the melting point or the temperature at which the liquid phase begins to be generated is lower than the temperature of the low temperature part of the metal core, that is, 700 ° C. or more and 1000 ° C. or less (preferably, the upper limit Is selected to be in a temperature range of 900 ° C., further 800 ° C.). When glass powder produces | generates a liquid phase at less than 700 degreeC, when the produced | generated liquid phase will be 1000-1100 degreeC, viscosity will become low and the effect of bridge | crosslinking an aggregate etc. and producing a strong protective layer will become low. On the other hand, when a liquid phase is generated at a temperature exceeding 1000 ° C., crosslinking may not be generated at 1000 ° C. or higher.

Specific examples of the composition that satisfies the above composition and temperature range include, for example, sodium aluminosilicate glass frit and clay. In particular, when clay is used, moderate viscosity and plasticity can be imparted to the coating material, and workability is improved.
The glass powder particles are preferably under 45 μm.
Since this glass powder has a function of bonding aggregates, it is preferable to uniformly disperse it in the coating material. In order to perform this dispersion, particles under 45 μm, preferably particles under 30 μm More preferably, particles under 20 μm are used.

This glass powder is preferably contained in the coating material in an amount of 15% by mass to 40% by mass. Therefore, when the coating material is composed of aggregate and glass powder, the aggregate is contained in an amount of 60% by mass to 85% by mass.
Here, when the amount of the glass powder contained in the coating material is less than 15% by mass, the amount of the glass powder is too small, and the amount of glass for cross-linking the aggregates decreases, so that the infiltration prevention effect such as molten metal is obtained. Less. On the other hand, when the amount of the glass powder exceeds 40% by mass, the amount of the glass powder is too much and the amount of the aggregate becomes too small, so that the life of the coating material is shortened.
From the above, it is preferable that the amount of the glass powder in the coating material is 15% by mass or more and 40% by mass or less, further the lower limit is 20% by mass and the upper limit is 35% by mass.

In this way, the metal core 12 coated with the coating material is placed in the iron shell 14 placed on the base plate 16 and opened at the top and bottom, and the intervals in the front-rear direction and the left-right direction are the same. After the installation, the ramming material 15 is inserted between the metal core 12 and the iron shell 14 and hardened.
This operation is performed by repeatedly inserting a ramming material 15 between the metal core 12 and the iron skin 14 by a predetermined height and, for example, ramming with a rammer or the like, and ramming to the upper end position of the iron skin 14. The material 15 is filled. In the filling process of the ramming material 15, a cylindrical bushing (coil frame) that penetrates the iron skin 14 is inserted into the two through holes 17 and 18 formed in the metal core 12, and the coil And secure a place to insert the core.
Thus, after filling the ramming material 15 between the metal core 12 and the iron skin 14 and the bushing, the metal core 12 is energized and the temperature rise by the sintering operation is started.

Since the metal core 12 is heated by starting the sintering operation, the adhesive force and bonding force of the coating material by the binder are lost at a relatively low temperature of about 100 to 300 ° C. However, at this time, since the ramming material 15 is filled around the metal core 12, the coating material does not peel off from the metal core 12. Further, since the binding force of the binder is lost due to the temperature rise, the coating material does not crack due to thermal expansion.
At the end of this sintering operation, the high temperature part of the metal core 12 is melted and cut, making it impossible to heat by heating. At this time, sufficient sinter strength is obtained for the ramming material contacting the low temperature part. Absent. However, since a strong protective layer is formed by the coating material formed around the metal core 12, even if the molten iron is poured into the cylindrical metal core 12 and electric heating is resumed, the molten iron is still in contact. The molten iron can be retained without destroying the sintered layer.

Next, examples carried out for confirming the effects of the present invention will be described.
Here, a test will be described in which a test induction heating furnace is used instead of the grooved induction heating device, and the combination of the ramming material and the coating material is changed variously.
In this test, a water-soluble organic adhesive (starch glue) was used as a binder, and the coating material was applied to the outer surface of the metal core in a thickness of 2 mm and dried naturally. Was installed in the induction heating furnace main body, and then a predetermined ramming material was put around the metal core to be tamped. Here, when the above-mentioned binder is not used for applying the coating material, a lot of the coating material is peeled off from the metal core due to vibrations caused by the rammer when building the ramming material. It was impossible to build a ramming material while it was attached to the core. Note that the glass powder in the coating material was used to Clay _{(SiO 2 -Al 2 O 3 -Na} 2 O -based).

Next, the ramming material was sintered by energizing the metal core and raising the temperature until the metal core was dissolved.
Thereafter, a slag powder having a basicity (CaO mass% / SiO ₂ mass%) = 1.0 and a cold soot were additionally charged into the furnace, heated and melted, kept at 1400 ° C., and then the total amount of molten slag and half of the hot metal A simulation test of an actual machine was performed with one cycle as the work of discharging the gas. Here, the time required for one cycle was 6 hours, and a sample was obtained by performing this for 8 cycles for a total of 48 hours.
Then, by observing the cross sections of these samples, the minimum remaining thickness of the formed coating layer and the maximum infiltration thickness of the hot metal or slag into the ramming material were measured. The test conditions and test results are shown in Tables 1 and 2. In addition, the determination is “X” when the minimum remaining thickness of the coating layer is 0 mm and the maximum infiltration thickness of the hot metal or slag exceeds 10 mm, and “△” when the minimum remaining thickness is 0 mm or the maximum infiltration thickness exceeds 10 mm. In the case where the minimum remaining thickness is more than 1 mm and the maximum infiltration thickness is 5 mm or less, “◎” is indicated. Otherwise, “◯” is indicated.

Table 1 uses a ramming material composed of a mixture system of Al ₂ O ₃ —MgO spinel and Al ₂ O ₃ (Al ₂ O ₃ —MgO spinel: 90 mass%, Al ₂ O ₃ : 8 mass%). As a result, Table 2 shows the results of using a MgO-based (MgO: 85% by mass) ramming material.
Examples 1 to 5 shown in Table 1 are results when using a coating material containing an Al ₂ O ₃ -based aggregate using a high-purity Al ₂ O ₃ clinker, and the glass powder in the coating material The blending ratio is changed in the range of 50 to 10% by mass. On the other hand, Comparative Example 1 is a result when a coating material is not used, and Comparative Example 2 is a result when a coating material containing an MgO-based aggregate using a high-purity MgO clinker is used.

From Example 3 shown in Table 1, it was found that when the mixing ratio of the glass powder to the coating material was 25% by mass, the thickness of the molten metal or slag infiltrated into the formed coating layer was the thinnest.
In addition, as in Example 1, when the blending ratio of the glass powder exceeded 40% by mass, the formed coating layer was greatly worn, and a portion where the minimum remaining thickness was zero was generated after 48 hours of immersion.
On the other hand, as shown in Example 5, it was found that when the blending ratio of the glass powder was less than 15% by mass, the formed coating layer was less worn but the infiltration preventing effect was lowered.

In addition, Comparative Example 2 uses a ramming material composed of a mixture of Al ₂ O ₃ —MgO spinel and Al ₂ O ₃ and a coating material containing an MgO-based aggregate, so the minimum remaining thickness is 0 mm, Moreover, the maximum infiltration thickness exceeded 10 mm.
It includes a single Al ₂ O ₃ in ramming material, spinel expansion occurs by reaction with MgO aggregate of a single Al ₂ O ₃ and the coating material in the in the ramming material, fine cracks in the coating layer It is thought that because of entering.

Subsequently, Table 2 will be described.
Examples 6 to 10 shown in Table 2 are results when a coating material containing an MgO-based aggregate using a high-purity MgO clinker is used, and the blending ratio of the glass powder in the coating material is 50 to 10 Changes are made in the mass% range. On the other hand, the comparative example 3 is a result when a coating material is not used, and the comparative example 4 is a case where a coating material containing an Al ₂ O ₃ based aggregate using a high purity Al ₂ O ₃ clinker is used. It is a result.

From Example 8 shown in Table 2, even when using MgO-based ramming material and aggregate, when the mixing ratio of the glass powder to the coating material is 25% by mass, the hot metal and slag of the formed coating layer It was found that the infiltration thickness was the thinnest.
Further, as in Example 6, when the blending ratio of the glass powder exceeded 40% by mass, the formed coating layer was greatly worn, and a portion where the minimum remaining thickness was zero was generated after 48 hours of immersion.
On the other hand, as shown in Example 10, it was found that when the blending ratio of the glass powder was less than 15% by mass, the formed coating layer was less worn but the infiltration preventing effect was lowered.

In Comparative Example 4, the ramming material of MgO-based, due to the use of a coating material containing _Al 2 _{O 3} based aggregate, a minimum residual thickness is 0mm, and the addition up to infiltration thickness exceeds 10 mm.
This is because the ramming material contains simple MgO, the simple MgO in the ramming material reacts with the Al ₂ O ₃ aggregate in the coating material, spinel expansion occurs, and the coating layer has microcracks. it is conceivable that.

Next, the result of investigating the influence of the particle size of the glass powder will be described.
Here, with reference to Table 3 with respect to the results of the tests performed by changing the size of the glass powder in various ways, centering on Example 3 in which the size of the glass powder particles is under 45 μm (described as −45 μm). explain.

From Examples 3 and 11 shown in Table 3, when the glass powder particles used were under 45 μm, the result that the wear of the coating layer was particularly small was obtained. In addition, as in Example 12, when particles under 50 μm were used, they were inferior to those in Examples 3 and 11, but there was little wear of the coating layer and there was also a maximum infiltration preventing effect.
This is because the glass powder having a particle size of under 45 μm can be used to uniformly disperse the glass powder in the coating material, and as a result, the bonding state between the aggregates can be improved. to cause.

Then, the result of investigating the influence of the amount of aggregate of 50 μm over and 200 μm under (described as +50 μm and −200 μm) will be described.
Here, with reference to Table 4, the results of tests performed by changing the amount of aggregate particles in various manners will be described with a focus on Example 3 in which the amount of aggregate of 50 μm over and under 200 μm is 30% by mass. .

From Examples 3 and 13 shown in Table 4, when the amount of aggregate of 50 μm over and 200 μm under was 30% by mass or more, the result that the wear of the coating layer was particularly small was obtained. In addition, when the amount of aggregate was 20% by mass as in Example 14, although it was inferior to Examples 3 and 13, there was little wear of the coating layer and there was also a maximum infiltration preventing effect.
This is due to the fact that the effect of using the aggregate in this particle size range is conspicuous by setting the amount of aggregate of 50 μm over and 200 μm under 30% by mass or more.

The size of the glass powder particles, the size of the aggregate particles, and the amount thereof are as follows: a ramming material composed of a mixture system of Al ₂ O ₃ —MgO spinel and Al ₂ O ₃ , Al _Although the description has been made with reference to Example 3 using ₂ O ₃ -based aggregates, the same results were obtained using Example 8 as a reference when using MgO-based ramming materials and MgO-based aggregates. was gotten.
Therefore, by using the refractory building method of the grooved induction heating device of the present invention, the molten iron is not destroyed in the sintering operation of the ramming material by energizing the metal core without destroying the sintered layer in contact with the molten iron. We were able to confirm that

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the refractory building method for a grooved induction heating apparatus according to the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the present invention.
In addition, the refractory building method of the groove type induction heating apparatus shown in the above embodiment can be used for, for example, the refractory building method of the groove type induction heating apparatus provided in an induction furnace or a hot dip galvanizing pot of a thin plate. However, the present invention is not limited to this.
And in the said embodiment, although the case where a coating material was directly apply | coated to the outer surface of metal cores was demonstrated, a coating material is made of metal through the base aggregate of 1 layer or 2 layers or more. The application to the outer surface of the core is also included in the scope of the present invention. Here, the underlying aggregate to be used, the configuration is different from conventional aggregate and aggregate of the present invention (e.g., Al ₂ O ₃ or the like) can be used.

It is a front sectional view of a groove type induction heating device using a refractory building method for a groove type induction heating device according to an embodiment of the present invention.

Explanation of symbols

10: Groove type induction heating device, 11: Runway, 12: Metal core, 13: Outer surface, 14: Iron skin, 15: Ramming material, 16: Base plate, 17, 18: Through hole

Claims (5)

On the outer surface of the metal core for forming the runner of the groove type induction heating device, a coating material containing aggregate and glass powder for bonding the aggregates is applied using a binder that cures at room temperature, After the metal core to which the coating material has been applied is placed at a predetermined position in the iron skin, an MgO-based, Al ₂ O _3- based, or Al ₂ O ₃ is interposed between the metal core and the iron core. -MgO spinel and MgO or mixtures based ramming material of Al ₂ O ₃ was charged to tamp a refractory construction method of the channel induction heating device,
The ramming material is, if a MgO-based, or _Al 2 _O 3 when a mixture system of -MgO spinel and MgO, said coating material comprising a MgO-based or _Al 2 _O 3 -MgO spinel said aggregate of use,
When the ramming material is Al ₂ O ₃ system, or when it is composed of a mixture system of Al ₂ O ₃ —MgO spinel and Al ₂ O ₃ , Al ₂ O ₃ system or Al ₂ O ₃ —MgO spinel. A method for constructing a refractory for a groove type induction heating apparatus, wherein the coating material containing the aggregate of the system is used. 2. The refractory building method for a grooved induction heating apparatus according to claim 1, wherein the glass powder includes SiO ₂ , Al ₂ O ₃ , NaO, P ₂ O ₅ , B ₂ O ₃ , K ₂ O, Na ₂ O, It is a powder composed of any three or more of CaO, MgO, and TiO ₂ , having a melting point of 700 ° C. or more and 1000 ° C. or less, and the amount of the glass powder in the coating material is 15% by mass or more and 40% by mass. A method for building a refractory for a grooved induction heating device, characterized by: 2. The refractory building method for a grooved induction heating apparatus according to claim 1, wherein the glass powder includes SiO ₂ , Al ₂ O ₃ , NaO, P ₂ O ₅ , B ₂ O ₃ , K ₂ O, Na ₂ O, A powder composed of at least three of CaO, MgO, and TiO ₂ that reacts with the aggregate in the ramming material or the coating material and starts to generate a liquid phase at 700 ° C. or higher and 1000 ° C. or lower. And the amount of the said glass powder in the said coating material is 15 mass% or more and 40 mass% or less, The refractory building method of the groove type induction heating apparatus characterized by the above-mentioned. The refractory building method for a groove type induction heating apparatus according to any one of claims 1 to 3, wherein the glass powder particles are under 45 µm. . The refractory building method for a groove type induction heating apparatus according to any one of claims 1 to 4, wherein the aggregate contains particles of 50 µm over and 200 µm under in an amount of 30% by mass or more. Refractory building method for induction heating equipment.

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