JPS5811555B2 - Groove lining structure of a groove-type induction furnace for metal melting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the groove lining structure of a groove-type induction furnace for metal melting.

It is well known that a working pot is generally attached to a galvanizing tank installed in a continuous galvanizing line or the like, and that zinc ingots are melted in this working pot.

Such a working pot is equipped with a so-called groove-type induction furnace at its lower end, and zinc is melted by electrical energy caused by the secondary induction action of an alternating current of an inductor coil attached to the induction furnace, and this molten zinc is injected. The ductor coil is moved to the working pot while being circulated in a groove-shaped runner around the ductor coil.

In such a groove-type induction furnace, the heat generating part is concentrated in the groove, so the temperature of the molten metal in the groove is 50% higher than that in the working pot.
The temperature rises by ~200°C, and the refractories in the grooves are required to meet correspondingly stricter conditions.

That is, such refractories generally include: 1) Excellent corrosion resistance and low leakage with zinc.

2) The connective tissue (bonding state, strength) of the structure is excellent, the distribution of constituent minerals (uniformity, intervening substances) is also good, and the size and shape of crystal grains are uniform.

3) Low porosity and air permeability.

4) Low expansion coefficient, high mechanical strength (compressive strength, bending strength), and high vibration resistance.

5) It is resistant to thermal spalling due to thermal deterioration and does not cause cracks due to chemical changes with molten zinc or decomposition gas.

6) Excellent heat resistance (fire resistance), low thermal conductivity, and excellent insulation properties.

7) Easy to mold.

It is necessary to satisfy the following conditions.

By the way, in order to block the inductor of such a slotted hole induction furnace for melting zinc with a refractory material, conventional stamping methods, pouring methods, etc. are widely used.

That is, in the stamp method, as shown in Figs. 1 to 3, a core (wooden frame) 4 forming a runner for dissolving zinc is assembled in a rectangular shape inside a furnace shell 1, and an inductor coil 2 is installed inside it. After that, stamp material (high alumina A12O3
78.2%, 5iO2 (13%) 3 with a rammer, and after molding, the core 2 is removed from the frame to form a runner as shown in the figure (note that 5 in the figure is a zinc-free plug). be).

However, in this method, the stamp material is applied with a rammer in layers, so the connective tissue of the refractory tends to form a layered structure compared to the runner for zinc dissolution, and there are also problems with the tamping method, such as the rammer pressure and the rammer pressure. As it is easily affected by the shape and the degree of construction by experts, sufficient construction management is required.
If construction management is incorrect, lamination may occur on the surface of the refractory, cracks may occur due to insufficient filling during construction, and cracks will grow during drying, forcing zinc to seep into the refractory. There is.

On the other hand, in the pouring method described above, the furnace shell 1 is
Castable (chamots quality, A12O348%) inside
, 5iO2 42%) with water and pour it in, and after drying, the core 4 is removed from the frame. Although this method is easier to construct than the stamp method, as it can be easily constructed into a predetermined shape. Compared to bricks, the molding pressure is lower and the moisture content is higher, so the porosity is larger, and molten zinc forms pores (closed pores, open pores) in the refractory at low or high temperatures.
It easily penetrates into the liquid, and has poor resistance to erosion by melt.

In addition, the bonded part has lower fire resistance and corrosion resistance than aggregate, so
Because the refractory tends to erode and promote the matrix, it tends to cause structural spalling (cracks and peeling) due to its poor leakage and corrosion resistance against molten zinc, making it difficult to obtain a uniform structure. Castable has the disadvantage that grain separation and binder bias occur during the manufacturing process, which tends to cause variations in the constructed structure and uneven construction in the constructed structure.

Furthermore, regarding the construction method, lamination is likely to occur due to these factors, and chemical bonding has the disadvantage that a uniform structure cannot be obtained due to movement of the binder during natural drying or heating drying after construction. There is.

In any case, conventional methods tend to cause cracks and structural spalling due to poor installation or drying of the refractories, and problems such as short-circuit corrosion of inductor coils due to penetration of zinc into the refractories. It had the disadvantage of being easy to invite.

The present invention was developed as a result of various studies in view of the current situation.
This is a new groove lining structure for metal melting induction furnaces that has not been seen before, and its basic feature is a shaped refractory that integrates the runner and socket around the inductor coil. It consists of a fixed refractory and is surrounded by an unshaped refractory.

Next, one embodiment of the present invention will be explained with reference to FIGS. 4 to 7. First, what is shown at 10 in the figure is a furnace shell, and insulating bricks 15 are laid on the hearth of this furnace shell, and on the side walls. Inductor coil insertion holes 16a and 16b are formed, and a heat insulating board 16 is placed on the inner surface of the inductor coil insertion holes 16a and 16b.

Further, the heat insulating brick 15 has a low expansion fixed brick 17.
A shaped refractory 14 having an integrated socket 18 and runner 19 as shown in FIG. 7 is supported and fixed above it.

That is, this shaped refractory 14 has a handle shape as a whole, and a socket 18 is formed on its upper surface portion 14a, and a U-shaped lower end portion 14b has a runner 19 formed therein. ,
Both ends of this runner 19 communicate with the socket 18, respectively.

On the other hand, an inductor coil 12 whose outer periphery is insulated is inserted through the insertion hole 16a on one side of the side wall, and the inductor coil 12 passes through the opening 20 of the shaped refractory 14 and reaches the insertion hole 16b on the other side. .

A monolithic refractory 13 is filled in the furnace shell 10,
The area around the shaped refractory 14 is hardened,
In this case, if an appropriate expansion allowance such as ceramic fiber paper is provided on the contact surface of the shaped refractory 14 with the monolithic refractory 13, the monolithic refractory 1
3, thermal stress on the shaped refractory 14 due to the expansion, and generation of cracks can be appropriately prevented.

The materials used for the shaped refractories 14 and the monolithic refractories 13 include fused silica, silicon nitride, graphite, etc. In this case, the shaped refractories 14 and the monolithic refractories 13 may be made of the same material. desirable.

These refractories are dense, have low expansion properties, have excellent fire resistance and corrosion resistance, and are easy to construct, which fully satisfy the above-mentioned conditions for refractories.

Next, to explain the construction process of the present invention, first, the hearth of the furnace shell 10 is lined with insulating bricks 15, and the side walls are lined with insulating boards 16, and then fixed bricks 17 are set on the insulating bricks 15, and then vibration molding is performed in advance. The socket 18 and the runner 19 are formed into one body by a method, and the fired shaped refractory 14 is set and fixed on the fixed brick 17.

At this time, the shaped refractory 14 must be set so that its upper end 14a is aligned with the upper end of the furnace shell 10 on the same horizontal plane.

After setting the shaped refractory 14 in this way, the side wall insertion hole 1
The inductor coil 12 is inserted from 6a, passed through the opening 20 of the shaped refractory 14 to the other side insertion hole 16b, and fixed.

Thereafter, a well-kneaded unshaped figure 1 is placed inside the furnace shell 10.
3 is poured in, and the monolithic refractory 13 is fixed using a vibrator or a push rod.

After processing, natural curing and hot air drying are performed, and further, nichrome wire drying is performed in the runner 19 of the shaped refractory 14 to speed up moisture removal and hardening in the monolithic refractory 13.

After drying, apply mortar such as fused silica, which has low leakage with molten metal and high adhesive strength, to the upper surface of the monolithic refractory 13, that is, the joint surface with the working pot body. , which prevents molten metal from entering from the joints of the main body.

The present invention having the above-mentioned configuration is attached to the lower end of the working pot in the same manner as in the past, but according to the present invention, metal such as zinc that is gradually melted in the working pot is attached to the shaped refractory 14. From the socket 18 to the runner 19
While circulating through the runner 19, the molten zinc becomes molten zinc due to the electrical energy generated by the secondary induction action of the inductor coil 12, and returns to the working pot through the socket 18.

Note that the metal targeted by the present invention is not limited to the above-mentioned zinc, and it goes without saying that the present invention can also be applied to the case of melting metals with relatively low melting points such as Al, Pb, and Cu.

As explained above, according to the present invention, in particular, the area around the inductor coil is constructed of a shaped refractory that integrates a runner and a socket, and the area around the shaped refractory is made of an unshaped refractory. By hardening, the following effects can be obtained.

b) Compared to conventional stamping and pouring methods, cracks and structural spalling caused by poor refractory construction or drying can be prevented.

1) Problems such as short-circuit corrosion of the inductor coil due to penetration of molten zinc can be prevented.

c) Drying from within the runner using a nichrome wire or the like can be easily done and the drying time can be shortened.

D) Construction management is simplified.

e) Troubles caused by refractories are almost eliminated, which improves the service life of the inductor coil.

As described above, the present invention provides various excellent effects that have not been seen in the past, and is an industrially useful invention.

[Brief explanation of the drawing]

Figures 1 to 3 show the conventional trench type induction furnace structure, with Figure 1 being a plan view thereof, Figure 2 being a sectional view taken along line A-A in Figure 1, and Figure 3 being the same as in Figure 2. FIG. 2 is a sectional view taken along line BB of FIG. 4 to 6 show a groove-type induction furnace showing an embodiment of the present invention, FIG. 4 is a plan view thereof, FIG. 5 is a cross-sectional view taken along line C-C in FIG. FIG. 6 is a sectional view taken along line DD in FIG. 5. Further, FIG. 7 is a perspective view of the shaped refractory according to the present invention. In the figure, 10 is a furnace shell, 12 is an inductor coil, 13 is an unshaped refractory, 14 is a regular refractory, 15 is an insulating brick, 1
6 is a heat insulation board, 17 is a fixed brick, 18 is a socket, 19
2 indicates a runner, and 20 indicates an opening.

Claims (1)

[Claims] 1. A groove-type induction furnace for metal melting, characterized in that the inductor coil is surrounded by a shaped refractory that integrates a runner and a socket, and the shaped refractory is surrounded by a monolithic refractory. Groove lining structure of a groove-type induction furnace for metal melting.