JPH0364409A - Impeller for stirring molten metal - Google Patents

Abstract

PURPOSE:To manufacture an impeller for stirring molten metal having excellent erosion resistance, heat spalling resistance and long service life by forming at least blade parts with a metal-impregnating refractory where the specific ratio of metal is impregnated to the refractory porous body. CONSTITUTION:The impeller 2 having four blade parts is fitted to tip part of a rotary shaft 1 with a ring 6 and holding metal tool 7. At least blade parts in this impeller 2 are formed with a metal-impregnating refractory, in which 10-80vol.% of metal (e.g. Fe-18Cr, etc.) is impregnated to the refractory porous body. By this method, the impeller 2 for stirring molten metal with the heat spalling resistance drastically improved without lowering the high temp., is obtd.

Description

[Detailed description of the invention] [Industrial application field] This invention is inspired by an impeller for stirring molten metal.

[Conventional technology]

In the refining process, various types of stirring 11 are used to promote the refining reaction.
! machine is used.

For example, in the K RjM mechanical molten steel stirring method in the deflowing step of hot metal pretreatment, desulfurization agents such as calcium carbide and soda ash are added to the hot metal pot, and the impeller of the stirrer is immersed.
Rotate this. The simultaneous rotation of the impeller creates a vortex depression in the center of the hot metal bath surface, which injects the desulfurization agent and accelerates the progress of the desulfurization reaction.

The impeller consists of a rotating shaft connected to a driving means and several blades connected to the rotating shaft. Conventional impeller blades are protected from damage caused by stirred molten metal! /JIl-, refractories are used. As this refractory, fired refractories, castables, castables containing metal fibers, etc. are used.

[Invention or problem to be solved]

However, the above-mentioned conventional refractories are quite porous and have low airtightness. Therefore stirring 1'1! Damage due to melting and penetration of melt can easily occur. The penetrated melt is
It forms a low melting point compound with the refractory, causing significant wear and tear on the impeller. In particular, erosion occurs in the blade portion due to the stirring of the molten metal.

In addition, since the impeller is repeatedly immersed and pulled up, the temperature changes drastically and thermal spalling occurs.

Therefore, impellers have a short lifespan and frequently require replacement or repair.

In order to solve the above-mentioned problems, an object of the present invention is to provide an impeller having a long life and excellent melting resistance and anti-spalling property.

[Means to solve the problem]

In order to solve the above-mentioned problems, an impeller according to the present invention has a rotating shaft connected to a driving means and several blade parts connected to the rotating shaft, and the impeller has a refractory porous body made of metal. A metal-impregnated refractory impregnated with is provided at least in the wing portion.

[For production]

In the impeller according to the present invention, since the pores of the refractory porous body in the blade portion are filled with metal, the density of the blade portion is increased, and the impeller is resistant to erosion by stirring molten metal and intrusion of molten material.

Moreover, since the metal-impregnated large-sized material is filled with the pores of the refractory porous body or the metal fittings, the p1 spalling resistance is greatly improved without reducing the high temperature strength. That is, by impregnating the refractory with metal, the thermal conductivity of the refractory is improved, the heat dispersibility is improved, and distortion due to temperature difference (2ω11<, thermal expansion difference) between the inside and outside of the refractory is less likely to occur.

As a result, thermal spalling resistance is improved.

In addition, the amount of metal impregnated is 10 to 80% by volume based on the volume of the refractory, or 50 to 1% by volume based on the volume of the refractory.
Select so that the effect of front pressure or 111 will be applied in the case of 00% Takashi. 1L (The reason for this is that it is used as a refractory impeller.) The amount of open pores that can be created while maintaining the strength of the corpse is 15 to 60% by volume, and the amount of open pores that can be This is because it is necessary to impregnate 50% or more of the metal by volume, so the lower limit of the amount of impregnation is 10% by volume and the maximum is 80% by volume.

〔Example〕

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 is a perspective view showing an impeller related to an embodiment of the present invention, Fig. 2 is a schematic diagram showing the outline of the RF desulfurization process, and Figs. 3, 4, and 5 are related to the present invention. FIG. 2 is a schematic diagram shown to explain a method of manufacturing an impeller.

An impeller 2 having four blades symmetrically about the rotation axis 1 is attached to the light ☆; 14 of the rotation axis 1 by a ring 6 and a holding fitting 7.

In FIG. 2, a predetermined amount of hot metal 4 is accommodated in a hot metal ladle 3. A desulfurizing agent 5 is added to the hot metal 4. Weld tip 4 (This impeller 2 is M'/A.

The rotation shaft 1 of the impeller 2 is provided with a drive means (not shown).

Next, an example of a method for manufacturing an impeller will be described.

Method for manufacturing an impeller A metal-impregnated refractory impeller having a shape of four blades as shown in FIG. 1 is manufactured. The porosity of the porous refractory material is, for example, 20% by volume. This is impregnated with about 40% by volume of Fe-18er under predetermined conditions. After impregnation, the outer surface is cut to form a metal-impregnated, large-sized impeller with predetermined dimensions.

The method for manufacturing the impeller will be explained in detail below.

Example of additional manufacturing] Referring to Fig. 3, Fig. 3a shows the structure of the holding fitting 7 attached to the portion of the impeller 2 of the rotating shaft 1, and the quadrupling shaft. This is an impeller with a ring 6 at the connection part before being impregnated with metal. Figure 3 shows the solution for impregnating the metal before impregnation with the metal.
Hot metal containing 9)<8 is shown. The holding fitting 7 is made of cast iron.

Further, the link 6 is made of dense ceramink.

A mold (not shown) in the shape of the impeller 2 is prepared, and the holding fitting 7 is placed in it. , and a firing process to obtain an impeller 2 made of a porous refractory material.

This impeller 2 is immersed in molten metal 9 under predetermined conditions.

The ring 6 fixes the connecting portion of the rotating shaft 1 in order to stop the rotating shaft 1 from idling. Further, the ring 6 is provided to protect the rotating shaft 1 from the molten metal.

Manufacturing Example 2 Referring to FIG. 4 (i), FIG. 4 shows an impeller 10 made of a large metal-impregnated material having a rotary shaft hole 11 into which the rotary shaft 1 can be inserted. In addition, 12
is the part to be welded.

Prepare in advance a metal-containing BmJ firework having a rotary shaft screw hole]1 into which the rotating shaft is inserted. This rotation φdt 1
Insert the rotating shaft 1 into the air manhole 11 and weld the point 2 to stop the rotating shaft from idling.

Manufacture Example 3 An impeller 13 having a body 14 and wings 15 attached to the ends. The main body 14 of the impeller 13 is a porous refractory material, and the wing portions 15 are a metal-impregnated refractory material.

When manufacturing a refractory porous body, the blade part of the impeller 13]
The porosity of the central portion 14 is increased, and the porosity of the central portion 14 is decreased.

That is, the wing portion] 5 is impregnated with metal, but the center portion 14 is impregnated with metal.
Do not impregnate.

This refractory porous body is impregnated with metal, and is particularly worn in J and 1fJi.
An impeller 13 is obtained in which only the blade portions that are easily subjected to metal impregnation are made of refractory.

The approximate dimensions of each part of the impeller manufactured by the above manufacturing method are shown below.

Diameter of impeller rotating shaft: 150 mm Outer diameter of impeller blade: 900 +n+n Thickness of impeller blade: 200 mm Length of impeller blade: 1B00 mm or less, the above various impellers are coated with metal-impregnated refractories of the following quality. The antagonists used and tested are explained below.

Example 1 Production of refractory impregnated with magnesia metal Magnesia powder containing % by weight of MgO was used as a refractory raw material. The particle size of the magnesia powder is 50 to 2000 microns and is made of 9N.

The raw material powders are mixed, a binder is added, and the mixture is stirred for 4'l'. The slurry mixture is poured into a predetermined mold and subjected to vibration molding. This molded body was fired at a temperature of about 1300°C to obtain an impeller made of a porous magnesia refractory body with an apparent porosity of 10 to 53% by volume and an average pore diameter of 60 microns.

This impeller was impregnated with 5US304 under predetermined conditions to obtain a metal-impregnated refractory impeller of Macnaire quality with a 5LIS304 content of d4< of 15 to 7 υ volume IA%. moreover,
UJ machining the surface to create the desired shape.

Using the above method, we investigated the characteristics of metal-impregnated refractory impellers obtained by adjusting the amount of fiber.II! The results are shown below.

Is the spalling resistance of the above block body perfect? j+L (li'r)～:l 4
The mixture was heated to 00°C and then cooled with water. It was investigated whether the strength of the block body was affected by the temperature difference (ie, thermal shock) caused by this rapid heating and cooling.

In Figure 6, the heating temperature ('C) of the refractory is plotted on the horizontal axis,
It is a graph diagram in which the spalling resistance of a metal-impregnated refractory impeller was investigated, with the strength index of the refractory being plotted on the vertical axis. In this case, the strength index of the refractory is expressed as an index of the bending strength after quenching from each heating temperature when quenching is performed, with respect to the case where the flexural strength of the refractory without quenching treatment is taken as 100, This is an indirect expression of the spalling resistance of refractories. In the figure, white circles, white squares, and black squares represent fireworks.
30.45% by volume of Kandong impregnated with 5IJS304. The black circles are magnesia refractories that are not impregnated with metal. As is clear from the government, there are 5
By impregnating US304, the thermal shock resistance of 1ljJ is significantly higher than that without impregnating 5US304.
I knew I could get it. Also, the inclusion U of 5US3[]4
The more legs, the stronger the strength index I+' (lower or less, 1i
iJ) It was confirmed that A-like sporlinkability was improved.

Abrasion resistance and erosion resistance Figure 7 shows the metal impregnated feet on the horizontal axis, and the immersion resistance of large objects impregnated with metal by slag dissolved in vertical pongee;
It is a graph diagram indirectly investigating the wear resistance and erosion resistance of a magnesia-based metal-impregnated large-sized material impregnated with S304. In this case, the permeation quality index is an index representing the amount of erosion of the specimen relative to the amount of erosion (erosion loss) caused by blast furnace slag of a magnesia refractory with no metal impregnated as 100.

As you can see from the diagram, 5IJS304 includes/3:
It has been found that the desired effect can be achieved even if the amount is too small or too large, and that when the impregnation amount is in the range of 20 to 60 volume fA%, the erosion index can be reduced to less than half. .

Table 1 shows the results of actually using the metallic sound N+IuJ large impeller of the same length as described above in the KR desulfurization method. Table 1 shows the composition of the metal-impregnated heavy-duty material (-tIi position: volume %) and the life of the impeller (unit/hour). In addition, the life of the impeller is the wear and tear of the blades m 100 m
It was decided that the event had ended at m.

1 Example 2 Powder containing 97% by weight of AR20:i was used as a refractory raw material for making an aluminous metal-impregnated refractory impeller. The particle size of the raw material powder is 1 to 2000 microns, J,! J adjustment. Vinyl fibers with a diameter of 1.00 microns were used as a compounding material for controlling the size of the pores of a large porous body.

The raw material powder and fibers are mixed at a volume ratio of 9:] to 6.4, a binder agent is added, and the mixture is stirred and mixed. Pour lIX '9 into the designated P2,
This is press-molded. This molded body is fired at a temperature of about 1550°C, and an impeller made of an alumina refractory porous material with an apparent porosity of 25 to 60% by volume and an average pore diameter of 90 microns is made. 'Also.

This impeller was impregnated with a Gr-AI alloy under predetermined conditions to obtain an alumina metal-impregnated refractory impeller with an impregnation rate of 35 to 80%.

Table 2 shows five cases in which the metal-impregnated refractory impeller of the second embodiment was actually used in the RF desulfurization method. Table 2 shows the composition of the metal-impregnated refractory (!F-[St:2 Yongxian%) and the life of the impeller (unit: II!r).
l! :J) and ta. In addition, it was determined that the life of the impeller ended when the blade portion wore out m 100 m++n.

A schematic diagram showing Table 2, FIGS. 3, 4, and 5 are schematic diagrams of impellers to explain the manufacturing method of each impeller, and FIGS. 6 and 7 are the effects of each example. It is a graph diagram for explaining.

DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Impeller 6... Ring, 7... Holding metal fittings, 8... Hot metal bath, 11
Rotator insertion hole, ]4... Main body, ]5... Wing part.

〔Effect of the invention〕

This invention described above provides anti-spalling,
It is possible to create an impeller with excellent wear resistance and wear resistance, and a long lifespan of ta (M).Thereby, the cost of refractories for the impeller can be significantly reduced.

[Brief explanation of drawings]

Figure 1 is a diagram of an impeller related to an embodiment of this invention, and Figure 2 is a schematic configuration of the RF desulfurization method.

Claims (1)

[Claims] An impeller for stirring molten metal, characterized in that a metal-impregnated refractory obtained by impregnating a porous refractory body with metal at a ratio of 10 to 80% by volume is provided at least in the blade portion.