JPS60260483A - Ceramic filter for melt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field The present invention relates to a novel ceramic filter for molten metal.

II and 11. Inclusions in molten metal, such as in tundishes. Conventionally, the method of removing inclusions in molten steel has been the soil separation method, but this method does not completely remove the inclusions. It is. Therefore, recently, a method has been developed in which a tubular or weir-shaped refractory having many through-holes is used as a filter, and the molten metal is passed through the filter to allow the inclusions to adhere to and separate from the inner surfaces of the refractory holes. 58-148058@, Japanese Patent Application Laid-open No. 58-176064, etc.),
This method has the following drawbacks. That is, since the surface to which inclusions adhere is limited to the inner surface of the through-hole, the removal efficiency is low because the specific surface area of the surface to which they adhere per unit volume of molten metal is small, and there are disadvantages such as low strength because of the large number of through-holes. be.

As a result of intensive research aimed at developing ceramic filters free from the above-mentioned drawbacks, the present inventors have discovered a rod-shaped or (and) string-shaped molded body containing a refractory raw material and a binder, or a coating material using this molded body. The sintered body coated with S has many voids, so the specific surface area of the adhesion surface is large, the removal efficiency of inclusions in the hot water is high, and the sintered body has sufficiently high strength. Therefore, the present inventors have discovered that this type of filter is extremely suitable, and have completed the present invention.

Shell W Lid 1 The present invention provides a rod-shaped or (and) string-shaped molded body containing a refractory raw material and a binder and having a cross-sectional diameter of 0.3 to iQg+m, which is formed irregularly or (and) regularly. A ceramic filter for molten metal characterized by being sintered and integrated into a ceramic filter, and a rod-shaped or (and) string containing a refractory raw material and a binder and having a cross-sectional diameter of 0.3 to 1QllI. A ceramic filter for molten metal, characterized in that it is a shaped body, the surface of which is coated with a coating material, which are arranged irregularly or (and) regularly and then sintered and integrated. It depends.

The ceramic filter of the present invention is formed by sintering the specific rod-shaped or (and) string-shaped molded bodies (which may be coated with a coating material) arranged irregularly or (and) regularly. It has a large number of voids in its structure, and has sufficiently high strength. Here, sintering of rod-shaped or (and) string-shaped molded bodies arranged irregularly or (and) regularly means, for example, (1) having a constant or various shapes (length, cross-sectional shape); (2) A layer in which rod-shaped molded bodies of a certain shape are irregularly entangled and sintered, or (2) a layer in which rod-shaped molded bodies of a certain shape are irregularly entangled and the shape is different from that. One or more layers in which a rod-shaped molded body of a certain shape is irregularly intertwined are sintered by overlapping alternately or continuously or discontinuously in the order of the shape (e.g. length) of the rod-shaped molded body. (3) Even if layers of rod-shaped molded bodies of a fixed or various shapes are arranged in a fixed direction and layers arranged in a different direction (for example, at right angles) are alternately overlapped and sintered. (4) A rod-shaped molded body of a fixed or various shapes and a string-shaped molded body of a fixed or various shapes may be irregularly intertwined and sintered; (5) A fixed or (6) String-like molded bodies of various shapes may be folded irregularly or regularly and sintered; (6) String-like molded bodies of fixed or various shapes may be folded irregularly or regularly. This shows that layers in which the rod-shaped bodies of fixed or various shapes are irregularly intertwined or regularly arranged may be alternately overlapped and sintered.

The ceramic filter of the present invention is manufactured, for example, as follows.

That is, a refractory raw material, a binder, water, etc. are kneaded and extruded into a rod or string using an extruder or the like. The rod-shaped molded body may be obtained by appropriately cutting a string-shaped molded body base material or a product obtained by drying or calcining the same, or may be obtained by cutting a regular molded body into a rod shape. Moreover, the rod-shaped or string-shaped molded body may have its surface coated with a coating material described later, and by using this, the strength of the molded body itself is improved after firing, and the bonding strength between the molded bodies is also improved. This further increases the strength of the resulting ceramic filter.

The cross section of the rod-shaped molded body or string-shaped molded body may be any shape such as circular, oval, square, rectangular, polygonal, etc., and may be solid or hollow, but the diameter thereof is about 0.3 to 10t+i. It is better to Note that the diameter in the present invention is of course the diameter when the cross section is circular, but when the cross section is not circular, the diameter is determined by the following formula, but the structure of the ceramic filter tends to become dense and the voids tend to decrease. If the length exceeds 101 m, the structure of the ceramic filter after firing tends to be sparse (") and the strength tends to decrease, which is not preferable.

Further, the rod-shaped molded body or string-shaped molded body may be linear or curved, or may be twisted.

Rod-shaped and string-shaped are originally continuous concepts, so in the present invention, the length of the rod-shaped molded product is not limited at all, but for convenience of handling, the length is usually 3 to 3.
It is often set to about 500111.

The refractory raw material used above is not particularly limited and may be acidic, neutral, or basic, such as alumina, mullite, clay shale, zircon, zirconia,
Spinel, magnesia, clay, dolomite, silica, chamotte, chromium, lime, etc. can be mentioned, and one or more of these can be used in combination to meet the required usage conditions (e.g. temperature of the molten metal, reaction with the molten metal). properties, required strength, etc.). Carbon, silicon carbide, nitride, etc. may be used in combination as a refractory raw material. These refractory raw materials are used after appropriately adjusting the particle size according to a conventional method.

In addition, the binder is not particularly limited, and examples include organic binders such as methylcellulose 1, polyvinyl alcohol, dextrin, sodium ligninsulfonate, pitch, tar, and resin, sodium silicate, potassium silicate,
Examples include inorganic materials such as aluminum phosphate and magnesium phosphate, and at least one of these is used.

The above-mentioned refractory raw material and binder are kneaded according to a conventional method, with addition of hydrating water as necessary, and then formed into a rod or string as described above.

Next, the obtained rod-shaped molded body or (and) string-shaped molded body,
Fill the raw material into a molding frame made of refractory material or the like after drying or calcining it. 'Furthermore, if it is desired to further increase the strength of the ceramic filter, the surface of the obtained rod-shaped molded body or (and) string-shaped molded body or dried or calcined material is coated with a coating material.

The coating material in the present invention includes at least one of metal powder, inorganic material, and organic material, depending on its properties.
Used as a powder, solution or suspension. In the above, metals include, for example, AQ 1St, l
``e, C, r, CuSTi, etc.'' In addition to the various refractory raw materials mentioned above, inorganic materials include, for example, alumina, silica,
Alumina sol, silica sol, alumina cement, bittern,
Silicates such as sodium silicate and potassium silicate, aluminum phosphate 1. Examples of the organic material include phosphates such as magnesium phosphate, sodium birophosphate, sodium hexametaphosphate, and mu, and examples of the organic material include pitch, tar, lignin sulfone H soda, and phenol resin.

When the coating material is used in powder form, the particle size is not particularly limited and may be determined as appropriate. In addition, examples of solvents used when making the coating material into a solution or suspension include water, alcohols, petroleum ether, butyl acetate, toluene, glycerin, triheromethane, glycol, etc. One type or a mixture of two or more types may be used. The concentration of the solution or suspension may be determined as appropriate depending on the nature of the solute or suspended component and the coating method.

The two methods of coating a rod-shaped or string-shaped molded body with the coating material are not particularly limited, but may be carried out in any arbitrary manner, for example. That is, when coating a rod-shaped or string-shaped molded body base, it is usually coated by appropriately adhering a powder coating material, or by dipping, spraying, etc. with a solution or suspension coating material. Good. In addition, when coating a dried or calcined rod-shaped or strand-shaped molded article, it is usually coated with a coating material in the form of a solution or suspension by dipping, spraying, etc.
Just cover it up.

In the above, when a coating material in the form of a solution or suspension is used, 1. After coating, drying or calcining is usually performed as appropriate. Further, when a powder coating material is coated on a substrate, it may be left as is or may be dried or calcined as appropriate. Also,
The coating may be applied once, or may be applied multiple times as necessary. In addition, the amount of coating is not particularly limited, and is determined as appropriate depending on the type of coating material, the required strength of the ceramic filter, etc. That's fine.

Next, the coated bar or bar is coated as described above.

(Fill the string-shaped Seijin body into a molding frame made of refractory material, etc.)

In the above, when filling the molding frame with the rod-shaped molded bodies and/or string-shaped molded bodies (or coated molded bodies), they are arranged irregularly or (and) regularly. At this time, if necessary, vibration may be applied, or it may be pressed with an appropriate pressure after filling. Further, the firing may be performed while the mold is filled in the mold, or the mold may be removed from the mold.

Firing is usually carried out at about 1000 to 2000'C, preferably 1
It is carried out at a temperature of 350 to 190°C, which results in a sintered, integrated ceramic filter.

The firing temperature should take into account the composition of the raw materials used and the various properties required for the ceramic filter after firing, such as strength, and should be stable so that there is no change in quality or shrinkage of the structure during use as a ceramic filter. Therefore, within the above range, select a temperature that is approximately equal to or higher than the operating temperature. The firing time may also be determined as appropriate. Also,
The molding frame used above can be of any shape, for example rectangular parallelepiped (including plate-shaped), cube, prismatic, cylindrical, cylindrical, spherical, etc., or a combination of these. Ceramic filters with irregular shapes or with through holes can be manufactured depending on the purpose of use. Further, the through holes can also be provided by processing after firing.

The ceramic filter of the present invention uses refractory raw materials,
The strength of the product can be improved by selecting and combining various lengths, cross-sectional shapes and diameters, presence or absence of coating, arrangement method, firing temperature, presence or absence of through holes, etc. of the rod-shaped compacts and/or string-shaped compacts. The porosity, that is, the specific surface area of the adhesion surface, the maximum operating temperature, etc. can be adjusted as appropriate depending on the purpose of use. It is preferable that the porosity is usually about 40 to 90%.

The ceramic filter of the present invention has a novel structure not previously known, can be used at a high temperature, has sufficiently high strength, and has a large specific surface area, so it is efficient in removing inclusions in molten metal. . Therefore, when using the ceramic filter of the present invention, not only can extremely high durability be obtained compared to conventional filters of this type, but also inclusions can be almost completely removed, reducing the defective rate of castings etc. can be significantly reduced.

Next, the usage mode of the ceramic filter of the present invention will be illustrated. FIGS. 1 and 2 are cross-sectional views showing an example in which the ceramic filter of the present invention is used to remove inclusions from molten steel in a tundish. Figure 1 shows Tanditshu (1)
This is an example in which the ceramic filter (3) of the present invention is attached to the inner weir (2). FIG. 2 shows the ceramic filter (3) of the present invention attached around the upper part of the nozzle (4) in the tundish (1).

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A particle-sized refractory raw material consisting of 97 parts by weight of chamotte containing 71% by weight of alumina and 29% by weight of silica and 3 parts by weight of kaolin clay was kneaded with 30 parts by weight of a liquid binder (15% by weight aqueous solution of methyl cellulose). Then, using an extrusion molding machine, the cross section is circular with a diameter of 2 cm and the length is 10 ~
A 1201 m long rod-shaped compact was mixed with 70 parts by weight of ultrafine alumina powder with a particle size of 5 μm or less and 30 parts by weight of ultrafine silica powder with a particle size of 1 μm or less.
A rod-shaped molded body was obtained by placing the powder in a container containing the mixed powder with parts by weight and having its surface coated with the above-mentioned powder. This was assembled on a baking cart to form a molding frame (46 pieces made of high alumina bricks).
0x460x250 (-1)) and fired in a tunnel kiln at a maximum temperature of 1600°C for 6 hours, the individual coated rod-shaped molded bodies were irregularly intertwined and sintered to form a lightweight body with many voids. A ceramic filter with sufficient strength was obtained. The porosity of this is 58%
Met. Furthermore, through holes with a diameter of 1011 were provided at intervals of about 3°.

When I installed this as shown in Figure 1 and used it, it was extremely ^^
It showed excellent durability, and the defective rate of the obtained castings was significantly reduced.

Example 2 The surface of the base of a rod-shaped molded body with the same composition as in Example 1 and a diameter of 21 mm was coated with a 60% bittern solution by spraying, and this was assembled into a molding frame (high alumina Combined bricks: outer diameter 350 x inner diameter 200 x length 700
(Im)) and fired in a tunnel kiln at a maximum temperature of 160.0°C for 6 hours. In this way, as in Example 1, a ceramic filter was obtained in which the rod-shaped compacts were irregularly entangled and sintered into one piece. The porosity of this is 6
It was 2%.

When this was installed and used as shown in Figure 2, Example 1
obtained similar results.

[Brief explanation of the drawing]

Figure Wi1 and Figure M2 are cross-sectional views showing examples in which the ceramic filter of the present invention is used to remove inclusions from molten steel in a tundish, respectively. The symbols in the figure indicate the following. DESCRIPTION OF SYMBOLS 1... Tanditshu, 2... Weir, 3... Ceramic filter of this invention, 4... Nozzle. (That's all) Figure 1 Figure 2

Claims (1)

[Claims] ■ Rod-shaped or (and) string-shaped molded bodies containing a refractory raw material and a binder and having a cross-sectional diameter of 0.3 to 1011 are arranged irregularly or (and) regularly. A ceramic filter for molten metal characterized by being arranged, sintered, and integrated. ■ A rod-shaped or (and) string-shaped molded article containing a refractory raw material and a binder and having a cross-sectional diameter of 0.3 to 10 mm, the surface of which is covered with a coating material. 1. A ceramic filter for molten metal, characterized in that it is arranged irregularly or (and) regularly and sintered and integrated.