JPS60186454A - Refractory moldings - 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 The present invention relates to a refractory molded product formed by centrifugal molding.

Conventionally, most refractories such as firebricks have been molded by kneading a refractory material with a small amount of water and compression molding, and the shape has often been a rectangular parallelepiped or a similar shape. In addition, the lining of cylindrical objects such as arch molding was also assembled using trapezoidal moldings. However, with the diversification of demand, there have been an increase in the number of special shapes that require less man-hours for lining and assembly, and the performance of these products has also become more advanced.
Improvements in performance were mainly achieved through the careful selection of materials, and molding techniques were limited to increasing compression force and vacuum pressure molding, and other molding methods such as centrifugal molding were not considered.

As is well known, the centrifugal forming method is widely used for concrete products such as balls and pile humps, and is mainly used to form cylindrical products by hardening with the aqueous phase of cement. By creating a concave-convex pattern on the surface of a concrete product, it can be easily centrifugally formed by devising a formwork, so it has come to be applied to concrete products of various shapes.

The present invention proposes an inorganic binder such as alumina cement, alkali silicate, phosphate, or phenol resin as a binder for self-hardening refractories in place of Portland 9 cement, which is a binder for aggregate in concrete products. At least one type of refractory material made of metal oxides such as alumina, silica, magnesia, zirconia, zircon, and chromium, or carbon compounds and nitrogen compounds, selected from organic binders etc. according to each application and whose particle size is adjusted. In addition, it is centrifugally molded. That is, the refractory molded product according to the present invention has the effect of the above-mentioned self-hardening binder, adjusts the particle size of the aggregate, adds a solvent such as water, and performs centrifugal molding, so that coarse particles with large centrifugal force are moved to the outer periphery. Then, the fine particles and fine powder fill the gaps, and the fine particles and ultrafine powder fill the fine gaps, and air, excess water, and excess fine powder gather on the inner cylinder side. If these excess water and excess fine powder are discharged during centrifugal molding, even if the strength of the self-hardening binder is low, it will maintain its shape and will be able to maintain its shape during processes such as demolding, curing, drying, and firing. They discovered that the material has a strength that prevents it from becoming bent or deformed during transportation. Therefore, when a molded body manufactured by centrifugal molding is subjected to heat treatment such as firing to develop its final strength, the strength of the binder itself is not required so much. However, when alumina cement is used as a binder, hardening occurs through an aqueous phase reaction, so regardless of the curing and drying stages in which hydrates do not decompose, the porosity after dehydration decreases in the temperature range where the crystallization water of alumina cement decomposes. As a result, a dense tissue cannot be obtained. Therefore, in order to make it more dense, we use ultrafine powder with a particle size of 1 micron or less such as fireclay, calcined alumina, chromium oxide, silica flour, etc., and use a dispersing agent (peptizer) and a flocculant ( We devised the use of a material containing a coagulant (coagulant) as a binding material. In this process, fine powder, especially ultrafine powder, is dispersed by the action of a dispersant, and after filling the minute gaps formed by the fine powder and ultrafine powder by centrifugal molding, it is cured in a dense state by the action of a flocculant. Since this molded product hardly generates hydrates, the change in porosity due to differences in processing temperature is very small compared to molded products that generate hydrates, such as alumina cement. It can be said that it is one of the most dense molded products.

As the above-mentioned dispersant, one or a mixture of two or more of alkali metal phosphates, polyphosphates, carbonates, carboxylic acids, humates, etc. is used, and the amount added is 0.0
It is 1 to 0.6% by weight.

As flocculants, those that gradually dissolve in water and require time to ionize, such as calcium hydroxide, sulfate, silicate, aluminate, and calcined magnesia, can be used, and the amount added is 1 ~10% by weight.

Next, a centrifugally formed refractory according to the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view explaining the mechanism of centrifugal molding. Coarse particles of about 2.5 to 10 mm 1, fine particles of about 1.2 to 0.15 mm 2, fine particles of several tens of microns to several microns 3. Ultrafine powder of 1 micron or less 4 of the above-mentioned refractory material are used to form a molded body. Depending on the thickness, add 6 to 12 inches of water to 5
The refractory material kneaded material 7 is mixed with air 6 so as to enclose the bubbles or coarse particles 1, fine particles 2, fine powder 6, and ultrafine powder 4. However, the mixed wire 7 with added dispersant
Most of the air 6 becomes closed cells, and the air 6 surrounding the coarse particles 1, fine particles 2, fine particles 3, and ultrafine particles 4 disappears, and the surface becomes water 5.
It is in a wet state. (1) in Figure 1 shows the formwork 8
(One is an enlarged cross-sectional view. As mentioned above, a considerable amount of air 6 is mixed in.
(2) in Figure 1 is a cross-sectional view when centrifugal molding is started by rotating the formwork 8 (the mark is an enlarged view). Initially, the centrifugal force is about 1 to 2 times the gravitational acceleration I. A centrifugal acceleration of It comes into contact with the frame well.Next, as the rotational speed of the formwork 8 is increased to increase the centrifugal force, the coarse particles 1 with a larger mass gradually come into contact with the formwork 8.
It moves to the side, and air 6 and water 5 are expelled and escape inward. Fine particles 2 fill the gaps between coarse particles 1, and fine particles 3 fill the gaps.
Further, the ultrafine powder 4 fills the gaps. (3) in Figure 1 is
These are cross-sectional views when the centrifugal force is several tens of grams (3 are enlarged views). This excess water 5 and excess ultrafine powder 4, fine powder 6, fine particles 2
(4) in Figure 1 is the one that was removed, and the enlarged view is (4).As described above, even if the strength of the self-hardening bonding material is low, It does not easily cause mold mesh or deformation.Coarse grain 1, fine grain 2, fine powder 6
, the ratio of ultrafine powder 4 and its maximum particle size are determined depending on the minimum thickness of the molded body. The maximum particle size must be at least 1/3 of the minimum thickness, and the larger the maximum particle size, the larger the ratio of coarse particles 1, and the wider the selection range of fine particles 2, fine particles 6, and ultrafine particles 4. Also, the amount of water 5 added becomes more necessary as the particle size of fine powder 6 and fine particles 2 becomes smaller and the blending ratio becomes larger, but by using the above-mentioned dispersant, the amount of water 5 added is reduced. In addition, the smaller the particle size, the smaller the mass, and therefore the smaller the centrifugal force, making it impossible to compact the particles sufficiently. Requires centrifugal acceleration.In general, the gaps between single grains are larger than those between single-sized grains and those between fine and coarse mixed grains, and in the case of single-sized grains, the smaller the grain size, the larger the voids. Therefore, in the present invention, by mixing particles of each particle size from coarse particles 1 to ultra-fine particles 4, and by using activated fire-resistant ultra-fine particles and a dispersant, the interparticle attraction force is reduced. Agglomerated fine powder or ultrafine powder is dispersed and minute gaps are filled by centrifugal force to create a dense structure, which is then solidified in a dense state by the action of a flocculant to form a refractory molded product.

FIG. 2A shows a cylindrical molded body 9 of the refractory molded product according to the present invention.
Fig. 2B is a side view showing the state during centrifugal forming, and Fig. 2B is a cross-sectional view thereof, in which the refractory material mixture 7 is formed into a cylindrical shape in a form 8 by rotating the tire portion 10 of the form 8 and the centrifugal wheel 110. It will be done.

Fig. 6 shows (1) a plan view and (2) a side view of refractory molded products of various shapes, but the shapes are not limited to these and various shapes can be manufactured. obtain. Figure 4 shows a cross section during centrifugal molding, in which the refractory material mixture 7 is fed into the formwork 9 while rotating the formwork 8 to which the refractory molded product 9 has been fitted with a small frame 12 inside. Then, the rotation speed is increased and the centrifugal force is increased to sufficiently compact and form the material.

Next, the results of using the refractory molded product according to the present invention in an actual furnace will be shown.

As Example 1, a cylindrical refractory molded product according to the present invention was used as a protective refractory for a burner of a rotary kiln for firing Portland cement. Figure 5 shows an outline of the NSP type Portland cement manufacturing equipment. The cement raw material is preheated and decarboxylated when passing through an auxiliary furnace (preheater) 13, and then fired in a rotary kiln main body 14. The fired cement clinker is cooled in a cooler 15 and then transferred to a crushing facility. Also, cooler 1
In order to utilize the residual heat from step 6, waste heat gas is transferred to preheater 1.
6, a bleed air duct 17, a settling chamber 18, a secondary duct 19
is attached. Since the tip of the burner 20 is inserted into the rotary kiln 14, the burner 20 is subjected to a thermal load of 15,000 or more, and is also subject to significant damage due to wear caused by dust from the foot S15 and the cooler 16. Conventionally, castable was used as a refractory for burner protection, but the construction method was pouring using a rod-shaped pipe lake, and in order to improve workability, there was a tendency for the amount of cross-conducting moisture to increase, so it was difficult to improve the quality. It was difficult to make it dense, there were many variations, and its service life was short, 2 to 6 months, and it was unstable. When the cylindrical refractory molding according to the present invention was used,
It has become possible to use it continuously for 6 months. Table 1 shows the quality of conventionally used castables and the quality of the molded product of this example. It is also possible to perform centrifugal molding directly on the burner, but in this example, a so-called cassette method was adopted in which a cylindrical refractory molded product is manufactured in advance and set on the burner on site. By adopting the cassette method, it is possible to shorten the construction period and greatly contribute to stabilizing operations.

In Example 2, similar to Example 1, the refractory molding according to the present invention was used as a refractory lining for an air bleed duct 17 of a Portland cement production facility.

The bleed air duct 17 suffers from severe wear due to dust from the cooler 16, and the temperature rises to around 100 mph, so conventionally wear-resistant bricks or high-strength castables have been used, but bricks are resistant to wear and tear from the joints. Castanol had problems with wear resistance and had not achieved satisfactory durability.

The refractory molding according to the present invention was used in a part where conventional wear-resistant bricks had fallen off after 6 months due to wear mainly due to joint wear, and achieved a service life of 2 years.

Table 2 shows the quality of conventional bricks and the quality of the refractory molded product according to this example. Note that the refractory molded product used in Example 2 is a fired product.

As shown in Table 1 and Table 2 above, the refractory molded product according to the present invention is sufficiently degassed, so it is molded more densely than vacuum pressure molding, and the outer peripheral surface in particular is compactly molded, making it more compact than conventional moldings. The physical properties are also high performance. Such a centrifugally formed body having an outer circumferential surface is suitable for use as a protector for a rotary kiln burner, a supply pipe for a material to be fired into a furnace, and the like, where the outer circumferential surface is exposed to high heat. In addition, the centrifugal molded body prepared by removing excess fine powder from the inner cylinder surface as described above is suitable for refractory lining of rotary kilns, lining of cylindrical metal melting furnaces, etc.

[Brief explanation of the drawing]

Figure 1 explains the mechanism of centrifugal molding in the order of steps. (1) is before centrifugal molding, (2) is at low speed, (3) is at high speed, and (4) is during finishing. A cross-sectional view,
(1, (2), (3), (4) are partially enlarged views of each of them. Figure 6 shows (1) a plan view and (2) a plan view of refractory moldings of various shapes.
is shown in a side view, FIG.
The figure is an explanatory diagram of the locations where the refractory material according to the example is used. Explanation of symbols 1...Coarse particles, 2...Fine particles, 6...Fine powder, 4...
Ultrafine powder, 5... Kneading water, 6... Air, 7... Kneaded product, 8... Formwork, 9... Centrifugal molded product, 10... Formwork tire, 11... Centrifuge, 12...Small frame, 16
... Auxiliary firing furnace, 14 ... Rotary kiln main body, 1
5...7 9, 16... Cooler, 17... Bleeding duct, 18... Sedimentation chamber, 19... Secondary duct, 20... Burner patent applicant Mino Ceramics Co., Ltd. Dainichi Concrete Industry Co., Ltd. (4 others) Procedural amendment (method) 3. Relationship with the case of the person making the amendments Applicant Name of address Mino Ceramics Co., Ltd. (1 other person) 4. Agent 5. Date of amendment order May 29, 1980 (shipment date)
Supplement I-Contents of Hokomukai blink Z correction (1) The description in the specification has been corrected as follows. Page Line Original text Correction text 5 16 Figure 1 is Figure 1 (1) to (4) are 5 1
4, and (1) to (4) in Figure 1A are the first
6 5 (1') (1) in Figure 1A 6 8 (2') (2) in Figure 1A 6 20 (6') (3) 7 in Figure 1A 5 (4'
) Figure 1A (4) 14 7 Its (1'), (2) Figure 1A (1),
(2), (3) and (3, (4) and (4)
(1,) and (2+) in Figure 1. (3) and (4) respectively (2) Figure 1 of the drawing has been corrected as shown in the attached drawings Figures 1 and 1A. (3) As shown in the attached sheet. Amend the power of attorney.

Claims (1)

[Claims] The aggregate is made of at least one type of refractory material consisting of particle size-adjusted metal oxides such as alumina, silica, magnesia, zircon, zirconia, and chromium, or carbon compounds and nitrogen compounds, and is kneaded by adding water or other solvents. By pouring it into a formwork assembled into a cylindrical shape, etc., and rotating the formwork, the centrifugal force applied to the injected material deaerates and dehydrates it, and the aggregate of each particle size in the injected material is assembled. A refractory molded product formed by combining and compacting, demolding, curing, and drying, and a refractory molded product obtained by firing the refractory molded product.