JPS5827223B2 - Manufacturing method of sintered body - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a sintered body.

Traditionally, when producing alumina from bauxite using the Bayer process, "red mud" has been discharged as almost the only solid by-product.

The emission amount is 0.5 to 0.8 tons of dry red mud per ton of alumina (A1203), which is about 1 million to 1.5 million tons/year in Japan, and in the past it was used as artificial lightweight aggregate. Various methods have been considered for using the waste, but currently the only options available are land reclamation, ocean dumping, and accumulation in red mud.

It is conceivable to use red mud as a sintered body, but a sintered body made of only red mud would have a very large shrinkage, making it impossible to put it into practical use.

It has been proposed to add silica stone as an aggregate to prevent shrinkage, but microcracks are induced by the α-β transition of silica stone, making it impractical.

Therefore, there is a demand for an effective method of using the red mud.

In addition, slags such as granulated blast furnace slag, slowly cooled blast furnace slag, and converter slag are produced by the steel industry, and these slags are used as roadbed materials,
It is used as raw material for cement, fertilizer, etc., but the amount is 6.
It is currently around 0% and is not fully utilized.

Therefore, there is a demand for effective ways to utilize slag such as granulated blast furnace slag, slowly cooled blast furnace slag, and converter slag.

As a result of intensive research in order to meet the above-mentioned needs, the present inventors found that the red clay has a particle size small enough to cause shrinkage during firing (10 to 30μ when dried), has a predetermined particle size distribution, and contains a large amount of coarse particles. It was discovered that when slags such as granulated blast furnace slag, slowly cooled blast furnace slag, and converter slag are used in combination, they compensate for each other's shortcomings, and the present invention was achieved based on this finding.

The purpose of the present invention is to use red mud from industrial waste, which has conventionally had little utility value and has had various problems in disposal, in place of clay that has been conventionally used to form sintered bodies such as tiles and roof tiles. and industrial waste granulated blast furnace slag, slowly cooled blast furnace slag,
It is an object of the present invention to provide a method for producing a sintered body that can easily and reliably produce a useful sintered body from slag from converter slag.

The present invention will be explained in detail below.

First, 10 to 80 parts by weight of red mud, preferably 30 to 60 parts by weight, and 20 to 90 parts by weight, preferably 20 to 90 parts by weight of slag such as granulated blast furnace slag, slowly cooled blast furnace slag, converter slag, or a mixture thereof having a predetermined particle size. 40 to 70 parts by weight are mixed wet or dry.

The red mud used in the present invention is, for example, red mud that is produced as a by-product when producing alumina from bauxite by the Bayer process, and its chemical composition and mineral composition are as shown in Table 1 below, for example. .

As is clear from Table 1 above, the main component is F e2 C
! 3, Az2C)s, Sr02, and the particle size when dry is 10 to 30μ, and when mixed with slag, red mud forms a slag (aggregate) mal-IJ flux and acts as a binder. do.

In addition, granulated blast furnace slag used in the present invention, slowly cooled blast furnace slag,
Slag such as converter slag is a by-product from the steel industry. For example, the chemical composition of granulated blast furnace slag and converter slag is as follows:
As shown in the table.

The present invention is characterized in that of such by-product slag from the steel industry, a portion having a particle size of 5 mm or less and mainly having a particle size of 1 to 5 mm is mainly used as aggregate. do.

That is, if a portion of the slag used has a particle size of 5mm or more, or if the proportion of the particle size of 1mm or less increases even if the particle size is 5mm or less, various problems will occur.

In other words, if a part of the slag used has a particle size of 5 ms or more, the reactivity between the slag particle surface and red mud will decrease,
This is because, during sintering, the sub and the red mud are not integrated, leading to significant shrinkage and the unfavorable reality that sufficient practical strength cannot be obtained.

Furthermore, since the thickness of roof tiles, tiles, etc. is generally between 10 and 25 mm, the maximum allowable particle size is also substantially limited to about 5 mm.

On the other hand, even if the particle size of the slag used is 5 mm or less, if the proportion of the particle size of 1 mm or less is large, the surface of the slag will melt for a short time during sintering, and the slag This is because the undesirable phenomenon that air bubbles remain inside the particles and expand becomes noticeable.

In this way, in the present invention, it is necessary to pay sufficient attention to the particle size of the slag used, but advantageously, it is not necessary to pay so much attention to the by-product slag from the ordinary steel industry. .

That is, the object of the present invention can be remotely achieved by simply adjusting the particle size by removing the portion having a particle size of 5 mm or more.

By-product slag from the steel industry, which has been subjected to such simple particle size adjustment, contains multiple particles with a particle size between 1 and 5, and when mixed with red mud, it becomes densely packed and becomes difficult to sinter during sintering. Shrinkage can also be prevented and does not cause any practical problems.

Furthermore, in the present invention, 10 to 80 parts by weight of red mud and slag such as blast furnace slag, slow-cooled blast furnace slag or converter slag, whose particle size has been adjusted as described above, or a mixture thereof, 20 to 9 parts by weight.
It is also characterized in that it is used in combination with 0 parts by weight.

In other words, if the red mud is 80 parts by weight or more and the slag is 20 parts by weight or less, the particle size of the red mud when dried is extremely small, 10 to 30 μm, which is undesirable because shrinkage during sintering increases rapidly. This phenomenon becomes noticeable, resulting in the inconvenience that the product does not fit within the allowable range of dimensions.

In addition, if the red mud is less than 10 parts by weight and the slag is more than 90 parts by weight, there is not enough red mud to form the 7-trix of the aggregate (slag), so the sufficient effect as a binder is not exhibited, and the practical strength is The unfavorable phenomenon that not only is not obtained, but also that the water absorption rate becomes high becomes noticeable.

Furthermore, in the present invention, when mixing the red mud and slag, powders of practical glasses such as silicate glass such as soda lime glass, phosphate glass, and borate glass, kaolinite clay, etc. Plastic clay, alkali compounds such as K2O and Na2O, fluorine compounds such as fluorite, boric acid,
Up to 20 parts by weight of a boron compound such as borax or a mixture thereof may be blended.

These compounds act as fluxes to promote sintering, are low-sintering components that lower the melting point, and are characterized by lowering the sintering temperature and making the sintering process more economical. When plastic clay is used as a flux, the plasticity in the subsequent molding process is obtained not only from the red mud but also from the clay, resulting in very good plasticity and making it possible to perform the subsequent molding process efficiently. become able to.

Next, the mixture obtained as described above is compression molded or extruded, and then heated and dried at room temperature for about 24 hours.

After that, using a sintering device such as an electric furnace,
Sinter at a sintering temperature of 0°C.

When sintered at a sintering temperature within this range, a sintered body with virtually no shrinkage or cracks can be obtained. However, at temperatures below 500°C, sintering will not be sufficient, and at temperatures above 1300°C, microcracks will occur. This may cause inconveniences such as intrusion.

By sintering at 500 to 1300°C as described above, the sintered body using red mud and slag can be reliably prevented from shrinking and cracking.

Slag has alternating hydraulic properties, which may pose a problem with long-term weathering, but this is also due to the reaction between iron and slag during sintering, creating a glassy substance of iron oxide solid solution that is structurally stable. The surface is covered and weathering from the surface can be prevented.

Further, the unreacted slag remaining in the sintered body changes from a glassy substance to a crystalline substance (melilite) during the sintering-cooling process, and the latent hydraulic property is lost and stabilized.

As described above, the sintered body obtained by the method of the present invention has excellent properties with virtually no shrinkage or cracks, and therefore can be used for various purposes such as roof tiles, tiles, ceramic blocks, and bricks.

Particularly in the case of roof tiles, if a sufficient sintered body is obtained that can serve as a base material, and a glaze is applied to the surface of the sintered body, a roof tile with practical strength can be obtained.

Generally, roof tiles and tiles have a thickness of 10 to 25 mm, and it is known that the particle size of the aggregate has a wide range of particle sizes or is suitable to be 5 mm or less. The slag used as the material fully satisfies this requirement, and the sintered body formed by the method of the present invention is excellent as roof tiles.

As explained above, the present invention has a particle size of 571 trIL or less in 10 to 80 parts by weight of red mud, and mainly 1 to 5 trIL.
Slag, such as granulated blast furnace slag, slowly cooled blast furnace slag or converter slag, or a mixture thereof, which has a particle size of 20 mm and whose particle size is adjusted so that it is densely packed when mixed with the red mud.
90 parts by weight and 20 parts by weight or less of a glass powder, a plastic clay alkali compound, a fluorine compound, a boron compound, or a mixture thereof as a flux per 100 parts by weight of the total amount of red mud and slag, and the mixture is compressed or extruded. After molding and drying, 500-13
It is configured to sinter at 00°C.

Therefore, according to the present invention, a state in which red mud with a small particle size (10 to 30 microns when dry) and a particle size of 571 Lm or less, and mainly having a particle size between 1 and 5, is mixed with the red mud. By using the slag in combination with the slag whose particle size has been adjusted so that it is densely packed, the defects of each other can be compensated for and eliminated, and a sintered body without shrinkage or cracks can be easily and reliably formed.

That is, an extremely significant industrial effect is achieved in that a useful, high-quality sintered body can be easily formed from red mud and slag, which are industrial wastes.

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples.

The amount of flux in Examples 1 to 8 and Comparative Examples 1-A to 3 below is the amount per 100 parts by weight of the total amount of red mud and slag, and unless otherwise specified, slag was obtained from the steel industry. A portion of the by-product slag with a particle size of 5 mrft or less was used.

Example 1 Dry weight (D, W.

) Red mud containing 40φ of moisture 6709 45weightφ (D
, wJ400.9) Granulated blast furnace slag 500g 55 //Plastic clay 100g 11 After wet kneading the three raw materials, put it in a tile mold and mix it at 70kg/i.
compression molded.

Next, it was dried by heating at 100°C for 1 day, and then fired at 1100°C for 4 hours in an electric furnace.

The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 2φ Weight 30kg (1mX1mX16n tiles) Bending breaking strength 120kg/cy? i Water absorption rate 16 Comparative example 1-A Processed in the same manner as in Example 1, but the granulated blast furnace slag used in this comparative example was the part of by-product slag from the steel industry with a particle size of 5 or more. did.

The physical properties of the obtained sintered material (tile) are as follows.

Shrinkage rate: 5.8 Weight (1mX1mX16m7Ico tile) 31kg
Bending fracture strength 621y/cr? L water absorption rate 23% Comparative Example 1-B The granulated blast furnace slag used in this comparative example was treated in the same manner as in Example 1, but only the part of the by-product slag from the steel industry with a particle size of 1 mm or less was used. used.

The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate (expansion rate) -4.2% weight (1mX
1m x 16m tiles) 29kg bending breaking strength
57kg/cI? L water absorption rate
21% The physical properties of the sintered bodies (tiles) obtained in Comparative Examples 1-A and 1-B are significantly different from those of the sintered bodies (tiles) obtained in Example 1.

That is, the particle size of the granulated blast furnace slag used is 571Lr/
If it is more than L, the shrinkage rate becomes very large and the bending fracture strength also decreases significantly.

On the other hand, when the particle size of the granulated blast furnace slag used is less than 1 inch, the shrinkage rate becomes negative, that is, it expands, and the bending fracture strength also decreases significantly.

The water absorption rate tends to increase in both cases.

Furthermore, such changes in physical properties between sintered bodies are observed not only when granulated blast furnace slag is used, but also when slags such as slowly cooled blast furnace slag, converter slag, or mixtures thereof are used. It will be done.

As described above, in the present invention, it is necessary to pay sufficient attention to the particle size of the slag used, and it is recommended to use a portion having a particle size of 5 mm or less, and mainly a particle size of 1 to 5 m7IL. is necessary.

However, advantageously, slag with such a particle size structure can be obtained by simply adjusting the particle size by removing the part of the by-product slag from the regular steel industry that has a particle size of 5 mm or more. It will be done.

Example 2 D.W.

Red mud containing 40% moisture 1170g 78 weight φ (D,
W, about 700 g) Granulated blast furnace slag 200 g 22 weight φ plastic viscosity 100 g After wet mixing three raw materials of 11 weight ratio, the same treatment as in Example 1 was carried out.

The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 2.3φ Weight (1mX1mX16i gong tile) 30ky bending breaking strength 98ky/ffl Water absorption rate
20% Comparative Example 2 D, W.

Red mud containing 40% moisture 1250g 83 weight φ (D
, W, 75og) Granulated blast furnace slag 150g 17wt Plastic clay 100.9wt 11wt After wet mixing three raw materials were treated in the same manner as in Example 1.

The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 9.3% Weight (1mXl door x 16n tiles) 33-bending breaking strength 72kg/i Water absorption rate
Section 24 As can be seen by comparing the physical curve properties of the sintered bodies (tiles) obtained in Examples 1 and 2 with those of the sintered bodies (tiles) obtained in Comparative Example 2, 80 parts by weight of red mud As mentioned above, when the slag is 20 parts by weight or less, the shrinkage during sintering increases rapidly.

In other words, the dimensions of the product do not fall within the allowable range.

Such changes in the physical properties of the sintered body (tile) occur not only when granulated blast furnace slag is used, but also when using slags such as slowly cooled blast furnace slag, converter slag, or a mixture of these. is also accepted.

Example 3 D, W.

Red mud containing 40% water 170g 111 parts by weight D
, W, 102 g) Granulated blast furnace slag 800 g 899 parts by weight Plastic clay 100 g 111 parts by weight The three raw materials were wet mixed and treated in the same manner as in Example 1.

The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 1.7 factor Weight (lmX1mX16mtrU) tile) 28kg
Bending fracture strength 95ky/i Water absorption rate
Section 19 Comparative Example 3 D, W.

Red mud containing 40% water 100. @7 parts by weight (
D, W, 60 g) Granulated blast furnace slag 840 g 933 parts by weight Plastic clay 100 g 111 parts by weight The three raw materials were wet mixed and treated in the same manner as in Example 1.

The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 2.3φ Weight (lmX1mX16rmrV) tile) 27 to 9
Bending fracture strength 62kp/cr? L water absorption rate 38φ As can be seen by comparing the physical properties of the sintered bodies (tiles) obtained in Examples 1 and 3 with those of the sintered bodies (tiles) obtained in Comparative Example 3, red Mud 10 parts by weight or less Slag 90
If the amount exceeds the weight part, the aggregate (slag) Mat-I
Since there is not enough red mud to form J Lux, sufficient effect as a binder is not exhibited, and bending fracture strength is significantly reduced, making it impossible to obtain practical strength.

In addition, the water absorption rate also becomes extremely high, making it impractical for practical use.

Such changes in the physical properties of sintered bodies (tiles) occur not only when granulated blast furnace slag is used, but also when slags such as slowly cooled blast furnace slag, converter slag, etc., or a mixture thereof are used. is also accepted.

Example 4 A tile was made in the same manner as in Example 1, except that converter slag was used instead of granulated blast furnace slag, and the following conditions were used.

D, W.

Red mud 500g (D, W, 300g) 333 parts by weight Converter slag 600g 67 / Plastic clay 100g 11.

Firing temperature: 1150'C The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 1.8 multi-weight (1mX1mX17m tile) 38ky bending breaking strength
115kg/i water absorption rate
18φ As is clear from this example, the slag that can be used in the present invention is not limited to granulated blast furnace slag.

Converter slag can also be used. In addition to these slags, slowly cooled blast furnace slag can also be used, and mixtures thereof can also be used.

Example 5 A tile was made in the same manner as in Example 1, except that fluorite (OaF2) was used as the flux and the following conditions were used.

D.W.

Red mud 670g (D, W, approx. 455 parts by weight 400) Granulated blast furnace slag 500g 55 /Plastic clay 100g 11 // Fluorite 20,9 2n Firing temperature 10500C Obtained sintered body (
The physical properties of the tiles are as follows.

Shrinkage rate 2.5φ Weight (1mX 1mX 16mv OD tile) 32 to 9 bending Breaking strength 125kg 7cyyt Water absorption rate
14 Bun Example 6 A tile was made in the same manner as in Example 1, except that borax (Na2B107 .10)40) was used as a flux and the following conditions were used.

D.W.

Red mud 670. ! 7 (D, W, approx. 400.@)
45 weight steamed blast furnace granulated slag 500g55// Plastic clay 100.9 11. /borax 50.9 55//firing temperature 900°C The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 2.3 fb type weight 1r
rL x 1m x 1611L gong tile) 35kg bending breaking strength 118kg/ffl water absorption rate
16 Example 7 A tile was made using the same process as in Example 1, but using soda lime glass powder as the flux and using the following conditions.

D, W. Red mud 590g 35 weight (
D, W, approx. 350.9) Converter slag 670g 65, /Plastic viscosity 50g 49 //Soda lime glass powder 30g 3p Firing temperature
The physical properties of the sintered body (tile) obtained at 850°C are as follows.

Shrinkage rate 1.5 Weight (1mX1mX17mm SD tile) 28kg Bending breaking strength 142ky/c7? l Water Absorption Rate Section 13 Example 8 A tile was made in the same manner as in Example 1, except that clay containing a large amount of alkali was used and the following conditions were used.

D.W.

Red mud 340,9 22 weight superior (
D, W, approx. 200g) Granulated blast furnace slag 650g 78, / Ano Yuri (K20+Na20) 150,9
Clay containing 18,/45% Firing temperature: 950°C The physical properties of the obtained sintered body (tile) are as follows.

Shrinkage rate 0.8 Bun weight (1mX1mX15m tile) 30kg Bending breaking strength 128kg/i Water absorption rate
1707b As is clear from Examples 4 to 8, in the present invention, not only plastic clay but also fluorite, borax, practical glass powder, and alkali compounds can be used as a flux for promoting sintering when red mud and slag are mixed. , or a mixture thereof may be blended.

As described above in detail based on the examples, the present invention has 10 to 80 parts by weight of red mud, a particle size of 5 cm or less, and mainly has a particle size of 1 to 57 nrrL. Mixing with 20 to 90 parts by weight of slag such as granulated blast furnace slag, slow-cooled slag, or converter slag, or a mixture thereof, whose particle size has been adjusted so as to be densely packed when mixed with mud; 20 parts by weight or less of glass powder, plastic clay, alkali compounds, fluorine compounds, boron compounds, or mixtures thereof are mixed as a flux per ioo parts by weight of the total amount of red mud and slag, and the mixture is compressed or extruded. After drying, 500-1300
The present invention relates to a method for producing a sintered body characterized by sintering at °C.

Claims (1)

[Claims] 1 having 10 to 80 parts by weight of red mud and a particle size of 5 degrees or less,
and slags such as granulated blast furnace slag, slow-cooled blast furnace slag, or converter slag, which mainly have a particle size of 1 to 5 mm and whose particle size is adjusted so as to be densely packed when mixed with the red mud, or slags thereof. While mixing 20 to 90 parts by weight of the mixture,
Per 100 parts by weight of the total amount of red mud and slag, glass powder, plastic clay, alkali compound,
A method for producing a sintered body, which comprises mixing 20 parts by weight or less of a fluorine compound, a boron compound, or a mixture thereof, compressing or extruding the mixture, drying it, and then sintering it at 500 to 1300°C. .