JPH0645486B2 - Modified steel slag cement and method for producing the same - Google Patents

Description

The present invention relates to a modified steel slag cement and a method for producing the same.

[Prior Art] It is well known that steelmaking slag has a basic composition of basic calcium silicate, and that its powder has latent hydraulicity, like blast furnace slag.

However, ordinary steelmaking slag is not used as a cement material because its hydraulic speed is slow.

Slowly cooled slag is crushed and used as a ballast,
It has been said that it cannot be effectively used as much as blast furnace slag due to a pulverization phenomenon (generally called dandruff phenomenon) due to volume expansion accompanying compositional transformation.

Regarding the use of steelmaking slag for cement, there is a proposal that the slag composition is adjusted and specified to be a cement having good hydraulic property (for example, Japanese Patent Publication No. 57-34223).

As another method, a large number of methods have been proposed in which gypsum and calcium chloride, slaked lime or the like as an alkali stimulant are mixed with steelmaking slag to accelerate hydraulic properties.

It is also known to add gypsum, calcium chloride or the like to a modified steelmaking slag itself, which is similar to the above method.

[Problems to be Solved by the Invention] Conventionally, the use of steelmaking slag as a cement material often requires the addition of gypsum and an alkali stimulant in addition to the slag, and compared with Portland cement. It is not characteristic and in many cases the performance is poor.

In the case of modifying steelmaking slag into steel slag cement itself, it is difficult to control the composition, and there is a problem that slag of a specific composition cannot always be prepared. The strength and other performances are not exceptional or characteristic.

An object of the present invention is to improve the latent hydraulic properties of steelmaking slag to provide a high quality steel slag cement.

[Means for Solving Problems] In view of the problems as described above, the present invention has a performance higher than Portland cement as a steelmaking slag cement, or
As a result of earnest research to impart a characteristic performance that the cement does not have, the present invention has been completed by finding that characteristic hydraulic properties can be exhibited when a small amount of alkali and boron components are present in the molten steelmaking slag.

Therefore, according to the present invention, the basicity (CaO / SiO ₂ ) is 1.3.
In the steelmaking slag powder of Nos. 5 to 5, the alkali metal component as R ₂ O (wherein R represents Li, K or Na) is 0.05 to 3 wt% and the boron component is 0.1 to ₂ as B ₂ O _{3 based on the} total weight.
5 wt% and has a Blaine specific surface area of 15
It is an object of the present invention to provide a modified steel slag cement characterized by having a hydraulic property in the range of 0 to 8000 cm ² / g.

Further, the present invention provides a method for producing a modified steel slag cement, which comprises adding a substance containing an alkali metal component and a boron component to a steelmaking slag melt, followed by cooling and crushing.

[Operation] In the present invention, the steelmaking slag is a by-product whose main ingredient is calcium silicate produced as a by-product during steel refining, and is not particularly limited. For example, ordinary steel slag, special steel slag, electric furnace Examples thereof include steel slag and slag for pre-washing treatment. In most cases, the basicity CaO / SiO ₂ is in the range of 1.3 to 5, preferably 1.5 to 4, and the other components are generally ₂ to 25% by weight of Al ₂ O ₃ and 5 of MgO.
˜15% by weight. For example, stainless slag and nickel slag are typical.

In the cement according to the present invention, it is important that the slag powder contains the alkali metal and boron components in the above range. Here, the content does not mean that the slag powder is simply mixed with the alkali metal and boron components, but the mixture of the slag and the alkali metal component and the boron component is heat-treated to modify the slag. It is usually a powder obtained by adding the liquid component to the slag melt and cooling it as described later.

Although the modified steel slag cement in the present invention is a slag powder as described above, the powder may be either a crystalline powder which is a slowly cooled product of the steelmaking slag or a glassy powder which is a rapidly cooled product by water granulation. Absent.

It should be noted that the particle size of the powder should be able to change depending on the application and method of use of the modified steel slag cement according to the present invention, and in many cases it is not uniform but the Blaine specific surface area value is 1500.
It is in the range of up to 8000 cm ² / g.

Next, in the case of industrially producing the modified steel slag cement according to the present invention, it is characterized by adding a content of alkali and boron to the steelmaking slag melt and cooling and pulverizing by a conventional method. To do.

Examples of the alkaline agent include alkali metals such as lithium, potassium and sodium. Generally, slaked lime, quicklime or calcium component such as calcium chloride, which is a typical alkali stimulant, is included in the definition of the alkaline agent of the present invention. I can't.

However, there is no denying that these components may be supplementarily contained when used as cement.

Examples of the alkaline agent include hydroxide, carbonate, phosphate, silicate, borate and the like.

On the other hand, examples of the boron agent include natural or synthetic products such as boric acid, sodium borate, calcium borate, urexite, tincal, carnite or colemanite.

As another raw material, glass containing alkali and boron, that is, alkali borosilicate glass can be mentioned as a preferable example.

The glass composition is not particularly limited, but when considering the case where glass is manufactured as a raw material in advance, B ₂ O ₃ : 20 to 50
% By weight, CaO: 10-35% by weight, SiO ₂ : 20-
40 wt% and R ₂ O (wherein R has the same meaning as above): a range of 3 to 15 wt% is preferred.

In addition, alkali silicate glass, glass scraps, and the like are also used as other alkaline agent raw materials.

When such a raw material is added to the steelmaking slag melt, smooth melting into the molten slag may be inferior depending on the mode of addition to the molten slag, and sometimes a non-melted mass, so-called "mamako" may occur.

Therefore, in order to promote good melting, diffusing and mixing effects in the molten slag promptly after the addition of the alkali and boron-containing material, an auxiliary agent can be added if necessary.

Such an auxiliary agent refers to a powder that causes dehydration and / or decarboxylation reaction by heating, and examples of such powder include aluminosilicates such as clays, activated clay and diatomaceous earth, bentonites and zeolites. At least one selected from carbonates such as pearlite, pearlite, limestone, calcium, magnesium or barium
Or two or more species.

The amount of these auxiliaries added is not uniform depending on the type of the slag, the addition method of the alkaline agent, etc., and the physical properties and state of the molten slag.
It may be up to wt%, preferably in the range 5 to 15 wt%.

The amount of the alkaline agent and the boron agent added to the steelmaking slag is R ₂ per total weight in the slag powder obtained after cooling the slag.
It is necessary to set O as 0.05 to 3 wt% and B ₂ O ₃ as 0.1 to 5 wt%.

The reason for this is that outside the above range, practical hydraulic properties cannot be obtained, and even if hydraulic properties are present, excessive damage or economical inconvenience will result.

After adding an alkaline agent or the like to the molten slag, if the time required for uniform dissolution is maintained, gradual cooling according to a conventional method or water granulation rapid cooling or solidification by cooling by a desired means,
It is then crushed into a product.

The product grain size of the modified steel slag cement is not uniform depending on the application etc., but as described above, the Blaine specific surface area value is 1500 to 80.
00 cm ² / g, preferably 2000-6000 cm ²
/ G range.

The slowly cooled product of the steelmaking slag usually undergoes volume expansion due to the crystal transformation of calcium silicate and is powdered, but the slowly cooled product of the present invention is surprisingly stable and does not substantially powder. From this point as well, it can be seen that the steelmaking slag has been modified. Therefore, it goes without saying that this slowly cooled lump slag is finely pulverized as described above and provided for cement, but if necessary, a coarsely crushed product having a desired particle size can be effectively used as an aggregate of the cement. it can.

The modified steel slag cement according to the present invention is a small amount of modifier,
Moreover, hydraulic properties can be easily imparted, and the effect is beyond expectations. Furthermore, the cement according to the present invention has a remarkable heat resistance characteristic.

This can be pointed out as a completely unexpected and surprising effect in comparison with ordinary cements such as Portland cement, which show remarkable strength deterioration when heated and have no heat resistance.

The cement according to the present invention may be used as a cement material itself, but may be used in combination with other cement materials such as Portland cement, alumina cement and blast furnace cement.

Further, it can be used together with other slag, for example, blast furnace slag, and can be effectively used by using gypsum or a known alkali stimulant, an auxiliary additive to cement products, etc., if necessary.

[Examples] Example 1 1) Preparation of modified steel slag cement When stainless steel slag taken out in an electric furnace for steel making (30 ton capacity) was transferred to a ladle and then slag pot was removed therefrom, 5 pieces of 10 kg / bag of borosilicate alkali glass powder were directly added to 3.7 tons of slag.

Then, after cooling, the modified stainless steel slag mass was crushed to a specific surface area of 3400 cm ² / g (Blaine value) to obtain a modified steel slag cement.

It was confirmed that this modified stainless steel slag mass had been left for 3 months, but had completely solidified, and no collapse phenomenon occurred.

The compositions of the steelmaking slag before and after reforming and the borosilicate alkali glass powder used as the modifying agent were as follows.

2) Evaluation i) Evaluation of hydraulic property Based on JIS R-5201-1981 physical test method for cement,
Strength Test Method A modified steel slag cement was filled in a mold for producing a test piece, and immersion curing was performed in water and seawater to observe the hydraulic property. The results are shown in Table 2.

Although the conventional slag containing no borosilicate alkali glass was gradually cooled to the steelmaking slag in the slag pot, the lump gradually collapsed after cooling and eventually completely pulverized. The powder obtained by pulverizing this powder to 3000 cm ² / g showed the same hydraulic properties as those described above, but none of them had hydraulic properties.

ii) Abuse test Regarding the specimen that was taken out after hydraulic hardening for 5 days and left for 3 months (4 × 4 × 16 cm), saturated steam pressure abuse test by autoclave was conducted for 3 hours at each pressure.
The results in the table were obtained.

iii) Heat and flame resistance test A heating test according to JIS A1304, which is a fire resistance test method for building structures, where the structure part is a wall is 100 × 1.
When the test piece of 00 × 20 mm was placed in a propane gas heating furnace under the condition that the surface temperature of the test piece was about 1100 ° C., the results shown in Table 4 were obtained.

The test piece that had undergone the heating test was taken out from the furnace as it was and allowed to cool. However, the development of cracks, cracks, peeling, etc. were not observed at all with the slight minute cracks generated on the surface.

It is generally recognized that the Portland cement molded plate has a heat resistance that is weak and is heated and deteriorates due to strength deterioration. In contrast, the molded product of the modified steel slag cement of the present invention has a surprisingly high heat resistance. It was confirmed to have.

Example 2 With respect to various steelmaking slags shown in Table 5, the modifier shown in Table 6 was added to the slag melt to modify the slag, and then granulated by water granulation or slow cooling. Powders having various specific surface areas shown in Table 6 were obtained.

Regarding each of these powders, the hydraulic properties and the test specimens formed by hydraulic hardening were observed by the same evaluation method as in Example 1. As a result, it was found that the water granulated product had better hydraulic properties than the slowly cooled product. Almost the same results as in Example 1 were obtained.

[Effects of the Invention] The present invention has not been effectively utilized in the past and can be industrially advantageously used as a modified steel slag cement by modifying a steelmaking slag. This cement has surprisingly high heat resistance as compared with conventional ordinary cement, and can be expected to be used as a secondary product.

Further, according to the production method of the present invention, it is possible to easily modify the by-product slag to obtain a cement material in the conventional steelmaking process without requiring new heat energy particularly during cement production. Because it is possible, we can be convinced that its industrial value is enormous.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Kurita 2-25 Matsuki-cho, Koriyama-shi, Fukushima Nippon Chemical Industry Co., Ltd. Koriyama factory (72) Kosuke Takeuchi 2-25 Matsuki-cho, Koriyama-shi, Fukushima Nippon Chemical Industry Co., Ltd. Koriyama Factory (56) Reference JP-A-52-141497 (JP, A) JP-A-61-48461 (JP, A) JP-A-63-79743 (JP, A)

Claims (5)

[Claims] 1. A steelmaking slag powder having a basicity (CaO / SiO ₂ ) of 1.3 to 5 contains R _{2 of an} alkali metal component based on the total weight.
0.05 as O (in the formula, R represents Li, K or Na)
3 wt% and boron component and also contains 0.1 to 5% by weight _B 2 _{O 3,} and Blaine specific surface area of 1500 to
A modified steel slag cement, which is a powder in the range of 8000 cm ² / g and has hydraulic properties. 2. The modified steel slag cement according to claim 1, wherein the steelmaking slag powder is a stainless slag powder. 3. A method for producing a modified steel slag cement, which comprises adding a substance containing an alkali metal component and a boron component to a steelmaking slag melt, followed by cooling and pulverizing. 4. The method for producing a modified steel slag cement according to claim 3, wherein the alkali metal component and the boron-containing substance are alkali borosilicate glass. 5. Alkali borosilicate glass has a chemical composition of B
₂ O ₃ : 20 to 50 wt%, CaO: 15 to 35 wt%, SiO ₂ : 20 to 40 wt%, and R ₂ O: 3 to 15
The method for producing a modified steel slag cement according to claim 4, wherein the content is% by weight (wherein R represents Li, K or Na).