JP2000319708A - Production of blast furnace slag fine aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce fine aggregate for concrete and mortar at a low cost in a large quantity with simple equipment by using water-granulated slag rapidly cooled with water as the raw material. SOLUTION: Classification and crushing are applied to the granular blast furnace slag which is rapidly cooled by using the water, to improve the grain diameter distribution and grain shape. The producing method is: the water- granulated blast furnace slag is crushed after classifying otherwise, the water granulated blast furnace slag is classified after crushing. Then, it is desirable to separately crush each of ones obtd. on plus sieve and minus sieve and mix them, after classifying the water-granulated blast furnace slag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention crushes granular solid slag produced by quenching with water when discharged from a blast furnace to produce fine aggregate used for concrete, mortar and the like. It is about the method.

[0002]

2. Description of the Related Art There are two methods for treating slag discharged from a blast furnace: a method in which slag is flown in a molten state through a yard or a dry pit, and a method in which the slag is gradually cooled. There is a method of cooling with water and rapid cooling. Among them, the blast furnace slag produced by the water-cooling method is a vitreous solid slag having a particle diameter of 5 mm or less, called granulated slag. This granulated slag is finely crushed and used as a blast furnace cement raw material.
Lightly crushed, it is also used as a raw material for civil engineering construction instead of natural sand. Among the uses for civil engineering and construction, there is a fine aggregate used for concrete, mortar, and the like, and hereinafter referred to as a slag fine aggregate. In particular, in recent years, there has also been a problem of environmental destruction caused by sea sand extraction regulations and land sand development, and demand for slag fine aggregate as an important recycled material for preserving natural resources has been increasing.

Slag fine aggregate is required to have different physical properties from granulated slag used as fine powder for blast furnace cement raw materials, and as specified in JIS A5011, has a relatively large specific gravity and water absorption. Granulated slag with low rate. For example, as in the method described in Japanese Patent Application Laid-Open No. 55-136151, the cooling method is also different from that for the blast furnace cement raw material, and is produced under relatively strong cooling conditions. By improving such a cooling method, it is possible to produce a granulated slag having a large absolute dry specific gravity and a large unit volume mass and easily applicable to fine aggregate. However, in order to create a sufficiently strong cooling condition to satisfy the performance as a slag fine aggregate without cooling the product slag after cooling, the amount of cooling water becomes excessive, and equipment costs such as pumps increase. There was a problem that the service cost was high.

[0004] In addition, unprocessed granulated slag produced by cooling, hereinafter referred to as raw ore granulated slag, contains fine needle-like vitrified slag mixed with granular slag. . Because the needle-shaped slag is mixed, the granulated slag particles have a characteristic that it is difficult to be in a densely packed state. As a result, the space occupancy of the slag particles,
Refers to the actual rate, but is low.
Even in the physical property range defined by S, good performance was not necessarily exhibited as fine aggregate.

[0005] In other words, from the knowledge of conventional civil engineering, if the performance rate of fine aggregate is generally low, the fluidity of ready-mixed concrete deteriorates, and when concrete is pumped during construction,
Problems such as clogging of the pump and deterioration of the surface properties of the finish are recognized because concrete does not turn to the corners of the formwork. Since there is a similar phenomenon in slag fine aggregate, it was important to produce a granulated slag fine aggregate with a high achievement rate.

Accordingly, as a method of increasing the achievement rate, for example, as described in Japanese Patent Application Laid-Open No. 53-22522, crushed raw ore slag is conventionally crushed using a crusher such as an impact crusher. That is being done. In other words, by lightly crushing the raw ore granulated slag, it is possible to reduce the particle size, destroy the acicular slag, improve the performance rate and unit mass, and improve the performance as fine aggregate. Have been done.

[0007] It is also important to make the particle size distribution of the granulated slag appropriate for the fine aggregate by the crushing operation. In other words, reducing the particle size of the ore granulated slag and widening the particle size distribution, and setting the appropriate ratio from fine to coarse to improve the fluidity of ready-mixed concrete and mortar It is also important that the particle size be improved by a crushing operation.

[0008]

As described above, in order to improve the performance as fine aggregate, it is effective to lightly crush raw granulated slag using a crusher. But,
Granulated slag with a large particle size of 1 mm to 5 mm has a surface that is uneven, but has a shape relatively close to a sphere,
Needle-like slag is mixed in the granulated slag having a particle size of 1 mm or less. At the stage of the ore, the needle-like slag easily enters between relatively large granular slags, and as a result, the performance rate of the ore granulated slag was low, and dense fine aggregate could not be obtained.

[0009] In addition, in order to improve the performance of the granulated slag as a fine aggregate, the ore granulated slag has been conventionally crushed. However, in the conventional method, only crushing is required. There was only an idea, and the effect of improving the performance as a sufficient fine aggregate was not raised. In other words, even when crushing ore slag, the fact that needle-like slag is dispersed between relatively large granular slags is an obstacle to the production of fine aggregate even when crushing ore slag. Had become.
In other words, in the case of crushing raw ore granulated slag as it is with a conventional crusher, the acicular slag enters between the granular slag having a large particle size, and the acicular slag effectively becomes a crushing surface of the crusher. Since there is no contact, there is a problem that the shape of the needle-shaped slag is difficult to break. Therefore, in the conventional crushing method, even in the crushed granulated slag, needle-shaped slag remains, and the packing density becomes low. The performance as fine aggregate did not improve sufficiently.

In order to make up for this drawback of the conventional method, if the degree of crushing of the raw ore granulated slag is increased, the shape of the acicular slag is destroyed, and the actual rate of the granulated slag is sufficiently improved. The particle size of the slag became too small, and the coarse particles having a diameter of 2 to 5 mm, which affect the compatibility with the coarse aggregate, were insufficient, and the result was also insufficient in terms of the flowability of the ready-mixed concrete. . Therefore, even in the case of the crushing method in which the crushing process is performed sufficiently and the particle size is considerably reduced, it has been difficult to secure the performance of the granulated slag as fine aggregate.

[0011] As described above, the granulated slag fine aggregate produced by the conventional method has insufficient performance to ensure the fluidity of the ready-mixed concrete. Problems such as easy clogging of the pump and problems such as an increase in the amount of cement and water used to secure the fluidity of the ready-mixed concrete and an increase in concrete production costs have occurred.

[0012]

Means for Solving the Problems The present invention provides the following (1):
To (5). (1) A method for producing blast furnace slag fine aggregate, characterized by improving the particle size distribution and particle shape by subjecting blast furnace slag in the form of granulated powder quenched with water to classification and crushing. (2) The method for producing blast furnace slag fine aggregate according to claim 1, wherein the granulated blast furnace slag quenched with water is crushed after classification. (3) The method for producing blast furnace slag fine aggregate according to claim 1, wherein the granulated blast furnace slag quenched with water is classified after crushing. (4) The granulated blast furnace slag quenched by using water is classified, and then the blast furnace slag obtained above and below the sieve is crushed, and these are mixed and mixed. Aggregate manufacturing method. (5) The method for producing blast furnace slag fine aggregate according to (1) to (4), wherein the crushed and granular blast furnace slag is classified with the classification point of 0.3 mm to 1.2 mm.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of equipment for carrying out the granulated slag crushing method of the present invention. This figure shows an apparatus for performing classification after crushing. The raw ore granulated slag in the raw ore granulated slag supply hopper 1 is supplied to the crusher 3 by the belt conveyor 2, where the raw ore granulated slag is lightly crushed. The lightly crushed granulated slag is sent to the classification device 4 and divided into upper and lower sieves. The granulated slag on the sieve is collected in the granulated slag hopper 5 as slag fine aggregate. At this time, the average particle size of the granulated slag on the sieve at the time of classification is from 1.2 mm to 2 mm.
It is desirable to classify so as to obtain mm. The crusher 3 and the classifier 4 are adjusted as slag fine aggregate. In particular,
Considering the sieve efficiency, the classification point of the classification device 4 is 0.3 mm
It is desirable to adjust the height to 1.2 mm.

The fine aggregate recovered on the sieve after the classification has a high performance rate and a high absolute dry specific gravity because most of the needle-like slag contained in the portion having a small particle diameter is removed.
Good fine aggregate can be manufactured.

FIG. 2 shows another example of equipment for implementing the granulated slag crushing method of the present invention. The ore granulated slag in the ore granulated slag supply hopper 1 is transferred to the belt conveyor 2.
Then, it is sent to the classification device 4 and divided into upper and lower sieves. Each granulated slag is supplied to a crusher 3, where it is lightly crushed. The slag after each light crushing is collected in the product granulation hopper 5. If necessary, the lightly crushed granulated slag is mixed in the mixing device 6. At this time, the classification point at which the mixing of needle-like ones with those close to the large spheres in the granulated slag is 0.3 mm to 1.2 mm. Depending on the cooling method of the granulated slag, the state of the particle size distribution of the acicular slag changes.Therefore, within the range of the classification point described above, several sieves are prepared. Select and install and classify. This figure shows an apparatus that performs crushing after performing classification. In some cases, it is equipment that can mix the granulated slag after each crushing.

[0016]

EXAMPLE The average particle size of the granulated slag collected from the raw ore granulated slag 1 shown in Table 1 after being lightly crushed by the equipment shown in FIG. , Actual rate, and unit volume mass are shown in Table 2 as Example 1. The crushing was performed with an impact crusher, but a crusher of another type such as a rod mill may be used. Table 2 also shows the slump test results indicating the flow characteristics of the ready-mixed concrete. In the slump test, a ready-mixed concrete was prepared and mixed under a condition in which the slump was 15 cm using a good natural fine aggregate conforming to JIS, and the slump test was performed. When the performance of the fine aggregate deteriorates, the fluidity deteriorates and the slump value decreases. The properties of the ore granulated slag are as shown in Table 1.

[0017]

[Table 1]

[0018]

[Table 2]

In Example 1, the average particle size was 1.7 mm, which was slightly larger than that of the comparative example, but was in an appropriate range as a fine aggregate. The performance rate was as high as 57%, and the unit volume mass was as high as 1.55 kg / l. As a result, the performance as fine aggregate was good, the slump was 14.5 cm, and the fluidity as ready-mixed concrete using this slag fine aggregate was sufficient.

Further, as Example 2, Table 2 also shows the test results of fine aggregate of slag obtained by classifying raw granulated slag 2 shown in Table 1 with the same equipment at 0.4 mm.

In Example 2, the average particle size was 1.6 mm, which was equivalent to that of the comparative example. However, the actual rate was as high as 56%, and the mass per unit volume was as high as 1.52 kg / l. As a result, the slump was 14.0 cm, and the fluidity as ready-mixed concrete using the slag fine aggregate of this example was sufficient.

The granulated raw ore slag 1 shown in Table 1 was classified with a 1.0 mm sieve using the equipment shown in FIG. 2, and the upper and lower sides of the sieve were lightly crushed. Example 3
As shown. Here, crushing was also performed using an impact crusher. The average particle size of this slag fine aggregate is
It was 1.55 mm, which was in an appropriate range as fine aggregate. The performance rate was as high as 58%, and the unit volume mass was as high as 1.59 kg / l. As a result, the slump was 15.5 cm, and it was found that the fluidity as ready-mixed concrete was completely equivalent to that of a good natural fine aggregate.

The raw ore granulated slag 2 shown in Table 1 was classified with a 0.4 mm sieve using the same equipment, and the granulated slag on the sieve obtained by slightly crushing the upper and lower sides of the sieve was evaluated as fine aggregate. The results are shown in Table 2 as Example 4. The average particle size of the granulated slag was 1.45 mm, which was in an appropriate range as fine aggregate.
The achievement rate is as high as 57%, and the unit mass is 1.52 kg.
/ L. As a result, the slump was 14.5 cm, and it was found that good fluidity as ready-mixed concrete was secured.

As described above, it is desirable to change the classification point of the classifying device in accordance with the change in the properties of the raw ore granulated slag. It is effective to set the range to 1.2 mm.

However, the granulated slag fine aggregate produced by the conventional method could not sufficiently exhibit the performance as an aggregate. The result of manufacture of granulated slag fine aggregate by the conventional method is shown. The result of performing only light crushing of the raw ore granulated slag 1 by the conventional method is shown as Comparative Example 1 in Table 2. In Comparative Example 1, the average particle size was 1.
5mm, which is in the appropriate range as fine aggregate, but the actual rate is 5
It was as low as 3%, and the unit mass was relatively low as 1.45 kg / l. As a result, it was found that the performance as fine aggregate was not sufficient, the slump was only 12.5 cm, and the fluidity as ready-mixed concrete was low.

Next, in order to investigate the influence of the classification point at the time of classification, a test result with a large sieve and a test result with a small sieve are shown. The test production was performed using the equipment shown in FIG. 2, and the raw ore granulated slag 1 shown in Table 1 was used as a comparative example.

Table 2 shows the results of the test operation when the classification point of the sieve was 1.3 mm after crushing.
The actual rate and unit mass were good, but the average particle size was
Due to being too large as 2.1 mm, fine particles important for lubrication are lacking, fluidity in ready-mixed concrete is poor, slump is 12.5 cm, and fine aggregate as fine aggregate It turned out that the performance was not satisfactory enough.

As an example in which the classification point of the sieve is 0.3 mm or less, an example in which the classification is performed with a 0.25 mm sieve is shown in Comparative Example 3. The average particle size is too small at 1.1 mm. Due to the lack of coarse granulated slag and insufficient removal of needle-shaped granulated slag, the slump was still 12.0 cm due to the lack of achievement rate. It turned out that the performance as was not satisfactory. For the above reasons, the classification point of the classification device according to the present invention is set to 0.3 mm to 1.2 mm.

Further, in Comparative Examples 4a and 4b of Table 2, the slag fine aggregate obtained by merely sieving using a 0.7 mm sieve without crushing the raw ore granulated slag 1 was also evaluated. The results are shown. The measured values of the granulated slag after classification show the results of the granulated slag on the sieve in Comparative Example 4a.
Although the value was as good as 8 mm, the actual rate was as low as 50% and the unit mass was as low as 1.27 kg / l. As a result, the slump value was as small as 10.5 cm, indicating that it was a poor fine aggregate. Comparative Example 4b shows the results of granulated slag under a sieve.
mm, the performance rate was as low as 49%, and the unit volume mass was as low as 1.22 kg / l. As a result, the slump value was as small as 10.0 cm, which was also found to be poor fine aggregate.

When the finely divided granulated slag aggregate that had just been classified was examined with an optical microscope, a large amount of needle-like vitrified slag was present, which was the reason that the performance rate did not increase. There was found. Thus, by applying only classification to the granulated slag, a high-quality granulated slag fine aggregate could not be produced.

As described above, as a result of producing a slag fine aggregate using the present invention, a slag fine aggregate suitable for ready-mixed concrete can be economically produced. In addition, since fine aggregates for mortar are required to have good fluidity as well as concrete, the present invention is similarly effective for manufacturing slag fine aggregates for mortar.

[0032]

According to the present invention, fine aggregates for concrete and mortar can be manufactured inexpensively and in large quantities with simple equipment using granulated slag quenched with water as a raw material.
In addition, by performing the crushing and classification, it is possible to correct the change in the properties of the ore granulated slag due to the change in the cooling method at the time of producing the granulated slag, and to produce an appropriate fine aggregate.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a crushing and classifying apparatus for granulated slag of the present invention.

FIG. 2 is a view showing another embodiment of the crushing and classifying apparatus for granulated slag of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw crushed slag supply popper 2 Belt conveyor 3 Crusher 4 Classifier 5 Product granulated slag hopper 6 Mixing device

Continued on the front page (72) Inventor Yuji Toda 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Works F-term (reference) 4K012 AA02

Claims (5)

[Claims] 1. A method for producing blast-furnace slag fine aggregate, comprising classifying and crushing granular blast-furnace slag quenched with water. 2. The method for producing blast furnace slag fine aggregate according to claim 1, wherein the granulated blast furnace slag quenched with water is classified and then crushed. 3. The method for producing blast furnace slag fine aggregate according to claim 1, wherein the granulated blast furnace slag quenched with water is classified after crushing. 4. The method according to claim 2, wherein the granulated blast furnace slag quenched with water is classified, and then the slag obtained above and below the sieve is crushed and mixed. Production method of blast furnace slag fine aggregate. 5. The method for producing a blast furnace slag fine aggregate according to claim 1, wherein the classification is performed using a classification point of 0.3 mm to 1.2 mm.