JPS5924161B2 - Manufacturing method of blast furnace fine sand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves blast furnace slag, which is a by-product from blast furnaces during pig iron production, into hard water slag, and converts it into hard water slag according to the construction work standard specifications
The present invention relates to a method for producing blast furnace fine sand corresponding to SS5 fine aggregate grade 1.

Blast furnace slag is generated from blast furnaces, which accounts for approximately 35% of the pig iron production, and the method for processing it is to collect the slag in a slag steel car, transport it to the slag field, and then gently drain the slag from the slag pot ( field method) and
There is a dry pit method in which a pit is created around the furnace and the slag is poured into the pit.

In either case, after the molten slag has cooled, it is excavated using a bulldozer or shovel dozer, and crushed and sieved at a sizing factory or the like to produce aggregates (ballast).

The products produced by this kind of treatment are collectively called slow-cooled slag (or slow-cooled slag), and this processing power method requires a vast area, and in places where the slag field is narrow, it is necessary to cool the slag quickly. Water is being sprinkled for this reason.

However, due to the heat held by the slag, the sulfur content in the slag reacts with water to generate H2S, or during the cooling process of the slag, the sulfur content is oxidized to generate SO2, which is unfavorable in terms of the working environment.

Another method for treating slag is to rapidly cool it with water and turn it into blast furnace water slag (
There is also a water cooling method called quenched slag.

There are two methods: a furnace front method in which the slag is rapidly cooled directly from the trough, and a ladle method in which the slag is poured into a steel car before the furnace and transported to another location for rapid water cooling.

When a large amount of cooling water is injected into the hot slag, the slag becomes granular, about the size of sand grains.

The appearance of the slag is that when the slag is rapidly cooled with water, some of the jetted water enters the slag and turns into water vapor, rapidly expanding, and the slag becomes pumice-like.

When this is dehydrated, it becomes a normal water slag with a moisture content of 15 to 25%.

Compared to the field method or dry pit method of slowly cooling slag processing, this water cooling method requires a smaller processing area.

■Less environmental pollution.

■ Due to rapid water cooling, it has a lot of glassy content and is rich in latent hydraulic properties.

■Since it becomes sand grains, there are many advantages such as no need for sizing equipment.

In addition to the above treatments, there are methods to cool the slag with an appropriate amount of water, or mechanically turn it into fine particles, cool and foam them, and adjust the particle size to make expanded slag, but these methods have not yet been put to practical use in Japan. .

As mentioned above, there are several methods for treating blast furnace slag, and each steelworks adopts the most appropriate method depending on its locational conditions and disposal method, but in most cases, slowly cooled slag is used.

Only 7% of people used water slag in the 1975 calendar year.
Due to the advantages mentioned above, the use of water cooling systems with water slag is being reconsidered.

When blast furnace slag is rapidly cooled with water, the amount of glass is 98-99%, and this glass exhibits latent hydraulic properties, so it can be used as a raw material for cement such as blast furnace cement, high sulfate slag cement, acid-resistant cement, expansion cement, seawater cement, Used in oil well cement, etc.

A wide range of other uses are being developed, including ground stabilization treatment, sludge treatment, heavy metal waste treatment, Conc IJ-1 products, and fertilizers.

Recently, residents have become more demanding regarding conservation of the natural environment and pollution, and restrictions have been placed on the collection of natural aggregates, making it increasingly difficult to obtain aggregates.

On the other hand, there is an annual demand for approximately 300 million tons of coarse aggregate and approximately 200 million tons of fine aggregate, and if something suitable for this purpose were developed, an extremely large amount of blast furnace slag would be consumed. .

However, the demand for ordinary water slag mentioned above is expected to increase due to its properties and shape, but as a fine aggregate, it has weak strength due to its porous production method so far, and in this case, natural sand It has the disadvantage that it cannot be used as a substitute.

In order to overcome this drawback, the present invention modifies the blast furnace slag to form hard water slag with dense plaster and coarse grains, which is then crushed to meet the stipulated construction standard specifications. Book J
We invented a series of processes to create artificial sand that passes ASS5 Fine Aggregate Grade 1.

The present invention relates to a method for manufacturing hard water slag (Japanese Patent Application No. 50-96791 filed by the present applicant) and an apparatus for manufacturing hard water slag (Japanese Patent Application No. 50-96791 filed by the present applicant).
1-20669), this is a new blast furnace fine sand manufacturing system that uses an impact crusher especially for particle size adjustment.

In this method, the molten slag is reformed in front of the blast furnace, resulting in glassy 95%
This system is characterized by producing large coarse particles with a latent hydraulic hardness of more than 10%, and adjusting the particle size using an impact crusher. If a problem occurs or if H2S gas or SO2 is
It has great features such as it does not generate gas, has a low pH during the elution test, and can be easily handled like natural sand.

In order to obtain the continuous particle size required by JASS5 fine aggregate grade 1 by crushing hard water slag with a moisture content of 5 to 15%, we conducted crushing tests using various crushers and found that an impact crusher was suitable.

A continuous particle size cannot be obtained with a roller mill, and 0 and 6 grains are crushed with a rod mill and a ball mill due to the moisture resistance of the water dregs.
There is a drawback that powders of 1 mm or less agglomerate together and form ball-shaped lumps, resulting in unbalanced continuous particle size, which is an essential condition for fine aggregate.

That is, it is necessary to sieve this powder mass, and in some cases, it is also necessary to dry this powder mass, re-crush it, remix it, adjust the particle size, and make it into a standard product.

An impact crusher uses a rapidly rotating impact rod (or plate) to apply intense impact and centrifugal force to the raw material, causing it to collide with a fixed rod or other impact plate to crush the material with a powerful instantaneous force. This is a crusher with an extremely wide range of applications.
It is a pulverizer that has few breakdowns, is easy to maintain, can obtain a predetermined continuous particle size of crushed products in one pass, and has low initial and running costs, making it most suitable for pulverizing hard water slag.

Impact pulverizers are broadly classified into the incinerator type and the hammer mill type, and either type can be used, but the hammer mill type is especially often used for crushing crushed stone, and is designed to prevent powder from adhering to the pulverizer. The model that takes this into account shows the best results.

When installing a discharge chute at the bottom of the crusher, pay attention to the shape and inclination of the chute to prevent powder lumps from sticking to the discharge chute, and use pie breaks to constantly vibrate during crushing to prevent the growth of powder. It is necessary to take measures such as

Note that although an impact crusher is suitable for this purpose as described above, other types of crushers can also be used if their characteristics are considered.

Based on the above, it should be noted that there is no problem in using a type of crusher other than an impact crusher as the crusher used in the crushing process of this system, and the system is a series of systems including this point.

The present invention will be described in detail with reference to FIG. 1 shown in the drawings.
The slag discharged from the blast furnace 1 through the slag trough 2 is directly in front of the furnace by a cooling rotating body 3 having a large number of protrusions or fins on its surface and equipped with a heat exchange ability, a high-speed water injection mechanism, and The slag flows down and spreads on the surface of the rotating body 3 of the hard water slag production device 5 equipped with a chute 4, and the molten slag is 13 in the hard water slag production device 5.
Rapidly cool down to below 00°C and adjust the temperature.

This molten slag, whose temperature has been adjusted to below 1300° C., is injected into a water tank 6 with high-speed water jet and rapidly cooled with water to form hard, dense, coarse particles.

If the water tank 6 is a sedimentation tank, the large coarse particles are drained by draining water from the bottom rosdol, or if it is a stirring tank, the coarse particles are sent to the dehydration tank 7 with water using a slurry pump for dewatering. .

The cooling water used is fresh water that is circulated through a circulating water tank 14.

When the water temperature is 80 to 90°C or higher, it is desirable to use a cooling tower 8 for cooling.

The coarse grains dehydrated as described above have a coarse particle ratio of approximately 30 to 4.5, which is considerably higher than the 25 to 3.5 of ordinary water scales, and the unit volume weight is 1.10 to 1.50, which is 0. Significantly heavier and harder than .5 to 1.10.

Observation using a stereomicroscope and an X-ray diffraction device reveals that hard water slag is completely amorphous (vitreous) lumpy glass with some small bubbles, whereas normal water slag is completely amorphous. It has been found that the difference is due to the fact that it is a foam glass containing numerous bubbles.

It is thought that the difference in unit volume weight was caused by this bubble content.

The dehydrated coarse grains contain 5 to 15% water, and the dehydrated coarse grains are directly fed from the water tank 6 or the dehydration tank 7 via the supply hopper 9 to the supply feeder (for example, a roll feeder, etc.) 10. A fixed amount is cut out and supplied to an impact crusher 11 for crushing.

The crushed products are stored in the shipping tank 12 or shipping yard 12', and are further homogenized by draining water and or-betting.
Use blast furnace fine sand with a particle size equivalent to ASS5 fine aggregate grade 1.

To transport large coarse particles and crushed products, a packet crane 13, a belt conveyor 13', a packet conveyor 1r, etc. shall be installed singly or in combination, taking into consideration the equipment and layout of the T field.

In addition, it is also possible to adjust the crushing particle size according to the demands of the customer to produce fine aggregates of various particle sizes (for example, fine aggregate or coarse aggregate).

The hard water slag crushed product, which is the blast furnace fine sand obtained by the method of the present invention as described above, and the JA
The comparative measurement results with SS5 fine aggregate 1st grade were as shown in Table 1 below.

Fig. 2 shows a comparison between this crushed product and the JASS 5 Fine Aggregate Class 1 and JASS 5 Fine Aggregate Class ■ in the Construction Standard Specifications based on the test results in Table 1 above.

In addition, the comparative measurement results of the PH values and elution tests of conventional slowly cooled crushed sand, extraction method water slag, furnace front method water slag, and natural hard water slag after being left indoors for 1 month are shown in Table 2 below. It was on the street.

As shown in Table 1 and Figure 2, the blast furnace fine sand of the present invention produced as described above corresponds to JASS5 fine aggregate class 1 in the construction standard specification, and its composition is 95% or more glassy. As shown in Table 2, there is no environmental pollution even in the elution test.

This method of producing fine blast furnace sand is characterized by the furnace front method.
Of course, the ladle method can also be used.

However, in this case, depending on the cooling state of the molten slag in the ladle, the glass content may be less than 95%.

27.3 million tons of blast furnace slag was generated in the 1975 calendar year, of which 62% was used for ballast, but some of the ballast is simply used for reclamation and land development. According to the method for producing fine blast furnace sand of the present invention, it is possible to supply artificial sand of a certain quality at a low cost, which has a high added value and is comparable to natural sand, which is becoming a scarce resource. This is an economical and highly beneficial way to utilize resources.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of an apparatus for carrying out the method of the present invention, with solid line arrows indicating the main process of producing fine blast furnace sand, and dotted line arrows indicating sub-processes. FIG. 2 is a chart showing a comparison between the hard water slag crushed product obtained by this method and the JASS5 fine aggregate 1 fine aggregate 1 rough range of construction work standard specifications. 5...Hard water slag manufacturing device, 6...Water tank, 7...Dehydration tank, 11...Impact crusher, 12... Shipping tank, 12'...Shipping yard.

Claims (1)

[Claims] 1. The first step is to adjust the temperature of the molten slag discharged from the blast furnace in front of the furnace, and the temperature-adjusted slag is rapidly cooled with water to form hard, dense, coarse particles with a glass content of 95% or more. or a stirring tank), and a second step in which the water content of the coarse particles is reduced to 5 to 15% by removing water in the sedimentation tank or by transferring the slurry to a dehydration tank using a slurry pump. 3 steps, a 4th step in which the dehydrated coarse particles that have been drained of water after the completion of the 3rd step are crushed with an impact crusher to adjust the particle size, and the crushed products are stored in a shipping tank or shipping yard for water removal and oring. A method for producing fine blast furnace sand characterized by the fifth step of homogenizing in a sanding process.