JPS582179B2 - Method for producing blast furnace slag containing crystalline materials - Google Patents

Description

[Detailed Description of the Invention] The present invention uses molten blast furnace slag (hereinafter referred to as slag) as a raw material to produce slag with a quality suitable as a substitute for natural sand used in various construction and civil engineering fields. The present invention relates to a method for producing water slag, which is particularly useful as a fine aggregate for concrete.

In the previously filed Japanese Patent Application No. 48-133751 (Japanese Unexamined Patent Publication No. 50-84629), the present inventors proposed that instead of the conventional blast furnace water slag composed of glass, crystalline and vitreous slag was used. We have completed the production of a new high-quality mixed water slag.

This new slag has a double structure consisting of a crystalline interior and a glassy outer periphery, so it has superior quality such as strength, specific gravity, and water absorption rate compared to the old slag, and is also easier to adjust particle shape and particle size. When applied as a fine aggregate for concrete, it has remarkable improvements in workability, breathing, etc., and can produce high-strength concrete at low cost and with good workability. It has tremendous advantages.

Tables 1 and 2 show examples of various physical properties and mortar test results of both slags, and the differences between the two are clear from the tables.

Now, in the invention of the earlier application, as a manufacturing method for obtaining this new water slag, the method involves controlling the temperature of the slag in the treatment of molten blast furnace slag and the process of turning it into water slag, that is, the temperature of the slag at 1400° C.
A method was proposed and disclosed in which the high-temperature slag is gradually cooled down to a temperature of around 1,300°C, and then high-pressure water is jetted and collided with the slag to rapidly cool and crush the slag, as in the conventional method.

Although this force method can relatively easily produce a water slag with a target crystal content, it still has the following problems.

(1) A certain slow cooling time (1 to 2
time), which increases manufacturing time.

(2) Therefore, in the case of the so-called pot method, in which the slag is received in a pot and then transported from the front of the furnace to a distant slag site to be turned into slag, a certain amount of annealing time can be secured, but the slag is collected directly in front of the furnace. The furnace-front method, which is becoming more popular, has disadvantages such as increasing the number of pots and reducing the work space, so it cannot be said to be an appropriate method.

(3) The viscosity of the slag increases with slow cooling, which may impair workability and deteriorate the quality of the slag.

The present invention has been made with the aim of solving the above-mentioned problems of the prior invention. Specifically, the slag is stirred to promote crystal growth, and then the slag is rapidly cooled to form a water slag. It is characterized by

The present invention will be described in detail below, focusing on experimental examples conducted by the inventors.

Figure 1 shows 200g of blast furnace slag (chemical composition〈%〉MgO2~
7, Al2O3 16-19, SiO230-34, K
2O0.1~0.4, CaO38~44TiO2 1~
3, MnO0.6-1.2, FeO0.2-0.5, S
0.8 to 1.9) in a carbon crucible (diameter: 65 mm,
Height: 150mm) at 1500℃, and 1
After cooling to each temperature from 355°C to 1410°C at a cooling rate of 20°C/min, stirring was continued for 20 minutes with a stirring blade inserted into the crucible while maintaining the temperature, and the slag was removed from the crucible at each time. FIG. 2 is a graph showing the results of measuring the amount of crystals in a solidified sample after collecting it as a sample and rapidly cooling it with water. FIG.

Note that the amount of crystals was measured using X-rays.

In addition, Part 2 A shows the results of measuring the amount of crystals of the sample at each temperature when stirring for 20 minutes under the same conditions and when holding for 20 minutes without stirring.

As is clear from FIG. 2, the amount of crystals in the samples subjected to stirring treatment was significantly increased compared to those in untreated samples, clearly demonstrating the effect of stirring on promoting crystal growth.

Moreover, according to Figure 1, this growth and increase of crystals is achieved by stirring in an extremely short time, and in particular, it has been found that in the case of slag at temperatures below 1400°C, a saturation amount has already been reached in less than about 10 minutes of treatment. do.

Due to the high viscosity of the molten slag, this mechanism of crystal growth makes it difficult for so-called homogeneous nucleation, in which crystal nucleation occurs uniformly and spontaneously in a supercooled state, unlike in general melt, to occur.
This is mainly due to the fact that it is dominated by heterogeneous nucleation accompanied by nucleation between the interfaces between the melt and impurities and the vessel wall, and the stirring action of the slag causes the nuclei generated on the vessel wall to be sequentially transferred to the melt. In order to capture and disperse the new melt inside and bring the new melt into contact with the wall surface, the effective surface area of the inner wall of the container, which is the base for nucleation, and the contact area between the generated nuclei and the melt are greatly increased, and as a result, the overall nucleation It is believed that the speed increases and crystal growth is rapidly promoted.

As mentioned above, the present inventors have discovered and confirmed the fact that the stirring treatment of slag and its effects have a significant effect on the growth and promotion of crystals in the production of slag containing crystals. The present invention has been completed, and the gist of the present invention is to turn the slag into a slag based on the pre-stirring of the slag.

Now, to discuss the stirring conditions that are important in carrying out the present invention, the stirring means includes not only ordinary stirring in which a stirring blade is immersed in the slag and rotated, but also a stirring body. Any stirring method can be used, such as by moving the slag up and down, or by rotating or vibrating the container (pot) itself, and in addition to these mechanical stirring methods, stirring by blowing gas into the slag and stirring by bubbling. You may do so.

Next, the temperature of the slag to be stirred is 1350°C to 140°C.
0°C is particularly preferred.

In other words, as can be seen from Figure 1, when the temperature exceeds 1400°C, there is a tendency for the crystal growth and promotion effect by stirring to decrease significantly, and there is also the problem that foaming tends to occur during the subsequent slag formation, and further stirring This has disadvantages such as shortened blade life.

On the other hand, if the temperature is lower than the lower limit of 1350°C, the viscosity of the slag increases and workability deteriorates, and it is difficult to efficiently quench and pulverize the slag when turning it into a slag, resulting in a tendency for the quality of the slag to deteriorate. In addition, the manufacturing time is generally longer and the advantages over conventional methods are lost.

In addition, the preferred range of stirring retention time varies depending on the target amount of crystals in the slag, the chemical composition of the slag, the stirring method, etc., but in general, the upper limit can be estimated from the results in Figure 1. The stirring time is about 15 minutes, and stirring for a longer time than this cannot be expected to increase the effect, but rather only unnecessarily prolongs the production time.

In carrying out the present invention, at the same time as the stirring or before or after the stirring process, it is preferable to add a powdery substance having basicity, such as blast furnace slag, converter slag, lime, dolomite,
It would be even more beneficial to add an appropriate amount of brick scraps, foundry waste sand, etc. as a nucleating material to promote the formation and growth of crystals.

The slag that has been subjected to the stirring process is rapidly cooled and turned into slag by the same method as before.

In other words, when the stirring device and other incidental equipment are removed from the pot and the pot filled with slag is gradually tilted, a film-like falling stream is continuously flowed down into the slag gutter located directly below it. At the same time, high-pressure water (for example, water pressure:
Inject 2-3 kg/cm2, flow rate 4-6 t/t of slag,
The water slag is collided, rapidly cooled and pulverized, and then flows into a storage pit installed at the bottom of the tip of the slag gutter, where it is cooled and turned into granular water slag of 5 mm or less.

Afterwards, this is dehydrated and dried, and an appropriate crushing process is added depending on the use of the water slag to adjust the particle size or shape before shipping.

As described above, according to the present invention, compared to the conventional water slag production method, the production time can be significantly shortened (about 1/6), and it can be fully adopted in the furnace front method, and has excellent It has the effect of being able to produce water slag containing very high-quality crystals in terms of workability, and is therefore generated in large quantities from steelworks as a raw material for the construction and civil engineering fields, especially as aggregate for concrete. It should be said that this invention has high industrial and technical value in the sense that it further expands the way to effectively consume blast furnace slag.

[Brief explanation of the drawing]

Figures 1 and 2 show the results of an experiment investigating the effect of stirring molten blast furnace slag on increasing the amount of crystals in the product.
The figure is a graph illustrating the relationship between the stirring holding time and the amount of crystals at each temperature, and FIG. 2 is a graph illustrating the relationship between temperature and the amount of crystals when stirring is carried out for a certain period of time and when it is held without stirring for the same period of time.

Claims (1)

[Claims] 1. After stirring the melting furnace slag at 1,350 to 1,400°C to promote crystal growth, a film-like falling flow is formed, and high-pressure water is injected and collided with the falling flow to turn it into quenched water slag. A method for producing blast furnace water slag containing characteristic crystalline substances.