JPH05112805A - Production of light slag - Google Patents

Abstract

PURPOSE:To efficiently produce a slag product having small unit weight in high yield. CONSTITUTION:For example, after steam is injected into molten slag 2 flowed out from a blast furnace through a slag tapping trough 1, cooling water 6 is spread and the slag is rapidly cooled. In order to inject the steam, a steam injecting nozzle 3 as possible to ascend/descend is immersed into the molten slag 2 flowing down the slag tapping trough 1. By injecting the steam, the molten slag 2 is stirred and the steam is efficiently dissolved into over the whole molten slag 2. The dissolved steam is reacted with nitrogen, carbon, etc., in the molten slag 2 to foam the slag. As a result, the light slag is produced in the high yield.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing light blast furnace slag.

[0002]

2. Description of the Related Art Blast furnace slag is consumed in various fields as a by-product of steelmaking. Considering the use of blast furnace slag as aggregate, fertilizer, etc., blast furnace slag is treated by either slow cooling or rapid cooling (water granulation). For example,
The slowly cooled slag is used as a road material, a coarse aggregate for concrete, and the like. On the other hand, granulated slag is used as a cement material, siliceous fertilizer and the like.

As a recent trend, the demand for water granulated slag is increasing. In addition, for the purpose of increasing the added value of blast furnace slag, its application to culture soil for gardening and outer wall materials has been studied recently. When the blast furnace slag is used for such an application, it is required that the slag powder has a small unit volume weight (hereinafter, referred to as unit weight). However, in the case of the usual water granulation method, it is impossible to constantly produce slag powder having a small unit weight, as in the case of floating granulation.

[0004]

That is, in order to manufacture a slag having a small unit weight, the reaction between water and slag is sufficiently performed in a short time before the slag is solidified, and the generated bubbles are released. It is necessary to solidify the slag before. However, in the usual water granulation method, the cooling rate of the slag is higher than that in the steam dissolution reaction. Therefore, although the amount of bubbles generated is small and an extremely light product can be partially produced, the average unit weight is about 1.0 to 1.3.

Factors affecting the unit weight of the granulated slag include the molten slag temperature, the slag basicity, the slag / water ratio,
It is known in the field operation that there are water temperatures and the like. For example, Japanese Examined Patent Publication No. 27070/1990 proposes to promote the foaming of slag by controlling these factors to achieve a lighter weight. In this method, blowing water having a temperature of 75 ° C. or higher is heated to a temperature of 14 at a water / slag ratio of 2 to 4.
It is sprayed on slag of 80 ℃ or higher. Under these conditions, the slag is gently cooled as compared with the usual water granulation method.
However, in order to carry out a sufficient foaming reaction, the cooling rate is still too high and the total amount of slag cannot be lightened.

The present invention has been devised to solve such a problem, and an object thereof is to blow foams prior to quenching to promote foaming and reduce the weight of slag.

[0007]

In order to achieve the object, the manufacturing method of the present invention is characterized in that a rapid cooling treatment is carried out immediately after the steam is blown into the molten slag discharged from the blast furnace. Specifically, the steam is blown into the molten slag flowing through the slag and the slag is foamed by allowing the slag and the steam to sufficiently react under the slow cooling condition. Then, the light slag is manufactured by quenching the slag. As a quenching method, a method of quenching with water using an ordinary granulated slag manufacturing apparatus, a method of granulating and quenching with a gas such as air, etc. are adopted.

[0008]

[Function] Foaming of blast furnace slag during water granulation is presumed to occur due to the following reaction. (O ₂ ⁻ ) + H ₂ O (g) = 2 (OH ⁻ ) [Dissolution of water vapor] ... (1) 2 (N ^{3 −} ) +6 (OH ⁻ ) = N ₂ (g) + 3H ₂ (g ) +6 (O ^{2 −} ) ・ ・ ・ ・ (2) 2 (CN ⁻ ) +6 (OH ⁻ ) = N ₂ (g) + 3H ₂ (g) + 2CO (g) +4 (O ^{2 −} ) ・ ・ ・ ・ ( 3) (C ₂ ^2- ) +6 (OH ⁻ ) = 2CO (g) + 3H ₂ (g) +4 (O ^{2 −} ) ... (4)

Therefore, when the steam is blown into the molten slag, the inside of the slag is sufficiently stirred and the steam is efficiently dissolved in the molten slag according to the reaction formula (1). At this time, since the cooling ability of water vapor is extremely smaller than that of water, the molten slag is kept at a high temperature without solidifying. Moreover, the effect of accelerating mass transfer by stirring the slag bath with water vapor is added, and the reactions of the reaction formulas (1) to (4) are efficiently promoted. By rapidly cooling the slag foamed in this way, a light slag can be manufactured.

The present invention has been completed based on the effect of the steam injection on the molten slag, and is carried out by using the apparatus shown in FIG. 1, for example. That is,
To the molten slag 2 flowing out of the blast furnace via the slag gutter 1,
Immerse the steam injection nozzle 3. The steam injection nozzle 3 is vertically movable by a nozzle elevating device 4, and the immersion depth in the molten slag 2 is adjusted. The steam injected from the steam injection nozzle 3 into the molten slag 2 reacts with the molten slag 2 to accelerate the foaming reaction.
Next, the molten slag 2 is rapidly cooled by the cooling water 6 jetted from the fountain nozzle 5.

The amount of cooling water 6 was maintained at a constant amount of 40 m ³ / min, and the distance between the steam injection position and the slag quenching point was 1.2 m, and the amount of steam injected into the molten slag 2 was changed. The unit weight of the obtained product slag was measured and shown in FIG. 2 in relation to the amount of steam injected. As is clear from FIG. 2, the unit weight of slag decreases as the amount of steam injected increases.

The amount of cooling water 6 was kept constant at 40 m ³ / min and the amount of steam injected was kept constant at 20 kg / min, and the distance between the steam injection position and the slag quenching point was changed.
Then, the unit weight of the obtained product slag was measured and shown in FIG. 3 in relation to this distance. In this test range, the unit weight tends to increase slightly as the distance between the steam injection position and the slag quenching point increases. However, the effect of distance on the unit weight is small.

[0013]

EXAMPLE A continuous operation was carried out for 30 minutes using the apparatus shown in FIG. As the water vapor injection nozzle 3, one made of copper and having a triple tube structure in which air for cooling the nozzle is made to flow through the outer tube was used. On the other hand, for the injection of the cooling water 6, the existing water granulation equipment was used. And, the water pressure of the cooling water is 2 kg / c.
m ² and the maximum spray rate were set to 50 m ³ / min. Table 1
Indicates the operating conditions at this time.

[0014]

[Table 1]

The resulting product slag has an average unit weight of 0.3.
It was 8. When this product slag is suspended in water, 9
0% or more floated. This indicates that the promotion of the foaming reaction by the steam injection was carried out almost uniformly over the entire molten slag in combination with the stirring effect of the steam.

[0016]

As described above, in the present invention, by blowing steam into the molten slag, the foaming reaction is promoted while stirring the molten slag. As a result, a product slag with a small unit weight can be constantly obtained, and the blast furnace slag can be used for applications with high added value. Moreover, since the unit weight is constant, the reliability of the product is high.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used in an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the amount of steam injected and the unit weight of product slag.

FIG. 3 is a graph showing the effect of the distance between the steam injection position and the slag quenching point on the unit weight of the product slag.

[Explanation of symbols]

1 Debris gutter 2 Molten slag 3 Steam injection nozzle 4 Nozzle lifting device 5 Fountain nozzle 6 Cooling water

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshio Yanagawa 11-1 Showa-cho, Kure-shi, Hiroshima Nisshin Steel Co., Ltd. Steel Research Laboratories (72) Inventor Hiroshi Okusu 11-11 Showa-cho, Kure-shi, Hiroshima Japan Shin Steel Co., Ltd. Steel Research Institute

Claims (1)

[Claims] 1. A method for producing a light slag, which comprises performing a quenching process immediately after injecting steam into a molten slag discharged from a blast furnace.