JP6070614B2 - Pneumatic slag production apparatus, production method of crushed slag - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an apparatus for producing a crushed slag produced by pulverizing steelmaking slag, a method for producing the crushed slag, and an crushed slag.

  Slag produced as a by-product in the steel industry includes slag from blast furnaces, pretreatment processes, converters, electric furnaces, and the like. Of these, slag by-produced from the blast furnace is called blast furnace slag, and slag by-produced from the pretreatment process, converter, and electric furnace is called steelmaking slag.

  Steelmaking slag contains a lot of lime that is added as an auxiliary material in the steelmaking process, and a part of the lime is not completely dissolved and remains as free lime (hereinafter, free CaO) in the steelmaking slag. Yes. If free CaO is present in the steelmaking slag, when the steelmaking slag comes into contact with water, the free CaO hydrates and expands or elutes alkali.

  Therefore, in general, when steelmaking slag is used, the volume is stabilized by performing aging and reacting free CaO with moisture in advance to change to slaked lime. Aging includes atmospheric aging performed by the atmosphere in a yard and steam aging using steam (see Non-Patent Document 1).

  However, atmospheric aging requires a long period of time until the free CaO in the steelmaking slag is stabilized. Steam aging uses a large amount of steam and increases processing costs.

  Therefore, as a method other than aging for reducing the risk of hydration expansion of free CaO and alkali elution, for example, Patent Document 1 discloses that slag water is sprayed by spraying a high-pressure air flow onto a molten slag and rapidly cooling it. Techniques for reducing the risk of Japanese expansion and alkali elution are described.

JP 2004-238234 A

Steel Slag Association "Environmental Materials Steel Slag" August 2010

  However, the crushed slag produced in a granular form by pulverization has a spherical shape and therefore has a small angle of repose and is difficult to handle and store.

  The present invention has been made in view of the above, and has reduced the risk of hydration expansion and alkali elution, and is easy to handle and store. The purpose is to provide crushed slag.

In order to solve the above-described problems and achieve the object, the apparatus for producing pulverized slag according to the present invention blows an air flow to a molten slag that melts at 1550 ° C. or higher and has a liquid phase of 70% or higher. Means for producing particles, and means for producing flat-shaped crushed slag having an average flatness ratio of 0.6 or more by colliding the crushed crushed slag in a semi-molten state with a wall surface. It is characterized by providing.

In addition, the method for producing the pulverized slag according to the present invention includes a step of spraying an air stream onto molten slag having a liquid phase of 70% or more by melting at 1550 ° C. or more, and granulating and semi-molten. Producing a flat-shaped crushed slag having an average flatness ratio of 0.6 or more by colliding the crushed slag in a scattered state with a wall surface.

Moreover, the crushed slag according to the present invention is a flat crushed slag having an average particle size of 0.5 to 5 mm , and an average flatness ratio is 0.6 or more.

  ADVANTAGE OF THE INVENTION According to this invention, the risk of hydration expansion | swelling and alkali elution is reduced, and the manufacturing apparatus of the pulverized slag, the manufacturing method of pulverized slag, and the pulverized slag which can be handled and stored easily can be provided.

FIG. 1 is a schematic diagram showing a schematic configuration of a milled slag production system according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

  Based on the experiment described below, the inventors of the present invention scatters airflow when blowing airflow onto a molten slag that melts at 1550 ° C. or higher and has a liquid phase of 70% or higher. By making the slag collide with the wall surface, it is possible to produce flat-shaped crushed slag, and by making the average flatness of this crushed slag 0.6 or more, the angle of repose becomes 30 degrees or more, and it is actually used. It was found that the handling property can be improved.

  First, with reference to FIG. 1, a schematic configuration of a milled slag production system that is a milled slag production apparatus of the present embodiment will be described.

In this Embodiment, the decarburization slag (converter decarburization slag) in a converter is made into object as steelmaking slag. As shown in FIG. 1, the pulverized slag manufacturing system 10 includes a melting furnace 1, a firewood 2, a pipe 4, an air nozzle 5, and a wall surface 6, and a molten slag melted in the melting furnace 1. A flat shaped crushed slag (flat shaped crushed slag) 8 is produced from (molten slag) 3. In the air-pulverized slag manufacturing system 10, the converter decarburization slag is melted in the melting furnace 1 so that the discharge temperature of the converter decarburization slag becomes 1550 ° C. or higher. A trough 2 is installed in front of the melting furnace 1, and the molten slag 3 melted therein is poured. The trough 2 receives the molten slag 3 discharged from the melting furnace 1 and has a structure in which the molten slag 3 falls vertically from the tip. What is the melting furnace 1 by blowing a high-speed air flow to the molten slag 3 falling from the tip of the tub 2 using an air nozzle 5 having a cross-sectional area of 3 mm × 40 mm attached to the tip of the pipe 4? Dissolved slag 3 was scattered in the opposite direction to form a granular form (winded slag). The high velocity air flow was at a speed of 250 or 350 m / sec and a ratio of 0.25 m ³ / kg-slag. Moreover, the flat-shaped flat-shaped crushed slag 8 was manufactured by colliding the crushed crushed slag (spattered crushed slag) 7 with the wall surface 6 installed at a position 2 to 4 m ahead of the ridge 2. .

  As a result of producing the flat shaped crushed slag 8 under a plurality of conditions, the average particle size of the crushed slag was in the range of 0.5 to 5 mm. In addition, since the angle of repose is about 30 degrees at an average flatness ratio of 0.6, an improvement in handling properties in actual use can be expected by setting the average flatness ratio to 0.6 or more.

  Here, the flatness is defined by the following formula (1).

As described above, flat-shaped crushed slag that oxidizes iron in the slag to Fe ₂ O ₃ by air crushing and immobilizes free CaO to reduce the risk of hydration expansion and alkali elution, and is easy to handle and store. Can be manufactured.

  In addition, although the melting temperature of slag was 1550 degreeC or more, it is preferable that it is 1600 degrees C or less from the ease of fall from a wall surface and collection | recovery. In addition, the material of the wall surface 6 on which the molten slag collides needs to be a material that can withstand the collision of a high-temperature substance of 1500 ° C. or higher. Moreover, it is preferable that the wall surface 6 is a metal plate from a viewpoint of the peelability of slag. The installation position of the wall surface 6 is preferably about 10 m from the tip of the heel 2.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these embodiments. Various modifications according to specifications and the like are within the scope of the present invention. It is obvious from the above description that various other embodiments are possible within the scope of the above.

[Example]
In this example, converter decarburization slag was used. Although converter decarburization slag varies slightly depending on the steel plate components being produced, Table 1 shows examples of the composition of the converter decarburization slag used (described in two examples). In Table 1, T.W. Fe indicates the total Fe concentration in the slag. In addition, M.M. Fe indicates the metal Fe concentration in the slag. Moreover, T-CaO shows the total CaO density | concentration in slag. Moreover, f-CaO shows the density | concentration of the free CaO in slag.

The discharge temperature (slag temperature) of the converter decarburization slag from the melting furnace 1 is changed, and the velocity of 80 or 120 m / sec is used for the molten slag 3 falling from the tip of the tub 2 using the air nozzle 5. The high-speed air flow was sprayed at a ratio of 0.40 m ³ / kg-slag, and the molten slag 3 was scattered in the direction opposite to the melting furnace 1. Moreover, the wall surface 6 was installed in the position of 8-12m ahead of the eaves 2, and the crushed slag 7 was made to collide during scattering, and the crushed slag was obtained.

  These results are shown in Table 2. As shown in Examples 1 to 5, when the temperature at the time of discharging the molten slag 3 from the furnace is 1560 ° C. or higher, the flatness of the crushed slag is high regardless of the flow rate of the high-speed air flow and the distance from the ridge 2 to the wall surface 6. It was 0.6 or more, and it was found that the temperature of the molten slag 3 has a great influence on the flatness of the crushed slag. Moreover, in the comparative example whose temperature at the time of discharge | emission of the molten slag 3 is 1520 degrees C or less, the flatness ratio of the crushed slag was 0.4 or less in all.

As an example of the composition of the manufactured crushed slag, FeO is 1.7% by mass, Fe ₂ O ₃ is 31.2% by mass, SiO ₂ is 10.9% by mass, CaO is 45.2% by mass, Al ₂ O ₃ was 1.1% by mass and MgO was 7.1% by mass. FeO has decreased from 6.95% by mass before wind-pulverization, Fe ₂ O ₃ has increased from 20.3% by mass before air-crushing, and iron in the slag is oxidized by air-crushing Was confirmed. The diameter of the blown slag was 95% or more when it was 5 mm or less.

In addition, as shown in Comparative Examples 1 to 5, when the discharge temperature (slag temperature) from the melting furnace 1 is set to 1520 ° C. or less, the discharge temperature was low, so that the solidified before the collision with the wall surface 6 and the average flatness Became 0.1 or less. The diameter of the blown slag was 95% or more when the diameter was 3 mm or less. The slag composition of an example of the comparative example is as follows: FeO is 2.7 mass%, Fe ₂ O ₃ is 33.3 mass%, SiO ₂ is 10.6 mass%, CaO is 44.2 mass%, and Al ₂ O ₃ is The content was 1.7% by mass and MgO was 5.6% by mass. FeO is decreased from 6.95% by mass before air-crushing, and Fe ₂ O ₃ is increased from 20.3% by mass before air-crushing. This confirmed that the iron in the slag was oxidized.

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 桶 3 Molten slag 4 Piping 5 Air nozzle 6 Wall surface 7 Spattered crushed slag 8 Flat-shaped crushed slag 10 Pneumatic slag production system

Claims (3)

Means for injecting an air stream into molten slag having a liquid phase of 70% or higher by melting at 1550 ° C. or higher,
Means for producing a flat-shaped crushed slag having an average flatness ratio of 0.6 or more by colliding with a wall surface the crushed slag that is in the form of particles and is in a semi-molten state ,
An apparatus for producing crushed slag, comprising: A step of spraying an air stream onto molten slag that is melted at 1550 ° C. or higher and has a liquid phase of 70% or more to form particles;
A step of producing a flat-shaped crushed slag having an average flatness ratio of 0.6 or more by colliding with a wall surface of the crushed slag in a semi-molten state, which is granulated, and
The manufacturing method of the crushed slag characterized by including. A flat crushed slag having an average particle diameter of 0.5 to 5 mm , wherein the average flatness is 0.6 or more.

Images