JP2009280445A - Method and apparatus for pressurization type steam-aging system of steel slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to conduct hydration reaction in a short time regardless of kinds of steel slag. <P>SOLUTION: A method for aging steel slag 2 with pressurized steam is disclosed. A piping 5, designed to feed steam to a pressurized vessel 4, in which a slag-storing container 3 is inserted, is introduced inside the slag-storing container 3. Through the piping 5, steam is fed to the steel slag 2 loaded in the slag-storing container 3 so as to directly conduct hydration reaction of the steel slag 2. Any kind of steel slag can be subjected to hydration reaction in a short time within 2 hours because steam fully infiltrates into slag in a short time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for aging steelmaking slag containing unfoamed lime discharged by a converter, an electric furnace or the like in a short time using steam, and an apparatus for carrying out this method.

  Steelmaking slag generated in the steelmaking process is hard and has an angular surface, so that it is well meshed during road rolling and has excellent properties as a roadbed material.

  However, in the steelmaking slag, a part of quick lime used as a dephosphorizing agent / desulfurizing agent remains uncombined lime (also referred to as free lime) without being completely bonded to other molecules.

  Therefore, when this steelmaking slag is used as it is as a roadbed material, it may cause a hydration reaction over time to expand / collapse, resulting in adverse effects such as ground uplift.

  For this reason, when steelmaking slag is used as a roadbed material or the like, conventionally, aging for stable use is performed in advance to complete the expansion / collapse phenomenon. Aging is an operation of artificially swelling steelmaking slag containing undecomposed lime in a short time using water vapor.

One company of the applicant has proposed the technique of Patent Document 1 as an aging method and apparatus for steelmaking slag for the above purpose.
JP-A-8-165151

  In the technique proposed in Patent Document 1, first, steel slag having a normal particle size of 25 mm or less and crushed so that the particle size is 80% or more is charged into a pressure vessel, and the pressure vessel is sealed and placed in the vessel. Pressurized steam is supplied to heat the container and slag. Then, the temperature inside the pressure vessel is increased while the hot water condensed by this operation is discharged, and then the inside of the vessel is kept in a saturated steam atmosphere at a pressure of 0.196 to 0.98 MPa for 1 to 5 hours. The inside of the container is depressurized to atmospheric pressure and steelmaking slag is discharged.

Further, in Japanese Patent Application Laid-Open No. 2004-228867, one of the applicants releases air-mixed vapor accumulated inside the pressure vessel to the outside of the pressure vessel in accordance with the temperature raising / pressure-raising step in the pressure vessel and the temperature maintaining step in the saturated water vapor atmosphere. A steelmaking slag aging method and equipment characterized by this were proposed.
JP-A-9-118549

An outline of steam aging using the apparatus proposed in Patent Document 2 is shown in FIG.
That is, the steelmaking slag 2 to be steam-aged is charged into the non-sealed slag storage container 3 by the carry-in device 1.

  The slag storage container 3 is transferred into the pressure vessel 4 and the inside of the pressure vessel 4 is held at a predetermined pressure for a predetermined time by saturated steam supplied from a steam supply port 4a provided above the steel slag. Aging. The slag after the aging process is carried out by opening the bottom of the slag storage container 3.

  However, when, for example, hot metal pretreatment slag, electric furnace reduction slag, and the like are subjected to pressure aging using the above-mentioned apparatus, it takes a long time for the steam to sufficiently reach the slag, and in a short time (within 2 hours). It has been found that the hydration reaction may be difficult.

  The problem to be solved by the present invention is that the conventional steam aging takes a long time for the steam to sufficiently spread in the slag depending on the type of steelmaking slag, and the hydration reaction within 2 hours is difficult. It is a point that it may become a situation.

The pressurized steam aging method for steelmaking slag of the present invention is as follows.
To enable hydration reaction in a short time regardless of the type of steelmaking slag,
In the method of aging steelmaking slag with pressurized steam,
A pipe provided to supply steam to the pressure vessel into which the slag storage container is inserted is led into the slag storage container,
The most important feature is that the steelmaking slag is directly hydrated by supplying steam to the steelmaking slag charged in the slag storage container through this pipe.

Pressurized steam aging method of steelmaking slag of the present invention,
A pressure vessel;
Piping for supplying steam into the pressure vessel;
A slag storage container inserted into the pressure container;
The said piping can be implemented using the pressurization type steam aging apparatus of the steelmaking slag of this invention led to the inside of the said slag storage container.

  In the present invention, the steam supply pipe is guided to the inside of the slag storage container, and the steam is supplied to the steelmaking slag in the slag storage container through this pipe. The slag is sufficiently spread and hydration can be performed within a short time of 2 hours.

The inventors examined the cause of the above problem.
Conventional converter slag, which has been mainly handled in the past, is cooled from a molten state and has a rock shape. Therefore, when pressurized steam aging is performed, the converter slag is reduced to 25 mm or less by an appropriate crushing means. It is crushed so that the particle size is 80% by mass or more.

  In this crushing, excessive crushing leads to an increase in cost. Therefore, crushing is generally performed so that the crushed particle size tends to be large within a specified particle size. An example of the particle size distribution after crushing the converter slag is shown in Table 1 below.

  When converter slag having the particle size distribution shown in Table 1 and having a water immersion expansion ratio of 5 to 8% is subjected to pressurized steam aging, as shown in FIG. The process is being carried out to make it less than 5%. This 3-hour cycle is a cycle in which the temperature is raised for 40 minutes, held for 2 hours, then cooled for 10 minutes and then discharged in 3 minutes.

  By the way, also in the hot metal pretreatment slag, the electric furnace reducing slag, and the converter slag, defluorination is currently promoted due to environmental improvement (elution, reduction of content fluorine). An example of the particle size distribution of the electric furnace reducing slag, which is a kind of steelmaking slag, is shown in Table 2 below, and has a large amount of powdery material having a particle size of 0.425 mm or less.

  When steelmaking slag having a large blending ratio of such powder is subjected to pressurized steam aging, it takes about 4 hours for steam to reach the inside of the slag. This is presumably because the current pressurized aging apparatus has the steam supply port 4a installed at the upper part of the pressure vessel 4 and the pressurized steam is supplied only from the upper part of the pressure vessel 4 as shown in FIG. .

  Therefore, after the temperature rise, if it is held for 2 hours as in the conventional case, the process becomes a cycle of about 6 hours, and the aging process by the hydration reaction in the short time (2 hours), which is the feature of this equipment, is difficult. become.

  The temperature measurement position in the slag when the steelmaking slag 2 charged in the slag storage container 3 of the conventional aging apparatus shown in FIG. 6 is aged is shown in FIG. 2, and the results of the temperature measurement are shown in FIG. Show.

  Therefore, the inventors have studied the improvement of the path for supplying steam to the slag storage container for storing the steelmaking slag, and as a result, have established the following present invention.

  As shown in FIG. 4, the present invention guides the pipe 5 for supplying steam to the pressure vessel 4 into which the slag storage container 3 is inserted into the slag storage container 3, and during the aging treatment of the steelmaking slag 2, for example, The pipe 5 is covered with the steelmaking slag 2 in the slag storage container 3.

  In the present invention, for example, by injecting steam from the hole 5a provided in the pipe 5, for example, compared to the conventional method in which steam is supplied from the upper part of the steelmaking slag 2 charged in the slag storage container 3, The time required to spread steam throughout the steelmaking slag 2 is greatly reduced.

  FIG. 5 shows the measurement results of the temperature in the slag when the above-described present invention is applied and the converter slag is subjected to pressurized steam aging.

  As is clear from FIG. 5, when the present invention is applied, the difference due to the measurement position shown in FIG. 2 is negligible, and the steelmaking slag in the slag container is uniform to the extent that there is no operational problem. It can be seen that the temperature has risen.

  In other words, in the present invention, the pipe for supplying steam is arranged inside the slag storage container, so that the temperature rise time is 40 minutes and the cycle time is reduced.

  Incidentally, from the two pipes arranged in the position shown in FIG. 4 inside the slag storage container, 85 kg of steam of 0.49 MPa pressure is injected per ton of slag, and the 46 ton of slag storage container is charged. Steelmaking slag was aged.

  Table 3 below shows a comparison with the case where the steam is supplied only from the steam supply port installed in the upper part of the pressure vessel as shown in FIG.

  Although there was no difference in the heat retention time and the cooling time in the present invention and the conventional one, since the slag particle size is small, the difference required in the temperature rising time is large in the present invention and the conventional one, and the conventional one required 4 hours. By applying the present invention, it could be 2 hours.

  It goes without saying that the present invention is not limited to the above-described examples, and the embodiments may be changed as appropriate within the scope of the technical idea described in each claim.

  For example, in the above example, the pipe 5 is provided with a number of holes 5a to inject steam into the steelmaking slag 2, but the pipe may be provided with slits.

  The present invention as described above is not limited to steelmaking slag having a high blending ratio of powdery substances, but can also be applied to steelmaking slag having a particle size comparable to that of a conventional roadbed material. Incidentally, it took about 40 minutes in the past to increase the temperature of the steelmaking slag having a particle size of about the roadbed material, but when the present invention was applied, the increase in temperature could be completed in 10 to 20 minutes.

It is the figure which showed the basic cycle of steam aging. It is the figure which showed the temperature measurement position in the steelmaking slag accommodated in the slag storage container, (a) is the figure seen from the side surface, (b) is the figure seen from the plane. It is the figure which showed the measurement result of the temperature in slag at the time of aging using the conventional aging apparatus. It is a figure explaining schematic structure of the aging apparatus of this invention, (a) is the figure seen from the side surface direction, (b) is the figure seen from the plane direction. It is the figure which showed the measurement result of the temperature in slag at the time of aging using the aging apparatus of this invention. (A) is a figure which shows the outline | summary of the steam aging using the conventional installation, (b) is an enlarged view of a slag storage container part.

Explanation of symbols

2 Steelmaking slag 3 Slag storage container 4 Pressure vessel 5 Piping 5a Hole

Claims (3)

In the method of aging steelmaking slag with pressurized steam,
A pipe provided to supply steam to the pressure vessel into which the slag storage container is inserted is led into the slag storage container,
A pressurized steam aging method for steelmaking slag, wherein the steelmaking slag is directly hydrated by supplying steam to the steelmaking slag charged in the slag storage container via the pipe. A pressure vessel;
Piping for supplying steam into the pressure vessel;
A slag storage container inserted into the pressure container;
A pressurized steam aging apparatus for steelmaking slag, wherein the pipe is led into the slag storage container.   3. The pressurized steam aging device for steelmaking slag according to claim 2, wherein the pipe is provided with a plurality of holes for steam injection.

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