JP3267737B2 - How to treat steelmaking slag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is intended to accelerate the hydration reaction of solidified high-temperature steelmaking slag by contacting it with a large amount of cooling water, and to further shorten the aging time of the crushed steelmaking slag. And a method of treating steelmaking slag.

[0002]

2. Description of the Related Art In conventional steelmaking slag processing, slag carried out of a steelmaking factory is discharged onto a pit or an iron plate and subjected to various processing steps such as temporary crushing, temporary cooling, secondary cooling, and submerged pit cooling. You. The slag subjected to these treatments is left in a cooling yard for about 1 to 2 days and is naturally cooled.
After that, secondary crushing, magnetic separation and grinding are performed, and iron and the like are recycled to the steel making process. The slag from which iron has been recovered is transported to an aging yard, and left for about 1 to 3 years to be used for civil engineering and building materials, and then subjected to an aging treatment. This conventional processing method is uneconomical, requiring multiple steps, long processing times and large yards. Furthermore, since these series of processes are operations involving high temperature and dust, there is a problem in terms of safety and health.

[0003] In order to solve these problems, various techniques have been disclosed with respect to a slag aging treatment method. As one of the methods, a processing method for stabilizing, cooling and reforming slag described in Japanese Patent Publication No. 58-55093 discloses a method of solidifying a molten slag and then crushing the obtained slag to obtain a small piece of slag in a closed container. The slag is sprinkled with water, and the slag is aged and cooled by utilizing the pressure of the generated steam and a high-temperature atmosphere.
However, since this technique has a problem in a watering method, hydration does not sufficiently progress even if the treatment is performed for a long time, and aging is insufficient. In addition, since the crushing is not performed at all in this process, a post-process of the crushing process and the aging process is necessary in order to be usable for civil engineering and the like.

Japanese Patent Application Laid-Open No. 61-101441 discloses a method for improving steelmaking slag into slag suitable for road materials, harbor construction and the like in a short period of time. In this method, after steelmaking slag is piled up in a yard, 80 to 100
After heating for 48 hours or more with steam at ℃, and curing in air for 7 days, the hydration reaction of free lime etc. in the slag is promoted, and aging is finished in a short time.
Even with this technique, in order to satisfy the residual expansion rate of 2% or less, which is the standard for use in civil engineering and building materials, it is necessary to perform aging for 7 days in the atmosphere after heating steam for 48 hours or more. Further, in this processing method, since slag is not crushed, a crushing process is required in advance. Furthermore, no hydration reaction takes place inside the large slag, which requires sorting of this large slag after this treatment.

[0005] The applicant of the present invention has disclosed in Japanese Patent Application No. 4-97699 that the sprinkling speed, steam pressure and processing time in a closed vessel filled with coarsely crushed high-temperature slag are limited, and the self-crushing is carried out by rapid cooling and hydration. Treatment (Slag Quench) which causes hydration on the new fracture surface
Process). 3 by this processing method
By processing for 0 minutes, the average slag particle size is 11 to 18 m.
m, a slag having a residual expansion rate of 3 to 12% (average 8%) is obtained.

[0006]

SUMMARY OF THE INVENTION The present invention provides a steelmaking slag which has been roughly crushed and which has been subjected to the above-mentioned SQ treatment of the present applicant to crush the slag and promote the hydration reaction.
The heat of the high-temperature steelmaking slag generated by the SQ treatment and the heat of the hydration reaction are effectively used for the aging treatment with steam in the subsequent process, and the 2% residual expansion rate required for civil engineering building materials can be reduced in a very short time. The purpose of the present invention is to achieve aging of steelmaking slag economically and safely.

[0007]

SUMMARY OF THE INVENTION The above object is achieved according to the present invention, steelmaking performing crushing processing Ri及 beauty aging process slag
In the method for treating slag, high-temperature slag mechanically coarsely crushed is filled in a core container in a pressure vessel, and after sealing the pressure vessel, cooling water is supplied from above the slag packed bed with 5 to 30 ton / Water is sprayed at a water spray density of hrm ² , and the steam generated by the contact between the cooling water and the high-temperature slag increases the steam pressure in the pressure vessel. The relationship between the steam pressure and the processing time is expressed by the following equation (1): 3.50 ≧ P ^0.6 × T ^0.4 ≧ 1.48 (1) where P: steam pressure (kg / cm ² ) T: treatment time (hr) Aging and crushing by rapid cooling with cooling water and slag expansion by hydration reaction, and then heating the aged and crushed slag with steam at 80 to 100 ° C. for 12 hours. It is achieved by processing method steelmaking slag, characterized in that exposure or between and be aged by water vapor.

Furthermore, the object is achieved according to the present invention, the steel slag performing crushing processing Ri及 beauty aging process slag
In the treatment method, the steelmaking slag treatment method is characterized in that aging with steam is performed using the steam generated by contact between cooling water and high-temperature slag.

[0009]

According to the two-step method for treating steelmaking slag of the present invention, in which the SQ treatment and the steam treatment in the subsequent step are carried out, the hydration reaction is effectively and rapidly promoted by the first-stage SQ treatment. Due to the expansion of the hydration reaction, the slag is self-crushed, and the aging of the slag greatly progresses. Further, by performing the aging treatment with the second stage steam using the sensible heat of the slag collected in the SQ treatment, the aging of the slag further progresses, and the product can be satisfied as a civil engineering building material. The above-mentioned SQ processing and steam processing methods have tremendous effects on economy and safety such as a drastic reduction in processing time, simplification of processing steps, reduction in processing costs and equipment investment compared to the prior art. . The operation will be described below.

Free CaO present in steelmaking slag reacts with water or steam to cause a hydration (digestion) reaction represented by the following formula. CaO + H ₂ O = Ca (OH) ₂ +15.2 Kcal Calcium hydroxide (Ca (O)
Since H) ₂ ) expands in volume, the slag is self-crushed by calcium hydroxide generated in the slag. This hydration reaction proceeds at a relatively low temperature and is an exothermic reaction, and thus requires an appropriate cooling.

In the SQ treatment in which self-crushing and aging progress by rapid cooling and hydration reaction of the first-stage slag, a mechanically coarsely crushed high-temperature slag is filled in a core container in a pressure vessel. After closing the container, cooling water is sprinkled from above the slag packed bed at a sprinkling density of 5 to 30 ton / hrm ² . This sprinkling may be performed intermittently at intervals according to the conditions of the cooling and hydration reactions. 5 ton / hrm
^With a watering density of ² or more, cooling water is evenly applied to the slag packed layer and all slag in the container undergoes hydration reaction and rapid cooling without causing drift, and at the same time heat shrinkage due to rapid cooling and hydration reaction The hydration reaction proceeds further on the newly emerged fracture surface that has been fractured by expansion. Even if water is sprayed at a watering density exceeding 30 ton / hrm ² , the cooling rate of the slag does not change, and the steam in the pressure vessel is excessively cooled, so that external steam supply is required to maintain the pressure.

In the SQ treatment, the steam pressure in the pressure vessel is increased by the steam generated by the contact between the cooling water and the high-temperature slag and the steam injected from the outside, and the relationship between the steam pressure and the processing time is expressed by the following equation (1). ): 3.50 ≧ P ^0.6 × T ^0.4 ≧ 1.48 (1) However, P is maintained within the range specified by the following: steam pressure (kg / cm ² ) T: treatment time (hr) By specifying the steam pressure (P) and the treatment time (T), self-crushing occurs, and the self-crushing causes a hydration reaction on the newly appeared crushed surface,
Therefore, not only the hydration reaction area is increased, but also the slag temperature is lowered, so that the hydration reaction accompanied by heat generation is further promoted. By the short-time SQ treatment for about 30 minutes, the residual expansion rate due to unreacted slag is 3 to 12% (average 8).
%). In order to reduce the residual expansion rate of the slag to a residual expansion rate suitable for sale (2% or less), the conventional open stacking method required an aging period of 12 to 36 months of atmospheric exposure. However, the slag in the state where the SQ processing is performed is shortened to the aging period of the atmospheric exposure of 6 to 9 months.

Further, in order to reduce the residual expansion rate to 2% or less in a short period of time, in the present invention, in order to more effectively and economically treat the slag subjected to the SQ treatment, the slag is heated to 80 to 80% by heating with steam. An aging treatment with water vapor at the second stage exposed at 12 hours or more at 100 ° C. is performed. This steam aging treatment is preferably performed at a temperature of 90 ° C. or higher, and steam having an average temperature of 95 ° C. This aging treatment with water vapor may be performed in the above-mentioned pressurized container. In this case, the opening / closing part or the exhaust valve at the upper part of the pressure container is opened to make the pressure approximately equal to the atmospheric pressure. Moreover, you may perform in another arbitrary container or earthen place provided separately. This aging treatment with water vapor uses water vapor generated at the time of SQ processing,
Alternatively, steam supplied from outside may be used. SQ
When water vapor generated at the time of processing is used, the water vapor cost can be reduced to zero, which has a great effect in reducing the aging processing cost.

According to the two-stage treatment method of the present invention in which steam treatment is further performed after SQ treatment, crushing and aging of steelmaking slag can be performed in a very short time.
Aging treatment for 2 to 36 months is not required. Further, since the aging treatment time is very short as compared with the conventional aging method using only water vapor, the aging equipment used for the treatment may be small in scale, and the capital investment amount can be greatly reduced. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0015]

EXAMPLES The results of the two-stage treatment method of the present invention in which steam aging treatment is further performed after the SQ treatment, and the results of converter slag, de-PS slag, and ingot slag treated by the prior art treatment method are shown below. FIG. 1 shows the steam treatment time, residual expansion rate, and the like of the converter slag (a), the PS-removed slag (b), and the ingot slag (c) treated by the two-stage treatment method of the present invention and the conventional treatment method. Shows the relationship. When the treatment is performed by the two-stage treatment method of the present invention, the 2% residual expansion rate at which the converter slag (a), the PS removal slag (b), and the ingot slag (c) can be sold is 12 hours or less. Achieved well in processing time. The two-stage treatment method of performing the steam treatment after the SQ treatment of the present invention has an aging effect superior to the prior art treatment method using only steam.

[0016]

The aging of steelmaking slag by the two-stage treatment method of the present invention can achieve a residual expansion rate of 2% or less in any of converter slag, de-PS slag, and ingot slag within 12 hours. Aging effect suitable for sale is obtained. Accordingly, the converter slag, the PS removal slag, and the ingot slag need not be aged in the yard, and can be immediately sold.

[Brief description of the drawings]

FIG. 1 shows steam treatment time and residual expansion rate of converter slag (a), PS slag (b), and ingot slag (c) treated by the two-stage treatment method of the present invention and the treatment method of the prior art. The relationship is shown below.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Shinji Matsuo 1 Nishinosu, Oita, Oita City, Oita Prefecture Inside Nippon Steel Corporation (72) Inventor Tsukasa Kashiwara 1 Nishinosu, Oita Oita City, Oita New Japan (58) Field surveyed (Int. Cl. ⁷ , DB name) F27D 15/00-15/02 C04B 5/00-5/02 C21B 3/06

Claims (2)

(57) [Claims] The method according to claim 1] crushing processing Ri及 beauty aging process of the slag
In the method for treating steelmaking slag to be performed, a high-temperature slag that has been mechanically roughly crushed is filled in a core container in a pressure vessel, and the pressure vessel is sealed. Water is sprinkled at a sprinkling density of 30 ton / hrm ² , and the steam pressure in the pressure vessel is increased by the steam generated by the contact between the cooling water and the high-temperature slag, and the relationship between the steam pressure and the processing time is expressed by the following equation (1): .50 ≧ P ^0.6 × T ^0.4 ≧ 1.48 (1) where P: steam pressure (kg / cm ² ) T: treatment time (hr) Aging of the high-temperature slag that has been performed, and crushing is performed by rapid cooling with cooling water and slag expansion by a hydration reaction. Processing method of steelmaking slag condition in exposed more than 12 hours and carrying out aging with water vapor. The method according to claim 2] crushing processing Ri及 beauty aging process of the slag
The method for treating steelmaking slag according to claim 1, wherein in the method for treating steelmaking slag to be performed, aging with steam is performed using the steam generated by contact between cooling water and high-temperature slag.