JPH08325619A - Method for restraining foaming of steelmaking slag - Google Patents

Abstract

PURPOSE: To provide a method for efficiently, safely and inexpensively restraining the foaming of steelmaking slag in a slag pan. CONSTITUTION: At the time of restraining the foaming of the steelmaking slag in the slag pan 3, atomized water is spread on the slag surface in the slag pan 3 to restrain the foaming of the steelmaking slag. Further, the supplying speed of the spread water is made to be 15-70l/min/m<2> of the slag surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing forming of steel slag by spraying water in the form of powder mist on the surface of slag in a slag pan.

[0002]

2. Description of the Related Art As a technique for suppressing the formation of slag, a method of introducing a lump substance having carbon as a main component or a lump substance having a mixture of carbon and converter slag is generally used. For example, in Japanese Examined Patent Publication No. 57-39291, pulp-sludge and industrial wastes containing 30% or less of impurities such as Al ₂ O ₃ and SiO ₂ are used as a main component, and 30 to 50% of small particle substances obtained by crushing slag are mixed. A slag soothing agent for a converter is described in which a kneaded product is molded by adding a small amount of an olefin polymer, and solidified into a granular or lump having a particle size of 20 to 80 mm. Further, the publication describes that when the sedative is put on the converter slag, it has a rapid sedative effect.

Further, in Japanese Patent Laid-Open No. 57-161017, a molded body containing 30 to 70% of a refractory substance, 20% or less of pulp sludge, 20% or less of an organic substance and 30% or less of a binder is put into a converter. A method for suppressing foaming of slag is described. In Japanese Patent Publication No. 63-61368,
For the purpose of suppressing the foaming of the slag on the hot metal, there is a description of a slag foaming preventing material containing an oxidizer composed of a light metal powder, a carbonaceous powder and sodium nitrate.

These methods are intended for the converter and the hot metal pretreatment process, and there is no good method for forming that occurs in the slag pan. The present situation is that workers take measures such as throwing in an appropriate size of raw wood or retaining slag bread for calming.

Here, although the above-mentioned forming suppressing material is effective, the cost is high. The method using raw wood has a long forming sedation time and is expensive. In addition, the method of calming the slag bread by retaining it has technical problems to be solved, such as an increase in equipment cost due to an increase in the number of slag pans.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and proposes a method of suppressing the forming of slag in a slag pan safely, early, and inexpensively. .

[0007]

DISCLOSURE OF THE INVENTION The present invention is a method for suppressing forming of steel slag, which comprises spraying water in the form of powder mist on the slag surface in a slag pan. Further, it is a slag foaming suppressing method in which the supply rate of water to be sprayed is 15 liters / minute to 70 liters / minute per 1 m ^{2 of} the slag surface.

[0008]

The slag foaming phenomenon is a phenomenon in which air bubbles are trapped while passing through the slag layer and are difficult to separate from the slag, and push up the entire slag layer. In an extreme case, it induces the phenomenon that slag and molten iron scatter as bubbles break. Factors that influence the slag forming phenomenon are:
It is said that the amount and size of bubbles and the physical properties (viscosity and surface tension) of the slag. With respect to the amount of bubbles (forming gas amount), the forming increases, and the forming calms down above a certain amount of gas. .

Particularly, when the slag mixed with the molten iron is discharged into the slag pan, the carbon in the molten iron and the oxygen source (F
CO gas is generated by the reaction of eO) and the forming becomes more remarkable. On the other hand, there is no dogma about
It is said that it is easy to form such as high viscosity and low surface tension slag.

From the above, the inventors of the present invention invented a method of adding water to slag to shorten the time in the high viscosity and low surface tension region where slag foaming is likely to occur and to solidify the surface early. did.

First, the present inventors conducted a water addition test to the slag in the slag pan for the purpose of confirming the slag foaming soothing effect and safety by sprinkling water. As a result, it was confirmed that when the water was added in a concentrated manner, the slag foaming sedative effect was small, and the added water was covered with the reacted slag and caused a steam explosion to cause a bumping phenomenon. It was also found that when water is sprayed through a nozzle tip or the like, a minute forming phenomenon is temporarily activated on the surface of the slag, but is calmed down in a short time.

That is, in this method, by spraying water on the surface of the slag, the surface viscosity of the slag temporarily becomes a high-viscosity region where the slag is easily formed, so that a minute forming phenomenon is activated. It was learned that the slag degassing effect and the subsequent solidification of the slag surface subside the slag foaming.

Next, the inventors of the present invention investigated the sedation time and safety by changing various watering rates by the device shown in FIG. 1 for the purpose of optimizing the watering amount. 1A is a plan view and FIG. 1B is a front view. In the figure, 1 is watering,
2 is a nozzle tip, 3 is a slag pan, and 4 is a water injection pipe.

As a result, it was confirmed that when the water spray rate was less than 15 liters / minute per 1 m ^{2 of} slag surface, the slag calming time became long, and when it exceeded 70 liters / minute, the risk of steam explosion and the like increased. FIG. 2 shows the relationship between the watering speed and the slag sedation time. To maximize sedation time,
40 liter / min to 70 liter / min is preferable per 1 m ^{2 of} slag surface.

[0015]

【Example】

(Example 1) The slag in the converter is put in the slag pan in about 7-1.
5 tons of waste were removed. The slag was forming violently in the slag pan. The composition of molten iron at the time of blowing off the converter is C: 3.3
~ 3.8%, Si: 0.01 to 0.03%, Mn: 0.10 to 0.15%,
P: 0.010 to 0.025%, S: 0.005 to 0.025%, and temperature: 1350 to 1400 ° C. The component of slag is T. Fe:
8-20%, MnO: 6-8%, CaO: 30-40%, Si
_{O 2: 22~27%, P 2} O 5: 3~5%, MgO: 3~4
%.

In the example of the present invention, 1 m ² of slag surface was added to the slag.
Water was sprinkled at 50 liters / minute for about 2 minutes. The slag surface area at this time was 6 m ² , and a total of 600 liters of water was sprayed. Slag foaming subsided during watering. There is almost no forming suppression cost.

In Comparative Example 1, the slag foaming suppressing material containing the refractory material and the pulp sludge as the main components described in the prior art was added to the slag to suppress the forming. The sedation time required about 15 minutes, and a total of 2 t of the foaming suppressing material was required. In Comparative Example 2, forming was suppressed by making the slag pan stand by. It took about 40 minutes to subside. In this example, it is necessary to increase the number of slag pans by two.

(Example 2) About 7 to 15 t of slag in the converter was discharged into a slag pan. The slag sometimes formed in the slag pan. The components of molten iron at the time of blowing off the converter are C: 0.03 to 0.90%, Si: tr, Mn: 0.10 to 0.
35%, P: 0.005-0.022%, S: 0.005-0.025%
And the temperature: 1620 ~ 1720 ℃. The component of slag is T.
Fe: 8-25%, MnO: 2-8%, CaO: 40-60
%, SiO ₂ : 10 to 20%, P ₂ O ₅ : 1 to 3%, Mg
O: 5 to 8%.

In the example of the present invention, the slag surface of 1 m ² was added to the slag.
Water was sprinkled at 65 liters / min for about 2 minutes. The slag surface area at this time was 6 m ² , and a total of 800 liters of water was sprayed. Slag foaming subsided during watering.
There is almost no forming restraint cost. In Comparative Example 3, foaming was suppressed while adding a slag foaming suppressor, which is a mixture of pulp sludge and slag described in the prior art, to this slag. The sedation time required about 10 minutes, and a total of 1 ton of the foaming suppressing material was required.

[0020]

According to the present invention, it is possible to suppress the forming of slag in a slag pan safely, early, and inexpensively.

[Brief description of drawings]

FIG. 1 is a schematic view of equipment of a sprinkling method of the present invention, in which (a) is a plan view and (b) is a front view.

FIG. 2 is a chart showing the relationship between the watering speed and the slag sedation time of the present invention.

[Explanation of symbols]

 1: Watering 2: Nozzle tip 3: Slag pan 4: Water injection pipe

Front page continued (72) Inventor Keiichi Takayama 12 Nakamachi, Muroran City Nippon Steel Corporation Muroran Works

Claims (2)

[Claims] 1. A method for suppressing the forming of a steelmaking slag, which comprises spraying atomized water onto the surface of the slag in the slag pan when suppressing the forming of the steelmaking slag in the slag pan. 2. The supply speed of the water to be sprayed depends on the slag surface 1
Method according to claim 1, characterized in that it is between 15 l / min and 70 l / min per m ² .