JPH02118011A - Foaming prevention agent for castbed desiliconization - Google Patents

Abstract

PURPOSE:To improve the flowability of a foaming inhibitor, to enhance the foaming preventing effect and to reduce the cost by using blast furnace ashes as the foaming inhibitor. CONSTITUTION:Blast furnace ashes, blast furnace ashes blended with waste debris or blast furnace ashes blended with water are used as a foaming inhibitor used in combination with a desiliconizing agent when molten pig iron is desiliconized in a casting bed. The blast furnace ashes and water debris are discharged as wastes from a blast furnace in conventional operation and are inexpensive. Since the foaming inhibitor has high bulk specific gravity and falls through a slag layer, ventholes for allowing gas causing foaming to escape are pierced in the slag layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a foaming inhibitor used in the desiliconization treatment of hot metal.

[Background Art] In recent years, there has been a strong demand for improving the quality of hot metal due to the demand for manufacturing high-grade steel in the steel manufacturing process and reducing refining costs.

For this reason, a desiliconization agent is added to the molten iron to perform desiliconization treatment. Methods for performing the desiliconization treatment include an overlay method in which a desiliconizing agent is charged onto the surface of hot metal, and an injection method in which a desiliconizing agent is blown into the hot metal together with a carrier gas. Among these, the injection method requires a carrier gas supply stage Oi3,
The superposition method is used as a simple method. As the desiliconizing agent, readily available factory-generated iron oxides such as mill scale or powdered sintered ore are used. The use of desiliconizing agents tends to cause slag foaming, but when this foaming increases, the amount of hot metal charged into the hot metal ladle decreases.
Foaming inhibitors are used in conjunction with desiliconizing agents to avoid an increase in the number of pig iron receiving operations or a shortage of hot metal pots.

[Problems to be Solved by the Invention] However, conventional antifoaming agents are expensive and the antifoaming effect is not sufficiently satisfactory.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an anti-foaming agent that is low in cost and has an excellent anti-foaming effect.

[Means and effects for solving the problem] The foaming inhibitor according to the present invention is a foaming inhibitor used together with a desiliconizing agent in the desiliconization of a cast bed of hot metal, and includes blast furnace ash and blast furnace ash containing waste slag. It is characterized by being made of blast furnace ash or blast furnace ash containing moisture.

Blast furnace ash or waste slag is produced as waste material from normal blast furnace operations, and the cost is extremely low.Furthermore, the anti-ohming agent of the present invention has a higher bulk specific gravity than conventional foaming preventive agents, and can pass through the slag layer. Since it falls downward, it has the effect of creating a gas vent in the slag layer as a way to vent the gas that causes forming.

The waste pot is the used mat material used to close the blast furnace tap hole, and the blast furnace ash is dust separated from the blast furnace gas by a dust catcher.

[Example] An example of the present invention will be described while comparing it with a conventional example. Slags that are prone to foaming have the following characteristics: 1) Poor fluidity, 2) Low basicity, and 2) High melting point. Therefore, anti-foaming agents contain carbonaceous material as a heating element to improve fluidity, MgO to increase basicity, and fluorite or lime containing F to lower melting point. is needed. Conventional antifoaming agents focus on improving fluidity.

In addition to improving the properties described in ■, ■, and ■ above, this book also explains that it is important to create gas vents to prevent forming, since the gas generated inside the slag rises and can be easily extracted from the slag surface. The inventors discovered this as a result of various tests. Based on this idea, we developed an anti-foaming agent that not only has the above-mentioned functions necessary for an anti-foaming agent but also has a gas vent. Considering the cost, we investigated using blast furnace ash or waste bottlings.

Figure 1 shows the relationship between the amount of forming inhibitor used and the amount of pig iron received according to this example. In this figure, the amount of pig iron received on the vertical axis is 25
0t is wax, which is 100% of the received pig iron amount, and 220t is the lower limit, and if it is less than this, problems will arise in the operation of the hot metal pot and other problems as described above. In this example, three types of anti-foaming agents were used. That is, I: Blast furnace ash alone, ■: Blast furnace ash containing 20% moisture, ■: Blast furnace ash mixed with 10% waste bottlings.
Three graphs corresponding to n, I[[ and a graph using a conventional foaming inhibitor are shown in the figure.

In addition, this figure was obtained assuming that the St content in the hot metal before and after desiliconization was 0.28% and 0.15%, respectively, and the amount of foaming inhibitors I, II, and H used above and the average acceptance were calculated. The amount of iron is shown in Table 1.

According to Figure 1 or Table 1 of Table 1, the amount of use of only blast furnace ash (■) is slightly larger than that of the conventional example, and no functional effect is observed. If the conventional example is 1, then the weight is about 0.3 for the same weight, so it can be said that it is effective in this respect. In examples n and m, the effect of creating gas vents due to the increase in bulk specific gravity due to the addition of water or waste bottling was observed, and this combined with the cost reduction showed a remarkable effect compared to the conventional example. ing.

[Effects of the Invention] According to the present invention, the anti-foaming agent is blast furnace ash or the same containing waste slag or water.
Excellent foaming prevention effect or cost reduction 6

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the amount of pig iron received and the amount of forming inhibitor used.

Claims (1)

[Claims] An anti-foaming agent used together with a desiliconizing agent in the desiliconization of a cast bed of hot metal, characterized by being made of blast furnace ash, blast furnace ash containing waste slag, or blast furnace ash containing moisture. Foaming prevention agent.