JPS59173213A - Desiliconization of hot metal - Google Patents

Abstract

PURPOSE:To effectively carry out desiliconization, by a method wherein hot metal is added with a required amount of desiliconizing agents according to the amount of hot metal to be tapped and the silicon content and thereafter added with a required amount of slag forming inhibitors according to the adding amount of desiliconizing agents. CONSTITUTION:The silicon content of hot metal tapped from blast furnace is continuously on by a fixed time interval measured and at the same time the tapped amount of hot metal is measured. Then, the hot metal is added with a required amount of desiliconizing agents according to the tapped amount of pig iron and the silicon content of hot metal. Thereafter, the hot metal is added with a required amount of slag forming inhibitors according to the added amount of desiliconizing agents.

Description

[Detailed description of the invention] The present invention relates to a method for desiliconizing hot metal.

Conventionally, a method of adding a desiliconizing agent such as mill scale to hot metal flowing through a hot metal gutter installed on the V1 floor of a blast furnace is known as a desiliconizing method to reduce the amount of silica during abrasion.

However, if a desiliconizing agent such as mill scale is simply added to the hot metal flow, the amount of iron oxide to be supplied is limited due to thick slag forming in the pig iron receiving pan.
Water rehydration was used to reduce the amount of mineral content after desiliconization to about 0.20% at most.

This is because the mixture of the desiliconizing agent and the hot metal is opaque.
This is due to the low reaction efficiency of Kohl et al.

On the other hand, in order to perform dephosphorization and desulfurization using soda ash etc.
It is desirable that the silicon content is 0.10% or less.

Therefore, in the desiliconization method described above, it is difficult to dephosphorize and desulfurize hot metal using soda ash.

Therefore, there is a method in which a desiliconizing agent such as mill scale is projected into the flow of hot metal to promote the reaction between the desiliconizing agent and the bath pig iron, and a method in which a slag forming agent mainly composed of coke powder is added to the pig iron receiving ladle. etc. have been proposed and have had some success.

However, since the silicon content in hot metal has a wide distribution as shown in Figure 1, the addition of a desiliconizing agent [1] and a slag-forming inhibitor are carried out depending on the slag content. Otherwise, one-layer silicon cannot be formed well. That is, if the addition of the desiliconizing agent -M- is insufficient, the content of Noricon after desiliconization will not reach the target value (for example, below 0.20%), and on the other hand, the content of Noricon in the hot metal will not reach the target value (for example, below 0.20%). %
If the addition of a desiliconizing agent is excessive, the decarburization reaction will proceed at the same time as the desiliconizing reaction, increasing slag forming.To prevent slag forming, it is recommended to use a slag forming inhibitor. It is good to add it to the second one.

Even this arbitrary amount has a certain degree of dignity, and it cannot be added to it unnecessarily.

In view of the above-mentioned aspects, the present invention provides a method for desiliconizing hot metal that can efficiently desiliconize by adding a desiliconizing agent and a slag foaming inhibitor in appropriate amounts. The hot metal that is tapped from the blast furnace is
Continuous notification of recon content (Otsu 1, fixed time interval 4 +
At the same time, the appearance of the hot metal is determined, and a desiliconizing agent is added to the desired portion of the hot metal according to the hot metal tapping area and the content of Noricon in the hot metal. The present invention will be explained in more detail.

A block diagram of the method of this invention is shown in FIG.

4. The content of Noricon in the pig iron can be measured by fluorescent X-ray analysis or the like.

The amount of desiliconizing agent added is adjusted depending on the silicon-containing acid in the hot metal, but Figure 3 shows an example of the amount of mill scale added depending on the silicone content when mill scale is used as a desiliconizing agent. shows.

The method of adding the desiliconizing agent allows the desiliconizing agent to be sufficiently mixed with the hot metal. A desiliconizing agent is projected into the molten iron stream at a constant rate. The so-called projection method is adopted.

The amount of the desiliconizing agent to be added is as shown in FIG. 1, but the amount of the desiliconizing agent to be added needs to be adjusted according to the tapping conditions.

The tapping time varies depending on the blast furnace capacity, tapping time, etc. For example, if the volume of a blast furnace is 2'■.../Ill in
At 8T/min from
0 to 77m1n to 160Ky/min.

The top of the tap is determined at 1tli using the flow rate side.
The amount of iron can be determined by using a load cell method, that is, by placing the pig iron receiving pot on a weighing stand equipped with a load cell and receiving the pig iron.

In this case, since the projection position of the mill scale and the pig iron receiving position are surrounded, it is possible that an error may occur in the input amount of the mill scale.
Since c is constant, the delay in opening side time between the above-mentioned surface positions is as short as about 20 seconds and can be eliminated.

Next, acid 1 will be explained about Examples.

During tapping, by manipulating the tilting price, mill scale projection was started at the same time as piglet receiving started. At the beginning of the mill scale projection, the Noricon analysis value at the previous pigeonhole was 0.36%, and the received kH was 51·/mj, n.The mill scale total was 1301 so/m i.
It was projected into the hot metal flow at n. Thereafter--as the amount of pig iron received changed as shown in FIG. 4--the projection section of the mill scale was changed accordingly, as shown in FIG.

10 minutes after the start of pig iron receiving, the carving button in the pig iron receiving pot was 0.36%. After that, the amount of pig iron received reached the 5th stage.
Since the change was made as shown in the figure, the mill scale projection amount was changed as shown in Figure 5.

Coke powder as a slag foaming prevention agent (bow, tilted)) is continuously added to the hot metal flow at a point 5 m upstream of the river.
li L, ta. Figure 6 shows the change in the amount of coke powder added.

In this way, the 1301' hot metal was desiliconized.

(lq Ill L) The mill scale was 4゛■゛, and the coke was 220K2.

Table 1 shows the @iron components after desiliconization together with the resistant components before desiliconization.

From Table 1 and the amounts of mill scale and coke used, maximum cavity and silicon effect was achieved by using appropriate amounts of desiliconizing agent and slag forming agent.

As explained above, the present invention provides an extremely useful feature in which the maximum desiliconizing effect can be obtained by adding a desiliconizing agent and a slag-forming inhibitor of 1 * 1 to hot metal. effect is brought about.

[Brief explanation of drawings]

Figure 1 is a diagram showing the distribution of molten slag containing sulfuric acid, fig. 2 is a block diagram of the method of the present invention, and fig. Fig. 4 I [and N1, 5 Fig. 1 d: A diagram showing the relationship between the pigeonhole time and the receiving area and mill scale projection scratches. FIG. Representative of Nippon Doppan Co., Ltd. Natsuo Shioya (and 2 others) Fig. 1 Fig. 3 Fig. 2 Pig receiving time (intermediate)

Claims (1)

[Claims] The licon content of the bath pig iron tapped from the blast furnace is measured continuously or at fixed time intervals, and at the same time the amount of hot metal tapped is measured. A desired amount of desiliconizing agent is added to the hot metal according to the amount, and then the power of the desiliconizing agent is increased by 1. A method for desiliconizing hot metal, which is characterized by adding a desired amount of slag forming to the hot metal.