JPS619510A - Method for desiliconizing molten iron - Google Patents

Abstract

PURPOSE:To accelerate a desiliconization reaction by a placing an agitating pipe for producing turbulence in molten iron at a molten iron dropping hole at the end of an iron discharging spout so as to mix and agitate a desiliconizing agent added to molten iron. CONSTITUTION:A desiliconizing agent 9 is added to a flow of molten iron 5 in an iron discharging spout 3 fitted to a blast furnace 1, and the molten iron 5 contg. the added agent 9 is passed through an agitating pipe 10 placed at a molten iron dropping hole at the end of the spout 3 to mix the molten iron 5 with the agent 9 and to agitate them. Thus, the desiliconizing agent 9 is well agitated, so a desiliconization reaction in a torpedo car 7 is accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for desiliconizing hot metal tapped from a blast furnace in a blast furnace cast bed.

Conventional technology and its problems The composition of hot metal tapped from a blast furnace greatly affects the refining efficiency and quality of steel in the next steelmaking process. Various hot metal pretreatment methods are appropriately adopted depending on the chemical composition and the type of steel produced.

As is well known, hot metal pretreatment methods include desulfurization, dephosphorization,
Desiliconization, etc., is carried out using blast furnace casthouses, hot metal ladles,
It is carried out using torpedo cars, etc.

In this hot metal pretreatment, desiliconization treatment is performed before desulfurization and dephosphorization, but recently a trough desiliconization method is often used in which desiliconization treatment is performed in a blast furnace casthouse, that is, in the tapping process.

For example, as known from Special Publication No. 58-56723,
A method is known in which a desiliconizing agent is added to hot metal in a tap culvert and the natural mixing of the hot metal as it flows is used to desiliconize the hot metal. However, the desiliconizing agent added to the hot metal flowing in the tap culvert tends to flow while floating on top of the molten metal, so the natural mixing described above does not result in sufficient desiliconization in the tap culvert, and in reality, the molten metal is torpedoed. The hot metal and the desiliconizing agent are mixed and stirred by the energy μ falling on the iron. The hot metal and desiliconizing agent are mixed and stirred after they fall into the torpedo. For this reason, in the method of adding a desiliconizing agent to the hot metal in the tap runner, the mixing state of the desiliconizing agent and the hot metal in the torpedo is unstable due to the tapping speed and the unit of desiliconizing agent.
The drawback was that the desiliconization efficiency varied.

Purpose of the Invention The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology, and its purpose is to propose a method for desiliconizing hot metal that can effectively desiliconize hot metal in a blast furnace cast bed. It is something.

Composition of the Invention A method for desiliconizing hot metal according to the present invention is a method for desiliconizing hot metal by adding a desiliconizing agent to the flow of hot metal in a blast furnace tap water, in which the hot metal is swirled into a hot metal falling port at the end of the tap water. The method is characterized in that a stirring cylinder is provided for the purpose of mixing and stirring the hot metal and the desiliconizing agent by passing the hot metal through the stirring cylinder.

The method of this invention will be explained in detail below.

Figure 1 is an explanatory diagram showing a general method for desiliconizing a blast furnace castbed. Hot metal (5) is discharged from the taphole (2) of the blast furnace (1), and the hot metal (5) is installed in the taphole (3). The slag (8) is separated in the skip (4), and the separated slag is sent to the slag outlet (6).
The hot metal (5) passes through the skip (4) and reaches the torpedo (7), but during the tapping process, for example, the hot metal (5) flows through the tap hole (3) on the downstream side of the skip (4). When the desiliconizing agent (9) is added to the hot metal (5), the added desiliconizing agent remains suspended on the hot metal (5) and flows into the tapping sluice (
3), and in the conventional method, it falls directly into the torpedo (7), where the hot metal and the desiliconizing agent are mixed and stirred. That is, in the method of mixing and stirring the hot metal and the desiliconizing agent only by the falling energy of the hot metal, the desiliconizing efficiency varies depending on the tapping speed and the like as described above.

Therefore, this invention attempts to improve the desiliconization efficiency by further promoting the desiliconization reaction by mixing the hot metal and the desiliconizing agent before it falls into the torpedo (7). The method used was to create a vortex in the hot metal at the end of the tap runner, that is, at the droplet of the hot metal, and mix the hot metal with the desiliconizing agent.

That is, in the method of this invention, as shown in an embodiment in FIG. The feature is that hot metal and desiliconizing agent are mixed and stirred in a cylinder and allowed to fall into a torpedo.■ is a fixing metal fitting.

The structure of the stirring cylinder (IG) is to turn the hot metal into a vortex.
As shown in the figure and Fig. 4, the structure has a structure in which a plurality of baffle plates (10-2) are protruded from the inner circumferential wall of a cylinder (10-1) at intervals in the height direction and shifted by 90 degrees. It has become. However, the structure of the stirring cylinder shown here is just an example, and is not limited thereto. The material of the trench is not particularly limited, but ceramic or the like can be used.

Effects of the invention As mentioned above, a stirring cylinder (1
0), the hot metal (
5) is turned into a vortex by the action of a plurality of baffle plates (10-2) provided on the inner wall of the cylinder when passing through the stirring cylinder tIO),
The desiliconizing agent (9), which was added during the tapping process and flowed while floating on the hot metal, is thoroughly mixed and stirred in this stirring cylinder and falls into the torpedo (7). Furthermore, the falling energy of the hot metal further mixes and stirs the hot metal and the desiliconizing agent, thereby promoting the desiliconizing reaction within the torpedo (7).

Therefore, according to the method of this invention, the hot metal and the desiliconizing agent are sufficiently mixed and stirred at the hot metal falling port of the tap runner and fall into the torpedo, so that the mixing and stirring effect due to the falling energy of the melt gun is also added to the desiliconizing agent. The reaction is promoted and the desiliconization efficiency is improved.

Example Hot metal having the components shown in Table 1 extracted from a blast furnace (1
At 510℃, 5 tan/min), 201'f/T of desiliconizing agent (sintered powder with an average particle size of 5) was added on the taper, and the structure shown in the drawing was added at the part where it fell from the taper to the torpedo car. Hot metal and a desiliconizing agent were mixed in a ceramic stirring cylinder and dropped into a torpedo for desiliconization. Note that the stirring cylinder used (d diameter 1000 m.

A cylinder with a height of 1600+m and a thickness of 100m, and a thickness of 1
Four baffle plates of 00 votes were used, which were provided at intervals of 200 votes and shifted by 90 degrees in the height direction.

The relationship between the unit consumption of the desiliconizing agent and the amount of desiliconization j [sl] in this example is shown in FIG. 5 in comparison with the conventional method of desiliconizing without a stirring cylinder.

From the results shown in FIG. 5, it can be seen that in the conventional method, the desiliconization efficiency varies greatly around 6096, whereas in the method of the present invention, the desiliconization efficiency improves to 80%, and the dispersion is very small.

Table 1 Components of hot metal before desiliconization (%) As is clear from the above examples, according to the method of this invention, the desiliconization efficiency of hot metal can be improved by simple means, and the variation is also reduced. , a large amount of hot metal can be stably desiliconized, and the precision of [Si] control after treatment is also improved.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a general blast furnace casthouse desiliconization method, Figure 2
The figure is an explanatory diagram showing one embodiment of the present invention, Figure 3 is a plan view showing a stirring cylinder in this invention, and Figure 4 is "s3 Figure IV".
FIG. 5, which is a vertical cross-sectional view taken along the line -IV, is a chart showing the relationship between the basic unit of the desiliconizing agent and the amount of desiliconizing agent in an example of the present invention. 1... blast furnace, 2... taphole, 3... taphole, 4... skimmer, 5... hot metal, 6... slag discharge port, 7... ...Torpedo, 8...Slag, 9.
... Desiliconizing agent, 10... Stirring cylinder, 10-1...
Cylinder, 10-2...Baffle plate. Applicant: Sumitomo Metal Industries, Ltd. Figure 1 Figure 12 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In a method of desiliconizing by adding a desiliconizing agent to the hot metal flow in the tap hole of a blast furnace, a stirring tube is provided at the hot metal falling port at the end of the tap hole to turn the hot metal into a vortex, and the hot metal flows through the inside of the stirring tube. A method for desiliconizing hot metal, characterized by mixing and stirring hot metal and a desiliconizing agent by stirring.