JPH0578724A - Desulfurizing and desiliconizing methods on casting floor in blast furnace - Google Patents

Abstract

PURPOSE:To efficiently progress desulfurizing and desiliconizing reactions in a short time in the pre-treatment for a molten iron. CONSTITUTION:By injecting desiliconizing agent into the molten iron 1 in an molten iron trough 3 and dropping the molten iron into a molten iron tilting trough 5, the desiliconizing reaction is progressed therein. On the other hand, further, by injecting desulfurizing agent to a place where the molten iron 1 is dropped and poured into a molten metal ladle 6, the desulfurizing reaction is progressed under stirring the molten iron 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace cast bed desulfurization desiliconization method for improving the efficiency of desulfurization and desiliconization in the pretreatment of molten pig iron.

[0002]

2. Description of the Related Art As a technique for performing a pretreatment such as desulfurization and desiliconization of hot metal prior to a steelmaking process, Japanese Patent Laid-Open No. 63-19 is known.
In No. 9813, as shown in FIG. 3, while the molten pig iron 1 flowing out from the tap hole 2 provided in the blast furnace wall 2a flows through the molten pig iron gutter 3, the removal of the molten slag 1a mixed by the skinmer 4 is performed. There is disclosed a method in which the pretreatment agent supplied from the hopper 9a is injected by the injection burner lance 9 after that.

[0003]

When the desiliconization treatment of the hot metal 1 is carried out by the above method using the desiliconization agent composed of oxides such as mill scale and iron sand as the pretreatment agent, the following formula 1 is used. As described above, the oxidation reaction of the Si component in the hot metal 1 proceeds.

[0004]

[Equation 1] Si + 2FeO → SiO ₂ + 2Fe

On the other hand, quicklime (CaO) is used as a desulfurizing agent
In the case of performing the desulfurization treatment of, the reaction proceeds by a reduction reaction as shown in the following equation (2).

[0006]

[Equation 2] FeS + CaO + C → CaS + Fe + CO

The reactions represented by the above formulas (1) and (2) are contradictory reactions, one of which is an oxidation reaction and the other of which is a reduction reaction.
Even if both the desiliconizing agent and the desulfurizing agent are used for injection into the same hot metal gutter 3, it is unlikely that these reactions proceed at the same time.

Therefore, one of the pretreatment agents is injected into the hot metal gutter 3 to advance one reaction of desiliconization or desulfurization, and as shown in JP-A-1-165710, after the hot metal is received, the hot metal is used in a torpedo car or the like. It is possible to carry out both desulfurization and desiliconization of the hot metal 1 by transporting it to the pretreatment site and letting the hot metal 1 in the torpedo car proceed with the other reaction.

However, according to the above method, the treatment time becomes long, and therefore the temperature of the hot metal 1 is lowered during the transportation of the hot metal, and the personnel and cost for slag-off increase.

The present invention was devised in view of the above problems of the prior art. The desulfurization and desiliconization reactions of hot metal are independently performed at close positions, so that both reactions can be performed in a short time. The idea is to allow them to proceed separately.

[0011]

Therefore, the blast furnace cast bed desulfurization desiliconization method of the present invention is to blow either one of the desulfurizing agent or the desiliconizing agent into the hot metal tapped from the blast furnace, and then to carry out the hot metal decanting gutter. The basic feature is that the remaining one is blown into the hot metal that is dropped and poured into the hot metal ladle.

[0012]

[Operation] First, one of the above pretreatment agents is blown into tapped hot metal to perform desulfurization or desiliconization using the stirring force of the hot metal obtained when the hot metal is dropped into the hot metal inclined pouring trough. Next, the other pretreatment agent is blown into the place where it is dropped and poured into the hot metal ladle from this tilting gutter so that the stirring action of the hot metal obtained at the time of the fall is used to advance the other pretreatment reaction. Therefore, the desulfurization and desiliconization reactions of the hot metal independently proceed in a short time after the hot metal is poured into the hot metal ladle.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the method of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing an embodiment of the blast furnace casting bed desulfurization / desiliconization method of the present invention.

The hot metal 1 flowing out from the tap hole 2 is guided to the hot metal gutter 3 and flows. At this time, the slag 1a mixed in the hot metal 1 is removed by a skinmer 4. After that, the hot metal 1 flows through the hot metal gutter 3 and flows into the hot metal tilting gutter 5. Further, the tilting gutter 5 guides the hot metal 1 to the upper part of the hot metal ladle 6 having a hot metal receiving capacity of 250 tons, and becomes the waterfall-shaped downflow hot metal 1 which is dropped and poured into the ladle 6. The molten pig iron 1 in the ladle 6 gradually raises the molten metal surface while separating and floating the molten slag 1a.

In this embodiment, a silicidation lance 7 is provided in the upper part of the hot metal gutter 3, and a silicidation agent such as mill scale is projected from the hopper 7a. The desiliconization reaction of the hot metal 1 by the desiliconizing agent [according to the above mathematical expression 1] proceeds when it falls into the hot metal gutter 3 and the hot metal inclined pouring gutter 5. On the other hand, the desulfurization lance 8 is inserted into the hot metal ladle 6 and the desulfurizing agent such as quick lime is put into the hot metal 1 bath deep inside the ladle 6 from the hopper 8a. The desulfurization reaction of the hot metal 1 by the desulfurizing agent [according to the above formula 2] goes deep into the hot metal 1 bath in the ladle 6 and progresses with stirring of the hot metal 1 in the process of rising from there. . That is, hot metal tilting gutter 5 and hot metal ladle 6
Will be used as independent reaction tanks for desiliconization and desulfurization, respectively, and the desiliconization reaction and the desulfurization reaction will be carried out independently and continuously.

The time required for pouring the hot metal 1 into the hot metal ladle 6 is about 30 minutes, and the hot metal 1 ordered in the ladle 6 is full of 25
As soon as it reaches 0 tons, acceptance of hot metal 1 and projection of these desiliconizing agents and desulfurizing agents are stopped. A few minutes after the injection of the hot metal 1 started, the projection of the desiliconizing agent and the desulfurizing agent started and ended in about 20 minutes.

The results of the implementation of the above-described embodiment are shown in Tables 1 and 2 below. Table 1 shows the composition of the components in the hot metal 1 before and after the treatment according to this example, and Table 2 shows the composition of the desiliconizing agent and desulfurizing agent used and the basic unit used. There is.

[0019]

[Table 1] Unit
(%)

[0020]

[Table 2]

From these tables, it can be seen that desiliconization and desulfurization of the hot metal 1 are sufficiently advanced even if the basic unit used of the desiliconizing agent and the desulfurizing agent does not become too large.

On the other hand, when the time required for reaching the converter through these treatments from tapping iron was measured, as shown in FIG. 2, in the present embodiment, the desiliconization and desulfurization reaction proceeded efficiently, and the converter It took about 2 hours to reach. However, it takes about 6 hours in the conventional method of carrying out desiliconization in the pig iron and desulfurization in the hot metal pretreatment site after carrying the torpedo car and then carrying it to the converter. With such shortening of processing time, the temperature dropped during transportation is about 70 ° C,
A heat margin in the converter is generated by the amount of heat reduction suppression, the amount of iron ore directly input is promoted, and a significant cost reduction can be achieved.

[0023]

According to the present invention described in detail above, the desulfurization and desiliconization reactions of hot metal can be independently carried out at the positions close to each other. Therefore, both reactions can be performed separately in a short time. You will be able to proceed. As a result, the temperature drop of the hot metal during transportation of the hot metal is suppressed, and the personnel and cost for slag-off can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a method of desulfurizing and desiliconizing hot metal according to an embodiment of the present invention.

FIG. 2 is a graph showing the time required for transportation from the tapped iron to the converter when each of the present embodiment and the conventional example is carried out.

FIG. 3 is an explanatory diagram showing an example of a conventional hot metal pretreatment method.

[Explanation of symbols]

 1 Hot metal 2 Outlet tap 3 Hot metal gutter 5 Hot metal tilting gutter 6 Hot metal ladle 7 Desiliconization lance 8 Desulfurization lance

Claims (1)

[Claims] 1. The hot metal tapped from the blast furnace is blown with one of a desulfurizing agent and a desiliconizing agent, and then the remaining hot metal is dropped into a hot metal ladle through the hot metal tilting gutter. A method for desulfurizing and desiliconizing a blast-furnace cast bed, which comprises blowing