JPS59185716A - Desiliconizing method of molten iron - Google Patents

Abstract

PURPOSE:To desiliconize efficiently and easily a molten iron by blowing gaseous oxygen from the lower part of a tapping spout directly into the molten iron between the tap hole of a blast furnace and a skimmer of the tapping spout. CONSTITUTION:The molten iron 2 in a blast furnace 1 is tapped through a tap hole 3 onto a tapping spout 4, and while the molten iron flows down in the spout 4, molten slag 5 is separated and floated thereon. The floating slag 5 is discharged from a slag discharging spout 7 provided in proximity to the skimmer 6 provided in the down stream part of the spout 7. On the other hand, the pig iron 8 in which the slag 5 is separated and floated flows down underneath the slag 5. Gaseous oxygen is directly blown through the inside pipe 10 of an oxygen blowing nozzle 9 of the double pipe construction provided in the bottom of the spout 4 into the molten iron 8, by which a desiliconization reaction is accomplished. Inert gas is circulated in the outside cylinder 11 of the nozzle 9 for the purpose of cooling the nozzle 9. The resulted product by the desiliconization reaction is separated and floated from the molten iron 8 and enters the inside of the slag 5. Said product is removed together with the other molten slag through the spout 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently desilicifying hot metal tapped from a blast furnace in a tap trough of a blast furnace.

BACKGROUND ART Conventionally, hot metal tapped from a blast furnace has been subjected to a desiliconization treatment. In other words, as a method for desiliconizing hot metal, iron ore (U'et os) or quicklime (
A method is to introduce a desiliconizing agent such as (Cab), a method to inject chopped iron ore or quicklime into a pig iron mixer using an inert gas as a carrier gas, or a method is to transfer the hot metal to a desiliconizing container. A known method is to blow oxygen gas directly below the surface of the hot metal bath.

However, in the method of injecting the desiliconizing agent from the open side of the tap runner, if the desiliconizing agent is injected upstream of the skinmer of the tap runner, slag exists on the hot metal, so the desiliconizing agent cannot be used. The reaction with hot metal is severely inhibited, resulting in poor desiliconization efficiency, and when a desiliconization agent is introduced downstream of the skinmer, the desiliconization product enters the pig iron mixer, so it must be removed before charging into the converter. There are problems such as the need to remove the desiliconized products beforehand, and the method of transferring the hot metal to a container and directly blowing oxygen gas under the surface of the hot metal bath has good desiliconization efficiency, but it is difficult to remove the desiliconized products by transferring the hot metal to the container However, there were problems such as cumbersome operations such as the need to remove desiliconization products, and there was a lack of efficient and easy methods for desiliconization.

The present inventor has conducted repeated research on a desiliconization method using an oxygen gas injection method, and has made the present invention after recognizing that the objective can be delayed by blowing oxygen gas into the pig iron in the tap culvert.

That is, the present invention is a method for desiliconizing hot metal, in which sludge gas is injected directly into the pig iron on the tap runner from the taphole of a blast furnace to the skinmer of the tap runner to cause a desiliconization reaction.

Next, one embodiment of the present invention will be described based on the accompanying drawings. The drawings are explanatory diagrams showing one embodiment of the present invention.

The hot metal (2) in the blast furnace (1) is tapped from the taphole (3) onto the taphole (4), and while flowing down the taphole (4), slag (5) separates and floats to the surface. The slag is discharged and removed from a slag discharge trough (7) provided close to a skimmer (6) provided downstream of the tap trough (4). On the other hand, the pig iron (8) from which the molten slag (5) has been separated and floated flows down below the molten slag (5). This slag (
Oxygen gas is directly introduced into the separated and floated pig iron (8) from, for example, the inner pipe (10) of the oxygen blowing nozzle (9) with a double pipe structure, which is installed at the bottom of the tap trough (4). Blow to cause a desiliconization reaction.

The outer cylinder αυ of the oxygen blowing nozzle (9) has a nozzle (9)
Circulate an inert gas such as argon or nitrogen for cooling. A desiliconization reaction takes place, and the desiliconized product floats up and separates from the pig iron (8), enters the slag (5), is removed from the slag drain (7) together with other slags, and is removed from the slag. The pig iron flows under the skimmer (6) and flows down the tap trough (4).

In the present invention, oxygen is blown directly into the flowing soft iron (8) through the molten slag (5) separated and floated from the bath pig iron (2), and the blowing position is as described above. In addition to blowing from the bottom side of the tap hole (4), it may also be from the side of the tap hole (4) or from the open side of the tap hole (4). 3) to skinmer (
6) Any point between 6) may be used as long as it is carried out, but it is preferable that the desiliconization product can be sufficiently separated and floated from the pig iron (8) at a pressure of 1.5 Kq/crl G to 2.0 Kq/crl G.
It is preferable to blow in the range of 2 Nm" to 3 Nm" per ton of pig iron.

Using the double oxygen blowing nozzle (9) installed on the bottom side of the tap hole (4) as shown in the figure, the outer pipe (1υ is filled with 0 nitrogen,
2 Nm”/ton of hot metal, flow through the nozzle (
9) While cooling the pressure 2 Ky/crrt 2G 6
Sourium gas was injected into the pig iron (8) at a rate of 2 Nm''/t to remove sulfur from the pig iron, and the following results were obtained.

In the present invention, oxygen gas is directly blown into the pig iron flowing down below the separated and floated slag between the tap hole and the skinmer of the tap runner, so that the desiliconization reaction is completely carried out.
The desiliconization product is removed from the slag along with other sludge, and there is no need to perform a separate desiliconization product removal operation. A significant effect was observed.

[Brief explanation of drawings]

The drawings are explanatory diagrams showing one embodiment of the present invention. (1)...Blast furnace (2)...Hot metal (3)
...Tackle spout (4)...Tackle sluice (5)...
・H slag (6)... skimmer (7)... slag drainage gutter
(8)...Pig iron (9)...Oxygen gas injection nozzle

Claims (1)

[Claims] A method for desiliconization of hot metal characterized by directly injecting oxygen gas from the taphole of a blast furnace into the pig iron on the tappipe from the lower part of the tappipe to cause a desiliconization reaction between the taphole and the skinmer of the tappipe.