JPS5855513A - Process for pretreating molten pig - Google Patents

Abstract

PURPOSE:To prolong the life of a ladle-lining by preventing the erosion loss of lining refractory and to improve the decrease of received pig amount due to the foam generation of slag by the following method in which the molten pig is circulated through a cylindrical body similarly as the circulation method by blowing gas, and simultaneously, some flux is added into the molten pig in the cylindrical body. CONSTITUTION:A cylindrical body 14 is inserted into a molten pig-ladle 2 until its molten pig-exit 17 is dipped near the surface of the molten pig. Inert gas for gas lift is spouted into the molten pig in the cylindrical body 14 from a plural number of gas- spouting ports 16 on the lower and inner surface of the cylindrical body 14. Simultaneously, line and soda-ash etc. from a hopper 18 are added into the molten pig in the cylindrical body 14. Accordingly, the molten pig in a ladle 2 is circulated in the arrow direction and is elevated in the cylindrical body 14, whereby the molten pig is fully agitated by gas buffling and reacts effectively with the charged additive, and then it is caused to flow out from the exit 17. Then if necessary, oxygen gas is blown onto the molten pig from a lance 20. The generated slag does not come in contact with the lining-refractory of the ladle 2 and also foam generation of slag ocurrs only in the cylindrical body. Thus the purpose may be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot metal pretreatment method for subjecting hot metal to preliminary treatments such as Si removal, P removal, S1 removal, and V removal.

In recent years, hot metal has often been subjected to preliminary treatments such as removal of Si, removal of P, removal of S, removal of V, etc., depending on its composition, the type of steel produced, the steelmaking and refining method, etc.

Examples of such pretreatment methods include the injection method shown in Fig. 1, the in-in method shown in Fig. 2, and the GMR method shown in Fig. 3 when preprocessing is performed using a hot metal ladle.
Furthermore, when preliminary treatment is performed using a pig iron mixing car, an injection method shown in FIG. 4 is known.

In the injection method shown in FIG. 1, a lance 4 is inserted from above into hot metal 1 in a hot metal ladle 2 whose upper surface is covered with a lid 3, and through the lance 4 a deSi agent, a deP agent, A de-S agent, a de-V agent, etc. (hereinafter referred to as additives) are blown in together with gas.

In the in-cover method shown in FIG. 2, a rotary blade 6 is provided in hot metal 1 in a hot metal ladle 2 whose upper surface is covered with a hood 5, and the rotary blade 6 is rapidly rotated to cool the hot metal 1. While stirring, additives are introduced into the hot metal 1 from a hot iron or -7.

The gas blowing reflux stirring method (GMR method) shown in FIG. By blowing gas into the hot metal in the riser pipe 8 through the hole 10 provided in the riser pipe 8, the hot metal in the riser pipe 8 is moved upward, and the liquid level of the hot metal 1 provided in the upper part of the riser pipe 8 is lowered. Discharged onto the liquid surface from a plurality of upwardly exposed discharge ports 11,
In this way, the hot metal is circulated and stirred, and at the same time, additives are introduced into the hot metal 1 in the hot metal ladle 2 from the hot metal pipe 7. Incidentally, the riser pipe 8 is rotatably rotated by a rotating device 12, thereby improving processing efficiency.

In the injection method shown in FIG.
The treatment agent is blown in with the gas through the tube.

The problems with the hot metal pretreatment method described above are:
The treatment agent, flux, and generated slag added to the hot metal in the hot metal pot or mixer car are uniformly distributed on the surface of the hot metal, which causes a reaction in the refractory lining of the hot metal pot or mixer car, which shortens its lifespan. is to decrease. Hot metal pots and pig iron mixers are basically used to transport hot metal, so their inner surfaces are lined with highly insulating refractories, and the slag line, pigtail receiving port, and hot water contact areas are lined with highly insulating refractories. Areas that are subject to particularly severe wear and tear are lined with 5in2-At203 series bricks. However, by the above-mentioned preliminary treatment of hot metal, such as deP and deS treatment, 5iO
4Os-based bricks suffer from significant chemical erosion, resulting in a shortened lifespan. For this reason, the application of basic bricks as lining refractories, for example, has been considered, but few examples have been put into practice due to the problem of spalling.

In addition, the method described above can be used to remove P from hot metal, or to remove P and S from hot metal.
When carrying out simultaneous processing of 1. Because of the risk of swelling and overflowing, the amount of pig iron received must be limited to 70 to 80% of the capacity of the hot metal pot or mixing car, which poses a problem that severely limits the processing of large quantities of hot metal. The bubbling of the slag mentioned above can be avoided by deP of the hot metal or by simultaneous deP and S decarburization, since some degree of decarburization is inevitable when carbon-saturated hot metal is oxidized and refined. This is a strange phenomenon.

From the above-mentioned viewpoints, this invention prevents the large linings of hot metal pots and pig iron mixing cars from melting and damage, and therefore has a long lifespan.
To provide a hot metal pretreatment method that does not reduce the amount of pig iron received due to foaming of slag, in which a refining cylinder is immersed over a predetermined length in hot metal in a container, and the inner circumference of the lower end of the cylinder is By spouting inert gas toward the hot metal in the cylinder from a plurality of gas jet ports provided on the surface,
The hot metal in the container is sucked into the cylinder from the lower end opening of the cylinder, and is discharged into the hot metal from a plurality of discharge ports provided on the surface of the immersed part of the cylinder near the liquid level of the hot metal in the container. The method is characterized in that the hot metal in the cylinder is circulated through the cylinder, and an additive is introduced into the hot metal in the cylinder, and the hot metal and the additive are reacted in the cylinder to pre-treat the hot metal. It is something.

Next, the present invention will be explained with reference to examples and drawings.

FIG. 5 shows a schematic cross-sectional view of an example of a device used in the method of the present invention. In the drawing, reference numeral 14 denotes a refining cylinder whose inner surface is lined with refractory material, and the cylinder 14 is vertically inserted into the hot metal ladle 2 from above, and almost the lower half of the cylinder is a hot metal ladle that is covered with a container. It is immersed in hot metal 1 in 2. The cylindrical body 14 is provided with a gas blowing passage 15 in the vertical direction within its peripheral wall, the tip of which communicates with a plurality of gas jet ports 16 provided on the inner circumferential surface of the lower end of the cylindrical body 14 .

Further, a plurality of hot metal discharge ports 17 are provided through the peripheral wall of the cylindrical body 14 near the hot metal liquid level in the container and immersed in the hot metal.

A hot spring 4-18 for introducing additives into the hot metal in the cylinder 14 is provided at the top of the cylinder 14.
A lance insertion port 20 is formed into which a lance 19 or the like for blowing oxygen into the hot metal in the cylindrical body 14 can be freely inserted. The other end of the cylinder 14 is connected to a dust collector (not shown).

When pre-treating hot metal, the cylinder 14 is inserted into the hot metal ladle 2 until the hot metal discharge port 17 is immersed in a portion of the hot metal 1 close to the liquid level, and is passed through the gas blowing passage 15.
An inert gas for gas lift such as Ar gas or N2 gas is ejected from the gas outlet 16 provided on the inner peripheral surface of the lower end of the cylinder 14 toward the hot metal in the cylinder 14, and the hopper 1
From step 8, additives such as lime and soda ash are introduced into the hot metal in the cylinder 14.

As a result, the hot metal 1 in the hot metal ladle 2 is sucked into the cylinder 14 from the lower end opening 14a of the cylinder 14 and rises inside the cylinder 14 due to the gas lift phenomenon, and is sufficiently stirred by gas bubbling. It reacts efficiently with the additive introduced from p4-18, flows out into the hot metal 1 outside the cylinder body 14 from the discharge port 17 close to the hot metal liquid level in the container of the cylinder body 14, and thus the hot metal ladle 2 It circulates inside like an arrow. At this time, if necessary, a lance 19 is inserted into the cylinder body 14 from the lance insertion port 20 provided at the top of the cylinder body 14, and oxygen gas is blown from the lance 19 toward the hot metal 1 in the cylinder body 14. wear.

After the refining is completed in this way, the inert gas jetting from the gas jetting port 16 of the cylinder body 14 is stopped or minimized,
If oxygen gas is being sprayed from the lance 19, the upper lance 19 that has been stopped is pulled up and removed from the cylinder body 14, and the slag suction lance 24 is inserted through the insertion port 20 instead.
is inserted into the cylindrical body 14, and the slag 21 floating on the surface of the cylindrical body 140 is removed by vacuum suction.

FIG. 6 is a process diagram showing an example of the above-mentioned preliminary refining process. The hot metal ladle 2 containing hot metal is transported by a trolley 22.
It is transported to the location where the pre-processing equipment is installed as shown in the same figure (a). Next, the foot 23 installed below the trolley 22 at that position is operated to raise the trolley 22 and lift the cylinder 14.
is inserted into the hot metal ladle 2 on the trolley 22, positioned so that the gas jet port 16 and the hot metal discharge port 17 of the cylinder body 14 are immersed in the hot metal 1 in the hot metal ladle 2, and the lance 19 is inserted into the cylinder. It is inserted into the body 14 and refined by the method described above, as shown in FIG.

After the refining is completed, the lance 19 is pulled up and the slag suction lance 24 is inserted in its place to suction the slag 21 floating on the surface of the hot metal inside the cylinder 14, as shown in FIG. When the slag removal is completed in this way, the slag suction lance 24 is pulled up as shown in FIG.
is lowered to the ground and moved to the next process.

When hot metal is pre-treated by the above-described method of the present invention, all the pre-treatment is carried out inside the cylinder 14, and the hot metal in the hot metal ladle 2 is circulated through the cylinder 14, and the generated slag 21 is Since they float only on the surface of the hot metal in the cylinder 14 and do not come into direct contact with the refractory lining of the hot metal ladle 2, the refractory lining of the hot metal ladle 2 is not damaged by slag or flux. Note that for the large resistant part of the cylinder 14, a refractory material with high corrosion resistance against slag and flux may be used, and if it is damaged by melting, only this part may be replaced.

In addition, since the bubbling phenomenon of slag that occurs during refining occurs only within the cylinder 14, the upper space of the cylinder 14 is designed to have a length or diameter that corresponds to the length or diameter of the cylinder 14, so that the bubbling takes place therein. This can be done by making the area large enough to accommodate Although the level of the hot metal in the hot metal ladle 2 rises slightly due to the hold-up volume due to the immersion of the cylinder 14 and the blowing of gas for gas lift propulsion, the decrease in the amount of pig iron received is almost negligible. be.

Next, the present invention will be explained using examples together with conventional examples.

Example A refining cylinder with a diameter of 1.5 m according to the present invention was inserted into a hot metal ladle having a capacity of 2 oot containing hot metal.
5 m long, and N2 was used as a gas lift gas.
Gas for 400 Nrr? By feeding the hot metal at a flow rate of /H, the hot metal in the hot metal ladle is circulated through the cylinder, and 3.2 tons of soda ash is added to the hot metal in the cylinder, and
1400 Nm' of oxygen was blown into the hot metal inside the cylinder. The amount of hot metal treated at this time was 198 tons, and the component composition and temperature of the hot metal before and after treatment are as shown in Table 1.

Table 1 Conventional Example A lance was immersed to a depth of 32F+ by the injection method into a hot metal pot with a capacity of 200 tons containing hot metal, and 3.2 tons of soda ash was blown from the tip with N2 gas at a flow rate of 40ONn//H. 2 toward the surface of the hot metal.
A total of 1400 Nrr from the supplementary lance of the book? of oxygen was injected. The amount of hot metal treated at this time was 130 tons, and the component composition and temperature of the hot metal before and after treatment are as shown in Table 2.

As is clear from the above, the conventional example A.
When refining is carried out by the surface extraction method, the capacity is 2
Only 130 tons of hot metal could be processed with a hot metal ladle of 0.00 tons, but when refining was carried out according to this invention, 198 tons of hot metal could be processed with the same capacity hot metal ladle.

Although the above-mentioned embodiment describes the case of treating hot metal in a hot metal ladle, it goes without saying that the same method can be used to treat hot metal in a pig iron mixing car.

As described above, according to the method of the present invention, when pre-treating hot metal in a hot metal ladle or a hot metal mixer car, the lining refractory is prevented from melting and its life is extended, and the bubbling of slag is prevented. The excellent effect of efficiently processing a large amount of hot metal is brought about without decreasing the sensitivity.

[Brief explanation of drawings]

1 to 4 are explanatory diagrams of a conventional pretreatment method, FIG. 5 is a schematic cross-sectional view showing an example of an apparatus used in the method of the present invention, and FIG. 6 is a process diagram of the method of the present invention. In the drawings: 1...Hot metal, 2...Hot metal pot 4...U/S, 13
...Pig iron mixing car, 14...Refining cylinder, 15...Gas blowing passage, 16...Gas jet port, 17...Hot metal discharge port, 18...Hotsuno*, 19... Lance, 20...
・W/S insertion port, 21...Slug, 22...Dolly,
23...Lift, 24...Lance for slag suction. Applicant Nippon Kokan Co., Ltd. Agent Keitabe Tsutsumi (and 1 other person) Funeral map 1 City map 2 %3 map

Claims (1)

[Claims] A refining cylinder is immersed for a predetermined length into hot metal in a container, and an inert gas is directed toward the hot metal in the cylinder from a number of gas spouts provided on the inner peripheral surface of the lower end of the cylinder. By spouting out hot metal, the hot metal in the container is sucked into the cylinder from the lower end opening of the cylinder, and the hot metal is drawn into the cylinder from a plurality of discharge ports provided on the circumference of the immersed part of the cylinder near the liquid surface of the cylinder. The hot metal in the container is thus refluxed through the cylindrical body, and additives are introduced into the molten metal in the cylindrical body, and the molten metal and additives are reacted in the cylindrical body to prepare hot metal. A method for preliminary treatment of hot metal, characterized by carrying out treatment.