JPS599117A - Method and device for removing slag in oxygen steel making converter - Google Patents

Abstract

PURPOSE:To improve the yield of iron, by flowing slag once into an auxiliary vessel to increase the layer thickness of the slag and to make the skimming easy and returning metal again to a converter, in the stage of skimming. CONSTITUTION:A vessel 2 which is opened at the top and has an axial center intersecting approximately orthogonally with the axial center of the furnace 1 is stuck in the port part of a converter 1 by bringing the opened surface at the top thereof into contact with the edge on the counter tapping side of the port 6 of the furnace 1. The furnace 1 is first tilted to admit the dephosphorized slag floating on the bath surface of the molten iron 3 in the furnace 1 into the auxiliary vessel 2. Since the depth of the slag 4 in the vessel 2 is large, the slag can be easily ladled away by a siphon type slag remover or the like. If the furnace 1 is returned perpendicularly thereafter the iron 3 flowed out into the vessel 2 is returned again into the furnace 1. The successing oxidation refining is thus started immediately, and the loss of the iron 3 in the stage of skimming of the converter 1 is reduced considerably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing steel from molten pig iron and scrap.
In the refining process of D converter, OBM/Q-BOP converter, top-bottom blowing combined converter, etc., molten pig iron and scrap are loaded into the converter. In the process of producing molten steel by adding gaseous oxygen and auxiliary materials such as quicklime, dolomite, and fluorite, molten slag is produced on the surface of the iron bath. Impurities contained in the pig iron and scrap, especially phosphorus and sulfur, migrate into the molten slag. Therefore, during the converter refining process, it becomes necessary to remove slag containing impurities, add new auxiliary materials, and perform blowing again. Particularly in the case of normal oxidation refining, dephosphorization progresses in the relatively early stage 1 of blowing. If blowing continues while the slag at this stage is kept in the furnace, as the steel bath temperature increases,
A phenomenon is observed in which phosphorus, which has once migrated into the slag, returns to the molten steel. This is extremely unfavorable in terms of blowing efficiency. Such slag should be promptly discharged from the converter.

Conventionally, the method for removing slag from a converter was carried out as follows. In other words, from the converter-like furnace state after dephosphorization blowing, the furnace is tilted toward the charging side until the slag flows out naturally, and if the slag has high fluidity, it is allowed to flow naturally and the slag flows. In cases where the slag was poor, a scraper such as a clarifier was used to scrape the slag floating on the bath surface from the inside of the converter to the furnace mouth, and then discharge the slag from the furnace mouth as well.

In these slag removal methods, since the slag layer is thin when the converter is tilted, metal inevitably flows out together with the slag, which significantly impedes economic efficiency.

An object of the present invention is to provide a slag removal method that eliminates the above-mentioned drawbacks and improves the quality of iron slag [7].

The biggest cause of metal leakage is that when the converter is tilted, the surface area of the iron bath is wide and the slag layer is thinly spread over the bath surface.If you try to remove this, metal will inevitably flow out as well. It depends on what you end up doing.

Preventing metal outflow is achieved by increasing the slag layer thickness to facilitate slag removal and returning the metal to the converter. The present invention involves tilting the converter from a furnace-type state to the charging side when removing slag from an oxygen steelmaking furnace, allowing the slag floating on the surface of the molten iron bath to flow into an auxiliary container, and then from the auxiliary container. This slag removal method is characterized in that only slag is removed, the converter is then brought into a furnace-type state, and the molten iron remaining in the auxiliary container is returned to the converter.

FIG. 1 is an explanatory diagram of the method of the present invention, and is a longitudinal cross-sectional view of the converter during tilting. FIG. 1 shows a state in which the converter 1 is tilted and the dephosphorization slag 4 floating on the bath surface of the molten iron 3 in the converter flows into the auxiliary container 2.

Since the slag 4 in the auxiliary container 2 is deep, it can be easily pumped out and removed using, for example, a knife-on type slag removal device. That is, one end of an iron conduit lined with a refractory material is immersed in the auxiliary container 2, and the pressure inside the conduit is temporarily reduced using a vacuum pump or the like, so that the Zyphon effect is applied to the conduit. By doing so, the slag in the auxiliary container can be sucked up into the conduit and continuously discharged from the other end of the conduit into a portable container such as a slugbot.

Of course, only the slag 4 in the auxiliary container can be removed by scraping out with a clarifier or the like.

After the slag in the auxiliary container 2 is removed, the converter is returned to its original position, and the molten iron 2 that has flowed into the auxiliary container 2 is returned to the converter.

In this way, the subsequent oxidation refining is started immediately, the loss of molten iron during slag removal from the converter can be significantly reduced, and molten steel of a desired composition can be blown with a good yield.

Next, FIGS. 2 and 3 show an embodiment of the invention of an apparatus directly used for carrying out the above-described invention. That is, in an oxygen steelmaking converter, the converter 1 is placed at the furnace mouth of the converter.
An open top container 2 having an axis substantially perpendicular to the axis of
This is an oxygen steelmaking converter characterized in that the two open faces of the converter J are brought into contact with the opposite side edge of the furnace opening 6 of the converter J and are fixed together.

Figure 2 (a) ij:, A-A arrow view in Figure 1, Figure 2 (
b) is a view from arrow 13-13 in Fig. 1, and the container 2 is a container lined with refractory material, and is removably attached to the conventional converter 1, just like the jaws of the converter. Can be attached.

The internal volume of this container after lining is 30.
It takes 1 minute at the first step.

In FIG. 2(b), the odor C15 indicates the tapped steel 1-1, and the upper edge of the container 21-, j is in contact with the periphery of the unrolled steel fI11 of the furnace [ ] 6 of the converter 1. Figure 3 shows another embodiment, in which (a) is a longitudinal sectional view, (b)
is the fourth view of arrow C-C in (a). In the embodiment shown in FIG. 3, a container 2 is attached to the converter 1 so as to form a gourd-like shape. In this case as well, the slag receiver of the container 2 is provided on the side opposite to the exposed steel, and the internal volume of the container 2 after being lined with fireworks is sufficient to be 30 inches or less of the converter internal volume.

When recovering converter gas without combustion, it is easy to shut off the gap between the converter mouth and the third cylinder, which is advantageous in terms of recovery efficiency.

With the device of the present invention, it is possible to temporarily store the converter slag, increase the slag depth, easily separate the slag and molten iron, and remove the slag, thereby significantly reducing the loss of molten #I iron during slag removal. can be reduced.

The method and apparatus Iri of the present invention are not only used for intermediate removal of slag after dephosphorization and blowing using blast furnace hot metal as the main raw material, but also for preliminary treatment of desulfurization or desiliconization of blast furnace hot metal using a converter. It can be used as a method and device for removing slag.

In particular, even in the production of steel containing expensive metals such as stainless steel, the method of the present invention can be used to remove the acid slag after the reduction process, and then add flux for desulfurization to make it economical. Desulfurization treatment can be performed.In this case, the apparatus of the present invention is not a converter, but an AOD furnace, a CLU furnace, etc., with a container attached to it.

Example 51 Blowing was carried out using a converter equipped with the container 2 shown in FIG. 2.

Ingredients are 4.5%C1022%Si, 0.341Mn
.

Charge 4.73 of hot metal with a temperature of 1324℃ at 0.129cmP, 0.006cmS, and mix-fired dolomite) 23kg/hot metal t1 fluorite 4.9ky/hot metal t1 ore and scale A.37
．． 6kg/hot metal t1 gaseous oxygen 11.3Nff//hot metal t
The blowing was performed using the.

The slag on the bath surface was once collected in the container 2 and then mechanically scraped out using a clay char. The amount of slag sludge finally removed outside the converter was 3]-, 2k17/t of hot metal. On the other hand, the amount of molten iron that flowed out of the converter along with the slag was 1.5 kg/1 hot metal as a result of magnetic separation weighing.Furthermore, the hot metal composition and temperature at the intermediate converter were 3.25%C10, I9%Mn.
, 0.011. %P10. O05%S, 1370°C, and sufficient dephosphorization was progressing.

According to conventional experience, in the case of the same conventional converter, the amount of hot metal flowing out of the converter during intermediate slag removal with the same blowing pattern is 8 kg/t of hot metal.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of the converter during tilting of the converter, Figure 2 (a)
, (b) are the A-A arrow view and B- of the converter in Fig. 1, respectively.
13, and FIGS. 3(a) and 3(b) are a vertical cross-sectional view of another converter and a view taken along the line C-C in FIG. 3... Molten iron 4... Slag 5... Steel tapping port 6... Furnace ['' Patent Applicant Kawasaki Steel Corporation Agent Patent Attorney Yoshio Kosugi Figures 1-2

Claims (1)

[Claims] 1. When removing slag from an oxygen steelmaking converter, the converter is tilted from the furnace-type state to the charging side, and the slag floating on the surface of the molten iron bath flows into an auxiliary container, A method for removing slag from an oxygen steelmaking converter, comprising: then removing only slag from the auxiliary container, then returning the converter to a furnace-type state, and returning the molten iron remaining in the auxiliary container to the converter. 2. In an oxygen steelmaking converter, an open-top container having an axis substantially perpendicular to the converter axis is installed at the mouth of the converter, and the open surface and the side edge of the exposed steel at the mouth of the converter are connected to each other. An oxygen steelmaking converter characterized by abutting and fixing dowels.