KR100862800B1 - Method for Manufacturing Molten Steel by Converter Refining Process - Google Patents

Abstract

The present invention relates to a converter refining method for preparing molten steel by injecting molten iron as a main raw material and iron ore as an auxiliary raw material into a converter and injecting oxygen toward the molten metal in the converter through an oxygen blowing lance. The present invention provides a method for refining a molten steel which can be dissolved by removing the now attached to the blown lance.

According to the present invention, in the converter refining method of preparing molten steel by injecting molten iron as a main raw material and iron ore and a coolant as a subsidiary material into a converter, and injecting oxygen toward the molten metal in the converter through a lance, a constant amount is applied at a predetermined time interval during the converter refining operation. It is possible to improve the agitation power of slag by repeatedly changing the flow rate of oxygen in the flow range of, and to dissolve and remove the current attached to the lance for oxygen injection by the reaction heat generated by the furnace reaction by dividing the iron ore as an oxygen source. The key point is the method of refining molten steel.

Converter, refining, now, lance, melting, oxygen blowing, iron ore

Description

Method for Manufacturing Molten Steel by Converter Refining Process

1 is a schematic diagram showing a converter coating process

Figure 2 is a schematic diagram showing the current state attached to the upper and lower portions of the oxygen blowing lance, (a) shows the case is now attached to the upper portion of the lance, and (b) is now attached to the lower portion of the lance Indicates case

Figure 3 is a schematic diagram showing a conventional converter blow pattern

Figure 4 is a schematic diagram showing a converter blow pattern for removing the now attached to the top of the lance in accordance with the present invention

Figure 5 is a schematic diagram showing a converter blow pattern for removing the now attached to the bottom of the lance in accordance with the present invention

Explanation of symbols on the main parts of the drawings

One . . . Converter 2. . . Slag 3. . . Oxygen blowing lance

4 . . . Coating material 5. . . now

The present invention relates to a converter refining method for preparing molten steel by injecting molten iron as a main raw material and iron ore as a subsidiary material into a converter and injecting oxygen toward the molten metal in the converter through an oxygen blowing lance. The present invention relates to a method for refining molten steel that can be dissolved by removing the current attached to the lance for oxygen blowing during fresh coating.

In the converter refining process, as shown in FIG. 1, after the last tapping is completed, dolomite or the like is introduced into the slag 2 in the converter 1, and nitrogen is blown through the oxygen blowing lance 3 to perform coating.

The coating method is a method in which a nitrogen jet is generated by blowing nitrogen at a high pressure so that the coating material 4 is attached to the refractory of the converter.

As described above, when the coating material is attached to the converter refractory, a phenomenon occurs that the coating material 4 attached to the refractory is bound to the lance, and the attached material is hard as cement by combining dolomite and slag.

If the coating material is blown while the coating material is attached to the oxygen blowing lance (3) as described above, the iron particles are easily attached to the oxygen blowing lance (3) during the oxidation of the main raw material, as shown in FIG. It forms now on the lance 3.

Fig. 2 (a) shows the current formed on the upper portion of the oxygen blowing lance, and (b) shows the current generated on the lower portion of the oxygen blowing lance.

When the refining operation is carried out in the state where it is attached to the oxygen blowing lance as described above, a lance con which covers the lance hole and serves to prevent the outflow of flame or gas when the lance is raised may be detached. There is a concern, and there is a problem that it is difficult to judge the molten steel temperature and the content of the end point carbon and an operation error occurs.

As a representative method of removing the current attached to the oxygen blowing lance, various auxiliary raw materials are pre-injected before the blow, and the temperature rising during the blow is used, and at the end of the blow, the oxygen blowing lance is lowered by 600 mm and attached to the lance for the oxygen blow. There is a method of dissolving and removing the now and the method of raising the oxygen blowing lance after the completion of the blow to the upper limit and then using the oxygen in the field to wash and remove the now.

In the case of the former method, the nozzle life is reduced due to the lowering of the converter furnace life, the increase in the end point oxygen, and the deterioration of the quality of the steel, and a large amount of inclusions such as pinholes are generated. [P] outbreak occurs, and inadequate goods are caused by excessive input of various subsidiary materials, which are attached to the oxygen blowing lance and are not easily removed and have an unsafe operation.

In addition, in the case of the latter method, there is a problem that the burn and fall disaster of the worker occurs in the process of cleaning the now using oxygen in the field.

The present inventors conducted research and experiments to solve the above-mentioned problems of the conventional method, and based on the results, the present invention proposes the present invention. It improves the agitation power of slag by repeatedly changing the flow rate of oxygen at, and maximizes the furnace reaction by dividing iron ore as an oxygen source, thereby attaching it to the oxygen blowing lance during nitrogen coating by the reaction heat generated by the furnace reaction. The present invention aims to provide a method for refining molten steel that can be dissolved and removed.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

In the converter refining method of manufacturing molten steel by injecting molten iron as a main raw material and iron ore and coolant as a subsidiary material into a converter and blowing oxygen toward the molten metal in the converter through a lance.

Observe the appearance of the lance to observe where it is now attached;

If the position where the now is attached is the top of the lance

The oxygen flow rate to the 54150~59850 Nm ³ / Hr from the time after the start of blowing 9.5~10.5% of the blowing time, at the time at 19-21% to the minimum flow rate of 61~68% 38900~43000Nm ³ / Hr and to have a maximum flow rate of 57900~64000Nm ³ / Hr alternately, and controlled in a time of from 80-89% up to 100% by 52200~57700Nm ³ / Hr,

The iron ore is divided into two or more times at the time of starting the blowing from 19 to 21% to 61 to 68% of the total blowing time; And

If the position where the now is attached is at the bottom of the lance

After the start of oxygen flow blown blow gun at the time in 19-21% of the time to 61~68% 38900~43000Nm ³ / Hr and the flow rate of at least 57900~64000Nm ³ / Hr so as to have a maximum flow rate of the alternately and 80~ From 52% to 57700 Nm ³ / Hr at the time of 89% to 100%, the height from the molten surface to the tip of the lance is controlled at 1.66 to 1.84m at the time of 80 to 89% to 100%. And it relates to a converter refining method of the molten steel, characterized in that the iron ore is divided into two or more times at a time point from 19 to 21% to 61 to 68% of the total time after the start of the blow.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Typically, after the molten steel is blown in the converter and before carrying out the next blow process, the inner wall of the converter is coated for nitrogen spray, which is now attached to the oxygen blowing lance by nitrogen spray.

The present invention relates to a converter refining method for molten steel which can dissolve and remove the present adhered to the oxygen blowing lance during nitrogen splash coating without adversely affecting the quality of molten steel by appropriately controlling the blowing pattern.

In addition, according to the present invention, the blowing pann can be changed more effectively according to the position to which the now is attached.

In the case where it is now attached to the upper portion of the lance, the distance between the molten surface and the lance tip is not particularly limited, and may be controlled as in the conventional method.

If the distance between the molten surface and the lance tip is too short, the scarfing phenomenon of the lance nozzle occurs, and if it is too long, the decarburization reaction of the molten iron is delayed, the goods speed is slowed, and the slope is severely generated. Therefore, the distance between the molten surface and the lance tip is preferably controlled in the range of 1.5 to 2.5 m.

On the other hand, if it is now attached to the lower part of the lance, it can be properly controlled by a conventional method before 80 ~ 89% of the total drilling time after the start of the drilling, and the time from 80 to 89% to 100% of the total drilling time after the start of the drilling. It is preferable to control the height from the molten surface to the tip of the lance at 1.66-1.84m.

If it is now attached to the upper or lower part of the lance, the iron ore (sintered light) is divided into 19-21% to 61-68% of the total drilling time after the start of the drilling.

Since decarburization does not occur sufficiently when the molten steel is converted to less than 19 to 21% of the molten steel, when the iron ore is introduced at this time, the molten iron temperature is lowered and the goods are not sufficiently generated, and 61 to 68% of the blowing time. At the time when the oxygen injection amount is increased, the amount of oxygen injection is increased. Therefore, when the iron ore is charged at this point, the amount of CO ₂ is increased, so that a slope phenomenon occurs. The iron ore is 61-68 at 19-21% of the total time after the start of the drilling. It is preferable to add at a time point up to%.

In the case where the position where the current is attached is the upper part of the lance, it is preferable to control the oxygen flow rate to 54150 to 59850 Nm ³ / Hr at the point of up to 9.5 to 10.5% of the total blowing time after the start of the blow. If the oxygen flow rate is too low at this point, the refining reaction does not occur well. If the oxygen flow rate is too large, molten iron particles are splashed and adhere to the lance.

In the case where the position is now attached to the upper part or the lower part of the lance, the oxygen flow rate is 38900-43000 Nm ³ / Hr and the minimum flow rate is from 19 to 21% to 61 to 68% of the total blowing time after starting the blowing. It is necessary to alternately have a maximum flow rate of ˜64000 Nm ³ / Hr, because if the minimum flow rate is too low, the decarburization reaction is insufficient and the decarburization time is long, and if the maximum flow rate is too large, the decarburization reaction is violently. This is because a sudden increase in the amount of CO ₂ gas causes a slope phenomenon.

In the case where the position where the current is attached is the upper or lower part of the lance, the oxygen flow rate at the time of 80 to 89% to 100% is preferably controlled to 52200 to 57700 Nm ³ / Hr, for this reason. This is because when the flow rate of oxygen is too small, the blowing time is too long, and when too large, the holding time in the furnace atmosphere is too short, so that sufficient removal of the now occurs.

In the present invention, a coolant such as HBI is used two or more times, preferably three times, at a time of 40% to 60% after the start of blowing, which is the point of melting when the lance now melts and is in a red state due to the contact of the molten slag with the lance now. It is preferable to drop the lance now part or to weaken the lance now part by impacting the lance now by splitting.

The total amount of the coolant, such as HBI, is not particularly limited, but is about the amount of the charge carried out in normal operation.

In the present invention, it is preferable to divide the coolant three times by two tons per 100 tons of molten steel.                     

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Example)

[Prior example]

Fluorite: 3.07kg / st, Quicklime: 30.7kg / st, Light Dolomite: 12.3kg / st, Sintered Ore: 27.4kg / st, and Limestone Sludge Cold Pellet: 6.15kg / st After the slag temperature and the molten iron temperature was lowered as much as possible to start the blow, the blow was started, and the blow pattern during the blow was as shown in FIG. 3.

The quicklime was added six times, the light dolomite three times, and the sintered ore four times.

The molten iron used here was charged with C: 4.0%, Si: 0.8%, Mn: 0.30%, P: 0.1%, S: 0.75%, Ti: 0.05%, remaining Fe and other unavoidable impurities.

And in order to prevent the sputtering fluorspar was added more than 1 ton to facilitate the slag goods.

After finishing the molten steel, C: 0.08%, Si: 0.03%, Mn: 0.60%, P: 0.017%, S: 0.004%, sol. Al: 0.60%, remaining Fe and other inevitable impurities.

After removing the lance, the removal rate was 20-30%.

Invention

Fluorite: 0.30kg / st, quicklime: 29.7kg / st, sinter ore: 21.5kg / st, lime cold pellet: 6.15kg / st and HBI (Hot Briquetted Iron): 18.46kg / st , The blowing pattern at the time of blowing the molten iron was as shown in Figs.                     

The molten iron used here is the same as that of the said prior art example.

The fluorspar was added in a batch at 23% of the total time after the start of blowing, quicklime was added in 4 portions between 20-70%, and sintered ore was added in 5 portions between 30-70% and lime cold pellets. Silver was injected at 70% of the time, and HBI was divided into 3 times between 40-70%.

After finishing the molten steel, C: 0.08%, Si: 0.03%, Mn: 0.60%, P: 0.017%, S: 0.004%, sol. Al: 0.60%, remaining Fe and other inevitable impurities.

After removing the lance, the removal rate of the lance was 80-90%.

As described above, the present invention adversely affects the quality of molten steel by appropriately controlling the converter blow pattern and dividing the iron ore at the appropriate time by dissolving and removing the current attached to the lance by the heat of reaction in the furnace and the active stirring of slag and molten iron. Not only does it increase the number of times of lance use, it is easy to manage the lance and the converter can provide a method for refining the converter can be carried out stably and efficiently.

In addition, the present invention is divided into a coolant such as HBI when the iron ore is added, the impact of the lance now with the dissolution of the lance now, to facilitate the natural drop-off due to the impact and self-weight, so that the lance can be removed more efficiently. It is possible to provide a method for refining converters.

Claims (2)

In the converter refining method of manufacturing molten steel by injecting hot briquetted iron (HBI) into the converter as a primary raw material and iron ore and a coolant and blowing oxygen into the molten metal through the lance. Observe the appearance of the lance to observe where it is now attached; If the position where the now is attached is the top of the lance The oxygen flow rate to the 54150~59850 Nm ³ / Hr from the time after the start of blowing 9.5~10.5% of the blowing time, at the time at 19-21% to the minimum flow rate of 61~68% 38900~43000Nm ³ / Hr and to have a maximum flow rate of 57900~64000Nm ³ / Hr alternately, and controlled in a time of from 80-89% up to 100% by 52200~57700Nm ³ / Hr, The iron ore is divided into two or more times at the time of starting the blowing from 19 to 21% to 61 to 68% of the total blowing time; And If the position where the now is attached is at the bottom of the lance After the start of oxygen flow blown blow gun at the time in 19-21% of the time to 61~68% 38900~43000Nm ³ / Hr and the flow rate of at least 57900~64000Nm ³ / Hr so as to have a maximum flow rate of the alternately and 80~ From 52% to 57700 Nm ³ / Hr at the time of 89% to 100%, the height from the molten surface to the tip of the lance is controlled at 1.66 to 1.84m at the time of 80 to 89% to 100%. And the iron ore is divided into two or more times at 19-21% to 61-68% of the total time after the start of the blow. The method for refining a molten steel according to claim 1, wherein HBI is divided into two or more times as a coolant at a time of 40% to 60% of the total time after starting the blowing.

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