KR20040053602A - Desulfurization material injecting method for improving desulfurizing efficiency - Google Patents

Abstract

PURPOSE: A desulfurizer injecting method for improving hot metal desulfurizing efficiency is provided to reduce consumption of desulfurizer and shorten desulfurizing time by maximizing efficiency of reaction of desulfurizer with sulfur during hot metal pre-treating operation. CONSTITUTION: In a method for injecting desulfurizer into hot metal when desulfurizing hot metal, the desulfurizer injecting method for improving hot metal desulfurizing efficiency comprises the processes of forming a pipe line(12) inside an impeller(10) mechanically rotated; injecting powder shaped desulfurizer(14) into hot metal through the pipe line by pressure of nitrogen gas, and injecting lump shaped desulfurizer onto the surface of hot metal at the same time; and desulfurizing hot metal as rotationally agitating hot metal, wherein desulfurizing process is performed by selectively injecting the powder shaped desulfurizer, the lump shaped desulfurizer or both thereof into hot metal according to circumstances.

Description

DESULFURIZATION MATERIAL INJECTING METHOD FOR IMPROVING DESULFURIZING EFFICIENCY

In the present invention, in the steelmaking process of refining molten iron into molten steel, the desulfurization agent reacts with sulfur during the preliminary treatment of the molten iron in a molten iron vessel before refining in a converter to remove sulfur (SULFUR) contained in the molten iron. The present invention relates to a desulfurizer input method for improving the molten iron desulfurization efficiency to reduce the amount of desorbent and shorten the treatment time by maximizing efficiency.

In general, among the desulfurization agents for molten iron produced in the blast furnace is a quicklime-based dehydrating agent, calcium carbide-based desorbent, sodium carbonate-based.

The method of supplying the desorbent so that the desorbent penetrates into the molten iron and reacts with the sulfur is divided into the particle size of the desorbent and injected into the upper part of the molten iron as a mass (lump) and the method of blowing the fine powder into the molten iron. It can be distinguished.

In the case of using a bulk desorbent, as shown in Fig. 1, a mechanical stirring method (KR) is used, which is mainly a KR (Kanvara Reactor) method, in which a bulky lime (1a) is introduced from the top and a refractory impeller (2a) coated on the surface of the molten iron. Stirring the molten iron while immersing and rotating, wherein the sulfur and the quicklime of the molten iron react by the stirring force generated; In the case of using the fine powder desorbent, as shown in FIG. 2, the iron pipe 2b coated with refractory on the surface is immersed in the molten iron, and the fine powder desorbent 1b is penetrated into the molten iron through a strong pressure through the pipe 2b. There is an injection method that reacts with the pressure, and the pressure at the time of injection also plays a role of imparting agitation force to the molten iron.

Usually, the dehydration scheme by quicklime is as follows.

[Scheme]

CaO + [S] + [C] = (CaS) + CO

CaC ₂ + [S] = (CaS) + 2 [C]

The degassing reaction is caused by substitution reaction as in the above equation, and the contact speed between sulfur (S) and desorbent in molten iron dominates the degassing rate, and the movement of sulfur in molten iron is governed by the flow characteristics of molten iron.

In other words, by improving the stirring characteristics of the molten iron can increase the rate of reaction of the molten iron to increase the reaction probability with the desorbing agent to increase the rate of deflow reaction.

However, in the KR dehydration method, the desorbent is fed into the surface of the molten iron in a hopper separately installed at the top, and when desorbent is used, the desorbent is sucked into the duct for sucking dust generated during processing. The particle size of the desorbent is limited to the bulk desorbent, and the desorbent introduced to the upper side is introduced into the molten iron by the vortex of the molten iron caused by the stirring force generated when the impeller is rotated. It can be seen that the higher the rotation speed, the greater the dispersion of the desorbent and the greater the reaction efficiency of the desorbent and the sulfur.

However, because the desorbent mixed by the vortex does not react as fast as the impeller rotates, the desorbent (quick lime) does not contribute to the increase of the desorbent reaction efficiency (Eq. It is difficult to carry out dehydration in a desired range within the treatment time.

In addition, the use of a bulk desorbent reduces the area of reaction with the molten iron relative to the input amount, making it difficult to obtain high efficiency, and the molten iron and slag may overflow out of the processing vessel, and the impeller depth ratio (Equation 2) Since the reaction vessel is extremely poor in the lower part of the vessel because it has to be kept low, there is a problem that there is a reaction stagnation zone in which dehydration does not occur.

On the other hand, the injection method is used to remove the dehydrating agent from the hopper separately installed in the upper portion to the dispenser in the lower portion, pressurize the dispenser with nitrogen, and blow it through the lance immersed in the molten iron and apply the stirring force at the same time. The particle size of the desorbent is limited to the fine powder state, but the self-stirring force of the desorbent is weak in the molten iron, so that the rate of rise to the molten iron is relatively high, and thus the reaction efficiency decreases. The lance life is short, such as cutting off, resulting in poor economic efficiency.

(Equation 1)

(Equation 2)

Sedimentation Depth Ratio (%) = Impeller Depth Depth / Holder Floor Height * 100

The present invention has been made in view of the above-described problems of the prior art as described above, and it has been created to solve this problem. By increasing the time the desorbent stays in the molten iron, it increases the chance of the desorbent to combine with sulfur, thereby reducing the amount of desorbent used by improving the degassing efficiency, and distributing the reaction stagnant zone by eliminating the reaction stagnant zone. The purpose of the present invention is to provide a degreasing agent input method for improving the molten iron desulfurization efficiency to improve the productivity by shortening.

1 is an exemplary view showing a molten iron degassing process by the mechanical stirring using a conventional impeller,

Figure 2 is an exemplary view showing a molten iron degassing process of blowing the fine powder using a conventional lance,

3 is an exemplary cross-sectional view of an impeller with a pipeline formed therein according to the present invention;

Figure 4 is an operating state showing a desorbent input method according to the present invention,

5 and 6 are graphs compared with the existing method according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10 ... impeller 12 ... pipeline

14..Degreaser 20 .... hopper

22 .... Dispenser

The above object of the present invention, in the method of injecting the desorbent during molten iron degassing, forming a pipeline inside the mechanically rotated impeller and blows the powder desorbent under the pressure of nitrogen gas through the pipeline; At the same time, the surface of the molten iron is achieved by providing a desulfurizing agent input method for improving the molten iron desulfurization efficiency, characterized in that the degreasing treatment while stirring the molten iron by the addition of a bulk desorbent.

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

In the method of introducing the desorbent according to the present invention, the bulk desorbent and the fine powder desorbent can be used at the same time or selectively, and the stirring force applied to the molten iron is also used by using an impeller to form a pipeline inside the impeller. The desorbent, which is powdered together with the gas such as N ₂ , is blown and then rotated by the impeller, so that the desorbent added to the ladle is mixed into the molten iron through the vortex and used together with the CaO.

That is, as shown in Figure 3, to form a hollow pipeline 12 in the interior of the impeller 10 causing the stirring force, through the pipeline 12 together with the nitrogen gas as shown in Figure 4 Phosphorus desorbent 14 is to be introduced to facilitate the in-mold mixing of the desorbent 14 by the vortex caused by the impeller (10).

In operation, when the hopper 20 stores the powder desorbent 14 and sends the required amount to the dispenser 22, the dispenser 22 pressurizes with nitrogen to transfer the desorbent 14 to its transfer line. Penetrate into the charter.

At this time, the introduced desorbent 14 is discharged in the downward direction of the processing vessel and the stirring force of the molten iron is also formed downward so that the time for which the fine powder desorbent 14 stays in the molten iron is longer and the disadvantage of KR The reaction congestion zone is eliminated.

In addition, since the impeller 10 is continuously rotating, the deflow agent 14 can be evenly distributed throughout the molten iron, thereby maximizing the deflow efficiency.

On the other hand, on the surface of the molten iron, a mass quicklime, another desulfurizing agent introduced as in KR, causes a continuous reaction with the molten iron by the stirring force by the rotation of the impeller 10, so that the rapid dehydration is performed by these two deflowing actions. The processing time is shortened.

Hereinafter, an Example is described.

EXAMPLE

The molten iron from the blast furnace was carried out using a ladle, which is a transport container and a reaction container, and compared with the conventional charging method and the method according to the invention.

In addition, each condition is shown in Table 1, and the result after a process is shown in Table 2.

The separation of bulk desorbents and fine powder desorbents was carried out at a ratio of 50% to 50% of powder, and sampled and temperature measured at intervals of 3 minutes from the start of treatment to the end of the process. The temperature drop over time was measured.

In addition, to confirm the presence of the stagnant zone, after completion of the dehydration treatment, a separate ladle is poured along the molten iron, and the lance is deposited, followed by a blown of nitrogen for 2 minutes to uniformly mix the molten iron, and then take a sample to perform the dehydration treatment. It was compared with the subsequent sulfur concentration.

The desorbent reaction efficiency ηCaO (%), the dehydration rate, and the desorbent raw unit in Table 2 are calculated by the above-described equations 1 and 3,4, respectively.

(Equation 1)

(Equation 3)

% Withdrawal rate = ([% S] before treatment-[% S] after treatment) / [% S] before treatment * 100

(Equation 4)

Desulfurization unit (kg / t.p) = Desulfurizer input / treatment dose * 100

The desorbent reaction efficiency represents the efficiency of the combined desorbent (in this case, CaO) with the sulfur in the molten iron.

In the results of Table 2, the desorbent reaction efficiency of the method according to the present invention shows a much better result than the conventional KR method or injection method, which means that the means devised in the present invention, that is, the pipeline installed inside the impeller The fine powder desorbent supplied through the blower is blown into the lower side of the processing vessel, and the rotational force of the impeller serves to suppress the rise of the desorbent to the upper portion, thereby promoting the even distribution of the desorbent particles in the molten iron and remaining in the molten iron. This is because it increases the chance of reacting with sulfur because the time is long.

In addition, in the upper part of the molten iron, the bulky desorbent injected into the upper part is swept into the molten iron by the vortex generated in the molten iron by the rotational force of the impeller, so that the entire molten iron is uniformly deflowed from the upper layer to the lower layer. At the same time, it means to solve the reaction stagnant zone, which is a disadvantage of the conventional KR method or the injection method, and the difference between the sulfur concentration measured after dehydration and the molten iron evenly mixed only with nitrogen was measured by the present invention. Almost nothing in the method proves this.

In addition, Figure 5 shows the behavior of the sulfur concentration in the molten iron measured by taking samples at intervals of 3 minutes during the dehydration process, the method according to the present invention usually appears at the completion of the dehydration process at 15 minutes As the sulfur concentration reaches 0.005%, it can reduce desulfurization treatment time by 7 minutes and reduce desulfurizer usage by 30% compared to the existing KR method or injection method.

6 shows the behavior of the molten iron temperature during the dehydration treatment, which is roughly lowered by about 1 ° C. after 1 minute. According to the result of the method according to the present invention, the dehydration treatment is performed after about 15 minutes. As it can be terminated, it is possible to reduce the molten iron temperature drop by 30% compared with the conventional KR method or injection method, and thus it can be seen that the burden of temperature can be reduced in the converter process, which is a post process.

As described in detail above, the desorbent input method according to the present invention can flexibly cope with the supply and demand environment of the bulk and fine powder desorbent compared to the KR method and the injection method, which is a conventional dehydration method, reducing the amount of desorbent used and dewatering treatment It is possible to shorten the time, reduce the temperature drop, and obtain a good dewatering rate, which can greatly reduce the processing cost for the dewatering operation and improve productivity.

Claims (2)

In the method of injecting the desorbing agent during molten iron A pipeline is formed inside the impeller that is mechanically rotated, and through this pipeline, the powder degassing agent is blown under the pressure of nitrogen gas, and a bulk degassing agent is introduced to the surface of the molten iron while the molten iron is rotated and stirred to spin the molten iron. Desulfurizer input method for improving the molten iron desulfurization efficiency, characterized in that. The method of claim 1, The desulfurizing agent is a degreasing agent input method for improving the molten iron desulfurization efficiency, characterized in that the lumped and fine powders are selectively or simultaneously put together according to the situation.