WO2018038508A1 - Method for refining hot metal in convertor - Google Patents

Abstract

A method for refining hot metal in a convertor is disclosed. In one embodiment, the method for refining hot metal in a convertor comprises the steps of: pouring hot metal tapped from a blast furnace into a ladle to transfer the hot metal to a kanvara reactor (KR) facility, and introducing a desulfurizing agent to remove sulfur (S); charging the desulfurized hot metal into a pretreatment converter, and removing silicon (Si) from the hot metal by blowing oxygen into the hot metal; tapping the desiliconized hot metal; and charging the tapped hot metal into a decarburizing converter to remove carbon (C). The hot metal poured into the ladle contains 0.6 to 8.0 wt% of silicon (Si).

Description

Charter refining method in converter

The present invention relates to a molten iron refining method. More specifically, the present invention relates to a molten iron refining method capable of refining molten iron including high silicon (Si).

Consistent steelmaking is the process of refining molten iron produced in the blast furnace in the steelmaking process and producing cast steel through a continuous casting process. Specifically, in the steelmaking process, molten iron is dissolved in a blast furnace to manufacture molten iron, and molten steel is manufactured through a first refining process of removing impurities in molten iron by sequentially performing desulfurization and decarburization on molten iron. After the impurities are removed, the molten steel is moved to the continuous casting process when the fine constituents in the molten steel are adjusted through the secondary refining process. After that, the semi-finished product is formed through a continuous casting process, and is finally manufactured through a final molding process such as rolling.

On the other hand, the converter is a facility for removing impurities in the molten iron produced in the blast furnace, the Tallinn converter is a facility for manufacturing ultra-high quality steel by lowering the phosphorus content in the molten iron as much as possible. In addition, the decarburization furnace is a facility used to lower the concentration of carbon in the molten iron. The converter operation may be carried out in a manner in which the subsidiary material or gas is blown into the molten iron and the molten iron is stirred to promote the reaction between the subsidiary material and the gas and the molten iron.

Background art related to the present invention is disclosed in Korean Unexamined Patent Publication No. 2015-0076252 (2015.07.06. Publication, the name of the invention: method of refining molten iron).

According to one embodiment of the present invention, there is provided a method for refining molten iron in a converter capable of refining molten iron containing high silicon.

According to one embodiment of the present invention, a method for refining molten iron in a converter excellent in molten iron slag removal effect is provided.

According to one embodiment of the present invention, it is to provide a method for refining molten iron in the converter to prevent the slopping phenomenon during the molten iron blown, and excellent operation stability.

According to one embodiment of the present invention, to provide a molten iron refining method in the converter that can prevent the load and damage of the equipment during refining.

According to one embodiment of the present invention, there is provided a method for refining molten iron in an converter having excellent economic efficiency.

One aspect of the present invention relates to a method for molten iron refining in a converter. In one embodiment, the method for refining the molten iron in the converter is to repair the molten iron from the blast furnace in the ladle to move to a KR (Kanvara reactor) facility, by adding a desulfurizing agent to the desulfurization (S) process; Charging the desulfurized molten iron into a pretreatment converter, blowing oxygen by blowing the molten iron, and then treating the molten iron to remove silicon (Si); Tapping the desilicon-treated molten iron; And charging the demelted molten iron into a decarburization converter to process decarburization (C), wherein the molten iron repaired to the ladle includes silicon (Si): 0.6 to 8.0 wt%.

In one embodiment, during the de-silicon (Si) treatment, a sub-material including 10 to 45 kg / t-s of quicklime and 15 to 140 kg / t-s of coolant may be added to the pretreatment converter.

In one embodiment, when the molten iron is blown, the oxygen lance height: 2,300 ~ 2,500mm based on the molten steel surface in the pre-treatment furnace, the blow flow rate: 25,000 ~ 30,000Nm3 / h conditions, and when the molten iron is blown, Quantity: It can blow on 10-25 Nm <3> / ts conditions.

In one embodiment, the silicon (Si) content of the desiliconized molten iron is reduced by 0.2 to 6% by weight based on the silicon (Si) content of the molten iron charged into the pretreatment converter, The temperature may be 1,450-1,600 ° C.

In one embodiment, the tapping may be to tap the molten iron through the tapping hole formed on the outer circumferential surface of the preprocessing converter by tilting the pretreatment converter.

In one embodiment, the decarburized molten iron may include 0.1 wt% to 1.0 wt% of silicon (Si), and may have a temperature of 1,300 to 1,600 ° C.

In one embodiment, the molten iron repaired to the ladle may include 4.0 to 8.0% by weight of silicon (Si).

When applying the molten iron refining method of the present invention, it is possible to produce molten steel by refining molten iron containing high silicon, excellent slag elimination effect of the molten iron, prevents the slapping phenomenon during molten iron drilling, operation stability Excellent, can prevent the load and damage of the equipment during refining, it can be economical.

1 shows a molten iron refining method according to an embodiment of the present invention.

Figure 2 shows a pretreatment converter for the desilicon treatment of the present invention.

Figure 3 shows the tapping of the desilicon treated molten iron according to one embodiment of the present invention.

Figure 4 shows the molten iron refining method of the embodiment according to the present invention.

Figure 5 shows the molten iron refining method of the comparative example for the present invention.

6 is a graph showing a silicon content change of the molten iron according to the molten iron refining process of the embodiment according to the present invention.

7 is a graph showing the temperature change of the molten iron according to the molten iron refining process of the embodiment according to the present invention.

Hereinafter, the present invention will be described in detail. In this case, when it is determined that the detailed description of the related known technology or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The terms to be described below are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators, and the definitions should be made based on the contents throughout the specification for describing the present invention.

Charter refining method in converter

One aspect of the present invention relates to a method for molten iron refining in a converter. 1 shows a method of molten iron refining in a converter according to an embodiment of the present invention. 1, the molten iron refining method (S10) desulfurization step (S20) desilicon step; (S30) tapping step; And (S40) decarburization step. More specifically, the molten iron refining method (S10) is a step of repairing the molten iron from the blast furnace in the ladle to the KR (Kanvara reactor) facility, by adding a desulfurizing agent to the desulfurization (S) process; (S20) charging the desulfurized molten iron into a pretreatment converter, blowing oxygen by blowing molten iron, and then treating the silicon with desilicon (Si); (S30) tapping the desilicon-treated molten iron; And (S40) charging the hot melted molten iron into a decarburization converter to process decarburization (C), wherein the molten iron repaired in the ladle includes silicon (Si): 0.6 to 8.0% by weight.

Hereinafter, the molten iron refining method according to the present invention will be described in detail step by step.

(S10) Desulfurization Step

The step is a step of repairing the molten iron from the blast furnace to the ladle (ladle) to move to the KR (Kanvara reactor) facility, the desulfurizing agent is added to the desulfurization (S) treatment. In an embodiment, the molten iron produced in the blast furnace may be unloaded to a topedo car, and the molten iron may be repaired by ladle in the topedo car to be transferred to a Kanvara reactor (KR) facility.

The desulfurization treatment may be performed by adding a desulfurization agent to a KR facility in which molten iron is loaded, by mechanical stirring with an impeller, floating sulfur (S) into the slag, and removing the slag. In one embodiment the desulfurization agent may comprise quicklime and fluorspar. In one embodiment, sulfur and quicklime contained in the molten iron may be made by a reaction such as the following Chemical Formula 1.

[Formula 1]

CaO + S → CaS + O

In one embodiment, the desulfurization agent may be added at a dose of quicklime (CaO): 10-16 kg / ts and fluorspar (CaF ₂ ): 0.5-1.3 kg / ts. When applying the desulfurization agent of the above conditions, the desulfurization treatment can be easily made.

In one embodiment, the slag excretion work that floats on the upper part of the molten iron in the ladle may be performed by using a skimmer device in the KR (Kanvara Reactor). This is to remove oxidative slag such as silicon dioxide (SiO ₂ ) reacted during refining operation in the pretreatment converter to satisfy the desulfurization operation conditions.

In one embodiment, the impeller (Impeller) can be carried out by adding a desulfurizing agent after starting the molten iron stirring by lowering. After the desulfurization treatment is completed, a temperature probe and probe can be installed in the temperature measurement system.

In one embodiment, after the desulfurization treatment, a slag floating above the molten iron in the ladle is once again by using a skimmer apparatus for the purpose of preventing abdominal sulfur in the decarburization converter, which is the next process. Can be excluded.

In one embodiment, the desulfurization treatment time can be operated at 18-25 minutes / Ht. Under these conditions, sufficient desulfurization treatment time can be ensured.

(S20) De-silicon  step

In this step, the desulfurized molten iron is repaired in a ladle and charged into a pretreatment converter, and the molten iron is blown by blowing oxygen to desilicon (Si) treatment. In the pretreatment converter, in addition to the desilicon (Si), some delineation (P) treatment may be performed.

During the operation of the blast furnace, if the wind flowing into the furnace through the tuyere does not pass through the charges uniformly, it causes drift and reaches the top of the blast furnace. Abnormally produced. In particular, the content of silicon (Si) in the molten iron is increased.

In one embodiment, the molten iron repaired on the ladle is silicon (Si): 0.6-8.0 wt%. When the silicon content is less than 0.6% by weight, the reaction between oxygen and silicon is not easily performed when charged into the pretreatment converter, and it is difficult to deal with silicon, and when it exceeds 8% by weight, the phenomenon of slinging during refining may occur. As a result, the quality of the molten steel produced may be degraded. For example, the drawn molten iron may be 2 to 8 wt% of silicon (Si). For example, the drawn molten iron may be 4 wt% to 8 wt% of silicon (Si).

In one embodiment the temperature of the molten iron repaired to the ladle may be 1,200 ℃ ~ 1500 ℃. Desilicon treatment can be facilitated in the temperature range.

When the decarburization process is performed by applying the molten iron containing silicon according to the present invention, and then the desilicon process is performed, the risk of overflowing the molten iron during the operation increases, causing equipment load and damage, and the safety of the worker. Threat to the environment and adversely affect the environment.

In one embodiment, during the de-silicon (Si) treatment, a sub-raw material including 10 to 45 kg / t-s of quicklime (CaO) (per mol of steel) and 15 to 140 kg / t-s of coolant may be added to the pretreatment converter. When the amount of the secondary raw material is added, the molten iron and the secondary raw material may effectively react, so that the desilicon treatment efficiency may increase. For example, during the desilicon treatment, a subsidiary material containing 15 to 35 kg / t-s of quicklime (molten steel) and a coolant 20 to 130 kg / t-s may be added. In one embodiment, the coolant may include one or more of iron ore, sintered ore, hot briquetted iron (HBI) and briquettes.

In one embodiment, when the molten iron is blown, the oxygen lance height: 2,300 ~ 2,500mm based on the molten steel surface in the pre-treatment furnace, the blow flow rate: 25,000 ~ 30,000Nm3 / h conditions, and when the molten iron is blown, Quantity: It can blow on 10-25 Nm <3> / ts conditions. In the blowing condition, the desilicon treatment can be easily made. As an example, when the delivery flow rate is less than 25,000 Nm 3 / h, the desilicon treatment time may increase more than necessary. On the other hand, when the delivery flow rate exceeds 30,000 Nm 3 / h, there is a risk of molten iron overflowing during operation.

Figure 2 shows a pretreatment converter for the desilicon treatment of the present invention. Referring to FIG. 2, when the molten iron is blown, the height H of the oxygen lance 10 is set to 2,300 to 2,500 mm based on the uppermost surface (hot water surface) of the molten iron M charged in the pretreatment converter 20. Can be. In the above conditions, blowing can be easily performed.

In one embodiment, the molten iron blown, it can be blown under the oxygen blowing amount: 10 ~ 25Nm3 / t-s conditions. De-silicon treatment may be easily performed at the oxygen injection amount.

In one embodiment, the amount of oxygen blown in the pretreatment converter is calculated by the difference between the silicon (Si) content of the charged molten iron, the difference of the target silicon (Si) content in the desilicon treatment, and the ladle It can be derived by calculating the difference in tapping temperature rise after desilicon treatment at the repaired molten iron temperature. When the oxygen is blown, the molten iron temperature rises due to an exothermic reaction caused by an oxidation reaction generated in contact with silicon (Si) or the like in the molten iron.

In one embodiment, the silicon (Si) content of the desiliconized molten iron is reduced by 0.2 to 6% by weight based on the silicon (Si) content of the molten iron charged into the pretreatment converter, The temperature may be 1,450-1,600 ° C. For example, it may be reduced by 0.2 to 1% by weight based on the silicon (Si) content of the molten iron charged into the pretreatment converter.

In one embodiment, the desilicon-treated molten iron is silicon (Si): 0.1 to 3.5% by weight, and the temperature may be 1,450 to 1,600 ° C. Under the above conditions, when the desilicon-treated molten iron is blown in a decarburization converter, it is possible to stably control the phosphorus (P) component in the molten iron and to prevent a slopeing phenomenon, thereby making it easier to decarburize. . For example, the desilicon-treated molten iron is silicon (Si): 0.1 to 1% by weight, and the temperature may be 1,450 to 1,600 ° C. In another example, the desilicon-treated molten iron is silicon (Si): 0.2 to 0.5% by weight, and the temperature may be 1,450 to 1,600 ° C.

(S30) Tapping  step

The step is to tap the desilicon-treated molten iron. Figure 3 shows the tapping of the desilicon treated molten iron according to one embodiment of the present invention. Referring to FIG. 3, the tapping operation is performed by tilting the pretreatment converter 20 to transfer the molten iron M to the tapping ladle 30 through a tap hole 24 formed on an outer circumferential surface of the pretreatment converter 20. You can tap. When the molten iron (M) tapping through the tapping hole 24 as shown in FIG. 3, the slag (S) formed on the upper surface of the molten iron (M) may be excellent. In one embodiment, the slag remaining in the pretreatment converter may be treated by exclusion from the pot.

(S40) Decarburization  step

In the step, the desulfurized molten iron is charged into a decarburization converter and subjected to decarburization (C). The decarburization may be carried out in a conventional manner.

In one embodiment, the decarburized molten iron may include 0.1 wt% to 1.0 wt% of silicon (Si), and may have a temperature of 1,300 to 1,600 ° C. In the treatment under the above conditions, the continuous casting process may be performed after controlling the fine components in the molten steel through a conventional secondary refining process.

When applying the reversed converter process (RCP) according to the present invention, it is possible to manufacture molten steel by refining molten iron of high silicon (Si), which had to be subjected to cold wire, casting ship, or sand treatment, because existing steelmaking was impossible. In the case of molten iron, it prevents the sloping phenomenon to prevent environmental pollution, and it has excellent operation stability, can raise the molten iron temperature stably, and can prevent the load and damage of equipment during refining, and pretreatment The slag removal efficiency in the converter is excellent, and the economic efficiency can be excellent because of the excellent effect of reducing the operating cost.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Examples and Comparative Examples

Example 1

High silicon molten iron was treated in the same manner as in FIG. 4. Silicon (Si): 3.5% by weight, molten iron with a molten iron temperature of 1,393 ° C. was repaired in the ladle, and although not shown, moved to a KR (Kanvara reactor) facility and subjected to desulfurization, followed by FIG. 4A. Charge the desulfurized molten iron into the pretreatment furnace as described above, and add quicklime (CaO): 29 kg / ts and coolant (iron ore): 123 kg / ts as an auxiliary material, and an oxygen content of 17 Nm3 / ts using an oxygen lance. Blown into the molten iron, the molten iron temperature was increased by an exothermic reaction by the oxidation reaction of silicon (Si) and carbon (C) and the like (SiO ₂ and CO generation), and the silicon removal treatment was performed as shown in FIG. 4 (b).

During the de-silicon treatment, the oxygen lance height was set to 2,300 to 2,500 mm based on the molten steel surface (upper surface) charged inside the pretreatment furnace, and blown under a condition of a flow rate of flow: 25,000 to 30,000 Nm 3 / h. After the oxygen was blown and de-siliconized, a probe was mounted on a sub-lance, which is a temperature measuring facility, and the temperature of the molten steel in the pre-treatment furnace was measured. The desilicon-treated molten iron included silicon (Si): 0.5 wt% and the molten iron temperature was 1,539 ° C.

Thereafter, as shown in FIG. 4C, the preprocessing converter was tilted to tap the desilicon-treated molten iron through the tap hole formed on the outer circumferential surface of the preprocessing converter. The slag remaining in the pretreatment converter was removed from the pot and treated. Thereafter, as shown in FIG. 4 (d), the molten molten iron was charged into a decarburization converter, and after decarburization (C) treatment, the steel was dropped into the tapping ladle as shown in FIG.

The process, composition and temperature change in the steel mill are summarized as follows.

The process proceeded to repair, pretreatment and decarburization, and the molten iron was changed from 3.5% by weight to 0.5% by weight of silicon (Si), and from 1,393 ° C to 1,539 ° C.

Example 2

A molten iron containing 3.1 wt% of silicon (Si) and a molten iron temperature of 1,261 ° C. was repaired in the ladle. After going to the KR (Kanvara reactor) facility and desulfurizing, charge the desulfurized molten iron into the pre-treatment converter, add quicklime (CaO): 29 kg / ts and coolant (iron ore): 87 kg / ts as feedstock. , Oxygen lance blows up the net oxygen: 19 Nm3 / ts, and raises the molten iron temperature by exothermic reaction by oxidation reaction (SiO ₂ ) and CO with silicon (Si) and carbon (C) in molten iron Desilicon treatment was carried out.

During the de-silicon treatment, the oxygen lance height was set to 2,300 to 2500 mm based on the molten steel loaded into the pretreatment furnace, and blown under a condition of a flow rate of 25,000 to 30,000 Nm 3 / h. After the oxygen was blown and de-siliconized, a probe was mounted on a sub-lance, which is a temperature measuring facility, and the temperature of the molten steel in the pre-treatment furnace was measured. The desilicon-treated molten iron included silicon (Si): 0.33 wt% and the molten iron temperature was 1,534 ° C.

Thereafter, the preprocessing converter was tilted to tap the desilicon-treated molten iron through the tap hole formed on the outer circumferential surface of the preprocessing converter. The slag remaining in the pretreatment converter was removed from the pot and treated. Thereafter, the molten iron was charged into a decarburization converter and subjected to decarburization (C).

The process, composition and temperature change in the steel mill are summarized as follows.

The process proceeded to repair, pretreatment and decarburization, and the molten iron was changed from 3.1 wt% to 0.33 wt% of silicon (Si) and the molten iron temperature from 1,261 ° C to 1,534 ° C.

Comparative example

High silicon molten iron was treated in the same manner as in FIG. 5. The molten iron containing 3.5 wt% of silicon (Si) and the molten iron temperature of 1,393 ° C was repaired in the ladle, charged into a decarburization converter as shown in FIG. 5 (a), and decarburized as shown in FIG. 5 (b). Then, the decarburization converter was tilted as shown in FIG. 5 (b) to tap through the furnace and remove slag. Subsequently, oxygen was blown into the decarburization converter as shown in FIG. 5 (d) to blow molten iron, treated with desilicon (Si), and pulled out as shown in FIG. 5 (e).

At this time, the complete rejection of the slag was not made, the amount of residual slag in the decarburization converter was large, and due to the high silicon molten iron, the molten iron overflowed into the furnace port of the decarburization converter.

6 is a graph showing a silicon content change of the molten iron according to the molten iron refining process of Examples 1 to 2 according to the present invention. 7 is a graph showing the molten iron temperature change according to the molten iron refining process of Examples 1 to 2 according to the present invention.

Referring to the results of FIGS. 6 and 7, the molten iron of Examples 1 to 2 of the present invention is applied to the molten iron of high silicon (Si), which was previously impossible to be steel-making and had to be subjected to cold wire, foundry or sand treatment. In addition, the normal desilicon and decarburization process is performed, it was possible to refine the molten iron, it was found that the operation stability is excellent, the molten iron temperature can be raised stably, and the load and damage of the equipment during the refining can be prevented. .

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (7)

1. Repairing the molten iron from the blast furnace in the ladle and moving to a KR (Kanvara reactor) facility, and adding a desulfurization agent to desulfurization (S);

   Charging the desulfurized molten iron into a pretreatment converter, blowing oxygen by blowing the molten iron, and then treating the molten iron to remove silicon (Si);

   Tapping the desilicon-treated molten iron; And

   And charging the molten molten iron into the decarburization converter to perform decarburization (C).

   The molten iron repaired on the ladle comprises silicon (Si): 0.6 ~ 8.0% by weight.
2. The method of claim 1,

   In the de-silicon (Si) treatment, molten iron refining method in the converter characterized in that the auxiliary raw material containing 10 ~ 45kg / t-s and quickener 15 ~ 140kg / t-s in the pretreatment converter.
3. The method of claim 1,

   When the molten iron is blown, it is blown under an oxygen lance height of 2,300 to 2,500 mm based on the molten steel surface of the pretreatment converter at a delivery flow rate of 25,000 to 30,000 Nm3 / h.

   The molten iron refinement method in the converter, characterized in that the blown under the molten oxygen blown: 10 ~ 25Nm 3 / t-s conditions.
4. The method of claim 1,

   The silicon (Si) content of the desilicon-treated molten iron is reduced by 0.2 to 6% by weight based on the silicon (Si) content of the molten iron charged into the pretreatment converter.

   The molten iron refining method of the converter characterized in that the temperature of the desilicon-treated molten iron is 1,450 ~ 1,600 ℃.
5. The method of claim 1,

   And said tapping taps said preliminary converter to tap the molten iron through a tap hole formed on an outer circumferential surface of said preliminary converter.
6. The method of claim 1,

   The decarburized molten iron, the silicon (Si): 0.1 to 1.0% by weight, the molten iron refining method in the converter characterized in that the temperature is 1,300 ~ 1,600 ℃.
7. The method of claim 1,

   The molten iron repaired in the ladle is silicon (Si): 4.0 to 8.0% by weight of the molten iron in the converter.

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