KR101091954B1 - Method of manufacturing converter molten steel using dephosphorized molten metal - Google Patents

Abstract

According to the present invention, a method for producing converter molten steel using a delineated molten iron is based on the input of quicklime and hot briquettes according to slag of quantitative 10 to 15 tons suitable for the work of delineated molten iron. The residual slag can be solidified to prevent explosion during charging of the delineated molten iron, and the input amount of _secondary raw materials can be reduced by utilizing CaO, FeO, MnO and SiO ₂ , which are useful components contained in the residual slag during the blowing operation of the delineated molten iron, especially the quality In addition to the effects of improved, stable productivity of molten steel, and cost reduction, there is an advantage of reducing slag treatment cost and preventing environmental pollution by preventing the operation of completely removing residual slag prior to charging the Tallinn molten iron.

Tallinn charter, refining, slag, molten steel, hot briquettes, quicklime

Description

Method for manufacturing converter molten steel using Tallinn molten iron {Method of manufacturing converter molten steel using dephosphorized molten metal}

1A to 1D are work flow charts showing the progress of the converter work, which is a work situation diagram showing charging work, drilling work, tapping work, and exclusion work, respectively.

2 is a cross-sectional view showing the furnace reaction during the blowing operation of the converter.

Figure 3a is a cross-sectional view showing the reaction in the furnace during the blowing operation of the Tallinn molten iron charged after the complete removal of the residual slag by the conventional method.

Figure 3b is a cross-sectional view showing the reaction in the furnace during the blowing operation of the Tallinn molten iron charged after the exclusion operation according to the residual slag quantification according to the present invention.

4 is a work flow chart according to the present invention.

Figure 5a is a graph showing the blowing pattern and the subsidiary raw material injection method of the Tallinn molten iron according to the conventional method.

Figure 5b is a graph showing the blowing pattern and the subsidiary feed method of the Tallinn molten iron according to the present invention.

Figure 6a is a graph showing the change in the content of the phosphorus (P) component according to the blowing time during the blowing operation of the Tallinn molten iron in the conventional method and the present invention.

Figure 6b is a graph showing a change in the content of iron oxide (FeO) component according to the blowing time during the blowing operation of the Tallinn molten iron in the conventional method and the present invention.

Figure 6c is a graph showing the change in basicity according to the blowing time in the conventional method and the present invention.

<Explanation of symbols for the main parts of the drawings>

1: lance 4: slag

5: cavity 6: quicklime

7: flash point 8: low odor gas (N ₂ , Ar)

9: skirt 10: quicklime in the state of the goods

12: now

The present invention relates to a method for producing converter molten steel using a dephosphorization molten iron having a phosphorus (P) content of 0.060 wt% or less, and more specifically, to remove the slag generated during the converter refining operation and to improve the method of adding raw materials to the delineation molten iron. Utilize residual slag by securing suitable quantified residual slag and by adding quicklime and hot briquette iron (HBI) to solidify the residual slag to prevent the explosion that may occur during charging of the leased line. The present invention relates to a method for manufacturing converter molten steel using a Tallinn charter, which is characterized by reducing the amount of auxiliary materials used during converter refining of the Tallinn charter and improving the method of input of the materials.

The steelmaking process proceeds in the order of molten iron pretreatment, converter refining, secondary refining and continuous casting. In order to produce low impurity PI materials and ultra-low-lining high-grade steels, slag generation and slag generation time are shortened, and delineation charter is used to improve productivity. The molten iron prepared by melting iron ore in the blast furnace has a high phosphorus (P) content of 0.080wt% to 0.130wt%. Therefore, in the converter refining process, many auxiliary materials must be used to lower the phosphorus (P) component in the molten steel to 0.025wt% or less. As a result, the amount of slag generated is high, so the slag treatment cost increases, and it is difficult to control the phosphorus (P) component in the production of ultra-low steel with phosphorus (P) content of molten steel of 0.010wt% or less. Blow out the dephosphorization material and oxygen at the phosphorus (P) content in molten iron and dephosphorize to 0.060wt% or less.

Among these delinquency molten irons, molten iron is removed from molten iron by having a high content of impurities and carbon and removing a very high amount of carbon and impurities by injecting molten iron into a converter and injecting pure oxygen.

1A-1D show the progress of this converter operation.

First, the scrap iron and molten iron is charged to the converter (FIG. 1A), and the blowing operation is performed at high temperature by blowing oxygen at high pressure (FIG. 1B). The tapping operation of the converter after finishing the drilling operation is carried out to release the molten steel to the ladle (Fig. 1c), and the remaining slag in the converter is subjected to the exclusion work of treating the converter to the pot by tilting the converter 180 degrees forward. (FIG. 1D).

2 is a cross-sectional view showing the furnace reaction during the blowing operation, when the molten iron is charged into the converter and the pure oxygen 2 is blown in through the lance 1, the oxygen jet collides with the molten iron to form a cavity 5 in the shape of a parabola. And the melting point (7) where molten iron and oxygen are burned is formed.

The blowing operation of the converter can be said to be a process of removing impurity elements in the molten iron by removing the pure oxygen gas 2 through the lance 1 to the slag 4 layer. At this time, the slag (4) is necessary for the stable removal of the impure element, which can be adjusted depending on how to input the sub-materials during the blowing.

The impurity element in the molten iron during the blowing operation of the converter is subjected to the oxidation reaction such as the pure oxygen gas blown into the following reaction formula 1 to 5.

[C] + 1/2 O ₂ = CO _(g)

[Si] + O ₂ = SiO ₂

[Mn] + 1/2 O ₂ = MnO

[Fe] + 1/2 O ₂ = FeO

2 [P] + 5/2 O ₂ = P ₂ O ₅

According to Scheme 1, carbon is oxidized to carbon monoxide (CO) to be removed in the gas phase, and Schemes 2 to 5 are present in the slag layer while the secondary materials introduced during the converter operation are recycled.

Silicon oxide (SiO ₂ ) formed by oxidation of silicon in Scheme 2 reacts with quicklime (the main component is CaO), which is a _secondary material, to form CaO—SiO ₂ . The melting point of pure quicklime is high at 2750 ° C, making it difficult to rehydrate (liquid), but when it is formed of CaO-SiO ₂ , the melting point drops to 1450 ° C. In addition, if iron oxide (FeO) is supplied to iron ore (main component is FeO) or residual slag, CaO-SiO ₂ -FeO is formed, melting point is lowered to 1300 ℃ and quicklime is easily formed into liquid phase and mixed into slag. .

The slag layer thus formed reacts with the molten iron actively by stirring action by the collision energy of low odor gas (N ₂ , Ar) and pure oxygen to stably remove impurities in the molten iron, and particularly to remove and stabilize the phosphorus (P) component. Plays an important role.

As such, slag plays an important role in removing impurities in the molten iron and controlling the phosphorus (P) component of the molten iron, and the components such as CaO, FeO, MnO, and SiO ₂ included in the residual slag form the slag. Can act as a mediator to

However, after recognizing that the use of residual slag generated in the previous charge leads to phosphorus (P) contamination by P ₂ O ₅ among the components of the residual slag, it is conventionally finished after the drilling work and the coating is completed before the charging of the next delinquency chart. The converter was tilted 180 degrees to completely exclude any residual slag left in the converter.

Table 1 below shows the highest and lowest chemical constituents of the residual slag of general and Tallinn molten metals measured during three months of operation.

As can be seen in Table 1, the slag of the general molten iron includes a P ₂ O ₅ of 2.67 to 3.5% and the slag of the Tallinn molten iron comprises a P ₂ O ₅ of 1.44 to 2.66%. As such, slag of Tallinn molten iron has a smaller amount of P ₂ O ₅ than slag of general molten iron, but conventionally, the slag characteristics of the Tallinn molten iron cannot be utilized by completely excluding residual slag. There was no significance in the quantification of residual slag.

When the molten iron is charged into the converter after complete exclusion and is blown without residual slag, the molten iron has 0.05% or less of silica (Si), 0.15% of manganese (Mn), and phosphorus (P) due to the characteristics of molten iron. Since the c) component contains a low content of 0.020 to 0.060%, there is a lack of an oxide to react with oxygen to form a slag layer, so that active reaction composition of molten iron and slag as shown in FIG. 2 is difficult.

In particular, high melting point (2750 ℃) quicklime, which is added to control phosphorus (P) component in molten iron, does not form low melting point CaO-SiO ₂ (1450 ℃) due to lack of silicon oxide (SiO ₂ ) in slag. . The unrefined high viscosity quicklime cannot react with each other as the slag (4) and the molten iron (3) are mixed at the fired point, that is, at the interface between the slag (4) and the molten iron (3) by oxygen supplied through the lance. In addition, spitting occurs when the quicklime 6 protrudes to the outside together with the molten iron 3. Referring to FIG. 3A, the sputtering phenomena (P) to be removed and stabilized in the slag (4) as well as deterioration of the equipment by attaching the iron (12) to the lance (1) and the iron particles around the skirt (9). Removal of components is difficult.

Therefore, conventionally, in order to promote quicklime ash (liquidization), Fe-Si for slag ash was added prior to the start of blowing to generate primary SiO ₂ oxide early. In order to protect the furnace body from the generation of oxide in the early stage of the drilling, light dolomite was added 10% before the blowing, quicklime was divided into the pieces during the drilling, and a large amount of fluorite was added from 15% of the blowing to promote the ashes of the quicklime. After 10% of the blow, the blow-off of the Tallinn charter was carried out by dividing the tank.

However, since slag is completely excluded after slag coating, the basicity of quicklime in coating dolomite and light dolomite is insufficient, and MgO contained in the coating material prevents the elution of MgO from the furnace furnace. Usage increases Such a large amount of quicklime and light dolomite has a problem of causing slag fluidity deterioration.

In addition, due to the large amount of Fe-Si and fluorspar injected into the slag goods, the T.Fe content of the end slag increases, resulting in shortening of the life of the furnace due to the peroxidation of the slag and an increase in the manufacturing cost of the molten steel.

It is difficult to control the stable molten steel component due to many problems and unsafe operations as described above, and in particular, due to the complete exclusion of slag, the treatment cost increases and causes environmental pollution.

Furthermore, if the demolition molten iron is loaded into the converter with residual slag as it is, the residual slag component (O) and the carbon component (C) of the molten iron react with each other to generate carbon monoxide (CO) gas. There is a risk of this happening.

The present invention has been made to solve the problems of the prior art described above, in the production method of converter molten steel using a delineated molten iron which is advantageous for productivity improvement by reducing the slag generation amount and shortening the time for the production of high-strength steel PI material low slag production The protective slag and hot briquettes are added to the converter leaving residual slag quantitatively suitable for the Tallinn molten iron, and the remaining slag is solidified by preventing the explosion during the charging of the Tallinn molten iron by adding protected quicklime and hot briquettes. It aims to drastically reduce the input amount of auxiliary materials and to promote continuous slag goods to prevent deterioration of facilities by unrefined high viscosity slag and to enable stable phosphorus control.

In order to achieve the above object, a method for producing converter molten steel using the delineation molten iron according to the present invention comprises: excluding the part of the remaining slag in the converter after the tapping, leaving the quantified residual slag suitable for the delineation molten iron in the converter, the quantification Putting the protective quicklime and hot briquettes into the remaining residual slag and solidifying the residual slag by tilting the furnace body, checking the solidification of the remaining slag, charging the delineated molten iron, and adding subsidiary materials and carrying out a drilling operation. .

Residual slag remaining in the converter, step of quantifying by initially removing a predetermined amount of the remaining slag in the converter finished tapping, applying a coating material to the nitrogen spray coating and a predetermined amount of the remaining slag in the converter finished coating Quantifying by excluding second.

The step of initially excluding and quantifying the predetermined amount of the residual slag, it is determined whether the occupancy of the Tallinn molten iron is initially occupied, and if the initial occupancy of the Tallinn molten iron is initially excluded 2/3 of the furnace slag generated during the drilling work of general molten iron In the case of continuous charge of the Tallinn molten iron, it is characterized in that an initial rejection of 1/3 of the furnace slag generated during the blowing operation of the Tallinn molten iron is performed. Subsequently, the step of coating by coating the coating material, the coating material 5 to 6kg / T-S if the initial charge of the delineation molten iron, and the coating material 3 to 5kg / T-S if the continuous charge of the delineation molten iron. In addition, the step of quantifying by removing the predetermined amount of the residual slag secondly, if the initial charge of the Tallinn molten iron is excluded so that the final slag is 35 to 50kg / TS, if the continuous charge of the Tallinn molten iron is the final slag 30 to 45kg / TS It is characterized by the exclusion to be.

The protective quicklime is added to 5 to 8kg / T-S, hot briquettes are characterized in that to put 5 to 15kg / T-S.

In addition, in the step of carrying out the drilling work with the input of the sub-material, Fe-Si is added 0.8kg / TS within 3% after the start of the converter, and split into 30% and 45% of the additional injection, iron ore 3% 5 to 10kg / TS at the time of injection, and additional heat is added at 40% and 55% of the time of free heat generation, quicklime is separately input at the time of 30% and 50% of the blow, fluorspar is put at the time of 35% of the blow, The light dolomite is characterized in that the injection at 50% of the time.

Hereinafter, with reference to the accompanying drawings will be described in detail the manufacturing method of the converter molten steel using the delineation molten iron according to the present invention.

As shown in Figs. 1A to 1D, the converter work process proceeds in the order of charging work (FIG. 1A), blowing work (FIG. 1B), tapping work (FIG. 1C) and exclusion work (FIG. 1D), and FIG. The process progress of the converter molten steel manufacturing method using the delineation molten iron by

After finishing the tapping work, the remaining slag is quantified to prevent phosphorus (P) contamination by P ₂ O ₅ among the components of the slag generated in the previous charge so as to be suitable for the work of the next charge Tallinn molten iron. Since the slag of the general molten iron and the slag of the Tallinn molten iron are different, in the method for producing converter molten steel using the Tallinn molten iron, the component of the molten iron is checked to confirm whether the molten iron is initially occupied (S1 to S2).

First, in the case of utilizing slag generated after the blow job of the general chartered ship in the Tallinn charter work, the residual slag quantification method of the initial charge of the Tallinn charterer is applied (S3 to S5). That is, when the tapping is completed, the initial removal of slag generated during the drilling of the general charterer is performed, and the slag in the furnace is largely excluded by referring to 50 to 60% of the slag removed from the slag pot (S3). ). At this time, the slag generated during the drilling of the general charter is 109 to 145kg / TS (about 30 to 40 tons per charge) and in the present invention using the Tallinn charter in the work using a general charter to remove slag by tilting the converter 103 degrees The tilt angle of the converter at 103 to 108 degrees is further tilted to allow more slag to be excluded. After the initial rejection of the residual slag, the converter is established and nitrogen spray coating is performed by adding 5 to 6 kg / T-S of dolomite and light dolomite as coating materials (S4). Then, the reactor is repeatedly tilted 2 to 3 times so that the final slag amount remaining in the converter is quantified to 35 to 50 kg / TS (about 10 to 15 tons per charge), which will be described later through the embodiment of the present invention. S5).                     

As such, the residual slag of the general molten iron is quantified to about 35 to 50 kg / T-S, and then the residual slag of the Tallinn molten iron is quantified as described below (S6 to S8). That is, when the tapping is completed after the blow job using the Tallinn charter, tilt the converter to 103 to 108 degrees to exclude the slag generated during the drilling of the Tallinn charter (S6). At this time, the slag of the Tallinn molten iron is 55 to 90 kg / T-S (about 18 to 25 ton per charge), and the slag in the furnace is excluded by a third by referring to 10 to 20% of the slag excluded from the slag pot. However, when slag generation increases due to over-injection, about 2/3 of the slag in the furnace is initially excluded, and the following operations are the same. After the initial removal of the slag in the same manner as above, the converter is established and nitrogen spray coating is performed by putting 3 to 5 kg / T-S of dolomite and light dolomite as coating materials (S7). Thus, the final residual slag amount remaining in the converter is maintained at 30 to 45 kg / T-S (10 to 13 tons), which is reduced than that of the initial charge of the Tallinn molten iron (S8).

The total slag produced and maintained during the blowing operation of the Tallinn chartered ship is 55 to 90 kg / T-S, which is half the slag of 109 to 145 kg / T-S produced during the drilling operation of the general charter boat. As the amount of slag generated in the furnace is reduced in the continuous operation of the molten iron, the amount of coating material is reduced and the MgO component of the slag is maintained at 8 to 10% to prevent the slag fluidity from deteriorating.

If the slag amount generated in the blow job of the general charter, which is the last charge in the initial charging operation of the Tallinn charter, is large, the phosphorus (P) content is easily eliminated because the phosphorus (P) content is easily reduced by the Tallinn operation in the pretreatment process. Due to the specificity of the molten iron, the quicklime input should be increased. The P ₂ O ₅ component contained in the slag of the normal quick-flow slag added to the slag can be reduced from 2.80 to 3.50% to 2.30 to 2.60% or less to prevent the occurrence of clogging due to residual slag. In addition, it is important to quantify the remaining slag of the Tallinn Charter to promote slag goods.

Here, the criterion for quantifying the residual slag (10 to 15 tons) of the Tallinn molten iron described above is when the slag is initially removed and the coating operation is performed after the coating material is added, and the mixing of the slag and the coating material is in good condition. When the secondary slag is excluded, the converter tilt angle is 110 to 125 degrees to induce quantification of residual slag.

When dephosphorization molten iron is charged into the converter while the remaining slag of the quantitative amount is left in the converter, the oxygen component (O) and the carbon component (C) of the molten iron react with each other to generate carbon monoxide (CO) as shown in Scheme 6 below. By doing so, an explosion phenomenon due to gas generation may occur.

[O] _slag + [C] _iron = CO (g)

In order to prevent the explosion, the present invention puts 5 to 8 kg / TS of quicklime used as an auxiliary material and 5 to 15 kg / TS of hot briquettes having iron content of about 80% or more before charging the molten iron in order to prevent the explosion (S9). . When the converter is repeatedly tilted 1 to 3 times, the oxygen component (O) in the remaining slag is absorbed by the unbaked quicklime to prevent generation of carbon monoxide upon charging of the delineation molten iron. In addition, hot briquette iron (HBI) can cool the slag and prevent the carbon monoxide gas generated by the carbon component (C) in the molten iron to prevent the explosion phenomenon during the charging of the delineated molten iron.

As such, the residual slag is quantified and the slag is solidified by the injection of quicklime and hot briquettes to prevent the explosion, and then the delineation molten iron is charged into the converter (S10 to S11). Then, the high-pressure oxygen gas is blown to remove impurities, and various kinds of subsidiary materials are added to perform the blowing operation (S12). When oxygen (2) is blown in through the lance (1), the residual slag which has already been re-dissolved by the oxidation reaction during the blowing operation of the previous charge in the reaction between the molten iron (3) and the slag (4) is dissolved early, and the CaO contained in the residual slag, The components of FeO, MnO, SiO ₂ and MgO react with the protected quicklime added before charging the delineation molten iron. As shown in FIG. 3B, as the CaO—SiO ₂ —FeO is formed and mixed with the oxygen jet supplied through the lance 1, and the quicklime melting point drops to 1300 ° C., the quicklime 10 is liquefied at an early stage, thereby causing the flash point (7). The slag 4 and the molten iron 3 take place at the interface (i.e., at the interface between the slag 4 and the molten iron 3). Thus, due to the promotion of the goods of the slag 4, there is no spitting and adhesion of the now 12 of the lance 1 and phosphorus P in the molten iron is controlled and stabilized in the slag as shown in Scheme 7 below.

2 [P] + 5 [FeO] + 4 [CaO] → 4 CaO · P ₂ O ₅ + 5Fe

As described above, the present invention enables the quicklime goods by the residual slag to change the blowing pattern, the subsidiary material input method, and the input amount as shown in FIG. 5B.                     

The blowing pattern is blown with oxygen more strongly than before, while Fe-Si is added at 0.8 kg / TS or less at 0 to 3% of the start of the blow, and additional charge is added at 30% and 45% at the blow time to 30% during the blow period. To promote slag goods promotion of from 70%. In addition, the iron ore injected into the coolant during the blowing is added to the initial 3% of the blowing to supply the iron oxide (FeO) as shown in Scheme 4 to further promote the early quick lime ashing.

Quicklime is divided into 30% and 50% at the time of drilling, fluorite is injected at 35% at the time of drilling, and iron ore is divided into 40% and 55% at the time of drilling, and added to quicklime and 55% at the time of drilling. Promote the small and small dolomite goods.

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

[Example]

In the molten iron pretreatment process, 285 to 290 tons of Tallinn molten iron having a phosphorus (P) content of 0.060% or less is charged to the converter by delineation, and the ultralow carbon steel hardening treatment is performed at 1670 ° C or higher.

First, Comparative Examples 1 to 8 set the blowing pattern by increasing the lance height and weakening the flow rate from the beginning of the drilling by the conventional method, and adding the auxiliary raw materials as shown in FIG. The refining was carried out before 10 consecutive charges of the Tallinn molten iron.

Table 2 below was applied to Comparative Examples 1 to 8 as a reference for the amount of secondary raw material input when the Tallinn molten iron on the basis of 285 tons using the conventional method.

Table 3 below shows the components of the Tallinn molten iron of Comparative Examples 1 to 8 and the amount of the used auxiliary raw materials and the components of the endpoint slag.

In addition, Example 1 applies the residual slag quantification method during the initial charging operation of the Tallinn molten iron in accordance with the present invention prior to the blowing of the Tallinn molten iron. Total initial slag amount of 30 to 40 tons during the drilling work of the general chartered ship is about 2/3 of the slag in the furnace with reference to 50 to 60% of the slag port excavation at 103 to 108 degree of tilt angle. Conduct. In addition, 1530 kg of dolomite or 1280 kg of light dolomite, which is a coating material, is subjected to nitrogen spray coating, and the residual amount is quantified so that the final slag amount remaining in the converter becomes 35 to 50 kg / T-S (10 to 15 tons). Subsequently, 1328 kg of protective quicklime and 1863 kg of hot briquettes were added in the remaining slag state before the start of the blowing, and the converter was repeatedly tilted twice to solidify the slag and confirm the complete solidification state of the remaining slag, and then charged with delineation. Then, the blowing operation is performed while blowing oxygen through the lance by the blowing pattern shown in FIG.

In order to improve the slag goods at the beginning of smelting, 226 kg of Fe-Si was added to 0% of the start of the smelting, 2057 kg of ore (bridging) was added to the 3% of the blasting, and 153 kg of fluorspar was added to the sintering time of 30%. 710 kg of quicklime to help In addition, 773 kg of quicklime and 573 kg of light calcined dolomite, which are added at the time of drilling, are promoted as the goods are promoted by 935 kg of ore (briquette) at 55% of the time of drilling.

In addition, Example 2 blows the delineated molten iron continuously once after the initial charge operation of the delineated molten iron as described above, and applies the residual slag quantification method in the continuous charged operation according to the present invention. That is, after leaving the Tallinn charter, the initial exclusion of about one third of the slag in the furnace is performed by referring to the exclusion amount 10% to 20% in the slag port at the angle of tilting the furnace body 103 to 108 degrees. And 986kg or 1156kg light dolomite as a coating material is added and the residual amount is quantified so that the final slag amount remaining in the converter is about 30 to 45kg / T-S after performing nitrogen spray coating. Subsequently, 1563 kg of protective quicklime and 2560 kg of hot briquettes (HBI) were added in the remaining slag state before the start of the blowing, and the slag was solidified by repeatedly tilting the converter. Then, the blowing operation is performed while blowing oxygen through the lance by the blowing pattern shown in FIG.

In order to improve slag goods at the beginning of smelting, 185 kg of Fe-Si was added to 0% of the start of the smelting, 1462 kg of ore (bridging) was added to 3% at the time of blowing, and 224 kg of fluorspar was added to 35% at the time of blowing. Helps with 1022 kg of quicklime goods. In addition, 996 kg of quicklime and 480 kg of light calcined dolomite, which were added at 50% at the time of drilling, were charged with 780 kg of ore (briquette) at 55% at the time of drilling, while promoting the conversion of goods.                     

Example 3 performs the blowing operation in the same manner as described above, but blows the Tallinn molten iron twice in a row after the initial charging operation of the Tallinn molten iron. The method of quantifying residual slag in continuous charge operation according to the present invention is applied.

Table 4 below shows the chemical composition of the slag molten iron in each Example, the amount of used subsidiary materials and the endpoint slag.

Comparing Comparative Examples and Examples in Table 3 or Table 4, the amount of quicklime, fluorspar, and Fe-Si consumed as a subsidiary material is greatly reduced when the residual slag is quantified and the molten iron is blown, rather than when the residual slag is completely excluded. It can be seen that.                     

Comparative Examples 1 to 8 completely exclude the residual slag after slag coating, so the basicity of quicklime contained in dolomite and light dolomite, which is a coating material, is insufficient, and there is no effect of preventing MgO elution due to MgO contained in the coating material. The average consumption of quicklime is increased to 17.8kg / TS or the average consumption of light dolomite to 6.9kg / TS. Such overload of quicklime and light dolomite reduces slag fluidity.

In addition, 1.9kg / TS of Fe-Si (522kg per charge) and 1.8kg / TS of Fluoride (495kg of charge) are added to the slag to increase the T.Fe from 20 to 35%. Due to the peroxidation of slag, the life of the furnace can be shortened and the manufacturing cost of molten steel is increased.

On the other hand, in Example 1, as a result of performing the initial charging operation of the Tallinn charter, total raw lime consumption was 2811 kg, fluorite was 153 kg, and Fe-Si was 226 kg, which greatly reduced the raw materials and lowered the P ₂ O ₅ component of the slag to 2.613%. Phosphorus component (P) at 0.013 wt% shows stable results. In addition, although 573kg of light and small dolomite was injected during the drilling, the MgO component was 10.1% and the T.Fe component was 17.3%.

Here, the purpose of quantifying the residual slag amount in the initial charging operation of the Tallinn molten iron to 35 to 50 kg / T-S (10 to 15 tons) as follows.

Referring to the slag chemical composition of Table 4, the pure slag amount produced by the oxidation reaction during the blowing in the main component of the molten iron, which is the initial occupancy of the Tallinn molten iron of Example 1, can be obtained as follows. When the total amount is oxidized, 175 kg of SiO ₂ is generated. Referring to Scheme 3, when 40% of Mn is oxidized, 127 kg of MnO is generated. Referring to Scheme 5, 70% of the phosphorus (P) component in molten iron is removed. It can be seen that 187 kg of P ₂ O ₅ is generated. If the total slag generation amount is 23 tons, and if 18.3% of the slag is contained, the amount of T.Fe in the slag is 4209kg. In addition, when the CaO concentration in the slag is 46.3%, the amount of slag generated for 0.80% of quicklime lime 2811kg, 0.56% of 573kg light and small dolomite injected during the blowing and 1221.7kg of CaO converted from the coating material is 8188kg. Therefore, the total slag generated during the tug-in of the Tallinn Charter is 12886 kg.

Therefore, after leaving the slag amount of 35 to 50 kg / TS (10 to 15 tons) of the coating completed in the converter and charging the delineation molten iron, the slag 30 to 45 kg / TS (10 to 13 tons) produced by the oxidation reaction during the above-described blowing operation And 1: 1 ratio to promote the reaction, and quicklime to remove the phosphorus (P) component in the molten iron and dilute P ₂ O ₅ in slag to prevent the _double- tap during tapping.

Therefore, the initial charging method of the Tallinn molten iron of Example 1 presented above is a useful component for the goods CaO, FeO, MnO, SiO ₂ and while minimizing the residual slag amount of the general molten iron to 35 to 50 kg / TS (10 to 15 tons) MgO can be used. Dolomite 1530kg or gyeongso Dolomite 1280kg the coating amount also by increasing the volume of slag in the burnt lime component contained in the continuous charge to the coating material than the increased 1.8kg / TS per charge during operation of the Tallinn molten iron contained in the residual slag in the molten iron general P ₂ O ₅ The concentration of 2.80 to 3.50% is diluted to 2.0 to 2.6% of P ₂ O ₅ contained in the remaining slag of the Tallinn charter, which prevents phosphorus (P) contamination by the residual slag of the general charter during the blowing operation of the Tallinn charter. Basicity (CaOwt% / SiO ₂ wt%) was corrected with the CaO component.

In addition, in Example 2, as a result of two consecutive charge operations of the Tallinn molten iron, 3581 kg of quicklime, 224 kg of fluorite, and 185 kg of Fe-Si were used, and the P ₂ O ₅ component was 2.567%, and the phosphorus component (P) at the end point was 0.013. It shows a stable result of wt%. In addition, even though 480kg of light and small dolomite was injected during the drilling, the MgO component in slag was 9.11% and T-Fe was 17.94%, which has the advantage of preventing overdrinking, old smoke and erosion.

As can be seen from the results of Example 3, as the Tallinn molten iron work progressed, the concentration of P ₂ O ₅ in the slag component dropped to 2.37% and the phosphorus component (P) in the molten steel was further stabilized to 0.011% after three consecutive charges. .

6A to 6C show the behavior of the phosphorus component (P) and the slag component during the blowing operation of the Tallinn molten iron of the comparative example and the example. Figure 6a shows the transition of the phosphorus (P) component of the comparative example and the embodiment in the case of the embodiment to secure the residual slag to form a low melting point slag of CaO-SiO ₂ -FeO system to facilitate the initial goods and compared with the comparative example A more stabilized phosphorus component can be obtained. Looking at Figure 6b it can be seen that the Example secures a large amount of FeO by the residual slag compared to the comparative example to increase the FeO in the slag and form a low melting point slag of CaO-SiO ₂ -FeO-based. In addition, as shown in FIG. 6C, the basicity is increased by the promotion of the initial quicklime ash, and the basicity may be further increased than the comparative example.

As such, the components contained in the residual slag of the Tallinn molten iron liquefy the coating material and the protective quicklime early, and the initial slag material can be regenerated by increasing the basicity and FeO at the initial 10 to 30% of the molten iron. Due to the nature of Tallinn chartered slag, after the middle of drilling, there is no input or a small amount of subsidiary materials, so the reclaimed slag is maintained at the beginning of the drilling to prevent the deterioration of the equipment with the unrefined slag. It is possible to secure stable quality and to reduce the use of all subsidiary materials.

In the manufacturing method of converter molten steel using a delineation molten iron using the residual slag quantified as described above, the present invention aims to form a slag on the basis of the composition of the endpoint slag as shown in Table 5 below.

With reference to the composition of the end point slag of Table 5, the method for preparing converter molten steel using the Tallinn molten iron of the present invention calculates the subsidiary material input reference table as follows.

Table 6 is an auxiliary material input applied when the residual slag quantified to 10 to 15 tons at a temperature of less than 1670 ℃ in the present invention and charged with 285 tons of delineated molten iron. However, in the case of the first charge of Tallinn charterers, the coating material input should be increased by 1.8kg / TS per charge.

Table 7 is an auxiliary material input applied when the residual slag quantified to 10 to 15 tons at a temperature of 1670 ℃ or more in the present invention and charged with 285 tonnes of delineated molten iron. However, in the case of the initial charge of Tallinn charterers, the coating material input should be increased by 1.8kg / T-S per charge.

As described above, as a result of continuously applying for 3 months by the method of the present invention, it was possible to obtain the secondary raw material use results as shown in Table 8.

In Table 8, the quicklime raw unit was reduced from 12.5 kg / T-S to 17.8 kg / T-S and Fe-Si was reduced from 1.1 kg / T-S to 1.9 kg / T-S. In addition, it can be seen that the light dolomite is significantly improved from 6.9kg / T-S to 1.9kg / T-S, and fluorite is 0.71kg / T-S from 1.8kg / T-S.

In this way, the use of residual slag can significantly reduce the amount of all the sub-materials used in the drilling operation of the Tallinn charter, and can reduce the slag treatment cost and prevent environmental pollution due to the conventional total exclusion.

According to the present invention, a method for producing converter molten steel using delineated molten iron is based on the input of quicklime and hot briquettes by adjusting slag generated during the blowing operation of general and delineated molten iron into a quantitative slag of 10 to 15 tons suitable for the work of the delineated molten iron. The remaining slag is solidified to prevent explosion during charging of the delineated molten iron, and the useful components CaO, FeO, MnO, and SiO ₂ contained in the remaining slag during the blowing operation of the delineated molten iron are used to promote the recycling of quicklime. The amount of Si and fluorite used can be greatly reduced. In addition, the quicklime component contained in the coating material increases the basicity necessary to control the phosphorus component (P) of the molten iron, thereby reducing the quicklime effect, and the coating material of slag maintains the MgO concentration in the chemical composition of the slag by more than 8%. Prevent erosion

In particular, the manufacturing method of converter molten steel using the Tallinn molten iron according to the present invention, in addition to the quality improvement, stable productivity of molten steel and cost reduction effect, all the amount of residual slag by tilting the converter 180 degrees in the state where the slag coating is completed prior to charging the Tallinn molten iron. By preventing the work to be excluded in the port, there is an advantage of reducing the slag treatment cost and preventing environmental pollution.

Claims (7)

As a manufacturing method of converter molten steel using a Tallinn molten iron, Leaving a portion of the residual slag in the converter that has finished tapping to leave the quantified residual slag suitable for the Tallinn molten iron in the converter; Inserting protective quicklime and hot briquettes into the quantified residual slag and tilting the furnace body to solidify the residual slag; Confirming the solidification of the residual slag and charging the delineation molten iron; And Incorporating the subsidiary materials and carrying out the drilling work; Remaining the residual slag in the converter, Initially excluding and quantifying a predetermined amount of residual slag in the converter after tapping; Putting a coating material to perform nitrogen spray coating; And Quantifying by preliminarily excluding a predetermined amount of residual slag in the converter after the coating, The step of quantifying by removing the predetermined amount of the residual slag second, Judging whether the occupancy rate of the Tallinn charter boat is the initial charge, the final slag is excluded to be 35 to 50 kg / TS if the initial occupancy of the Tallinn charter, and the final slag is excluded to be 30 to 45 kg / TS if it is the continuous charge of the Tallinn charter boat. The manufacturing method of converter molten steel using the Tallinn molten iron characterized by the above-mentioned. delete The method of claim 1, The step of initially excluding the predetermined amount of the residual slag to quantify, Judging whether the occupancy rate of the Tallinn chartered ship is the first charge, if the initial occupancy of Tallinn chartered ship is initially excluded 2/3 of the furnace slag generated during the drilling work of the general chartered boat. A method for producing converter molten steel using a Tallinn molten iron, characterized in that initial removal of one third of the slag. The method according to claim 1 or 3, The coating by adding the coating material, Determine whether the occupancy of the Tallinn charter is the first charge, and if the initial occupancy of the Tallinn charter, 5 to 6 kg / TS is added to the coating material, if the continuous charge of the Tallinn chartered Tallinn characterized in that the input of the coating material 3 to 5 kg / TS Method for manufacturing converter molten steel using molten iron. delete The method of claim 1, Protective quicklime inject 5 to 8kg / T-S and hot briquettes 5 to 15kg / T-S injecting molten iron using a method of manufacturing molten iron. The method of claim 1, In the step of carrying out the drilling work with the input of subsidiary materials, Fe-Si should be added 0.8kg / TS within 3% after the start of converter blasting, and additionally added at 30% and 45% of blasting, and iron ore 5 to 10kg / TS at 3% of blasting 40% and 55% of the time points are added separately, quicklime is added at 30% and 50% of the time of blowing, fluorspar is added at the time of 35%, and small dolomite is added at the time of 50%. Method for producing converter molten steel using a Tallinn molten iron.

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