KR100384635B1 - High-speed melting method in electric furnace - Google Patents

Abstract

The present invention relates to the operation of the electric furnace, the melting method first determines the amount of the charge to be charged, the apparent specific gravity defined by (weight of the charge) / (over-factor × volume of the electric furnace) is 0.6 ton / ㎥ or less After charging 10-20% of the total amount of solid iron source, charge a certain size mold line in the range of 50-100% with respect to the amount of solid scrap, and then sequentially charge the solid scrap and the mold line in the same manner. Then, it comprises a dissolving, this dissolution method of the present invention can dissolve the charge at high speed by reducing the charging time and heat loss in one charge.

Description

High-speed melting method in electric furnace

The present invention relates to an electric furnace operation, and more particularly to a method that can be melted at high speed by changing the charging pattern of the solid iron source in the electric furnace operation to reduce the charging time and heat loss.

Conventional electric arc furnaces, as shown in FIG. 1, have one or three upper electrodes (3) that are electrical conductors in the middle of a roof (2) located above the furnace body (1) of the furnace. ) Is provided, and the side surface is provided with a tap hole 5 for discharging the molten steel 4.

In most electric furnaces having the above-described structure, charging, dissolving, refining, tapping, and preparation are performed at each stage, and usually, molten steel is manufactured through two charging operations and two melting operations. 2 shows an example of such a general electric furnace operation pattern. In general, after a charge is completed in the operation of the electric furnace as shown in FIG. 2, the time required for completing the next charge is about 55 minutes.

In order to increase productivity in electric furnace operation, the time required for each step should be shortened, but the actual dissolution and refining time is the time to melt and heat up the charges, which is determined by the capacity of the energy supply device. Follows. However, the charging operation of each operation stage of the electric furnace is the time to open the roof (2) of the electric furnace, the charge of the charge in the furnace, so there is a possibility that the overall melting time can be significantly reduced by improving the charging pattern. That is, since the electric furnace handles the melt of high temperature 1500 ℃ or more, as shown in Figure 1, the cooling device 6 is installed outside to protect the equipment, the larger the furnace body 1, the heat loss by the cooling device increases. . On the other hand, if the furnace 1 of the electric furnace is small, the heat loss is small, but the amount of charging is small and the number of charging is increased. Therefore, the contents of the furnace body are generally designed to be 1.0 to 1.5 times the nominal capacity of the electric furnace. . Therefore, in the electric furnace operation performed twice as shown in FIG. 2, the electric furnace operation is improved by shortening the charging time per operation or reducing the number of charges.

For example, Korean Patent Application No. 98-49079 proposes an electric furnace operation technology for shortening the charging time per one time. That is, in the above-described furnace operation method, after the first melting of the charges and again before the second charging, 65-75% of the melt is first applied, and then electric power is applied to heat the residual water remaining in the furnace of the furnace. It is a method of secondary charging and melting. However, this method is mainly an operation method for stabilizing the hearth of an electric furnace, which is not very effective in shortening the operation time of an electric furnace, and basically has two disadvantages of requiring two charging operations and two melting operations. That is, two charging and two melting operations in the operation of the electric furnace has a problem that the heat in the furnace during the charging operation to escape to the outside causing heat loss, thus increasing energy consumption and lengthening the melting time.

The present invention has been proposed to improve the conventional electric furnace operation method, the object of the present invention is to improve the charging method during the operation of the electric furnace to shorten the electric furnace dissolution time in one charge to improve productivity.

1 is a structural diagram of a general electric furnace

Figure 2 is a conventional furnace operation process diagram

3 is a schematic diagram of a charge charged in a conventional electric furnace.

Figure 4 is a schematic view of the charge charged in the electric furnace of the present invention

5 is a graph showing the correlation between the apparent specific gravity of the solid iron source and the electric power unit in electric furnace operation

6 is a charge distribution chart of an electric furnace applied to this embodiment.

Explanation of symbols on the main parts of the drawings

1 ... furnace body 2 ... furnace roof

3 ... electrode 4 ... molten steel

5 ... outlet 6 ... chiller

7 ... scrap scrap 8 ...

In the present invention for achieving the above object in the electric furnace operating method through the charging, dissolving, refining and tapping of the solid iron source,

First, determine the amount of the charge to be charged, the specific gravity of the charge to the following equation 1,

[Equation 1]

Apparent specific gravity = [charge weight of ton (load)] / [excess factor x volume of electric furnace (㎥)]

(However, the excess factor is the volume ratio of the part where the solid content of solid iron source can be filled)

The present invention relates to an electric furnace high-speed melting method characterized in that it comprises a scrap metal, and then the melting of scrap metal so as to be above the apparent apparent weight.

Hereinafter, the present invention will be described in detail.

In the case of loading the charges into the furnace body of the electric furnace, the distribution of the charges loaded into the furnace body is solid scrap 7 and the pig iron 8 as shown in Fig. 3 while leaving a very large void in the furnace body. It is charged. Therefore, the amount of target charges cannot be charged all at once, but must be charged twice through primary dissolution.

The present invention, unlike the conventional charging method, by reducing the number of times of the charge of the charge to the furnace body of the furnace by one time to eliminate the low power input time to the boring of the initial melting, thus reducing the heat loss amount to reduce the energy consumption once It is characterized by further shortening the dissolution time with electricity by charging time.

To this end, the present invention first determines the amount of charges to be charged, and when such amounts are charged, the scrap metal and the liner are charged so that the distribution of the charges is equal to or more than the apparent specific gravity defined by Equation 1, and aims at only one time. The amount to do is to charge. At this time, when the specific gravity of the charged matter is less than the apparent specific gravity defined as in Equation 1, the phenomenon of overflowing the iron source occurs when loading the iron source.

Apparent specific gravity = [loading weight of ton (ton)] / [excess factor x volume of electric furnace (㎥)]

In Equation 1, the excess factor is the volume ratio of the portion of the furnace contents that is capable of filling the actual solid iron source, and in the present invention, it is preferably limited to the range of about 0.8 to 0.9. If the excess factor is less than 0.8, the size of the electric furnace is too large, leading to an increase in the manufacturing cost of the electric furnace, and if it exceeds 0.9, a problem that the charge overflows to the outside occurs.

Specifically, in the case where the target charge amount in the electric furnace having a constant furnace volume is changed, the apparent specific gravity of each charge according to the present invention should be different as shown in Table 1.

Furnace inside volume (m ³ ) / charge weight (ton) Apparent specific gravity of the charge 1.0 > 1.13 tons / m ³ 1.1 > 1.03 tons / m ³ 1.2 > 0.95 tons / m ³ 1.3 > 0.87 tons / m ³ 1.4 > 0.81 tons / m ³ 1.5 > 0.76 tons / m ³

For example, when charging about 67 tons into an electric furnace with a furnace volume of 100 m3 (furnace volume / nominal capacity = 1.5), the charging content is at least 0.76 tons / Solid scraps and dies should be charged to be above m3. If you keep the apparent specific gravity of the charge as shown in Table 1, you can work with one charge depending on the shape of the old body. Figure 4 shows the distribution of such a charge of the present invention.

As a specific method for charging scrap scrap and molds so as to have an apparent specific gravity of the contents as shown in Table 1, preferably, solid scraps with large voids are first charged with 10-20% of the total charge amount, and then the molds are recalled. The amount of the solid scrap is charged in the range of 50 to 100%, and the solid scrap and the mold line are sequentially loaded in the same manner.

At this time, in the present invention, the iron source having a large pore refers to scrap iron having an apparent specific gravity of 0.6 ton / m 3 or less, and the solid scrap may include pipes, structure dismantle scrap, and the like. When using the iron source with an apparent specific gravity exceeding 0.6 ton / m ³ as a large iron source, the iron source subsequently charged does not enter the gap. Accordingly, it is preferable to use scrap iron having an apparent specific gravity of 0.6 ton / m ³ or less as an iron source having large voids.

In the present invention, the mold is an iron source having a carbon concentration of 1% or more, and is a solid iron source manufactured in a constant mold. Such molds are usually thick due to the characteristics of the mold, so that they do not melt well. When the carbon concentration is 1% or more, the melting point of the iron source is lowered, so that the mold can be easily dissolved. The size of the mold according to the present invention is preferably 200 × 200 × 500 mm or less, more preferably using a carbon concentration of about 3.5 to 4.5% and a size of about 150 mm × 100 mm × 300 mm. If the mold line is larger than 200 × 200 × 500mm, the effect of filling voids becomes small, and the volume of the entire iron source becomes large, and when it is charged into an electric furnace, it overflows.

When charging solid scraps and dies into an electric furnace, the charging operation usually uses a charging basket. In other words, the solid iron source is loaded into the charging basket, and then the charging basket is transferred to the crane and charged in an electric furnace. Therefore, when a solid iron source is loaded into a charging basket, 10% to 20% of the total amount of charged iron sources such as waste scrap metal and structural dismantle scrap metal are loaded into the bottom of the charging basket, and then manufactured into a mold of a constant size. If Cheolwon is loaded with 50% to 100% of the amount of scrap scrap scraped, and then the iron source made of large voids and the mold is alternately loaded, the furnace body of the electric furnace has a similar charging distribution. If the loading amount of the iron source with a large gap is less than 10%, the basket equipment is damaged, and if the amount exceeds 20%, the iron sources are entangled with each other. In addition, when the loading amount of the die is less than 50% or more than 100% it is impossible to charge the scrap scrap so as to be more than the apparent specific gravity.

On the other hand, the relationship between the characteristics of the solid iron source and the power consumption in the ordinary electric furnace operation, which is usually charged twice, melting twice, as shown in Figure 5, there is a problem that the power consumption increases when the apparent specific gravity of the charge is increased. In other words, when the furnace content and the nominal capacity increase the apparent specific gravity in the range of 1.0 to 1.5, power consumption is greatly increased in the conventional furnace operation.

However, in the case of continuing dissolution after one charge as in the present invention, even if the apparent specific gravity of the charge becomes more than 0.7 ton / m 3, the heat loss generated during charging decreases, thereby reducing the power consumption.

Hereinafter, the present invention will be described in detail through examples.

(Example)

About 150 tons of solid iron source was loaded into the basket, and then charged into an electric furnace having a furnace content of 170 m 3 in two ways. At this time, the present invention is a furnace pipe having an apparent specific gravity of 0.6 ton / ㎥, the dismantled structure scrap of about 1m in length with a carbon concentration of 3.5 ~ 4.5% and the size of about 150 mm × 100 mm × 300 mm, as shown in Figure 6 The charging was carried out in the order of the amount, and in the conventional case, the charging method of the solid iron source and the mold was used twice.

As a result, in the case of the present invention, the apparent specific gravity of the entire charge is 1.32, while in the conventional case, about 0.85, in the case of the present invention, the charge did not overflow to the outside of the electric furnace even with one charge.

Electric operation was carried out in this state of charging, and the time taken from the initial charging to the preparation process after the departure, power consumption and production of raw power units were measured, and the results are shown in Table 2.

division step Conventional example Inventive Example Required time (minutes) One time charge 3 3 1 time melting 15 31 Two times 3 Twice melting 18 Refining 11 11 Leave 3 3 Ready 2 2 Total Time 55 50 Electric power unit (KWh / ton) 390 380 Production per hour (tons / hour) 2.45 2.70

As shown in Table 2, in the case of the present invention, the time required for the second charging time is shortened by about 3 minutes / ch, compared to the conventional electric furnace operation method, and the low power input time is shortened in the secondary melting super boring machine. As the energy input speed was increased and the heat loss emitted to the atmosphere was reduced by opening and closing the furnace roof during the second charging, the dissolution time was reduced by 2 minutes, and the overall operating time was reduced by about 5 minutes. And, in the case of the present invention it can be seen that the productivity by the reduction of the melting time is greatly increased.

As described above, according to the present invention, not only the operation can be performed by one charging when operating the electric furnace, but also the electric power consumption is significantly increased by significantly shortening the melting time of the electric furnace per charge while lowering the power consumption. It can be effected.

Claims (5)

In the electric furnace operation method through charging, melting, refining and tapping of the solid iron source, First, determine the amount of the charge to be charged, the specific gravity of the charge to the following equation 1, [Equation 1] Apparent specific gravity = [charge weight of ton (load)] / [excess factor x volume of electric furnace (㎥)] (However, the excess factor is the volume ratio of the part where the solid content of solid iron source can be filled) A method of rapid melting in an electric furnace, characterized in that it comprises melting and scraping scrap metal so as to be above a defined apparent specific gravity. The method of claim 1, wherein the loading of the scrap scrap and the mold line is charged with a solid iron source of 0.6 ton / ㎥ or less first 10 to 20% of the total amount of charge, and then the mold of a certain size 50 to 100 with respect to the amount of the solid scrap Charging in the range of%, subsequently charging the solid scraps and dies sequentially in the same manner and then dissolving. 3. The method of claim 2, wherein the solid scrap having an apparent specific gravity of 0.6 ton / m 3 or less is pipes or structure dismantle scrap metal. The method according to claim 2, wherein the die is an iron source having a carbon concentration of 1% or more and a size of 200 × 200 × 500 mm or less. The method of claim 1, wherein the excess factor is a fast melting method in the electric furnace, characterized in that a constant in the range of 0.8 ~ 0.9.