KR20020052131A - Insulator for molten iron using by-products in ironmaking processes - Google Patents

Abstract

PURPOSE: A thermal insulator for molten iron using by-products of ironmaking process is provided to obtain an effective thermal insulating method by offering limits of moisture content and use a large amount of blast furnace sludge in case of using as the thermal insulator blended materials of carbon and iron contained by-products. CONSTITUTION: In a thermal insulator comprising a mixture of carbon and iron contained by-products generated in ironmaking process, the thermal insulator for molten iron is characterized in that the carbon contained by-product is one material selected from coke breeze, CDQ(coke dry quenching) dust, and coal dust, the iron contained by-product is one material selected from dust catcher dust, and blast furnace sludge, mixing ratios of the carbon and iron contained by-products are 30 to 50 wt.% and 50 to 70 wt.% respectively, and a moisture content of the mixture of the carbon and iron contained by-products is 12 wt.% or less.

Description

Molten iron insulation using reproductive process by-products {INSULATOR FOR MOLTEN IRON USING BY-PRODUCTS IN IRONMAKING PROCESSES}

The present invention relates to a thermal insulation material using by-products generated in the iron making process in place of the chaff used to prevent the solidification of the molten iron is applied to the surface of the molten iron, more specifically in the coke production process Carbonaceous by-products such as powdered coke, CDQ dust and fine coal powder produced during the drying of coal used in the Corex process, and blast furnace dust By mixing dust collected from dust catcher, iron by-products such as blast furnace sludge, and by-products of so-called steelmaking process, the mixing ratio and water content of by-products can be adjusted to keep the molten iron optimally. It relates to a molten iron insulation material characterized by a limited.

The molten iron produced in the blast furnace steelmaking process is periodically departed through the exit port, and then through tongdo of the columnar torpedo, ladle, etc. It is repaired in the transport vessel of and transported to the steelmaking process. At this time, the insulation material is used for smooth column work by keeping the molten iron and slag remaining in the waterway until the next departure after the completion of the departure.

When the molten iron is described in detail according to FIG. 1 schematically showing the process of repairing after the discharge in the blast furnace, the molten iron (2) standing on the blast furnace bottom (1) is discharged out of the furnace through the outlet (3) While flowing the large hot water (4), it is separated into the molten iron (5) and slag (6) by the specific gravity difference. By the skimmer 7, the slag flows into the slag flowway 8 and the molten iron flows into the molten iron flowway 9. The molten iron is repaired in the repair vessel 10 through the molten iron and then transferred to the steelmaking process to remove impurities in the molten iron.

Usually one blast furnace has two to four outlets, depending on the size of the blast furnace, and after finishing the run through one outlet, block the runway, and then use another outlet to perform the work. Therefore, after one tap is used, the molten iron and slag remain in the tap until the next tap. Therefore, the rice husk is conventionally applied to the melt surface of the inlet portion of the slag tangle (8) to the slag tangle (8) and between the slag tangle (8) and the skimmer (7), and the molten metal (9) inlet at the rear of the skimmer. It prevents the solidification of the melt while not using the turbidity. In addition, when the molten iron in the repair vessel 10 is not repaired full, wait until the next departure and then fill the remaining capacity to move to the next process. Even in such a case, the thermal insulation material is put in order for the molten metal temperature of the surface of the repair container 10 to prevent a fall.

Conventionally, the use of chaff as an agricultural by-product as such an insulating material, the rice cultivation area is reduced, the supply and demand according to this situation is also increasingly difficult to collect.

In order to solve this problem, it has been devised for a method that can be used as a molten iron insulation using carbon-containing iron and iron by-products generated in the iron making process. Among them, a method of mixing sedimentation coke and blast furnace sludge generated in the process of extinguishing red coke with water and using it as a molten iron thermal insulation material ("Method of manufacturing molten iron thermal insulation material in blast furnace operation", Korean Patent Application No. 1998-51432, November 28, 1998), and more specific mixing ratios of the by-products and various methods of using the by-products have been proposed by the present inventors, etc. ("blast furnace lagging insulation, Korean patent application No. 1999-28476", "by-products"). Blast furnace thermal insulation material using, Korean Patent Application No. 1999-63188 "). However, according to the above-mentioned methods, only the types of by-products and their mixing ratios are specified, and the management method of water content when using these by-products having a large change in water content as a molten iron lagging material is not mentioned. There was a limit to using.

In order to solve this problem, the present invention uses dust and bunker coke produced in the CDQ (Coke Dry Quenching) facility and coal dust generated in the corex milling process as carbon by-products, and thus, blast furnace duster dust or blast furnace sludge. It is an object to provide a moisture management method when the iron by-products are mixed with these carbon by-products and the iron by-products and used as a molten iron lagging.

1 is a schematic view of the blast furnace columnar waterway,

Figure 2 is a graph showing an embodiment of the temperature drop when using the thermal insulation material according to the present invention in the ballway furnace;

Figure 3 is a graph showing an example of the change in m value after the insulation coating;

Figure 4 is a chart showing the relationship between the m value according to the change in the moisture content of the insulating material according to the present invention.

In order to achieve the above object, the present invention provides a molten iron thermal insulation material comprising a mixture of carbon by-products and iron by-products generated in the iron making process, wherein the carbon-containing by-products are one of powdered coke, CDQ dust, and coal dust. One of dust catcher dust and blast furnace sludge is used, and the mixing ratio of the carbon-containing by-product and the iron-containing by-product is 30 to 50% by weight: 50 to 70% by weight, and the molten iron thermal insulation material is characterized in that the water content of these mixtures is 12% or less. To provide.

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

Table 1 shows the physical properties of the iron-containing dusts and carbon by-products CDQ dust, buncoke and coal dust generated in the steelmaking process. At this time, the main physical properties of rice hulls, which are currently used as charter insulation materials, were also shown.

Table 1

Main properties of iron, carbon by-products and chaff Particle size (mm) Apparent density (g / cm ³ ) moisture(%) Calorific Value (cal / g) Dust catcher dust 0.2 to 0.3 1.1 to 1.3 10 to 14 - Bag filter dust 0.1 to 0.2 1.4 to 1.8 3 to 7 - Blast furnace sludge 0.04 to 0.08 1.14 to 1.30 15-25 - CDQ Dust 0.1-0.3 0.7 to 0.9 0.6 to 0.9 6700-7000 Bunk coke 2 to 5 0.5 to 0.8 1 to 2 6800-7000 Coal dust 0.1 to 0.2 0.5 to 0.8 10-25 7000 ~ 7500 chaff - 0.08 to 0.09 1 to 2 2400-2700 Remarks Dry density Number at occurrence Dry sample

As shown in the above table, the by-products generated in the steel making process have a large difference in water content and particle size depending on the treatment method and the target material. It is desirable to minimize the moisture content in order to maximize the warming effect, but this requires a separate drying process, which is not recommended considering the cheap use of by-products that are currently problematic for recycling. Judging. In the present invention, the moisture management method and the appropriate coating amount were suggested through the results of the change of the thermal insulation effect in accordance with the change in the moisture content and the coating amount of the three kinds of carbon-containing by-products and the two kinds of iron-containing by-products in the actual process. This will be described below in detail.

As mentioned above, CDQ dust, buncoke and coal dust were selected as carbonaceous by-products and iron-containing dust was selected for dust catcher dust and blast furnace sludge. For blast furnaces with an internal volume of 3800m ³ and four exit ports, the charter temperature from the end of the departure to the next departure at the position of the skimmer (7), the end of the molten iron (9) shown in FIG. The thermal insulation ability was evaluated by measuring the change of. In order to measure the temperature of the molten iron over time, it was measured at regular intervals using a consumable thermocouple, and careful attention was paid to the measurement position and insertion depth so as to be measured under the same conditions every time. The measurement interval was usually 30 minutes. Table 2 summarizes the mixing conditions and moisture content of the embodiment of the present invention.

TABLE 2

Test Operation Conditions of Examples of the Invention number lagging Iron by-product mixing ratio (wt%) Moisture content (%) One chaff - 0.08 2 A + D 60 6.6 3 A + D 60 8.2 4 A + D 60 8.9 5 A + E 60 9.6 6 A + E 60 11.4 7 A + E 60 13.2 8 A + E 60 18.4 9 B + D 60 3.5 10 B + D 60 4.8 11 C + E 60 10.6 12 C + E 60 13.8

Where A is buncoke, B is CDQ dust, C is coal dust, D is dust catcher dust and E is blast furnace sludge.

Figure 2 shows the temperature drop change of the molten iron after applying the insulation according to the conditions of Table 2, the number shown in the figure means the conditions shown in Table 2. As shown in the figure, when the moisture-containing thermal insulation material is applied (for example, 7,8 and 12 times), it can be seen that the thermal insulation ability is very low. At the time, a solidified layer was formed on the surface of the molten iron, which required inconvenient work to remove it. Particularly, since coal dust is very thin, dust generation is a problem when used as a molten iron insulation material, and the compounding ratio is affected. (Example 6 Example conditions of Table 2).

Assuming that the temperature of the molten iron at the bottom of the skimmer is constant at any time, the heat transfer can be interpreted collectively and the following energy balance is established.

Expressed as an expression:

In order to solve the differential equation (3), the following initial conditions are required.

T (t) = T _O , t = 0 (4)

Therefore, the temperature T (t) of the molten iron at an arbitrary time t changes to the exponential function of the elapsed time as follows.

Where Q, V and A are the heat transfer rate through the surface of the molten iron, the volume of the molten iron and the surface of the molten iron, respectively, and Cp and rho are the heat capacity and density of the molten iron. And h is the heat transfer coefficient of the atmosphere, Is the temperature of the atmosphere. In addition, in equation (5), m = Ah / rho CpV.

Based on this, it is possible to analyze the test result by actual test, and the analysis result of one example is shown in FIG. The figure is representative for the condition No. 6 in Table 2. The dimensionless temperature of the horizontal axis in the figure means the left term of equation (5). As can be seen from Eq. (5), the natural logarithm of the dimensionless temperature must be linearly related to the time t, and the slope becomes m . As shown in FIG. 3, there is shown a good linear relationship between the elapsed time after applying the heat insulating material and the natural logarithm value in the left column of the formula (5). Against this background, the thermal insulation ability of various thermal insulation materials may be evaluated based on the value of m . Theoretically, the higher the value of m , that is, the smaller the value of -m , the lower the thermal insulation capacity is, because the temperature of the molten iron drops relatively rapidly.

Table 3 shows the results of the ballast application test as shown in Table 2. mValues and correlation coefficients are summarized, and FIG. 4 shows the moisture content of the mixedmA change in value was shown.

Table 3

M value of Equation (5) calculated based on the temperature change measured by the example number lagging Moisture content (%) m value (1000 / min) Remarks One chaff 0.08 0.3744 2 A + D 6.6 0.4725 3 A + D 8.2 0.4328 4 A + D 8.9 0.5103 5 A + E 9.6 0.5233 6 A + E 11.4 0.5342 7 A + E 13.2 0.6123 Melting surface solidification layer formation 8 A + E 18.4 0.6271 Melting surface solidification layer formation 9 B + D 3.5 0.4240 10 B + D 4.8 0.3928 11 C + E 10.6 0.5411 12 C + E 13.8 0.6435 Melting surface solidification layer formation

As can be seen from Table 3 and FIG. 4, the molten iron has a heat retention capacity of up to about 12%, but if more water is contained, a solidified layer is formed on the molten iron surface. There was a problem that had to be removed. In theory, it would be desirable for the m value of equation (5) to have a value of 0.6 × 10 ⁻³ min ⁻¹ or less.

As described above, according to the present invention, when the carbonaceous by-products of powdered coke, CDQ dust, coal dust and iron by-products such as dust catcher dust and blast furnace sludge are mixed and used as a molten iron thermal insulation material, an effective thermal insulation method is proposed by presenting a limit of moisture content. In addition to providing a large amount of moisture, there is an effect that can use a large amount of blast furnace sludge, which was difficult to recycle.

Claims (1)

In the molten iron insulation material consisting of a mixture of carbon by-products and iron by-products generated in the iron making process, The carbonaceous by-product is one of bunk coke, CDQ dust, coal dust, the iron-containing by-product is one of the dust catcher dust, blast furnace sludge, the mixing ratio of the carbon-containing by-product and iron-containing by-product is 30 to 50% by weight: 50 It is -70 weight%, and the molten metal heat insulating material characterized by the water content of these mixtures 12% or less.