KR100401997B1 - Insulating agent for molten iron in blast furnace - Google Patents

Abstract

The present invention relates to a blast furnace thermal insulation material used to prevent the surface of the molten iron is solidified by coating on the surface of the molten iron, and not only enables the recycling of waste by-products, but also the manufacturing process is simple and manufactured. Low-cost insulation

I want to provide it, and its purpose is.

The present invention is a dust generated in the coke dry cooling system (CDQ): 30-90wt%; At least one member selected from the group consisting of blast furnace dust dust, blast furnace bag filter dust and blast furnace sludge: 10-70 wt%;

Description

Insulating agent for molten iron in blast furnace}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal insulation for blast furnace molten iron which is coated on the surface of molten iron and used to prevent the molten iron surface from solidifying. More specifically, the present invention relates to a CDQ (Coke Dry), a coke dry cooling facility. The present invention relates to a thermal insulation for blast furnace molten metal, which is a mixture of dust produced in a quenching facility and by-products of a steelmaking process such as dust collected in a blast furnace dust catcher.

The molten iron produced in the blast-furnace steelmaking process is repaired and transported to the steelmaking process via the tramway of the columnar after the ship is discharged.

In this process, chaff is used as a heat insulating material to maintain the temperature of the molten iron. In addition, chaff is used to insulate the molten iron and slag remaining in the waterway until the next departure after completion of the departure for smooth column work.

However, as the rice cultivation area is reduced, the amount of rice hulls is decreasing, which causes the collection system to become increasingly unstable. Therefore, fundamental measures are required.

In order to solve this problem, a method of mixing molten iron coke and blast furnace sludge and using it as a molten iron insulator ("Method of manufacturing molten iron insulator in blast furnace operation"; Korean patent application No. 1998-51432; filed November 28, 1998) There is a bar. In this method, however, sedimentation coke and blast furnace sludge containing a large amount of water are used. In order to use them as a heat insulating material, there is a problem in that separate drying is required and a separate crushing process must be performed to reduce the particle size.

In addition, the mixing ratio of sediment coke and blast furnace sludge is specified as 70:30 based on the volume ratio, but the basis for this is not clearly presented.

The present inventors conduct research and experiments to improve the above-mentioned conventional problems,

Based on the results, the present invention was proposed, and the present invention is a waste by-product.

In addition to enabling recycling, the manufacturing process is simple and the manufacturing cost is low.

To provide a thermal insulation material, the purpose is.

1 is a schematic view of the blast furnace columnar waterway and repair vessel

2 is a schematic diagram of an experimental apparatus for evaluating heat insulating properties;

3 is a graph showing the temperature change of the thermocouple 2 according to the elapsed time (minutes) after the thermal insulation material input

4 is a graph showing the temperature change of the thermocouple 1 according to the elapsed time (minutes) after the thermal insulation material input

5 is a graph showing the temperature difference between the thermocouple 1 and the thermocouple 2 according to the elapsed time (minutes) after the thermal insulation material input

6 is a graph showing the change of the area of the temperature difference curve according to the change of the dust catcher dust mixing ratio

Figure 7 is a graph showing the temperature change of the molten iron according to the elapsed time (minutes) after the input of the thermal insulation material in the application of the ballway according to the real

Explanation of symbols on the main parts of the drawings

One . . . . Blast furnace 2. . . . Exit 3. . . . Large bath 4. . . . ship chartering

5. . . . Slag 6. . . . Skimmer 7. . . . Slag Tangdo

8 . . . . Yongsuntangdo 9. . . . Repair container 14. . . . Thermocouple 2

15. . . . Thermocouple 1

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a dust generated in the coke dry cooling system (CDQ): 30-90wt%; At least one selected from the group consisting of blast furnace dust dust, blast furnace bag filter dust and blast furnace sludge: 10-70wt%;

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

The process in which the molten iron is discharged in the blast furnace and then repaired is schematically illustrated in FIG. 1.

As shown in FIG. 1, the molten iron generated in the blast furnace 1 is discharged out of the furnace through the outlet 2 with the slag and then transported through the main bath 3 of the columnar vessel 9. It is repaired and transported to the steelmaking process.

The molten iron and the slag discharged out of the furnace are separated into the molten iron 4 and the slag 5 by the specific gravity difference while the molten iron and the slag flow through the large bathway 3, and the slag 5 is slag bathed by a skimmer 6. As shown in FIG. 7 and the molten iron 4 flows into the molten iron bath 8 separately. The molten iron is repaired in the repair vessel 9 through the molten iron and then transferred to the steelmaking process to remove impurities in the molten iron.

In this process, in order to maintain the temperature of the molten iron, chaff is usually used as a heat insulating material.

That is, one blast furnace (1) has two to four outlets (2) according to the size of the blast furnace, and after the end of the election through one outlet, after blocking the runway using another outlet You will be working on the ship. Therefore, after one tap is used, the molten iron and slag remain in the tap until the next tap. Therefore, the chaff used as the existing molten iron insulation material is applied to the molten surface between the slag tumble furnace (7) and the skimmer (6), and the molten metal at the inlet of the molten melter (8) at the rear of the skimmer. The columnar work is facilitated by preventing the melt from solidifying while the furnace is not in use.

In addition, when the molten iron is not repaired in the repair container, it waits until the next departure and fills the remaining capacity to move to the next process.

Even in this case, in order to prevent the drop of the molten iron temperature on the surface of the repair vessel, rice husk is added as a heat insulating material.

When the rice husk is coated on the surface of the hot melt, ignition and combustion proceed, and the ash remaining after the combustion forms a heat insulating layer to play a role of heat retention.

In order to replace these rice husks, consideration should be given to the fact that the solid thermal insulation material at room temperature is in contact with the hot molten iron surface to lower the surface temperature of the molten iron to prevent solidification and to form an effective insulating layer. It should have, more preferably to use a lot of waste by-products that are not recycled well generated as a process by-product in the current steel mill.

The present inventors refer to a by-product containing combustible carbon components (hereinafter referred to as "carbon-containing by-products") and by-products composed mainly of iron and other inorganic oxides (hereinafter referred to as "iron-containing by-products"). The present invention is conducted on a substance that satisfies the characteristics that the molten iron insulating material should have, and based on the result, the present invention is achieved.

In the present invention, the dust (hereinafter referred to as "CDQ dust") generated in a so-called CDQ facility for cooling dry hot coke produced by dry distillation was selected as a carbon by-product. The sedimentation coke used in the conventional method is a by-product containing a large amount of water because the red coke is cooled by water with water, whereas the CDQ dust contains a very low water content.

However, since the CDQ dust has a small particle size, it has been difficult to recycle until now.

In the present invention, when the CDQ dust is used as a heat insulating material, since it contains less moisture, it utilizes the advantage of no need for additional drying and provides a technique for compensating for the disadvantages of small particle size to increase the heat insulating effect.

That is, the present invention is to solve the problem that a large amount of dust generated by the rapid combustion when using only a small particle size CDQ dust as a heat insulating material by using an appropriate amount of iron-containing dust mixed.

Meanwhile, in the present invention, at least one selected from the group consisting of dust catcher dust, columnar bag filter dust, and blast furnace sludge occurring near the blast furnace process in which the thermal insulation material is used as the iron by-product is selected. Is dust collected in the blast furnace dust jacket, and bag filter dust is dust collected in the blast furnace bag filter.

In the present invention, the content of the CDQ dust generated in the coke dry cooling system is limited to 30-90wt%, which takes into account the thermal insulation capacity and dust generation conditions, respectively. The heat insulating ability of the heat insulating material of the present invention, which is formed by mixing CDQ dust and iron-containing by-products, is similar to chaff which is a conventional heat insulating material up to 6% of water content, but the heat insulating material has a water content of higher than that.

Therefore, the moisture content of the heat insulating material of the present invention is preferably limited to 6% or less.

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

(Example 1)

Table 1 shows the main physical properties of chaff currently used as a molten iron insulation material, Table 2 is a representative value of the CDQ dust, other iron-containing by-products, and sedimentation coke physical properties used in the conventional method contained in the thermal insulation material of the present invention Is shown.

Main properties of rice hulls Chemical composition (% by weight) Calorific value (㎉ / ㎏) SiO ₂ Al ₂ O ₃ CaO H ₂ O 12-15 About 0.5 About 1 915 2500

Main Properties of CDQ Dust and Other Iron By-Products Particle size (mm) Apparent density (g / cm3) moisture(%) Calorific value (㎉ / ㎏) Main composition (%) Dust catcher dust 0.240 1.229 12.5 C 32 Bag filter dust 0.128 1.655 5.7 C 15 Blast furnace sludge 0.058 1.282 20.1 C 27 CDQ Dust 0.213 0.800 0.9 6927 VM 1.45, Ash 12.52 Sedimentation Coke 1.350 0.792 13.1 7084 VM 1.25, Ash 11.54 chaff 0.086 2500 Remarks Density after drying 90 ℃ 24 hours before and after drying weight Dry Sample Standard C: Carbon content VM: Volatile content Ash: Ash content

Experiments were conducted to quantitatively measure the thermal insulation properties of the above-described carbon-containing by-products, CDQ dust and three kinds of iron-containing by-products alone, and mixed samples thereof. Thermal experiments were also conducted on rice hulls currently used as thermal insulation.

At this time, all samples except chaff contain moisture as shown in Table 2, and thermal insulation characteristics experiment using the sample dried at a drying apparatus maintained at 80 ° C for 24 hours to remove the effect of moisture content on the warming effect Was carried out.

The experimental apparatus used for the thermal insulation experiment is schematically shown in FIG. As shown in Figure 2, the experimental apparatus is a container 10 made of refractory, the heating element 11 for heating to a predetermined temperature is inserted in the lower portion, the space for storing a predetermined amount of the measurement sample 13 and the opening and closing in the upper portion The refractory lid 12 is provided and is configured.

Using this apparatus, the thermal insulation properties were measured in the following order.

① With the lid of the sample holder of the device closed, adjust the output of the heating element until the temperature (T2) of the thermocouple 2 (14) becomes 1100 ° C. to raise the temperature.

② When T2 reaches 1100 ℃, open the refractory cap on the upper part of the sample holder, insert the sample quickly and cut off the power of the heating element.

③ Keep the lid open for 180 minutes and record the change in temperature (T1) and T2 of thermocouple 1 (15).

3 to 5 show the results of the thermal insulation obtained by the above experiment.

3 shows the change of the temperature T2 of the thermocouple 2 in the thermal insulation characteristics test results of the rice hull, dust catcher dust and CDQ dust.

As shown in FIG. 3, by injecting a solid thermal insulation material at room temperature into a high temperature container, the temperature is rapidly decreased initially, and after being cooled to the lowest cooling temperature, the heat transfer from the high temperature refractory material constituting the device is again included in the thermal insulation material. The temperature rises again due to the combustion of the carbon component, and after reaching the maximum temperature, the cooling amount of the experimental apparatus increases, and the temperature decreases again.

4 shows the change (in the measurement conditions of FIG. 3) of T1, which is the temperature at the position of the heating element of the thermal characteristics test apparatus.

As shown in Figure 4, regardless of the type of thermal insulation, it can be seen that the temperature is reduced in a substantially constant form.

Figure 5 shows the temperature difference between T1 and T2, the area formed by this change curve is proportional to the amount of heat transferred to the atmosphere through the insulation.

In other words, the larger the area formed by the temperature difference curve, the lower the heat insulating ability.

Table 3 below shows the results of calculating the size of this area based on the thermal characteristics test time of 180 minutes.

Calculation Result of Temperature Change Curve by Insulation Material lagging Area (℃ min) lagging Area (℃ min) chaff 37,958 CDQ Dust 47,892 Dust catcher dust 62,926 CDQ dust + dust capture dust 48,044 Bag filter dust 61,517 CDQ Dust + Bag Filter Dust 48,267 Blast furnace sludge 69,448 CDQ Dust + Blast Furnace Sludge 51,785 Sedimentation Coke 36,213 Sedimentation Coke + Blast Sludge 57,199

Table 3 shows the area of the heat insulating material mixed with CDQ dust and three kinds of iron-containing dust, and the area of the heat insulating material mixed with sedimentation basin coke and blast furnace sludge according to the conventional method. At this time, the mixing ratio was 50:50 based on the weight.

As shown in Table 3, irrespective of the type of the iron-containing by-products to be mixed, the results showed similar results to the thermal insulation properties of the CDQ dust alone, and also improved characteristics than the thermal insulation properties of the iron alone.

CDQ dust as a carbon-containing by-product has been shown to be inferior in thermal insulation properties than the sedimentation coke, but direct comparison is difficult because it is a result of the insulation properties after drying a large amount of moisture contained in the sedimentation coke as described above.

However, it can be seen that the heat insulating material prepared by mixing the CDQ dust and other iron-containing by-products according to the present invention has better heat insulating properties than the mixed heat insulating material of conventional sedimentation coke and blast furnace sludge.

In addition, when using a small particle size of the CDQ dust alone, a lot of dust was generated, even when the dust of about 10% dust dust was mixed it was confirmed that the amount of dust is greatly reduced.

FIG. 6 shows the thermal insulation characteristics based on the area of the temperature change curves of the thermocouples 2 and 1 measured using the above-described thermal insulation characteristics test apparatus when the mixing ratio of the CDQ dust and the dust catcher dust is different.

As shown in FIG. 6, even when the CDQ dust is mixed by 30% by weight and the dust catcher dust is mixed up to about 70%, it can be seen that there is no significant difference in the thermal insulation characteristics.

(Example 2)

Using the blast furnace consisting of four 800 exits and a discharge port of 4800 m2, the molten iron temperature from the end of the departure to the next departure at the position of the skimmer 6, the end of the molten iron furnace 8 shown in FIG. The change of heat insulation capacity was measured and the results are shown in FIG. 7 as the temperature change of the molten iron.

In this experiment, measurements were made at regular intervals using consumable thermocouples to measure the hourly temperature of the molten iron. Careful attention was given to the measurement location and depth of insertion so as to be measured at the same conditions each time. The measurement interval was usually 30 minutes. Table 4 summarizes the experimental conditions.

Conditions tested in the furnace of actual blast furnace number lagging Moisture content (%) Measurement time (minutes) chaff 450 A CDQ dust + blast furnace sludge 13.2 300 B CDQ dust + blast furnace sludge 18.8 270 C CDQ dust + bag filter dust 3.5 240 D CDQ dust + bag filter dust 6.1 360

As shown in Figure 7, it can be seen that as a result of the application of the water treatment for up to 360 minutes, by-products having a low moisture, exhibits a similar thermal insulation effect to chaff, which is a conventional thermal insulation material. On the contrary, when the sludge containing a large amount of water is mixed, it can be seen that the heat insulating ability is bad.

In other words, it can be seen that the mixing of the CDQ dust and the iron-containing dust according to the present invention is superior in the thermal insulation ability than using the sedimentation basin coke containing a large amount of water as a carbon by-product.

As described above, the present invention has an effect of providing an effective thermal insulation material having economical properties similar to rice husks using economic by-products generated in the iron making process.

Claims (2)

Dust from coke dry cooling system (CDQ): 30-90 wt%; At least one selected from the group consisting of blast furnace dust dust, blast furnace bag filter dust and blast furnace sludge: 10-70wt%; The blast furnace molten metal thermal insulation material according to claim 1, wherein the moisture content of the thermal insulation material is 6% or less.