KR100627460B1 - Insulating agent using by-product for molten iron in ironmaking processes - Google Patents

Abstract

The present invention relates to a molten iron insulation to be applied to the surface of the molten iron and used to prevent the solidification of the molten iron, the object of which is the steel mill can be easily obtained while having the characteristics of forming an insulating layer in molten iron It is to provide blast furnace charter insulation using by-products.

The present invention for achieving the above object, blast furnace molten insulation is composed of at least one selected from the group consisting of powder coke: 30% by weight or more, the remaining blast furnace duster dust, blast furnace bag filter dust, blast furnace sludge. ; And,

Coal dust produced in the Korex steelmaking process: 50-80% by weight, blast furnace duster dust, blast furnace bag filter dust, at least one selected from the group consisting of blast furnace sludge: This is a technical summary.

Insulation, chaff, bun coke, coal dust,

Description

Insulating agent using by-product for molten iron in ironmaking processes}

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;

Figure 3 shows the temperature change of the thermocouple 2 according to the elapsed time (min) after the insulation

        Graph

Figure 4 shows the temperature change of the thermocouple 1 according to the elapsed time (minutes) after the thermal insulation material input

        Graph

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

        Graph representing change

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

        Graph showing area change

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 furnace

                   * Description of the symbols for the main parts of the drawings *

                   1 ..... blast furnace 2 ..... exit

                   3 ..... Large bath 4 ..... Charter

                   5 ..... slag 6 ..... skimmer

                   7 ..... slag bath too 8 ..... dragon bath

                   9 ..... Repair container 14 ..... Thermocouple 2

                   15 ..... Thermocouple 1

The present invention relates to a molten iron insulation to be applied to the surface of the molten iron and used to prevent the solidification of the molten iron, more specifically, powder coke or corex generated in the coke manufacturing process ( Corex) The present invention relates to a blast furnace thermal insulation material using by-products such as coal dust generated in the process of drying coal used in the process.

The molten iron produced in the blast furnace iron making process is periodically discharged through the exit port, and then through the Tododo (8) of the columnar torpedo or ladle. It is repaired by a transport container 9, such as a ladle, and transferred to a steelmaking process.

Normally, blast furnaces have two to four outlets, depending on their size, and after finishing the run through one outlet, block the runway, and then use the other outlet to do the work. 1 schematically shows a process in which the molten iron is repaired after being discharged through the outlet in the blast furnace. The molten iron (2) accumulated in the blast furnace bottom (1) is discharged out of the furnace through the outlet opening (3) and separated into the molten iron (5) and slag (6) by the specific gravity difference while flowing through the large bath (4). . 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.

Thus, after one tapping port is used, the molten iron and slag remain in the tap until the next tapping line. Therefore, the insulating material is applied to the molten surface at the inlet of the slag tumbler (8), between the slag tumbler (8) and the slag tumbler (8) and the skimmer (7), and the molten iron trough (9) inlet at the rear end of the skimmer. It is necessary to prevent 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 is transferred to the next process. Even in such a case, the thermal insulation material is put in order to prevent the molten iron temperature of the surface of the repair container 10 from falling.

Conventionally, as an insulating material, chaff, which is an agricultural by-product, was used. However, a decrease in rice cultivation area and a shortage of supply and demand have resulted in a problem of gradually becoming difficult to collect. Table 1 below shows an example of the chemical composition of rice hulls.

Chemical composition (% by weight) Calorific Value (Kcal / kg) SiO ₂ Al ₂ O ₃ CaO H ₂ O 12-15 About 0.5 About 1 9-15 2500

In order to solve this problem, a method of mixing molten coke and blast furnace sludge generated in the process of extinguishing the 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). However, according to this method, in order to use the sedimentation coke and blast furnace sludge containing a large amount of water as a heat insulating material, a separate drying process is required, and a separate crushing process has to be performed to reduce the particle size. In addition, the basis for specifying the mixing ratio of sedimentation coke and blast furnace sludge as 70:30 based on the volume ratio was not clear. And in the actual blast furnace operation requires the insulation of long-term molten iron of 6 hours or more, it should be evaluated based on the thermal insulation performance compared to the existing chaff for a long time, in the above method, the effect of the thermal insulation material based on the thermal insulation effect of only 2 hours Has not been confirmed whether there is practicality.

In order to solve this problem, the present inventors have developed a heat insulating material ("blast furnace molten metal heat insulating material", domestic patent application No. 1999-28476) using the dust generated from the coke dry cooling facility CDQ (Coke Dry Quenching) equipment. However, this insulation has a limitation in use that can be easily applied only in steelworks equipped with CDQ facilities.

The present invention has been devised in a series of research to solve this problem, unlike the previously proposed sedimentation coke or CDQ dust to provide a blast furnace molten material using a by-product that is simple and easy to obtain a manufacturing process, the object There is this.

The first molten iron insulation material of the present invention for achieving the above object is at least one selected from the group of powdered coke generated in the coke manufacturing process: 30% by weight or more, the remaining blast furnace dust dust, blast furnace bag filter dust, blast furnace sludge. It is created.

In addition, the second molten iron insulation material of the present invention is at least one selected from the group consisting of: 50 to 80% by weight of coal dust generated from the Korex steelmaking process, blast furnace duster dust, blast furnace bag filter dust, and blast furnace sludge: 50 to 20 weight It is formulated in%.

Hereinafter, the present invention will be described in detail.

In the case of conventional molten iron insulation material such as rice hulls, when applied to the surface of the hot melt, ignition and combustion proceeds, and the ash remaining after combustion forms a heat insulating layer to act as a heat insulating layer. To replace these chaff,

(1) The solid insulation at room temperature reacts with the molten iron to lower the temperature of the molten iron surface layer to prevent solidification.

(2) the property to form an effective heat insulation layer is required, furthermore,

(3) If it has the characteristics of waste by-products that are generated as process by-products in steel mills and can be easily obtained, they can be ideal molten iron insulation materials.

Based on this aspect, the present inventors select dust generated in the CDQ process as a byproduct containing a combustible carbon component, that is, a carbon byproduct, and together with the byproduct composed of iron and other inorganic oxides as a main component, that is, a byproduct of iron. It has been proposed as a molten iron insulation material composed of one or more selected from the group of dust catcher dust, columnar bag filter dust and blast furnace sludge occurring near the blast furnace process.

However, since the dust generated in the CDQ process as the carbon by-product is a by-product not available in steel mills employing a process of wet digestion of coke, it does not satisfy the requirements of (3).

Accordingly, the present inventors continue to search for carbon-containing by-products that satisfy the requirements of (1) and (2) and fully satisfy the requirements of (3). Experiments have shown that coal dust from the process meets these conditions. The mixing ratio of the molten iron insulation material varies according to the type of carbon-containing by-products, and for convenience, the first molten iron insulation material will be referred to as the first molten iron insulation material if the powdered coke is used as a raw material, and the second molten iron insulation material will be described separately.

[1st Charter Insulation]

In the coke manufacturing process, coke is broken down during the blast furnace transport process or sieving for use in the blast furnace, and powder coke below a certain size is generated. In the present invention, these powdered coke is used as a carbon by-product, which is also used as a fuel in some sintering processes. However, although finely divided coke is used in combination with raw coal to produce coke again, the coke produced in this manner is reluctant to use because of poor quality.

In the present invention, the powdered coke generated in the coke production process and at least one selected from the group consisting of blast furnace duster dust, blast furnace bag filter dust, blast furnace sludge is mixed to obtain a blast furnace thermal insulation material. If the powdered coke contains 30% by weight or more, the coke exhibits insulation properties equal to or higher than that of the rice husk. Indeed, the higher the content of powdered coke, the better the thermal insulation properties, but it is technically significant to increase the amount of these additives in terms of recycling of iron by-products, and to make the thermal insulation properties similar to rice hulls. Add up to 70% dust, blast furnace sludge.

[2nd chartered insulation]

As a new molten iron production process rather than a blast furnace process, one of the new processes being adopted and operated in several steel mills recently is the Corex process, which feeds raw coal, not coke, directly into the melting furnace. In the step of drying the raw coal, fine coal dust (hereinafter referred to as "coal dust") is generated. The coal dust generated in this way may be used in combination with the pulverized coal for blast furnace injection when the blast furnace process is operating together, but in this case, there is a limitation in the complete recycling due to the need for a separate transportation process.

In the present invention, when the coal dust is used as a carbon by-product, the content thereof is 50 to 80% by weight, and at least one selected from the group consisting of the remaining blast furnace dust dust, blast furnace bag filter dust, and blast furnace sludge. This is because the content of coal dust should be more than 50% to ensure the thermal insulation characteristics of the conventional rice hull insulation material, because if the amount is more than 80% dust generation too much.

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

Example 1

Table 2 below shows the typical properties of the iron-containing dust generated in the blast furnace process and the physical properties of the CDQ dust and sedimentation coke used in the conventional carbon-containing by-products and the two kinds of carbon-containing by-products used in the present invention.

Particle size (mm) Apparent density (g / cm3) moisture(%) Calorific value (kcal / kg) Major composition (%) Dust catcher dust 0.240 1.29 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 Bunk coke 3.047 0.627 1.5 7008 VM 1.19, Ash 10.92 Coal dust 0.116 0,620 18.8 7092 VM 29.43, Ash 12.22 chaff - 0.086 - 2500 Remarks Density after dry 90 ℃ 24 hours before and after drying Dry Sample Standard C: carbon content VM: volatile content Ash: ash content

Using the experimental apparatus (FIG. 2) shown in Korean Patent Application No. 1999-28476, the powdered by-products of coke dust and coal dust were used, and three kinds of iron-containing by-products alone and their mixed samples were tested for thermal properties. In addition, a thermal characteristic test was also carried out for rice hulls currently being used as a heat insulating material.

The apparatus used for the thermal insulation experiment is shown schematically in FIG. 2. The experimental apparatus is a container 10 made of refractory, and a heating element 11 is inserted into the lower portion of the container 10 for heating to a predetermined temperature, and a refractory lid 12 capable of opening and closing in a space in which a predetermined amount of the measurement sample 13 is placed and in the upper portion thereof. It is provided and 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 and increase 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).

Insulation results obtained by the above experiment are shown in FIGS. 3 to 5.

Figure 3 shows the change in temperature (T2) of the thermocouple 2 in the thermal insulation characteristics test results of rice husk, powdered coke, coal dust, CDQ dust and dust basket dust. At this time, all samples except chaff contain moisture as shown in Table 2, and the thermal insulation characteristics using the sample dried for 24 hours in a drying apparatus maintained at 80 ℃ to remove the effect of the moisture content on the warming effect The experiment was conducted.

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, it is again included in the heat transfer from the high temperature refractory constituting the device and the thermal insulation material. The temperature rises again due to the combustion of the carbon component, and the like, and after reaching the maximum temperature, the cooling amount of the experimental apparatus increases, and the temperature gradually decreases again.

4 shows the change (in the measurement conditions of FIG. 3) of T1, which is the temperature at the position of the heat generator of the thermal characteristics test apparatus. As shown in Figure 4, regardless of the type of thermal insulation, it was found that the temperature is reduced to 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 during the same time, 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.

lagging Area (℃, min) lagging Area (℃, min) chaff 37,958 Buncoke + Dust Knit Dust 42,589 Dust catcher dust 62,826 Buncoke + Bag Filter Dust 47,817 Bag filter dust 61,517 Buncoke + Blast Sludge 45,551 Blast furnace sludge 69,448 Coal Dust + Dust Catcher Dust 34,747 Sedimentation Coke 36,213 Sucton Dust + Bag Filter Dust 37,628 CDQ Dust 47,892 Coal Dust + Blast Furnace Sludge 37,232 Bunk coke 25,178 CDQ Dust + Dust Catcher Dust 48,044 Coal dust 33,358 Sedimentation Coke + Dust Captured Dust 57,199

Table 3 shows the temperature change area of thermal properties of thermal insulation material mixed with powdered coke, coal dust and three kinds of iron-containing dust, and the area of thermal insulation material mixed with conventional methods such as CDQ dust + dust basket dust, sediment coke + blast furnace sludge. Calculated and shown together. At this time, the mixing ratio was 50:50 based on the weight.

As shown in Table 3, in general, the use of carbon-containing by-products alone was superior to the iron-containing by-products. In addition, when carbon-containing by-products are powdered coke, the heat insulating capacity is greatly reduced by mixing three kinds of iron by-products, whereas in the case of coal dust, the thermal insulation properties of coal dust alone are similar regardless of the type of iron by-products mixed. It shows the characteristics that indicate. However, such a laboratory evaluation is difficult to make a direct comparison because it is a result of heat retention after drying the moisture as described above.

However, powdered coke and coal dust alone or mixed thermal insulation materials of these carbon-containing by-products and iron-containing by-products according to the present invention is equivalent to or better than the thermal insulation materials of conventional sedimentation coke and blast furnace sludge or mixed thermal insulation of CDQ dust and duster dust. It can be seen that.

In addition, when only a small particle size of coal dust is used alone, a lot of dust was generated, and when 20% of the dust catcher dust was mixed, the amount of dust was greatly reduced.

6 is a thermocouple 2 and the thermocouple 1 of the thermal insulation characteristics measured by the thermal insulation characteristics experimental apparatus when mixing the dust-coated dust and the dust-coated dust by-products of coke dust and carbon dust of the present invention It is based on the area of the temperature change curve. As shown in Figure 6, when the powdered coke and coal dust mixed with the dust catch dust up to 30% and 50% by weight, respectively, it can be seen that the equivalent or excellent heat retention compared to chaff. However, when more than 80% of coal dust is used, dust generation is extremely severe, indicating undesirable characteristics.

Example 2

In the blast furnace composed of 4 800 outlets and 4 outlets, the thermal insulation capacity was measured by measuring the change of the molten iron temperature from the end of the starting point to the next starting point at the position of the skimmer (6), the end of the molten iron (8) shown in FIG. It evaluated, and the result is shown by the temperature change of molten iron in FIG.

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 examples according to the present invention.

number lagging Iron by-product mixing ratio (% by weight) Moisture content (%) Measurement time (minutes) Remarks - chaff _ 450 Conventional example A CDQ Dust + Blast Furnace Sludge 70 13.2 300    " B      " 60 18.8 270    " C CDQ Dust + Bag Filter Dust 70 3.5 240    " D      " 70 6.1 360    " E Buncoks + Duster Dust 70 7.1 410 The present invention F Buncoke + Bag Filter Dust 70 2.9 300    " G Buncoke + Duster Dust 60 6.6 240    " H Coal Dust + Bag Filter Dust 60 3.1 250    " I Coal Dust + Bag Filter Dust 40 2.8 360    "

As shown in Figure 7, it can be seen that as a result of the application of the hot water for up to 410 minutes, by-products having a low moisture content exhibit 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 rather bad. In addition, compared with the thermal insulation material mixed with the CDQ dust and iron by-products can be confirmed through the results of applying similar or excellent thermal insulation properties to the actual blast furnace water.

As described above, according to the present invention, it is possible to provide an economical and effective thermal insulation using the by-products generated in the steelmaking process exhibiting the thermal insulation properties similar to the existing thermal insulation using chaff or CDQ dust.

Claims (2)

delete Coal dust produced in the Korex steelmaking process: 50 to 80% by weight and at least one selected from the group consisting of blast furnace duster dust, blast furnace bag filter dust and blast furnace sludge:

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