KR100466499B1 - Method for manufacturing the sintering ore having excellent anti-reduction - Google Patents

Abstract

The present invention relates to a sintered ore which is mixed with iron ore and coke into a blast furnace and charged as a raw material. In order to maintain a reduction rate of sintered ore at 68 to 70%, a serpentine rock is added at a content of 2.70 to 3.35 wt% and the reduction rate of the sintered ore is Serpentine rock is added in an amount of 2.12 to 2.70 wt% to maintain 70 to 72%, and serpentine rock to an amount of 3.35 wt% or more or 2.12 wt% or less to maintain the reduction rate of sintered ore at 68% or less. It is added to improve the reduction rate of the sintered ore while securing the low temperature reduction differentiation rate and rotational strength, which is the quality control index of the sintered ore, by adjusting the addition amount of serpentine rock, that is, MgO component to adjust the reduction rate of the sintered ore By reducing the content of slag contained in the sintered ore, the low temperature reduction rate and rotational strength of the sintered ore are kept constant while the breathability This improves the manufacturing cost of the molten iron.

Description

Method for manufacturing sintered ore with excellent reducing ability {Method for manufacturing the sintering ore having excellent anti-reduction}

The present invention relates to a sintered ore mixed with iron ore and coke in a blast furnace and charged as a raw material, and in particular, to reduce the sintered ore's reduction rate by controlling a component of magnesium oxide added as a slag component in the sintered ore. A method for producing a sintered ore.

In general, the sintered ore is charged as a heat source of the blast furnace by mixing the subsidiary materials such as limestone, silica sand, serpentine, quicklime and the like as a main source of iron ore in an appropriate ratio, and the sintered ore is maintained as it is to the bottom of the blast furnace It is important to ensure breathability so as to descend smoothly.

In recent years, however, in order to reduce the manufacturing cost of molten iron, attention has been focused on the use of pulverized coal production and low-cost raw materials, and this has been included in the sintered ore under the condition that the air permeability of the sintered ore charged into the blast furnace is maintained. A method for reducing the content of slag has been studied.

However, increasing the injection rate of pulverized coal means that the amount of charged coke charged into the blast furnace is reduced, which is directly connected to the deterioration of the air permeability in the blast furnace. In order to reduce the content of + SiO 2 + MgO), it is desired to improve the reduction rate of the sintered ore.

On the other hand, the main components of the sintered ore is shown in Table 1, and recently has been reducing the content of slag to 14.5%. This decrease in slag content is a major deterioration of strength and cold reduction differentiation rate (DRI), the quality control index of sintered ore, and in particular, the deterioration of strength and differentiation rate acts as a deterrent to breathability in the blast furnace.

Therefore, in the sintering industry that manufactures sintered ore, in order to compensate for the reduction of slag content that acts as a binder of iron ore, the efforts to improve the quality index of sintering by increasing the sintering reaction temperature by injecting high caloric content into iron ore, This has a problem of raising the manufacturing cost of the sintered ore.

Therefore, when the heat source necessary for the reaction in the sintering operation is sufficient, the magnesium oxide (MgO) forms a high melting point slag, inducing the sintering reaction at high temperature by adding serpentine rock, so that the content of residual magnetite after sintering ore production is increased. There has been proposed a method of improving the low temperature reduction differentiation with increasing.

However, the method of adding serpentine rock in the sintering operation of manufacturing sintered ore is not suitable for the low cost of reducing the manufacturing cost of the sintered ore. Therefore, the quality control method of the sintered ore is improved in low temperature reduction differentiation (RDI). Attention is being paid to improving the reduction rate (RI).

Accordingly, the present invention has been made in order to solve the problems described above, the production of sintered ore excellent in the reducing ability to improve the reduction rate of the sintered ore by controlling the component of magnesium oxide which is added as a slag component in the sintered ore The purpose is to provide a method.

1 is a schematic view showing a sintered ore maker according to the present invention,

Figure 2 is a ternary state diagram for the main components of the sintering reaction according to the present invention,

3 is a view showing a comparison of the quality of the sintered ore to the ratio of magnesium oxide according to the present invention.

Explanation of symbols on the main parts of the drawings

10: sintering machine 11: particle size classifier

12: blended raw material 13: sintering pot

14: negative pressure line 16, 18: thermocouple

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings and tables.

1 is a schematic view showing a sintered ore maker according to the present invention, Figure 2 is a ternary state diagram for the main components of the sintering reaction according to the present invention, Figure 3 is the quality of the sintered ore to the ratio of magnesium oxide according to the present invention As a figure showing the comparison, the air permeability of the sintered ore is adjusted by adjusting the component of the serpentine which is a magnesium oxide source (MgO source) which is charged as a slag component into the sintered ore charged in the blast furnace and managed with a reduction rate (RI) of about 65 to 75%. In providing a method for producing a sintered ore having excellent reduction property while ensuring a reduction rate (RI), in order to maintain a 68 to 70% reduction rate of the sintered ore, serpentine is added in an amount of 2.70 to 3.35wt%, and In order to maintain a reduction rate of 70 to 72%, serpentine rock is added in a content of 2.12 to 2.70 wt%, and in order to maintain a reduction rate of sintered ore to 68% or less or 72% or more The serpentine rock is added in an amount of 3.35wt% or more and 2.12wt% or less, thereby improving the reduction rate of the sintered ore while securing low temperature reduction differentiation rate and rotational strength, which are the quality control index of the sintered ore.

As shown in FIG. 1, the sintering machine 10 is equipped with a sintering port 13 filled with the compounding material 12 on the upper side of the particle size classifier 11, and both side walls of the size classifier 11. The negative pressure line 14 and the lower thermocouple 18 for measuring the exhaust gas and the temperature generated during the sintering process are mounted. In addition, an upper thermocouple 16 for measuring the temperature of the blended raw material is attached to the side wall of the sintering port 13.

Of course, the sintering machine 10 is connected to a computer (not shown) so as to obtain data on-line by measuring the negative pressure or the temperature and flow rate of the exhaust gas generated during the sintering process. It is added that the inner volume of the sintering pot 13 was 200 mm x 600 mm.

At this time. The standard raw materials used in the sintering machine 10 were used by mixing the components having the composition shown in Table 1, wherein the ratio of the powdered coke and semi-glossy in the standard raw materials to maintain around 3.8wt% and 18.0wt% relative to the total weight ratio, respectively. It was.

TABLE 1

Sample ironstone FeO Al2O3 CaO SiO2 MgO cokes Slag 60.0 6.3 1.5 8.3 4.8 0.8 to 1.5 1.73 13.9-14.6

In addition, the target component values of the sintered ore are shown in Table 2, and under the conditions that the content of slag (CaO + SiO 2 + MgO), that is, the basicity is the same, the addition ratio of sub-materials and powdered coke (calories) is adjusted according to the experimental purpose. It was.

TABLE 2

Iron ore One 2 3 4 5 6 Compounding ratio (wt%) 11.7 8.78 10.73 32.00 10.56 18.00 Subsidiary Materials and Fuel One 2 3 4 5 Compounding ratio (wt%) 10.56 1.48 0.54 1.48 3.80

In addition, the operating conditions of the sintering machine 10 in the course of the sintered ore manufacturing test (pot test) are as shown in Table 3. At this time, the sintered ore manufactured in the sintering machine 10 was tested using the reduction rate measurement method of the sintered ore determined in JIS, the method is as follows.

TABLE 3

Test Condition value Zhang Mouth Port size 200mm.dia × 600mmH Compound weight 35 ~ 37Kg Ignition Temperature 1100 ℃ time 2 minutes Suction pressure At ignition -1000Aq Upper part Height 30 mm Granularity 10-15mm

In other words, the test conditions, 500g (particle size: 15 ~ 20mm) dried at 105 ± 5 ℃ for 60 minutes or more in an electric furnace, CO: 30%, N2: 70% at 900 ℃ 15 Nl / min. The weight was measured after reducing for 180 minutes while passing at a flow rate.

At this time, the calculation formula of the reduction rate (RI) is as follows.

* RI = {(WO-WF) / WI x (0.43 x A-0.112 x B)} x 10 ⁴

Where RI is reduction rate (%)

WI: sample volume (g)

WO: sample weight before initiation of reduction (g)

WF: sample weight after reduction (g)

A: T.Fe (%) of the sample before reduction

B: FeO (%) of the sample before reduction

In addition, the method of measuring the rotational strength (TI) and the low temperature reduction rate (RDI) of the sintered ore can be obtained through the following equation.

In the present invention, the average value of the sintered ore manufactured by the sintering machine 10 was taken through five or more analytical processes, and the sintered ore was changed while changing the amount of serpentine which is a magnesium oxide source (MgO source) added to the sintered raw material. It is added that the manufacturing test was performed. Of course, the quality changes of the sintered ore according to the mixing ratio of the powdered coke were also considered in the fixed condition of the serpentine rock.

As shown in Table 2, the target composition of each chemical component in the sintered ore, by adjusting the amount of serpentine rock in a state in which aluminum oxide (Al 2 O 3) and basicity (CaO / SiO 2) were fixed, changing the amount of MgO added step by step, The reduction rate of the sintered ore according to the MgO change was analyzed, and the effects on the rotational strength (TI) and the low temperature reduction differentiation (RDI) were also analyzed.

[Comparative Example]

Table 4 shows the results of comparing the quality according to the change of MgO component in the state of fixing the content of powdered coke (calorie) and slag (base) of the sintered ore. As can be seen from Table 4, the quality of the sintered ore deteriorated as the MgO content was increased, which means that the melt generation temperature, which leads to the binding of iron ore in the sintering reaction, moved to a high temperature due to the increase in the MgO content.

TABLE 4

MgO content (wt%) 0.8 1.0 1.2 1.5 Powdered coke (wt%) 3.8 Slag content (wt%) 13.9-14.6 Reduction rate (RI.%) 72 71 69 67 Low temperature reduction differentiation (RDI.%) 37 37 39 41 Rotational Strength (TI.%) 70 69 66 65

These results can be seen in the ternary state diagram drawn based on the main components of the sintering reaction shown in FIG. That is, the composition for producing slag of low melting point in the sintering reaction is the same as in Figure 2, the iron ore is combined by the melt produced within about 1200 ~ 1300 ℃ by appropriate mixing and basicity adjustment.

However, in the state as shown in FIG. 2, when the content of the MgO component is increased, the melting point of the slag is increased to move to the magnetite-generating region, which means that the rise of the low melting point slag is relatively decreased.

Of course, when the amount of heat required for the sintering reaction is sufficient, that is, when the amount of powdered coke is sufficient, it is possible to improve the low-temperature reduction differentiation rate (RDI) according to the increase of magnetite in the sintered ore. Since the differentiation rate cannot be improved, the effect of increasing the amount of MgO component added is eliminated.

Table 5 shows the changes in the constituent mineral phase of the sintered ore according to the change in the content of the MgO component, magnetite in the sintered ore only when the amount of serpentine is increased, that is, when the amount of MgO component is increased and the amount of powdered coke is increased. It can be seen that the content of is increased.

TABLE 5

MgO (wt%) Coke (wt%) hematite magnetite Coke-iron Ore Slag 0.8 3.8 30 16 38 16 1.0 25 18 41 16 1.2 27 18 38 17 1.5 30 17 39 14 0.8 3.5 30 16 40 14 1.0 3.8 25 18 41 16 1.2 4.0 23 23 37 17 1.5 4.2 21 31 31 17

Therefore, in the present invention, by presenting the appropriate addition ratio of MgO in the production of such low slag low fuel sintered ore, it was intended to derive the manufacturing conditions of the sintered ore excellent in reducibility but does not adversely affect other quality.

FIG. 3 is a graph showing the quality change according to the MgO component of the sintered ore under the condition that the basicity and the powdered coke have the same mixing condition. As shown in Table 4, all the quality is deteriorated as the MgO increases. . This trend was very straightforward and is represented by the regression equation.

* RI: y (RI) = -8.0357 × (MgO, wt%) + 78.804 (R2 = 0.9784)

* RDI: y (RI) = 6.25 × (MgO, wt%) + 31.25 (R2 = 0.9259)

* TI: y (TI) = -7.0833 × (MgO, wt%) + 76.083 (R2 = 0.9276)

In other words, the correlation of the quality of the sintered ore according to the change of the MgO component in the same raw material conditions can be expressed by the above equation. Therefore, the MgO compounding ratio for satisfying the quality conditions of the sintered ore in the blast furnace can be set, the results are shown in Table 6.

TABLE 6

Reduction rate (RI.%) MgO content (wt%) Low temperature reduction differentiation (RDI) Rotational strength (TI) 〉 68 〈1.34 〈39.6 〉 66.6 〉 70 〈1.09 〈38.1 〉 68.4 〉 72 〈0.85 〈36.6 〉 70.1

As can be seen from Table 6, the quality index required in the blast furnace can be adjusted as desired according to the MgO component management, and the deterioration of the air permeability due to the high pulverized coal blowing operation can be prevented by charging the sintered ore with high reduction rate into the blast furnace. Will be.

TABLE 7

Reduction rate (%) MgO content (wt%) Serpentine (wt%) Low temperature reduction differentiation Rotational strength 〉 68 <1.34 〈3.35 〈39.6 〉 66.6 〉 70 〈1.09 <2.70 〈38.1 〉 68.4 〉 72 〈0.85 〈2.12 〈36.6 〉 70.1

Therefore, as shown in Table 7, in the actual operation of the blast furnace, the reduction rate (RI) is managed at about 65 to 75%, so that the amount of serpentine, that is, the MgO component, is properly adjusted to maintain low temperature reduction differentiation, rotational strength and breathability. At the same time, it is possible to adjust the reduction rate of the sintered ore.

As described above, according to the manufacturing method of the sintered ore excellent in the reducing property according to the present invention, the amount of serpentine, that is, the reduction rate of the sintered ore is increased by adjusting the composition of magnesium oxide to reduce the content of slag contained in the sintered ore. Therefore, while maintaining the low-temperature reduction differentiation rate and rotational strength of the sintered ore constant, the air permeability is improved to reduce the manufacturing cost of the molten iron.

Claims (1)

By adjusting the components of the serpentine, which is a magnesium oxide source (MgO source), which is charged as a slag to the sintered ore charged in the blast furnace and managed with a reduction rate (RI) of about 65 to 75%, the ventilation rate of the sintered ore is ensured and the reduction rate is improved. In providing a method for producing a sintered ore excellent in reduction property, Serpentine rock is added at a content of 2.70-3.35 wt% to maintain the reduction rate of the sintered ore at 68 to 70%, and serpentine rock is added at a content of 2.12 to 2.70 wt% to maintain the reduction rate of the sintered ore at 70 to 72%, In order to maintain the reduction rate of sintered ore to 68% or more and 72% or more, serpentine rock is added in the content of 3.35wt% or more and 2.12wt% or less to secure the low temperature reduction rate and rotational strength, which is the quality control index of sintered ore, A method for producing a sintered ore excellent in reducing properties, characterized by improving the reduction rate.