KR100433252B1 - Iron ore sintering method having coke concentration gradient - Google Patents

Abstract

In the present invention, in the sintering of iron ore using a dwight-roid type sintering machine, a gradient is given to the concentration of coke in the raw fuel mixture charged in the sintering bogie so that the coke is not included in the lower sintering bogie so that the calorific value in the bottom of the sinter bogie It provides an iron ore sintering machine and iron ore sintering method to reduce the amount of pollutants generated by reducing the.

Description

Iron ore sintering method having coke concentration gradient

The present invention provides a concentration gradient of coke to the raw material fuel mixture layer formed in the sintered bogie to simultaneously reduce sulfur oxide (SOx) gas, nitrogen oxide (NOx) and carbon dioxide gas generated during iron ore sintered ore production without degrading the quality of the sintered ore. The present invention relates to an iron ore sintering method having a concentration gradient of coke.

Dwight-Lloyd type sintering process in which fine iron ore is sintered to produce a sintered ore of the size suitable for a blast furnace is generally coke or a coke or A raw fuel mixture containing anthracite coal in a proportion is used. The pre-processed raw fuel mixture through the mixing and assembly process is supplied to the sintering bogie 1 of the Dwight-roid type sintering machine as shown in FIG. 1, which is connected to the crawler wheel 4 to rotate. It is.

Therefore, when the sintered trolley 1 passes below the upper square hopper 6, the upper light is first charged to the bottom of the sintered trolley 1 to form an upper light layer, and then the raw fuel mixture hopper 7 continues. When passing below, the raw fuel mixture is charged onto the upper light layer to form the raw fuel mixture layer. The sintered trolley 1 comprises a bottom surface of the side wall 2 and the grate 3, as shown in FIG. 3, the grate 3 facilitates the supply of air for combustion during sintering.

Through the grate (3) to the bottom of the sintered trolley (1) is put the lump ore to prevent the raw material fuel mixture mainly in powder form, which is called the upper light.

After charging the raw fuel mixture, the upper part of the raw material fuel mixture layer is ignited by the ignition device in the ignition furnace 12, and the air is continuously sucked from the lower part of the sintered bogie 1 via the wind box 5 so as to feed the raw fuel. As the coke or anthracite in the mixture layer burns, the flame continuously proceeds downward to form a combustion zone, whereby iron ore and limestone react with each other to produce a solution, and the solution binds the finely divided iron ores to each other.

The wind box 5 is connected to the main exhaust pipe 13 is provided with an electrostatic precipitator 14, a blower 15, etc., the main exhaust pipe 13 is connected to the chimney 16 for the discharge of sintered exhaust gas. .

After the sintering is completed to the lower part of the combustion zone and the sintering is completed, the sintered cake is discharged from the sintered trolley 1 and crushed into a particle size suitable for the blast furnace and supplied to the blast furnace.

As shown in FIG. 2, the raw material fuel mixture is charged into the sintered trolley 1, and a plurality of raw material hoppers 8 each containing iron ore, limestone, silica and quicklime, and a fuel hopper 9 containing coke. Raw material and coke as fuel are supplied to the mixer 10, the raw material and coke are mixed in the mixer 10, and then supplied to the raw material fuel mixture granulator 11 and then the raw material fuel mixture granulator 11 It is fed into the fuel mixture loading hopper 7, and the raw material fuel mixture is comprised so that it may be charged to each sintering cart 1 from the raw material fuel mixture loading hopper (7).

Meanwhile, as the sintering process proceeds, carbon dioxide (CO ₂ ), which is of increasing interest in recent years, is generated due to sulfur oxides (SOx), nitrogen oxides (NOx), and global warming, which are environmental pollutants. Efforts are ongoing.

First, there is no method specifically proposed or designed to reduce sulfur oxides (SOx), but the upper light is replaced with limestone, or the existing upper light and limestone are mixed and used as the upper light to fix the sulfur oxides generated during sintering. Methods, elements, and the like.

There are several ways to reduce NOx.

First, nitrogen oxides in the sintering process by replacing anthracite coal used as fuel with low-nitrogen anthracite coal or by coagulating coal at high temperature to induce organic nitrogen compounds in coke to a material such as aluminum nitride (AlN) having a low conversion rate to nitrogen oxides. How to reduce the occurrence,

Secondly, a method of suppressing the conversion rate of nitrogen in the coke to nitrogen oxide by raising the coke combustion temperature by raising the preheating and ignition temperature of the raw fuel mixture, and eventually forming a reducing atmosphere by increasing the carbon monoxide (CO) gas generation rate;

Third, the conversion rate of nitrogen in the fuel is converted to nitrogen oxides by increasing the particle size of the raw fuel mixture to improve the air permeability during sintering to improve the combustibility of the coke and the increase of the carbon monoxide / oxygen ratio (CO / O ₂ ). How to reduce,

Fourth, the method of suppressing the generation of nitrogen oxides by showing the same effect as when the ignition temperature is increased by the effect of increasing the combustion temperature obtained by allowing the combustion of the coke proceeds from the surface to the inside through the increase of the particle size of the coke, and

Fifth, the combustion temperature of coke is increased by exothermic reaction by addition of lower iron oxides such as mill scale, thereby increasing the amount of carbon monoxide generated during the combustion of coke, and also burning by oxidation of lower iron oxide itself. For example, a method in which the oxidative atmosphere is weakened in the vicinity of the coke burning zone due to a decrease in the oxygen partial pressure in the air, such that nitrogen in the fuel cannot be easily oxidized to nitrogen oxides.

In addition, with regard to carbon dioxide reduction, there is no special method other than the method of reducing the content of coke and anthracite coal used as fuel in the sintering process.

The method of using low nitrogen anthracite coal, which is used as a method of reducing nitrogen oxide, is not only stable supply of low nitrogen anthracite coal, but also increases the generation of chlorine-based gas, which is an environmental pollutant. The concentration of oil in the dust collector 14 may be a problem due to the evaporation of the volatile material.

In addition, the method of increasing the preheating and ignition temperature of the sintered raw material is effective, but there is a disadvantage that high energy costs are consumed due to preheating.

The method of reducing nitrogen oxides by increasing the particle size of the raw fuel mixture has a problem in that the raw material cost burden is increased because the import cost is higher in the case of iron ore, which is the main raw material, compared to the spectroscopy.

In order to reduce the amount of nitrogen oxide generated by increasing the particle size of the coke, the problem of selecting an appropriate coke particle size and the coke supply / demand method become a problem.

And efforts to reduce the nitrogen oxides using the mill scale has a problem of fire and performance degradation of the electrostatic precipitator 14 due to the oil contained in the mill scale requires attention to use.

In addition, there is a problem in that additional cost burden occurs when replacing the top light with limestone to reduce the existing sulfur oxides.

On the other hand, when analyzing the mechanism of sintering in the research process for the reduction of sulfur oxides and nitrogen oxides, after charging the raw fuel mixture, the ignition device in the ignition furnace 12 to ignite the upper portion of the raw material fuel mixture layer by the ignition device and at the bottom If the suction continues, the coke or anthracite in the raw fuel mixture layer is burned, and the flame continuously proceeds downward, and the iron ore and limestone react with each other to produce a solution, and the solution combines the fine iron ores to form a sintered ore, Due to the nature of the sintering operation, it was found that heat accumulation in the lower part than the upper part is a general phenomenon.

In the sintering process, the sulfur oxide starts to occur rapidly when the combustion zone proceeds to the lower portion of the sinter bogie 1 and the wet zone of the lower raw material of the sinter bogie 1 disappears.

The generated sulfur oxide is collected by the calcium oxide (CaO) component contained in the limestone or quicklime contained in the raw fuel mixture, and is present in the form of calcium sulfate (CaSO ₄ ).

At this time, the reaction mechanism is as follows.

CaO + SO ₂ + 1 / 2O ₂ → CaSO ₄

However, in the case of the calcium sulfate produced in this way, since it is re-decomposed to generate sulfur oxides at 1,250 ° C or higher, it is necessary to reduce the amount of heat in the lower layer of the sintered trolley (1).

In the case of nitrogen oxides, since most of them are caused by anthracite coal used as fuel and nitrogen contained in coke, it may be necessary to use low nitrogen anthracite coal or to reduce the amount of coke itself to reduce nitrogen oxides.

In addition, the present invention provides a process for producing iron ore sintered ore without mixing the raw material fuel mixture and charging into the sintered cart, by adjusting the distribution of coke without increasing the high energy cost and raw material purchase cost due to preheating, etc., and without deteriorating the quality of the sintered ore The present invention provides an iron ore sintering method capable of simultaneously reducing the amount of sulfur oxides (SOx), nitrogen oxides (NOx), and carbon dioxide generated in the air.

1 is a schematic view showing a conventional Dwight-roid type iron ore sintering machine.

FIG. 2 is a block diagram showing an input system of raw materials and fuel used in the sintering apparatus of FIG. 1.

3 is a perspective view schematically illustrating a sintering cart used in the sintering apparatus of FIG. 1.

Figure 4 is a schematic diagram showing a wrought-roid type iron ore sintering machine according to the present invention.

FIG. 5 is a diagram illustrating a system of input of raw materials and fuel used in the sintering apparatus of FIG. 4.

6 is a side cross-sectional view showing a state where a raw fuel mixture is charged by a conventional sintering machine.

7 is a side cross-sectional view showing a state in which a raw fuel mixture is charged to have a concentration gradient of coke according to one specific embodiment of the present invention.

8 is a side cross-sectional view showing a state in which a raw fuel mixture is charged to have a concentration gradient of coke according to another specific embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

1: sintered truck 2: side wall

3: grate 4: caterpillar wheel

5: windbox 6: upper square hopper

7: Raw material fuel mixture loading hopper 8: Raw material hopper

9: fuel hopper 10: mixer

11: raw material fuel mixture granulator 12: ignition furnace

13: main exhaust pipe 14: dust collector

15 blower 16: chimney

17: raw material mixture hopper 18: raw material mixture granulator

19: upper light layer 20: raw material fuel mixture layer

21: raw material mixture layer

Iron ore sintering apparatus according to the present invention, the endless rotation of the sintered bogie, the endless wheel for supporting the sintered bogie, a wind box for lowering the air flow of the sintered bogie and positioned below the sintered bogie, and the sintered bogie An upper light filling hopper for charging the upper light into the sintered trolley and forming the upper light layer, and a raw fuel mixture to be loaded on the upper light layer and positioned on the orbit of the sintered trolley. Raw fuel mixture loading hopper for forming a layer, an ignition furnace located on the track of the sinter bogie and the upper portion of the raw fuel mixture layer, and a main exhaust pipe connected to the wind box to force air flow. And a blower installed in the main exhaust pipe to generate air flow, and a small air outlet installed in the main exhaust pipe and flowing along the main exhaust pipe. In a conventional Dwight-roid type sintering machine including a dust collector for removing dust and the like in exhaust gas, a raw material containing no coke between the upper square hopper located on the track of the sintering bogie and the raw fuel mixture hopper. There is provided a raw material mixture loading hopper for charging a mixture into the sintered trolley.

The raw material mixture hopper may be connected to a raw material mixture assembly, and the raw material mixture assembly may be connected to a plurality of raw material hoppers for supplying iron ore, limestone, and the like, and to a mixer for mixing raw materials except for coke.

The raw fuel mixture loading hopper is connected to a raw fuel mixture assembly, which is connected to a plurality of raw material hoppers supplying only iron ore and limestone, and may be connected together to a mixer and fuel hopper mixing raw materials except coke. have.

In addition, the iron ore sintering method having a coke concentration gradient according to the present invention is characterized in that the distribution of coke as fuel in the raw fuel mixture consisting of a mixture containing iron ore, limestone and coke in the sintering machine of the dwarf type It is made to include the raw material fuel mixture in the sintered trolley and sintered so as not to be included in the lower portion.

To this end, the iron ore sintering method includes (A) forming an upper light layer by charging the upper light into the sintering cart; (B) charging the raw material mixture containing essentially no iron ore and limestone on the upper light layer to form a raw material mixture layer; (C) charging a raw material fuel mixture comprising essentially the raw material mixture and the coke on the raw material mixture layer not containing the coke to form a raw material fuel mixture layer; And (d) complexing and sintering the raw fuel mixture layer.

The height of the raw material mixture layer containing no coke is 10 to 30 mm from the upper light layer.

In particular, the coke may be further included in a region within 10 mm of the side wall portion contacting the side wall of the sintering cart of the raw material mixture layer not containing the coke.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Originally, in the sintering industry, as shown in FIG. 1, there is only one raw material fuel mixture hopper 7 by pretreatment, whereas in the present invention, as shown in FIG. 4, not only the conventional raw material fuel mixture hopper 7 but also coke is used. Unused raw material mixture loading hopper 17 is further provided.

Therefore, it is possible to arbitrarily adjust the concentration gradient of coke in the sintering trolley 1 by adjusting the input order and the input amount of the raw material fuel mixture containing coke and the raw material mixture containing no coke.

As shown in FIG. 2, the raw fuel mixture loading hopper 7 includes a plurality of raw material hoppers 8 and a fuel hopper 9 via one mixer 10 and one raw material fuel mixture assembly 11. Since it is impossible to control the concentration gradient of coke as fuel in the sinter bogie 1 because all are connected together, in the present invention, as shown in FIG. 5, the raw material hoppers 8 are all connected to the mixer 10. This results in a raw material mixture in which coke is not contained in the mixer 10.

This mixture, on the one hand, is connected directly to the raw material mixture hopper 17 via the raw material mixture assembly 18, and on the other hand, the raw material fuel mixture assembly 11 together with the coke supplied from the fuel hopper 9 is provided. It is connected to the raw fuel mixture loading hopper 7 by way of it.

Therefore, in the conventional sintering machine as shown in Figs. 1 and 2, as shown in Fig. 6, only charging that can be included coke evenly throughout the upper and lower portions of the sintering bogie 1 is possible. 4 and 5, the raw material mixture loading hopper 17 first loads the raw material mixture without coke as shown in FIG. 7 or 8, and then the raw material fuel mixture hopper. By charging the raw fuel mixture containing coke in (7), charging is possible so that coke is not contained in the central part except the whole lower layer part or the side wall part of the lower layer part of the sintered trolley | bogie 1.

Here, the side wall portion refers to a portion adjacent to the side wall 2 of the sintered trolley 1 as shown in FIG. As described above, the difference in the concentration gradient of coke prevents the generation of contaminants such as sulfur oxides by reducing the calorific value of the lower layer of the sinter bogie 1 by preventing the coke from being distributed in the lower layer of the sinter bogie 1 in the sintering operation. Can be reduced.

In addition, the present invention provides an iron ore sintering method having a concentration gradient of coke by using a sintering machine of the above configuration, which is a raw material consisting of a mixture containing iron ore, limestone and coke in the sintering machine of the Dwight-roid type This method includes forming a raw material fuel mixture layer on the sintering trolley 1 and sintering the coke as fuel in the fuel mixture so that it is not included in the lower layer portion of the sintering trolley 1.

Thus, by reducing the amount of heat in the lower layer of the sintered trolley (1) by charging and sintering the raw fuel mixture having a concentration gradient of coke, it is possible to greatly reduce the generation of contaminants such as sulfur oxides mainly generated during the lower layer sintering. .

The sintering method of the iron ore comprises the steps of: (A) forming an upper light layer 19 by charging the upper light into the sintered trolley (1); (B) charging the raw material mixture including only iron ore and limestone on the upper light layer 19 and not containing coke to form the raw material mixture layer 21; (C) charging the raw material mixture and the raw material fuel mixture including coke on the raw material mixture layer 21 not containing coke to form the raw material fuel mixture layer 20; And (d) complexing and sintering the raw fuel mixture layer 20. That is, by forming a concentration gradient of coke in the lower layer portion of the sintered bogie 1 can reduce the amount of heat in the lower layer portion of the sintered bogie 1 during the sintering operation.

The raw material mixture layer 21 not containing the coke may be formed to have a height of 10 to 30 mm from the upper light layer 19, and preferably may be formed to a height of 20 to 30 mm. In particular, if the coke is further included in a region within 10 mm of the side wall portion contacting the side wall 2 of the sintered trolley 1 of the raw material mixture layer 21 not containing the coke, the quality of the sintered ore does not affect the quality of the sintered ore. It has been found experimentally that pollutants can be reduced.

Hereinafter will be described in detail through specific embodiments of the present invention.

In the present embodiment, before using according to the present invention in a large sintering machine that produces a large amount of sintered ore, the effect of the present invention was confirmed by using a small test apparatus for testing.

Example 1

In order to prove the effect obtained by the present invention, the following experiment was performed using a sintering machine having the configuration as shown in FIGS. 4 and 5. Standard sintered blended raw materials (iron ore blended raw material of powdered iron ore as auxiliary raw material, powdered limestone as secondary raw material and powdered coke as fuel) are prepared through a series of raw material assembly processes. Prepared with a blending ratio of, but in the raw material mixture was mixed with the rest of the raw materials except for the coke, in the raw material fuel mixture was mixed all the raw materials including coke.

Charging to the sintered trolley | bogie 1 charges an upper light first, charges a raw material mixture to a height of 10 mm on it, loads a raw material fuel mixture on it, and sinters it according to a normal sintering method.

Concentrations of sulfur oxides and nitrogen oxides in the sintered flue gas discharged during sintering were analyzed by a commercially available gas analyzer (trade name: Testo 33, Fuel Cell type), and the yield rate and strength of the sintered ore were measured. 2 is shown.

Sintering Experiment Raw Material Blending Plan Raw material kind Compounding ratio (%) ironstone 64.84 Limestone 11.67 Serpentine 1.92 burr 0.45 quicklime 1.12 cokes 3.65 Semi-gloss 16.35

Example 2

The same procedure as in Example 1 was carried out except that the raw material mixture containing no coke was loaded at a height of 20 mm, and the results are shown in Table 2 below.

Example 3

The same procedure as in Example 1 was carried out except that the raw material mixture containing no coke was loaded at a height of 30 mm, and the results are shown in Table 2 below.

Example 4

The same procedure as in Example 1 was carried out except that the raw material mixture containing no coke was loaded at a height of 40 mm, and the results are shown in Table 2 below.

Example 5

The above-described embodiment was loaded with a raw material mixture containing no coke at a height of 30 mm, except that the coke was included within 10 mm of the side wall portion adjacent to the side wall 2 of the sinter bogie 1. It carried out in the same manner as 1, the results are shown in Table 2 below.

Comparative example

The same process as in Example 1 was carried out except that only the raw fuel mixture containing the coke was charged into the sintering cart (1), and the results are shown in Table 2 below.

Test result table Sulfur oxide concentration (ppm) Nitrogen oxide concentration (ppm) Coke ratio (kg / t-s) Recovery rate (%) burglar(%) Example 1 27500 81200 57.49 66.50 72.00 Example 2 23600 80300 56.20 66.20 71.67 Example 3 19200 78900 55.03 65.80 71.45 Example 4 19150 76900 54.37 65.10 70.68 Example 5 20150 79340 55.34 65.55 72.09 Comparative example 35000 83500 58.47 66.70 72.33

As shown in Table 2, when the sintering operation was carried out by applying the present invention in comparison with the comparative example (conventional method), the amount of sulfur oxides and nitrogen oxides decreased sharply until the case of Examples 1 to 3. In the case of Example 4, it can be seen that the decrease was slowed down.

This can reduce the amount of heat in the lower layer by using the raw material mixture layer 21 does not contain coke to reduce the sulfur oxides generated by inhibiting the re-decomposition of calcium sulfate generated by the sulfur absorbent in the sintered bed. In the case of nitrogen oxides, the amount of coke used is continuously reduced.

On the other hand, in the case of sintered ore quality, as the height of the raw material mixture containing no coke in Examples decreases slightly, it can be confirmed that in Example 5, the quality is almost equivalent to that of the conventional method. there was.

That is, the sintering operation can be performed with little effect on the quality of the sintered ore until the height of the raw material mixture containing no coke according to Example 3 is 30 mm by utilizing the heat stored in the lower portion, but the thickness is 40 mm or more. It can be seen that there is an effect on the sintered ore quality.

The reason why the quality of the sintered ore deteriorates is that heat loss occurs in the side wall of the sintered trolley 1. Therefore, as in the case of Example 5, even if the coke is supplied only up to about 10mm from the side wall of the sintered trolley can be confirmed that the degradation of the sintered ore quality can be prevented.

In addition, it was confirmed that by reducing the absolute amount of coke used, the amount of carbon dioxide generated can be significantly reduced.

Therefore, the present invention not only reduces the amount of CO ₂ generated due to the use of a small amount of coke compared to the conventional method, and has little effect on the quality by utilizing the heat calcined to the lower side even when using less coke. In addition, there is an effect that can significantly reduce the generation of pollutants such as sulfur oxides and nitrogen oxides.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (7)

delete delete delete delete Charging the upper light into the sintering cart to form an upper light layer; Charging a raw material mixture consisting of only iron ore and limestone on the upper light layer to form a raw material mixture layer; Charging a raw material fuel mixture including iron ore, limestone and coke on the raw material mixture layer to form a raw material fuel mixture layer; Comprising the step of sintering by complexing the raw material fuel mixture layer, Iron ore sintering method having a concentration gradient of coke, characterized in that the height of the raw material mixture layer is 10 ~ 30mm. delete The method of claim 5, And adding coke to the area of 10 mm from the inner wall of the sintering cart in the raw material mixture layer before forming the raw material fuel mixture layer.