KR101409516B1 - Process for producing sintered ore - Google Patents

Abstract

In this method of producing sintered ores, an iron ore including a high-crystallization iron ore containing crystal water of 4.0 mass% or more as a raw material for sinter, an auxiliary raw material, and a low-temperature combustion solid fuel having a starting temperature of the combustion reaction of less than 450 캜, Solid iron ore containing at least 30% by mass of the high-purity iron ore in the sintering raw material, charging the sintering raw material into a dewrite-lid sintering machine, igniting the surface layer of the sintering raw material, Air is sucked downward from above.

Description

PROCESS FOR PRODUCING SINTERED ORE [0002]

The present invention relates to a method for producing sintered ores for blast furnace raw materials in a steelmaking process.

The present application claims priority based on Japanese Patent Application No. 2009-063466 filed on March 16, 2009, the contents of which are incorporated herein by reference.

A schematic process of a method for producing an sintered ore using a Dwight-Lloyd sintering machine is shown in Fig. As shown in Fig. 1, the sintered ores are produced by sintering the sintering raw material 6 in the sintering machine 30. The sintering raw material 6 is prepared by granulating a mixture of the iron ore 1a as a main raw material, the limestone 2a as an auxiliary raw material, the coke 3a as a solid fuel and the semitransparency 4a, ). The iron ore 1a, the limestone 2a, the coke 3a and the halftone 4a are cut out from the iron ore hopper 1, the limestone hopper 2, the coke hopper 3 and the semi-light hopper 4, respectively, . These cut raw materials are assembled by using a granulator 5 such as a drum mixer while adjusting the humidity such that the water content is about 5.5 to 8.5 mass%. The granulated material is composed of pseudo particles having fine particles of not more than 0.5 mm in particle size attached to the periphery of the core particles of not less than 1 mm in diameter. By using such granules as the sintering raw material 6, the air permeability in the sintering machine can be maintained.

And the sintered raw material 6, which is an assembly, is charged into the surge hopper 7. The sintering raw material 6 is cut out by the drum feeder 8 and charged into the pallet of the sintering machine 30 through the chute 8a to form the filling layer 9. The coke 3a of the surface layer portion of the packed bed 9 is ignited by the ignition furnace 10 and the air is sucked to the lower side of the packed bed 9 by using the fan 20, And the sintering raw material 6 is sintered sequentially from the upper layer toward the lower layer by the heat of combustion of the coke 3a. The sintered cake 11 obtained by the sintering of the sintering raw material 6 is discharged by the light-splitting portion 12 and crushed and sized. The compacted material having a diameter of 5 mm or more after sintering is supplied to the blast furnace as sintered ores. In addition, the sintered ores of 5 mm or less are reused as the semi-light 4a. Also, a part of the sintered ores are reused as sintered ores 46 for the top (flooring).

BACKGROUND ART [0002] Increasing production efficiency of sintered ores as a raw material for a steel mill is required to be backed by the increase in global demand for steel today. At the same time, also in terms of environment, the exhaust gas NOx generated by the combustion of the solid fuel during sintering And the like are strongly required to reduce the emission of air pollutants.

As a conventional technique for improving the productivity of the sintered ores and reducing the air pollutants, for example, Japanese Patent Application Laid-Open Nos. Hei.

Patent Document 1 proposes a method for improving the combustion performance of a solid fuel and improving the productivity of the sintered ores by supplying water vapor generated by spraying on the surface of the sintered light during the sintering reaction to the combustion reaction of the solid fuel in the sintered layer, Quot;

Patent Document 2 proposes a method of improving the combustion efficiency of solid fuel to improve the productivity of sintered ores and to reduce NOx by optimizing the distribution of the water content and the water content in the blended raw materials and supplying water vapor, A method for maximizing a signal is disclosed.

Japanese Patent Publication No. 51-6002 Japanese Patent Publication No. 7-78257

However, the sintering techniques of Patent Document 1 and Patent Document 2 have the following two problems. The first problem is that it is necessary to secure the amount of heat required for evaporation of water. Considering the balance of one row of macroscopically, in the method of spraying on the surface of the sintered layer, it is necessary to supply a latent heat of evaporation corresponding to the number of times of sintering to the sintered layer. In the recent energy saving operation, since the blending ratio of the solid fuel is lowered to the lower limit of the required amount and the sintering is carried out, the margin of the amount of heat in the sintered layer is extremely small. Therefore, when water is sprayed on the sintered layer, it is necessary to separately increase the solid fuel in order to obtain a calorific value corresponding to the quantity of water to be sown.

In the method of mixing steam with the supplied air to the sintered layer to supply water, the latent heat of vaporization is consumed in the plant for producing the steam, so that the amount of heat corresponding to the supplied water amount can not be supplied in consideration of the macro heat balance .

The second problem is that it is inevitable to install large scale spraying facilities on the sintered strands to supply moisture to the sintered layer. The sintering area in a normal sintering machine is 200 to 600 m < 2 >, and in order to improve the combustion reaction of the solid fuel in the entire sintered layer, it is necessary to uniformly distribute the sintering area uniformly over most of the sintered area. For this purpose, it is necessary to regularly provide a plurality of water spray pipes and spray nozzles on the upper part of the sintering machine.

Normally, in the repair of a regular sintering machine, an exchange operation of lifting a sintered pallet after use by a ceiling crane and taking it out to the outside of the sintering machine and bringing the completed sintering pallet in reverse order is carried out routinely. When a large scale watering pipe network and watering device are provided on the strands of the sintering machine, it is necessary to perform a replacement operation of the sintering pallets so as not to interfere with the watering pipe network and the water spraying device, .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described phenomenon, and it is an object of the present invention to provide a method for producing a sintered ores by using a sintering raw material which is supplied with steam in a combustion reaction of a solid fuel, To improve the combustion efficiency of the solid fuel, thereby improving the productivity. It is another object of the present invention to reduce the amount of suction air volume per production amount of sintered ores to reduce the power consumption of the fan and to reduce the total exhaust gas amount and NOx emission amount, And to provide a new sintering technique.

The present inventors have conducted research and development to improve the combustibility of the solid fuel in the sintered layer. Particularly, the inventors of the present invention have conducted various studies in order to simultaneously cause a thermal decomposition reaction of the crystalline water in the iron ores and a combustion reaction of the solid fuel occurring in the sintered layer. As a result, the validity of the sintering method using a combination of solid state iron ores and a solid fuel burned at a relatively low temperature was confirmed.

2 is a schematic view of a vertical section of a sintered layer (filled layer after ignition). This sintered layer is divided into a plurality of zones depending on the progress of the sintering reaction. The sintered layer has the temperature distribution shown in Fig. 2, and the combustion reaction of the solid fuel sequentially proceeds from the upper layer to the lower layer. The sintered layer at any time is divided into a raw material zone (raw material zone) 9a, a drying zone (drying zone) 9b, a sub zone (calcination zone) 9c, ) 9d, and a cooling zone (cooling zone) 9e. The characteristics of each zone are as follows.

The raw material zone 9a is a zone corresponding to a temperature region of less than 100 占 폚. In this raw material zone 9a, the blending raw material (raw material for sinter) charged in the sintering machine is in a wet state.

The drying zone 9b is a zone corresponding to a temperature range of 100 ° C or more and less than 300 ° C. In the drying zone 9b, the drying of the compounding raw material progresses actively.

The calcination zone 9c is a zone corresponding to a temperature range of 300 deg. C or more and less than 700 deg. In this calcination zone 9c, the decomposition of crystal water in iron ore and the reaction of decarboxylic acid in limestone occur.

The combustion zone 9d is a zone corresponding to a temperature range of 700 ° C or higher and lower than 1300 ° C. In the combustion zone 9d, the solid fuel reacts with oxygen in the suction air and is burned, and the melting reaction of the iron ore and the subsidiary raw material and the liquid phase sintering proceed simultaneously.

The cooling zone 9e is a zone corresponding to a temperature range from 1300 DEG C to room temperature. In this cooling zone 9e, a series of sintering reactions are completed, and the resulting sintered body (sintered cake) is cooled.

Powdered coke and anthracite, which are widely used as solid fuels for general sintering, start the combustion reaction in the combustion zone 9d reaching a temperature of 700 占 폚 or higher. On the other hand, the number of crystals contained in the iron ore releases water vapor by pyrolysis in the calcination zone 9c whose temperature is lower than that of the combustion zone 9d.

The inventors of the present invention have found that by using combustion solid fuel having a low combustion start temperature which is burned in the calcination zone 9c, water vapor generated by pyrolysis of crystal water in iron ore can be effectively utilized for improving the combustibility of solid fuel .

More specifically, as a result of sintering test using a raw material (sintering raw material) obtained by mixing a combustion solid fuel having a low combustion start temperature and a high-crystallization iron ore, the present inventors have found that the thermal decomposition reaction of the crystalline water and the combustion Are simultaneously generated in the calcining zone 9c, and it is possible to effectively supply water vapor to the combustion atmosphere of the solid fuel. The present inventors have also found that by using a combustion solid fuel having a low combustion start temperature (low-temperature combustion solid fuel), the reaction between H ₂ O and C is promoted to improve the productivity and reduce NOx in the exhaust gas by combustion Respectively.

The present invention has been made on the basis of the above knowledge and employs the following means.

(1) In the method for producing an sintered ore according to the present invention, iron ore containing a high-crystallization iron ore containing crystal water of 4.0 mass% or more as a raw material for sintering, an auxiliary raw material, and a low temperature combustion solid A solid fuel containing 10 mass% or more of fuel is blended so that the above-mentioned high-quality purified iron ores are contained in the sintering raw material in an amount of 30 mass% or more, the raw material for sinter is charged into a dwite-type sintering machine, , Air is sucked downward from above the sintering raw material.

(2) In the method of producing the sintered ores according to (1), the low-temperature combustion solid fuel is a char obtained by carbonizing any one of bituminous coal, lignite or mixed coal obtained by mixing bituminous coal and lignite, .

According to the present invention, it is possible to provide a raw material for sinter in which water vapor is supplied to the combustion reaction of a solid fuel, without using water spray and water vapor addition, which are conventionally used in the production of sintered ores as raw materials for blast furnace charging in a steelmaking process . Further, by using this sintering raw material, it is possible to improve the productivity of the sintered ores and to reduce NOx in the exhaust gas.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a process drawing showing a schematic process of a method for producing sintered ores;
2 is a schematic view of a section in the vertical direction of the sintered layer.

Specific methods of the present invention will be described below. In the method for producing sintered ores by using the above-described Dewit-Lloyd sintering machine, a low-temperature combustion solid fuel having a combustion start temperature of less than 450 占 폚 is used as the solid fuel to be mixed with the raw material for sinter.

As this low-temperature combustion solid fuel, a coal (carbonaceous material) obtained by carbonizing a mixed coal obtained by mixing bituminous coal, lignite, or bituminous coal and lignite at a relatively low temperature of about 800 ° C can be used. These cars start to burn in the low temperature region of 330 to 450 占 폚 and reach the maximum combustion state (maximum weight decrease temperature) in the temperature range of 530 to 550 占 폚. The difference in combustion temperatures can be sufficiently combusted in the calcination zone 9c. At the same time, in the calcination zone 9c, the supply effect of water vapor generated from the crystal water in the iron ore can be obtained.

On the other hand, when ordinary powder coke and anthracite coal are used as the solid fuel, the maximum weight reduction temperature of the powdered coke and the anthracite coal is as high as 700 to 800 DEG C, so the combustion amount in the calcination zone 9c is extremely partial. As a result, a combustion reaction occurs mainly in the combustion zone 9d in which no steam is supplied. In such a burning condition, even if the high-purity iron ore is blended to some extent, the expected effect of steam supply can not be obtained. Here, the ordinary powder coke is a powdery coke obtained by pulverizing powdery coke or coke produced in the process of producing the blast furnace coke and in the process of conveying to the blast furnace. As the coking coke, coking coal and non-coking coking coal (non-caking coking coal) are used.

Table 1 shows the combustion performance of the low-temperature combustion solid fuel and the conventional solid fuel. The combustion start temperature and the maximum weight reduction temperature in Table 1 were measured using a differential thermal analysis apparatus.

The solid fuel used in the method for producing the sintered ores according to the present invention may contain only a low-temperature combustion solid fuel. The solid fuel may also include a solid fuel other than the low temperature combustion solid fuel and the low temperature combustion solid fuel (e.g., powdered coke, anthracite coal, and carbon containing dust, etc.). The low-temperature combustion solid fuel may be a sub-bituminous coal, a lignite, or a car obtained by carburizing one of mixed coal obtained by mixing bituminous coal and lignite (low-temperature combustion car). When only this low temperature combustion car is used as the solid fuel, the combustion effect of the solid fuel can be maximized. Preferably, as the solid fuel, the whole amount of the car which is subcrystallized at 800 ° C is used. As shown in Table 1, the combustion start temperature and the maximum weight decrease temperature of the tea (sub-bituminous coal car) obtained by carburizing sub-bituminous coal at 800 ° C were 530 ° C and 330 ° C, respectively. Therefore, the tea obtained from the sub-bituminous coal can be burned at a lower temperature than the low-temperature combustion solid fuel. However, even in the case of using sub-bituminous coal, the sub-bituminous coal high-temperature carbonized car under high temperature conditions exceeding 1000 deg. For example, as shown in Table 1, the combustion start temperature of the sub-bituminous high-temperature coal gas stream which is carbonized at 1100 ° C is 540 ° C. Therefore, when a sub-bituminous high-temperature car is used, the combustibility of the solid fuel can not be improved. Therefore, even in the case of using sub-bituminous coal, it is preferable to use a car which is carbonized at 1000 ° C or lower.

Furthermore, by using a solid fuel obtained by mixing a solid fuel other than the low-temperature combustion solid fuel with the low-temperature combustion solid fuel, the carbonaceous material-containing powder produced in the coke process or inside and outside the steelmaking plant can be utilized as a solid fuel. However, the mixing ratio of the low-temperature combustion solid fuel to the total solid fuel should be 10 mass% or more. By including not less than 10% by mass of the low-temperature combustion solid fuel, the combustibility of the solid fuel can be sufficiently improved.

Next, mixing conditions of the high-purity iron ores will be described. Iron ore containing 4.0% by mass or more of crystal water is used as the high-purity iron ore. In the iron ores having an amount of crystalline water of less than 4.0 mass%, the dehydration reaction is completed in the early stage of the calcination zone 9c, so that the steam is not sufficiently supplied to the combustion reaction of the solid fuel. It is necessary to use a high-quality constant iron ore containing not less than 4.0 mass% of crystal water in order to continuously supply water vapor to the temperature region where combustion of the solid fuel occurs. Further, it is not necessary for the high-purity iron ore used in the sintering raw material to carry out preliminary treatment for removing water before mixing.

A high-crystallizing iron ore containing 4.0 mass% or more of crystal water, characterized in that it comprises a fullerite ore containing 7 to 9 mass% of crystal water, a maramba ore containing 4 to 8 mass% of crystal water and 4 to 6 mass% It is preferable to use a brookman ore containing crystal water. All of these high-purity iron ores contain mineral phases of iron hydroxide. In addition, for example, a scale containing iron carbonate and goethite containing crystal water of 4.0 mass% or more can also be used as a raw material for sintered ores. Further, as shown in Table 2, a plurality of high-purity iron ores may be mixed and used.

Further, it is more preferable to use a pysolite ore having a crystal water content of 8.0% by mass or more (for example, Yandiczuna in Table 2). This pysolite ore (Yandikugina) has the largest content of crystalline water in the iron ore market currently available on the market. The upper limit of the content of the crystal water of the high-purity iron ore is not particularly limited. However, since the crystal number is water combined with the compound in the iron ore, the content of the crystal water of the high-purity iron ore does not include 100 mass%.

The mixing ratio of the high-purity iron ore needs to be 30% by mass or more in the entire raw material for sinter. When the mixing ratio of the high-purity iron ore in the sintering raw material is less than 30 mass%, a sufficient amount of water vapor can not be supplied to the calcination zone 9c. That is, the water vapor generated by the decomposition of the crystal water is discharged as exhaust gas accompanied by the sequential aspiration gas. Therefore, when the amount of generated water vapor is small, the concentration of water vapor in the calcination zone 9c is lowered.

On the other hand, the rate of reaction between carbon and water vapor on the surface of solid fuel greatly depends on the concentration of water vapor in the atmosphere. Therefore, in order to obtain sufficient effect by water vapor, it is necessary to increase the water vapor concentration. According to the investigations of the present inventors, in order to obtain a sufficient reaction rate of carbon and water vapor, the mixing ratio of the high-purity iron ores in the sintering raw material should be 30 mass% or more. In consideration of the combination of the auxiliary raw material and the solid fuel, the mixing ratio of the high-purity iron ores in the raw materials for sinter is preferably 80 mass% or less.

Preferably, the pulp orite ore having a crystal water content of 8.0% by mass or more is contained in the total sintering raw material in an amount of 35% by mass or more and 45% by mass or less. In this case, a sufficient amount of water vapor can be secured in the calcination zone 9c of the sintered layer. In the calcination zone 9c, water vapor is constantly supplied from the high-purity iron ores by the heat supplied from the low-temperature combustion solid fuel. This supply of water vapor promotes the water gas reaction (reaction of water vapor with carbon) and the water gas shift reaction (reaction of water vapor and carbon monoxide) to supply hydrogen. As a result, the heat transfer rate in the calcination zone 9c is improved, and the productivity of the sintered ores is increased. Further, hydrogen can reduce NOx, and the amount of NOx generated can be suppressed. In addition, the combustion efficiency of the solid fuel is improved by the water gas shift reaction. Further, in order to improve the heat transfer rate in the calcination zone 9c and increase the productivity (sintering speed) of the sintered ores, there is no need to consider generation of an excessive melt (melt). The inventors of the present invention have confirmed that by using a low-temperature combustion solid fuel and a high-purity iron ore, sintered ores can be produced without generating excessive melt.

Specifically, for example, in the sintering process shown in Fig. 1, an iron ore containing a high-crystallization iron ore containing crystal water of 4.0 mass% or more, an auxiliary raw material, and a low temperature combustion A solid fuel containing 10% by mass or more of solid fuel is blended so as to contain 30% by mass or more of cementitious iron ore and used as a raw material for sintering. This raw material for sinter is charged into a Dwight-Lloyd type sintering machine and is ignited at the surface layer of the raw material for sinter. Air is sucked from the upper side (cooling zone 9e) of the sintered layer (sintering raw material) in this sintering unit toward the lower side (raw material zone 9a). The sintering reaction proceeds continuously by the suction of the air to produce sintered ores.

According to the above-described method, the combustibility of the solid fuel can be remarkably improved, and the productivity of the sintered ores can be improved. Further, the NOx concentration in the exhaust gas can be significantly reduced.

Example

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

Sintered light was experimentally prepared from a predetermined blend material (raw material for sinter) using a sintering tester having a diameter of 30 cm and a layer height of 60 cm. After the compounding material was charged to a height of 60 cm in the sintering test apparatus, a propane gas burner was spun into the solid fuel at the surface layer of the packed bed for 90 seconds and ignited. Thereafter, sintering reaction was performed while sucking air downward at a constant negative pressure of 15 kPa. After completing a series of sintering reactions, the sintered body was sufficiently cooled and crushed by falling four times from a height of 2 m to recover sintered ores having a particle size of 5 mm or more. The production rate and yield of the sintered ores were calculated from the material balance of the sintered ores and the blended materials. Similarly, the frame front speed (FFS) indicating the sintering speed was also calculated. Further, the oxygen concentration and the NOx concentration in the exhaust gas were measured.

The mixing conditions of the raw materials for sinter and the test results of the raw materials for sinter are shown in Tables 2 and 3, respectively. The solid fuels in Table 2 correspond to the solid fuels in Table 1, respectively.

As shown in Table 2, the iron ores including the high-crystallization iron ore containing the crystal water of 4.0 mass% or more as the blending raw materials of the first, second and third to fifth reference examples and the iron ores containing the high- A solid fuel containing 10% by mass or more of a low-temperature solid fuel having a temperature of less than 450 ° C (for example, the difference in Table 2) was used. Iron ore was blended in the blending raw materials (sintering raw materials) of the first, second and third to fifth reference examples so that the high-purity iron ores were contained in an amount of 30 mass% or more. As a result, as shown in Table 3, the sintering speed (FFS) was improved without lowering the yield of the sintered ores and the production rate could be greatly increased. Further, in the first, second and third to fifth reference examples, the combustion performance of the solid fuel was also greatly improved, and the oxygen concentration (excess air ratio) and the amount of NOx generation in the exhaust gas were lowered.

On the other hand, low-temperature combustion solid fuels were not used for the blending materials of the first, second and sixth comparative examples. For the blending raw materials of Comparative Example 3, no high-purity iron ore was used. In addition, 30% by mass or more of high-purity iron ore was not contained in the blending raw material (sintering raw material) of Comparative Example 4. In the solid fuel of the blended material of Comparative Example 5, 10% by mass or more of low-temperature combustion solid fuel was not added. Further, as a solid fuel, a sub-bituminous high-temperature carbonized tea having a high combustion initiation temperature was blended into the blended material of the sixth comparative example. In the first to sixth comparative examples, the production rate and the FFS decreased and the combustibility of the solid fuel decreased, and the oxygen concentration (excess air ratio) and the NOx generation amount in the exhaust gas increased.

It is possible to provide a method for producing an sintered oresignal that significantly improves the combustibility of the solid fuel and improves the productivity of the sintered ores and significantly reduces the NOx concentration in the exhaust gas.

1: Iron ore hopper
1a: iron ore
2: Limestone Hopper
2a: limestone
3: Coke Hopper
3a: Coke
4: Half light hopper
4a: Halo
5: Assembly machine
6: Sintered raw material
7: Surge hopper
8: Drum feeder
8a: Suit
9: filling layer (sintered layer)
9a: raw material stand (raw material zone)
9b: drying zone (drying zone)
9c: Small scale (calcination zone)
9d: Combustion zone (combustion zone)
9e: Cooling zone (cooling zone)
10: With ignition
11: Sintered cake
12:
20: Aerator
30: Sintering machine
46: Sintered ores for upper part

Claims (2)

A method for producing a sintering raw material, comprising the steps of: mixing an iron ore containing a high-crystallization iron ore containing 4.0 mass% or more of crystal water, a sub-raw material, a solid fuel including a semi-light and a car having a start temperature of a combustion reaction of less than 450 deg. Wherein the mixing ratio of the car is 10 mass% or more with respect to the total solid fuel, the mixing ratio of the high-crystallization iron ore is 35 mass% or more with respect to the whole sintered raw material,
The raw material for sinter is charged into a Dwight-type sintering machine,
The surface layer portion of the raw material for sinter is ignited,
Wherein air is sucked downward from above the sintering raw material. The method according to claim 1, wherein the tea is obtained by carburizing any one of bituminous coal, lignite, or mixed coal obtained by mixing the bituminous coal and the lignite.

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