JPH0734141A - Production of sintered ore - Google Patents

Abstract

PURPOSE:To decrease fuel for ignition and to improve a a combustion rate by adding specific iron ore to a specific position and heating the surface layer part of raw materials by microwaves in a preheating method by hot air using a Dwight-Lloyd sintering machine. CONSTITUTION:The iron ore contg. >=0.3% Fe3O4 is added at 5 to 50wt.% onto the layer within 50mm from the front surface of the raw material layer 7 at the time of charging the compounded raw materials 1 onto a pallet 6. While the hot air is blown to the surface layer of the raw materials between a raw material charger 5 and an ignition furnace 17 by a hot air supplying device 15, the air is sucked from the lower side to dry and preheat the surface layer of the raw materials. The surface layer part is then heated up by the microwaves supplied from a microwave generator 16, the surface layer part is ignited and sintered by an ignition furnace 17. The magnetite and carbonaceous solid fuel interposed between the raw material particles of the surface layer dried and preheated by the hot air are selectively heated by the microwaves according to this method. In addition, the magnetite is oxidized to generate heat while the magnetite is heated up and, therefore, the magnetite functions as a heating medium for the raw materials and is capable of heating the ambient raw materials as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an improved method for producing sinter ore by a Dwightroid sinter, and more specifically, a method for producing sinter ore by preheating a sinter ore raw material and raising the temperature to sinter. It is about.

[0002]

2. Description of the Related Art Generally, a Dwightroid type sintering machine is widely used for the sintering of iron ore. In this type of sintering machine, after igniting the surface layer of the blended raw material in the ignition furnace, the combustion zone in the raw material layer gradually shifts from the surface layer portion to the lower layer portion by inhaling downward, and the total sintering is completed. The process is 15-2
It will be completed in about 0 minutes.

The optimum operation in the production of sinter ore is to maintain the quality of the sinter ore obtained, to maximize the production rate, and to minimize the fuel consumption rate and ignition fuel consumption rate. Aims to reduce the amount of coke, anthracite, etc. added as fuel within the range of maintaining the quality of sinter, and the coke oven gas and pulverized coal which are ignition fuels. However, even if the blending ratio of the fuel or the amount of the ignition fuel is unnecessarily reduced, no good result can be obtained, and if it is drastically reduced, the quality of the sinter ore is deteriorated, and the amount of returned ore is increased. However, the fuel consumption rate and the ignition fuel consumption rate deteriorate.

As a method for solving the above-mentioned problems of the sintered ore manufacturing method, for example, Japanese Patent Publication No. 54-24682 discloses a dwightroid type sintering machine in which a raw material is supplied to a pallet. A hot air supply device is installed between the ignition furnaces, hot air is blown from the hot air supply device to the upper surface of the raw material, only the upper layer portion of the raw material is heated to a high temperature, and the upper layer portion of the raw material that has reached this high temperature is sequentially ignited. There is described a method for producing a sinter, which comprises sintering while alleviating the thermal shock of.

Further, Japanese Patent Publication No. 57-45296 discloses a sintering machine in which raw materials are layered and ignited from the upper surface for sintering, and a hot air supply device is provided between a ore feeder and an ignition furnace. The hot air is blown onto the upper surface of the raw material to inhale it from below, only the upper layer of the raw material is dried, and then ignited in an ignition furnace, and a hot air supply device is installed after the ignition furnace to blow hot air from here and perform the sintering reaction while inhaling from below. A method for producing a sintered ore characterized by squeezing is described.

[0006]

In the above preheated sintering method using hot air, ignition is performed by mitigating the thermal shock of the surface layer of the raw material in the ignition furnace and by reducing the relative moisture condensation zone by expanding the drying zone. The suction amount of the subsequent combustion air is increased and the sintering time is shortened. Also, since the maximum temperature of the heat pattern of the surface layer of the preheated raw material layer is higher than that when it is not preheated, the production rate, product yield, sinter quality are improved, and the fuel consumption rate and ignition fuel consumption rate are also reduced. To do. However, it is not preheated above the hot air temperature, and is close to the maximum temperature of the exhaust gas from the sintering machine or cooler exhaust gas, which is the hot air source.
Even if hot air near 0 ° C. was blown, the preheating temperature of the surface layer of the raw material was limited to, for example, about 300 to 350 ° C. even at the highest temperature.

The sintering method using the Dwightroid type sintering machine is as follows.
Since air is sucked in from above through to the bottom through the raw material layer, the sintering temperature of the raw material surface layer is lower than that of other parts due to aeration, and there is a problem that the quality of the sintered ore in the upper layer tends to deteriorate. Therefore, it was desired to keep the temperature higher.

If the fuel in the surface layer of the raw material can be concentrated in advance to a temperature in the vicinity of the ignition temperature, the ignition operation will be relaxed by the large heat input, so that the fuel such as coke oven gas used at the time of ignition will be used. Can be reduced. In addition, since the fuel in the surface raw material is ignited and burned rapidly, the concentrated heat generation effect gradually spreads to the combustion of the fuel in the raw material of the lower layer, which greatly increases the burning speed of the fuel such as coke dust and anthracite. As a result, the maximum temperature in all layers is increased, and the yield of sintered products is improved, the fuel consumption rate is reduced, and the NOx generation amount is reduced.

[0009]

SUMMARY OF THE INVENTION The present invention is a sintering process in which hot air is blown from the upper surface of a raw material charged in a sintering pallet and sucked downward to preheat the surface layer of the raw material and then ignite and sinter. In the ore manufacturing method, 50 mm from the upper surface of the raw material when charging the raw material
5 layers of iron ore powder containing 0.3% or more of Fe ₃ O ₄ in the layers within
˜50 wt% is added, and between the raw material charging position and the ignition position, first, hot air is blown to the surface of the raw material layer to inhale from below to dry and preheat the surface layer portion, and then the surface layer portion is heated by microwave. It is a method for producing a sinter that is characterized in that after the temperature is raised, it is ignited in an ignition furnace and sintered. When charging the above raw material, the raw material is Fe ₃ O having a particle size of 0.5 mm or less.
Add iron ore powder containing 0.3% or more of ₄ to the surface layer part by rolling classification of the raw material at the time of charging the raw material, and at the time of charging the raw material, 0.3% or more of Fe ₃ O ₄ It is preferable that the raw material mixed with the iron ore powder containing is charged into the surface layer portion by two-step charging.

[0010]

The function of the present invention is 50 mm from the upper surface of the raw material when charging the raw material.
At least 5 to 50% by weight of iron ore powder containing 0.3% or more of Fe ₃ O ₄ is added to the layers below, and first, while blowing hot air to the surface of the raw material layer between the raw material charging position and the ignition position, downward. The raw material surface layer is inhaled by dry preheating, and then the surface layer portion is heated and heated by the microwave and then ignited and sintered in an ignition furnace, so that first, between the raw material particles of the surface layer portion which is dry preheated by hot air. The intervening magnetite and carbonaceous solid fuel, such as coke or anthracite, are selectively heated by the irradiated microwaves, and since the magnetite heats up by oxidation while being heated, it functions as a heat-raising medium for the raw material, and Can also be heated, and the temperature can be efficiently raised by heating.

Further, since the temperature of the heated surface layer portion, particularly the carbonaceous solid fuel interposed in the surface layer, has been raised to almost the ignition temperature, the solid carbon material in the surface layer can be quickly ignited by the subsequent ignition operation. Therefore, the length of the ignition zone can be shortened, and excess ignition fuel can be reduced.

When charging the above raw material, the raw material has a particle size of 0.
If iron ore powder containing 0.3% or more of Fe ₃ O ₄ of 5 mm or less is blended, a classification / sieving means, such as a slit bar or a bar-shaped screen, arranged at the chute part of the raw material charging or the tip part of the chute. Iron ore powder containing fine particles of Fe ₃ O ₄ by rolling classification is 50 mm from the surface
It can be dispersed and charged into the layers within. As a result, the microwave entering from the surface of the raw material layer raises the temperature of magnetite and carbonaceous solid fuel.

When charging the above raw materials, Fe ₃ O ₄
A raw material containing a predetermined amount of iron ore powder containing 0.3% or more of the above is classified as a normal raw material and charged using separate charging devices, or the above Fe ₃ O ₄ mixed raw material is heated with hot air for preheating. By carrying out two-stage charging such as transfer charging, the amount of magnetite as a heating medium can be appropriately controlled, and the temperature rising temperature can be controlled accurately. A predetermined amount of carbonaceous solid fuel can be blended in this two-stage charging.

The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a vertical sectional explanatory view showing an outline of an example of an apparatus for carrying out the present invention.

As shown in the figure, in the normal sintering operation, the sintering compound material 1 is continuously supplied from the surge hopper 2 through the drum feeder 3 and the charging device 5 onto the pallet 6 to form the material layer 7. Form. Sprocket 4 on the raw material supply side
While rotating the pallet 6 at a low speed,
When the intake blower 13 sucks air from a plurality of windboxes 8 provided on the lower side through the main duct 9 and the exhaust gas dust collector 12, and the surface of the raw material layer 7 is ignited in the ignition furnace 17, the raw material layer 7 on the pallet 6 is discharged. The sintering reaction is completed over all layers while reaching the part.

Exhaust gas discharged from the sintering step is used for the operation of preheating and sintering the raw material layer 7 charged in the pallet 6 with hot air. Specifically, the hot air discharged from the exhaust tube 21 of the sinter cooler 20 or the exhaust gas discharged from the wind box 8 having a temperature equal to or higher than a predetermined temperature is adjusted by the exhaust gas discharge pipe 10 to the flow rate adjusting valve 11 and the exhaust gas dust collector 12 '. ,
The hot air obtained via the suction blower 13 'can be used. The cooler exhaust gas and the sintering exhaust gas of the sinter are controlled individually or in combination to introduce hot air of 200 to 400 ° C. into the hot air supply device 15, and the raw material layer 7 of the raw material layer 7 is supplied before entering the ignition furnace 17. Blowing hot air on the surface, 1-3 from below
If suction is performed for a minute to dry and preheat the upper part of the charge, the maximum temperature can be raised to 300 to 350 ° C.

When the temperature of the hot air is 200 ° C. or lower, a sufficient preheating effect cannot be obtained, which is not preferable. On the contrary, when trying to obtain hot air having a hot air temperature of 400 ° C. or higher, for example, the problem that the productivity of the sinter cooler 20 is reduced occurs, and the hot air is placed in the middle of a conduit for introducing such high-heat gas. This is not preferable in terms of equipment because it significantly shortens the life of the blower. Further, as shown in FIG. 2, when the hot air suction time is less than 1 minute, the improvement effect is small, and when the hot air suction time is 3 minutes or more, the effect of shortening the sintering time reaches a peak, and thus an effect commensurate with the extension of the preheating time is obtained. In other words, the result is that the productivity is decreased.

According to the present invention, when charging the raw material into the pallet 6, the Fe ₃ O ₄ layer is formed within 50 mm from the surface layer of the raw material layer 7.
5 to 50% by weight of iron ore powder containing 0.3% or more is added. The magnetite powder dispersed and mixed in the surface layer portion of the raw material layer 7 does not cause any problem even if it is dispersed in a small amount in a region exceeding 50 mm from the surface layer, but since the microwave to be irradiated enters through the gaps between the raw material particles, it enters. Naturally, there is a limit to the depth of penetration, and the function as a heating medium cannot be expected unless the microwave reaches. As a microwave with which the surface layer portion of the raw material layer 7 is irradiated, a microwave having a frequency band of 915 MHz and 2450 MHz can be used, and the output may be 25 kW per 0.5 t raw material. The required output can be obtained by arranging a plurality of microwave generators in parallel.

The iron ore powder containing Fe ₃ O _{4 in an amount} of 0.3% or more is more preferable as the proportion of magnetite is larger. If the iron ore powder contains less than 0.3% of magnetite,
The compounding amount of the heating medium for increasing the temperature to a desired temperature is increased within a limited layer within 50 mm from the surface layer of the raw material layer 7. For example, when the magnetite powder is compounded and charged, if the magnetite powder is fine particles of 0.5 mm or less, it can be interposed in the surface layer portion of the raw material layer 7 by rolling classification at the time of charging. In addition, as the temperature of the magnetite powder is increased by microwaves, the finer the particles, the larger the surface area of the magnetite powder and the skin effect. When a large amount of fine iron ore powder having a low proportion of magnetite is used, it is densely dispersed in the surface layer of the raw material layer 7, so that the microwave temperature rises sequentially from the surface magnetite powder.
It is not preferable because the hematite fine particles generated by the heat of oxidation during the temperature rise serve as a barrier to easily prevent the microwave from entering the raw material layer 7.

The amount of Fe ₃ O ₄ containing iron ore powder is 5 to 5
An iron ore powder with a high proportion of magnetite is preferable because it can be added in an amount of 0% by weight because the amount of the iron ore powder mixed as a heating medium can be reduced. However, if it is less than 5% by weight, it becomes difficult to raise the surface layer portion of the raw material layer to the maximum temperature or higher by hot air preheating. On the contrary, when it exceeds 50% by weight, the magnetite powder is densely dispersed in the surface layer of the raw material layer 7 as described above,
The fine hematite particles generated by the heat of oxidation during temperature rise serve as a barrier to prevent microwaves from entering the raw material layer 7.

Examples of Fe ₃ O ₄ -containing iron ore brands include Carol, Lobe River, Donimaray, Bairadila, Kudremuk and the like. Further, as a substitute for Fe ₃ O ₄ -containing iron ore, a scale containing a Fe ₃ O ₄ composition can be used. The Fe ₃ O ₄ content in the iron ore of the above brand varies from several% to several tens% respectively, but by appropriately selecting and compounding these, the dispersion amount of magnetite can be reduced to 5 to 50% by weight. Can be adjusted.

As a means for charging Fe ₃ O ₄ -containing iron ore powder into a layer within 50 mm from the surface layer of the raw material layer 7, as shown in FIG. 1, Fe ₃ O ₄ stored in the raw material hopper 18 is used.
A raw material containing a predetermined amount of contained iron ore powder and coke serving as a fuel is connected to the middle of the pipe of the hot air supply device 15 via the raw material blowing device 19, and is sprayed on the surface layer of the raw material layer 7 of the pallet 6 with hot air to produce Fe ₃ O. ₄ a method of forming a containing raw material layer,
Alternatively, Fe ₃ O may be provided between the hot air supply device 15 and the charging device 5.
A two-stage charging method, such as a method of installing and charging a dedicated charging device 14 for a raw material containing _4- containing iron ore powder and coke, a charging device 5 including a sloping chute, or a charging device not shown. A classification / sieving means such as a slit bar or a rod-shaped screen is arranged at the tip of No. 5, and fine particles of Fe ₃ O ₄ -containing iron ore powder are charged into the surface layer of the raw material layer 7 by this classification / sieving action. The method can be adopted.

A hot air supply device 15 and a microwave generator 16 are installed between the charging device 5 and the ignition furnace 17. First, the surface layer portion of the raw material layer 7 is dried and preheated by the supplied hot air, then heated and heated by the microwave supplied from the microwave generator 16, and then ignited in the ignition furnace 17 to produce a sintered ore. According to the present invention, before entering the ignition furnace 17, the compounded raw material of the fuel such as Fe ₃ O ₄ -containing iron ore powder or coke in the surface layer portion of the raw material layer 7 is combined with the hot air for preheating for drying and the heating for raising temperature by microwave. The temperature can be raised to about 600 ° C. If the heating temperature by the microwave is 600 ° C. or more, the heating is excessive and the problem of ventilation failure due to destruction of the granulated sintering raw material occurs, which is not preferable.

As described above, since the temperature of the surface layer of the raw material layer can be raised and the temperature of the fuel such as powdered coke and anthracite can be raised to near the ignition temperature, the maximum temperature of the surface layer of the charged material after ignition is significantly increased. However, since the effect is sequentially propagated to the lower layer, the product yield of the upper layer of the charge and the quality of the sinter are greatly improved, the fuel and ignition fuel in the blended raw materials are greatly reduced, and the NOx generation amount is increased. Can be achieved at the same time.

[0026]

[Examples] Table 1 shows blended raw materials used in this experiment. The raw materials to be blended are various iron ore and limestone, quicklime, serpentine, scale and other miscellaneous raw materials adjusted so that SiO ₂ and Al ₂ O ₃ in the sintered ore are 5.8% and 1.8%, respectively. The basicity was 1.7. Return mineral content is 15%
The coke blending ratio was kept constant at 3.8%.

[0027]

[Table 1]

After blending returned ore and powder coke into the blended raw material, added water was added, and the mixture was mixed and granulated by a mixer, and an experiment was conducted in a 40 kg test pot at a layer thickness of 400 mm and a negative pressure of 1200 mmAq constant. In Example 1, the lobe river ore containing 0.4% of Fe ₃ O ₄ was blended so as to be 30% by weight, the ignition time was 1.5 minutes, and hot air at 300 ° C. was sucked for 2.0 minutes before ignition. , 25 kW from 1.5 minutes after the latter half of the time
Of microwave for 0.5 minutes, 25m from the surface of raw material
The temperature was raised to 400 ° C. at the m position.

In Example 2, the lobe river ore containing 0.4% of Fe ₃ O ₄ was blended so as to be 30% by weight within 50 mm of the surface layer portion of the blended raw material as the charge, and the mixture was mixed before ignition to 3%.
Suction hot air at 00 ° C for 2.0 minutes, and after 1.5 minutes in the latter half of that time, a microwave of 25 kW was fed to the upper layer of the raw material 25 m.
After irradiating at 500 ° C. at m position, ignition was performed for 1.5 minutes. The powder coke content was set to be the same as in Example 1.

Comparative Example 1 is a conventional method in which drying / preheating before ignition is not performed. Comparative Example 2 is a preheating sintering method in which only drying and preheating before ignition are performed, and 400 at a position 25 mm from the upper layer of the charging material.
The temperature was raised to ° C.

FIG. 3 shows the production rate of the pot test, the sintering time, the product yield, the powder coke basic unit, the ignition coke oven gas basic unit, and TI obtained in Comparative Examples 1 and 2 and Examples 1 and 2. Low temperature reduction powdering index (RDI) and NOx emission intensity are shown. In the method of the present invention, the maximum temperature of the in-layer heat pattern is increased.
The production rate of the method of the present invention is the same as that of the conventional preheating sintering method, the product yield is significantly improved, the coke consumption rate and the coke oven gas consumption rate for ignition are significantly reduced, and the TI and RDI are improved. , NOx emission intensity was also significantly reduced. It is possible to freely change the contents of combination of hot air temperature, hot air suction time, microwave power and heating temperature rising time within the range described above depending on the operation orientation, and this degree of freedom is also an advantage of the method of the present invention. Is.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing an example of an apparatus for carrying out the present invention.

FIG. 2 is a diagram illustrating a relationship between a dry preheating time and a sintering time.

FIG. 3 is a diagram showing results of pot tests of the method of the present invention and the conventional method.

[Explanation of symbols]

 1 Sintered compound raw material 2 Surge hopper 3 Drum feeder 4 Sprocket 5 Charging device 6 Pallet 7 Raw material layer 8 Windbox 9 Main duct 10 Exhaust gas discharge pipe 11 Flow rate control valve 12 Exhaust gas dust collector 12 'Exhaust gas dust collector 13 Suction blower 13' Suction blower 14 dedicated charging device 15 hot air supply device 16 microwave generator 17 ignition furnace 18 raw material hopper 19 raw material blowing device 20 cooler 21 exhaust stack

Front Page Continuation (72) Inventor Haruhisa Suzuki 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Nagoya Steel Works (72) Inventor Yozo Hosoya 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Stock Company Technology Development Division

Claims (3)

[Claims] 1. A sinter ore manufacturing method in which hot air is blown from the upper surface of a raw material charged in a sintering pallet and sucked downward to preheat the surface layer of the raw material and then ignite and sinter the raw material charging. At times, 5 to 50% by weight of iron ore powder containing 0.3% or more of Fe ₃ O ₄ is added to a layer within 50 mm from the upper surface of the raw material, and hot air is first blown to the surface of the raw material layer between the raw material charging position and the ignition position. A method for producing a sintered ore, which comprises sucking air from below while spraying to preheat the surface layer portion to dryness, and then heating and heating the surface layer portion by microwaves and then igniting and sintering in an ignition furnace. 2. When charging the raw material, an iron ore powder containing 0.3% or more of Fe ₃ O ₄ having a particle size of 0.5 mm or less is blended in the raw material, and the surface layer is formed by rolling classification of the raw material during charging the raw material. The method for producing a sinter according to claim 1, wherein the sinter ore is charged into the part. 3. The charging of the raw material, the raw material mixed with iron ore powder containing 0.3% or more of Fe ₃ O ₄ is charged into the surface layer portion by two-step charging. Sintered ore manufacturing method.