JP2012026016A - Method of manufacturing sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a sintered ore which can improve a product yield of the sintered ore without causing the lowering or the like of the rigidity of the sintered core at an upper layer of the sintered ore.SOLUTION: In the manufacturing method for the sintered ore using a lower suction type sintered ore, coal whose volatile content is not smaller than 10 mass% is spread on the surface of a raw material filling layer which is fed with ore on a pallet of manufacturing equipment after the raw material filling layer is extracted from an ignition furnace. Since an upper layer of the sintered ore manufacturing equipment can be sufficiently heated by spreading the coal on the surface of the raw material filling layer and feeding a heat source, the product yield of the sintered core can be improved without causing the lowering or the like of the rigidity of the sintered ore caused by the insufficiency of heat.

Description

  The present invention relates to a method for producing a sintered ore.

  Production of sintered ore using a lower suction type sintering machine at a steelworks is performed as follows.

  Solid materials such as iron ore as the main raw material and iron-containing raw materials such as iron-making dust generated in the iron making process, secondary materials such as limestone and serpentine required for the sintering reaction, and coke powder as a heat source And is formed.

  Sintering raw materials are mixed and granulated while adding water using a mixing and granulating machine such as a drum mixer before being charged into the lower suction type sintering machine. A pseudo particle composed of particles and adhering powder having a particle diameter of 0.5 mm or less adhering to the periphery thereof is used.

  By this, after charging into the sintering machine, maintain the air permeability in the raw material packed layer formed in the sintering pallet, promote the sintering reaction of the sintering raw material, and ensure high productivity Can do.

The pseudo-particle-formed sintered raw material is charged into a sintering pallet at a feeding section of a sintering machine to form a raw material packed layer. Thereafter, the coke powder on the surface is ignited in an ignition furnace, and the combustion point of the coke powder is moved downward by sucking air into the lower part of the sintering machine.

Sintering reaction from the upper layer to the lower layer of the raw material packed layer proceeds sequentially by the heat of combustion, and the sintering is completed by the time the sintering pallet moves and reaches the waste ore section. The sintered cake (lumps) in the sintering pallet is discharged from the waste ore section and then crushed to produce a sintered ore for a blast furnace with a predetermined particle size.

  Sintered ore powder having a particle size smaller than a predetermined particle size as a blast furnace sinter generated in the production of sinter is blended in a sintering raw material as a return ore and sintered again.

The sintering reaction of the sintering raw material is a reaction between Fe ₂ O ₃ in the iron-containing raw material and CaO in the limestone at around 1200 ° C., and an initial melt of calcium ferrite (CaO—Fe ₂ O ₃ ) is used. Produces and proceeds by an assimilation reaction in which the iron ore or the components in the auxiliary raw material are dissolved in the melt.

  This sintering reaction is an extremely short reaction that is completed within a few minutes after the formation of the initial melt. This reaction improves the product yield and productivity of the sintered ore and the quality of the sintered ore. It is greatly affected.

  For example, if the sintering reaction proceeds excessively and the amount of melt produced increases excessively, in the sintering operation, the air flow in the sintered layer deteriorates, resulting in burn unevenness, resulting in product yield and production. As a result, the quality of sintered ore such as strength is deteriorated.

  On the other hand, if the sintering reaction does not proceed sufficiently, the melt for bonding unmelted parts such as residual iron ore (residual source ore) decreases, so the product yield decreases and the sinter strength The quality of sintered ore such as (SI) and reduced powdering (RDI) is deteriorated.

  In the production of sintered ore using a lower suction type sintering machine, the sintering raw material in the lower layer of the raw material packed bed in the sintering pallet is preheated by the combustion gas of the upper coke sucked downward, and the heat is transferred sufficiently. It is done. On the other hand, the ore in the upper layer of the raw material packed bed is not sufficiently heated by the exhaust gas, so the heat becomes insufficient. In addition, the sintered ore after firing is rapidly cooled by the air sucked from above and becomes brittle sintered ore, leading to a decrease in product yield of the sintered ore in the upper layer part and quality deterioration such as strength. It was a problem.

  Many methods have been proposed so far for improving the quality such as product yield and strength in the upper layer portion of the raw material packed bed in the production of sintered ore using the lower suction type sintering machine.

  In order to raise the temperature of the surface layer part of the raw material packed bed after ignition of the upper part of the raw material packed bed, a hood is provided above the packed bed, and a combustible gas is mixed from the hood with air or a heat retaining gas and supplied to the packed bed Has been proposed (see Patent Document 1).

  In addition, the oxygen-containing gas sucked into the sintered layer from the surface of the sintered layer after ignition is mixed with a combustible gas and a low-melting solvent, or a low-melting solvent containing a combustible gas and a carbon material, and sintered. A method of blowing into the layer has been proposed (see Patent Document 2).

  In addition, a method of igniting the surface layer after supplying fuel to the surface layer of the raw material packed layer before ignition has been proposed (see Patent Document 3).

  Further, there has been proposed a pulverized fuel spraying apparatus and method for supplying pulverized fuel in a broad and uniform manner to the surface layer of the raw material packed layer before ignition (see Patent Document 4).

JP-A-55-18585 Japanese Patent Laid-Open No. 5-311257 JP-A-60-39129 JP 2000-178661 A

  However, in the inventions described in Patent Document 1 and Patent Document 2, there is a risk of backfire or explosion of combustible gas. In addition, the gas seal of the sintering machine is not perfect, and there is a risk of leakage and diffusion of toxic components in the combustible gas.

  In addition, in the invention described in Patent Document 3, the supply of fuel is limited to the surface layer of the raw material packed layer before ignition (claim (1)), and the supplied fuel is coke or low volatile matter. There is a problem that it is limited to coal (Patent Document 3 (3) lower right).

  Moreover, in the invention described in Patent Document 4, since it is necessary to install the pulverized fuel spraying device before ignition, there is a problem that there is no room for installation space.

  The object of the present invention is to improve the product yield of sintered ore without causing a decrease in the strength of the sintered ore in the upper layer of the sintered ore, and to solidify the coal having volatile content, which has been difficult to use conventionally. It is providing the manufacturing method of the sintered ore which can be used as a fuel.

(1) A method for producing sintered ore using a lower suction type sintering machine, after 0.2 minutes have elapsed after the raw material packed bed has left the ignition furnace, and after the raw material packed bed has left the ignition furnace Within 2 minutes, the application of coal with a volatile content of 10% by mass or more to the surface of the raw material packed bed fed on the pallet within the range of 5% by mass to 15% by mass of the total blended coke amount is completed. A method for producing a sinter.
(2) The method for producing a sinter according to (1), wherein the coal has a particle size of less than 0.25 mm.

  By spraying coal on the surface of the raw material packed bed and supplying a heat source, the upper layer of the sinter production facility can be sufficiently heated, so sintering does not cause a decrease in the strength of the sinter due to lack of heat. The product yield of the ore can be improved. Furthermore, coal can be used as a part of the solid fuel, and the manufacturing cost can be reduced.

The figure which shows the method of spraying coal on the surface of a pot test and a raw material packed bed. The figure which shows the relationship between the kind of dispersion | spreading carbonaceous material, and a sintering production rate. The figure which shows the relationship between the kind of spraying carbonaceous material, and sintered ore intensity | strength. The figure which shows the relationship between the particle size of NSBC charcoal, and a sintering production rate. The figure which shows the relationship between the amount of sprayed coal, and a sintering production rate. The figure which shows the time until the spreading | diffusion completion | finish of NSBC coal dispersion, and unburned coal. The figure which shows the temperature in the position of 10 mm from the raw material filling layer surface after ignition. The raw material packed bed height direction distribution map of a low density solid (CTL).

In the production of sintered ore using a lower suction type sintering machine, the present invention sprays coal having a volatile content of 10% by mass or more on the surface of the raw material packed bed fed on the pallet of the sintered ore production facility. It is characterized by doing.
In the production of sintered ore using a lower suction type sintering machine, the sintering raw material in the lower layer of the raw material packed bed in the sintering pallet is preheated by the combustion gas of the upper coke sucked downward, and the heat is transferred sufficiently. It is done.
On the other hand, since the ore in the upper layer of the raw material packed layer is not heated by the exhaust gas, the heat is insufficient, and the sintered ore after firing is rapidly cooled by the air sucked from above and becomes brittle sintered ore.
According to the present invention, the upper layer portion of the sinter production facility can be sufficiently heated by spraying coal on the surface of the raw material packed bed and supplying a heat source, so that the strength of the sinter is reduced due to insufficient heat. It is possible to improve the product yield of sintered ore without incurring any damage.

  The higher the volatile content of the sprayed coal, the greater the effect. This is because combustion proceeds smoothly even in an environment where the surface of the raw material packed bed is easily cooled, and there is little unburned fuel. In the present invention, the main coal has a volatile content of 10 to 40%, so it is 10% by mass or more, but 19% by mass or more is more preferable.

It is preferable that the spraying of the coal on the surface of the raw material packed bed is completed within 0.2 minutes after the raw material packed bed leaves the ignition furnace after 0.2 minutes have passed since the raw material packed bed left the ignition furnace. This is because unburned coal remains on the surface of the raw material packed bed if the coal is sprayed after two minutes have passed after the raw material packed bed leaves the ignition furnace. That is, when two minutes have passed after leaving the ignition furnace, the coke combustion point ignited in the ignition furnace moves below the surface, making it difficult to completely burn the dispersed coal. The reason why 0.2 minutes have elapsed after the raw material packed bed has left the ignition furnace is that if the content is less than 0.2 minutes, the concentration of coal is high and the bed cannot be sucked.
Conventionally, solid fuel having a volatile content cannot be used in a sintering machine. This is because the volatile matter released into the exhaust gas adheres to the subsequent dust collector and blower, causing fire and vibration, respectively. However, in the present invention, the volatile matter released from the coal is completely burned when passing through the sintered combustion zone, so this problem is solved.

  The particle size of the coal to be dispersed is preferably less than 0.25 mm. This is because if the particle size is too large, it is difficult to completely burn the spread coal on the surface of the raw material packed bed.

  In order to investigate the effect of coal spraying on the surface of the raw material packed bed, a sintering pot test with a diameter of 300 mm and a bed height of 600 mm was conducted. Table 1 shows the raw material composition.

The amount of coke was 4.5% by mass (outside number) under base conditions where no coal was sprayed. Under the test conditions at the time of coal spraying, the amount of coke was 4.3% by mass (outside number), and the 0.2% by mass reduction of coke was replaced with 0.227% by mass of coal with a constant input heat amount. In this case, the coke heat generation amount was 30.2 MJ / kg, the coal heat generation amount was 26,6 MJ / kg, and the total input heat amount was 1092 MJ / t-distributed raw material for both base conditions and test conditions.
The coal application amount of 0.227% by mass is 5.28% with respect to the total blended coke amount of 4.3%.

  NSBC charcoal (volatile content 36.5 mass) and Saraji charcoal (volatile content 19.3 mass%) were used as coal.

  FIG. 1 shows a pot test and a method of spraying coal on the surface of the raw material packed bed. After mixing the raw materials in a drum mixer for 1 minute and after granulation for 4 minutes, the test pan 1 having a diameter of 300 mm is filled to a layer thickness of 600 mm, and after igniting for 90 seconds, it is sucked and baked under a constant condition of negative pressure of 15.0 kpa. I concluded. For spraying on the surface of the raw material packed bed, the coal 3 was hand-screened with a screen 4 of a predetermined mesh on the filling tank, and then sprayed on the surface of the raw material packed bed. The thermocouple 2 was arrange | positioned in each position of 120 mm, 300 mm, 450 mm, and 590 mm from the lowest layer of a raw material packed layer, and the temperature in a layer was measured. After firing, production rate, sinter strength, sinter chemical analysis and unburned coal on the surface of the sinter cake were observed. Moreover, the sintered ore after firing was analyzed by X-ray photography.

  NSBC charcoal, Saraji charcoal, and coke were used as the spread charcoal. Table 2 shows the industrial analysis and elemental analysis of NSBC coal, Saraji coal and coke.

FIG. 2 shows the results of the sintering pot test on the relationship between the type of sprayed carbon material and the sintering production rate. Moreover, the sintering pot test result about the relationship between the kind of dispersion | distribution carbon | charcoal material and the intensity | strength of sintering is shown in FIG.
In the case of a test in which NSBC charcoal (36.5% by mass of volatiles) or Saraj charcoal (19.3% by mass of volatiles) is sprinkled on the surface of the raw material packed bed compared to the base in which no charcoal is sprayed, Rate and sinter strength improved. Moreover, when compared with the case where coke was spread on the surface, the production rate and sintered ore strength were improved by the coal spread. It was found that the carbon material sprayed on the surface of the raw material packed bed is excellent in coal having a high volatile content.

For comparison, a test was also conducted in which 0.2% by mass of coke was sprayed on the surface of the raw material packed bed instead of spraying coal on the surface of the raw material packed layer. Furthermore, a test was also conducted for a case where a mixture of iron ore, quicklime and powdered coke was sprayed at a constant input heat amount so that the CaO / Fe ₂ O ₃ = 0.3 and the coke ratio was 17%. The results are shown in FIGS. Coal spraying was superior to coke and solvent surface spraying.

  In order to investigate the influence of the particle size of the coal spread on the surface, a spray test of NSBC coal (volatile content 36.5% by mass) ground to less than 0.5 mm, less than 0.25 mm, and less than 0.1 mm was performed. FIG. 4 shows the relationship between the particle size of NSBC charcoal (volatile content: 36.5% by mass) and the sintering production rate. It has been found that the particle size of the sprayed coal is more suitable less than 0.25 mm.

  In order to investigate the influence of the amount of coal sprayed on the surface, a test was performed in which the amount of coal sprayed on the surface was changed under the condition that the total mass of coke and coal was constant. The relationship between the amount of sprayed coal and the sintering productivity is shown in FIG. It turned out that the range of 5 mass% or more and 15 mass% or less is appropriate for the amount of sprayed coal.

  After igniting in the ignition furnace, a test was conducted to investigate the timing of spraying coal when spraying coal into the raw material packed bed. NSBC charcoal (less than 0.1 mm) was sprayed on the raw material packed bed immediately after leaving the ignition furnace, and the time until the end of spraying was changed. In order to make all the test conditions into the same input calorie | heat amount, 0.227 mass% coal which is a calorie | heat amount equivalent to 0.2 mass% of coke loss was sprayed. FIG. 6 shows the relationship between the time until spraying of the sprayed coal and the unburned coal. It was observed that when coal was sprayed after 2 minutes had elapsed after the raw material packed bed left the ignition furnace, unburned coal remained in the upper sintering layer. It has been found that when coal is sprayed on the raw material packed bed after ignition in the ignition furnace, the spraying must be completed within 2 minutes after leaving the ignition furnace.

In order to observe whether or not the lack of heat at the top of the raw material packed bed was eliminated by spraying coal on the surface of the raw material packed bed, the temperature at a position 10 mm from the surface of the raw material packed bed was measured. FIG. 7 shows the temperature at a position of 10 mm from the surface of the raw material packed bed when the amount of heat input is constant and 0.2 mass% of coke is replaced with NSBC coal (less than 0.1 mm), based on the case where coal is not dispersed. Shown in
It was found that the surface spray of NSBC charcoal (less than 0.1 mm) raised the temperature of the upper part of the raw material packed bed and eliminated the lack of heat.

Sintered ore after firing when the amount of heat input is constant and 0.2% by mass of coke is replaced with 0.227% by mass of NSBC charcoal (less than 0.1 mm) based on the case where coal is not applied. Analysis was performed by X-ray photography. The results are shown in FIG. Here, CTL indicates the abundance ratio of the low density solid. That is, the density (ρ) by X-ray analysis of the sintered ore at each height of the packed bed is 1.6 to 2.2 and the number of pixels is L and 2.2 to 3.4. The ratio (L / (L + M + H)) of the number of low-density pixels to the whole of each position when the number of pixels is M and H is more than 3.4 is defined as the low-density solid existence ratio (CTL).
It was found that the ratio of low density sintered ore decreased in the upper part of the raw material packed bed, and the sintering strength was improved.

  The present invention can be used in a method for producing sintered ore using a downward suction type sintering machine.

  1 ... Test pan, 2 ... Thermocouple, 3 ... Coal, 4 ... Sieve

Claims (2)

  A method for producing sintered ore using a downward suction type sintering machine, wherein 0.2 minutes have elapsed after the raw material packed bed exited the ignition furnace, and within 2 minutes after the raw material packed bed exited the ignition furnace In addition, the application of coal having a volatile content of 10% by mass or more to the surface of the raw material packed bed fed on the pallet within a range of 5% by mass to 15% by mass of the total blended coke amount is characterized by A method for producing sintered ore.   The sinter production method according to claim 1, wherein the particle size of the coal is less than 0.25 mm.

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