KR20080050508A - Process for producing sintered ore and sintering machine - Google Patents

Abstract

This invention provides a process for producing a sintered ore by feeding various gas fuels from the upper part of a charge layer of a sintering material deposited on a pallet in a sintering machine. In the process for producing a sintered ore, a gas fuel diluted to a lean flammability limit concentration or less is used as the gas fuel fed from the upper part of the charge layer on the pallet, and, in feeding the gas fuel for sintering, at least one of the feed position, charge layer highest attainable temperature, or holding time in a high temperature range is regulated to produce a sintered ore. There is also provided a sintering machine characterized by comprising a gas fuel feed apparatus.

Description

Sintering ore manufacturing method and sintering machine {PROCESS FOR PRODUCING SINTERED ORE AND SINTERING MACHINE}

The present invention relates to a method of producing a sintered ore for blast furnace raw materials using a downward suction Dwight Lloyd (DL) sintering machine, and a sintering machine used in this method.

The sintered ore which is the main raw material of the blast furnace making method is generally manufactured through the process as shown in FIG. The raw materials are iron ore powder, recovered powder in steel mill, sintered ore powder (base sieve), CaO-containing raw materials such as limestone and dolomite, granulated preparations such as quicklime, coke powder and anthracite. CaO-containing raw materials such as limestone and dolomite are hereinafter referred to as "CaO-based subsidiary materials". These raw materials are obtained from each hopper 1... Is cut out at a predetermined rate from the conveyor. The cut raw material is mixed and subsequently granulated while adding an appropriate amount of water by the drum mixer 2 or the like to form a sintered raw material which is a pseudo particle having an average diameter of 3.0 to 6.0 mm. The formed sintered raw material is dried in a kiln 3. The dried sintered raw material is charged from the surge hoppers 4 and 5 arranged on the sintering machine through the drum feeder 6 and the charging chute 7 onto the endless movable sintering machine pallet 8, A charging layer 9, also called a sintered bed, is formed. The thickness (height) of the charge layer is around 400 to 800 mm. Thereafter, the ignition furnace 10 provided above the charging layer 9 ignites the carbonaceous material in the charging layer. By suctioning downward through the wind box (wind box) 11 arranged below the pallet 8, the carbonaceous material in the said charging layer is burned sequentially and the said sintering is carried out by the heat of combustion which generate | occur | produces at this time. The fuel is sintered and melted to produce a sintered cake. Then, the obtained sintered cake is sintered after crushing, and it collect | recovers as a characteristic sintered ore which consists of compacts of 5.0 mm or more.

In the manufacturing process, first, ignition is performed on the surface of the charging layer by the ignition furnace 10. The carbonaceous material in the charging layer is burned by the action of the suction gas sucked from the top of the charging layer to the lower layer, and the combustion proceeds gradually to the lower layer and to the front as the pallet 8 moves. At the same time as the combustion progresses, the water of the sintered raw material particles in the charged layer is evaporated by the heat generated by the burning of the carbonaceous material but is sucked to the lower side and concentrated in the sintered raw material of the lower wetted zone where the temperature has not yet risen. When the moisture concentration is increased to a certain degree or more, the moisture fills the voids between the raw material particles which are the flow paths of the suction gas, thereby increasing the ventilation resistance. Moreover, the part which melt | dissolves which is necessary for a sintering reaction also raises air permeability.

The production amount of sintered ore (t / hr) is generally determined by the sintering production rate (t / hr · m 2) × sintering machine area (m 2). In other words, the amount of production varies depending on the size and length of the sintering machine, the thickness (loading layer thickness) of the raw material deposition layer, the bulk density of the sintering raw material, the sintering (burning) time, the yield, and the like. In order to increase the production of the sintered ore, a method of improving the air permeability (pressure loss) of the charged layer to shorten the sintering time, or the method of improving the yield by improving the cold strength of the sintered cake before crushing is effective. Is considered.

2 is a graph showing the distribution of pressure loss and temperature in the charge layer. The temperature distribution curve of FIG. 2 shows when the combustion (flame) wire which moves in a charge layer is in the position of about 400 mm on the pallet in the thickness direction of the said charge layer. At this time, the pressure loss distribution was about 60% in the wet zone and about 40% in the combustion melting zone.

3 shows the temperature distribution in the charged layer during high production and low production of sintered ore. The high temperature zone holding time maintained at a temperature of 1200 ° C. or more at which raw material particles begin to melt is represented by t ₁ for low production and t ₂ for high production that emphasizes productivity. In the case of high production, the pallet speed needs to be raised, and the high temperature zone holding time t ₂ becomes shorter than the high temperature zone holding time t ₁ at low production. Since the time kept at high temperature becomes short, baking becomes insufficient, the cold strength of sintered ore is brought down and a yield falls. Therefore, in order to improve the yield of high strength sintered ore, it is considered that it is effective to raise the strength of the sintered cake, that is, the cold strength of the sintered ore, and to maintain and improve the yield by any method. In addition, SI (shutter index) and TI (tumbler index) are used for sintered ore cold strength.

Figure 4 (a) shows the principle of sintering the charging layer on the sintering machine pallet, Figure 4 (b) shows the temperature distribution (heat pattern) of the sintering process in the charging layer, Figure 4 (c) is sintering The yield distribution of the cake is shown. As can be seen from FIG. 4B, the temperature of the charged layer upper part (sintered layer) is less likely to increase compared to the lower layer part, and the high temperature zone holding time is shortened. As a result, combustion melting reaction (sintering reaction) becomes insufficient at the upper part of the charging layer, and as shown in Fig. 4C, the strength of the sintered cake is lowered, so that the yield does not increase and the productivity decreases. It becomes a tendency.

Conventionally, a method for imparting high temperature maintenance on the charge layer has been proposed.

Japanese Patent Laid-Open No. 48-18102 discloses injecting a high concentration of flammable gas immediately after an ignition furnace. Since the amount of coal ash is not reduced at the time of blowing the combustible gas, the inside of the sintered layer becomes a high temperature exceeding 1380 degreeC, and sufficient cold strength improvement and the improvement of a yield increase cannot be enjoyed. Moreover, injecting flammable gas for 0 to 2 minutes immediately after an ignition furnace has a high risk of igniting a flammable gas and causing a big fire, and is a technique with low practicality, and has not reached practical use.

In addition, Japanese Patent Application Laid-Open No. 55-18585 has a hood disposed on the charging layer in order to keep the charge layer of the sintered raw material at a high temperature, and the mixed gas with air or coke oven gas is supplied through the hood. Blowing in the position immediately after an ignition furnace is started. The temperature in the sintered layer becomes a high temperature exceeding 1350 ° C., and the effect of blowing is not possible, and the flammable mixed gas ignites and there is a danger of a big fire, and it is not put to practical use.

In addition, Japanese Patent Application Laid-open No. Hei 5-311257 discloses a method of blowing a low melting point solvent and carbonaceous material or flammable gas at the same time immediately after the ignition furnace. This method also blows flammable gas in a state where a flame remains on the surface, and the effect of high fire is high and the width of the sintering stand is not thick enough (about 15 mm or less), so that the effect can be sufficiently exhibited. none. In addition, since there are many low melting point solvents, this causes excessive melting in the upper layer, prevents pores, which are air flow paths, worsens air permeability, and leads to a decrease in productivity. It is not put to practical use.

As mentioned above, all of the conventional techniques proposed so far have not been put to practical use, and the search for blowing conditions that are economically established has been hopeless.

In adjusting the quality of the sintered ore, it is important to adjust the maximum temperature at the time of combustion, the holding time of the high temperature region, and the like, and the sintered ore quality is determined by these adjustments. In this regard, the method described in Japanese Patent Application Laid-Open No. 48-18102 is a technique of raising the temperature of the charged layer upper part of the first half of the sintering process by burning gaseous fuel on the surface of the charged layer. However, in this method, the concentration of gas fuel is high, and therefore, the amount of air (oxygen) that supports combustion is insufficient, which may lead to a reduction in the combustion of carbon materials (coke) of the sintered raw material. There is a problem. The method described in Japanese Patent Laid-Open No. 55-18585 is a method of obtaining a further high temperature by installing a hood and supplying flammable gas together with combustion air, but this method also causes a shortage of calories. In other words, this method also suffers from a problem that the combustion of coke is delayed and the sintering time is long because oxygen required for the combustion of coke is blown in the high temperature zone and consumed for combustion of the combustible gas.

In addition, the method described in Japanese Patent Application Laid-open No. Hei 5-311257 increases the amount of air (oxygen) and mixes low melting point materials and carbonaceous materials so that the combustion speed of flammable gas and coke increases, but low melting point materials Since blowing powder together, there exists a problem that the air permeability of combustion air falls.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a high strength sintered ore at high yield and a sintering machine used to carry out the method without deteriorating the air permeability of the entire charging layer in the operation of the downward suction type sintering machine. will be.

In order to achieve the above object, the present invention charges the sintered raw material including the spectroscopy and carbon material on the circulating moving pellets, the charging step of forming a charging layer containing the carbon material on the pallet; An ignition step of igniting carbon material on the surface of the charging layer in the ignition furnace; A firing step of sucking air through a windbox disposed below the pallet, burning carbonaceous material in the charging layer, and generating a sintered cake by the heat of combustion generated; Provided is a method of producing a sintered ore having a gas fuel combustion process of supplying a gas fuel diluted to a lower combustion lower concentration from above a charging layer and burning the gas fuel in the charging layer.

The gas fuel combustion process supplies gaseous fuel diluted below the lower combustion limit concentration from above the charging bed, burns the gaseous fuel in the charging bed, the maximum reaching temperature in the charging bed or the high temperature zone holding time in the charging bed, Or it is preferable to consist of adjusting the maximum reaching temperature and high temperature area holding time in a charge bed.

It is preferable to adjust the highest reaching temperature in the charged layer in the following aspects.

(A) The gaseous fuel diluted below the lower combustion limit concentration is supplied from above the charging bed, and the maximum reaching temperature in the charging bed is adjusted.

(B) The highest reaching temperature in the charged bed is adjusted by supplying gaseous fuel diluted below the lower combustion limit and adjusting the amount of carbonaceous material in the sintered raw material.

(C) The gaseous fuel diluted below the lower combustion limit is supplied from above the charging bed, the gaseous fuel supply is adjusted, and the maximum reaching temperature is adjusted.

(D) The highest reaching temperature is adjusted by supplying gaseous fuel diluted to the lower combustion lower concentration from above the charging bed and adjusting the amount of carbonaceous material and the amount of gaseous fuel in the sintered raw material.

In said (A)-(D), it is preferable to adjust the said highest reaching temperature to 1205 degreeC-1350 degreeC.

It is preferable to perform adjustment of the high temperature zone holding time in the said charging layer in the following aspect.

(a) The gaseous fuel diluted below the lower combustion limit is supplied from above the charging bed, and the holding time of the high temperature zone in the charging bed is adjusted.

(b) The gaseous fuel diluted below the lower combustion limit concentration is supplied from above the charging bed, the concentration of the gaseous fuel is adjusted according to the amount of carbonaceous material in the sintered raw material, and the high temperature zone holding time in the charging bed is adjusted.

Moreover, it is preferable that the said gaseous fuel combustion process consists of adjusting the form of a combustion-melting zone in the following aspect.

(A) The gaseous fuel diluted below the lower combustion limit is supplied from above the charging bed, and the shape of the combustion and molten zone is adjusted.

(B) The gaseous fuel diluted below the lower combustion limit concentration is supplied from above the charging layer, and the high temperature holding time of the combustion and melting zone is extended to adjust the cold strength of the sintered ore.

(C) The gaseous fuel diluted below the lower combustion limit concentration is supplied from above the charging bed so that at least a part thereof remains unburned and reaches the combustion and melting zone in the charging bed, and the shape of the combustion and melting zone is adjusted. It is more preferable to adjust the thickness in the height direction of the combustion and melting zone and / or the width in the pallet moving direction.

In addition, it is preferable to perform the gas fuel combustion process in the following aspects with respect to the supply position of the gas fuel.

(a) The gaseous fuel diluted below the lower combustion limit is supplied from above the charging bed, the gaseous fuel is combusted in the charging bed, and the supply position of the gaseous fuel to the charging bed is adjusted.

(b) The gaseous fuel diluted below the lower limit of combustion at the position after the ignition furnace is supplied from above the charging bed, and the gaseous fuel is combusted in the charging bed.

(c) The gaseous fuel diluted below the lower limit of combustion concentration is supplied in the area | region where the thickness of a combustion-melting zone becomes 15 mm or more, and the said gaseous fuel is combusted in a charge bed.

(d) After the position where the precombustion line reaches 100 mm below the surface layer, the gaseous fuel diluted below the lower combustion limit is supplied, and the gaseous fuel is combusted in the charging bed. It is more preferable to supply gaseous fuel having a concentration below the lower combustion limit after the position where the combustion wire reaches 200 mm below the surface layer.

(e) The gaseous fuel diluted below the lower combustion limit is supplied to both sidewalls of the said charging bed, and the said gaseous fuel is combusted in the charging bed.

(f) The gaseous fuel diluted below the lower combustion limit is supplied from above the charging layer in the sintering machine length direction, the gaseous fuel is combusted in the charging layer, and the cold strength of the sintered ore is adjusted.

The gaseous fuel is preferably a flammable gas which is 75% or less of the lower limit of combustion and is diluted to a concentration of 2% or more. More preferred is a flammable gas of 60% or less of the lower combustion limit and diluted to a concentration of 2% or more, and more preferably a flammable gas of 25% or less of the lower combustion limit and also diluted to a concentration of 2% or more.

The gaseous fuel is preferably at least one gas selected from the group consisting of blast furnace gas, coke oven gas, blast furnace-coke oven mixed gas, propane gas, natural gas and methane gas.

In addition, the present invention is provided with a circulating pallet, a suction wind box disposed below the pallet, a raw material supply device for supplying the sintered raw material on the pallet, and an ignition furnace for igniting the carbon material in the sintered raw material A sintering machine comprising: a gaseous fuel supply device for discharging gaseous fuel diluted at a concentration equal to or lower than the lower combustion lower concentration from the charging bed into the charging bed on a downstream side of the ignition furnace; Provide a flag.

Preferably, at least one gas fuel supply device is disposed in the length direction of the sintering machine downstream of the ignition furnace.

More preferably, the gaseous fuel supply device is disposed at a position between sintering and completion at the stage where the combustion wire proceeds below the surface layer in the pallet traveling direction.

In addition, it is preferable that the gas fuel supply device is disposed in the vicinity of the sidewall.

1 is an explanatory diagram of a sintering process,

2 is a graph of pressure loss and temperature distribution in a sintered layer,

3 is a graph of the temperature distribution during high production and low production,

4 is a graph of temperature distribution and yield distribution in a sintering machine,

5 is an explanatory diagram of a gas fuel blowing process according to the present invention;

6 is a view showing the transition of the combustion molten metal in the test pot (test) showing the experimental results for the method of the present invention (photo),

7 is a comparison graph for the sintering pot test results,

8 is a view for explaining a method for calculating the combustion limit of gaseous fuel;

9 is an explanatory diagram showing a temperature dependency of combustion;

10 is a view showing the effect of the gas species at the time of blowing gas fuel,

11 is an explanatory diagram showing the relationship between the blown gas concentration, shutter strength, yield, sintering time, and production;

12 is a schematic diagram of a sintering reaction,

FIG. 13 is a schematic diagram of a process for producing a skeleton crystallin secondary hematite;

14 is an observation diagram (photograph) of the combustion limit at the time of dilution propane blowing;

15 is a view showing the influence of the blowing position;

16 is a view showing the influence of the blowing position;

17 is an explanatory diagram of a layer temperature distribution in sintering;

18 is an explanatory diagram of a result of verifying the influence of the blowing position;

19 is a graph of changes over time of the charge bed temperature (a), exhaust gas temperature (b), passage air flow amount (c), and exhaust gas composition (d) at the time of dilution propane blowing;

FIG. 20 is a graph of the change over time (time lapse) of the temperature (a), (a '), exhaust gas temperature (b), and (b') in the charged bed at the time of dilution propane blowing and coke-only increase.

21 is a graph showing sintering characteristics test results under various blowing conditions;

22 is a comparative graph showing a change in the mineral composition ratio under various blowing conditions;

23 is a graph showing a change in apparent specific gravity of quality sintered ore,

24 is a pore diameter distribution graph of 0.5 mm or less in quality sintered ore,

25 is a schematic diagram of the sintering behavior when using only coke (a) and gas blowing (b),

Figure 26 is a schematic diagram of the pore structure at the time of blowing the diluent gas,

27 is a graph of the experimental results of grasping the limit coke ratio that can maintain cold strength,

28 is a diagram (photograph) showing the result of Example 1;

29 is a diagram showing the results of Example 2 (photograph).

[Description of the code]

One; Raw material hopper 2; Drum mixer

3; Rotary kilns 4, 5; Surge hopper

6; Drum feeder 7; Charging suit

8; Pallet 9; Charging layer

10; 11 as ignition; Wind box

12; Gas Fuel Supply Device

The manufacturing method of the sintered ore which concerns on this invention has a charging process, an ignition process, a baking process, and a gas fuel combustion process. The charging process consists of charging a sintered raw material including spectroscopy and carbonaceous material on a pallet which is circulating and forming a charging layer containing carbonaceous material on the pallet. The ignition step consists of igniting carbon material on the surface of the charge layer in the ignition furnace. The firing process consists of sucking air through a windbox disposed under the pallet, burning the carbonaceous material in the charging layer, and producing a sintered cake by the heat of combustion generated. The gas fuel combustion process supplies a gas fuel diluted to a lower combustion lower concentration from above the charging bed, and burns the gas fuel in the charging bed. This gas fuel combustion process is one of the characteristics of the present invention.

In the gas fuel combustion process, as the gas fuel, it is preferable to use a combustible gas in which the content of the combustion component is diluted to 75% or less below the lower limit of the combustion at normal temperature in the air. More preferably, as the gaseous fuel, a flammable gas diluted to 60% or less, more preferably a flammable gas diluted to a concentration of 25% or less is used. The following two reasons are preferable to use a flammable gas diluted to 75% or less of the lower combustion limit.

(a) Since the supply of the above-mentioned gaseous fuel to the upper part of the charging layer may sometimes cause explosive combustion, at least at room temperature, even if there is an ember, the combustion is not performed.

(b) A state in which there is no possibility of burning under the discharge of the electrostatic precipitator, even if it reaches the electrostatic precipitator on the downstream side of the sintering machine without being completely burned on the sintering machine (in the charging layer), that is, the lower combustion limit. Execution under the following conditions.

In addition, as will be described later, the concentration of this gaseous fuel may be diluted so as to cause a lack of air (oxygen) necessary for the combustion of the total carbonaceous material (solid fuel + gaseous fuel) in the sintered raw material and not to become insufficient in combustion. There is a need. The gaseous fuel is preferably a flammable gas diluted to a concentration of 2% or more of the lower combustion limit. If the concentration is 2% or more, the strength and yield of the sintered ore is further improved. In addition, the gas fuel adjusts its concentration according to the amount of carbonaceous material (solid fuel). In addition, as described later, the gaseous fuel can adjust combustion at a predetermined region position in the charging layer by diluting this.

In the method for producing a sintered ore according to the present invention, after being ignited by the carbonaceous material in the charged layer, the diluted gaseous fuel is supplied to the charged layer. In the position immediately after ignition, even when the diluent gas fuel is supplied, combustion only occurs on the surface layer, and does not have any effect on the sintered layer. After the sintered raw material is fired in the upper part of the charging layer to form a layer of the sintered cake, it is preferable to supply the diluted gas fuel to the charging layer. The supply of diluted gaseous fuel can be performed at any position as long as the layer of sintered cake is formed. The reason for carrying out the supply of the diluted gas fuel after the layer of the sintered cake is formed is as follows.

(a) If this gaseous fuel is supplied in the state where no sintered cake has yet been formed on top of the charging layer, there is a risk of explosive combustion on the charging layer.

(b) The supply of gaseous fuel is to be provided where the yield needs to be improved. That is, it is effective to supply to the part to raise sintered ore intensity.

Dilution is carried out under conditions such that the thickness of the combustion and melting zone is at least 15 mm, preferably at least 20 mm, more preferably at least 30 mm, in order to adjust either the charging bed maximum reaching temperature or the high temperature zone holding time. It is preferable to carry out the supply of gaseous fuel. If it is less than 15 mm, it is accompanied by cooling by the atmosphere (mixed gas of air and gas fuel) sucked through the sintered layer (sintered cake). The effect of supply is insufficient. When the gaseous fuel is diluted and supplied at a stage in which the thickness of the combustion and melting zone becomes 15 mm or more, preferably 20 mm or more, more preferably 30 mm or more, the thickness of the combustion and melting zone is greatly expanded, and the high temperature zone is increased. The retention time is extended.

In addition, confirmation of the thickness of the combustion and molten zone can be confirmed using, for example, a transparent quartz window or a vertical tubular test port, which contributes to the determination of the supply position of the diluted gas fuel.

In addition, it is preferable to supply the diluted gas fuel at a position where the combustion wire is lowered below the surface layer and the combustion / melting zone is lowered by 100 mm or more, preferably 200 mm or more from the surface layer. That is, it is preferable to supply the diluted gas fuel for the lower middle layer area | region. For example, the diluent gaseous fuel may be used as a ratio in the lower middle portion of the charged layer after the sintered cake is formed in the charged layer, that is, when the combustion wire is moved 100 mm from the surface layer (to reach the region without being burned). Dilute gaseous fuel is supplied to combust. The reason for this is that if the position is lowered by 100 mm or more, the effect of cooling by the air drawn through the sintered layer is reduced, and the thickness of the combustion and melting zone is accompanied. More preferably, if it is 200 mm or more, the influence accompanying cooling by air | atmosphere is eliminated, and the thickness of a combustion-melting zone expands to 30 mm or more. Moreover, it is more preferable to perform this supply at the both ends of the width direction (direction orthogonal to a pallet advancing direction) of the vicinity of the sidewall in which a yield fall is remarkable.

In addition, the gas fuel supply device varies depending on the size of the sintering machine, but is, for example, a sintering machine having a gas fuel supply amount of 1000 to 5000 m 3 (standard) / h and about 150,000 t / day-length 90 m. It is preferable to arrange at a position after about 5 m on the downstream side of.

In the manufacturing method according to the present invention, the supply position of the diluent gas fuel is a position where the so-called combustion wire after the sintered cake is formed at the exit side of the ignition furnace in the pallet movement direction is below the surface layer (for example, 100 below the surface layer). It is preferable to carry out at one or more arbitrary positions between the mm and, preferably, about 200 or less, from where the combustion of the gaseous fuel occurs) until the sintering is completed. In other words, this means starting the supply of the gaseous fuel at the stage where the combustion wire has moved below the surface layer of the charging bed as described above, which means that combustion of the gaseous fuel takes place inside the charging bed, and gradually By moving to the lower layer, it means that there is no fear of explosion and safe sintering operation is possible.

In the production method according to the present invention, the supply of diluent gas fuel to the charging bed also means that the reheating of the resulting sintered cake is promoted. That is, since this gas fuel supply is likely to be short of heat due to a short high temperature zone holding time, the gas fuel, which is more reactive than the supply of solid fuel, is supplied to the sintered cake having low cold strength of the sintered ore. This is because it has the meaning of regeneration-expansion of combustion and molten zone and maintenance of the heat of combustion of this part which is likely to be insufficient.

In the method for producing a sintered ore according to the present invention, at least a part of the gaseous fuel supplied from the upper part of the charged layer after ignition is unburned and sucked (introduced) to the combustion / melting zone and supplied to be burned at a target position. desirable. This is because it is considered that the effect of supplying gaseous fuel, that is, blowing into the charging bed, is more effective not only at the top of the charging bed, but also at the combustion and melting zone in the center of the thickness direction. This is because when the gaseous fuel supply is carried out in the upper part of the charging bed which is likely to be heat deficient (lack of high temperature holding time), it leads to providing sufficient heat of combustion, and can improve the quality (sinter strength) of this part. . In addition, if the gaseous fuel supply action spreads to the zone below the central portion, the result is equivalent to the formation of reburning and melting zone on the original combustion / melting zone, leading to widening in the vertical direction of the band. It is possible to extend the high temperature zone holding time without raising the reaching temperature, and sufficient sintering is realized without lowering the pallet speed. As a result, quality improvement (improvement of cold strength) of the sintered cake of the whole charging layer is brought about, and also it leads to the improvement of the quality (cold strength) and productivity of a characteristic sintered ore.

In the present invention, the supply of the diluent gas fuel has a first feature in that the supply position is adjusted in view of the effect of the supply in the charging bed. The second feature is that the maximum reaching temperature and the high temperature zone holding time in the inside are adjusted to some extent according to the amount of solid fuel under a certain amount of heat.

Therefore, in the present invention, in the supply of the diluent gas fuel to the charging bed, not only the position of the supply is adjusted, but also the shape of the combustion and the molten metal itself is adjusted, and further, the highest arrival in the combustion and molten metal is reached. It is also desirable to adjust the temperature and / or hot zone holding time.

In general, the charged layer after ignition has the position of the combustion / melting zone shown in Fig. 4 (a) while the combustion (flame) wire gradually expands downward and forward (downstream) as the pallet moves. Change as follows. And, as shown in Fig. 4 (b), the thermal history received during the sintering process in the sintered layer is different in the upper layer, middle layer, and lower layer, as shown, the high temperature zone holding time (about 1200 ℃ or more between upper and lower layers) ) Is very different. As a result, the sintered layer has a yield distribution as shown in Fig. 4C. In other words, the yield of the surface layer portion (upper layer) is low, resulting in a high yield distribution in the middle and lower layer directions. Therefore, according to the method of the present invention, when the gas fuel is supplied, the combustion / melting zone changes in the direction in which the thickness width, the range, and the like in the vertical direction are enlarged, which is reflected in the improvement of the quality of the sintered ore. And since the middle layer and the lower layer which become high yield distribution can also adjust high temperature area holding time, a yield can be raised further.

By adjusting the supply position of the gaseous fuel, it is possible to adjust the shape of the combustion / melting zone, that is, the thickness in the height direction and / or the pallet movement direction of the zone, and at the same time adjust the maximum reaching temperature or the high temperature zone holding time. Leads to. These adjustments further improve the effect of the present invention, and always achieve sufficient firing by adjusting the thickness width in the vertical direction of the combustion and melting zones, adjusting the maximum reaching temperature, and maintaining the high temperature zone, thereby improving the cold strength of the sintered ore. Contributes effectively.

In the present invention, the supply of the gaseous fuel to the charging layer may be for adjusting the cold strength of the whole sintered ore. In this regard, the purpose of performing the blowing of the gas fuel is originally to improve the cold strength of the sintered cake and further to the sintered ore, in particular, to adjust the gas fuel supply position and the time for the sintered raw material to stay in the combustion and molten zone. Through the adjustment of the high temperature zone holding time and the maximum reaching temperature, the cold strength (shutter index SI) of the sintered ore is set to about 75% to 85%, preferably 80% or more, more preferably 90% or more. It is.

In the case of the present invention, this strength level is adjusted by adjusting the concentration, the supply amount, the blowing position, and the blowing range of the gaseous fuel, in particular, taking into account the amount of carbonaceous material in the sintered raw material (under the condition of keeping the heat input constant). It can be achieved at low cost. In addition, the improvement of the cold strength of the sintered ore may lead to an increase in the ventilation resistance and a decrease in the productivity on the one hand. However, in the present invention, after solving such a problem by adjusting the maximum reaching temperature or the high temperature zone holding time, Improve strength. In addition, the said cold strength SI value shows the SI value 10%-15% higher than the pot test value in the case of the sintered ore manufactured by the actual sintering machine.

In the manufacturing method of the present invention, the adjustment of the feed position of the gaseous fuel in the pallet moving direction is how the cold strength of the sintered ore in any band from the sintered cake produced in the charging bed to the wet zone is to be done. It is a standard. For this adjustment, in the present invention, the size (size), number, position (distance from ignition), and gas concentration of the gas fuel supply device are preferably adjusted according to the amount of coal ash (solid fuel) in the sintered raw material. In addition, not only the size of the combustion / melting zone (width in the vertical direction and the pallet moving direction), but also the maximum reaching temperature and the high temperature zone holding time are adjusted, thereby adjusting the strength of the sintered cake produced in the charging layer.

In the above production method of the present invention, it is preferable to use any one of blast furnace gas, coke oven gas, blast furnace-coke oven mixed gas, propane gas, natural gas or methane, or a mixture of these gases. These all contain combustion components, which are diluted with air or the like and used as gas fuel having a concentration of about 75% or less of the lower combustion limit. In addition, the dilution of gaseous fuel may be dilution by inert gas, inert gas and oxygen, inert gas and air, or a combination of air and oxygen in addition to air.

In the execution of the method for producing a sintered ore according to the present invention, a suction wind box is disposed under a pallet moving with a loading layer of sintered raw material, and on the pallet, the raw material supply device and the pallet traveling direction downstream of the device. A side suction DL sintering machine comprising an ignition furnace on the side, wherein a gaseous fuel supply for blowing gas fuel diluted in the concentration below the lower combustion limit from the top of the charging layer into the charged layer on the downstream side of the ignition furnace. The sintering machine which arrange | positions and arranges an apparatus is used.

In the present invention, the gas fuel supply device is preferably disposed so as to ride over both sidewalls of the pallet along the width direction of the sintering machine. The gas fuel supplying device is provided with a blown hood for supplying diluted gas fuel, or a gas blown or diluted gas fuel supply blown pipe formed by thermally installing a slit shape or a blow nozzle in a plate shape in the blown hood. It is preferable to consist of one.

Further, the gaseous fuel supply device is disposed downstream of the ignition furnace and is disposed at one or more positions in any one of the pallet traveling directions in the course of the combustion and the molten metal proceeding in the charging bed. The gas fuel is preferably supplied at a position after ignition to the carbonaceous material in the charging bed. That is, the apparatus is one or more arranged at an arbitrary position after the downstream side of the ignition furnace and the wire before the combustion proceeds below the surface layer, and in view of adjusting the cold strength of the target sintered ore, , Position and number are adjusted. The gas fuel supplying device is to be arranged at a position of low yield near the sidewalls, and the gaseous fuel uses flammable gas diluted to 75% or less of the lower limit of combustion limit and diluted to 2% or more. Furthermore, it is preferable to use a flammable gas which is 60% or less of the lower combustion limit and diluted to a concentration of 2% or more.

As described above, according to the present invention, in the operation of the lower suction type sintering machine, it is possible to burn at a target position in the charging layer by using diluted gas fuel from the upper side of the charging layer, and in this case, By adjusting the feed position of the diluted gas fuel, the maximum reaching temperature during combustion, and the high temperature zone holding time, not only the upper part of the charging layer which is liable to become insufficient in combustion and lowers the cold strength of the sintered ore, but also below the middle layer of the charging layer. Operation such as raising the sintered ore strength of any part can be performed. In addition, in the present invention, without deteriorating the air permeability of the entire charging layer, in particular, the reaction in the combustion and melting zone, for example, by adjusting the width in the vertical direction and the width in the pallet moving direction of this zone, Since the intensity | strength of the sintered cake in the position of can be adjusted, the characteristic sintered ore with high cold strength as a whole sintered ore can be manufactured by ensuring a high yield and high productivity. And using the sintering machine of this invention, operation of such a sintering machine can be performed stably.

5 shows one embodiment of an apparatus for producing sintered ore according to the present invention. This invention is not limited only to the form of this illustration. The upper side of the charging layer in which a gaseous fuel supply device (hood) 12 for blowing gaseous fuel, such as blast furnace gas and coke furnace gas (M gas), reaches downstream of the pallet moving direction of the ignition furnace 10. Only 1 unit is installed in the unit. The gas fuel supply device 12 includes a plurality of pipe-shaped gas injection nozzles 12a arranged in a plurality in a downward direction and in an aeration direction. The plurality of pipe-shaped gas injection nozzles 12a are disposed to cover the charging layer from the sidewalls not shown through the gas fuel supply device 12. The M gas supplied from the gaseous fuel supply device 12 is attracted by the wind box 11 below the pallet 8 to the core portion (lower layer) of the charging layer via the sintered cake produced on the surface layer from above the charging layer. Is inhaled using. Moreover, when aiming at the yield improvement of the area | region where the yield shown to Fig.4 (c) is low as 60%, the nozzle 12a of the said nozzle 12a can be supplied so that a lot of gaseous fuel can be supplied to the position of the pallet near both sidewalls. It is desirable to carry out the batch.

As the gaseous fuel supplied from this gaseous fuel supply apparatus 12, for example, blast furnace gas (B gas), coke gas (C gas), mixed gas (M gas) of blast furnace gas and coke oven gas, propane gas, natural Diluted gas (LNG) or methane or these mixed gases is used. These gaseous fuels may be supplied under a piping system independent of the ignition furnace 10. In addition, the gas supply pipe to the ignition furnace 10 (not shown) is arranged in a pipe common to the ignition furnace fuel pipe, especially with a dilution gas introduction pipe, and dilutes and adjusts the concentration of the gas fuel below the lower combustion limit. May be connected to an extension phase.

Table 1 below shows examples of the lower combustion limit concentrations and the blowing concentration upper limits (75%, 60%, 25%) of the various gas fuels used in the present invention.

For example, in the case of propane gas, the lower combustion limit is 2.2 vol%, the upper limit of the blowing gas concentration diluted to 75% is 1.7 vol%, and the upper limit of the blowing gas concentration diluted to 60% is diluted 1.3 vol% and 25%. Blown gas concentration is 0.4 vol%. The concentration at which the effect of blowing starts to appear, that is, the lower limit of the diluted blowing gas concentration is 0.05 vol%. Therefore, the preferable range is as follows.

Preferred range (1): 2.2 vol%-0.05 vol%

Preferred range (2): 1.7 vol% to 0.05 vol%

Preferred range (3): 1.3 vol%-0.05 vol%

Preferred range (4): 0.4 vol% to 0.05 vol%

In case of C gas, the lower combustion limit is 5.0 vol%, the upper limit of blowing gas concentration diluted to 75% is 3.8 vol%, and the upper limit of blowing gas concentration diluted to 60% is 3.0 vol% and the blowing gas concentration diluted to 25% is 0.9 vol%. The concentration at which the effect of blowing starts to appear, that is, the lower limit of the diluted blowing gas concentration is 0.24 vol%. Therefore, the preferable range is as follows.

Preferred range (1): 5.0 vol%-0.24 vol%

Preferred range (2): 3.8 vol%-0.24 vol%

Preferred range (3): 3.0 vol%-0.24 vol%

Preferred range (4): 0.9 vol% to 0.24 vol%

For LNG, the lower combustion limit is 4.8 vol%, the upper limit of blow gas concentration diluted to 75% is 3.6 vol%, and the upper limit of blow gas concentration diluted to 60% is 2.9 vol% and the blow gas concentration diluted to 25% is 0.9. vol%. The lower limit of the diluted blowing gas concentration is 0.1 vol%. Therefore, the preferable range is as follows.

Preferred range (1): 4.8 vol%-0.1 vol%

Preferred range (2): 3.6 vol% to 0.1 vol%

Preferred range (3): 2.9 vol%-0.1 vol%

Preferred range (4): 0.9 vol%-0.1 vol%

In the blast furnace gas, the lower combustion limit was 40.0 vol%, the upper limit of the blown gas concentration diluted to 75% was 30.0 vol%, and the upper limit of the blown gas concentration diluted to 60% was 24.0 vol%, and the blown gas concentration diluted to 25% was 7.6 vol%. The lower limit of the diluted blowing gas concentration is 0.24 vol%. Therefore, the preferable range is as follows.

Preferred range (1): 40.0 vol%-1.25 vol%

Preferred range (2): 30.0 vol%-1.25 vol%

Preferred range (3): 24.0 vol%-1.25 vol%

Preferred range (4): 7.6 vol%-1.25 vol%

Next, Table 2 shows the content and calorific value of hydrogen, CO, methane, ethane and propane as combustion components of C gas, LNG and B gas.

Next, the experiment which became an opportunity to develop the manufacturing method of the sintered ore which concerns on this invention is demonstrated.

This experiment was carried out using the experimental apparatus shown in Fig. 6, that is, a vertical tubular test port (1500 mm φ x 400 mm H) having a transparent quartz window, and a mixed gas of blast furnace gas-coke furnace gas as a gaseous fuel to be used. It is an example which operated on the conditions of constant suction pressure of 11.8 Kpa using (M gas) and using the same sintering raw material used in the sintering plant of the applicant company, ie, the sintering raw material shown in Table 3. Here, the concentration of the combustion component of the M gas is an example of dilution with air to vary within the range of 0.5 vol% to 15 vol%. In addition, the lower limit of combustion of M gas used for this experiment is 12 vol%.

Type of raw materials Mass%  Robe River 9.6  Yandi 23.8  Carajas 42.6  Limestone 16.6  burr 2.7  Bunk coke 4.7

Fig. 6 also shows the video observation from the transparent quartz window, in particular the falling situation accompanying the movement of the wire before combustion. As can be seen from FIG. 6, when a gaseous fuel containing 15 vol% of M gas exceeding the lower limit of combustion (12 vol%) is injected into the raw material deposition layer in the test port, the gaseous fuel immediately combusts at the charge layer surface. It did not reach to the lower layer of the charging layer, and the effect of blowing was small. On the contrary, according to the present invention, when gaseous fuel diluted with air up to 3 vol%, which is 75% or less of 12 vol% of the lower limit of combustion of the gaseous fuel is used, it is not burned on the surface of the raw material deposition layer, and the charging layer It reached the depth inside, that is, the considerable range of combustion and molten metal. As a result, the thickness of the combustion zone (also called combustion and melting zone) when sintered in the air was 70 mm, whereas in this example, the thickness width of the combustion zone could be increased to 150 mm, that is, more than twice. In other words, the expansion of the thickness of the combustion zone is inevitably extended to the high temperature zone holding time.

In the experiment by the test port, the falling speed of the combustion zone corresponding to the progress of the combustion wire accompanying the movement of the pallet in the practical sintering machine (this reciprocal is the sintering time) is determined by the dilution gas fuel. It became faster by supply, and the thickness width of the up-and-down direction of the combustion table could be enlarged so that it might be the same as when the coke was extended and the high temperature air was blown in. Thus, when the gaseous fuel diluted suitably in the charging layer of the sintering raw material is blown, compared with the case of using the conventional solid fuel, liquid fuel, and undiluted combustible gas, this widening effect of this combustion width becomes remarkable, In addition, it was found that the drop speed of the combustion wire proceeded at the same speed almost unchanged as in the case of atmospheric sintering.

7A to 7D summarize the sintering pot test results in the above experiment. According to this result, in the case where M gas properly diluted in the raw material charging layer was blown in accordance with the present invention, the yield was slightly improved, although the sintering time was hardly changed (Fig. 7 (a)). Also increased (FIG. 7B). In addition, the shutter strength (SI), which is a management index of cold strength that greatly affects the operation performance of the blast furnace, is improved by 10% or more (Fig. 7 (c)), and the reduction differentiation characteristic (RDI) is improved. Was improved by 8% (Fig. 7 (d)).

In the present invention, a diluted gas is used as the gaseous fuel supplied to the charging bed, but the degree of dilution will be described below. Table 4 shows the lower combustion limit and the upper combustion limit of the blast furnace gas, the coke oven gas and both mixed gases (M gas), propane, methane and natural gas. For example, if a gas having such a combustion limit is directed to a blower without burning in the charging bed, there is a risk of explosion or combustion in the electrostatic precipitator or the like. Therefore, the inventors use gaseous fuel diluted to the limit without the risk, that is, the concentration below the lower combustion limit, as a result of trial and error, and in order to increase the safety, the concentration of the lower limit of the lower combustion concentration is also 75% or less. As a result of using gaseous fuel, many experiments showed that no problem occurred.

For example, as shown in Table 4, the range where the blast furnace gas burns is 40 vol% (that is, does not burn at less than 40 vol%) at room temperature in the air, and the combustion upper limit is 71 vol%. This means that when the content exceeds 71 vol%, the blast furnace gas concentration becomes too high, and even in this case, the gas does not burn again. Hereinafter, the basis of this numerical value is demonstrated based on drawing.

                                  (vol%) Lower combustion limit Combustion upper limit Blast furnace gas 40.0 71 Coke oven gas 5.0 22 Mixed Gas (M Gas) 12.0 42

8 shows an example of a method for obtaining the combustion limit of blast furnace gas. The ratio of the combustion component (combustible gas) and other (inert: inert gas) contained in the blast furnace gas in the figure is as follows when the combination of H ₂ and CO ₂ and CO and N ₂ is examined.

(1) The ratio of (inert gas) / (flammable gas) for the combination of "H ₂ and CO _2" section was 3.5 / 20.0 = 5.7.

Thus, H ₂ intersects with the axis of 5.7 on the horizontal axis indicating the ratio of (inert gas) / (combustible gas) in this combustion limit diagram. + CO ₂ The intersection portion (combustion limit) of the curve was obtained. The lower limit is 32 vol% and the upper limit is 64 vol%. Ie H ₂ + The lower limit of the combustion limit of CO ₂ is 32 vol% and the upper limit is 64 vol%.

(2) On the other hand, since the ratio of (inert gas) / (combustible gas) in the case of the combination of "CO and N ₂ " which are the remaining combustion components is 53.5 / 23.0 = 2.3, the horizontal axis is similarly performed from the same drawing. The lower limit: 44 vol% and the upper limit: 74 vol% are determined from the point where 2.3 and the curve of CO + N ₂ intersect. Therefore, the lower limit of the combustion limit in this case is 44 vol% and the upper limit is 74 vol%.

In addition, the lower limit of the combustion of blast furnace gas containing both combustion components can be calculated | required by the following formula.

Lower combustion limit = 100 / (23.5 / 32 + 76.5 / 44) ≒ 40%

In addition, if the upper limit of said (1) and (2) is applied in the same formula, a combustion upper limit is calculated | required. In this way, the lower combustion limit and the upper combustion limit of the blast furnace gas can be obtained.

In addition, another reason for noting the lower limit of combustion of gas fuel in the present invention is explained as follows. Fig. 9 shows the relationship between the combustion component (combustion gas) concentration and the temperature of gaseous fuel at ambient temperature in the atmosphere (see Corona Co., Ltd. Combustion Manual). However, although the combustion limit is obtained as described above, the combustion limit has a temperature dependence. In one example, even if the lower limit of combustion at room temperature (corresponding to the combustion gas concentration in the drawing) is approximately 40 vol%, the range is 200 ° C. It is known to change from 26 to 27 vol%, and to burn at several percent in the region of 1000 캜 and less than 1 vol% in the region of 1200 캜.

From this, the concentration of the gaseous fuel (content of the combustion component) supplied to the charging layer is safe to dilute and supply to a safe area which is lower than the lower limit of combustion at normal temperature, and the thickness in the charging layer is adjusted if only the concentration of the diluted gas is adjusted. It was found that the degree of freedom of combustion position adjustment in the direction (temperature distribution) also increased.

The combustion of gaseous fuel is thus temperature dependent. For example, the combustion range becomes wider as the ambient temperature becomes higher, and it burns well in the temperature field near the combustion application zone of the sinter, but is located downstream of the combustor. It was also found that at a temperature field of about 200 ° C., such as in an electrostatic precipitator, combustion did not occur at the concentration as shown in the preferred embodiment of the present invention.

By the way, in the production of sintered ore, the gaseous fuel supplied into the charging layer of the sintered raw material is sucked by the wind box under the pallet and is formed by the combustion of the solid fuel (powder coke) in the charging layer. Combustion in high temperature zone. Therefore, under the condition that the supply of gaseous fuel is made constant in the amount of heat input to the charging layer, it is possible to adjust (reduce) the amount of powdered coke in the sintered raw material by adjusting the concentration, the supply amount, and the like of the gaseous fuel. In addition, adjustment of the concentration of gaseous fuel means adjusting the combustion of this gaseous fuel so that it may occur at the anticipated position (concentration area) in a charge bed.

In this sense, the combustion application zone in the charging bed under the prior art is a zone in which only solid fuel (bunch coke) is burned, but in the present invention, in addition to the bunk coke, it is also a zone in which gas fuel is burned together. Therefore, in the present invention, the concentration, supply amount, and other supply conditions of the gaseous fuel are based on the premise that there is a powder of coke as part of the fuel. Preferred adjustment of the reverse holding time becomes possible, resulting in an improvement in the strength of the sintered cake.

In the method of the present invention, another reason for using the diluted gas fuel is to adjust the strength and yield of the sintered cake through the shape adjustment of the sintering and melting zone described above. This is because the role of this dilution gas fuel functions effectively after adjusting how long the sintered cake is kept in the high temperature zone (combustion and melting zone) and to what temperature. In other words, the use of the gaseous fuel means that the hot zone holding time of the sintered raw material is long and the maximum reaching temperature is appropriately adjusted. This adjustment is carried out using the gas fuel diluted and adjusted so that the amount of retardant gas (air or oxygen) in the combustion atmosphere does not cause excessive deficiency in accordance with the amount of solid fuel (powder coke) in the sintered raw material. It means. In this regard, in the prior art, regardless of the amount of solid fuel of the sintered raw material and without blowing up the concentration of the flammable gas, the combustion is poor due to the lack of a retardant gas (oxygen) suitable for the amount of the solid fuel or the amount of the flammable gas. Or, on the contrary, partly overburned, causing uneven strength. That is, the present invention can avoid this problem by adjusting the dilution concentration of the gas fuel.

Next, the influence of the diluted gas fuel diluted and supplied for each type of gas fuel is shown. Fig. 10 shows the conditions and results of a comparative experiment of the sintering method of the present invention using a conventional sintering method (no blowing of gaseous fuel) and a gaseous fuel diluted below the lower combustion limit. Conventional sintering method without diluting gas fuel is an example of the use of 5% powdered coke, and in the example of blowing gaseous dilution according to the present invention, powdered coke is added to make a total calorie constant by injecting diluted gas fuel equivalent to 0.8% of powdered coke. The addition amount shows an example as 4.2 mass%. In all of the diluent gas fuel use cases, improvement in shutter strength, yield, and productivity was observed. In the diluent gas fuel use example, the reason why the shutter strength, the yield of the product, etc. is improved is considered to be due to the expansion of the combustion / melt zone represented as the combustion situation, and it is shown that the high temperature zone holding time is prolonged. Could.

11 is a diagram showing the influence of the concentration of blown gas when propane gas and C gas are used as the gas fuel, the concentration of the diluted gas fuel, the shutter strength (a), the yield (b), the sintering time (c), The relationship between the production rate (d) is shown. As is apparent from this figure, in the case of propane gas, when it is used as a diluent gas fuel, an effect is produced at the addition of 0.05 vol% in order to improve the shutter strength, and the yield also shows a similar improvement effect. It is apparent from 0.1 vol% of propane gas, preferably 0.2 vol%, and 0.24 vol% of C gas, preferably 0.5 vol% or more, and 1.0 vol% of clear improvement effect. More than% Therefore, in propane gas, it becomes at least 0.05 vol% or more, Preferably it is 0.1 vol% or more, More preferably, it is 0.2 vol% or more. On the other hand, in the C gas, it is at least 0.24 vol% or more, preferably 0.5 vol% or more, more preferably 1.0 vol% or more, and the upper limit is 75% or less of the lower combustion limit concentration. In the case of propane gas, the effect is saturated with the addition of 0.4 vol%, and the gas concentration at this time corresponds to 25% of the lower combustion limit concentration.

Next, according to the method of the present invention, the cold strength and the reduction differentiation characteristic (RDI) of the sintered ore produced by supplying the gaseous fuel in consideration of the amount of carbonaceous material in the sintered raw material will be described. According to "Mineral Engineering" (Hidei Imai, Takenouchi Sukune, Yoshinori Fujiki, 1976, 175, Asakura Bookstore), the schematic diagram of the sintering reaction is summarized as shown in FIG. In addition, Table 5 shows the tensile strength (cold strength) and the reduction property of various minerals produced in the sintering process. As is apparent from FIG. 12, in the sintering process, a melt starts to form at 1200 ° C., and calcium-ferrite is produced among the constituent minerals of the sintered ore and has a relatively high reducing ability. In addition, when the temperature rises and exceeds about 1380 ° C, it is decomposed into amorphous silicate (calcium silicate) having the lowest cold strength and the reducing property, and secondary hematite which is easy to reduce and differentiate. Accordingly, in order to improve the cold strength of the sintered ore and to improve the RDI, it is a problem whether or not to continuously generate this without decomposing calcium-ferrite.

In addition, according to the description of the publication "Mineral Engineering", the precipitation behavior of secondary hematite, which is the starting point for reduction and differentiation of sintered ore, is explained as shown in FIG. According to the explanation, as a result of the mineral synthesis test, the skeleton crystallin secondary secondary hematite, which is the starting point for reduction differentiation, is Mag. Since it precipitates after heating up to ss + Liq. area and cooling, it is said that reduction differentiation can be suppressed by manufacturing a sintered ore through (2) path instead of (1) path | route on a state diagram. Therefore, in order to manufacture a low RDI sintered or high-strength sintered ore, the heat layer which stored the heat pattern for a long time in the range of 1200 degreeC (calcium-ferrite solidus line temperature) and about 1380 degreeC (transition temperature) is charged. It is important to realize it within. Therefore, it turns out that the charging layer maximum reaching temperature which adjusts the amount of carbon material to add by supply of gaseous fuel is more than 1200 degreeC and less than 1380 degreeC, and it is preferable to set it as the range of 1205 degreeC-1350 degreeC.

Next, the inventors used a vertical tubular test port with a transparent quartz window to know the relationship between the width of the combustion zone and the dilution fuel gas, and the propane gas diluted with the exhaust gas of the sinter cooler was placed on top of this port. From the charge layer of the sintered raw material was carried out. The sintered raw material used in this experiment is a general one used by the applicant company, and the suction pressure was set at 1200 mmH ₂ O. In this experiment, the concentrations of blown propane were diluted to 0.5 vol% and 2.5 vol%. In addition, in terms of calorific value, it is approximately equivalent to 1 mass% of powdered coke with 0.5 vol% blowing of propane gas.

14 is a photograph showing an observation result of a combustion zone at the time of propane gas blowing in this experiment. As shown in this figure, the propane gas diluted to 2.5 vol% of concentration burned on the raw material loading layer immediately after blowing, and gaseous fuel did not enter the charging layer, and there was no effect. On the other hand, when the dilution degree of propane gas was 0.5 vol% with respect to air, it did not burn in the upper part of a charge layer, but entered into the said charge layer and burned rapidly in the said charge layer. As a result, the upper and lower widths of the combustion zone when sintered under atmospheric conditions were about 70 mm, while the width of the combustion zone (ie, equivalent to the high temperature zone holding time) was 2 when the diluted propane gas was blown. Expanded more than twice.

Therefore, it was found that the effect of increasing the thickness of the combustion zone was also expressed at a concentration of 0.5 vol%, which is 1/5 of the propane lower limit of combustion concentration of 2.5 vol% (theoretical value, large air). On the contrary, in the gas fuel blowing technique according to the present invention, it was also found that it is difficult to control combustion in the charging layer unless the gas fuel is diluted.

In addition, in this experiment, the fall speed of the combustion zone (this reciprocal water is maintained in the high temperature zone holding time) was also examined. As a result, when the coke was merely increased or when hot air was blown, the fall speed was greatly decreased. Although productivity decreased, when the diluted gas fuel was used, since the combustion speed became drastically faster than the use example of solid fuel, the descent rate of the combustion zone showed little difference from the case of atmospheric sintering.

Next, the inventors investigated the influence of the blowing position of the diluted gas fuel.

The specifications of this experiment are shown in Table 6. Experiment No. 1 is the base condition of the present condition of coke: 5mass% blending in sintered raw materials, and Experiment No. 2 reduces the powdered coke ratio by 1 mass% to 4 mass%, and instead, 0.5 vol% of propane gas was blown. Heat input constant conditions, Experiment No. 3 is a condition in which powdered coke is mixed with 10 mass%, and Experiment No. 4 is used to test a hot gas at 450 ° C. for the purpose of verifying a difference from a heating furnace (Japanese Patent Publication No. 60-155626). It is a condition to blow.

Test No. No.1 No.2 No.3 No.4 Powdered coke ratio (large raw material, mass%) 5 4 10 5 Propane Concentration (Large Air, vol%) 0 0.5 0 0 Thermal furnace (450 ℃ hot air blowing) OFF OFF OFF ON

Fig. 15 shows the result, which is an example of diluting coke oven gas (C gas) to 2% as a gaseous fuel. This figure shows the result of examining the relationship between the blowing position at the time of blowing in gaseous fuel, the characteristic sintered ore shutter strength, and the yield of a product. The injection position of diluent gas fuel was made into the position of 100-200 mm, the position of 200-300 mm, and the position of 300-400 mm from the loading layer surface. As can be seen from the results shown in this drawing, at the blowing position of 100 to 200 mm, the combustion / melting zone, which appears bright (white) in the drawing, moves to the 100 mm position, and then the diluted gas fuel is supplied from above the test port. And diluting gaseous fuel is burned in a combustion and molten zone while it is located at 100-200 mm. Similarly, at the 200-300 mm position, the diluent gas fuel is supplied from the upper side of the test port from the stage where the combustion / melt reaches the 200 mm position, and the combustion / melt stage is similarly 300 mm at the 300-400 mm position. This is done by supplying diluent gas fuel from the stage where the position is reached. In addition, the combustion / melting zone of each layer position when the dilution gas fuel of the conventional method is not performed is also shown for reference.

In addition, since the supply of combustion air for the test port flows from top to bottom as in the normal sintering operation, when the gas fuel is added, the gas fuel is added and supplied to the combustion air so as to have a predetermined concentration.

As shown in Fig. 15, the combustion and melting zones are bright (white), and remain in the thickness as slightly thicker than the conventional method in the region of 100 to 200 mm. In the 200-300 mm area, the thickness of combustion and melting zones is clearly increased as compared with the conventional method, and the 300-400 mm area also has a clear difference compared with the conventional method.

From the above, it is preferable that the supply of the gas fuel is carried out to the portion of the combustion / melting zone on the pallet of the sintering machine in which the dilution gas fuel blowing effect becomes an area of 200 mm or less from the surface of the charging layer. Can also be reduced. In addition, since the shutter strength of the sintered ore when it is supplied to the area of 200 mm or less significantly increases even if gas fuel is not excessively supplied to the area of less than 200 mm from the charged layer surface, the yield of the characteristic sintered ore can be improved as a whole. have.

Fig. 16 schematically shows the combustion situation of the upper layer portion up to 200 mm and the middle lower layer portion of 200 mm or less from the charged layer surface. Arrow A shown in this figure shows the advancing direction (fuel direction) of sintering, and FIG. 16 (a) shows the combustion position of powdered coke and gaseous fuel in an upper layer part (up to <200 mm). In this case, since the combustion zone formed by the fuel of the powdered coke is originally narrow at the upper part of the charging bed, and the combustion point of the powdered coal of the powdered coke and the combustion point of the gaseous fuel combusted in this combustion zone approach each other, The temperature pattern as described above is obtained. In this temperature distribution, the combustion zone of the powdered coke (solid fuel) is shown as a hatched portion, and the temperature zone of the gaseous fuel combusted thereon is shown as a non-hatched portion. As can be seen from this figure, since the combustion of coke and gaseous fuel occurs at the same time in the upper part of the charging bed (both of them approach each other and burn), the high temperature zone holding time during T ₁ , T ₂ in the figure. (Equivalent to about 1200 ° C) becomes narrow as shown. In other words, the temperature distribution is such that the coke combustion zone represented by the hatched portion is slightly enlarged. This is because it is preferable to perform the supply of the gas fuel to the charging bed after the thickness of the combustion / melting zone becomes 15 mm or more, so that the effect of blowing the gas fuel is low when the original high temperature zone holding time is narrow. To match. On the other hand, Fig. 16 (b) is a case where the gaseous fuel is supplied to the middle layer and the lower layer, and in the middle layer and the lower layer, as the combustion zone moves from the upper layer to the lower side, there is also a rise in the temperature of the charged layer, and the combustion zone expands. It burns at a position farther than the case of 16 (a). As a result, the temperature distribution becomes as shown on the right side of Fig. 16B. That is, since the combustion point of gaseous fuel is far from the solid fuel (coke) combustion point shown by hatching, the synthesized temperature distribution curve becomes a large temperature distribution at the base. Therefore, the high temperature zone holding time based on the combustion of the solid fuel and gaseous fuel represented by T ₃ and T ₄ is extended, and the shutter strength of the sintered ore obtained is improved.

In the case of Fig. 16B, the ignition temperature of the gas fuel for adjusting the high temperature zone holding time is preferably 400 ° C to 800 ° C, more preferably 500 ° C to 700 ° C. The reason is that if the ignition temperature is lower than 400 ° C, it does not lead to the expansion of the high-temperature zone but merely expands the distribution of the low-temperature zone. On the other hand, if the temperature exceeds 800 ° C, it is too close to the high temperature zone holding time due to the combustion of solid fuel. This is because the effect of extending the high temperature zone holding time is small.

Next, an example of a method of adjusting the highest reaching temperature (in-bed temperature) in the charged bed by supplying diluent gas fuel will be described. Fig. 17 schematically shows the state of the layer temperature distribution during sintering. This figure explains the sintering method which concerns on this invention based on addition of 5 mass% of solid fuel (powder coke) in the example of temperature distribution in the conventional sintering method. For example, in the sintering operation by adding 5 mass% of coke, the conventional sintering method is shown by the curve a. In general, it is effective to add the amount of powdered coke in order to extend the high temperature zone holding time. For example, as illustrated, a case in which 10 mass% of powdered coke is added is indicated by the broken line a ', and the high temperature indicated by the layer thickness is shown. The reverse holding time is extended from (0-A) to (0-B), but the maximum temperature also rises from about 1300 ° C to about 1370 ° C to 1380 ° C, making it impossible to obtain a low RDI sintered ore and high strength sintered ore. .

In this regard, in the sintering operation method according to the present invention method, the amount of powdered coke is suppressed to 4.2 mass% and the dilution C gas is blown, so that the maximum reaching temperature can be suppressed to 1270 ° C and the high temperature range is maintained. Since the time is extended to (0-C), the original purpose of manufacturing a low RDI and high strength sintered ore that has not been realized by the conventional method can be sufficiently achieved.

In short, the conventional sintering method has been an operation method that pays attention to either high temperature zone holding time or maximum temperature adjustment. In this regard, the present invention method adjusts the maximum reaching temperature (1205 to 1350 ° C) under the adjustment of the amount of powdered coke (e.g., inhibited to 4.2 mass%), while blowing the diluent gas fuel into the hot zone. It is an operation method to adjust the holding time. In addition, the curve d of FIG. 17 shows an example in which the amount of solid fuel used is reduced to only 4.2 mass%, the maximum reaching temperature is low, and the high temperature zone holding time is short.

Fig. 18 shows an example in which powdered coke 5mass% is used as a conventional sintering method, and shows an example in which a diluted C gas blowing in combination with a powdered coke amount of 4.2 mass% and a concentration of 2.0 vol% is used as a suitable example of the present invention. As can be seen from the thermal rain in this figure, in the conventional method, in order to maintain a high temperature zone holding time, a combustion situation exceeding 1400 ° C occurred. On the other hand, when the amount of powdered coke is stopped at 4.2 mass% and C gas is blown at a concentration of 2 vol%, the 1400 ° C region is lost, and the maximum reaching temperature can be suppressed to 1350 ° C or lower, while maintaining the high temperature zone. The situation has become possible to realize the extension of.

Fig. 19 shows changes over time in the charged bed temperature (a), the exhaust gas temperature (b), the passing air volume (c), and the exhaust gas composition (d) due to the injection of the diluted propane gas under constant heat input conditions. To indicate. Here, the charge layer internal temperature is the value measured with the thermocouple charged in the position of 200 mm (charging layer thickness: 600 mm) height from the grate bar in the said test port. Moreover, it measured at two places of 5 mm from a center part and a wall in the circumferential direction of a test port. From these figures, the time for melting the sintered raw material heated to 1205 ° C or more (hereinafter referred to as "high temperature zone holding time") is increased by injecting diluted propane gas, but the maximum reaching temperature is increased. It was confirmed that it was not done. Moreover, dilution blows propane gas, and the oxygen concentration in exhaust gas falls, and it is estimated that oxygen contributed to the combustion reaction efficiently.

Fig. 20 shows the temperatures (a), (a '), and exhaust gas concentrations (b) and (b') in the charged bed at the time of diluted propane blowing (0.5 vol%) and the increase in coke only (10 mass%). ) Is shown for changes over time. From these figures, when the use ratio of the powdered coke was increased, the high temperature zone holding time of 1200 ° C or more was approximately equivalent to that of blowing the propane gas diluted to a concentration of 0.5 vol%, but the maximum reaching temperature exceeded 1350 ° C. In addition, by increasing the amount of powdered coke, it was confirmed that the concentration of CO ₂ in the exhaust gas was greatly increased from 20 vol% to 25 vol%, the CO concentration was also increased, and the rate at which the coke contributed to combustion was decreasing. .

Fig. 21 summarizes the results of various characteristic tests in these tests. As is clear from this figure, the sintering time is slightly extended by the injection of diluted propane gas, but the yield, shutter strength, and production rate are all improved, and the reducibility (RDI) and the reducing ability are greatly improved. By optimizing the blowing, it was confirmed that the quality of the sintered ore can be improved in addition to the improvement of the production rate and the yield.

On the other hand, when only the powdered coke is increased to 10 mass%, not only the sintering time is prolonged but also the maximum reaching temperature rises more than necessary, so that a lot of amorphous silicates of low strength are produced, and both the shutter strength and the yield are large. Lowered. Moreover, in the case of a 450 degreeC heating furnace, the improvement effect of a shutter intensity and a yield was small, and it corresponded substantially with the result in the conventional commercial equipment.

As can be seen from the above description, when a diluted gaseous fuel is used, this gas burns in the charging bed, causing the combustion zone in the bed to expand, and the heat of combustion by the coke in the sintered raw material and the diluted gas. By the synergistic action of the heat of combustion of propane gas, a wide combustion zone is formed. As a result, the maximum reaching temperature does not rise excessively, while for the high temperature zone holding time, it is extended by the combustion of the supplied diluent gas.

Next, the inventors investigated the effects of the reduced sintered ore on reducing properties, cold strength, and the like by blowing the diluted gas fuel in comparison with the conventional methods (5 mass%, 10 mass% coke, hot air blowing). The measured items are the mineral composition ratio (influence on cold strength and reduction) in the sintered ore, the apparent specific gravity (influence on cold strength), and the pore diameter distribution of 0.5 mm or less (influence on reduction).

First, FIG. 22 shows the results of investigating the composition ratio of the mineral phase in the sintered ore of qualities quantified by the powder X-ray diffraction method. From this figure, when solid fuel and dilute propane gas are used in combination with a calorific value constant (coke 4mass% + propane 0.5vol%), calcium-ferrite is stably produced, which leads to an improvement in the reduction property and an increase in cold strength. It is considered to have caused.

FIG. 23 shows the measurement result of apparent specific gravity of the characteristic sintered ore, and FIG. 24 shows the measurement result of pore diameter distribution of 0.5 mm or less by a mercury porosimetry porosity meter. From Fig. 22, as a result of the heating from the outside of the granulated particles by blowing the diluted propane gas, the melt flow is promoted, and the porosity (apparent specific gravity) of 0.5 mm or more is reduced, which is considered as a factor for improving the cold strength. do. Moreover, from FIG. 24, when dilution propane gas is blown in a fixed calorific value, the heat source in a sintering raw material particle reduces, and the micropore of 500 micrometers or less derived from the ore which affects a blood reducibility easily remains, It is considered that the production of high-reducing sintered ore has become possible.

Fig. 25 shows a schematic diagram of the sintering behavior when only coke is used (a) and when diluent gas fuel is blown in combination. As shown in the figure, in the conventional sintering using only coke, the coke is heated from the inside of pseudo particles by powdered coke combustion, whereas in the combined method of coke + gas fuel according to the present invention, from the outside of pseudo particles by combustion of gas fuel. Since it is heated, it is inferred that micropores in ore tend to remain, and that JIS-RI can also be relatively high at a low rate of RDI.

Fig. 26 shows a schematic diagram of the pore structure of the sintered ore at the time of blowing the diluted gas fuel. As shown in this figure, the improvement of the productivity of sintered ore promotes the coalescence of 0.5-5 mm pores affecting the yield and cold strength, reduces the number, and reduces the proportion of pores of 5 mm or more that affects air permeability. It is available to increase. In addition, it can be seen that it is preferable to have a pore structure in which a large number of fine pores of 0.5 mm or less existing in iron ore remain in order to improve the reduction of sintered ore. In this respect, according to the present invention, it is considered that by diluting the gaseous fuel injection, it is possible to approximate the pore structure of the ideal sintered ore.

FIG. 27 shows the results of a test for identifying a limit coke ratio (limit coke ratio, which is equivalent to 73% of the maximum value when no propane gas with diluted shutter strength) can be maintained to maintain the required cold strength. As shown in this figure, the coke ratio for obtaining the same cold strength (shutter strength 73%) as in the current state by diluting propane gas blowing (concentration 0.5vol%) is as shown in Fig. 27A, It can be reduced (about 20kg / t) from 5mass% to 3mass%. As shown in Figs. 27B and 27C, the coke ratio is apparently lowered from 5 mass% to 3.5 mass%, respectively, in order to obtain 73% yield and 1.86 production yield.

As is apparent from the above description, the present invention selects the appropriately diluted gaseous fuel according to the amount of charcoal while the combustion / melt moves from the surface layer of the charging layer to the lower layer as the pallet progresses. By supplying, the effect | action which expands the function of the combustion and molten zone in a charge layer can be produced, and the improvement of sintered ore quality and productivity can be aimed at.

Example

(1) Example 1 Coke oven gas (C gas) was used as the gas fuel (1-2. 5 vol%) diluted using the test port shown in FIG. 6, and the amount of carbonaceous material (coke) in the raw material was 5 mass%. A sintering pot test was performed. Other conditions were made the same as the above-mentioned experimental conditions. The result is shown in FIG. As shown in this figure, when using the C gas diluted in accordance with the present invention, increasing the concentration of the C gas significantly increases the combustion width, and improves the yield and production rate. It was also found that it can be improved.

(2) Example 2: The test was carried out under the same conditions as in Example 1. The result is shown in FIG. As shown in this figure, when using propane gas (0.02 to 0.5 vol%) diluted in accordance with the present invention, when the concentration of the C gas is increased, the combustion zone is significantly expanded, and the yield and production rate are improved. At the same time, it was found that the cold strength (SI) could also be improved.

(3) Example 3: This example uses the test port shown in FIG. 6, and the coke oven gas (C gas) diluted with the cooler exhaust gas from the upper side of this port compared with the example without dilution gas injection. It is an example which inject | poured the sintering raw material (containing 20 mass% of return fine) shown in Table 7 in a charge layer.

In this embodiment, the sintered layer contains 4.8 to 5.0 mass% (external water) of powdered coke, and according to the present invention, the C gas with a concentration of 1.0 to 2.0 vol% (large air) is sucked. It is the example which blown into the position of 100-400 mm (total thickness 600mm, car-beam thickness laminated 200 mm in the lowest layer) on the charge layer surface on the conditions of pressure 1200mmAq (differential pressure 1000Aq). In addition, when the insertion position is 80 m in total length of the DL sintering machine, and this is applied to the total height of 600 mm, the insertion position of 100 to 200 mm of test No. 2 is 80 (m) x 100 to 200/600 ( Mm) corresponds to an example in which a 13.3 m long dilution gas blowing hood 12 is installed at a position of 13.3 to 26.6 m. Therefore, in the example of the injection position of 200-300 mm of test No. 2, the diluent gas blowing hood 12 of length 13.3m was also installed in the position of about 26.7-39.7 mm behind the ignition furnace on a sintering machine pallet, and the gas This is equivalent to the case of blowing.

Table 8 shows the results of these examples (No. 1 to No. 7). As can be seen from this result, the cold strength (SI strength) and the yield of the sintered ore are both higher than Nos. 1 to 7, which show a suitable example of the present invention, compared to No. 1 serving as a comparative example, and It can be seen that the improvement is remarkable in the example (No. 3, 4, 6, 7) in which the insertion position comes to the middle end of the charging layer. In addition, it was found that the production rate was increased by adjusting the blowing gas concentration to 1 vol% under a constant coke amount (4.8 mass%) rather than lowering the coke amount and increasing the concentration of the blowing gas amount. In addition, it was found that the blowing method in which both the reduction rate (RI) and the reduction differentiation rate (RDI) affect the intermediate end of the charging layer having a blowing position of 200 to 300 mm is most effective with respect to the quality of the sintered ore.

(4) Example 4 This example illustrates an example in which the method for producing a sintered ore according to the present invention is applied to a DL-type sintering machine having a scale of 10,000 tonnes of monoacid. The length of the used DL sintering machine is 90 m from the ignition furnace to the light distribution section. At a position of about 30 m behind the sintering furnace of this sintering machine, a gas blowing hood having a length (pallet moving direction) of 15 m and a size covering the entire detonation was provided, and coke oven gas (C gas) was used as the gas fuel. Particularly, combustion that proceeded from the surface layer in the charging layer thickness direction to equivalent to 200 mm under the conditions of the charging layer layer thickness of 600 mm (excluding the round steel thickness of 200 mm) without targeting the upper layer portion of the charging layer of the raw material of the sintering machine. The C gas supplied with the dilution with air of normal temperature and the density | concentration of 2 vol% was supplied in the position corresponded to 300 mm from the position where a melting zone exists. The blown C gas reached the above position through the sintered bed by adjusting the suction pressure of the wind box below the sintering machine pallet, and was allowed to burn at the combustion / melting zone. In addition, the inside of the gas blowing hood was made to be slightly positive pressure by atmospheric pressure, and was balanced with the suction negative pressure of the wind box. At this time, the amount of C gas used was 3000 m 3 (standard state) / h.

As a result of the operation of the sintering machine, the tumbler strength was improved by about 3% as a whole, the RDI was also improved by about 3% from the level of normal operation, and the RI was improved by about 4% from the normal operation. In addition, the production rate increased by 0.03 t / hr · m 2.

As described above, according to the present invention, in the operation of the lower suction type sintering machine, it is possible to burn at a target position in the charging layer by using diluted gas fuel from the upper side of the charging layer, and in this case, By adjusting the feed position of the diluted gas fuel, the maximum reaching temperature during combustion, and the high temperature zone holding time, not only the upper part of the charging layer which is liable to become insufficient in combustion and lowers the cold strength of the sintered ore, but also below the middle layer of the charging layer. Operation such as raising the sintered ore strength of any part can be performed. In addition, in the present invention, without deteriorating the air permeability of the entire charging layer, in particular, the reaction in the combustion and melting zone, for example, by adjusting the width in the vertical direction and the width in the pallet moving direction of this zone, Since the intensity | strength of the sintered cake in the position of can be adjusted, the characteristic sintered ore with high cold strength as a whole sintered ore can be manufactured by ensuring a high yield and high productivity. And using the sintering machine of this invention, operation of such a sintering machine can be performed stably.

Claims (31)

A charging step of charging a sintered raw material including spectroscopic stones and carbonaceous material on a pallet which is circulating and forming a charging layer containing carbonaceous material on the pallet; An ignition process for igniting carbon material on the surface of a charging layer in an ignition furnace; A firing process that draws air through a windbox disposed under the pallet, burns the carbonaceous material in the charging layer, and generates a sintered cake by the heat of combustion generated; And a gas fuel combustion step of supplying a gas fuel diluted to a lower combustion lower concentration from above the charging layer and burning the gas fuel in the charging layer. The method of claim 1, The gas fuel combustion process supplies gaseous fuel diluted below the lower combustion limit concentration from above the charging bed and burns the gaseous fuel in the charging bed, and also achieves the highest reaching temperature in the charging bed or the high temperature zone holding time in the charging bed, Or adjusting the maximum reaching temperature and the high temperature zone holding time in the charging layer. The method of claim 2, The gas fuel combustion process is characterized in that the gas fuel diluted to below the lower combustion limit concentration is supplied from above the charging bed, and the gas fuel is burned in the charging bed, and the maximum reaching temperature in the charging bed is adjusted. Method for producing sintered ore. The method of claim 3, wherein The gas fuel combustion process supplies the gaseous fuel diluted below the lower combustion limit concentration from above the charging layer, burns the gaseous fuel in the charging layer, and adjusts the amount of carbonaceous material in the sintered raw material. A method for producing a sintered ore, comprising adjusting the attained temperature. The method of claim 4, wherein The gas fuel combustion process supplies the gas fuel diluted below the lower combustion limit concentration from above the charging layer, burns the gas fuel in the charging layer, and adjusts the amount of carbonaceous material in the sintered raw material. The method for producing a sintered ore comprising adjusting the temperature to 1205 占 폚 to 1350 占 폚. The method of claim 3, wherein The gas fuel combustion process supplies the gas fuel diluted to the lower combustion lower concentration from above the charging layer, burns the gas fuel in the charging layer, and adjusts the supply amount of the gas fuel to set the maximum reaching temperature to 1205. A method for producing a sintered ore, comprising adjusting the temperature to 1 ° C to 1350 ° C. The method of claim 3, wherein In the gas fuel combustion process, the gas fuel diluted to the lower combustion lower concentration is supplied from above the charging layer, and the gas fuel is combusted in the charging layer, and the amount of carbonaceous material in the sintered raw material and the gas fuel supply amount are adjusted. By adjusting the maximum reaching temperature to 1205 占 폚 to 1350 占 폚. The method of claim 2, The gas fuel combustion process is characterized in that the gas fuel diluted to below the lower combustion limit concentration is supplied from above the charging layer, and the gas fuel is burned in the charging layer, and the high temperature zone holding time in the charging layer is adjusted. The manufacturing method of the sintered ore to make. The method of claim 8, The gas fuel combustion process supplies a gas fuel diluted below the lower combustion limit concentration from above the charging layer, burns the gas fuel in the charging layer, and adjusts the concentration of the gas fuel in accordance with the amount of carbonaceous material in the sintered raw material. And adjusting the holding time of the high temperature region in the charged layer. The method of claim 1, The gas fuel combustion process supplies gaseous fuel diluted below the lower combustion limit concentration from above the charging bed, and burns and melts the gaseous fuel diluted below the lower combustion limit concentration with at least a part of it unburned. A method of producing a sintered ore, characterized by comprising the combustion to reach to. The method of claim 1, The gas fuel combustion process is characterized in that the production of sintered ore characterized in that the gas fuel diluted to below the lower combustion limit concentration is supplied from above the charging layer, the gas fuel is burned in the charging layer and the shape of the combustion / melting zone is adjusted. Way. The method of claim 11, The adjustment of the shape of the combustion and melting zone is to adjust the thickness in the height direction of the zone and / or the width in the pallet movement direction. The method of claim 1, The gas fuel combustion process supplies the gas fuel diluted below the lower combustion limit concentration from above the charging layer, burns the gas fuel in the charging layer, and extends the high temperature zone holding time of the combustion and melting zone to increase the cold strength of the sintered ore. The manufacturing method of the sintered ore characterized by adjusting. The method of claim 1, The gas fuel combustion process consists of supplying a gas fuel diluted below the lower combustion limit concentration from above the charging layer, burning the gas fuel in the charging layer, and adjusting the supply position of the gas fuel to the charging layer. Method for producing a sintered ore, characterized in that. The method of claim 1, The gas fuel combustion process is a method for producing a sintered ore characterized in that the gas fuel diluted to a lower combustion lower concentration at a position after the ignition furnace is supplied from above the charging layer, and the gas fuel is combusted in the charging layer. . The method of claim 1, The gas fuel combustion process is to supply gaseous fuel diluted below the lower combustion lower concentration level between the generation of the sintered cake at the surface layer portion of the charging layer and the completion of sintering, and to burn the gas fuel in the charging layer. The manufacturing method of the sintered ore characterized by the above-mentioned. The method of claim 1, In the gas fuel combustion process, a sintered ore is formed by supplying a gas fuel diluted to a lower combustion lower concentration in a region where the thickness of a combustion / melting zone becomes 15 mm or more and burning the gas fuel in a charging layer. Manufacturing method. The method of claim 1, The gas fuel combustion process is characterized by supplying a gas fuel diluted below the lower combustion limit concentration after the position where the combustion wire reaches 100 mm below the surface layer, and combusting the gas fuel in the charging layer. Method for producing sintered ore. The method of claim 1, The gas fuel combustion process is a method for producing a sintered ore, characterized in that the gas fuel diluted to the lower combustion lower concentration near the sidewalls of the charging layer is supplied, and the gas fuel is combusted in the charging layer. The method of claim 1, The gas fuel combustion process consists of supplying a gas fuel diluted to a lower combustion lower concentration from above the charging layer in the sintering machine length direction, burning the gas fuel in the sintering layer, and adjusting the cold strength of the sintered ore. A method for producing a sintered ore, characterized in that. The method of claim 1, The gaseous fuel is a method of producing a sintered ore, characterized in that the flammable gas diluted to a concentration of less than 75% and less than 2% of the lower combustion limit. The method of claim 10, The gaseous fuel is a method of producing a sintered ore, characterized in that the flammable gas diluted to a concentration of less than 60% of the lower limit of combustion and more than 2%. The method of claim 11, The gaseous fuel is a method of producing a sintered ore, characterized in that the flammable gas diluted to a concentration of 25% or less of the lower combustion limit concentration and 2% or more. The method of claim 1, The gaseous fuel is at least one gas selected from the group consisting of blast furnace gas, coke oven gas, blast furnace-coke oven mixed gas, propane gas, natural gas and methane gas. In a sintering machine having a pallet for circulation, a suction wind box disposed below the pallet, a raw material supply device for supplying sintered raw material onto the pallet, and an ignition furnace for igniting carbon material in the sintered raw material, And a gaseous fuel supply device for discharging the gaseous fuel diluted in the concentration below the lower combustion limit from above the charging bed into the charging bed on the downstream side of the ignition furnace. The method of claim 24, And at least one gaseous fuel supply device is disposed in the length direction of the sintering machine downstream of the ignition furnace. The method of claim 24, And the gas fuel supplying device is disposed at a position between sintering and completion at the stage where the combustion wire proceeds below the surface layer in the pallet traveling direction. The method of claim 24, The gas fuel supply apparatus is disposed in the vicinity of the side wall sintering apparatus. The method of claim 24, The gas fuel supply apparatus is characterized in that for supplying a flammable gas of 75% or less of the lower combustion limit concentration and diluted to a concentration of 2% or more. The method of claim 29, The gas fuel supply device is characterized in that for supplying a flammable gas of 60% or less of the lower combustion limit concentration and diluted to a concentration of 2% or more. The method of claim 30, The gas fuel supply apparatus is characterized in that for supplying a combustible gas diluted to a concentration of less than 25% and less than 2% of the lower combustion limit concentration.

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