JP7553759B2 - Sintering machine, sintering machine operation method - Google Patents

Description

The present invention relates to a sintering machine and a method for operating the sintering machine.

Various methods for adding raw materials to the surface of the sintered layer and technologies for using biomass have been studied for the production of sintered ore.

For example, Patent Document 1 discloses a method for producing sintered ore having excellent reducibility and resistance to reduction disintegration, which is characterized by blending raw materials so that the total _SiO2 content is 4.8% by weight or less, and mixing pulverized fuel having a free carbon content of 50.0% by weight or more and a particle size of 1.0 mm or less into the gas sucked from the surface of the sintering bed after ignition is completed, and sintering the mixture.

Patent Document 2 also discloses a method for reducing nitrogen oxides in a sintering machine, which is characterized by including a step of spraying solid fuel or solid fuel mixed with liquid fuel on the surface of an ignited sintering raw material layer during the process of sintering iron ore using a sintering machine.

Patent Document 3 also discloses a "method for producing sintered ore, which supplies diluted gaseous fuel to the sintered layer, thereby producing high-strength sintered ore with a high yield."

In addition, Patent Document 4 describes a method for producing sintered ore, in which pseudo-particles obtained by granulating sintered raw materials consisting of iron ore, auxiliary raw materials, return ore, and solid carbonaceous material are segregated and charged into the pallet of a sintering machine, and a carbon concentration difference is generated in the height direction of the raw material layer, and then the sintered ore is fired.
When oil palm kernel shell charcoal, which is a solid carbide produced by heat-treating oil palm kernel shell, is blended as a part or all of the solid carbonaceous material in the sintering raw material,
"A method for producing sintered ore, characterized in that it contains oil palm kernel shell charcoal with an average particle size adjusted to 2.7 mm to 6.0 mm."

Japanese Patent Application Publication No. 03-079730 Japanese Unexamined Patent Publication No. 51-80608 JP 2011-252207 A JP 2014-218713 A

Here, the conventional methods for producing sintered ore using a sintering machine have problems with productivity and environmental impact. Specifically, they are as follows:

First, in the technology of adding carbonaceous materials (coke, coal), liquid fuel, etc. onto the sintering raw material layer after ignition (Patent Documents 1 and 2, etc.), the combustibility of the carbonaceous materials and liquid fuel is low, and the combustion efficiency of the surface layer of the sintering raw material layer is poor. Therefore, there is a problem that the quality of the sintered ore in the upper layer of the sintering layer (the upper layer obtained by dividing the sintering raw material layer into two equal parts, top and bottom), which is sintered, is low, and the yield is also low.
To address this issue, a technique for improving the yield of sintered ore near the upper layer of the sintered layer is known (Patent Document 3, etc.), in which gaseous fuel is made to flow through the sintered raw material layer after ignition, and the temperature near the surface layer of the sintered raw material layer is increased by the combustion heat. However, the cost of gaseous fuel is high, and the associated equipment is also expensive.

On the other hand, in the production of sintered ore, _CO2 emissions account for about 10% of the entire steelmaking process, and _NOx emissions account for about 35%. Therefore, there is a need to reduce _CO2 and _NOx emissions.

There is no particular mention of these issues in the above-mentioned Patent Documents 1 to 3. As another prior art, biomass fuels, such as woody biomass fuels, are derived from plants, and the _CO2 generated during sintering is carbon neutral, so attempts have been made to use them in the sintering process (Patent Document 4, etc.).
However, conventional biomass fuels are used as a substitute for coke, which reduces the yield of sintered ore.

In addition, conventional biomass fuels are used as a substitute for coke and therefore require prior carbonization, which not only increases costs but also causes volatile matter to evaporate during the carbonization process, making it impossible to effectively use the fuel in the sintering process.
When biomass fuel is used without carbonization, the hydrocarbon gas generated by pyrolysis of the biomass fuel during the temperature rise in the sintering raw material layer is mixed into the exhaust gas, which adversely affects the operation of the electrostatic precipitator of the sintering machine (specifically, the electrodes are damaged, shortening the equipment life), and also increases the particulate matter content, which increases the maintenance cost of the sintering machine.

The objective of the present invention is to provide a sintering machine and a method of operating the sintering machine that utilizes biomass fuel, is low-cost, can reduce NOx emissions, and improves the yield of the upper layer of the sintered layer.

The means for solving the problems include the following aspects.
[1]
A sintering pallet group in which a plurality of sintering pallets are connected together;
A raw material supplying device for supplying raw material for sintering into the sintering pallet;
an ignition furnace that ignites a surface portion of the layer of the sintering raw material supplied into the sintering pallet with a flame;
A fuel supply device is provided on the discharge side of the ignition furnace and supplies biomass fuel onto the layer of the sintering raw material;
A sintering machine comprising:
[2]
The sintering machine according to [1], wherein the fuel supplying device is a device that supplies the biomass fuel at a calorific value per unit area of 23.3 to 372.0 MJ/ ^m2 onto the layer of the sintering raw material.
[3]
The sintering machine according to [1] or [2], wherein the fuel supply device is a device that supplies the biomass fuel onto the layer of sintering raw material within 60 seconds immediately after the ignition of the surface layer of the layer of sintering raw material is completed by the ignition furnace.
[4]
The sintering machine according to any one of [1] to [3], further comprising a fire prevention device that prevents the flame of the ignition furnace from contacting the biomass fuel supplied on the layer of sintering raw material.
[5]
a raw material supplying step of supplying a sintering raw material into a sintering pallet in a sintering pallet group in which a plurality of sintering pallets are connected to each other;
Ignite the surface layer of the layer of the sintering raw material supplied into the sintering pallet with a flame of an ignition furnace;
A fuel supplying step of supplying biomass fuel onto the layer of the sintering raw material on the discharge side of the ignition furnace;
The method for operating a sintering machine comprises the steps of:
[6]
The method for operating a sintering machine according to [5], wherein in the fuel supplying step, the biomass fuel is supplied onto the layer of the sintering raw material in an amount of 23.3 to 372.0 MJ/ ^m2 in terms of heat per unit area.
[7]
The method for operating a sintering machine according to [5] or [6], wherein in the fuel supplying step, the biomass fuel is supplied onto the layer of sintering raw material within 60 seconds immediately after the ignition of the surface layer of the layer of sintering raw material is completed by the ignition furnace.
[8]
The method for operating a sintering machine according to any one of [5] to [7], wherein a fire prevention device is used to prevent the flame of an ignition furnace from coming into contact with the biomass fuel supplied onto the layer of sintering raw material.

The present invention provides a sintering machine and a method for operating the sintering machine that utilizes biomass fuel and improves the yield of the upper layer of the sintered layer at low cost.

FIG. 1 is a schematic diagram showing an example of a sintering machine of the present invention. FIG. 2 is a schematic diagram showing a test device used in the examples. 1 is a graph showing a change in exhaust gas composition during a sintering reaction (ignition time 60 s) in Comparative Example 1. 1 is a graph showing a change in exhaust gas composition during a sintering reaction (ignition time 90 s) in Comparative Example 2. 1 is a graph showing a change in exhaust gas composition during a sintering reaction in Example 1 (ignition time 60 s + sawdust input).

The present invention will now be described.
In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.
In numerical ranges described in stages, the upper limit or lower limit value described in a certain numerical range may be replaced with the upper limit or lower limit value of another numerical range described in stages.
In a numerical range, the upper limit or lower limit described in a certain numerical range may be replaced with a value shown in the examples.
The term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.
A "combination of preferred aspects" is a more preferred aspect.

The sintering machine of the present invention is
A sintering pallet group in which a plurality of sintering pallets are connected together;
A raw material supplying device that supplies raw material for sintering into the sintering pallet;
an ignition furnace for igniting a surface layer of the layer of sintering raw material supplied into the sintering pallet with a flame;
A fuel supply device is provided on the discharge side of the ignition furnace and supplies biomass fuel onto the layer of sintering raw materials;
Equipped with.

On the other hand, the manufacturing method of the sintering machine of the present invention is as follows:
a raw material supplying step of supplying a sintering raw material into a sintering pallet in a sintering pallet group in which a plurality of sintering pallets are connected to each other;
Ignite the surface of the layer of sintering raw material supplied into the sintering pallet with a flame from an ignition furnace;
A fuel supplying step of supplying biomass fuel onto the layer of sintering raw material on the discharge side of the ignition furnace;
has.

The sintering machine and its operating method of the present invention use biomass fuel and can improve the yield of the upper layer of the sintered layer at low cost. The reason for this is presumed to be as follows.

In the gasification reaction of biomass fuel, the combustion and gasification of the biomass fuel proceeds against the air flow due to radiant heat. Furthermore, biomass fuel has a high combustion speed.
Therefore, when the biomass fuel is supplied onto the sintering raw material layer after the surface portion of the sintering raw material layer is ignited, the biomass fuel spontaneously burns due to the sensible heat of the ignited sintering raw material layer, thereby supplying heat to the surface layer of the sintering raw material layer.
Since biomass fuel has high combustibility and a high combustion speed, it efficiently raises the temperature of the surface layer of the sintering raw material layer, thereby increasing the combustion efficiency of the surface layer of the sintering raw material layer and improving the quality of the sintered ore in the upper layer of the sintering layer.

In addition, because biomass fuel has a high combustion rate, unburned gases such as hydrocarbon gas and CO tend to remain in the exhaust gas. However, because biomass fuel is burned on the sintering raw material layer, the generated unburned gas is decomposed and burned by the combustion of carbonaceous materials when it passes through the inside of the sintering raw material layer, and is removed. This reduces the impact on the operation of the sintering machine's electric dust collector, reduces the particulate matter content, and reduces the maintenance costs of the sintering machine.

In addition, the unburned gas generated during the combustion of biomass fuel is decomposed and burned by the combustion of carbonaceous materials inside the sintering raw material layer and removed, so the oxidation potential of the air flowing into the sintering raw material layer is reduced. As a result, in addition to reducing _CO2 by using biomass fuel, the generation of _NOx associated with the combustion of carbonaceous materials inside the sintering raw material layer is suppressed, and _NOx reduction is also achieved.

From the above, it is presumed that the sintering machine and its operating method of the present invention utilize biomass fuel, can reduce NOx emissions at low cost, and can improve the yield of the upper layer of the sintering layer (the upper layer obtained by dividing the sintering raw material layer into two equal parts, top and bottom).
In addition, the sintering machine and its operating method of the present invention can reduce the amount of carbonaceous material in the sintering raw material by the calorific value of the biomass fuel supplied, which makes it possible to reduce _CO2 emissions by the amount of carbonaceous material reduced.

The sintering machine and its operating method of the present invention will be described in more detail below with reference to the drawings.

As shown in FIG. 1, the sintering machine 101 includes, for example, a group of sintering pallets 10, a floor supply device 20, a raw material supply device 30, an ignition furnace 40, a fuel supply device 50, a fire prevention device 60, a grinding and sizing device 70, and an exhaust gas device 80.

(Sintered pallets)
The sintering pallet group 10 includes, for example, a plurality of sintering pallets 11. The plurality of sintering pallets 11 are, for example, endlessly connected.
The multiple sintering pallets 11, which are endlessly connected, are rotated by a driving device (not shown).

(Bedding supply device)
The bedding supply device 20 has, for example, a bedding hopper 21 in which bedding ore (return ore) is charged.
In the bedding supply device 20, bedding ore (return ore) is supplied from a bedding hopper 21 into the sintering pallet 11. As a result, a bedding ore (return ore) layer (not shown) is laid inside the rotating sintering pallet 11.

(Raw material supply device)
The raw material supply device 30 has, for example, a surge hopper 31 into which the sintering raw material 1 is charged, and a feeder 32 that supplies the sintering raw material 1 from the surge hopper 31 into the sintering pallet 11 .

The raw material supply device 30 has hoppers (not shown) for respectively charging raw materials such as iron-containing raw materials, auxiliary raw materials, carbonaceous materials, and return ore, and a mixer for mixing the raw materials discharged from each hopper. The mixture mixed in the mixer is then charged into the surge hopper 31 as the sintering raw material.

In the raw material supply device 30, the sinter raw material 1 loaded into the surge hopper 31 is cut out by the feeder 32 and fed into the sintering pallet 11 via a chute (not shown) or the like. This forms a sinter raw material layer 2 on the bedding ore (return ore) layer (not shown) inside the rotating sintering pallet 11.

Here, the sintering raw material 1 includes, for example, an iron-containing raw material, an auxiliary raw material, a carbonaceous material, and return ore. If necessary, the sintering raw material 1 also includes moisture.
The iron-containing raw material is mainly composed of iron ore (sintered ore fines). In addition to iron ore, the iron-containing raw material further includes miscellaneous raw materials such as ironmaking dust (blast furnace dust, sintered dust, steelmaking dust, etc.) and scale. Note that "mainly composed of iron ore (sintered ore fines)" means that 50% by mass or more of the total iron-containing raw material is iron ore (sintered ore fines).
The auxiliary raw materials include CaO-containing raw materials, MgO-containing raw materials, _SiO2 -containing raw materials, etc. For example, the CaO-containing raw materials include limestone, quicklime, slaked lime, dolomite, converter slag, etc.
The carbonaceous materials include coke and anthracite.
Return ore is sintered ore having a particle size that does not meet the lower limit of the particle size of the blast furnace product, and is returned from the sintering process or the blast furnace process.

(Ignition furnace)
The ignition furnace 40 has a furnace body 41 and a burner 42 that emits a flame.
In the ignition furnace 40, the surface layer of the sintering raw material layer 2 supplied into the sintering pallet 11 is ignited by the flame of the burner 42. Specifically, the carbonaceous material in the surface layer of the sintering raw material layer 2 is ignited by the flame. After ignition, the carbonaceous material in the sintering raw material layer 2 burns while the exhaust gas device 80 sucks air from above to below the sintering raw material layer 2. As a result, the sintering raw material layer 2 is sintered sequentially from the upper layer to the lower layer by the combustion heat of the carbonaceous material, and becomes the sintered layer 3.
The phrase "igniting the surface portion of the sintering raw material layer 2 with a flame" refers to applying a flame to the surface of the sintering raw material layer 2.

(Fuel supply device)
The fuel supply device 50 is a device that supplies the biomass fuel 4 onto the sintering raw material layer 2, for example, on the ore discharge side of the ignition furnace 40 (i.e., downstream of the ignition furnace 40 in the conveying direction of the sintering pallet 11).
The fuel supply device 50 has a surge hopper 51 into which the biomass fuel 4 is charged, and a feeder 52 that supplies the biomass fuel 4 from the surge hopper 51 onto the sintering raw material layer 2 .
The fuel supply system of the fuel supply device 50 is not limited to the above, and any other known system such as a belt conveyor system, a slip stick conveyor system, or an apron conveyor system may be used.

The fuel supply device 50 forms a layer of biomass fuel 4 (not shown) on the sintered raw material layer 2 after ignition. The layer of biomass fuel 4 spontaneously burns due to the sensible heat of the ignited sintered raw material layer 2. This combustion supplies heat to the surface layer of the sintered raw material layer 2, efficiently raising the temperature of the surface layer of the sintered raw material layer 2 and extending the time during which the surface layer is kept at a high temperature. This increases the combustion efficiency of the surface layer of the sintered raw material layer 2 and improves the quality of the sintered ore in the surface layer of the sintered layer 3. Note that if the biomass fuel 4 is put onto the sintered raw material layer 2 before the sintered raw material layer 2 is ignited, the biomass fuel 4 will complete combustion during ignition in the ignition furnace 40, and the time during which the surface layer of the sintered layer 3 is kept at a high temperature will not be extended, and the above-mentioned effect will not be obtained.

Here, examples of biomass fuel include sawdust, shavings, bark, wood chips, wood pellets, and the like.
As the biomass fuel, products obtained by subjecting sawdust, shavings, bark, wood chips, wood pellets, etc. to drying and pulverization (with a shredder, etc.) may be used.
The biomass fuel may be fuel produced by crushing wood (trees, logs, boards, etc.) before being supplied onto the sintering raw material layer 2.

In the fuel supply device 50 (i.e., the fuel supply process), from the viewpoint of improving the sintered ore quality in the upper layer of the sintered layer 3, it is preferable to supply 23.3 to 372.0 MJ/ ^m2 of biomass fuel onto the sintered raw material layer 2 in terms of heat amount per unit area.
The lower limit of the supply amount of biomass fuel is more preferably 30.0 MJ/ ^m2 or more, and even more preferably 46.5 MJ/m2 or ^more .
The upper limit of the supply amount of biomass fuel is more preferably 279.0 MJ/ ^m2 or less, and even more preferably 186.0 MJ/m2 or ^less .

In the fuel supply device 50 (i.e., the fuel supply process), the biomass fuel 4 supplied onto the sintering raw material layer 2 needs to spontaneously burn due to the sensible heat of the ignited sintering raw material layer. To achieve this, it is preferable to supply the biomass fuel 4 onto the sintering raw material layer 2 when the temperature of the surface of the ignited sintering raw material layer 2 is 400°C or higher. To achieve this, it is preferable to supply the biomass fuel 4 before the surface temperature of the ignited sintering raw material layer 2 has completely cooled, that is, within a predetermined time after ignition.

Specifically, it is preferable to supply the biomass fuel 4 onto the sintering raw material layer 2 within 60 seconds immediately after the completion of ignition of the surface portion of the sintering raw material layer 2 by the ignition furnace 40.
The upper limit of the timing for supplying the biomass fuel 4 is preferably within 30 seconds, and more preferably within 10 seconds.
However, from the viewpoint of preventing contact of the flame of the ignition furnace 40 with the biomass fuel 4 supplied onto the sintering raw material layer 2, the lower limit of the timing of supplying the biomass fuel 4 is preferably 1 second or more immediately after the completion of ignition of the surface portion of the sintering raw material layer 2 by the ignition furnace 40.

The supply position of the biomass fuel 4 is preferably within 3.0 m, more preferably within 1.5 m, and even more preferably within 0.5 m from the position immediately after the completion of ignition of the surface layer of the sintering raw material layer 2 by the ignition furnace 40. However, the lower limit of the supply position of the biomass fuel 4 is 0.1 m or more.

Note that "immediately after the surface portion of the sintered raw material layer 2 is ignited by the ignition furnace 40" refers to the point in time when the surface of the sintered raw material layer 2 separates from the plane formed by the edge line of the discharge side of the ignition furnace 40 and the vertical direction.

(Fire prevention devices)
The fire prevention device 60 is a device that prevents the flame of the ignition furnace 40 from coming into contact with the biomass fuel 4 supplied onto the sintering raw material layer 2.
The fire prevention device 60 has a fire wall 61 (e.g., a fire wall made of a metal plate, insulating material, etc.) provided between the ignition furnace 40 and the fuel supply device 50 (specifically, for example, the point where the biomass fuel 4 is supplied onto the sintering raw material layer 2).

Here, if the biomass fuel 4 after being supplied onto the sintering raw material layer 2 is only burned by the flame of the ignition furnace 40, no particular problem will occur. However, in a situation in which the flame of the ignition furnace 40 causes the biomass fuel 4 to ignite, there is a risk that the biomass fuel 4 before being supplied will also burn. Therefore, the fire prevention device 60 prevents the biomass fuel 4 supplied onto the sintering raw material layer 2 from being burned by the flame of the ignition furnace 40, thereby improving the safety of the process.

(Crushing and sizing equipment)
The crushing and sieving device 70 has, for example, a primary crusher 71, a cooler 72, a primary sieve 73, a secondary crusher 74, a secondary sieve 75, and a tertiary sieve 76.
The primary crusher 71 is a crusher that roughly crushes the sintered layer 3 obtained by using the fuel of the sintering raw material layer 2 .
The cooler 72 is a cooler that cools the sintered ore roughly crushed by the primary crusher 71 .
The primary sieve 73 is a sieve for granulating the sintered ore cooled in the cooler 72 .
The secondary crusher 74 is a crusher that crushes the sintered ore remaining on the primary sieve 73 .
The secondary sieve 75 is a sieve for granulating the sintered ore granulated by the primary sieve 73 and the sintered ore pulverized by the secondary pulverizer 74 .
The tertiary sieve 76 is a sieve that sieves the sintered ore sized by the secondary sieve 75 .

Then, the agglomerates of about 5 mm or more that have been crushed and sized by the crushing and sizing device are supplied to the blast furnace as finished sintered ore. On the other hand, sintered ore less than about 5 mm is mixed into the sintering raw material as return ore.

(Exhaust gas equipment)
The exhaust gas device 80 includes, for example, a wind box 81 installed under each sintering pallet 11, a main exhaust gas pipe 83 connected to the wind box 81 via a connecting pipe 82, and an electric dust collector 84, an exhaust fan 85, and a chimney 86 provided on the exhaust gas side of the main exhaust gas pipe 83.

In the exhaust gas device 80, the exhaust fan 85 creates negative pressure in the wind box 81, sucking air from above to below the sintering raw material layer 2, supplying air to the inside of the sintering raw material layer 2 and sucking in the combustion gas generated by the fuel in the sintering raw material layer 2. The combustion gas sucked in through the connecting pipe 82 and the main exhaust gas pipe 83 is exhausted from the chimney 86 after the dust in the combustion gas is collected by the electric dust collector 84.

In the sintering machine 101 and its operating method of the present invention described above, a layer of biomass fuel 4 (not shown) is formed on the sintering raw material layer 2 after ignition by the fuel supply device 50, and the biomass fuel 4 is spontaneously burned by the sensible heat of the ignited sintering raw material layer 2, thereby increasing the combustion efficiency of the upper layer of the sintering raw material layer 2 and improving the quality of the sintered ore in the upper layer of the sintering layer 3.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Water was added to the raw material mixture having the composition shown in Table 1 so that the moisture content was 7.3%, and after mixing for 60 seconds, the mixture was granulated in a granulator for 240 seconds to prepare a sintering raw material.
However, in Examples 4 to 6, the sintering raw materials were prepared with a reduced amount of coke. The amount of coke was reduced so that the total calorific value (calories) of the sintering raw materials including the "sawdust" and the sintering raw materials was the same as that of Comparative Example 1 (i.e., the calorific value of the sintering raw materials themselves).
Here, the combustion heat of sawdust was assumed to be 15 MJ/kg. In Example 6, the amount of coke in the granulated raw material was approximately half that in Comparative Example 1. However, since the ratio of the biomass fuel charged on the surface of the sintering raw material to the coke in the sintering raw material varies depending on the thickness of the sintering layer, even when the same amount of biomass fuel as in Example 6 is used per unit area, the ratio of the coke charged varies from the above depending on the layer thickness.
The chemical composition of the coke is shown in Table 2.

Next, a test apparatus was prepared (see FIG. 2).
As shown in Fig. 2, the test device 200 was attached to a 9 mm thick grate (lower mesh) 204 at the bottom of a container 202A of a cylindrical pot 202 (a cylindrical body with an inner diameter of 284 mm and an outer diameter of 19 mm) that contains a sintering raw material 201. Also, a heat insulating material (glass wool) 206 with a thickness of about 10 mm was fixed to the inner surface of the container 202A of the pot 202.
Next, in a state where an alumina tube 208 (Trio Ceramics, PTO series, inner diameter 1.2 mm, outer diameter 1.8 mm, length 440 mm) was held vertically with a thread in the storage section 202A of the pot 202, bedding ore (return ore) 201A was laid on the grate (lower net) of the storage section 202A of the pot 202 to a thickness of about 20 mm. After that, the sintering raw material 201 was charged into the storage section 202A of the pot 202. The thickness of the charged sintering raw material 201 (hereinafter, sintering raw material layer 201) was about 280 mm.
Next, a thermocouple 210 (a high temperature resistant sheathed K thermocouple, Okazaki Seisakusho, HOSKINS2300 series, outer diameter: 1.0 mm, sheath length: 460 mm) was inserted into the alumina tube from the bottom of the pot.
Meanwhile, an electric slider 220 (EAS series, manufactured by Oriental Motor Co., Ltd.) for vertically moving the thermocouple 210 was disposed below the container 202A of the cylindrical pan 202. The sleeve of the thermocouple 210 was then fixed to the stage of the electric slider 220.

In this manner, the test device 200 was prepared.

The following tests were carried out using the test device 200. The test conditions are shown in Table 3.
First, air was made to flow from the top to the bottom of the sintering raw material layer 201 in the pot 202 at 2.0 m3/min.
Next, the surface of the sintering material layer 201 in the pot 202 was ignited by a cylindrical burner. 75 L/min of propane gas (LPG) and 2,300 L/min of air were supplied to the cylindrical burner.
Next, after the surface of the sintering raw material layer 201 was ignited, sawdust was poured in as a biofuel under some test conditions to cover the surface of the sintering raw material layer. However, the sawdust pouring speed was adjusted so that the thickness of the sawdust layer did not exceed 50 mm.

Meanwhile, from the start of ignition of the surface layer of the sintering raw material layer 201, the thermocouple 210 was moved up and down within the alumina tube 208 by the operation of the electric slider 220. The operating speed (scanning speed) of the electric slider 220 was 3 mm/min in the upward direction and 5 mm/min in the downward direction, and the temperature was recorded every 0.1 s by a data logger.

Then, the temperature was measured from the start of ignition of the surface layer of the sintering raw material layer 201 to the completion of the sintering reaction, and the acquired data was analyzed by MATLAB. As a result, the average value of the high-temperature holding time (s) during which the temperature of the upper layer of the sintering raw material layer 201 was held at 1100°C or higher from the start of ignition of the surface layer of the sintering raw material layer 201 was examined.
The temperature measurements were carried out according to the literature (K Taira, M Matsumura, ISIJ International 58 (5), 808-814).

In addition, the concentrations of O2, CO2, CO, and NO in the exhaust gas were analyzed using a gas analyzer (Shimadzu Corporation, CLM-108, URA-208) from the start of ignition of the surface layer of the sintering raw material layer 201 to the completion of the sintering reaction.

The sintered layer, after the sintering reaction was completed, was divided into two approximately equal halves, top and bottom, and each was subjected to a shutter test and sieved, and the proportion of fractions 5 mm or larger was evaluated as the yield.

The results of each test are shown in Table 3. The combustion heat per unit area of the input biomass fuel is also shown in Examples 1 to 7. From the above results, it can be seen that the yield of the upper layer of the sintered layer is improved in this Example compared to the Comparative Example.
3 to 5 show the change in exhaust gas composition during the sintering reaction in Comparative Examples 1 and 2 and Example 1. From the above results, it can be seen from Fig. 3 to Fig. 5 together with Table 1 that this Example has reduced NOx emissions compared to the Comparative Examples. And, it can also be seen that this Example uses sawdust as a biomass fuel to improve the yield of the upper layer of the sintered layer, thereby realizing a reduction in _CO2 emissions.

Here, regarding the holding time (s) from the start of ignition of the surface layer of the sintering raw material layer to the holding time of the upper layer of the sintering raw material layer at 1100°C or higher, it can be seen that by adding biomass fuel to the surface of the sintering raw material layer, the high temperature holding time of the upper layer of the sintering raw material layer in particular was extended. Also, it can be seen that the higher the amount of sawdust supplied, the longer the high temperature holding time of the upper layer of the sintering raw material layer, both in the cases where there is no reduction in the coke ratio (Examples 1 to 3) and where there is (Examples 4 to 6).

Next, focusing on the amount of NOx generated, it can be seen that in both cases where there is no reduction in the amount of coke (Examples 1 to 3) and where there is a reduction in the amount of coke (Examples 4 to 6), the greater the amount of sawdust supplied, the lower the NOx concentration in the exhaust gas. On the other hand, comparing Example 1 with Example 7, where the waiting time from burner ignition to biomass fuel input is long, the NOx concentration is higher than in Example 1, where the waiting time is short, and the high temperature retention time for the upper layer of the sintering raw material layer is also shorter.

In this embodiment, the test is carried out under the condition that the thickness of the sintering raw material layer is 280 mm. In the embodiments 4 to 6, the coke is reduced by the amount of the combustion heat of the biomass fuel, and the reduction ratio is about 12.5% in the embodiment 4, about 25% in the embodiment 5, and about 50% in the embodiment 6. In an actual sintering machine, the thickness of the sintered layer is often about twice as thick as that of the embodiment, that is, about 600 mm. Therefore, if it is assumed that the coke can be reduced at the same ratio as in the embodiment, it is considered possible to add about twice the amount of biomass fuel shown in the embodiment. That is, it is estimated that it is possible to increase the amount of biomass fuel to 372 MJ/m ² , which is twice the amount of 186 MJ/m ² shown in the embodiment 6. On the other hand, if a sufficient amount of biomass fuel is not available, it is considered necessary to reduce the amount of biomass fuel used from the amount shown in the embodiments 1 to 6. As shown in Examples 1 and 4, a sufficient effect is exhibited even at 46.5 MJ/ ^m2 , so it is estimated that a sufficient effect is also exhibited at half that amount, 23.3 MJ/ ^m2 .

1 Sintering raw material 2 Sintering raw material layer 3 Sintering layer 4 Biomass fuel 5 Fuel supply device 10 Sintering pallet group 11 Sintering pallet 20 Flooring supply device 21 Flooring hopper 30 Raw material supply device 31 Surge hopper 32 Feeder 40 Ignition furnace 41 Furnace body 42 Burner 50 Fuel supply device 51 Surge hopper 52 Feeder 60 Fire prevention device 61 Fire wall 70 Grinding and sizing device 71 Primary grinder 72 Cooler 73 Primary sieve 74 Secondary grinder 75 Secondary sieve 76 Tertiary sieve 80 Exhaust gas device 81 Wind box 82 Connecting pipe 83 Main exhaust gas pipe 84 Electric dust collector 85 Exhaust fan 86 Chimney

Claims (9)

A sintering pallet group in which a plurality of sintering pallets are connected together;
A raw material supplying device for supplying raw material for sintering into the sintering pallet;
an ignition furnace that ignites a surface portion of the layer of the sintering raw material supplied into the sintering pallet with a flame;
A fuel supply device is provided on the discharge side of the ignition furnace and supplies biomass fuel onto the layer of sintering raw material to spontaneously combust the biomass fuel by sensible heat of the surface layer of the ignited sintering raw material layer;
A sintering machine comprising: The sintering machine according to claim 1 , wherein the fuel supply device is capable of adjusting the amount of the biomass fuel supplied. The sintering machine according to claim 1 or 2 , wherein the fuel supplying device is a device that supplies the biomass fuel onto the layer of the sintering raw material in an amount of 23.3 to 372.0 MJ/ ^m2 in terms of heat per unit area. The sintering machine according to any one of claims 1 to 3, wherein the fuel supply device is a device that supplies the biomass fuel onto the layer of the sintering raw material within 60 seconds immediately after the completion of ignition of the surface layer of the sintering raw material by the ignition furnace. The sintering machine according to any one of claims 1 to 4 , further comprising a fire prevention device for preventing a flame of the ignition furnace from coming into contact with the biomass fuel supplied on the layer of the sintering raw material. a raw material supplying step of supplying a sintering raw material into a sintering pallet in a sintering pallet group in which a plurality of sintering pallets are connected to each other;
Ignite the surface layer of the layer of the sintering raw material supplied into the sintering pallet with a flame of an ignition furnace;
A fuel supplying step of supplying biomass fuel onto the layer of sintering raw material on the discharge side of the ignition furnace so that the biomass fuel is spontaneously combusted by the sensible heat of the surface layer of the ignited sintering raw material layer;
The method for operating a sintering machine comprises the steps of: The method for operating a sintering machine according to claim 6 , wherein in the fuel supplying step, the biomass fuel is supplied onto the layer of the sintering raw material in an amount of 23.3 to 372.0 MJ/m2 in terms of heat per unit area. 8. The method for operating a sintering machine according to claim 6 or 7, wherein in the fuel supplying step, the biomass fuel is supplied onto the layer of sintering raw material within 60 seconds immediately after the completion of ignition of the surface portion of the layer of sintering raw material by the ignition furnace. The method for operating a sintering machine according to any one of claims 6 to 8 , further comprising a fire prevention device for preventing a flame of an ignition furnace from coming into contact with the biomass fuel supplied onto the layer of sintering raw material.