JP2021134426A - Manufacturing method of sintered ore - Google Patents

Abstract

To improve productivity by a two-stage ignition sintering method.SOLUTION: A manufacturing method of sintered ore includes: a step for forming a lower-stage raw material packed bed by charging a blended raw material for a lower stage into a sintering machine; a step for forming an upper-stage raw material packed bed by charging a blended raw material for an upper stage onto the lower-stage raw material packed bed; and a step for igniting the surface of the lower-stage raw material packed bed and the upper-stage raw material packed bed individually, and also sucking oxygen-containing gas in the lower-stage raw material packed bed and the upper-stage raw material packed bed downward. In the manufacturing method of sintered ore, the calorific volume of an iron-containing substance having an oxidation heat generation property, blended in the blended raw material for the upper stage, per unit new raw material is made larger than the calorific volume of an iron-containing substance having an oxidation heat generation property, blended in the blended raw material for the lower stage, per unit new raw material.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a sinter for producing a sinter for a blast furnace raw material.

Currently, the main raw material for blast furnace ironmaking is sinter. Sintered ore is usually produced as follows. First, as raw materials for sinter production, iron raw materials such as iron ore (powder), iron-containing miscellaneous raw materials such as scale and iron-making dust, MgO-containing auxiliary raw materials such as sinter, CaO-containing auxiliary raw materials such as limestone, and return ore. , Carbon material (condensing material), which is a fuel for sintering (coagulating) sinter by heat of combustion, is mixed at a predetermined ratio. The mixed compounded raw material is granulated to obtain a compounded raw material granulated product. Next, the compounded raw material granulated product is mounted on a pallet (sintered pallet) of a downward suction type Dwightroid (DL) type sintering machine from a hopper to form a raw material filling layer. From the upper part (surface) of the formed raw material filling layer, the charcoal material in the raw material filling layer is ignited by an ignition furnace (igniter). Then, air is sucked from below the pallet while continuously moving the pallet. Oxygen is supplied into the raw material filling layer by suction, combustion of the charcoal material in the raw material filling layer proceeds from the upper part to the lower part, and the raw material filling layer is sequentially sintered by the combustion heat of the carbonaceous material. The sintered portion 3 (sinter cake) obtained by sintering is pulverized to a predetermined particle size, sized by sieving, etc., and becomes a sintered ore which is a raw material of a blast furnace.

In the method for producing a sintered ore by such a DL type sinter, a multi-stage charging multi-stage ignition sintering method in which a raw material packing layer is formed and ignition is performed in multiple stages of two or more stages has been proposed. In the multi-stage charging multi-stage ignition sintering method, the granulated compounded raw materials are sequentially charged in the layer height direction of the sintering machine to form a multi-stage (two or more stages) raw material filling layer and the surface of each raw material filling layer. Is ignited and air is sucked from below, so that the sintering reaction of each layer proceeds in parallel at the same time to sinter.

FIG. 1 is a schematic view of a DL type sintering machine used in a two-stage charging two-stage ignition sintering method, which is an example of a multi-stage charging multi-stage ignition sintering method. With reference to FIG. 1, the granulated compounding raw material is charged in two stages to form an upper raw material filling layer (hereinafter referred to as an upper layer) and a lower raw material filling layer (hereinafter referred to as a lower layer). A two-stage charging two-stage ignition sintering method in which each of the layer and the lower layer is ignited to perform sintering will be described.

In the example shown in FIG. 1, the upper compounding material forming the upper layer 20 and the lower compounding material forming the lower layer 10 are prepared in separate systems (two systems), and the sintering machine 100 is prepared in another system. It is loaded on a pallet (not shown). Specifically, the raw material for the lower stage, stored in each raw material tank of the lower raw material tank group _1D (1D 1 ~1D _X) in the required type and amount of the raw material is blended with cut out at a predetermined rate .. The blended raw material for the lower stage (blended raw material for the lower stage) is charged into the drum mixer 1A for the lower stage, mixed, and water is added to granulate. Further, the raw materials for the upper stage _{are stored in each raw material tank (2D 1 to 2D y} ) of the upper raw material tank group 2D, and the required types and amounts of raw materials are cut out at a predetermined ratio and blended. The blended raw material for the upper stage (blended raw material for the upper stage) is charged into the upper drum mixer 2A, mixed, and water is added to granulate.

The granulated lower compound raw material (lower compound raw material granulated product) is charged from the lower hopper 1B onto a pallet lined with bedding ore to form the lower layer 10 (lower raw material filling layer). do. The lower layer 10 moves to the bottom of the lower igniter 1C by moving the pallet in the pallet traveling direction 5, where the carbon material on the surface of the lower layer 10 is ignited by the lower igniter 1C. After ignition, the lower layer 10 is started to be sintered by the lower suction 6 that sucks air from below through the air box (not shown) under the pallet. The sintering of the lower layer 10 proceeds downward by the subsequent downward suction 6, and forms the lower layer combustion zone 10A.

When the lower layer 10 from which sintering has started moves to the bottom of the upper hopper 2B, the upper compounded raw material (upper compounded raw material granulated product) granulated by the upper drum mixer 2A starts from the upper hopper 2B. , It is charged onto the lower layer 10 after ignition to form the upper layer 20 (upper raw material filling layer). The upper layer 20 moves to the bottom of the upper igniter 2C by moving the pallet in the pallet traveling direction 5, where the carbon material on the surface of the upper layer 20 is ignited by the upper igniter 2C. After ignition, the lower suction 6 starts sintering of the upper layer 20. The sintering of the upper layer 20 proceeds downward by the subsequent downward suction 6, and forms the upper layer combustion zone 20A.

The lower layer combustion zone 10A of the lower layer 10 and the upper layer combustion zone 20A of the upper layer 20 are simultaneously sintered and lowered by the further downward suction 6. When the lower layer combustion zone 10A and the upper layer combustion zone 20A reach the bottom of each layer, sintering by combustion of the carbonaceous material is completed, and the lower layer 10 and the upper layer 20 become the sintered portion 3. Finally, the sintered portion 3 that has been sintered is discharged from the end of the pallet.

In the two-stage charging two-stage ignition sintering method, the raw material filling layer is made into two stages, and the sintering proceeds simultaneously in the two stages, so that the production amount can be substantially doubled. Further, since the exhaust gas used for sintering the upper layer 20 is reused for sintering the lower layer 10 by downward suction, the amount of exhaust gas can be reduced (halved).

The multi-stage charging multi-stage ignition sintering method is disclosed in Patent Documents 1 and 2. According to Patent Document 1, since the multi-stage charging multi-stage ignition sintering method can change the supply ratio of the raw materials of each layer, the yield can be improved by adjusting the particle size of the raw materials of the upper layer 20 and the lower layer 10. It is stated that it will be done.

In Patent Document 2, as an essential drawback of the two-stage ignition type sintering method, the fuel blended in the intake / output side layer is blended because the oxygen concentration of the gas flowing from the intake inlet side layer to the intake / output side layer is low. However, it has been pointed out that the incomplete combustion state is likely to occur, and the calorific value of combustion is reduced, so that the temperature inside the layer is lowered and sufficient melt sintering cannot be performed, resulting in deterioration of the strength of the product sinter. In the two-stage charging two-stage ignition sintering method, the gas (exhaust gas) used for sintering the upper layer 20 and whose oxygen partial pressure is lowered is supplied to the lower layer 10 by the lower suction 6, and the lower layer 10 is supplied with gas (exhaust gas). Used for sintering. Therefore, the lower layer 10 is sintered under a low oxygen partial pressure, the combustion of the carbonaceous material in the lower layer 10 is incomplete, and the amount of heat required for sintering is insufficient. Due to the insufficient amount of heat, the progress of the sinter reaction of the lower layer 10 is hindered, and the strength of the sinter of the lower layer 10 decreases.

As a solution to this problem, Patent Document 2 states that the fixed carbon concentration in the compounding raw material layer (lower raw material filling layer) on the intake side of the two layers is set to 0 or 2 wt% or less, and instead, it can be oxidized as a fuel. A technique for blending a raw material containing any one or more of _{metallic iron, FeO, and Fe 3} O ₄ , which are iron-containing substances, is disclosed. By blending a raw material containing an iron-containing substance that generates heat of oxidation into the blended raw material of the intake outlet side layer, it is possible to obtain a sufficient calorific value for melt sintering even with a gas having a low oxygen concentration, and sintering. It is stated that the productivity of the machine can be significantly improved.

Japanese Unexamined Patent Publication No. 47-26304 Japanese Unexamined Patent Publication No. 09-279261

The present invention is a method for producing a sinter newly devised in view of the above problems. An object of the present invention is the production of a sinter capable of further improving productivity (production rate) in a two-stage charging two-stage ignition sinter method (hereinafter, also simply referred to as a two-stage ignition sintering method). To provide a method.

The present invention has been made to solve the above problems, and the gist thereof is as follows.
(1) The process of forming the lower raw material filling layer by charging the lower raw material into the sintering machine, and
A step of forming an upper raw material filling layer by charging the upper mixed raw material onto the lower raw material filling layer, and a step of forming the upper raw material filling layer.
The steps include igniting the surface of the lower raw material filling layer and the surface of the upper raw material filling layer, respectively, and sucking the oxygen-containing gas in the lower raw material filling layer and the upper raw material filling layer downward.
Unit of iron-containing substance having oxidative heat generation compounded in the lower compounding raw material Unit of iron-containing substance compounded in the upper compounding material Rather than the calorific value per new raw material The amount of heat generated is large,
A method for producing a sinter, which is characterized in that.
(2) When a single raw material containing an iron-containing substance having an oxidative exothermic property is used in the upper compounding material and the lower compounding material.
The blending ratio (mass%) of the raw material containing the iron-containing substance having oxidative heat generating property to be blended in the upper compounding raw material in the new raw material is the iron content having oxidative heat generating property to be blended in the lower compounding raw material. It is larger than the compounding ratio (mass%) of the raw material containing the substance in the new raw material.
The method for producing a sinter according to (1).
(3) The particle size of the charcoal material blended in the upper compounding raw material is larger than the particle size of the charcoal material blended in the lower compounding raw material.
The method for producing a sinter according to (1) or (2).

According to the present invention, the productivity of the two-stage ignition sintering method can be improved by increasing the amount of the upper layer of the iron-containing substance having oxidative heat generation to be larger than that of the lower layer.

It is a schematic diagram of the DL type sintering machine used for the two-stage ignition sintering method. It is a figure which shows the raw material processing process of the two-step ignition sintering method which is one Embodiment of this invention.

As described above, the two-stage ignition sintering method has a problem of lowering the sintering strength of the sinter in the lower raw material filling layer (lower layer 10). Unlike Patent Document 2, the present inventor presents the exhaust gas having a high oxygen concentration in the upper layer 20 as the lower layer 10 as a new viewpoint for the two-stage ignition sintering method in which the decrease in strength of the lower layer sinter is a problem. I came up with the idea of using a heat source that can be supplied to.

In the two-stage ignition sintering method, the present invention has an oxidative heat generation property to be blended in the upper compounding raw material rather than the calorific value per unit new raw material of the iron-containing substance having oxidative heat generation property to be blended in the lower step compounding raw material. It is characterized by a large calorific value per unit new raw material of the iron-containing substance having. Further, when a single raw material containing an iron-containing substance having an oxidative heat-generating property is used for the upper-stage compounding raw material and the lower-stage compounding raw material, the iron-containing substance having an oxidative heat-generating property to be blended in the upper-stage compounding raw material. The blending ratio (mass%) of the raw material containing the above in the new raw material is larger than the blending ratio (mass%) of the raw material containing the iron-containing substance having oxidative heat generating property to be blended in the lower blending raw material. It may be increased. Here, the iron-containing substance having oxidative heat-generating property (hereinafter, also referred to as iron-containing substance F) is metallic iron (Fe), wustite (FeO), and magnetite (Fe ₃ O _{4), which are iron components having oxidative heat-generating property.} ) Is a substance containing at least one of. The raw material containing the iron-containing substance F having an oxidative heat-generating property (hereinafter, appropriately referred to as a heat-generating raw material) is reduced iron powder, scale, converter dust, steel can chips and the like. In addition, iron ore containing at least one of metallic iron (Fe), wustite (FeO), and magnetite (Fe ₃ O _{4), which are iron components having oxidative heat generation properties, also contains iron content.} It is contained in the raw material containing the contained substance F.

In the sintering process under high temperature, metallic iron (Fe), wustite (FeO), and magnetite (Fe ₃ O ₄ ) are oxidized. For example, metallic iron (Fe) and wustite (Fe _{O) are magnetite (Fe 3} O). ₄ ) and hematite (Fe ₂ O ₃ ), and magnetite (Fe ₃ O ₄ ) are changed to hematite (Fe ₂ O _3). These oxidation reactions are exothermic reactions. In the conventional method for producing a sintered ore, a heat-generating raw material such as scale is blended as an iron-containing miscellaneous raw material in a compounding raw material for effective utilization of an iron component, and is used at a uniform concentration in the entire raw material packing layer. It is common. Further, as described above, since the iron-containing substance F causes an exothermic reaction in the sintering process, a heat-generating raw material can be used as a heat-generating source instead of the coagulant.

As a result of various studies on the means for improving the two-stage ignition sintering method, the present inventor has improved the combustibility of the carbonaceous material in the lower layer and improved the productivity by using the heat-generating raw material as the heat generating source in the upper layer. Was found to be feasible. As shown in Example (Experiment 2) described later, when a heat-generating raw material is used as a heat-generating source, oxygen remains in a higher concentration in the sintered exhaust gas than when a charcoal material (coke or the like) is used. By using a heat-generating raw material as a heat-generating source in the upper layer and reducing the amount of carbonaceous material corresponding to the iron-containing substance F contained therein, the sintered exhaust gas in the upper layer is placed in the lower layer with oxygen remaining in a high concentration. When supplied, the amount of heat required for sintering can be secured in the lower layer, and productivity can be improved.

Scales, which are heat-generating raw materials, are not limited to the two-stage ignition sintering method, but are usually used as iron-containing miscellaneous raw materials. In the conventional two-stage ignition sintering method, it can be considered that the heat-generating raw material is blended in the same ratio in the new raw material of the lower-stage compounding raw material and the new raw material of the upper-stage compounding raw material. In the present invention, as described above, the amount of heat generated per unit new raw material of the iron-containing substance F blended in the lower-stage compounding raw material is higher than the calorific value per unit new raw material of the iron-containing substance F blended in the upper-stage compounding raw material. Based on the blending ratio (mass%) of the iron-containing substance F in the new raw material to be blended in the lower-stage compounding material, or to increase the amount, the iron-containing substance F to be blended in the upper-stage compounding material is higher than the blending ratio. By increasing the compounding ratio (mass%) of, the oxygen concentration in the sintered exhaust gas of the upper layer supplied to the lower layer is increased.

When a plurality of exothermic raw materials are used, the calorific value per unit new raw material is used as an index instead of the blending ratio in the new raw material. Then, the calorific value per unit new raw material of the iron-containing substance F blended in the upper compound raw material is made larger than the calorific value per unit new raw material of the iron-containing substance F blended in the lower compound raw material.
Here, it is preferable to adjust the blending ratio of the charcoal material to be blended in the upper blended raw material based on the calorific value of the iron-containing substance F blended in the upper blended raw material.
Further, it is also preferable to adjust the blending ratio of the iron ore and the CaO-containing auxiliary raw material to be blended in the upper blended raw material based on the basicity (CaO / SiO _{2: mass%) of the lower blended raw material.} This makes it possible to stabilize the quality of the sinter.

FIG. 2 is a diagram showing an example of a raw material processing step for carrying out the method for producing a sinter by the two-stage charging two-stage ignition sintering method of the present invention. The steps after charging the lower-stage compounded raw material into the lower-stage drum mixer 1A and charging the upper-stage compounded raw material into the upper-stage drum mixer 2A are the same as the above-mentioned sinter manufacturing process using FIG. The DL type sintering machine 100 shown in FIG. 1 is used for sintering.

As shown in FIG. 2, in the present embodiment, the heat-generating raw material containing the iron-containing substance F is placed in the raw material tank 1D _{1 of the lower raw material tank group 1D and in the raw material tank 2D 1} of the upper raw material tank group 2D. It is stored. The amount cut out when the heat-generating raw material in the raw material tank 2D ₁ is mixed with other upper-stage compounding raw materials, and the amount cut out when _{the heat-generating raw material in the raw material tank 1D 1} is mixed with other lower-stage compounding raw materials. The amount to be blended is appropriately adjusted, and the blending ratio of the iron-containing substance F in the upper-stage blending raw material and the blending ratio of the iron-containing substance F in the lower-stage blending raw material are set to the predetermined blending amounts.

The storage of the heat-generating raw materials of the upper-stage compounding raw material and the lower-stage compounding raw material is not limited to the above-mentioned form, and the compounding ratio of the iron-containing substance F in the upper-stage compounding raw material and the iron-containing substance in the lower-stage compounding raw material are not limited to the above-mentioned forms. It suffices that the blending ratio of F is configured to be a predetermined amount. For example, when a plurality of types of heat-generating raw materials are blended as the upper-stage compounding raw material, each type is separately stored in the raw material tank 2Dn (1 ≦ n ≦ y), and the amount cut out from the raw material tank 2Dn for each type. May be adjusted, or a mixed raw material in which a plurality of types of heat-generating raw materials are mixed in a predetermined ratio is stored in one raw material tank 2Dm (1 ≦ m ≦ y), and the mixed raw material is cut out from the raw material tank 2Dm. The amount may be adjusted. The same applies to the lower compounding raw materials. Further, the lower-stage compounding raw material does not have to be provided with a raw material tank 1Dn (1 ≦ n ≦ x) or a raw material tank 2Dm (1 ≦ m ≦ y) for storing the heat-generating raw material. This is because it is not necessary to add a heat-generating raw material to the lower-stage compounding raw material.

Further, in the embodiment shown in FIG. 2, the upper raw material tank group 2D and the lower raw material tank group 1D are provided, and the upper mixed raw material and the lower mixed raw material are prepared in separate systems and charged on the pallet. Sintered ore is manufactured by the two-stage ignition sintering method. After mixing the raw materials at a predetermined mixing ratio, the raw materials are divided into the upper raw material and the lower raw material, and the lower raw material is heat-generating. The raw material may be post-added to obtain a compounding raw material for the lower stage, and the raw material for the upper stage may be used as it is as a compounding raw material for the upper stage, and each of them may be granulated and charged into a sintering machine.

As for the charcoal material to be blended in the blending raw material, it is preferable that the particle size of the charcoal material blended in the upper blending raw material is larger than the particle size of the charcoal material blended in the lower blending raw material. Coarse-grained carbonaceous material consumes less oxygen per unit suction air amount. By making the particle size of the carbonaceous material mixed in the upper compounding raw material larger than that in the lower compounding material, the oxygen consumption in the upper layer is reduced. The oxygen concentration in the gas supplied to the lower layer is increased, and the effect of improving the yield of the sinter in the lower layer can be obtained.
Here, the carbonaceous material is a solid fuel containing carbon, and examples thereof include coke breeze, anthracite, and carbon-containing dust. It may have a volatile content, but it is preferable that the content is small.

As the charcoal material, it is preferable to use coke having a particle size of less than 5 mm. Here, the particle size of the carbonaceous material is defined by the mass ratio of particles having a diameter of 3 mm or more (hereinafter, also referred to as a mass ratio having a particle size of 3 mm or more). For example, for a mass ratio of a particle size of 3 mm or more, the carbonaceous material is classified with a 3 mm sieve (a sieve having a mesh size of 2.8 mm of a JIS standard sieve (JIS Z 8801)), and the masses of the upper and lower sieves are measured. , Calculate the mass ratio on the sieve to the entire carbonaceous material. Further, the carbonaceous material blended in the lower compounding raw material has a particle size of 3 mm or more and less than 5 mm in a mass ratio of 10% by mass or less, and the charcoal material blended in the upper compounding raw material has a particle size of 3 mm or more and less than 5 mm. The mass ratio is preferably 10% by mass or more and 25% by mass or less, and more preferably 10% by mass or more and 22% by mass or less. Here, the particle size of 3 mm or more and less than 5 mm means that the sieve is on a sieve of 2.8 mm and is sieved when classified by a sieve having a mesh size of 2.8 mm and a sieve of 4.75 mm, which are JIS standard sieves (JIS Z 8801). Refers to the portion under the sieve of 4.75 mm. Normally, as the description and designation when classifying the particle size, approximate values of 3 mm and 5 mm are used for the sieve meshes of 2.8 mm and 4.75 mm. The particle size of the carbonaceous material can be adjusted by shortening and extending the grinding time or changing the sieve mesh.

In the two-stage charging two-stage ignition sintering method, the layer thicknesses of the upper layer and the lower layer are adjusted so that the upper layer and the lower layer complete the sintering substantially at the same time. As a result, the layer thicknesses of the upper layer and the lower layer are almost equal. However, when different raw materials are used for the upper layer and the lower layer, or when the simultaneity at the completion of sintering of the upper and lower layers is not important, a wider layer thickness ratio of the upper layer to the lower layer can be selected. In the embodiment of the two-stage charging two-stage ignition sintering method shown in FIG. 2, the layer thickness ratio of 1: 2 to 2: 1 can be adopted without impairing the equipment efficiency.

Examples of demonstrating the effect of the present invention will be described. The present invention is not limited to the following examples.

≪Experiment 1≫
The inventor confirmed the effect of the present invention by a sintering pot test (diameter 300 mm) capable of simulating sintering with a DL sintering machine. Unlike the DL sintering machine, the sintering pot tester does not move the raw material filling layer by the pallet, but the compounded raw material is charged in a container of a predetermined size, ignited from the upper surface, and sintered by downward suction. It is a test device for advancing. As shown in Table 3 described later, five tests of Comparative Examples, Reference Examples, and Examples 1 to 3 were performed.

(Ingredient combination)
A scale (FeO: 65.9% by mass, M-Fe (metal iron Fe): 3.98% by mass) was used as the heat-generating raw material. Table 1 shows the blending ratio of the raw materials used as the blending raw materials. As shown in Table 1, two types of compounding raw materials, a compounding raw material 1 without scale and a compounding material 2 with scale, were prepared. As the compounding raw material 2, silica stone was used to match the contents _{of the compounding material 1 and SiO 2.} The blending amount of limestone was set to 12% by mass so that the target basicity of the sinter was 1.8. Iron ores A to D are not heat-generating raw materials, and their production areas are different.

For the blended raw material 2 containing the scale, the blended amount (blending ratio) of the carbonaceous material is set to the equivalent amount of the scale blended so that the estimated calorific value in both blended raw materials is the same based on the blended raw material 1 not blended with the scale. , Weight loss adjusted. Specifically, the calorific value of oxidation of the iron-containing substance F in the scale is calculated from the blending amount of the scale (blending ratio 40% by mass) and its chemical composition, and the blending amount of the carbonaceous material corresponding to the calorific value of oxidation is calculated. I asked. The blending amount of the carbonaceous material of the blending raw material 2 is the blending amount of the carbonaceous material corresponding to the calorific value of oxidation obtained from the blending amount of the carbonaceous material of the blending raw material 1 (blending ratio 4.5% by mass) (blending ratio 2. 2% by mass) was subtracted to obtain an amount (blending ratio 2.3% by mass).
Coke was used as the charcoal material (condensing material). The blending ratio of the coke blended in the blended raw material 1 and the blended raw material 2 was 4.5% by mass and 2.3% by mass, respectively, with the new raw material as 100% by mass.

As coke, three types (coke 1 to coke 3) having different particle size distributions were used. Table 2 shows the particle size distribution of three types of coke. As shown in Table 2, coke 1 to coke 3 are all cokes having a particle size of -5 mm (less than 5 mm). For example, coke 1 has a coke having a particle size of less than 3 mm in an amount of 90% by mass. The proportion of coke having a particle size of 3 mm or more and less than 5 mm is 10% by mass. The particle size of coke was adjusted by classification using a sieve.

(Test case)
The test conditions are shown below (see the upper part of Table 3). As shown in Table 3, 5 tests of Comparative Examples, Reference Examples, and Examples 1 to 3 simulating the two-stage charging two-stage ignition sintering method were carried out.
Comparative example (reference conditions for two-stage charging and two-stage ignition)
: Both the upper layer and the lower layer use raw materials that do not contain scale (blended raw material 1).
Coke 1 is used for coke.
Reference example: Only the lower layer uses a raw material containing scale (blended raw material 2).
Coke is the same as the standard condition.
Example 1: A raw material containing scale (blended raw material 2) is used only in the upper layer.
Coke is the same as the standard condition.
Example 2: A raw material containing scale only in the upper layer (blended raw material 2) is used.
As for coke, coke 2 is used only in the upper layer.
Example 3: A raw material containing scale (blended raw material 2) is used only in the upper layer.
As for coke, coke 3 is used only in the upper layer.

(Granulation method)
Each of the compounding raw material 1 and the compounding raw material 2 was granulated collectively. Granulation was carried out by mixing with a test drum mixer (diameter 600 mm, rotation speed 25 rpm) for 4 minutes, adding 6.5% by mass of water to the compounding raw material, and further treating for 4 minutes.

(Charging / ignition method)
Two pots were prepared, a cylindrical lower pot (φ300 mm) having a height of 500 mm and a cylindrical upper pot (φ300 mm) having a height of 300 mm. First, the lower pot and the upper pot were charged with the granulated lower compound raw material and the upper compound raw material, and the layer height of the lower layer was set to 500 mm and the layer height of the upper layer was set to 300 mm. Then, a lower pot having a layer height of 500 mm was set, and the surface of the lower layer was ignited for 1 minute. After that, the upper pot with a layer height of 300 mm is set on the lower pot, and in order to realize the progress of sintering in the upper and lower two stages, after confirming the temperature rise at the position of 290 mm from the lower surface of the lower layer, the upper stage The surface of the layer was ignited for 1 minute. The suction pressure was kept constant at 1500 mmAq (14.7 kPa) from the start of ignition, and the oxygen concentration in the sintered exhaust gas exhausted from below the lower pan was also measured. The oxygen concentration is a value measured by a gas analyzer (magnetic wind analyzer) and is an average value until sintering is completed.

(Sintering time)
The sintering time was measured as follows. A thermocouple was inserted 380 mm from the lower surface of the lower pan and at the position of the air box, and the temperature inside the layer was measured. Since the later one of the completion of sintering of the upper layer and the completion of sintering of the lower layer is regarded as the completion of sintering of the entire raw material filling layer (upper layer and lower layer), the second temperature rise of the thermocouple at the 380 mm position is started. The longer of the time required to reach the time (sintering of the upper layer) and the time required to reach the first peak time of the thermocouple at the airbox position (sintering of the lower layer) is the raw material filling layer. It was taken as the total sintering time. Suction was stopped 3 minutes after the time when the sintering was completed, and the sintering was completed.

(Yield)
Yield was measured as follows. After sintering, the obtained sintered cake was dropped four times from a height of 2 m, and the mass was determined with a particle size of +5 mm (5 mm or more) as a sintered product. The ratio (mass%) of this sintered product to the total mass of the sinter cake was defined here as the product yield (+ 5 mm%).

(Productivity rate)
The production rate was determined by the following formula (5) based on the sintering time measured as described above.
Production rate = product quantity (t) / sintering area (0.07m ² ) / sintering time (day) ・ ・ ・ (5)

(Test results)
The test results are shown in the lower part of Table 3.
As shown in Table 3, in the examples, the yield and the productivity (productivity) were improved as compared with the comparative examples. Although the compounded raw material 2 containing the scale is also used in the reference example, the productivity was further improved in the example in which the compounded raw material 2 was used in the upper layer. In addition, in Examples 1 and 2, the yield was also improved. It is considered that this is because, as shown in Table 3, the exhaust gas oxygen concentration was low in the examples, and the oxygen in the oxygen-containing gas sucked downward was effectively used for sintering.

Further, as shown in Table 3, in Example 2, coke 2 (mass ratio of particle size 3 mm or more is 22 mass%) was used for the upper layer. By increasing the particle size of the coke used, the yield and the productivity were improved as compared with Example 1 (using coke 1 having a particle size of 3 mm or more and a mass ratio of 10% by mass). It is considered that this is because the oxygen concentration in the exhaust gas supplied to the lower layer has increased. In the case of Example 3 in which the particle size of the coke used in the upper layer was larger than that of Example 2, the yield and productivity were still higher than those of Comparative Example, but the yield was higher than that of Example 2. And productivity declined. It is considered that this is because unburned particles remain due to the presence of extremely large coke, which reduces the yield of the upper layer.

≪Experiment 2≫
To supplement the above test, a sintering pot test was performed on coke and scale to compare the oxygen utilization in oxygen-containing gas during the sintering process.

The compounded raw material 1 and the compounded raw material 2 shown in Table 1 were granulated and prepared in the same manner as in the above-mentioned experimental example, and a firing experiment was carried out by a one-stage charging and one-stage ignition method. Each compounded raw material was charged into a cylindrical lower pan (φ300 mm) having a height of 500 mm up to a layer height of 500 mm, and ignited for 1 minute. The suction pressure was constant at 1500 mmAq from the start of ignition. The oxygen concentration in the calcined exhaust gas (exhaust gas oxygen concentration) was measured, and the relationship with the compounding raw material conditions was investigated. As a result, the exhaust gas oxygen concentration was 9.5% in the compounded raw material 1 in which the scale was not compounded. On the other hand, the exhaust gas oxygen concentration of the compounded raw material 2 containing the scale was 11.9%, which was higher than that of the compounded raw material 1. That is, the amount of oxygen consumed (in this embodiment, the scale is used) is consumed when a heat-generating raw material (scale is used in this embodiment) is used as a part of the heat-generating raw material (in this embodiment, a scale is used) rather than using only the carbonaceous material which is a coagulant as the heat-generating source in the firing process. The result was that (oxygen consumption) was low.

In Experiment 1, as shown in Table 3, Example 1 in which the compounding raw material 2 (scale compounding) was used only in the upper layer had a smaller exhaust gas oxygen concentration than the reference example in which only the lower layer was used. In Example 1, oxygen in the oxygen-containing gas sucked downward in the entire upper and lower layers is effectively used for sintering. Further, from the results of Experiment 2, it is considered that the oxygen consumption in the upper layer was smaller in Example 1 than in Reference Example. Therefore, in the reference example, it is assumed that oxygen in the exhaust gas from the upper layer could not be effectively used for sintering in the lower layer. On the other hand, in Example 1, the exhaust gas having a relatively high oxygen concentration from the upper layer is supplied to the lower layer, and the oxygen in the exhaust gas is effectively used for sintering in the lower layer, so that the yield and the production rate are higher. It is expected that it has been improved.

100 ... sintering machine, 1A ... lower drum mixer, 1B ... lower hoppers, 1C ... lower stage igniter, 1D ... lower raw material tank group (the lower raw material tank _1D 1 _~1D X), 2A ... upper drum mixer , 2B ... upper hoppers, 2C ... upper ignition device, 2D ... upper raw material tank group (the upper feed tank _2D 1 _~2D y), 3 ... sintered part, 5 ... pallet advancing direction, 6 ... lower suction, 10 ... Lower layer, 10A ... Lower layer combustion zone, 20 ... Upper layer, 20A ... Upper layer combustion zone

Claims (3)

The process of forming the lower raw material filling layer by charging the lower raw material into the sintering machine, and
A step of forming an upper raw material filling layer by charging the upper mixed raw material onto the lower raw material filling layer, and a step of forming the upper raw material filling layer.
The steps include igniting the surface of the lower raw material filling layer and the surface of the upper raw material filling layer, respectively, and sucking the oxygen-containing gas in the lower raw material filling layer and the upper raw material filling layer downward.
Unit of iron-containing substance having oxidative heat generation compounded in the lower compounding raw material Unit of iron-containing substance compounded in the upper compounding material Rather than the calorific value per new raw material The amount of heat generated is large,
A method for producing a sinter, which is characterized in that. When a single raw material containing an iron-containing substance having oxidative heat generation is used in the upper compounding raw material and the lower compounding material,
The blending ratio (mass%) of the raw material containing the iron-containing substance having oxidative heat generating property to be blended in the upper compounding raw material in the new raw material is the iron content having oxidative heat generating property to be blended in the lower compounding raw material. It is larger than the compounding ratio (mass%) of the raw material containing the substance in the new raw material.
The method for producing a sinter according to claim 1. The particle size of the charcoal material blended in the upper compounding raw material is larger than the particle size of the charcoal material blended in the lower compounding raw material.
The method for producing a sinter according to claim 1 or 2, wherein the sinter is produced.

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