JP7087939B2 - Manufacturing method of sintered raw material - Google Patents

Description

The present invention relates to a method for producing a molded product of a sintering raw material to be charged into a sintering machine.

In Patent Document 1, pseudo-particles obtained by granulating a raw material for sintering and a molded product obtained by compression molding the raw material for sintering are combined and charged into a sintering machine. Here, the diameter of the molded product is 15 mm or more and 20 mm or less, and the crushing strength of the molded product is 36.3 N or more and 41.2 N or less. By producing the sinter using the above-mentioned pseudo particles and the molded product, the air permeability in the raw material layer of the sinter is improved, and the yield and the production rate of the sinter are improved.

Japanese Unexamined Patent Publication No. 2016-02520

According to Patent Document 1, it is considered that the product yield of sintering is lowered due to the laminating phenomenon occurring when the molded product is manufactured by compression molding. That is, the + 5 mm yield of the molded product (residual rate on the sieve of the sieve having a mesh opening of 5 mm) was measured, and the decrease in the product yield of sintering was laminating based on the decrease in the + 5 mm yield. I think it is due to the phenomenon.

However, according to the inventor of the present application, it was found that the decrease in the yield of the molded product by +5 mm, which caused the decrease in the yield of the product, was not solely due to the laminating phenomenon. That is, it was found that if the binder is used appropriately, the yield of sintered products can be improved even if the fractured product produced by the laminating phenomenon of the molded product is positively used, and the invention of the present application is completed. rice field.

The present invention is a method for producing a molded product of a sintered raw material, which is charged into a sintering machine together with pseudo particles obtained by granulating the sintered raw material. A sinter raw material containing 50% by mass or more of fine powder ore and 5 to 20% by mass of binder is compression-molded using a compression molding machine for producing a completely molded product having a major axis of 15 to 30 mm. Then, a half-split molded product to be charged into the sintering machine is manufactured by causing a laminating phenomenon in the completely molded product by the compressive force of the compression molding machine.

The compressive force of the compression molding machine can be a linear pressure of 4 t / cm or more. Further, the average particle size of the compression-molded sintered raw material can be set to 1 mm or less.

In the method for producing a sintered ore according to the present invention, a half-split molded product produced by the above-mentioned method for producing a molded product and pseudo-particles obtained by granulating a sintering raw material are charged into a sinter and sintered. Manufacture ore.

According to the present invention, as a molded product to be charged into a sinter together with pseudo particles, it is possible to produce a molded product (half-split molded product) capable of improving the product yield and production rate of the sinter. can. Here, by using a binder of 5 to 20% by mass, it becomes easy to manufacture a half-split molded product. Further, since the air permeability during firing can be ensured by the outer shape of the half-split molded product, fine powder ore can be positively used as the sintering raw material.

It is a schematic diagram explaining the manufacturing process of a sintered raw material.

In the present embodiment, as a raw material for sintering (hereinafter referred to as a sintering raw material) to be charged into the sintering machine, it is manufactured by compression molding of pseudo particles granulated from the compounding raw material and the compounding raw material. A mixture with a half-split molded product is used. It was found that this improved the product yield and production rate of the sinter. Further, in the present embodiment, a predetermined compounding raw material is used in order to efficiently produce the half-split molded product.

(Mixed raw material)
The compounding raw materials for granulating pseudo-particles include iron ore (including powder ore and fine powder ore), auxiliary raw materials, charcoal materials, return ores and miscellaneous raw materials. The compounding raw material for producing the half-split molded product may contain at least fine ore and binder, and may also contain auxiliary raw materials, charcoal materials, return ores and miscellaneous raw materials.

The powdered ore is a powdered iron ore having a particle size (for example, 10 mm or less) unsuitable for operating a blast furnace. Fine ore is an iron ore whose iron grade is improved by mineral processing of low-grade iron ore rough (called raw ore or ROM) that is not suitable as a raw material for steelmaking, and is also called concentrate or pellet feed. be called. Generally, the fine powder ore has an iron content of 64% or more and an average particle size of 1 mm or less. Here, the average particle size is a value obtained by using the median value of the particle size category as a representative value and weighting and averaging it with the mass ratio of each particle size category. The particle size distribution of the fine ore can be measured based on JIS Z8901.

The auxiliary raw material is a raw material added mainly for the purpose of adjusting the composition of the sinter, and examples of the auxiliary raw material include limestone and quicklime which are calcium sources, dolomite and olivine which are magnesium sources, and the like. .. The charcoal material is used to cause a melt assimilation reaction of iron ore and auxiliary raw materials by generating heat by combustion in the raw material layer. The return ore is a raw material under the sieve when the cake sintered by the sintering machine is crushed and sized, and is reused. The miscellaneous raw materials are slag and dust as recycled raw materials, and are used for recovering and reusing iron and calcium.

(Manufacturing process of sintered raw material)
FIG. 1 is a schematic view showing a manufacturing process of a sintered raw material. This manufacturing process has a main line and a sub line. The main line is a line that manufactures pseudo-particles from compounding raw materials and supplies the pseudo-particles to a sintering machine. The sub-line is a line that manufactures a half-split molded product from a compounded raw material and supplies the half-split molded product in the middle of the main line.

First, the system configuration on the main line will be described below.

A raw material (blended raw material) is charged in each raw material tank 11, and a raw material having a predetermined blending ratio is cut out from each raw material tank 11. The predetermined blending ratio is predetermined in consideration of the target ingredients and properties. The conveyor 12 conveys the raw materials cut out from each raw material tank 11 to the drum granulator 13. The drum granulator 13 produces pseudo-particles by mixing and granulating the raw materials conveyed from the conveyor 12. Here, water adjusted to a water content suitable for granulating the raw material is added to the drum granulator 13. This water content can be determined in advance based on the particle size distribution and water retention of the raw material. The pseudo particles produced by the drum granulator 13 are conveyed to the sintering machine 30 by the conveyor 14.

Next, the system configuration on the sub line will be described below.

Each raw material tank 21 is charged with a raw material (blended raw material), and a raw material having a predetermined blending ratio is cut out from each raw material tank 21. The predetermined blending ratio is predetermined in consideration of the target ingredients and properties. The conveyor 22 conveys the raw materials cut out from each raw material tank 21 to the stirring mixer 23. The stirring mixer 23 stirs and mixes the raw materials conveyed from the conveyor 22, and water adjusted to a water content suitable for compression molding, which will be described later, is added to the stirring mixer 23. This water content can be determined in advance based on the particle size distribution and water retention of the raw material.

The conveyor 24 conveys the raw materials mixed by the stirring mixer 23 to the compression molding machine 25. The compression molding machine 25 has a pair of molding rolls 25a, and a concave cup is formed on the surface (surface in contact with the raw material) of each molding roll 25a. After the raw material is contained in this cup, the raw material in the cup is compressed by the pair of molding rolls 25a to produce a molded product (bricket).

The form of the raw material after passing through the compression molding machine 25 includes a completely molded product, a half-split molded product, and a powdered product. The completely molded product is a compression molded product formed in a shape along the cup of the molding roll 25a. When three axes orthogonal to each other are defined, in a completely molded product, one axial length (hereinafter referred to as a major axis) is longer than each of the other two axial lengths.

The half-split molded product is a compression molded product in which the complete molded product is broken into two from the center in the major axis direction of the completely molded product due to the laminating phenomenon described later. The powder material is a raw material that has passed through the compression molding machine 25 and does not belong to any of the above-mentioned complete molded product and half-split molded product. Completely molded products, half-split products and powdered materials can be distinguished visually by the operator.

The conveyor 26 conveys the half-split molded product produced by the compression molding machine 25 to the conveyor 14. As described above, a completely molded product, a half-split molded product, and a powdered product may be obtained from the compression molding machine 25, but in the present embodiment, only the half-split molded product is used. From the completely molded product, the half-split molded product, and the powdered product, for example, only the half-split molded product can be taken out by a manual operation or a mechanical operation of a worker.

By transporting the half-split molded product to the conveyor 14 via the conveyor 26, the pseudo particles from the drum granulator 13 and the half-split molded product from the compression molding machine 25 are sintered via the conveyor 14. It is transported to the machine 30. The pseudo-particles and the half-split molded product are mixed in the moving path until they are charged into the sintering machine 30. For example, the pseudo-particles and the half-split molded product are charged into the surge tank (not shown) of the sintering machine 30, or the pseudo-particles and the half-split molded product are charged into the sintering machine pallet from the surge tank via a chute. When it does, the pseudo-particles and the half-split molded product are mixed. In the sintering machine 30, baking is performed in a state where the pseudo particles and the half-split molded product are mixed, and a sintered cake is produced. Sintered ore is obtained by crushing the sintered cake to a predetermined particle size.

(Raw material for half-split molding)
The average particle size of the raw material (blended raw material) for producing the half-split molded product may be any size as long as the raw material can be accommodated in the cup of the molding roll 25a. Here, the average particle size can be 1 mm or less. By setting the average particle size of the raw material to 1 mm or less, the raw material can be easily accommodated in the cup of the molding roll 25a, and compression molding can be smoothly performed by the compression molding machine 25.

As the iron ore contained in the raw material, fine powder ore can be mainly used. The blending ratio of the fine ore is 50% by mass or more. As will be described later, considering that the half-split molded product is used to secure the air permeability in the raw material layer of the sintering machine, the particle size is coarser than that of the fine powder ore, and the air permeability in the raw material layer is ensured. For easy powder ore, there is little need to dare to use it as a raw material for half-split moldings. Therefore, as the raw material iron ore, fine powder ore can be positively used. In this embodiment, the raw material may contain powdered ore.

A wet binder is added to the raw material. This binder is used to secure the strength of the half-split molded product while transporting the half-split molded product from the compression molding machine 25 to the sintering machine 30. Examples of the binder include clay-based binders such as fresh lime and bentonite, organic binders such as molasses, and iron ore slurry obtained by wet-crushing iron ore (for example, iron ore slurry described in International Publication No. 2013/054471 pamphlet). Can be used.

The amount of the binder added is 5% by mass or more and 20% by mass or less. This makes it easier to manufacture a half-split molded product. When the iron ore slurry is used as the binder, the mass after the iron ore slurry is completely dried may be within the range of the above-mentioned addition amount of the binder.

(Size of complete molding)
The major axis of the completely molded product depends on the size of the cup of the molding roll 25a, and in the present embodiment, it is 15 mm or more and 30 mm or less. The major axis of the completely molded product is more preferably 20 mm or more and 30 mm or less. In the present embodiment, since the half-split molded product is used, it is preferable that the major axis of the completely molded product is 15 mm or more in order to secure the size of the half-split molded product. Further, considering the moldability by the compression molding machine 25, the major axis of the completely molded product is preferably 30 mm or less.

In the present embodiment, not the completely molded product, but the half-split molded product obtained from the completely molded product is mixed with the raw material (pseudo-particles) of the main line and charged into the sintering machine 30. As a result, the product yield and production rate of the sinter can be improved as compared with the case where the completely molded product is charged into the sinter 30 together with the pseudo particles.

(Molding conditions for compression molding machine)
The condition for compression molding the raw material in the compression molding machine 25 is a condition in which a so-called laminating phenomenon occurs. The laminating phenomenon is a phenomenon in which the completely molded product breaks into two starting from the center of the completely molded product in the major axis direction. As a molding condition for generating the laminating phenomenon, the linear pressure in the compression molding machine 25 can be set to 4 t / cm or more. If the linear pressure is lower than 4 t / cm, the laminating phenomenon does not occur and it may not be possible to manufacture a half-split molded product. Since the occurrence of the laminating phenomenon may depend on the amount of the binder added, the linear pressure in the compression molding machine 25 is not limited to 4 t / cm or more, and the linear pressure capable of generating the laminating phenomenon is not limited to 4 t / cm. It should be.

According to the present embodiment, a fracture surface formed in the half-split molded product in the sintered bed by charging the half-split molded product having a shape different from that of the completely molded product into the sintering machine together with the pseudo particles. It becomes easy to generate voids between (substantially flat surface) and pseudo particles (spheres). Due to this void, the air permeability can be improved, and the product yield and production rate of the sinter can be improved. Further, since the half-split molded product functions as an aggregate, the shrinkage of the cake during firing can be suppressed, and the porosity of the sinter can be improved. As a result, a sinter having excellent reducibility can be produced.

Since the above-mentioned half-split molded product only causes the laminating phenomenon by adjusting the linear pressure in the compression molding machine 25, the half-split molded product can be easily manufactured in the same manufacturing process as the complete molded product. be able to.

(Linear pressure of compression molding machine)
The molded product was manufactured while changing the linear pressure in the compression molding machine 25, and the presence or absence of the laminating phenomenon was confirmed. The linear pressure was set to 3, 4, 5, 6 t / cm, respectively. As a raw material, fine powder ore from Brazil was used as iron ore, and quicklime was used as a binder. A fine powder ore of 95% by mass and quicklime of 5% by mass were blended, and the moisture content of the blended raw material was adjusted to about 5%, which was supplied to the compression molding machine 25. The cup of the molded roll 25a is formed in an almond shape, and the internal volume of this cup is 1.7 cm ³ .

The results of the above-mentioned tests are shown in Table 1 below. In Table 1 below, the ratio of the completely molded product is the ratio (mass%) of the total amount of the completely molded product to the total amount of the compounded raw materials supplied to the compression molding machine 25.

When the linear pressure was 3 t / cm, only a completely molded product and a powdered product were obtained, and the occurrence of the laminating phenomenon could not be confirmed. When the linear pressure was 4,5,63 t / cm, in addition to the completely molded product and the powdered product, a half-split molded product was obtained, and the occurrence of the laminating phenomenon could be confirmed. Therefore, if the linear pressure is set to 4 t / cm or more, the laminating phenomenon can be generated.

(Amount of binder added)
With different amounts of binder added, the ratio (mass%) of the total amount of various molded products to the total amount of compounded raw materials supplied to the compression molding machine 25 was measured for the various molded products after passing through the compression molding machine 25. .. This molded product includes a completely molded product, a half-split molded product, and a residue (referred to as a powder product) excluding the completely molded product and the half-split molded product.

As a raw material, fine powder ore produced in Brazil was used as an iron ore, and a completely dried iron ore slurry was used as a binder. These raw materials were blended and the moisture content of the blended raw materials was adjusted to about 5%, and the mixture was supplied to the compression molding machine 25. The cup of the molded roll 25a is formed in an almond shape, and the internal volume of this cup is 1.7 cm ³ .

The amount of binder (solid content of iron ore slurry) added was set to 0, 5, 10, 20, and 30% by mass, respectively. The blending amount of the fine powder ore was changed according to the amount of the binder added so that the total amount of the fine powder ore and the binder was 100% by mass. That is, the blending amount of the fine powder ore was set to 100, 95, 90, 80, 70% by mass, respectively. The linear pressure of the compression molding machine 25 was set to 4 t / cm based on the results in Table 1 above.

The results of the above tests are shown in Table 2 below.

According to Table 2 above, when the amount of the binder added was 0% by mass, the half-split molded product was hardly produced, and the ratio of the powdered material was the highest. When the amount of the binder added was 5,10,20% by mass, it became easier to produce the half-split molded product, and the larger the amount of the binder added, the lower the proportion of the powdered material. When the amount of the binder added was 30% by mass, the half-split molded product was hardly produced, and the ratio of the completely molded product was the highest. From this, it can be seen that in order to efficiently produce the half-split molded product, the amount of the binder added should be 5% by mass or more and 20% by mass or less.

(Sintered pot test)
A complete or half-molded product produced when the linear pressure is 4 t / cm using the compounding raw materials (95% by mass fine powder ore and 5% by mass quicklime) used in the test in Table 1 above. Using, a sintering pot test was performed. The sinter pot test simulates the sinter process on a laboratory scale, and the sinter pot test allows for combustion front speed (FFS) and product yield and production of sinter. The rate and was measured.

In the sintering pot test, first, a cylindrical sintered pot having an arbitrary diameter and height was filled with a sintering raw material. Here, after setting the sinter (2.0 kg) as a sinter in a sinter pot, the sinter material was filled on the sinter. Then, the surface of the sintering raw material layer in the sintering pot was ignited, and air was sucked from the air box installed at the bottom of the sintering pot by a blower. This makes it possible to simulate the sintering process in the sintering raw material layer.

In this example, a sintered pan having a diameter of 300 mm and a height of 500 mm was used. Sintering was started by igniting the surface of the sintering raw material layer in the sintering pot with a burner for 1 minute while sucking air with a negative pressure of 9.8 kPa. The temperature of the exhaust gas was continuously measured by the temperature sensor installed in the air box, and the sintering was completed when 3 minutes had passed from the timing when the temperature of the exhaust gas reached the maximum value.

The compounding raw materials of the sinter and the compounding ratio (mass%) of each raw material are as shown in Table 3 below. As shown in Table 3 below, two sizes were prepared for the fully molded product and the half-split molded product. Specifically, as a complete molded product, a molded product having a major axis of 18,25 mm was prepared. Further, as the half-split molded product, a molded product obtained from a completely molded product having a major axis of 18,25 mm was prepared.

By using the cup of the molding roll 25a (internal volume 1.7 cm ³ ) used in the test of Table 1 above, a completely molded product having a major axis of 18 mm and a half-split molded product obtained from this completely molded product can be obtained. Manufactured. Further, by using a cup of a molding roll 25a (internal volume is 2.8 cm ³ ), a completely molded product having a major axis of 25 mm and a half-split molded product obtained from this completely molded product were manufactured.

The filling density of the sintered raw material in the sintered pot is a value obtained by dividing the weight of the sintered raw material filled in the sintered pot by the occupied volume of the sintered raw material in the sintered pot. The occupied volume of the sintered raw material is a value obtained by multiplying the layer thickness of the sintered raw material layer by the pot bottom area of the sintered pot.

In FFS, the layer thickness of the sintered raw material layer (size in the height direction of the sintered pot) when the sintered raw material is filled in the sintered pot is set, and the combustion zone is burned from the time when the ignition of the sintered raw material layer is started. It is a value divided by the time until the time when the bottom of the binder layer is reached (called the arrival time). In this embodiment, the arrival time is the rising time of the exhaust gas temperature.

The product yield of sinter was calculated as follows. After dropping the sintered cake from a height of 2.0 m four times, the dropped material was classified by a sieve (diameter 5 mm), and the weight of the bedding (2.0 kg) was subtracted from the weight on the sieve. The value was taken as the weight of the sinter. The product yield was obtained by dividing the weight of this sinter by the weight of the cake minus the weight of the bedding (2.0 kg).

The sintering time was defined as the time from the time when the ignition of the surface of the sintered raw material layer was started to the time when the temperature of the exhaust gas reached the maximum value. The production rate of sinter is a value obtained by dividing the weight of the sinter, which is a product, by the sinter time, and then dividing this division value by the pot bottom area of the sinter pot.

The results of the above-mentioned pot test are shown in Table 4 below.

In Example 1 (half-split molded product), the filling density was lower than that in Comparative Example 1 (completely molded product), and good air permeability was obtained, so that FFS was high. Further, in Example 1, the product yield and the production rate were higher than those in Comparative Example 1. Similarly, in Example 2 (half-split molded product), the packing density was lower than that in Comparative Example 2 (completely molded product), and good air permeability was obtained, so that FFS was high. Further, in Example 2, the product yield and the production rate were higher than those in Comparative Example 2.

Comparing Comparative Examples 1 and 2 having the same packing density, in Comparative Example 2, since the size of the completely molded product was larger than that in Comparative Example 1, the ventilation resistance could be reduced and the FFS increased. On the other hand, in Comparative Example 2, the product yield was significantly reduced as compared with the increase difference of FFS as compared with Comparative Example 1, and as a result, the production rate was lowered. The reason for this is that as the size of the fully molded product increases, the high temperature holding time during firing decreases as the FFS increases, and firing does not proceed sufficiently to the center of the fully molded product, producing a fragile fired body. It is thought that this is due to the fact.

Comparing Examples 1 and 2 having the same packing density, in Example 2, since the size of the half-split molded product was larger than that in Example 1, the ventilation resistance could be reduced and the FFS increased. On the other hand, unlike the relationship between Comparative Examples 1 and 2, in Example 2, the decrease in the product yield was suppressed as compared with the increase difference in FFS, and the production rate increased as a result. The reason for this is that by using the half-split molded product, the firing proceeds sufficiently to the inside of the half-split molded product as compared with the completely molded product as in Comparative Examples 1 and 2, and the decrease in the product yield is suppressed. It is thought that this was due to the fact that it was fired. Therefore, when a half-split molded product is used, it is considered that the larger the major axis of the completely molded product, which is the source of the half-split molded product, the higher the production rate.

11: Raw material tank, 12: Conveyor, 13: Drum granulator, 14: Conveyor, 21: Raw material tank,
22: Conveyor, 23: Stirring mixer, 24: Conveyor, 25: Compression molding machine,
25a: Molding roller, 26: Conveyor, 30: Sintering machine

Claims (4)

It is a method of manufacturing a molded product of a sintered raw material, which is charged into a sintering machine together with pseudo particles obtained by granulating the sintered raw material.
Using a compression molding machine for producing a complete molded product having a major axis of 15 to 30 mm, a sintered raw material containing 50% by mass or more of fine powder ore and 5 to 20% by mass of binder is compression-molded.
A method for producing a molded product, which comprises producing a half-split molded product to be charged into the sintering machine by causing a laminating phenomenon in the completely molded product by a compressive force of the compression molding machine. The method for producing a molded product according to claim 1, wherein the compressive force is a linear pressure of 4 t / cm or more. The method for producing a molded product according to claim 1 or 2, wherein the average particle size of the sintered raw material to be compression-molded is 1 mm or less. It is characterized in that the half-split molded product according to any one of claims 1 to 3 and the pseudo-particles obtained by granulating a sinter raw material are charged into a sinter to produce a sinter. How to make sinter.

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