JP6885386B2 - Manufacturing method of carbon material interior particles and manufacturing method of carbon material interior sintered ore - Google Patents

Description

The present invention relates to a technique for producing a sintered ore used as a raw material for iron making in a blast furnace or the like. The present invention relates to a method for producing a carbonaceous material interior sinter produced as a part of a raw material.

In the blast furnace ironmaking method, iron-containing raw materials such as sinter, iron ore, and pellets are mainly used as iron sources. Here, the sinter is a kind of agglomerate ore and is produced by the following procedure. First, from iron-containing raw materials such as iron ore and dust with a particle size of 10 mm or less, lime-containing raw materials such as limestone, fresh lime, and steelmaking slag, MgO-containing raw materials such as refined nickel slag, dolomite, and serpentine, and silica stone. An appropriate amount of water is added to a granulation raw material composed of a SiO _2- containing raw material and a coagulant made of powdered coke or smokeless coal, and the mixture is mixed and granulated using a drum mixer or the like to obtain pseudo-particles. Next, the granulated raw material made into pseudo particles is charged into a pallet that circulates and moves in the sintering machine, and the coagulant contained in the granulated raw material is burned to obtain a sintered cake. After that, the sintered cake is crushed, cooled, and sized, and those having a certain particle size or larger are recovered as a product sintered ore.

In the past, the main method was to uniformly sinter the entire sintered bed in liquid phase, but in recent years, as in the past, a portion mainly composed of liquid phase sintering and a portion in which liquid phase formation is suppressed are mixed in the sintered bed. However, a sintering method that aims at a non-uniform structure is being studied. The reason is that in the portion having a high melting point and being difficult to melt, many fine pores remain after firing, the contact area with the reducing gas increases, and a sintered ore structure that is easily reduced can be formed. ..

As a method for producing such agglomerate ore, Patent Document 1 describes wet pellets in which a carbonaceous material is coated with iron ore powder and a CaO-containing raw material as a method in which liquid phase formation is suppressed at a high melting point. A method of mixing with a sintering raw material mainly composed of liquid phase sintering and then sintering in a downward suction type sintering machine is disclosed.

Japanese Patent No. 5790966

As disclosed in Patent Document 1, in the carbonaceous material interior sinter, coal material interior particles having a carbonaceous material core are mixed with ordinary granulated particles having no carbon material core to be used as a sinter raw material and baked. Manufactured by sintering with a knot. However, if the carbonaceous material interior particles are granulated by the granulator and collapsed in the process of being transported to the sintering machine and charged, the portion where the liquid phase formation is suppressed is not generated and the sintering is easily reduced. It is not possible to form a mineral structure. The present invention has been made in view of the above problems, and an object of the present invention is to obtain carbonaceous material interior particles capable of suppressing the collapse of carbonaceous material interior particles in a process of being transported to a sintering machine and charged into the sintering machine. The purpose is to provide a manufacturing method.

The features of the present invention that can solve such a problem are as follows.
(1) A powdered iron-containing raw material, a lime-containing raw material, and cement powder are mixed to form a mixed powder.
A method for producing carbonaceous material interior particles, wherein the mixed powder and the carbonaceous material are granulated to produce carbonaceous material interior particles in which an outer layer made of the mixed powder is formed around a carbon material core.
(2) The method for producing charcoal interior particles according to (1), wherein the cement powder is blended so that the blending ratio of the cement powder to the mixed powder is 1% by mass or more and 10% by mass or less.
(3) A product obtained by mixing and granulating an iron-containing raw material, an auxiliary raw material, and a coagulant from the carbonaceous material interior particles produced by the method for producing the carbon material interior particles according to (1) or (2). A method for producing a sinter for interior sinter, in which the sinter is mixed with granules to form a sinter raw material, and the sinter raw material is charged into a pallet of a sinter and sintered.

By implementing the method for producing a carbon material interior sintered ore of the present invention, carbon material interior particles having high crushing strength can be produced, so that they collapse in the process of being transported to the sintering machine and charged into the sintering machine. The number of carbonaceous material interior particles can be reduced. Then, by sintering the sintering raw material containing the sinter interior particles to produce the sinter for the sinter, a sinter structure that is easily reduced to the sinter is formed, and the reduction efficiency is improved. it can.

It is a schematic diagram which shows an example of the manufacturing process 10 of the carbonaceous material interior particle which can carry out the manufacturing method of the carbonaceous material interior particle which concerns on this embodiment. It is a graph which shows the relationship between the mixing time in a kneader 28, and the crushing intensity distribution of the carbonaceous material interior particles granulated by a granulation machine 38. It is a photograph which shows the mixed powder 30, the coke particle 32 (including the growing carbonaceous material interior particle), and the carbonaceous material interior particle 40 existing in the granulation machine 38. It is a schematic diagram which shows an example of the manufacturing process 100 of the coal material interior sintered ore that can carry out the manufacturing method of the coal material interior sintered ore. It is a graph which shows the relationship between the curing period and the crushing strength of the carbonaceous material interior particles. It is a graph which shows the relationship between the blending ratio of cement powder, and the crushing strength of carbonaceous material interior particles. It is a graph which shows the relationship between the blending ratio of cement powder, and the porosity of the carbonaceous interior sintered ore. It is a graph which shows the RI of the sinter of an Example and a comparative example.

Hereinafter, the present invention will be described through embodiments of the present invention. FIG. 1 is a schematic view showing an example of a carbonaceous material interior particle manufacturing process 10 in which the method for producing carbonaceous material interior particles according to the present embodiment can be carried out. A method for producing the carbonaceous material interior particles according to the present embodiment will be described with reference to FIG.

In the production process 10 of the carbonaceous material interior particles, first, the iron ore powder 12 stored in the storage tank 14, the quicklime 16 stored in the storage tank 18, and the cement powder 20 stored in the storage tank 22 are stored respectively. A predetermined amount is cut out from the tank to the conveyor 24. The iron ore powder 12, quicklime 16 and cement powder 20 are transported by the transporter 24 to a kneader 28 such as an intensive mixer. The conveyed iron ore powder 12, quicklime 16 and cement powder 20 are mixed together with an appropriate amount of water 26 inside the kneader 28 to form a mixed powder 30.

In the present embodiment, the iron ore powder 12 is an example of a powdery iron-containing raw material, for example, ^{iron ore powder having a particle size of 150 μm or less and a specific surface area of about 1500 cm 2} / g, and dust and sludge generated in a steel mill. And so on. Quicklime 16 is an example of a lime-containing raw material, and limestone or slaked lime may be used instead of quicklime or together with quicklime. However, from the viewpoint of granulating the mixed powder 30, it is preferable to use quicklime or slaked lime having a high granulation effect. _{In addition, dolomite [CaMg (CO 3} ) ₂ ], which increases the viscosity of the melt produced during sintering, may be added to quicklime and / or limestone. That is, the lime-containing raw material is a raw material containing any one or more of quicklime, limestone and dolomite. The cement powder 20 is a hydraulic cement, such as Portland cement, mixed cement, and blast furnace slag cement. Since the cement powder 20 also contains quicklime, when the cement powder 20 is added, the amount of quicklime 16 cut out is reduced by the amount of the quicklime contained in the cement powder 20. In the following embodiment, Portland cement shown in Table 1 below was used as the cement powder 20. Although the long-term strength of cement varies depending on the type, the strength of the present invention may be as long as 4 weeks or less, and the long-term strength of several months is not required. Therefore, in this embodiment, any kind of cement can be used. In cold regions, it is more preferable to use alumina cement because the strength is developed in a shorter time.

In the kneading machine 28, it is preferable that each raw material is sufficiently mixed in the kneading machine 28 and each raw material is uniformly dispersed. Thereby, the quality of the carbonaceous material interior particles 40 can be stabilized. For example, if the dispersion of quicklime 16 becomes insufficient and the quicklime 16 is excessively blended in the carbon material interior particles in an amount higher than the set grade, the outer layer around the coal material core is melted in the subsequent sintering step, and the carbon material is used. Interior sintered ore may not be obtained. Further, if the dispersion of the cement powder 20 is insufficient and the amount of the cement powder 20 blended in the carbonaceous material interior particles is less than the set grade, sufficient strength to withstand handling such as transportation cannot be obtained, and the yield is low. It may decrease. Further, if the water 26 is not sufficiently dispersed, the granulation by the subsequent granulator 38 may be hindered.

FIG. 2 is a graph showing the relationship between the mixing time in the kneading machine 28 and the crushing intensity distribution of the carbonaceous material interior particles granulated by the granulating machine 38. In FIG. 2, the horizontal axis is the crushing strength (N / piece) of the carbonaceous material interior particles after 4 weeks of cement curing, and the vertical axis is the frequency (pieces). The dotted line in FIG. 2 shows the crushing of the carbonaceous interior particles after granulating the carbonaceous interior particles using the granulator 38 without mixing the raw materials with the kneader 28 and then performing the cement curing for 4 weeks. Shows the intensity distribution. The broken line indicates that the mixed powder obtained by mixing each raw material for 10 seconds with the kneader 28 is granulated into the carbonaceous interior particles using the granulator 38, and then cement-cured for 4 weeks. The distribution of crushing strength is shown. The solid line shows the mixture powder obtained by mixing each raw material for 60 seconds with the kneader 28, granulated into the carbonaceous interior particles using the granulator 38, and then cement-cured for 4 weeks. The distribution of crushing strength is shown. The mixing time when each raw material is continuously charged into the kneading machine 28 and the kneading is continuously performed can be calculated by dividing the retention amount of each raw material inside the kneading machine 28 by the charging speed. ..

As shown in FIG. 2, when no mixing was performed, the distribution width of the crushing strength became wide, and many relatively low-strength carbonaceous material interior particles were confirmed. When the mixing was performed for 10 seconds, the low-strength carbonaceous material interior particles were reduced as compared with the case where the mixing was not performed at all. When the mixing was carried out for 60 seconds, the low-strength carbonaceous material interior particles further decreased, the high-strength carbonaceous material interior particles increased, and the distribution width of the crushing strength became narrow. The mixed power at this time was 330 W / kg. The mixing power was calculated from the power consumption of the mixer divided by the mass of the mixture. The mixing energy when the mixing was carried out for 10 seconds was 3300 J / kg, and the mixed energy when the mixing was carried out for 60 seconds was 19,800 J / kg. From this result, it can be seen that by uniformly mixing each raw material with the kneader 28, the strength quality of the carbonaceous material interior particles is enhanced, the strength quality is made uniform, and the quality of the carbonaceous material interior particles can be stabilized. The mixing time at which each raw material can be sufficiently mixed is the mixing time and the distribution of crushing strength as shown in FIG. 2 using the raw materials used for producing the carbonaceous interior sintered ore, the kneader and the granulator. It can be determined by confirming the relationship.

Next, the mixed powder 30 mixed by the kneader 28 and the coke particles 32 stored in the storage tank 34 are cut out in a predetermined amount by the conveyor 36 and used as a raw material for granulation. In the present embodiment, the mixed powder 30 and the coke particles 32 are mixed so that the blending ratio of the coke particles 32 with respect to the granulation raw material is 1% by mass or more and 5% by mass or less, more preferably 2% by mass or more and 4% by mass or less. It is cut out.

In the present embodiment, the coke particles 32 are an example of a charcoal material, and the coke material has an outer layer made of a mixed powder 30 formed around the coke material to form a core of the charcoal material. Anthracite charcoal, Hongei charcoal, may be used as the charcoal material. Since coke particles and Hongei charcoal have low volatile content, the amount of combustion gas generated from the coal material during sintering can be reduced by using them, and the strength of the coal material interior sintered ore produced using the carbon material interior particles is reduced. Is suppressed. As a result, it is possible to suppress a decrease in the yield of the sinter for the interior of the carbonaceous material.

The granulation raw material is conveyed by the transfer machine 36 to a granulation machine 38 such as a disc pelletizer. The granulation raw material is rolled together with an appropriate amount of water 26 by the granulator 38, and the coke particles 32 become the carbon material core due to the cross-linking force of water or the like, and the outer layer composed of the mixed powder 30 is formed around the coke material interior. Particle 40 is produced.

FIG. 3 is a photograph showing the mixed powder 30, coke particles 32 (including growing carbonaceous material interior particles), and carbonaceous material interior particles 40 existing in the granulator 38. The carbonaceous material interior particles 40 are produced according to the production process 10 of the carbonaceous material interior particles shown in FIG. 1. However, if the strength of the carbon material interior particles 40 is low, the carbon material interior particles 40 are conveyed to the sintering machine and baked. It collapses in the process of being charged into the knot. Therefore, in the method for producing the carbonaceous material interior particles according to the present embodiment, the cement powder 20 is blended with the iron ore powder 12 and the quicklime 16. As a result, the strength of the mixed powder 30 formed as an outer layer around the coke particles 32 is increased, and it is possible to suppress the collapse of the carbonaceous material interior particles 40 in the process of transporting the mixed powder 30 to the sintering machine and charging the coke particles 32 into the sintering machine. ..

FIG. 4 is a schematic view showing an example of a production process 100 of a carbon material interior sinter in which a method for producing a carbon material interior sinter can be carried out. In the production process 100 of the carbon material interior sintered ore, in parallel with the production process 10 of the carbon material interior particles shown in FIG. 1, iron-containing raw materials such as iron ore and dust having a particle size of 10 mm or less, limestone, and fresh lime. , A raw material 50 containing an auxiliary raw material containing a CaO-containing raw material such as steelmaking slag and a coagulant made of powdered coke or smokeless charcoal having a particle size of less than 3 mm is granulated by a granulator 52 such as a drum mixer. Let it be a grain size. The auxiliary raw material may include an MgO-containing raw material such as refined nickel slag, dolomite, and serpentinite, and a SiO _2- containing raw material made of silica stone or the like.

Next, the carbonaceous material interior particles 40 are mixed with the granulated particles obtained by granulating the raw material 50 to obtain a sintered raw material. Of the sintering raw materials, the granulated particles obtained by granulating the raw material 50 serve as a portion mainly composed of liquid phase sintering, and the carbonaceous material interior particles 40 serve as a portion in which liquid phase formation is suppressed. It is preferable to add the carbonaceous material interior particles 40 to the granulated particles so that the mixing ratio of the carbonaceous material interior particles 40 with respect to the sintering raw material is 10% by mass or more and 30% by mass or less. As a result, the air permeability of the sinter raw material is improved, and the productivity of the carbonaceous interior sinter is improved.

The sintering raw material containing the carbonaceous material interior particles is carried into the surge hopper of the downward suction type sintering machine 60. The sintered raw material is charged from the surge hopper into an endlessly movable pallet to form an charged layer. The charge layer is ignited by an ignition furnace installed above, and the upper gas is sucked downward from the wind box installed below, so that the charge layer is sequentially burned and sintered. The charging layer is sintered by the heat of combustion generated by the combustion to form a sintered cake. The sintered cake is crushed and sized at the sinter part, and agglomerates having a particle size of 4 mm or more are recovered as a finished coal material interior sinter. The carbonaceous interior sintered ore produced in this way is used as a raw material for steelmaking in the blast furnace 70. The particle size in the present embodiment is a particle size obtained by sieving using a sieve having a nominal opening according to JIS (Japanese Industrial Standards) Z 8801-1, and for example, a particle size of 4 mm or more is defined as a particle size of 4 mm or more. The particle size that is sieved onto a sieve using a sieve with a nominal opening of 4 mm in accordance with JIS Z 8801-1.

The particle size of the coke particles 32 used in the method for producing the carbonaceous material interior particles according to the present embodiment is preferably 2 mm or more. By using coke particles having a particle size of 2 mm or more, it is possible to prevent the coke particles from disappearing in the step of sintering the sintering raw material containing the carbonaceous material interior particles with a sintering machine. The particle size of the coke particles 32 is more preferably 3 mm or more. By using a carbonaceous material having a particle size of 3 mm or more, the disappearance of coke particles can be further suppressed.

On the other hand, when coke particles having a large particle size are used, the amount of combustion gas generated from coke during sintering increases, and cracks occur in the outer layer covering the coke particles in the carbonaceous interior sintered ore. When the outer layer covering the coke particles is cracked, the strength of the carbonaceous interior sinter is greatly reduced, and as a result, the yield of the carbonaceous interior sinter is significantly reduced. Therefore, the particle size of the coke particles 32 is preferably 8 mm or less, and more preferably 6 mm or less.

Further, the particle size of the produced carbonaceous material interior particles 40 is preferably 8 mm or more and 18 mm or less. As described above, the carbonaceous interior sinter having a particle size of 4 mm or more is recovered as a product sinter, and the sinter having a particle size of less than 4 mm is recycled (returned) into a sintering raw material. Further, when the carbonaceous material interior particles 40 are sintered by a sintering machine, the volume becomes smaller due to evaporation of water or partial melting. Therefore, the particle size of the carbonaceous material interior particles 40 is preferably 8 mm or more, and more preferably 10 mm or more so that even if the carbonaceous material interior particles 40 are sintered as they are, they do not return ore.

On the other hand, if the thickness of the outer layer of the coke particles 32 formed on the carbon material interior particles 40 exceeds 5 mm, it becomes difficult to sinter all the outer layers of the carbon material interior particles 40 within a limited sintering time. Become. If a portion of insufficient sintering is present in the sinter for the interior of the carbonaceous material, the strength of the sinter for the interior of the carbonaceous material decreases, and the yield of the sinter for the interior of the carbon material decreases. Therefore, the thickness of the outer layer of the carbonaceous material interior particles 40 is preferably 5 mm or less. For example, the particles of the carbonaceous material interior particles when the particle size of the coke particles 32 is 8 mm and the thickness of the outer layer is 5 mm. The diameter will be 18 mm. Therefore, the particle size of the carbonaceous material interior particles 40 is preferably 18 mm or less.

In the method for producing carbon material interior particles according to the present embodiment, cement powder 20 is blended with the mixed powder to increase the strength of the carbon material interior particles 40 produced by the cement powder 20. Since cement powder is inexpensive, its production cost control effect is enhanced by using it in a mass production process such as the production of sinter.

Next, the strength of the carbonaceous material interior particles 40 will be described. From the time when the carbon material interior particles 40 are manufactured to the time when they are charged into the downward suction type sintering machine 60, the carbon material interior particles 40 transfer to a plurality of conveyors. Therefore, it is preferable that the carbonaceous material interior particles 40 have a strength to withstand the connection between a plurality of conveyors and the impact at the time of loading the pallet of the downward suction type sintering machine 60. First, the carbonaceous interior particles having different crushing strengths were experimentally produced, and the decay state of the carbonaceous interior particles after the transfer of the conveyor and the pallet loading was confirmed. As a result, by setting the crushing strength of the carbonaceous material interior particles to 9.8 N / piece or more, it can withstand the impact of connecting multiple conveyors and loading the pallet of the downward suction type sintering machine 60, and is a downward suction type. It has been found that direct delivery to the sintering machine 60 is possible. In the present embodiment, the crushing strength is the maximum strength measured by compressing the carbonaceous material interior particles at a compression rate of 1 mm / min using a compression tester.

In order to increase the crushing strength of the carbonaceous material interior particles to 9.8 N / piece or more, in the case of iron ore powder containing hematite as the main mineral, iron ore having a Braine ^{specific surface area of about 1800 to 2000 cm 2} / g or a particle size of 45 μm or less. It is necessary to use iron ore powder having a stone powder content of 80% by mass or more. However, most of the hematite concentrate fine powder currently distributed in the iron ore market has a Braine specific surface area of ^{about 500 to 1500 cm 2} / g and a content ratio of iron ore powder of about 45 μm or less of about 35 to 75% by mass. .. Therefore, even if these raw materials are used as they are, it is not possible to produce carbonaceous material interior particles having a crushing strength of 9.8 N / piece or more.

On the other hand, by crushing the iron ore powder using a ball mill or the like, ^{the content ratio of the iron ore powder having a Braine specific surface area of 1800 cm 2} / g or more or a particle size of 45 μm or less can be achieved of 80% by mass or more, but the equipment cost and running can be achieved. The cost is high. Therefore, in order to confirm whether or not the crushing strength of the carbon material interior particles can be increased to 9.8 N / piece or more by blending the cement powder 20 with the outer layer mixed powder 30 formed around the carbon material, FIG. 1 shows. The production test of the carbonaceous material interior particles was performed according to the production step 10 of the carbonaceous material interior particles shown.

The production test of the carbonaceous material interior particles was carried out according to the following procedure. First, iron ore powder having a particle size of 150 μm or less and a Braine specific surface area of 1500 cm ² / g, quicklime having a particle size of 75 μm or less, and cement powder having a particle size of 150 μm or less are mixed in a mass ratio of 95: 1: 4. And mixed uniformly using an intensive mixer to obtain a mixed powder. This mixed powder and coke particles having a particle size of 2 mm or more and 8 mm or less were mixed at a mass ratio of 98: 2 to prepare a granulation raw material. This granulation raw material was rolled using a disc pelletizer to granulate the granulation raw material, and carbon material inner particles in which an outer layer made of a mixed powder was formed around the carbon material were produced. The water required for granulation of the granulation raw material was supplied by spraying an appropriate amount into the intensive mixer and the disc pelletizer.

FIG. 5 is a graph showing the relationship between the curing period and the crushing strength of the carbonaceous material interior particles. In FIG. 5, the horizontal axis represents the curing period (Week), and the vertical axis represents the crushing strength (N / piece) of the carbonaceous material interior particles. Further, in FIG. 5, the values in parentheses indicate the water content ratio (mass%) of the carbonaceous material interior particles, the white circle plot shows the measured value of the crushing strength, and the black circle plot shows the average value of the crushing strength. As shown in FIG. 5, the crushing strength of the carbonaceous material interior particles became 9.8 N / piece or more within a few days after curing. It was also found that the curing period should be 3 weeks or more in order to achieve a crushing strength of 49 N / piece or more that does not collapse even when handled with a heavy machine or a reclaimer after curing.

From this result, ^{even when the iron ore powder having a specific surface area of less than 1800 cm 2} / g or a particle size of 45 μm or less and the content ratio of the iron ore powder of less than 80% by mass is used, the mixed powder containing the iron ore powder is used. It was confirmed that by blending the cement powder so that the blending ratio of the cement powder is 4% by mass, it is possible to produce the carbonaceous interior particles having a crushing strength of 9.8 N / piece or more. It was. On the other hand, when the cement powder was not blended, the crushing strength of the carbonaceous material interior particles was 2.0 to 3.9 N / piece, and the crushing strength could not be 9.8 N / piece or more.

Next, the mixing ratio of cement powder to the mixed raw material will be described. The carbonaceous material interior particles were produced by changing the mixing ratio of cement powder to the mixed raw material to 0 to 6% by mass, and the crushing strength of each carbon material internal particle was measured. When the mixing ratio of cement powder was increased, the mixing ratio of iron ore powder was reduced accordingly. FIG. 6 shows the measurement results of the crushing strength of the carbonaceous material interior particles.

FIG. 6 is a graph showing the relationship between the blending ratio of cement powder and the crushing strength of carbonaceous material interior particles. In FIG. 6, the horizontal axis is the mixing ratio (mass%) of the cement powder to the mixed powder, and the vertical axis is the crushing strength (N / piece) of the carbonaceous material interior particles after cement curing for 4 weeks. As shown in FIG. 6, the crushing strength of the carbonaceous material interior particles is improved by increasing the mixing ratio of the cement powder to the mixed powder. As shown in FIG. 6, if the blending ratio of the cement powder is 1% by mass or more, the crushing strength after 4 weeks becomes 25 N / piece. As shown in FIG. 5, since the strength after 3 days is about the strength after 4 weeks × 0.4, it can be seen that the crushing strength of 9.8 N / piece is obtained after 3 days.

Next, a sinter material containing carbonaceous material interior particles produced by changing the mixing ratio of cement powder to 0 to 12% by mass is used to produce a sinter material inside the material material, and the sinter is contained in each material material interior. The part derived from the carbonaceous material interior particles was extracted from. The porosity of the portion derived from the carbonaceous interior particles in the carbonaceous interior sintered ore was measured by the method specified in JIS R 1655: 2003. FIG. 7 shows the measurement results of the porosity of the portion derived from the carbon material interior particles in each coal material interior sintered ore.

FIG. 7 is a graph showing the relationship between the mixing ratio of cement powder and the porosity of the portion derived from the carbon material interior particles in the carbon material interior sintered ore. In FIG. 7, the horizontal axis is the mixing ratio (mass%) of the cement powder to the mixed powder, and the vertical axis is the porosity (%) of the portion derived from the carbon material interior particles in the carbon material interior sintered ore. .. As shown in FIG. 7, when the mixing ratio of the cement powder to the mixed powder is increased, the porosity of the portion derived from the carbon material interior particles in the carbon material interior sintered ore decreases. The higher the porosity of the portion derived from the coal material interior particles in the coal material interior sintered ore, the more advantageous the reduction reactivity in the blast furnace. Further, increasing the mixing ratio of the cement powder is not preferable because the slag content in the blast furnace raw material increases. Therefore, the blending ratio of the cement powder is preferably as low as possible, and from these facts, the blending ratio of the cement powder is preferably 10% by mass or less, and more preferably 6% by mass or less.

By increasing the mixing ratio of cement powder to the mixed powder, the crushing strength of the carbonaceous material interior particles can be increased. However, if the blending ratio of the cement powder is too high, the slag component of the carbonaceous material interior particles increases. Further, if the mixing ratio of the cement powder is too high, the precipitate formed by the hydration reaction between the cement powder and water closes the pores in the carbonaceous material interior particles, and the porosity of the carbonaceous material interior particles decreases. In order to suppress the increase of the slag component and secure a porosity of a certain level or more, the mixing ratio of the cement powder to the mixed powder is preferably 1% by mass or more and 10% by mass or less, and 1% by mass or more and 6% by mass or more. It is more preferable that it is as follows.

As described above, by implementing the method for producing the carbonaceous material interior particles according to the present embodiment, the carbonaceous material interior particles having high crushing strength can be produced at low cost, and the particles are transported to the sintering machine and are conveyed to the sintering machine. It is possible to reduce the amount of carbonaceous material interior particles that disintegrate in the process of being charged into the material. Then, by sintering the sintering raw material containing the sinter interior particles to produce the sinter interior sinter, many sinter structures that are easily reduced to the sinter are formed, and the sinter inside the sinter Improvement of ore reduction efficiency can be realized.

Further, even when iron ore powder having a specific surface area of ^{less than 1800 cm 2} / g or a particle size of 45 μm or less and an iron ore powder having a content of less than 80% by mass is used, the mixing ratio of cement powder to the mixed powder is 1. It was confirmed that by blending the cement powder so as to have a mass% or more and 10% by mass or less, it is possible to produce high-strength carbonaceous material interior particles that can be directly sent to the sintering machine.

Next, the result of confirming the reduction reactivity of the sinter for the interior of the carbonaceous material produced by sintering the sintering raw material containing the inner particles of the carbonaceous material will be described. FIG. 8 is a graph showing RI of sinters of Examples and Comparative Examples. RI is an index showing the reducibility of the sinter, and is a value measured in accordance with JIS M 8713.

In the comparative example shown in FIG. 8, it is simulated that the carbonaceous material interior particles collapsed in the process of transporting and charging the cement powder into the sintering machine without blending the cement powder, and the sintering raw material does not contain the carbonaceous material internal particles. Was charged into the sinter at a charging rate of 650 t / h to produce sinter. On the other hand, in the embodiment, assuming that the carbonaceous material interior particles do not collapse in the process of blending the cement powder, transporting the cement powder to the sintering machine, and charging the material, about 7% by mass (about 50 t / h) of the carbonaceous material interior particles are included. (Equivalent) The blended sintering raw material was charged into a sinter at a charging rate of 650 t / h to produce a sinter.

As shown in FIG. 8, it was confirmed that the RI of the carbonaceous interior sinter of the example was 3% higher than the RI of the sinter of the comparative example. From this result, by producing the carbonaceous material interior particles having high crushing strength by using the method for producing the carbonaceous material interior particles according to the present embodiment, the carbon material interior that collapses in the process of being transported to the sintering machine and charged. It can be seen that the number of particles can be reduced, and as a result, the reducibility of the sinter for the sinter produced from the sinter raw material containing the sinter for the sinter can be improved.

10 Manufacturing process of carbonaceous material interior particles 12 Iron ore powder 14 Storage tank 16 Fresh lime 18 Storage tank 20 Cement powder 22 Storage tank 24 Conveyor 26 Water 28 Kneader 30 Mixing powder 32 Coke particles 34 Storage tank 36 Conveyor 38 Granulation machine 40 Coal material interior particles 50 Raw material 52 Granulation machine 60 Downward suction type sintering machine 70 Blast furnace 100 Coal material interior sintered ore manufacturing process

Claims (2)

The powdered iron-containing raw material, the lime-containing raw material, and the cement powder are mixed to form a mixed powder.
Production of carbonaceous material interior particles by granulating the mixed powder and a carbonaceous material having a particle size of 8 mm or less to produce carbonaceous material interior particles in which an outer layer composed of the mixed powder is formed around a carbon material core. It ’s a method ,
A method for producing charcoal interior particles, wherein the cement powder is blended so that the blending ratio of the cement powder to the mixed powder is 1% by mass or more and 6% by mass or less. The carbonaceous material interior particles produced by the method for producing carbonaceous material interior particles according to claim 1 are mixed with an iron-containing raw material, an auxiliary raw material, and a coagulant, and mixed with the granulated granulated particles and fired. As a raw material
A method for producing a carbonaceous interior sinter, in which the sintering raw material is charged into a pallet of a sintering machine and sintered.

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