WO2011004907A1

WO2011004907A1 - Method for producing starting material for sintering

Info

Publication number: WO2011004907A1
Application number: PCT/JP2010/061856
Authority: WO
Inventors: 樋口隆英; 大山伸幸
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2009-07-10
Filing date: 2010-07-07
Publication date: 2011-01-13
Also published as: AU2010269436B2; JP2011032577A; AU2010269436A1; JP4840524B2; BR112012000638A2; BR112012000638B1; ZA201109441B; CN102482729B; CN102482729A

Abstract

Disclosed is a method for producing a starting material for sintering that allows for the efficient production of an excellent starting material even when using a disk pelletizer for pelletization. Sintering starting materials, other than the limestone-based and the solid fuel-based powder starting materials, are load into a drum mixer (1) for mixing and stirring, where said powder starting materials are mixed, and the resulting mixture is supplied to a disk pelletizer (2) and pelletized. The pellets obtained by pelletization are supplied along with the limestone-based powder starting material to a drum mixer (3) for outer layer formation. Then, the solid fuel-based powder starting material is added so that by the time that the pellets reach the discharge port of the drum mixer (3) for outer layer formation, a limestone-based powder starting material layer and a solid fuel-based powder starting material layer have formed by adhesion to the outer layer of the pellets. In this manner, in the adhering of the solid fuel-based powder starting material to the outermost layer of the pellets for sintering, which have been pelletized by the disc pelletizer (2), making it possible to reliably avoid uneven burning during sintering.

Description

Method for manufacturing raw materials for sintering

The present invention relates to a method for producing a sintering raw material for producing a sintered ore for a blast furnace using a downward suction droidoid type sintering machine.

Sinter ore used as a blast furnace raw material is generally manufactured through the following processing method of the sintered raw material. That is, first, iron ore having a particle size of 10 mm or less, and a SiO ₂ -containing raw material made of silica, serpentine, or nickel slag, and a limestone-based powder raw material containing CaO such as limestone, and a heat source such as powdered coke or anthracite Using a drum mixer, an appropriate amount of water is added and mixed and granulated to form a granulated product called granulated particles. The blended raw material consisting of this granulated material is charged onto a pallet of a Dwytroid type sintering machine so as to have an appropriate thickness, for example, 500 to 700 mm, and ignites the solid fuel in the surface layer portion. The solid fuel is combusted while sucking air toward the surface, and the sintered raw material blended by the combustion heat is sintered to form a sintered cake. The sintered cake is crushed and sized to obtain a sintered ore having a certain particle size or more. On the other hand, those having a particle size smaller than that are returned to ore and reused as a sintering raw material.

The reducibility of the sintered product ore manufactured in this way is a factor that greatly affects the operation of the blast furnace, as pointed out in the past. The reducibility of the sinter has a good negative correlation with the fuel ratio through the gas utilization rate in the blast furnace. When the reducibility of the sinter is improved, the fuel ratio in the blast furnace decreases. Further, the cold strength of the manufactured sintered product ore is also an important factor for ensuring the air permeability in the blast furnace, and each blast furnace is operated with a lower limit standard for the cold strength. Therefore, it can be said that the desired sintered ore for the blast furnace is excellent in reducibility and has high cold strength.

Therefore, it does not require enormous facilities as a pretreatment for the process of manufacturing sintered ore, and iron ore and SiO ₂ -containing raw materials are separated from limestone-based raw materials and solid fuel-based raw materials into granulated particles in stages. Thus, a sintered ore having a structure in which calcium ferrite (CF) having high strength is selectively formed on the lump surface, and hematite (He) having high reducibility is selectively formed toward the inside of the lump, As a method for producing a raw material for sintering capable of improving the cold strength and improving the reducibility of the sintered ore, the techniques relating to the following Patent Documents 1 to 3 have been completed.

Also, powder iron ore composed of fine iron ore and coarse iron ore, limestone and quicklime are mixed with a mixer, the mixture is granulated by adding water with a first pelletizer, and the granulated product is granulated. Production of a raw material for sintering called the so-called HPS (Hybrid Pelletized Sinter) method, which is sieved by a screen, and the top of the sieve is charged into a second pelletizer so that the surface of the granulated material is coated with powdered coke. A method has been proposed (see, for example, Patent Document 4).

Japanese Patent No. 3755452 Japanese Patent No. 3794332 Japanese Patent No. 3656632 Japanese Patent Publication No.2-4658

The method for producing a raw material for sintering described in Patent Document 4 uses a disk pelletizer for granulating the raw material for sintering. By using this disk pelletizer, an iron ore containing pellet feed that is fine powder is used. Stone can be granulated, and by combining this HPS method and the method for producing sintering raw materials described in Patent Documents 1 to 3, it is possible to granulate iron ore containing fine powder such as pellet feed Become.

However, in recent years, the price of iron ore raw materials has changed significantly from the beginning of development, and the composition of raw materials has also changed significantly. The processes described in Patent Documents 1 to 3 were originally developed for the purpose of expanding the use of pellet feed of fine iron ore (average particle size of 150 μm or less), which was inexpensive at that time, and improving the quality of sintered ore. However, since the price of fine iron ore has risen at present, the amount used has decreased, and the granulation strength in the pelletizer has decreased. Therefore, if the method for producing a raw material for sintering described in Patent Documents 1 to 3 is used as it is, the granulated particle diameter is kept small, the air permeability is poor, and uneven firing is likely to occur. It turns out that there is a need for improvement.
The present invention has been made paying attention to the above problems, and provides a method for producing a raw material for sintering capable of efficiently producing a good raw material even when a disk pelletizer is used for granulation. It is for the purpose.

In order to solve the above problems, a method for producing a raw material for sintering according to the present invention comprises preparing a sintered raw material comprising iron ore, a SiO ₂ -containing raw material, a limestone powder raw material, and a solid fuel powder raw material, and said iron ore. The SiO ₂ -containing raw material and the limestone powder raw material are mixed with a stirring and mixing drum mixer to produce a mixed raw material, and the mixed raw material is granulated with a disk pelletizer to produce granulated particles. The solid fuel system powder raw material is added to the granulated particles supplied to the outer layer formation drum mixer from the discharge port side of the outer layer formation drum mixer, and the solid fuel system is supplied to the outer layer formation drum mixer A solid fuel-based powder raw material layer is formed on the surface of the granulated particles during an external time of 10 seconds or longer from the addition of the powder raw material to the discharge from the outer layer forming drum mixer. It is.
In the method for producing a raw material for sintering, it is preferable that the exterior time is set to 40 seconds to 20 seconds.
Further, in the method for manufacturing a raw material for sintering, it is more preferable to set the exterior time to 30 seconds to 20 seconds.

Further, the method of producing a sintered material for the present invention, iron ore, SiO ₂ containing feedstock, to prepare a sintering material consisting of limestone-based powder materials and solid fuel-based powder materials, the iron ore and SiO ₂ containing feedstock Mixing with a stirring and mixing drum mixer to produce a mixed raw material, granulating the mixed raw material with a disk pelletizer, generating granulated particles, supplying the granulated particles to an outer layer forming drum mixer, and The limestone powder raw material is supplied to the forming drum mixer, and after the limestone powder raw material is supplied, the solid fuel powder raw material is added to the outer layer forming drum mixer, and the limestone powder raw material layer is formed on the granulated particles. And a solid fuel-based powder raw material layer is formed.

Further, in the method for producing a raw material for sintering, the supply of the limestone powder raw material is supplied from the charging side of the outer layer forming drum mixer, and the addition of the solid fuel powder raw material is performed in the outer layer It is preferable to add from the discharge port side of the forming drum mixer.
In the method for producing a raw material for sintering, the supply of the limestone powder raw material supplies the limestone powder raw material together with the granulated particles obtained by granulation with the disc pelletizer to the drum mixer for forming the outer layer. Preferably it consists of:

Further, in the method for producing a sintering raw material, the addition of the solid fuel-based powder raw material takes 40 seconds or less and 10 seconds or more from the addition of the solid fuel-based powder raw material to the discharge from the drum mixer for forming the outer layer. Preferably, the solid fuel-based powder raw material is added to the outer layer forming drum mixer. The exterior time is 40 seconds or less and more preferably 20 seconds or more.
Further, in the method for producing a raw material for sintering, the supply of the limestone powder raw material has an exterior time of 90 seconds or less from the supply of the limestone powder raw material to the discharge from the drum mixer for outer layer formation, In addition, the limestone powder raw material is supplied to the outer layer forming drum mixer so as to have an exterior time longer than the time from the addition of the solid fuel powder raw material to the discharge from the outer layer forming drum mixer. Is preferred.

A method of manufacturing a sintering material according to the present invention, iron ore, SiO ₂ containing feedstock, to prepare a sintering material consisting of limestone-based powder materials and solid fuel-based powder materials, the iron ore, SiO ₂ containing material and limestone Mixing the raw material powder with a drum mixer for stirring and mixing to produce a mixed raw material, granulating the mixed raw material with a disk pelletizer, generating granulated particles, and supplying the granulated particles to the drum mixer for forming the outer layer Then, the solid fuel powder material is added to the granulated particles supplied to the outer layer forming drum mixer from the outlet side of the outer layer forming drum mixer, and the solid fuel powder is applied to the surface of the granulated particles. Form the raw material layer, and set the exterior time from the addition of the solid fuel-based powder raw material to the discharge from the drum mixer for forming the outer layer as shorter as any of the granulated particle diameter, crushing strength, and granulated particle strength decreases. And it is characterized in and.

Further, the method for producing a sintered raw material according to the present invention comprises preparing a sintered raw material comprising iron ore, ultrafine ore, SiO ₂ containing raw material, limestone powder raw material and solid fuel powder raw material. Ore, SiO ₂ -containing raw material and limestone powder raw material are mixed with a drum mixer for stirring and mixing to produce a mixed raw material, the mixed raw material is granulated with a disk pelletizer to produce granulated particles, the granulated particles Is added to the outer layer forming drum mixer, and the solid fuel powder material is added to the granulated particles supplied to the outer layer forming drum mixer from the outlet side of the outer layer forming drum mixer, A solid fuel-based powder material layer is formed on the surface of the granulated particles during an exterior time of 30 seconds or more in 70 seconds or less from the addition of the system powder material to the discharge from the drum mixer for forming the outer layer. Is a thing
Moreover, in the said manufacturing method of the raw material for sintering, it is preferable that the said ultra-fine ore has an average particle diameter of 1 micrometer or more and 10 micrometers or less, and is 10 mass% or more and 60 mass% or less with respect to all iron ores.

Moreover, the method for producing a sintered raw material according to the present invention comprises preparing a sintered raw material consisting of iron ore, pellet feed, SiO ₂ -containing raw material, limestone powder raw material and solid fuel powder raw material, the iron ore, pellet feed, The raw material containing SiO ₂ and the limestone powder raw material are mixed with a drum mixer for stirring and mixing to produce a mixed raw material, the mixed raw material is granulated with a disk pelletizer to produce granulated particles, and the granulated particles are outer layered. The solid fuel powder is added to the granulated particles supplied to the forming drum mixer, and supplied to the outer layer forming drum mixer from the outlet side of the outer layer forming drum mixer, and the solid fuel powder A solid fuel-based powder raw material layer is formed on the surface of the granulated particles during the exterior time of 30 seconds or longer from the addition of the raw material to the discharge from the drum mixer for forming the outer layer. It is intended to.

Moreover, in the said manufacturing method of the raw material for sintering, it is preferable that the said pellet feed has an average particle diameter of -75 micrometers 70% or more, and is 10 mass% or more and 60 mass% or less with respect to all iron ores.
In the method for producing a sintering raw material, the outer layer forming drum mixer preferably has a residence time of 120 seconds or less. The residence time is more preferably 90 to 120 seconds.

Thus, according to the method for producing a raw material for sintering of the present invention, a limestone powder raw material is first formed on the surface of granulated particles granulated by a disk pelletizer, and then a solid fuel system such as powder coke is used. By forming and adhering the powder raw material, the solid fuel-based powder raw material adheres to the outermost layer of the granulated particles for sintering granulated by the disk pelletizer, which ensures the occurrence of uneven burning during sintering. I can stop.
Further, the average diameter of the granulated product can be optimized to improve the reducibility, and the yield can be reduced to improve the productivity.
In addition, the solid fuel-based powder raw material is added from the discharge port side of the outer layer forming drum mixer, and the outer packaging time from the addition of the solid fuel-based powder raw material to the discharge from the outer layer forming drum mixer is determined by the granulated particle diameter, crushing By setting the strength or granulated particle strength to be smaller, the shorter the setting, the coarse iron ore, the combination of coarse iron ore and ultrafine ore, the combination of coarse iron ore and pellet feed, etc. optimum granulation according to the iron ore raw material formulation can be performed.

It is explanatory drawing of one Embodiment of the manufacturing process with a disk pelletizer to which the manufacturing method of the raw material for sintering of this invention is applied. It is explanatory drawing which shows an example of the manufacturing process with a disk pelletizer which applied the manufacturing method of the conventional raw material for sintering. It is explanatory drawing of the test method of the manufacturing method of the raw material for sintering of this invention. It is explanatory drawing of the test result of FIG. It is explanatory drawing of the test method of the manufacturing method of the raw material for sintering of this invention. It is explanatory drawing of the test result of FIG. It is explanatory drawing of one Embodiment of the conventional granulated particle manufacturing process which abbreviate | omitted the disk pelletizer. It is explanatory drawing which shows the test result of other embodiment of this invention. FIG. 8 (a) is a diagram showing the relationship between the powder coke exterior time and the granulated average diameter, and FIG. 8 (b) is a diagram showing the relationship between the powder coke exterior time and the production rate. 8 (c) is a diagram showing the relationship between the crushing strength and the appropriate exterior time. It is a schematic diagram which shows granulated particle. Fig. 9 (a) is a schematic diagram of granulated particles when pellet feed is used and the powder coke exterior time is 90 seconds, and Fig. 9 (b) uses only pisolite ore, which is coarse iron ore. And it is a schematic diagram of granulated particles when the powder coke exterior time is 90 seconds. It is explanatory drawing which shows a wettability evaluation test. It is a characteristic diagram which shows the relationship between the time which evaluates wettability, and a rising water level height.

Next, an embodiment of a method for producing a raw material for sintering of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram of a manufacturing process with a disk pelletizer to which the method for manufacturing a raw material for sintering of the present embodiment is applied. Examples of the raw material manufacturing process (HPS method) for sintering with a disk pelletizer include those described in Japanese Patent No. 27488782 and Japanese Patent No. 2755036.
In FIG. 1, first, a sintering raw material made of iron ore, SiO ₂ -containing raw material, limestone-based powder raw material and fixed coke-based powder raw material is prepared. P feed is Pellet feed and B powder is Blending fine. Among the sintered raw materials, only the powdered coke that is the solid fuel-based powder raw material, or the sintered raw material excluding the powdered coke and the limestone that is the limestone-based powder raw material is supplied to the stirring drum mixer 1 and added water. And mixed with stirring to produce a mixed raw material.

The mixed raw material is supplied to the disk pelletizer 2 and granulated by the disk pelletizer 2 to generate granulated particles. The produced granulated particles are supplied to the outer layer forming drum mixer 3. In the outer layer forming drum mixer 3, an outer layer of limestone or powder coke is formed on the granulated particles granulated by the disk pelletizer 2. The raw material for sintering on which the outer layer is formed by the outer layer forming drum mixer 3 is charged into a downward suction dwytroid type sintering machine 4. In this dwy toroid type sintering machine 4, it is added to the powder coke of the raw material for sintering in the ignition furnace 5, and baking is performed. Here, the outer layer forming drum mixer 3 is provided with, for example, a powder coke projection device 6 that projects powder coke that is a solid fuel powder material from the outer discharge port side, and for example, a limestone powder from the charging side. A limestone projecting device 7 for projecting limestone as a raw material is provided. Both of the projection devices are constituted by, for example, a conveyor or a spray nozzle.

After the powder coke is ignited by the ignition furnace 5, the dwytroid sintering machine 4 is fired while conveying the raw materials for sintering by the conveyor while sucking from below with a blower. The sintered sintering raw material becomes a sintered cake. The sintered cake is crushed and sized, for example, a sintered ore having a particle size of 4 mm or more is supplied to a blast furnace, and the rest is returned to the iron ore. Reuse as a raw material for sintering equivalent to stone. Therefore, the iron ore in the sintering raw material described in the present invention will be described as including return ore.
FIG. 2 shows a conventional process for producing a raw material for sintering having a disk pelletizer 2 in the same manner as FIG. 1, in which powder coke, which is a solid fuel-based powder raw material, is projected from the charging side of the outer layer forming drum mixer 3. It is a manufacturing method. In this case, limestone, which is a limestone powder raw material, is charged from the stirring and mixing drum mixer 1.

The present inventor first conducted a test to find an optimum addition point of the powder coke which is a solid fuel-based powder raw material. FIG. 3 shows a test method. In the outer layer forming drum mixer (also referred to as a coating mixer) 3, the time required to form the powder coke layer on the surface layer of the granulated particles was determined. In addition, the length of the outer layer forming drum mixer 3 was set to 120 seconds or less after the raw material was charged until it was discharged. In other words, the drum mixer is a granulator, in which granulation is performed by rotation, but destruction and granulation are substantially repeated, and if the residence time is prolonged, the granulated particles themselves are destroyed. Therefore, the limit is set to 120 seconds or less, preferably 90 seconds or less.
The test is, for example, Australian coarse iron ore A (−8 mm), for example South American coarse iron ore B (−8 mm), iron ore B (−1 mm), quartzite powder, quicklime, return mineral, limestone, powder Coke is used as a sintered material, and these are blended at a weight ratio shown in Table 1 below.

Also, the test evaluated the relationship between the coke residence time in the drum mixer for forming the outer layer and the productivity, granulation property, and sinter quality. As a test level, an outer layer forming drum mixer 3 having a preferable residence time of 90 seconds was used, and a method of inserting powdered coke together with the granulated particle raw material from the charging side of the outer layer forming drum mixer 3 was tested as a conventional example. In addition, the relationship between the residence time in the drum mixer and the productivity was tested by changing the addition position of the powder coke. Table 2 below shows the residence time (exterior time) of the powder coke and the time for other granulation steps. Moreover, the production rate in each test, the average diameter of the granulated material, and the result of reducibility are shown in FIG.

From these results, the productivity improves when the residence time of the powder coke is shortened, and the condition for improving the productivity is when the powder coke residence time, that is, the exterior time is set to a range of 40 seconds or less and 10 seconds or more. The exterior time is preferably in the range of 40 seconds or less and 20 seconds or more, and more preferably, the exterior time is 30 seconds or less close to the peak in productivity and 20 seconds or more. This is because when the powder coke residence time exceeds 40 seconds, the destruction part of the granulated particle surface layer part and the powder coke mixed part are located in the granulated particle surface layer, and the productivity is hindered from the deterioration of the powder coke combustibility. Conceivable. Alternatively, the powdered coke is hydrophobic and poor in granulation as compared with other sintered raw materials. When the coke is retained together with the granulated particles in the outer layer forming drum mixer, it is granulated in the outer layer forming drum mixer. It is considered that this is because, in the disintegration process, the powder coke is embedded between the granulated particles, which causes the granulated particles to collapse and the granulated particle diameter tends to decrease.

Also, if the residence time after adding the powder coke, that is, the exterior time is shorter than 20 seconds, the collapse of the granulated particle diameter is suppressed, but the powder coke is not uniformly coated on the surface of the granulated particle, and the firing becomes uneven. When the productivity is somewhat reduced and the exterior time is shorter than 10 seconds, the powder coke is coated on the surface of the granulated particles, and the productivity is greatly reduced. Regarding reducibility, it became clear that the granulated particle size is increased and the ventilation is improved by shortening the powder coke exterior time, so that a high reducible calcium ferrite structure is generated by high temperature sintering. .

Next, using the optimum outer layer time for the outermost layer of the powder coke, limestone, which is a limestone powder raw material, was added to the outer layer forming drum mixer 3 using the test apparatus shown in FIG. The residence time of the powder coke, that is, the exterior time, was fixed at 30 seconds, which is the best mode, and the test was conducted by changing the residence time of the limestone, that is, the exterior time, in various ways. Table 3 below shows the residence times of the conventional example, the example, and the comparative example. FIG. 6 shows the results of firing time, yield, and production rate in each test.

In Patent Documents 1 to 3 described above, the external time of the powdered coke and limestone was said not to affect the productivity. However, in this embodiment granulated with a disk pelletizer, the external time of the limestone is set to be the same as that of the powdered coke. It turned out that it was necessary to set more than exterior time. That is, in Example 5 in which limestone is granulated by the disk pelletizer 2 and at the same time the outer layer forming drum mixer 3 is charged, as shown in FIG. 6, the firing time is longer than in the conventional example. , Yield and production rate are greatly improved. In Example 6 in which the exterior time of limestone is 60 seconds, the yield is further improved and the production rate reaches a peak. And, for example, as in Example 7, when limestone and powder coke are added at the same time, in the case of this embodiment granulated with a disk pelletizer, the yield improves with the exteriorization of limestone, and at the same time the powder coke Although the exterior state is slightly affected by the limestone and the production rate is lowered, the production rate equivalent to that of Example 5 in which the exterior time is 90 seconds can be ensured.

However, as in Comparative Example 2, when the exterior time of limestone is set to 10 seconds, which is shorter than the exterior time of powder coke, 30 seconds, the firing becomes uneven, the firing time increases, and the yield tends to decrease. Further, the production rate is further lowered to approach the conventional example, and the exterior effect of limestone cannot be enjoyed. For this reason, the range of 90 seconds, which is the exterior time of powdered coke, is a suitable range for the exterior time of limestone.

Thus, in the manufacturing method of the raw material for sintering of this embodiment, iron ore and SiO ₂ content are included as pretreatment of the process of manufacturing sintered ore for blast furnace by using the downward suction dwroid type sintering machine 4. Prepare raw material, sintering raw material consisting of limestone powder raw material and solid fuel powder raw material, mix iron ore excluding solid fuel powder raw material and SiO ₂ containing raw material with mixer 1 for stirring and mixing to produce mixed raw material Then, the produced mixed raw material is granulated using a disk pelletizer 2 to produce granulated particles, and the produced granulated particles are supplied to the drum mixer 3 for forming the outer layer, and the discharge port of the drum mixer 3 for forming the outer layer The exterior time from the addition of the solid fuel-based powder raw material to the outlet of the drum mixer 3 for forming the outer layer is set in the range of 40 seconds or less and 10 seconds or more. Solid fuel system powder field To adhere and form a layer. Alternatively, among the sintered raw materials, the sintered raw materials excluding the limestone powder raw material and the solid fuel-based powder raw material are charged and mixed into the drum mixer 1 for stirring and mixing, and the mixed raw material is supplied to the disk pelletizer 2 for granulation. At the same time, the granulated particles obtained by granulation are supplied to the drum mixer 3 for forming the outer layer, the limestone powder material is added to the drum mixer 3 for forming the outer layer, and then the solid fuel powder material is added to the outer layer. The granulated particles granulated by the disk pelletizer 2 by adhering and forming a limestone powder raw material layer and a solid fuel powder raw material layer on the outer layer of the granulated particles while reaching the discharge port of the forming drum mixer 3 First, a limestone powder raw material is adhered and formed on the surface, and then a solid fuel-based powder raw material such as powder coke is adhered and formed on the outermost layer of the granulated particles for sintering granulated by the disk pelletizer 2 Solid Will be fuel based flour material is attached, it can be reliably prevented uneven burning occurs during sintering.

Further, by adding the limestone powder material from the charging side of the outer layer forming drum mixer 3 and adding the solid fuel powder material from the outlet side of the outer layer forming drum mixer 3, the granulated particles for sintering are added. The solid fuel-based powder raw material is reliably attached to the outermost layer.
Further, by introducing the limestone powder raw material into the outer layer forming drum mixer 3 together with the granulated particles obtained by granulating with the disk pelletizer 2, uneven burning is prevented and the productivity is improved.

In addition, the outer layer forming drum mixer 3 arranged in the subsequent process of the disk pelletizer 2 has a drum mixer length of 120 seconds or less for the charging raw material, or the outer layer forming drum arranged in the subsequent process of the disk pelletizer 2. The addition of the solid fuel powder material to the drum mixer 3 can improve the reducibility by optimizing the average diameter of the granulated product by setting the residence time to 40 seconds or less, and further reducing the yield. And productivity can be improved.

Moreover, although the said embodiment demonstrated the case where it granulated with the disk pelletizer 2 using only a coarse-grained iron ore, it is not limited to this and is averaged in two types of coarse-grained iron ores A and B When ultrafine ore with a particle size of 1 μm or more and 10 μm or less is added in the range of 10 mass% to 60 mass% of the total iron ore, preferably in the range of 30 mass% or less and 10% or more, two kinds of coarse iron ores A and B The same test as described above was performed when a pellet feed containing 70 mass% or more of an average particle size of −75 μm was added in the range of 10 mass% to 60 mass% of the total iron ore, preferably 60 mass%.
In this test, each brand and weight ratio are blended as shown in Table 4 below, and the test conditions are shown in Table 5 below.

Here, the test condition No. 1 is an example in which coarse Australian ore and South American iron ore are blended 50% each as iron ore as in the previous example, and the HPS method shown in FIG. 3 is applied as the granulation process. is there. Test condition No. 2 is the above-mentioned No.2. 1 is a conventional example using the same iron ore as in No. 1 and applying the DL method shown in FIG. 7 as a granulation process.

Also, test condition No. No. 3 is composed of 45% coarse iron ore and South American iron ore as iron ore, and 10% ultrafine ore with an average particle size of 10μm. 3 is an example to which the HPS method shown in FIG. 3 is applied. Test condition No. 4. As iron ore, 20% each of coarse Australian iron ore and South American iron ore was added to each 60%, and the pellet feed containing 70% or more of the average particle size of −75 μm was blended 60%. It is the Example which applied the HPS method shown in FIG. 3 as a process.

These test conditions No. 1-No. The test results for 4 are shown in FIGS. 8A is a diagram showing the relationship between the powder coke exterior time and the granulated particle diameter. For No. 1 to No. 3, the left granulated particle diameter is applied, and test conditions No. 1 to No. 3 are applied. For No. 4, the right granulated particle size is applied. 8B is a diagram showing the relationship between the powder coke exterior time and the production rate, and FIG. 8C is a diagram showing the relationship between the crushing strength (kg / P) and the appropriate exterior time (s). It is.

From this experimental result, as shown in FIG. No. 2 has the smallest granulated particle size. 1, no. 3 and no. The granulated particle diameter increases in the order of 4. Here, the test condition No. 1 and no. 3, the granulated particle diameter increases as the powder coke exterior time becomes shorter than 90 seconds. For No. 4, the granulated particle size is about 2 to 3 times larger than other test conditions, and there is no increase in the granulated particle size even if the powder coke exterior time is shortened from 90 seconds. .About the same value of around 5 mm.

And as apparent in FIG. 8 (b) showing the relationship between the powder coke exterior time and the production rate, the test condition No. The production rate of No. 4 is the highest in the range where the powder coke exterior time is 90 or less and 30 seconds or more, and when the powder coke exterior time is longer than 90 seconds or shorter than 30 seconds, the production rate decreases.
In addition, the test condition No. As shown in FIG. 8 (b), the production rate of No. 3 becomes the largest in the range of 30 seconds or more when the powder coke exterior time is 70 seconds or less, and the powder coke exterior time becomes longer than 70 seconds or from 30 seconds. As it gets shorter, the production rate decreases.

Furthermore, test conditions No. 2 with the next largest granulated particle size. As shown in FIG. 8 (b), the production rate of 4 is the largest in the range of 20 seconds or more when the powder coke exterior time is 40 seconds or less, and the powder coke exterior time is longer than 40 seconds or more than 20 seconds. As it gets shorter, the production rate decreases.
From the above results, it was found that the longest time of the powder coke coating time needs to be set shorter as the granulated particle diameter becomes smaller from the larger granulated particle diameter.

Further, in the relationship between the crushing strength (kg / P) and the appropriate exterior time (s) of the powder coke, as shown in FIG. In No. 4, the proper exterior time is 90 seconds, and the test condition No. 3 has an appropriate exterior time of 70 seconds, and the test condition No. In 1, the appropriate exterior time is 30 seconds.
From this test result, it was found that it was necessary to set the powder coke exterior time shorter as the crushing strength decreased from a larger value to a smaller value.

As described above, the granulated particles of iron ore are mixed with the powdered coke in the mixer and grow while repeating adhesion and collapse. Australian iron ore such as pisolite ore is coarser than pellet feed, and the strength of iron ore granulated particles decreases. Moreover, since powder coke is hydrophobic, when mixed inside the granulated particles, the strength of the granulated particles decreases. That is, it is necessary to shorten the powder coke exterior time in order to suppress the penetration and collapse of the powder coke into the particles.

The granulated particle strength σ (N) of the granulated particles can be expressed by the following formula (1).
σ = 6 · ψ · S · {(1-ε) / ε)} · (γcos θ / d) (1)
Where ψ is the degree of liquid fullness (−), S is the surface area of the powder (m ² ), ε is the porosity of the granulated product (−), γ is the surface tension of water (N / m), and θ is The contact angle (°), d is a specific surface area sphere equivalent diameter (m).
When the pellet coke exterior time is 90 seconds using pellet feed, the mixture of pellet feed and limestone is around the core ore 21 as schematically shown in FIG. 9 (a). The particle structure is covered and the hydrophobic powder coke 23 adheres to the outer layer of the mixture 22. The granulated particle strength σ in this case is σ = 6.8 × 10 ⁻³ N.

On the other hand, when only the pisolite ore, which is a coarse iron ore, is used and the powder coke exterior time is 90 seconds, the hydrophobic ore coke 23 around the core ore 21 becomes the pisolite ore 24. It becomes a mixed state. The granulated particle strength σ in this case is σ = 8.4 × 10 ⁻⁴ N, which is one order of magnitude smaller than when pellet feed is used.
In addition, the wettability of iron ore, limestone and powder coke was evaluated from the rate of water rise in the powder packed bed by applying a capillary method. In this evaluation test, as shown in FIG. 10, a container filled with water in a state where a glass tube 31 having a diameter of 25φ with a gauze 30 at the lower end is filled with powdered coke, limestone, and iron ore, respectively. The gauze part was immersed in 32, and the height of the rising water level per unit time was measured.

As shown in FIG. 11, the relationship between time √t (s ^1/2 ) and the rising water level height (mm) as a result of the measurement is as follows. Iron ore (contact angle θ = 45 °) and limestone (contact angle θ = 55 °), the rising water level increases approximately in proportion to the increase of time √t, but the powder coke (contact angle θ = 84 °) is about half the rising water level of iron ore and limestone. Yes, wettability is poor compared to iron ore and limestone. For this reason, when the powder coke penetrates into the pseudo particles, the particle strength decreases and the granulated particle diameter decreases.

In addition, as an evaluation formula of wettability, there is a Hagen-Poiseille equation of the following equation (2).
H = √ {(φdγcosθ / 2η) t} (2)
Here, H is the rising water level (m), t is time (s), θ is the contact angle (°), η is the viscosity of water (N · s / m ² ), γ is the surface tension (N / m), d is the particle size (m), and φ is the shape factor (−).

Therefore, in order to increase the granulated particle size and ensure the particle strength, it is necessary to suppress the intrusion of powder coke into the granulated particles, and ultrafine powder or pellet feed is mixed into coarse iron ore. When the granulated particle strength is low with only coarse iron ore compared to the case where the granulated particle strength is increased, it is necessary to reduce the external packaging time of the powdered coke, and the granulated particle strength is reduced. As a result, the powder coke exterior time is set shorter.

1 is a stirring mixer drum mixer, 2 is a disk pelletizer, 3 is a drum mixer for outer layer formation, 4 is a droidoid sintering machine, 5 is an ignition furnace, 6 is a powder coke projection device, and 7 is a limestone projection device

Claims

Prepare a sintering raw material consisting of iron ore, SiO 2 containing raw material, limestone powder raw material and solid fuel powder raw material,
The iron ore, SiO 2 containing raw material and limestone powder raw material are mixed with a drum mixer for stirring and mixing to produce a mixed raw material,
The mixed raw material is granulated with a disk pelletizer to produce granulated particles,
Supplying the granulated particles to a drum mixer for outer layer formation;
The solid fuel powder material is added to the granulated particles supplied to the outer layer formation drum mixer from the outlet side of the outer layer formation drum mixer, and the outer layer formation drum is added from the addition of the solid fuel powder material. A method for producing a raw material for sintering, comprising: forming a solid fuel-based powder raw material layer on the surface of the granulated particles during an exterior time of 10 seconds or longer and 40 seconds or less until discharging from the mixer.
The method for manufacturing a raw material for sintering according to claim 1, wherein the exterior time is 40 seconds or less and 20 seconds or more.
The method for producing a sintering raw material according to claim 2, wherein the exterior time is 30 seconds or less and 20 seconds or more.
Prepare a sintering raw material consisting of iron ore, SiO 2 containing raw material, limestone powder raw material and solid fuel powder raw material,
Mixing the iron ore and the SiO 2 -containing material with a drum mixer for stirring and mixing to produce a mixed material,
The mixed raw material is granulated with a disk pelletizer to produce granulated particles,
Supplying the granulated particles to a drum mixer for outer layer formation;
The limestone powder raw material is supplied to the outer layer forming drum mixer, and after the supply of the limestone powder raw material, the solid fuel powder raw material is added to the outer layer forming drum mixer, and the limestone powder is formed on the granulated particles. A method for producing a raw material for sintering, comprising forming a raw material layer and a solid fuel-based powder raw material layer.
The supply of the limestone powder raw material consists of supplying from the charging side of the drum mixer for forming the outer layer,
The method for producing a raw material for sintering according to claim 4, wherein the addition of the solid fuel-based powder raw material is performed from the discharge port side of the outer layer forming drum mixer.
5. The supply of the limestone powder raw material comprises supplying the limestone powder raw material together with the granulated particles obtained by granulation with the disk pelletizer to the drum mixer for forming the outer layer. The manufacturing method of the raw material for sintering as described in 2.
In the outer layer forming drum mixer, the addition of the solid fuel-based powder raw material has an exterior time of 10 seconds or more in 40 seconds or less from the addition of the solid fuel-based powder raw material to the discharge from the outer layer forming drum mixer. The method for producing a sintering raw material according to claim 4, comprising adding the solid fuel-based powder raw material.
The method for producing a raw material for sintering according to claim 7, wherein the exterior time is 40 seconds or less and 20 seconds or more.
The supply of the limestone powder raw material has an exterior time of 90 seconds or less from the supply of the limestone powder raw material to the discharge from the drum mixer for forming the outer layer, and the outer layer formation from the addition of the solid fuel powder raw material. The limestone powder raw material is supplied to the outer layer forming drum mixer so as to have an exterior time equal to or longer than the time until discharge from the drum mixer for use in sintering. Raw material manufacturing method.
Prepare a sintering raw material consisting of iron ore, SiO 2 containing raw material, limestone powder raw material and solid fuel powder raw material,
The iron ore, SiO 2 containing raw material and limestone powder raw material are mixed with a drum mixer for stirring and mixing to produce a mixed raw material,
The mixed raw material is granulated with a disk pelletizer to produce granulated particles,
Supplying the granulated particles to a drum mixer for outer layer formation;
The solid fuel powder raw material layer is added to the granulated particles supplied to the outer layer forming drum mixer from the outlet side of the outer layer forming drum mixer, and the solid fuel powder raw material layer is formed on the surface of the granulated particles. Form the
The firing time from the addition of the solid fuel-based powder raw material to the discharge from the outer layer forming drum mixer is set to be shorter as any one of the granulated particle diameter, crushing strength, and granulated particle strength decreases. A method for producing a ligation raw material.
Prepare a sintered raw material consisting of iron ore, ultrafine ore, SiO 2 containing raw material, limestone powder raw material and solid fuel powder raw material,
The iron ore, ultrafine ore, SiO 2 containing raw material and limestone powder raw material are mixed with a stirring and mixing drum mixer to produce a mixed raw material,
The mixed raw material is granulated with a disk pelletizer to produce granulated particles,
Supplying the granulated particles to a drum mixer for outer layer formation;
The solid fuel powder material is added to the granulated particles supplied to the outer layer formation drum mixer from the outlet side of the outer layer formation drum mixer, and the outer layer formation drum is added from the addition of the solid fuel powder material. A method for producing a raw material for sintering, comprising forming a solid fuel-based powder raw material layer on the surface of the granulated particles during an exterior time of 70 seconds or less until discharge from the mixer and 30 seconds or more.
The raw material for sintering according to claim 11, wherein the ultrafine ore has an average particle size of 1 µm or more and 10 µm or less, and 10 mass% or more and 60 mass% or less with respect to the total iron ore. Method.
Prepare a sintered raw material consisting of iron ore, pellet feed, SiO 2 containing raw material, limestone powder raw material and solid fuel powder raw material,
The iron ore, pellet feed, SiO 2 containing raw material and limestone powder raw material are mixed with a stirring and mixing drum mixer to produce a mixed raw material,
The mixed raw material is granulated with a disk pelletizer to produce granulated particles,
Supplying the granulated particles to a drum mixer for outer layer formation;
The solid fuel powder material is added to the granulated particles supplied to the outer layer formation drum mixer from the outlet side of the outer layer formation drum mixer, and the outer layer formation drum is added from the addition of the solid fuel powder material. A method for producing a raw material for sintering, characterized in that a solid fuel-based powder raw material layer is formed on the surface of the granulated particles during an exterior time of 90 seconds or less until discharge from the mixer and 30 seconds or more.
The method for producing a raw material for sintering according to claim 11, wherein the pellet feed has an average particle diameter of −75 μm of 70% or more and 10 mass% or more and 60 mass% or less with respect to the total iron ore. .
The method for producing a raw material for sintering according to any one of claims 1 to 14, wherein the drum mixer for forming an outer layer has a residence time of 120 seconds or less.
The method for producing a raw material for sintering according to claim 15, wherein the residence time is 90 seconds or more and 120 seconds or less.