JPH0257641A - Method of charging sintering raw material - Google Patents

Abstract

PURPOSE:To allow the use of a hardly sinterable iron ore and to reduce the production cost of the sintered ore by depositing raw materials for the sintered ore through a bar-shaped slant sieve so as to attain a specific grain size distribution in the thickness direction on the pallet of a sintering device at the time of producing the sintered ore for a blast furnace. CONSTITUTION:Quick lime is added to the powder of the iron ore which is not adequate as the raw material for the sintered ore such as easily metalble iron ore and hardly sinterable iron ore contg. SiO2 at a lower ratio and a carbonaceous material is added at need to form relatively rough minipellets 9 of 6-13mm grain size. The raw materials prepd. by adding and mixing auxiliary raw materials such as easily sinterable iron ore, returns of the sintered ore, carbonaceous material, and CaO to and with these pellets are put into a surge hopper 1. The powder raw material mixture is classified to fine grains 4a and coarse grains 4b by the primary sieve 3 arrayed obliquely with steel bars, etc. The grains are again classified by the bar-shaped secondary sieves 6a, 6b and are charged onto the pallet 7 of the sintering device so as to have the grain sizes gradually smaller from the lower layers to the upper layers to form a raw material packed layer 8. The front surface of the packed layer 8 is ignited by an ignition furnace 10 to sinter the raw materials. The use of the inexpensive sintering raw materials is possible and the cost of the sintered ore is reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a charging method that enables the use of raw materials with low sinterability when producing sintered ore used as a raw material for blast furnace charging. .

[Conventional technology]

When producing sintered ore from ironmaking raw materials such as fine ore, for example, iron ore with a particle size of 10 mm or less is mixed with coke of an appropriate particle size and, if necessary, auxiliary materials such as limestone powder, and this mixture is passed through a sintering machine. The coke is charged into a pallet, the coke on the surface layer is ignited, and the coke is combusted while sucking air downward, and the combustion heat generated at this time causes sintering. In such sintering, since the sintering reaction progresses due to the combustion of coke, the lower part of the raw material packed bed in the pallet becomes high temperature, increasing ventilation resistance. As a result, the sintering reaction becomes non-uniform in the thickness direction of the raw material layer, which tends to cause over-baking or insufficient sintering, and increases the proportion of sintered raw materials that are pulverized during transportation and handling.

In order to eliminate this drawback, the grain size of the sintering raw material charged into the pallet is coarse in the lower layer and finer in the upper layer.
In addition, various charging methods have been proposed so that the amount of coke is increased in the upper layer. The present inventors also developed a charging device that uses a sieve consisting of a plurality of rods arranged at an angle, classifies and charges sintering raw materials into pallets according to their particle size, and performs a uniform sintering reaction. Developed and patented in 1986-6
The application was filed as No. 4677.

However, some raw materials used as iron sources have poor sinterability, such as sintered raw materials and low S r 02 raw materials. For example, when sintering a low-SiO2 raw material, there is a shortage of slag bonds, resulting in a decrease in yield and strength. Attempts have been made to address such problems, and many proposals have been made. For example, Japanese Patent Application Laid-Open No. 59-9131 1
JP-A-59-83727.

JP-A No. 60-248827, etc., in which special raw materials are separated and fractionated to produce Cab, SiO□, and Mg.
Mini pellets are prepared in advance by mixing and granulating auxiliary raw materials such as O, and then the sintering compound raw materials are re-compounded, allowing special raw materials to be used without any problems. However, when the separated and granulated mini pellets are uniformly distributed in the blended raw materials, the specially formulated auxiliary raw materials are dispersed throughout, diluting the chance of reacting with only the special raw materials, and the effect is halved. .

Therefore, in Japanese Patent Publication No. 60-47887, a two-stage charging method is proposed in which mixed raw materials are charged into a pallet of a sintering machine so that the easily meltable ore is in the upper layer and the hardly meltable ore is in the lower layer. is proposed.

[Problem to be solved by the invention]

The two-stage charging method disclosed in the above publication involves transporting the raw materials for the upper layer and the raw materials for the lower layer in separate lines to the pallet of the sintering machine, and then transporting the refractory raw materials to the lower layer. Then, the easily soluble hostile raw material is charged on top of it. Therefore,
Two raw material transport systems are required, which increases the number of equipment installed. As a result, the equipment becomes complicated, maintenance and management become troublesome, and the burden of equipment costs increases. Compared to this drawback, the effectiveness of two-stage charging in actual operation is also diminished.

Therefore, the present invention utilizes classification charging using a sieve made up of a plurality of bars arranged at an angle, thereby eliminating the need for a plurality of independent raw material conveyance systems and eliminating the need for raw materials with poor sinterability. Pre-processed items are unevenly distributed in upper management,
The purpose is to undergo a uniform sintering reaction similar to other sintering raw materials, and to produce sintered ore with a high yield and eliminate quality problems.

[Means to solve the problem]

The present invention involves mixing and granulating easily melting sintering raw materials, hardly melting sintering raw materials such as low SiO2 raw materials, low melting point auxiliary raw materials such as CaO, and carbonaceous materials as necessary to obtain a particle size of 6 to 6. Coarse particles such as relatively coarse mini pellets of 13 m are mixed with ordinary raw materials such as easily sinterable raw materials, return ore, carbonaceous materials, and auxiliary raw materials and stored in a hopper. A primary sieve consisting of a plurality of rods is used to classify coarse grains and fine grains, and the particles are classified and stored in a coarse grain hopper and a fine grain hopper installed below the primary sieve, respectively. The fine-grained raw material from the fine-grain hopper is sorted by a secondary sieve consisting of a plurality of rods arranged at an angle, respectively, and the fine-grained raw material from the fine-grain hopper is loaded onto a sintering pallet so that the particle size gradually decreases from the lower layer to the upper layer. The coarse grain raw material from the coarse grain hopper is charged onto the raw material packed bed formed by the fine grain raw material to form a surface layer, and the coarse grain raw material is charged to the surface layer side so that the particle size gradually becomes smaller. This is a method for charging raw materials for sintering.

[Function] In the present invention, CaO is added to a specific raw material that is difficult to sinter.
After pretreatment such as detoxification treatment by adding a large amount of
It is mixed with other easily sinterable raw materials and conveyed on a pallet by a single transportation line, where it is passed through a primary sieve to a particle size (6 to 1
Separate the coarse mini-pellets that are differentiated by It is charged onto the raw material packed bed and is unevenly distributed only on the surface layer of the raw material packed bed. That is, the raw material packed bed thus formed is charged so that the lower layer is coarse and the grain size segregation becomes finer toward the middle and upper layers. As a result, the raw materials for sintering are segregated so that the particle size becomes finer from the bottom layer to the top layer, while in the top layer, only the specific raw materials that have been rendered harmless do not undergo the sintering reaction. A packed bed of raw materials is formed that is unevenly distributed in shape and is ideal in terms of ventilation and heat. As a result, a sintering operation with good efficiency, yield, and quality can be maintained even when H sintering raw materials are used.

Here, reference descriptions necessary for a deeper understanding of the operation of the present invention are shown below.

■ The present inventors, regarding porous and low SiO2 raw materials,
Index Rc-o= ((Ca0%-1,2XS102%)
/(Fe%)], by adjusting CaO so that 0.08≦RC, 0<0.25 for the blended raw materials excluding return ore, the low SiO2 raw material can be used without any problems. It has already been proposed. In the present invention, based on this principle, a large amount of CaO and low-SiO2 raw materials are made into mini pellets and rendered harmless.

■ The particle size of the mini pellets is set at 6 to 13IIffl, but this is to differentiate the mini pellets in terms of particle size among the sintering compound raw materials. For example, the particle size of the mini pellets is 6
~10mm is also acceptable. Although it is better to make the upper limit particle size of mini pellets as large as possible, it is determined by taking into consideration the practical particle size range for producing mini pellets when differentiating them from blended raw materials. The upper limit particle size of mini pellets is the maximum particle size of the blended raw materials +
1lnffl.

However, these do not require completeness.

■ It is inevitable that the mini-pellets themselves will disintegrate to some extent during the process in which the produced mini-pellets are recombined with the blended raw materials and transported. Since the actual effect is smaller than the originally expected effect due to the partial collapse of the mini-pellets, it is preferable to take this point into consideration in advance when determining the blended particle size.

〔Example〕

FIG. 1 is a flowchart showing an embodiment of the present invention.

For difficult-to-sinter raw materials such as easily soluble raw materials, low S+Oz raw materials, and high crystallization water-containing raw materials, a relatively large amount of CaO and carbonaceous materials are mixed with binder and return ore as shown in Part) I. Added. Then, while adding water to the blended raw materials, pseudo particles or mini pellets having a particle size of 6 to 13 mm are granulated using a pelletizer. The pseudo-particles or mini-pellets are transported to a classification/charging device via a raw material transport system.

On the other hand, the easily sinterable raw material is mixed with return ore, carbonaceous materials, auxiliary raw materials, miscellaneous raw materials, etc., as shown in part (2), and sent into the raw material transportation system from part (1) to the classification and charging device. and,
Mixed with the raw material from Part I, it is charged to the pallet of the sintering machine while being classified by particle size by a classifying and charging device.

As this classification and charging device, it is effective to use one in which sieves each consisting of a plurality of bars arranged at an angle are arranged in two stages as shown in FIG. That is, raw material 1, which is mainly composed of difficult-to-sinter raw materials from Part I,
It is mixed with raw materials mainly consisting of easily sinterable raw materials from II, stored in a surge hopper 1, and fed onto a primary sieve 3 from a drum feeder 2 provided at the bottom. By this primary sieve 3, the supplied raw material is classified into a fine part and a coarse part, and a fine part hopper 4a is used for each part.
and is accommodated in the coarse grain hopper 4b. At this time, the pseudo particles or mini pellets obtained in Par) 1 are sent to the coarse particle hopper 4b side because of their large particle size.

The fine grain and coarse grain materials stored in the hoppers 4a and 4b are transferred to a secondary sieve 6a for fine grains and a drum feeder 5b for fine grains and a drum feeder 5b for coarse grains provided at the bottom of the hoppers 4a and 4b, respectively. It is supplied to the secondary sieve 6b for coarse particles. With secondary sieves 6a and 6b,
The fine-grain raw material and the coarse-grain raw material are further classified and charged into a pallet 7 of the sintering machine.

The primary sieve 3 and the secondary sieves 6a and 6b are constructed by arranging a plurality of rods at an angle so that at least the lower side forms a mountain shape to form a sieve surface. This charging device itself was proposed in the above-mentioned Japanese Patent Application No. 5O-64677, and since the distance between the bars increases toward the tip (lower side) of the bars, Fine grains pass through the gaps between the bars on the side, and coarse grains pass between the bars on the tip side. Therefore, when the bars of the secondary sieves 5a and 5b are tilted so that the lower side of the bars is on the upstream side with respect to the traveling direction The packed bed 8 has particle size segregation in which the particle size decreases from the lower layer to the upper layer. Further, coke and the like are also charged in a state where they are segregated in the surface layer.

Since the raw material packed bed 8 is formed with such particle size segregation, as schematically shown in FIG. . And this pseudo particle or mini pellet 9
Because the material was prepared by mixing a difficult-to-sinter raw material with a large amount of CaO, the CaO content is locally high. In this way, since the difficult-to-sinter raw material exists together with a large amount of CaO at a relatively low temperature and well-ventilated area during sintering, the coke in the surface layer is ignited in the ignition furnace 10 and the raw material packed layer 8 is sintered. When performing sintering, the sintering of difficult-to-sinter raw materials also proceeds smoothly.

Here, ore A was used as a difficult-to-sinter raw material, and ore B was used as an easily sinterable raw material. The components and particle size distribution of ores A and B are shown in Table 1. To this hard-to-sinter raw material, 3% by weight of limestone (binder), 20% by weight of return ore, 35% by weight of carbonaceous material, and 15% by weight of limestone are added to prepare mini pellets with a particle size of 6 to 13 particles. did. On the other hand, the easily sinterable raw material is carbonaceous material, as in the past.

Mixed with return ore, auxiliary raw materials, etc. The above-mentioned mini pellets were mixed in a blended raw material mainly consisting of this easily sinterable raw material at a ratio of 20% by weight, and charged into the pallet 7 of the sintering machine using the classification charging device shown in Fig. 2. .

(Hereinafter, the margins of this page) Table 1 Table 2 When the raw material packed bed 8 thus formed was sintered to produce sintered ore, the product yield was 76.5%. Further, the reduction powdering index R111 was as low as 32.5%. On the other hand, when the difficult-to-sinter raw materials were charged into pallet 7 and sintered in the same proportions without being made into pseudo particles or mini pellets, the product yield was 75.
%, the powderization rate RDI was 36.6% (see Table 2)
. As is clear from this comparison, by charging the difficult-to-sinter raw material as pseudo particles or mini pellets containing a large amount of CaO, it became possible to use the difficult-to-sinter raw material as a sintering raw material.

〔Effect of the invention〕

As explained above, in the present invention, a difficult-to-sinter raw material is granulated together with a relatively large amount of CaO as pseudo particles or mini-pellets, mixed with an easily sinterable raw material, and loaded onto a pallet of a sintering machine. It's in. Therefore, a raw material packed layer in which CaO is unevenly distributed is formed around the difficult-to-sinter raw material, and the sintering reaction of the hard-to-sinter raw material is smoothly performed. As a result, it became possible to use an increased amount of N sinterable raw material, which was cheap and easy to obtain, but whose usage rate was limited due to poor sinterability.
Manufacturing costs can be reduced. Furthermore, since there is no need to carry out two-stage charging in which the raw material transportation system is completely two-lined as in the past, the equipment can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the flow of the charging method of the present invention, and the second
The figure shows an example of a charging device used in the present invention, and FIG. 3 is a diagram schematically showing a raw material filling bed charged into a pallet. 1: Surge hopper - 2, 5a, 5b Ni drum feeder 3rd secondary sieve 4a: Hot size for fine grains - 4b
: Hopper for coarse particles 6a, 6b: Secondary fluier: Pallet 8: Raw material packed bed 9: Pseudo particles or mini pellets 10: Ignition furnace

Claims (1)

[Claims] 1. Mix and granulate easily melting sintering raw materials, hardly melting sintering raw materials such as low SiO_2 raw materials, low melting point auxiliary raw materials such as CaO, and carbonaceous materials as necessary to obtain particles with a particle size of 6 to 13 mm. Coarse particles such as relatively coarse mini-pellets are mixed with ordinary raw materials such as easily sinterable raw materials, return ore, carbonaceous materials, and auxiliary raw materials and stored in a hopper. A primary sieve made of rods is used to classify coarse grains and fine grains, and the coarse grains and fine grains are classified and stored in a coarse grain hopper and a fine grain hopper installed below the primary sieve, respectively. The fine-grained raw material from the fine-grain hopper is classified by a secondary sieve consisting of a plurality of rods arranged at an angle, and then charged onto a sintering pallet so that the particle size gradually decreases from the lower layer to the upper layer. The coarse grain raw material from the coarse grain hopper is charged onto the raw material packed bed formed by the fine grain raw material to form a surface layer, and the coarse grain raw material is charged to the surface layer side so that the particle size gradually becomes smaller. Characteristic charging method of sintering raw materials.