JPS61170523A - Treatment of sintering raw material - Google Patents

Abstract

PURPOSE:To optimize the constitution of the grain size of a charging raw material and to improve the productivity of a sintering machine by specifying the ratio of the wet particles which are formed by pelletizing part of pulverized ore to a prescribed grain size range with the particles having the prescribed grain size range below said range and charging such ore to a pelletizer. CONSTITUTION:The pulverized ore f1-fn of various brands unloaded from a ship 1 are piled in a crude ore yard 2 and are thereafter classifies to plural groups by grain sizes and are blended by each of the brand groups of the pulverized ore. Here the pulverized ore f1-fn-2 are stacked 3a as the coarse powder and the pulverized ore fn-1, fn are stacked 3b as pulverous powder. These powders are mixed at a specific ratio and are separately charged together with raw materials for limestone, pulverized coke and return fins to blending tanks 4. The raw materials are fed out continuously at prescribed ratios from the tanks 4 and are blended. The blended materials are fed to a primary mixer 5. On the other hand, part of the deposited 3b pulverous powder is preliminarily pelletized 21 to manufacture particles forming 1.0-5.0mm and the particles are fed to the mixer 5. The wet particles having the above-mentioned grain size range out of the pulverized ore of the mixer 5 are controlled to 50-70% of the entire weight including the wet particles having <=0.5mm grain size to improve the air permeability on a sintering machine 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for treating sintered raw materials that is an improved pretreatment method for sintered raw materials.

(Prior art and its problems) FIG. 1 shows a general processing method for pre-processing fine ore to produce sintered ore, which is a raw material for a blast furnace. In this method, firstly, each brand of fine ore unloaded from ship 1 /1~/n
is piled up in rough ore yard 2. Next, these fine ore f1
~/, are buried in a layered manner in the blending yard 3, and mixed in a preset ratio by the pecking method to obtain a blending powder (hereinafter referred to as B powder). Next, the B powder is charged into separate mixing tanks 4 together with each raw material such as limestone, coke powder, and return ore. A predetermined amount of each raw material is continuously cut out from each blending tank 4 and blended, sent to a primary mixer 5 for water addition and granulation, and, if necessary, water addition and granulation in a secondary mixer 6. The raw material granulated in this way (hereinafter referred to as pseudo particles) is transferred from the hot plate 47 to the sintering machine 8 and continuously charged to the hot plate 9, and the coke powder mixed in the raw material is transferred to the ignition furnace. 10 is used to ignite the sintered ore, and sintered ore is produced by forcibly suctioning and ventilating it from the wind box 11 installed below the sintering machine.

However, with this method, it is not possible to make arbitrary selections because the brand of fine ore must be selected and blended from among the incoming fine ores. The chemical composition of the rounding is determined preferentially, but the particle size is not at all arbitrary, at most the upper limit of the blending amount of powder ore brands with fine particles unsuitable for granulation is controlled. Therefore, in the drum type granulator, it is not possible to maintain the particle size structure of the charged raw material, although it is necessary to granulate strong pseudo-particles with sufficient adhesion of fine powder. For this reason, the resulting pseudo particles cannot be made optimally, and as a result, the permeability of the raw material on the sintering machine is poor and the productivity is low.

Many proposals have been made to date to solve these problems. For example, a commonly known method is to add a granulation accelerator such as quicklime or slaked lime to obtain pseudo particles with excellent air permeability. However, since quicklime, slaked lime, etc. are more expensive than the limestone that is usually mixed, there is a problem in that the manufacturing cost becomes high. For this reason, a method has been proposed in which hot water is added as water during granulation to promote the granulation effect of quicklime.
-38494). However, this method still has the problem of high manufacturing costs.

On the other hand, methods using fine powder raw materials include, for example, the Foreverette method and the Semi-Bellet method.

The Foreverette method is a method in which all sintering raw materials are granulated using a drum-type or dish-type granulator, and then charged into a sintering machine. In addition, in the semi-pellet method, fine powder raw materials and powder raw materials containing some coarse particles are pulverized by a granulator.
This is a method in which a small spherical raw pellet of about 10 m in length is formed, which is mixed with flour ore and powder raw material and fed to a sintering machine.

The 7-or-bere method is a method that is used in many steel mills using drum-type granulators, but even now that primary and secondary mixers are installed, the resulting pseudo-particles do not have sufficient adhesion of fine powder. Moreover, it does not have sufficient strength. For this reason, it is possible to install a tertiary mixer, but this increases the equipment cost.

On the other hand, the semi-pellet method does not take into consideration the fine powder present in raw materials other than fine powder raw materials, that is, raw materials that have not been semi-pelletized, so it improves the air permeability of the raw materials on the sintering machine, and There are limits to productivity improvement. Furthermore, as an improvement to the semi-pellet method, there is a method disclosed in Japanese Patent Publication No. 39-1801. This method is a combination of the semi-pellet method and the fore pellet method, in which the semi-pelletized raw material and the non-semi-pelletized raw material are further charged into a granulator to strengthen the granulation. It is. This method is very effective, but since it is necessary to semi-pelletize the entire amount of fine powder raw materials and powder raw materials containing some coarse particles, it requires a large amount of fine powder raw materials to be processed. Under certain circumstances, an increase in equipment costs is unavoidable.

(Technical Problem of the Invention) The present invention has been made in view of the above circumstances, and its purpose is to adjust the particle size composition of the charged raw material in a drum-type granulator to an appropriate range by a simple method, and to The present invention aims to provide a method for processing sintering raw materials that can improve the permeability on the sintering machine and increase the productivity of the sintering machine by giving the pseudo particles obtained by K K the optimum properties.

(Structure of the Invention) The present invention classifies various fine ore brands for sintering raw materials into a plurality of groups according to particle size, blends each fine ore brand group, and then granulates it in one or more drum-shaped granulation lines. When carrying out this process, for fine-grained ore brands, a portion of the powder ore is pre-granulated to produce particles with a particle size of 1.0 to 5.0 in a wet state, and then charged into the granulator. Of the sintered raw materials charged into the granulator, the content in the wet state is 1.0 to 5. On
The weight proportion of particles with a particle size of 1.0 to 5 in the wet state is
．． This is a method for processing a sintering raw material in which the amount is 50 to 70% by weight based on the total weight of particles having a particle size of On and particles having a particle size of 0.5 or less.

Furthermore, an embodiment of the present invention is a method for processing a sintering raw material using a grade of fine ore having fine particle size and relatively high wet strength for pre-granulation.

(Detailed explanation) Pseudo-particles produced in a drum-type granulator have many characteristics regarding their structure.
A particle with a diameter of about 5.0 m forms a core and around it a particle of about 0.5 m.
It is considered to be a structure in which particles of Wa or smaller are attached. The inventors also confirmed this point and found that #
1 obtained similar results.

Furthermore, the present inventors investigated the influence of the space factor of the raw material in the drum and the granulation water content on the strength of the pseudo particles (expressed as the powder percentage after applying a certain impact to the pseudo particles), and is 1.0-5.
The influence of the ratio of particles acting as Ota nuclei to particles smaller than 0.5 im and acting as attached powder was investigated.

An example of the results (influence of the ratio of particles of 1.0 to 5.0 m that act as nuclei and particles of 0.5 m or less that act as attached powder) is shown in Fig. 2.

As is clear from Figure 2, if the space factor and moisture are maintained appropriately, the strength of the pseudoparticles will increase with respect to the particles (1,0
~5. It is approximately determined by the ratio of the particle size (diameter of owx) and the particles (diameter of 0.5 m or less) that act as attached powder, and if there are particles that act as nuclei by 50 weight or more with respect to the total rain particles, It was found that the strength of the pseudoparticles could be made sufficiently high9.

Furthermore, it was found that particles with a particle size of 0.5 to 1.0 m did not act as adhesion powder or core particles.

In other words, the drum-type granulator can sufficiently granulate even if fine powder is blended up to a maximum of 50 weight qII, and it is possible to sufficiently granulate fine powder up to a maximum of 50 weight qII without converting the entire amount of fine ore into semi-pellets by preliminary granulation. It can be seen that the fine ore can be charged directly to the drum-type granulator.

However, in the current situation where a large amount of fine ore is received, even if 50% by weight of fine powder is added, there will still be a surplus of fine ore. A method of converting this excess fine ore into semi-pellized or tormented ore may be considered, but in this case there is a problem in that the amount of preliminary granulation is large.

The present invention was made in view of these problems, and involves pre-granulating a portion of surplus fine ore to produce particles of 1.0 to 5.0 grains that act as nuclei, and removing the remaining particles. This is a method of reducing the amount of preliminary granulation by using excess fine ore as adhering powder that adheres to the cores. For example, compared to a method in which the entire amount of fine ore is pre-granulated, the amount of preliminary granulation can be reduced to a maximum of 1/4, and compared to a method in which excess fine ore is semi-pelletized, it is possible to maximize the amount.

Furthermore, in the present invention, as the fine ore to be pre-granulated into core particles, a brand with relatively high pseudo-particle strength is used in a granulation test of a single brand.

According to this method, it is possible to prevent the pre-granulated core particles from generating powder (due to bundling) before granulation in the drum-type granulator.

However, according to this method, 1. With a small amount of preliminary granulation, it is possible to sufficiently attach fine powder to the pseudo particles and make them strong.As a result, the permeability of the raw material on the sintering machine is improved,
As a result, the productivity of the sintering machine can be improved.

The reason why a fine-grained ore is used as the ore to be pre-granulated is that if a fine ore is pre-granulated, the amount of pre-granulation required to form a coarse powder, that is, a core, will be smaller. Also 1, 0-5. Otm particles and 0.5 y
The reason why the ratio of particles of nr or less is set to 50 to 70% by weight is that if it exceeds 70%, the amount of preliminary granulation increases as in the semi-vellet method.

Moreover, if it is less than 50 inches, the strength of the pseudo particles after granulation decreases. Also, the particle size is 0.5 to 1. The reason why Otax particles are not mentioned is that, as mentioned above, these particles do not act as adhesion powder or core particles.

(Embodiment) Figure 5 shows an embodiment in which the method of the present invention is applied to an actual machine. In this embodiment, fine ore f1 to In of each brand unloaded from the ship 1 is piled up in a rough ore yard 2. Next, these fine ore f1 to In are classified into a plurality of groups according to particle size, and blended for each fine ore brand group. ζ
Here, fine ore f, ~/n-x is buried in the blending yard 31 as coarse powder. Also fine ore ft1-1ef
n as a fine powder and buried in the blending yard 3b.

Next, these are mixed by a bedding method in a preset ratio to form B powder, which is charged into a separate mixing tank 4 together with each raw material such as limestone, coke powder, and return ore. A predetermined amount of each raw material is continuously cut out from each blending tank 4 and blended,
Send to primary mixer 5. On the other hand, a part of the fine powder buried in the pending yard 3b is sent to the preliminary granulator 21 for preliminary granulation to produce particles of 1.0 to 1.0 m that act as nuclei, which are then passed to the primary mixer. Send to 5. Of the fine ore sent to the primary mixer 5, 1.0 to 5. Particles with a particle size of On (including those formed by pre-granulation)
The ratio of particles having a particle size of 0.511N or less is 50 to 70% by weight of particles having a particle size of 1.0 to 5.0N to the total weight. The primary mixer 5 performs water addition and granulation, and the secondary mixer 6 is used as necessary.
further granulate. The thus granulated pseudoparticles are fed into a sintering machine 8 to produce sintered ore in the same manner as in the conventional method shown in FIG.

(Experiment example) Five brands (A
-E) was blended in an amount of 20% by weight, and this was used as the basic blending composition. The ore (C-E) here is generally referred to as fine ore.

In addition, the wet strength indicates the strength of pseudo particles granulated using simple ore adjusted to a predetermined particle size.

Regarding the sintering raw materials with this basic composition, the following (1) to (l
It was granulated by the iD method.

(1) The sintered raw material was directly charged into a drum-type granulator and granulated without pre-granulation.

Gl) A coarse ore group consisting of A and B ores,
The fine ore group consisting of C, D, and E ores is classified by particle size, and all or part of the fine ore group is pre-granulated in a pan-shaped granulator, and this is then granulated in a drum-type granulator together with the remaining raw materials. The mixture was charged in the form of grains and granulated.

4iD D ore with fine particle size and high wet strength,
All or part of D ore is pre-granulated in a Nokun-type granulator, and this is then granulated in a drum-type granulator together with the remaining raw material. The mixture was charged into a granulator and granulated.

Of the methods (11), the method of pre-granulating all of the C, D, and E ores corresponds to an improvement on the semi-pellet method disclosed in Japanese Patent Publication No. 39-13012.

Regarding the raw material after granulation thus obtained, the air permeability when formed into a full layer and the sintering time (minutes) by a pan test were investigated. The results are shown in Table 2.

In addition, the air permeability shown in Table 2 and the weight ratio of core particles to the total weight of core particles and attached powder particles (0,5
Figure 3 shows the relationship between the weight ratio of particles of 0 to 5.0 m to the total weight of powders of 1.0 to 5.0 m or less, and the same weight ratios are shown in Table 2. The relationship with the sintering time shown in FIG. 4 is shown in FIG.

From these results, the following can be seen.

(1) As raw materials to be charged into the drum type granulation system, 0,
If the ratio of the weight of particles of 1.0 to 5.0 m to the total weight of powder and particles of 5 m or less and 1.0 to 5.0 tm is maintained at 0.5 or more, air permeability is sufficiently high and Sintering time can also be very short.

Gl) 0.5 mm or less and U1. O~5.0
Pre-granulation is performed to maintain the ratio of wto powder>yo U particles to the total weight of 0.5 or more, but the smaller the particle size of the ore or ore group to be subjected to pre-granulation, the smaller the amount of pre-granulation will be required. .

For example, when a coarse ore group consisting of ores A and B is subjected to pre-granulation, if 601 of the A and B ore groups, i.e. 24% of the total raw material, is not pre-granulated, 0.5 tm
1, 0 to 5 for the weight of powder or particles below and 1.0 to 5. Owxt particle weight ratio 0.5
It is not possible to secure more than that.

On the other hand, when a fine ore group consisting of C, D, and E ores is subjected to preliminary granulation, C, D.

The above weight ratio can be ensured by simply pre-granulating 20 pieces of E ore group, that is, 12 pieces of the total raw material.

4iD If an ore or ore group with fine grain size and high wet strength is used as the raw material for pre-granulation, the amount of pre-granulation can be even smaller than in item (II) above.

For example, when subjecting C, D, E ore groups (fine ores but not high wet strength) to pre-granulation, as described above (201 of C, D, E ore groups, i.e. 1 of the total raw materials)
2% needs to be pre-granulated. On the other hand, when D ore having a fine particle size and high wet strength is subjected to pre-granulation, only 40 tlb of D ore, that is, 8% of the total raw material, needs to be pre-granulated.

In the method of Special Publication No. 39-18012, 60% of the total raw materials
The method of the present invention requires preliminary granulation of approximately 1
A pre-granulation amount of about 3-degrees is sufficient.

In addition, in the above-mentioned example, preliminary granulation was performed using a pan-type granulator, but 1.0 to 5. As long as it is a granulator that can granulate OR particles, it is particularly limited.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a general method for processing sintered raw materials, and Figure 2 shows the strength of the pseudo particles obtained by granulation using a drum-type granulator. The amount of powder of 0.5 or less in the raw material and 1.0 to 5.
Figure 3 is an explanatory diagram of experimental results showing the ratio of the amount of particles with a diameter of 0 mm.
, 1 for the amount of powder below 5 wK and the total amount of particles from 1.0 to 5.0 wx, θ to 5. Figure 4 is an explanatory diagram of the experimental results showing the relationship between the ratio of the amount of Ont particles and the air permeability when the particles are granulated in a drum-type granulator to form a packed bed. 0, 5 present in the raw material just before entering
The ratio of the amount of particles of 1.0 to 5.0 m to the total amount of powder of mtx or less and the amount of particles of 1.0 to 5.0 m An explanatory diagram of experimental results showing the relationship with sintering time when granulated and sintered in a test sintering pot,
FIG. S is an explanatory diagram showing a method for processing sintering raw materials according to an embodiment of the present invention. 1... Ship, 2... Rough ore yard, 3.3a, 3b.
...Blending yard, 4-...Blending tank, 5...
Primary mixer, 6...Secondary mixer, 7--E,) mother, 8-Sintering machine, 9--Δlet, 1o/single-ignition furnace, 11
...Wind box, 21.-Preliminary sintering machine. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2
t *1.0-0-5i) T1 wood m strip v1 [Figure 3 drum'ffi! L [05mm or more of M'Ff) Outside Australia 1
1◆1.0-5.0ηm a-W Fig. 4

Claims (2)

[Claims] (1) When granulating various powdered ore brands for sintering raw materials into multiple groups according to particle size and blending each powdered ore brand group, one or more drum-type granulation lines are used. For fine powder ore brands, a part of it is pre-granulated to produce particles with a particle size of 1.0 to 5.0 mm in a wet state, and then charged into the granulator. 1.0 to 5.0 mm of the sintered raw material in the wet state
The weight proportion of particles with a particle size of 1.0 to 5 in the wet state is
．． A method for processing a sintering raw material in which the amount is 50 to 70% by weight based on the total weight of particles having a particle size of 0 mm and particles having a particle size of 0.5 mm or less. (2) Processing of the sintered raw material according to claim 1, wherein the powder ore brand that is pre-granulated and then charged into the granulator is a brand that has fine grain size and relatively high wet strength. Method.