JPH1192834A - Production of sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity of sintered ore by using an existing equipment in a mixed granulating process and improving the granulating property to improve the air permeability of sintering raw material. SOLUTION: Individual pseudo granulating indices of the raw materials for sintered ore is previously obtd. and the raw materials for sintered ore are divided into an iron ore group having high pseudo granulating index and an iron ore group having low pseudo granulating index based on the previously obtd. individual indices. After applying a granulating promotion means to the iron ore group having low pseudo granulating index, the mixing and the granulation are executed in each of two iron groups and, thereafter, these granulated materials are mixed to execute sintering, wherein, the pseudo granulating index (mass%) is [(the ratio of the raw material having <0.25 mm size before granulation - the ratio of the raw material having <0.25 mm size) after granulation/(the ratio of the raw material having <0.25 mm size before granulation)]×100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered ore, which is a raw material for iron making, and more particularly, to a method for sintering a raw material having good air permeability by improving the granulation of the raw material. And a method for producing a sintered ore.

[0002]

2. Description of the Related Art In general, the production of sintered ore used as a raw material for iron making is performed by a pre-processing step of the sintering raw material shown in FIG. This pre-treatment step includes a mixing and granulating step including a raw material tank 1 and a drum mixer 2, and a feed hopper 3,
The sintering process includes a sintering process. Solid fuels such as fine iron ore, sintering raw materials, CaO-containing auxiliary materials (quick lime, limestone, etc.), SiO ₂ -containing auxiliary materials (silicaite, serpentine, etc.) and coke powder are stored in a raw material tank. I have. These raw materials are blended in a predetermined amount, charged into a drum mixer, further mixed with an appropriate amount of water, and granulated.
Next, the granulated material is charged to a suitable height on a pallet of a sintering machine (for example, a Dwyroid type sintering machine) by a feed hopper, and the solid fuel in the surface layer is ignited. After ignition, the solid fuel is burned while sucking air downward, and the compounding material is sintered by the heat of combustion.

[0003] The above-mentioned granulated material loaded on a pallet of a sintering machine is required to have air permeability in order for the sintering reaction to proceed uniformly and sufficiently. In order to improve the air permeability, the sintering raw material is coarsened and the sintering raw material is improved in granulation property. That is, the airflow resistance is reduced. For this reason, binders (quick lime, bentonite, cement, cement clinker powder, etc.) are added to increase the amount of the raw material for coarse particles and to promote granulation.

In order to improve the permeability of the sintering raw material,
A method of dividing and granulating the fine powder and coarse powder of the sintering raw material has been proposed (Fig. 4: Materials and processes, edited by The Iron and Steel Institute of Japan)
Vol. 10 (1997) p. 190). This method conventionally comprises a step of selectively granulating and strengthening the fine powder of the sintering raw material (20% by mass of the whole raw material) by forcibly stirring with water while the whole raw material is granulated at once. To add. It has been suggested that the granulation rate can be improved by this split granulation, and the air permeability can be improved.

[0005]

However, with the decrease in the yield of high quality iron ore in recent years, the number of brands of iron ore to be used has increased, and the granulation properties of sintering raw materials have been greatly affected by these brand characteristics. I have. That is, with the decrease in the mixing ratio of the coarse-grained raw material, and the increase in the amount of iron ore of the brand with poor granulation properties and the sintering ore with the same poor granulation property, the granulation properties of the sintering raw materials decrease. Is to occur. For this reason, there is a problem that the permeability of the sintering raw material decreases, and the productivity of the sinter decreases.

[0006] In the above-mentioned divided granulation, there is also a case where the remaining 80% of the coarse powder raw material may have a brand having poor granulation properties. There is. In addition, a new mixer is required to forcibly agitate the fine powder, which complicates the operation and increases the equipment cost.

[0007] Accordingly, the present invention is to improve the granulation of the sintering raw material and improve the permeability of the sintering raw material by using the existing mixing and granulation equipment, thereby producing sinter ore. The purpose is to improve the performance.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively studied the properties of the sintering raw material and the mechanism of pseudo-particle formation in order to improve the granulation property of the sintering raw material. Was done. As a result, the mixing and granulating processes are divided into two systems, and the raw materials are grouped based on the degree of pseudo-particle formation of the sintering raw materials to enhance the granulation of raw materials with poor pseudo-particle formation, thereby obtaining a sintered raw material. The present inventors have found that the granulation property can be improved, and completed the present invention.

According to the first aspect of the present invention, in the present invention, the sinter ore raw materials having a high pseudo-grain index are determined from the individual pseudo-graining indices of the raw materials for the sinter ore. After the stone group and the iron ore group having a low pseudo-graining index are subjected to granulation promoting means, the iron ore group having a low pseudo-graining index is mixed and granulated for each of the two iron ore groups. The sintering is performed by mixing these granulated materials. Here, pseudo-granulation index (% by mass) = (Ratio of raw material less than 0.25 mm before granulation−0.25 mm after granulation)
Less than the ratio of raw materials less than 0.25 mm before granulation) × 100.

[0010] There is a correlation between the air permeability and the quasi-particle index,
By using the pseudo-particle index, the effect on air permeability and the degree of pseudo-particle conversion of the sintering raw material can be determined accurately.
Further, the iron ore group having a high pseudo-graining index and the iron ore group having a low pseudo-graining index are separated, and the ore group having a low pseudo-graining index is subjected to granulation promoting means. By performing mixing and granulation every time, and then mixing these granulated materials, it is possible to strengthen the granulation of iron ores having a low pseudo-particle index, and as a whole the granulation properties of the sintering raw material Can be further improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the granulation promoting means adds a binder only to a group of iron ores having a low pseudo-particle index. It is. By adding a binder only to the iron ore group having a low pseudo-graining index, it is possible to effectively enhance the granulation of the iron ore group having a low pseudo-graining index. Can be further improved.

According to a third aspect of the present invention, in the first aspect of the invention, the granulation accelerating means is configured to adjust the amount of the binder to be added to the iron ore group having a low pseudo-graining index. Iron ore group. By increasing the amount of binder added to the iron ore group with a low pseudo-graining index compared to the iron ore group with a high pseudo-graining index, it is possible to effectively enhance the granulation of the iron ore group with a low pseudo-graining index. In addition, the granulation property of the sintering raw material can be further improved, and the sintering time of the sinter can be reduced, and the productivity of the sintering furnace can be improved.

According to a fourth aspect of the present invention, in the constitution of the first or second or third aspect, the high pseudo-particle index is 40% by mass or more and the low pseudo-particle index is less than 40% by mass. It is characterized by the following. By properly separating the iron ore group having a high pseudo-graining index and the iron ore group having a low pseudo-graining index, the granulation of the sintering raw material can be efficiently improved as a whole.

The method for producing a sintered ore of the present invention will be further described. The granulation property of the sintering raw material is determined based on the degree of pseudo-particle formation due to the combination of the constituent particles of the sintering raw material. The quality of the quasi-particles is affected by the properties of the sintering material such as water absorption capacity, surface shape, and viscosity. Pseudo-particle formation is caused by filling the gaps between the raw material particles with water and being combined by the surface tension of water. In particular, in many cases, fine powder is combined with coarse powder as a nucleus to form pseudo-particles.

[0015] Then, the iron ore R (brand) as a sintering raw material was compared in terms of particle size (particle size after forming into pseudo particles) after raw material cutting and granulation by a drum mixer. This is shown in FIG. Comparing the particle size distribution after the raw material cutting and the granulation, after granulation, the ratio of the particle size less than 0.25 mm is smaller than that at the time of the raw material cutting, and the ratio of the particle size of 0.25 mm or more is increased. I knew I was doing it. Thus, 0.25m
It was found that particles having a particle size of less than m were combined to form pseudo particles.

Therefore, it is possible to judge the quality of pseudo-particle formation by paying attention to the change in the ratio of the particle size of less than 0.25 mm to that of the raw material after granulation.
As a result, the quasiparticle index was defined as follows. Pseudoparticle formation index (% by mass) = (Ratio of raw material less than 0.25 mm before granulation−Ratio of raw material less than 0.25 mm after granulation) / (Ratio of raw material less than 0.25 mm before granulation) ) × 100 ・ ・ 1 set

Next, with respect to the compounding material of the sintering raw material, granulation was performed for each compounding material, the particle size distribution before and after the granulation was measured, and the pseudo-particle conversion index was calculated. This is shown in Table 1. From Table 1, it can be seen that iron ore A, iron ore C, limestone, sinter remineralization and the like have a low pseudo-particle index and are materials to be improved in granulation properties. For these materials with low pseudo-particle index,
It is effective to add a binder (for example, quicklime) to strengthen granulation.

[0018]

[Table 1]

In the conventional method, the total amount of the sintering raw materials is blended, mixed by a drum mixer, and the change of the quasi-granulation index at the time of granulation is examined in detail. It was found that a material that promotes pseudo-particle formation but has a low pseudo-particle formation index does not have a higher pseudo-particle formation index than the material itself has. Therefore, it is effective to group the raw materials based on the degree of quasi-particle formation of the sintering raw materials and to enhance the granulation of the raw material having poor pseudo-particle formation. The material having a low pseudo-granulation index is the other series, and the binder is further added to enhance the granulation, whereby the material having a low pseudo-granulation index can be granulated with a higher pseudo-granulation index. By mixing the granulated material with a material group having a high pseudo-particle-forming index granulated by another system, it is possible to further increase the pseudo-particle-forming index as compared with the conventional method.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a pretreatment process of a sintering raw material of the present embodiment. Table 1 is a table showing the quasi-particle formation index of the sintering raw materials used in the present example, and Table 2 is an example of the mixture of the sintering raw materials in the present example. First, the pretreatment step (see FIG. 1) of the sintering raw material according to the present embodiment is the same as the conventional pretreatment step of the sintering raw material (see FIG. 3). It is a characteristic that The A system mixes and granulates iron ores having a high quasi-granulation index, and the B system mixes and granulates iron ores with a low quasi-granulation index. These granules were mixed and stored in the feed hopper 3. The mixed granulated material was filled on a pallet of the sintering machine 4 and sintered by the ore feeding hopper.

Table 2 shows the sintering raw materials used. Regarding the particle size of the sintering raw material, the iron ore was adjusted to be under 8 mm, and the auxiliary raw material was adjusted to be under 5 mm. The comparative examples are the mixing ratios of the conventionally used sintering raw materials. First, in order to select a brand to be selectively granulated, the dry particle size of each brand and the particle size after granulation were measured, and the pseudo-particle formation index was determined in advance by the method described above. Table 1 shows the results.

Inventive method-1 is a method in which, among the conventionally used sintering raw materials, iron ore A and iron ore C each having a pseudoparticle index of less than 40% are blended with quick lime as a binder. Limestone having a chemical conversion index of less than 40% was blended to obtain a B-based raw material. The A-based raw material is obtained by removing the B-based raw material from the conventionally used sintering raw material. Invention method-2 also
For iron ore A and iron ore C whose pseudo-particle index is less than 40%,
Quick lime was blended, and sinter ore having a pseudoparticle index of less than 40% was blended to obtain a B-based raw material. Similarly, the A-based raw material is obtained by removing the B-based raw material from the conventionally used sintering raw material. Invention method-2-A and invention method-2-B are:
The same raw material blending as in Invention method-2, in which quicklime as a binder is blended into both raw materials. In these test materials, the blending ratio of quicklime in the B-based raw material having a low pseudo-particle formation index is increased to perform a gradient blending of quicklime.

[0023]

[Table 2]

In the mixing and granulating steps, each raw material group was previously blended, and then water was added to make the blended water a moisture of 7% by mass, and the mixture was granulated by a drum mixer. Sampling was performed on the mixed powder at the time when each raw material group was previously blended and on the granulated product, and the particle size distribution was measured. Next, Invention Method-1,
In Invention Method-2, Invention Method-2-A, and Invention Method-2-B, the A-based material and the B-based material are mixed with a conkle mixer, and the mixed material is sampled to determine the air permeability and the particle size distribution. It was measured. The air permeability was measured by an air permeation method. The air permeability at this time is defined by a flow through a unit volume of raw material under a certain pressure gradient, and JPU (Japanese Permeability Unit) is used as the air permeability of the sintering raw material. Air permeability = (F / A) × (H / S) ^0.6 where: F: flow rate (m ³ / min) A: suction area (m ² ) H: filling thickness (m) S: negative pressure (mmaq) The quasi-particle formation index was calculated by using the above-described formula (1) based on the measurement result of the above-mentioned particle size distribution.

As shown in Table 3, the air permeability was 3 in the comparative example.
The value of 0.2 was remarkably improved from 34 to 35 in the method of the present invention. This is due to the enhanced granulation of the iron ore group having a low pseudo-graining index. That is, the pseudo-particle formation index of the comparative example was 82.7% by mass, but 90.8% by mass in Invention Method-1 and 93.3% in Invention Method-2.
% Of the iron ore group (B-based raw material) having a low pseudo-graining index, which is particularly evident from the high pseudo-granulation index.

[0026]

[Table 3]

Next, Invention Method-1, Invention Method-2, Invention Method-
The raw material filling height was 500 mm and the air suction pressure was 1 for the mixed raw material of 2-A and Invention Method-2-B and the raw material of Comparative Example.
A sintering experiment using a sintering pot was performed under the conditions of 000 to 1600 mmaq. Table 4 shows the results. The productivity of the sinter increased with the improvement of the air permeability, and the yield of the method of the present invention increased from 64% of the comparative example to 65 to 69%. And
Invention method in which quicklime as a binder is blended with both raw materials
In A and Invention Method-2-B, the sintering time was shorter than that of Comparative Example, and the production rate was significantly improved.
In B, the production rate was improved by about 26% as compared with the comparative example.

The sintering time was shorter than that of the comparative example.
By blending quicklime of the binder into both raw materials,
It is considered that the pseudo particles of both raw materials were kept by the quicklime of the binder, and the air permeability did not decrease. As described above, the quicklime of the binder is blended into two iron ore groups, and the blending ratio is set such that the iron ore group having a low pseudo-particle index (B-based raw material) and the iron ore group having a high pseudo-particle index (A It has been found that by blending more than the raw material, the permeability of the sintered ore can be improved and the productivity of the sintered ore can be further improved.

[0029]

[Table 4]

In the present invention, the mixing and granulating processes are divided into two systems,
By grouping the raw materials based on the degree of pseudo-granulation of the sintering raw materials to enhance the granulation of raw materials with poor pseudo-granularity, the granulation properties of the sintering raw materials can be improved. The air permeability of the raw material could be improved, and the productivity of the sintering machine could be improved.

Without being limited to the embodiments of the present invention, sinter refining, limestone,
Coke powder and the like can be appropriately divided and mixed into an iron ore group having a high pseudo-particle index and an iron ore group having a low pseudo-particle index. In addition, bentonite, cement, cement clinker powder, and the like can be used as a binder for promoting granulation, in addition to quick lime.

[0032]

As described above, according to the present invention, the sinter ore raw materials having a high quasi-particle index are obtained from the sinter ore raw materials in advance. By dividing the ore group and the iron ore group with a low pseudo-graining index, and performing granulation accelerating means on the iron ore group with a low pseudo-graining index, by mixing and granulating for each of the two iron ore groups, Thus, the granulation of the sintering raw material can be improved, and as a result, the permeability of the sintering raw material can be improved, which has the effect of improving the productivity of the sintering machine. Furthermore, it is possible to cope with the diversification of brands of iron ore due to a decrease in the output of good quality iron ore in recent years, and to enable stable production of a sintering machine.

[Brief description of the drawings]

FIG. 1 is a view showing a pretreatment step of a sintering raw material of the present invention.

FIG. 2 is a view for explaining a pseudo-graining index (GI index), showing a particle size distribution of a sintering raw material.

FIG. 3 is a view showing a conventional pretreatment process of a sintering raw material.

FIG. 4 is a view showing a conventional pretreatment process of a sintering raw material for performing split granulation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material tank 2 Drum mixer 3 Mining hopper 4 Sintering machine 5 Forced mixer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiro Nishiguchi 1 Kanazawa-cho, Kakogawa-shi, Hyogo Kobe Steel, Ltd. Inside the Kakogawa Works

Claims (4)

[Claims] 1. A method for obtaining individual pseudo-particles of a raw material of a sinter ore in advance, from which iron ore group having a high pseudo-particle-forming index and iron ore having a low pseudo-particle-forming index are obtained. After the iron ore group having a low pseudo-particle size index is subjected to granulation promoting means, the two ore groups are mixed and granulated, and then these granulated materials are mixed and sintered. A method for producing a sintered ore, comprising sintering. Here, pseudo-granulation index (% by mass) = (Ratio of raw material less than 0.25 mm before granulation−ratio of raw material less than 0.25 mm after granulation) / (less than 0.25 mm before granulation). (Raw material ratio) × 100. 2. The method for producing a sintered ore according to claim 1, wherein the granulation accelerating means is to add a binder only to a group of iron ores having a low pseudo-particle-forming index. 3. The sintering method according to claim 1, wherein said granulation accelerating means increases the amount of a binder added to the iron ore group having a low pseudo-graining index compared to the iron ore group having a high pseudo-graining index. How to make ore. 4. The high quasi-particle index of 40% by mass or more and the low quasi-particle index of less than 40% by mass.
Or the method for producing a sintered ore according to 3.