JPH05239560A - Manufacture of sintered ore - Google Patents

Abstract

PURPOSE:To improve the productivity of sintered ores without aggravating the yield even if pulverized ore is blended and adding quantity of carbonaceous material is reduced at the time of executing the sintering of the iron ore. CONSTITUTION:In a manufacturing method of the sintered ore blended with the pulverized ore containing >=70wt.% of <=0.125mm particles together with the other sintering main raw material, sintering auxiliary raw material and the carbonaceous material, this pulverized ore is beforehand granulated together with a part of the sintering main and auxiliary raw materials and the carbonaceous material, and separately, the remained sintering raw materials are mixed and granulated, and the above pre- granulated materials and this later granulated materials are directly carried separately to a surge hopper for sintering machine without executing mutually mixing treatment. Then the carbonaceous material quantity Mc1 blended at the time of pre-granulating in the former and the carbonaceous material quantity Mc2 blended at the time of granulating in the latter are adjusted so as to satisfy the inequality Mc1/(MpF+MsF1)< Mc2/MsF2. In the inequality, MpF: the pulverized ore-blending quantity into the pre- granulated material, MsF1: the sintering main and auxiliary raw material-blending quantity into the pre-granulated material, MsF2: the sintering main and auxiliary raw material-blending quantity into the latter granulated material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention improves the productivity of sinter while using fine ore as a raw material for sintering when sintering iron ore to produce sinter. The present invention relates to a method of reducing the amount of carbonaceous material used as a fuel for use.

[0002]

2. Description of the Related Art The proportion of fine iron ore used as a sintering raw material tends to increase, but 70% by weight of particles of 0.125 mm or less
When the fine ore contained above is used as a part of the sintering raw material, it is mixed with other main and auxiliary raw materials for sintering and granulated and supplied to the sintering machine. It is known that the air permeability in the sintering process is impaired and the productivity of sinter is deteriorated.

As a method for improving this problem, Japanese Patent Publication No. 2-
In 37410 and JP-A-61-213328, granulation is performed in advance so that fine ore is attached to the surroundings of return or limonite as a nucleus, and this pre-granulated product is used as a main or secondary sintering additive. We propose a method of mixing and granulating with the raw materials.

Further, Japanese Patent Application Laid-Open No. 63-186832 proposes that a granulated product of fine ore and return ore be charged as a substitute for bedding ore into a sintering machine.

[0005]

[Problems to be Solved by the Invention] The former method in which fine ore is adhered to the surroundings of return ore and limonite to be pre-granulated, and the pre-granulated product is mixed and granulated with other main and auxiliary raw materials for sintering. In the case of mixed granulation of the pre-granulated product and other main and auxiliary raw materials for sintering, part of the pre-granulated product collapsed and became fine powder form again as other main and auxiliary raw materials for sintering. There is a problem of mixing. In other words, this collapsed part behaves in the same way as when the pre-granulation process is not performed, and if this collapse occurs, the productivity of the sintered ore will not be sufficiently improved despite the preliminary granulation. The problem came with it.

Further, this pre-granulated product is more likely to collapse as the amount of the fine ore compounded increases, so that it is difficult to produce a sinter by mixing a large amount of the finely divided ore by this method.

In addition, when the obtained pre-granulated product is mixed and granulated with other raw materials, coke and the like mixed with other raw materials on the surface of the pre-granulated product in the mixed granulation process. The carbonaceous material will adhere, but it is difficult to control the adhered amount to a constant value. In general, granules tend to be deposited at a low level in the lower part of the raw material layer on the sintering machine. Therefore, the lower part of the raw material layer becomes uneven due to fluctuations in the amount of coke adhering to the pre-granulated product. This results in firing, which causes a decrease in the yield of sinter. As a countermeasure, there was a problem that the amount of carbonaceous material added had to be increased.

On the other hand, in the latter method of using a granulated product of finely powdered ore and return ore as a bedding ore, since this granulated product is not mixed and granulated with other main and auxiliary raw materials for sintering, Although the problem of disintegration does not occur, the amount of the granulated product used is limited to bedding ore, and therefore the sintering machine cannot be filled in a large amount. Therefore, this method cannot produce a sinter by mixing a large amount of fine ore.

An object of the present invention is to solve the above problems, improve the productivity of sinter even if a large amount of fine ore is added, and further reduce the amount of carbonaceous material added. Another object is to provide a sintering method that does not reduce the yield.

[0010]

[Means for solving the problem] 70 particles of 0.125 mm or less
In a method for producing a sintered ore in which fine ore contained in an amount of not less than wt% is mixed into a sintering raw material together with other sintering main raw materials, sintering auxiliary raw materials, and carbonaceous materials, the present invention provides Pre-granulation together with a part of raw materials and carbonaceous material, separately mixing and granulating the remaining sintering raw materials, and then performing a process of mixing the former pre-granulated product and the latter mixed granulated product with each other Directly into the surge hopper of the sintering machine, and the former amount of carbonaceous material Mc ₁ to be blended during pre-granulation and the latter amount of carbonaceous material to be compounded during mixed granulation Mc ₂ are expressed by the following formula ( It is characterized by adjusting so as to satisfy 1). Mc ₁ / (Mp _F + Ms _F1 ) <Mc ₂ / Ms _F2 (1) However, in the formula (1), Mp _F is the amount of fine ore compounded in the pre-granulated product Ms _F1 is the firing of the pre-granulated product Coupling amount of main and auxiliary materials Ms _F2 is the mixing amount of sintering main and auxiliary raw materials in the case of mixed granulation, and the unit is weight.

[0011]

In the present invention, finely divided ore means iron ore containing particles of 0.125 mm or less in an amount of 70% by weight or more. Sintering main raw material refers to iron ore other than the fine ore, such as limonite, hematite, magnetite, and return ore at the time of sintering, which do not contain 70% by weight or more of particles of 0.125 mm or less, that is, fine powder. It has a larger particle size and particle size distribution than ore (coarse particles). Sintering auxiliary materials refer to slag components, binders, etc.
Specifically, it is serpentine, dolomite, limestone, quicklime, etc., which are often coarse particles, but fine particles can also be used. The carbonaceous material usually refers to powder coke, but coal, for example, anthracite powder, or a char obtained by pyrolyzing coal can also be used.

FIG. 1 illustrates a preferred embodiment of the method of the present invention. The method of the present invention will be described with reference to FIG.

First, the pre-granulation of fine ore is performed by the granulator 1. The granulator 1 is preferably a pelletizer capable of obtaining granules having a narrow particle size distribution,
It can also be performed with a mixer. The fine ore 2, the sintering main and auxiliary materials 3 and the powder coke 5 stored in the hopper are cut into predetermined amounts, respectively, charged into the granulator 1, and an appropriate amount of water 6 is added to perform the granulation process. The pre-granulated product 7 is obtained. At that time, the binder 4 (for example, quicklime or slaked lime powder) can also be mixed in an appropriate amount. As described above, coal powder or char can be used instead of powder coke.

In FIG. 1, the main sintering auxiliary material 3 is illustrated as being stored in one hopper, but it may be stored in separate hoppers. Sintering main raw material 3 is sinter feed of return ore, limonite, hematite, magnetite, or coarse-grained limestone, dolomite, serpentine, etc. The main raw material used for pre-granulation is at least 1 of these. Any type may be used, and not all types need be used.

On the other hand, the remaining sintering raw materials are mixed and granulated by the mixer 8 in another system. That is, the main auxiliary raw material 9 for sintering stored in the hopper is cut out together with the powdered coke 5 in a predetermined amount and mixed and granulated by the mixer 8 to obtain a mixed granulated product 10.

In this way, the pre-granulated product 7 is obtained from the granulator 1 and the mixed granulated product 10 is obtained from the mixer 8 in different systems. In the present invention, the charcoal is used even in the former pre-granulation. Mix the material (powder coke 5) and distribute the distribution (1)
Adjust as in the formula. Mc ₁ / (Mp _F + Ms _F1 ) <Mc ₂ / Ms _F2 ... (1)

In the equation (1), Mc ₁ is the amount of carbonaceous material blended at the time of pre-granulation, Mp _F is the amount of finely-divided ore compounded at the pre-granulation, Ms
_{Since F1} is the sintering main and auxiliary raw material blending amount of the pre-granulated product, the left side represents the weight ratio of the carbonaceous material in the pre-granulated product 7, M
Since c ₂ is the amount of carbonaceous material blended during mixed granulation, and Ms _F2 is the amount of sintering main and auxiliary raw material blended during mixed granulation, the right side represents the weight ratio of the carbonaceous material of mixed granulated substance 10. .. That is, in the present invention, the total amount of carbonaceous material blended in all the sintering raw materials is distributed by adjusting the addition ratio of the former to a value lower than that of the latter during pre-granulation and mixed granulation.

Pre-granulated material 7 containing carbonaceous material
The mixed granulated material 10 is directly loaded into the sintering machine 11 without being mixed or granulated by the mixer 8 or the secondary mixer. That is, both are directly loaded into the raw material loading surge hopper 12 of the sintering machine 11. Actually, the pre-granulated material 7 and the mixed granulated material 10 are continuously put into the surge hopper 12 in an appropriate amount on the belt conveyor 13 which carries the raw materials into the surge hopper 12, so that they are merged into the surge hopper 12. Is brought in.

Therefore, in the surge hopper 12,
The pre-granulated product 7 will be mixed with the mixed granulated product 10 while maintaining the granulated form obtained by the granulator 1 as it is,
The table (pallet) of the sintering machine 11 in this mixed state
Loaded on top. Then, the surface is ignited by the igniter 14, and the sintering proceeds by downward ventilation.

According to the method of the present invention, since the pre-granulated material charged into the sintering machine maintains the particle morphology during the pre-granulation as it is, the air permeability at the time of sintering becomes good. Therefore, the productivity of the sintered ore can be improved. The details will be shown in an example described later, but from the surge hopper 12 to the sintering machine 11
The granulated product was sampled from the flow of the raw material charged into the reactor, and its harmonic mean particle size was measured. As a result, a sufficient value was retained, and the particle morphology when granulated by the granulator 1 was determined. It was confirmed that it was maintained as it was (for example, FIG. 2 described later). It was also confirmed that the higher the proportion of fine ore in the total raw material, the higher the harmonic mean particle size and the better the air permeability. Here, the harmonic mean particle diameter (dp) is dp = 100 / Σ from the representative diameter (x _i ) in a certain particle size range and its ratio (d _i ).
It is calculated by (x _i / d _i ).

Further, according to the method of the present invention, the carbon concentration distribution in the vertical direction in the raw material layer loaded in the sintering machine tends to be uniform in the entire layer thickness (for example, FIG. 3 described later).
As a result, according to the method of the present invention, it is possible to carry out uniform firing, a sound sintered product can be produced with a high yield, and the firing rate can be increased, so that the productivity is improved together with the improvement of the harmonic mean particle size. It provides the action of being able to.

[0022]

[Examples] Under the compounding ratios shown in Table 1, a pelletizer was used to prepare powder coke compounded pre-granulated products (Examples 1 to 6). The fine ore used is hematite containing 90% by weight of particles of 0.125 mm or less. The water content supplied to the pelletizer was adjusted to a sufficient amount necessary for granulation in each case. On the other hand, the remaining main sintering and auxiliary materials were mixed and granulated with a coke powder in a mixing ratio shown in Table 1 by a mixer. At that time, they were mixed and granulated in two stages, a primary mixer and a secondary mixer. In Table 1, the total of the blends of the pre-granulated product and the blended granulated product is the total sintering raw material (100%).

The pre-granulated product and the mixed granulated product of each example were directly charged into a surge hopper of a sintering machine as shown in FIG. 1 and sintered by the same sintering machine. At that time, sampling was performed from the raw material flow charged into the sintering machine from the surge hopper, and the harmonic mean particle size of the pre-granulated product therein was determined. In addition, in each example, the productivity of sinter (the daily production of sinter per unit sintered area) was determined. These results are also shown in Table 1.

For comparison, an example in which the same fine ore is not granulated before being compounded at the time of mixing and granulating in a mixer (Comparative Example 1) and an example in which a pre-granulating substance is added at the time of mixing and granulating in a mixer ( The composition of Comparative Example 2) is also shown in Table 1. These were also sintered under the same conditions. The harmonic mean particle size and productivity at that time are also shown in Table 1.

[0025]

[Table 1]

As can be seen from the results in Table 1, in Examples 1 to 6 according to the method of the present invention, compared with Comparative Examples 1 and 2, the harmonic mean particle size was large and the productivity of sinter was improved. I understand that Further, comparing Example 2 and Comparative Example 2, for example, the total blending ratio of powder coke in the former is 0.5%.
Although it is decreasing, the yield of sinter can be improved and productivity is improved. The reducible properties (RDI and RI) of the sinter also showed better values than those of the comparative example.

A curve A in FIG. 2 is a plot of the relationship between the blending ratio of the fine ores blended in Examples 1 to 6 and the harmonic mean particle size. From this, it is understood that the harmonic mean particle size is improved by adding a large amount of fine ore. As a result, the productivity is improved when a large amount of fine ore is used.

A curve B in FIG. 2 shows the relationship between the blending ratio of the fine ore and the harmonic mean particle diameter when the fine ore is blended at the time of mixing and granulating in the mixer according to the comparative example 1.
4 shows the relationship between the blending ratio of fine ore and the harmonic mean particle diameter when the pre-granulated product was blended at the time of mixed granulation with a mixer, following Comparative Example 2.

As is clear from the results of FIG. 2, in the curves B and C of the comparative example, the harmonic mean particle size becomes smaller as the blending ratio of the fine ore becomes higher, while in the curve A of the example of the present invention, the fine powder becomes finer. The higher the blending ratio of ore, the larger the harmonic mean particle size. And, the value of the harmonic mean particle diameter is large in the present invention example. Therefore, by applying the method of the present invention, it is possible to use a large amount of fine ore and improve the productivity regardless of the blending ratio of the fine ore.

In FIG. 3, the raw materials charged in the sintering machine were sampled in the height direction in the case of Example 2 and the case of Comparative Example 2, and the C concentration in each raw material was chemically analyzed. The measurement result of C concentration distribution in the investigated layer is shown.

As can be seen from the results shown in FIG. 3, in the case of the comparative example, there was a tendency that the C concentration increased toward the lower layer and the deviation of the concentration also increased. This results in non-uniform firing of the lower layer, which leads to deterioration of the reducible properties due to yield and overmelting. On the other hand, in the case of the method of the present invention, the deviation of the C concentration in the sintering raw material layer becomes small. As a result, uniform firing is possible and the yield is improved. In addition, the low C concentration in the lower layer also prevents deterioration of the reducible property due to overmelting, and in addition, it is possible to keep the total amount of carbonaceous material added low. The speed is increased, and the productivity of the sintered ore can be improved by the combined action with the above-mentioned effect of improving the air permeability.

[0032]

As described above, according to the present invention, the productivity of sinter can be improved even if the amount of fine ore used is increased. Even if the amount of carbonaceous material used as the sintering fuel is reduced, it is possible to produce sinter having a good reducing property with high yield and high productivity.

[Brief description of drawings]

FIG. 1 is a processing system diagram for explaining a method of the present invention.

FIG. 2 is a diagram showing the relationship between the blending ratio of the finely divided ores obtained in the examples of the present text and the harmonic mean particle size in comparison with the comparative examples.

FIG. 3 is a diagram showing a vertical carbon concentration distribution in a raw material layer in a sintering machine according to an example of the present text, in comparison with a comparative example.

[Explanation of symbols]

 1 Granulator 2 Fine ore 7 Pre-granulated material 8 Mixer 10 Mixed granulated material 11 Sintering machine 12 Surge hopper 13 Belt conveyor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Nishimoto 11-1 Showa-cho, Kure-shi, Hiroshima Inside Steel Research Laboratory, Nisshin Steel Co., Ltd. (72) Inventor Nobuichi Aritomi 11-1 Showa-cho, Kure-shi, Hiroshima Nisshin Steel Co., Ltd.

Claims (3)

[Claims] 1. A method for producing a sintered ore, wherein fine ore containing particles of 0.125 mm or less in an amount of 70% by weight or more is compounded in a sintering raw material together with other sintering main raw materials, sintering auxiliary raw materials and carbonaceous materials, The fine ore is pre-granulated together with a part of the main sintering auxiliary materials and carbonaceous material, and the remaining sintering raw materials are separately mixed and granulated,
The former pre-granulated product and the latter mixed-granulated product are directly carried into the surge hopper of the sintering machine respectively without undergoing a process of mixing with each other, and the charcoal compounded during the former pre-granulation is carried out. Adjusting the amount of material Mc ₁ and the amount of carbon material Mc ₂ to be compounded in the latter of the mixed granulation so as to satisfy the following formula (1),
A method for producing a sintered ore, characterized by: Mc ₁ / (Mp _F + Ms _F1 ) <Mc ₂ / Ms _F2 (1) where Mp _F is the amount of fine ore in the pre-granulated product, and Ms _F1 is The sintering main and auxiliary raw material blending amount of the pre-granulated product, Ms _F2 is the sintering main and sub raw material blending amount of the mixed granulated product, and the unit of the amount is weight. 2. The method for producing a sintered ore according to claim 1, wherein a binder is blended with the pre-granulated product. 3. The method for producing a sintered ore according to claim 1, wherein the pre-granulated product and the mixed granulated product are continuously charged on a belt conveyor leading to a surge hopper.