KR102391484B1 - Method for manufacturing granulated sintering raw material and method for manufacturing sintered ore - Google Patents

Abstract

Even when a large amount of finely divided iron ore having a size of -20 μm is blended, granulation property can be improved, and a method for manufacturing a raw material for granulation sinter that is effective in improving the productivity of sintered ore, and sintered ore using this raw material The purpose of the present invention is to propose a method for manufacturing to prepare a raw material for granulation sinter, and the obtained granulated raw material for sintering is used to manufacture sintered ore.

Description

Manufacturing method of granulated raw material for sinter and manufacturing method of sintered ore

The present invention relates to a method for manufacturing a granulated raw material for sinter and a method for manufacturing sintered ore using the same.

The sintered ore used in the blast furnace is a plurality of powder iron ore (for example, "sinter feed" with a size of less than 10 mm (-10 mm)), limestone, silica stone, and serpentine Supplementary raw material powder such as (蛇紋岩), miscellaneous raw material powder such as dust, scale, and semi-gloss, and powdered coke Moisture is added to the raw material for sintering in which solid fuel is blended in an appropriate amount, and then mixed-granulated, and the granulated raw material obtained in this way is charged into a Dwight Lloyd-type sintering machine and calcined. manufactured by Here, since the raw material for sintering usually contains water, when granulated, they aggregate to form pseudo-particles. This pseudo-granulated granulated raw material for sintered ore production, when charged on the pallet of the sintering machine, helps to ensure good ventilation of the sintering material loading layer, and has an effective existence for smoothly proceeding the sintering reaction. do.

It is considered that the granular sintered raw material obtained into quasi-granulated particles has better air permeability as it is of a granular shape, particularly a larger shape, and various methods for improving the granulation property have been studied. For example, as a method of improving the granularity of powdered iron ore, a patent on a method (pre-treatment method of raw materials for sinter) of adjusting the amount of fine powder adhering thereto with respect to the granulation that becomes core particles There is a proposal similar to literature 1-5.

However, with respect to the manufacturing technology of the granulated sintering raw material disclosed in these documents, in addition to the problem of high cost, it is related to the appropriate value of the ore grain size when fine-grained iron ore is mixed in the granulated sintered raw material. There is no review.

In addition, there is also a proposal of a technique for grinding high crystalline water-containing ore, mixing it with all other raw materials, and granulating it to obtain a granulated sintering raw material. (Patent Documents 6 and 7)

However, the use of highly crystalline water-containing ores is a situation in which the use of the ore is not preferable from the viewpoint of the amount of heat or the packed layer.

In addition, there is also a proposal of a technique (patent document 8) in which high porosity iron ore is pulverized and mixed with all other raw materials for granulation. However, it is known that high porosity iron ore has the characteristics that the T.Fe is low and the number of crystals is high, and even if it is pulverized, it adversely affects the operation of the sintering machine in terms of components.

In addition, as another method, a pre-treatment method in which the content of SiO ₂ is 3 to 6 mass% and the particles larger than 63 μm are 90 mass% or more with respect to the total mass of the fine iron ore by pulverizing and using the pulverized iron ore (patent document) 9) is also suggested. However, regarding this technique, proper mixing at the time of using fine grains has not been studied, and the method of using fine grain raw materials for sintering is unclear.

Patent Document 1: Japanese Patent Laid-Open No. 2005-350770 Patent Document 2: Japanese Patent Laid-Open No. 2007-77512 Patent Document 3: Japanese Patent Laid-Open No. 2008-240159 Patent Document 4: Japanese Patent Laid-Open No. 2010-242226 Patent Document 5: Japanese Patent Application Laid-Open No. 2013-32568 Patent Document 6: Japanese Patent Laid-Open No. 2014-196548 Patent Document 7: Japanese Patent Laid-Open No. 2008-261016 Patent Document 8: Japanese Patent Laid-Open No. 2007-138244 Patent Document 9: Japanese Patent Laid-Open No. 2016-17211

The present invention overcomes the above-mentioned problems of the prior art, and in particular, even when a large amount of finely divided iron ore having a relatively size of -20 μm is blended, the nuclear branch index to be described later is appropriately managed. By doing so, it is possible to improve granulation properties, and to propose a method for manufacturing a raw material for granulation sinter that is more effective in improving the productivity of sintered ore, and a method for manufacturing sintered ore using this raw material.

The present invention provides a raw material for granulation sinter using a raw material for sintering containing iron ore in powder form for the above-described problem to be solved, and furthermore, using the raw material for granulated sinter to produce sintered ore to suggest a way. That is, with regard to the production of the raw material for granulation sinter first, paying attention to the nuclear branch index to be described later, powdered iron ore having this nuclear branch index of 2.0 or more is mixed and used in the raw material for sintering, and the production of sintered ore according to the present invention In the above, it is characterized in that sintering is performed using the raw material for granulation sinter obtained as described above.

That is, the present invention is, first, when granular sintering raw material containing granular iron ore is granulated into granular sintered raw material, as the granular iron ore, the nuclear branching index defined below;

Nuclear branching index (-) = {(Particle ratio of +1 mm) + (Particle ratio of -20 μm)}/(Particle ratio of -500 μm)

We propose a method for producing a raw material for granulation sinter, characterized in that using those having a value of 2.0 or higher.

In addition, the present invention, secondly, in a method for producing sintered ore by granulating a sintering blending raw material containing granular iron ore, and sintering the obtained granulated sintering raw material in a sintering machine, as the granulated sintering raw material, nuclear branch index as defined in;

Nuclear branching index (-) = {(Particle ratio of +1 mm) + (Particle ratio of -20 μm)}/(Particle ratio of -500 μm)

The manufacturing method of the sintered ore characterized by using the thing which shows this 2.0 or more is proposed.

Moreover, in the present invention also, the following configuration;

(1) The granulated raw material for sintering is one that is granulated using quicklime as a binder,

(2) When the raw material for granulation sinter is produced using the raw material for sintering and quicklime, the quicklime is added externally in the latter half of granulation;

(3) the granular iron ore in the raw material for sintering, at least a portion of which contains 30 mass% or more of particles having a size of -20 μm;

This is a more preferable embodiment.

According to the present invention, the nuclear branching index representing the blending ratio of granular iron ore of +1 mm, -20 μm, and -500 μm is within a suitable range of 2.0 or more, and quicklime is added externally as a binder. By adopting a method, etc., higher granulation properties can be obtained even under a large amount of finely divided iron ore, and ultimately, it can contribute to improving the productivity of sintered ore, thereby establishing a preferable granulated sintered raw material and manufacturing technology for sintered ore can be suggested.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the relationship between the particle size and air volume of the additive iron ore from which the fine powder ratio differs.
[Fig. 2] It is a diagram showing the relationship between the ratio of -63 μm particles and the maximum adhesive force.
[Fig. 3] A diagram showing the relationship between the ratio of -20 μm particles and the maximum adhesion.
Fig. 4 is a diagram showing the relationship between the ratio of -500 μm and the diameter of the granulated particles.
5 is a diagram showing the relationship between the ratio of -20 μm and the sintering production rate.
6 is a diagram showing the relationship between the nuclear branch index and the sinter production rate.

The inventors first investigated the influence of the particle size of the raw material (iron ore) on the granulation property in granulating the "sintering blending raw material" and manufacturing the "granulated sintering raw material". That is, this investigation is a granulation test and air permeation test performed by substituting the iron ore selected for each particle size with the formulation of the base. As raw materials for the experiment, raw materials (iron ore A to D) shown in Table 1 below were used (CW = water of crystallization). The iron ore B is a thing in which the iron ore A was grind|pulverized and sorted into -1 mm (less than 1 mm), and it is for adding a certain amount in order to control air permeability. In this test, in particular, iron ore D, which is a coordinating ore, was crushed, and iron ore selected through a sieve of (63-125/125-250/250-500/500-1000) μm was added. And as shown in Table 2 below, in order to investigate the influence of the particle size of the conditioning ore, the said test was done also about the thing which did not contain the iron ore D as a base formulation (formulation 6).

In each of the above tests, each raw material for sintering was mixed with a concrete mixer for 3 minutes, then water was added to perform granulation, and the obtained granulated particles were placed in a 150 mmφ, 380 mmH cylindrical container. , the air volume showing air permeability was measured under the conditions of a negative pressure of 700 mmaq. In addition, in this test, the moisture of the granulated material is changed in the range of 6 to 10 mass%, and it is assumed that the moisture at the time of the best ventilation for each formulation is used, and formulations 1 to 5 are all added particle sizes. 8 mass% was optimal, and in formulation 6, 9 mass% was optimal. Moreover, although the thing of the formulation 6 increased the appropriate granulation water|moisture content, the reason was because the iron ore C with much crystal water was used a lot. Iron ore with a large number of crystals generally has many pores, and moisture penetrates into the iron ore during granulation, requiring more moisture than dense iron ore. In addition, regarding formulations 1 to 5, although the particle size was different, since the iron ore species did not change, the appropriate moisture did not change.

As a result, in the air permeability test, as shown in FIG. 1, the thing of -63 micrometer (less than 63 micrometers) resulted in air permeability better than the base formulation 6. However, it turned out that the thing of the particle size of +63 micrometer causes deterioration of air permeability. Therefore, it was found that blending the particles of +63 mu m had a bad influence on the fall of granulation properties and, by extension, on air permeability. In this respect, it can be considered that increasing the blending of particles of -63 μm leads to improvement of air permeability. Summarizing the above, it can be said that when mixing -1 mm (-1000 μm) particles, increasing the mixing of -63 μm particles, that is, finely divided iron ore is effective for improving air permeability.

However, the granulation phenomenon of iron ore and the like is a phenomenon in which fine iron ore is sequentially attached to the surface of the granular iron ore that becomes the nucleus particle. Therefore, in the granulation, the adhesion of the pulverized iron ore to the surface of the nuclear particle becomes important. Therefore, a shear test for measuring the adhesive force affecting the assembly was performed. In this test, -500 μm powder iron ore selected through a 500 μm sieve is charged into a container (43 mmφ) fitted with a fixed mold and a movable mold, and is compressed to 200 kgf by an upper piston, and then , by measuring the shear stress corresponding to the vertical stress by pulling the movable part in the horizontal direction with a full gauge while decreasing the vertical stress. Here, as the adhesive force, shear stress when the normal stress was set to 0 kgf was used. The test was performed about iron ore A and iron ore C-F in Table 3. The particle size of the sample was evaluated for each iron ore, a sample selected to be -500 µm and a sample set to a size of 63 to 125 µm, and also the sample obtained by grinding iron ore D was evaluated.

As a result, as shown in Table 3, Fig. 2, and Fig. 3 below, as the ratio (mass%) of -63 μm or -20 μm increased, it was found that the adhesion force (kPa) of iron ore increased. Here, the ratios of -63 μm and -20 μm are results obtained by measuring the particle size of iron ore (-500 μm) selected, adjusted to 63 to 125 μm, and crushed iron ore D by laser scattering/dispersion measurement. . In particular, regarding the ratio and adhesion of -63 μm and -20 μm, multiple regression analysis was performed using a quadratic function, and the correlation coefficient was 0.93 in the case of -63 μm. At -20 μm, the correlation coefficient was 0.93. It was 0.98, and it was found that the proportion of particles of -20 µm had a larger contribution to the adhesion force.

Moreover, from the test result matching the particle diameter of iron ore, even if the item of iron ore was changed, it also became clear that adhesive force does not increase unless there is -20 micrometers. In this respect, in the conventional invention (Japanese Unexamined Patent Application Publication No. 2008-261016), when pulverized, goethite or kaolinite is selectively pulverized, so that the contribution to adhesion is high, but in the present invention , found that, by making the grain size of the iron ore fine, the adhesion strength was significantly increased even in iron ore D having a goetite and kaolinite content of 0.1 mass% or less (measured by XRD).

Next, the granulation test and the sintering test which changed the ratio of -20 micrometers were implemented. In this test, although it is a fine-grained iron ore, it tested about the iron ore G and the iron ore H which performed the grinding|pulverization process with few -20 micrometers. The conditions and results of the test are as shown in Table 4 below. In addition, regarding the formulation of iron ore A, in Case 1 and Case 2, the nucleus and fraction are changed, and the basicity is set to 2.1, and SiO ₂ is also made constant. The test was done. In implementation of the test, the sample was granulated for 6 minutes with a drum mixer, and baking was performed using the pot tester. Regarding the sinter cake after baking, when it is dropped once from a height of 2 m, a particle having a particle size of +10 mm is taken as a product, and the weight is (sinter cake weight - top light) ) weight) was taken as retention (yield). In addition, the sintering production rate (t/(m 2 ·h)) is a value obtained by dividing the product weight by the firing time and the cross-sectional area of the test pot.

As shown in Fig. 4, in Case 1 with a large number of -20 µm, the granulated particle diameter increases even if the fine powder (-500 µm), which is normally considered difficult to granulate, increases, while in Case 2, where -20 µm is small. , it was found that as the fine powder increased, the granulated particle diameter decreased. However, in case 1 in which the granulated particle diameter was increased, it became clear that the production rate in sintering decreased as shown in Fig. 5 despite the increase in -20 mu m to increase the granulated particle size.

In general, the granular sintered raw material (pseudo-particles) obtained by granulating iron ore (raw material) composed of nuclear particles and fine powder has a structure in which fine powder or particles slightly smaller than the nuclear particles are attached (coated) around the core particles. am. In the wet zone of the sintering machine, in such a granulated raw material for sinter (pseudo-particles), since the surface coating layer part absorbs moisture, the strength decreases and it becomes easy to differentiate, and this As a result, the voids in the filling layer (sintered material charging layer) may be reduced, thereby inhibiting ventilation. In order to solve the problem, it is important to maintain the strength of the raw material for granulation sinter in the wet zone.

As a method of maintaining the strength of the granulated sintered raw material in the wet zone, the aggregate that does not collapse even in the wet zone (+1 mm nuclear particles) does not decrease with respect to the fine amount. , or rather, it is effective to increase it, and it becomes possible to aim at the improvement of air permeability by this. That is, particles of +1 mm (1 mm or more) become nuclear particles during granulation to promote the granulation action, and since the particles themselves are large, they serve to improve air permeability during sintering. In addition, in the sintering raw material loading layer, the ventilation resistance increases in the wet zone where the strength of granulated particles decreases due to increased moisture and in the melting zone where the granulated sintering raw material melts, but aggregate particles of +1 mm By being present, it becomes the action of suppressing the fall of air permeability.

On the other hand, particles of -500 µm tend to form a slurry in the wet zone when they become part of the granulated particles, and in the molten zone, because they are fine, are easily melted, which increases the ventilation resistance.

In this regard, the inventors found that the sum of the ratio of particles of +1 mm that becomes nuclei at the time of granulation and aggregates at the time of sintering and the ratio of particles of -20 μm that contributes to granulation, which adversely affects air permeability It was found that it can be summarized by the following nuclear branching index (-), which is a value divided by the particle ratio of -500 μm. That is, the nuclear branch index can be expressed by Equation (1) below.

[Equation 1]

Nuclear branching index (-) = {(Particle ratio of +1 mm) + (Particle ratio of -20 μm)}/(Particle ratio of -500 μm)

6 shows the relationship between the nuclear branching index and the sintering production rate. As is clear from this figure, and as is also clear from the examples described later, the sum of the ratios of particles of +1 mm and -20 μm to particles of -500 μm that exerts a bad influence is 1.8 or more, preferably It has been found that, by setting it to 1.9 or more, particularly 2.0 or more, it is possible to produce a coarse-grained raw material for sintering for maintaining desirable sinterability even when the particle ratio of -500 µm is high.

In addition, in the present invention, in order to suppress the influence on the wet zone of the sintering raw material charging layer on the sintering machine, quicklime is externally added as a binder in the second half of the granulation process by the drum mixer. adopt a method Also, during the granulation process, external addition of quicklime as a binder has two effects. One of them is the action of absorbing moisture in the wet zone by leaving water and unreacted CaO, and is effective in suppressing the formation of slurries of pseudo-particles. And the other is that Ca(OH) ₂ reacted with water is on the outer side of the pseudo-particles, so it reacts with CO ₂ in the exhaust gas to produce fine CaCO ₃ , and for that reason A strong layer is formed on the surface of the pseudo-particles, making it possible to form a filling layer (sintered material charging layer) that is not easily damaged even in a wet zone.

Example

[Example 1]

In this Example, the following sample (basicity: _2.0 , SiO2:5.0 mass%) was granulated with a drum mixer for 6 minutes, and it sintered using the pot tester. When the sinter cake after sintering was dropped once from a height of 2 m, the value obtained by dividing the weight by (sinter cake weight - top light weight) was taken as a property with a particle diameter of +10 mm. The sintering production rate (t/(m 2 ·h)) was defined as the value obtained by dividing the product weight by the firing time and the cross-sectional area of the test pot.

As a result, as shown in Table 5 and Fig. 6, with respect to particles of -500 μm that exert a bad influence, the sum of the proportions of particles of +1 mm and -20 μm is 2.0 to 2.3 times, Case 1-1, Case 3 -1, Case 3-3 maintains a stable high sintering production rate compared to other Cases 1-2, 1-3, 3-2, 3-4, even if pulverized iron ore with a high -500 μm particle ratio is contained. It has been confirmed that

[Example 2]

In this example, the result of examination with respect to the presence or absence of addition of quicklime and the timing of addition will be described. The nuclear branching index as shown in Table 6 below was 2.3, 2.2, and 2.2, respectively, and the effect on the production rate was investigated for examples without quicklime, with quicklime (internal), and with quicklime (external). . Other conditions are as follows.

In addition, in this Example, a sample (basicity: 2.1, SiO ₂ : 4.7 mass%) was granulated with a drum mixer for 5 minutes, fired using a pot tester, and the sinter cake after sintering was once from a height of 2 m. When dropped, a particle having a particle diameter of +10 mm is taken as an element, and the value obtained by dividing the weight by (sinter cake weight - top light weight) is reserved, and the sintering production rate (t/(m2·h)) is the weight of the element was taken as a value obtained by dividing the firing time and the cross-sectional area of the test port.

When the result was investigated about the influence by the presence or absence of quicklime addition on the sintering production rate, the direction which added quicklime showed the better result.

This is thought to be because, due to the binder effect by quicklime, the strength in the cold state of the pseudo-particles increased, and the packed layer in the wet zone was further supported by CO ₂ at the time of sintering. do.

In addition, in this test, the effect of covering quicklime was also verified. That is, the following sample (basicity and SiO2: constant) was granulated for ₅ minutes with a drum mixer, and it sintered using the pot tester. When the quicklime was externally covered, quicklime was added at 1/10 of the granulation time of the drum mixer, and then calcined. When the sinter cake after sintering is dropped once from a height of 2 m, a particle diameter of +10 mm is taken as an attribute, and the weight divided by (sinter cake weight - top light weight) is reserved, and the sintering production rate (t/ (m2·h)) was defined as the value obtained by dividing the weight of the product by the firing time and the cross-sectional area of the test pot.

As a result, the production rate of quicklime was improved by exteriorizing the quicklime compared to the case of incorporating it. That is, it was found that, when fine powder was added, the production rate was further improved by externalizing quicklime. In addition, in the case of adding quicklime, it was confirmed that the production rate was larger than that of [Example 1] due to the effect of adding quicklime.

Claims (6)

When a sintering blending raw material containing powdered or granular iron ore is granulated to obtain a granulated sintered raw material, the sintering blended raw material has a particle ratio of -500㎛ (less than 500㎛) exceeding 30 mass%; , +1 mm (1 mm or more) particle ratio is 58 mass% or less, and a nuclear branching index defined below (核粉指數) is a method of manufacturing a raw material for granulation, characterized in that it represents 2.0 or more.
- under -
Nuclear branching index = {(Ratio of particles of +1 mm (1 mm or more)) + (Ratio of particles of -20 μm (less than 20 μm))}/(Ratio of particles of -500 μm (less than 500 μm)) The method according to claim 1,
The granulated sintered raw material is a method of manufacturing a granulated sintered raw material, characterized in that it is granulated using quicklime as a binder. The method according to claim 1 or 2,
When the raw material for granulation sinter is manufactured using the raw material for sintering and quicklime, the quicklime is externally added in the latter half of granulation. The method according to claim 1 or 2,
The granular iron ore in the raw material for sintering, at least a part of it, a method for producing a granulated sinter raw material, characterized in that it contains 30 mass% or more of particles having a size of -20 µm (less than 20 µm). 4. The method according to claim 3,
The granular iron ore in the raw material for sintering, at least a part of it, a method for producing a granulated sinter raw material, characterized in that it contains 30 mass% or more of particles having a size of -20 µm (less than 20 µm). A method for producing sintered ore by granulating a raw material for sintering containing granular iron ore, and calcining the obtained granulated raw material for sinter in a sintering machine,
The sintering blending raw material has a particle ratio of -500 μm (less than 500 μm) greater than 30 mass%, a particle ratio of +1 mm (1 mm or more) is 58 mass% or less, and a nuclear branching index defined below is 2.0 or more. The manufacturing method of sintered ore characterized in that it shows.
- under -
Nuclear branching index = {(Ratio of particles of +1 mm (1 mm or more)) + (Ratio of particles of -20 μm (less than 20 μm))}/(Ratio of particles of -500 μm (less than 500 μm))

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