JP6978734B2 - Manufacturing method of granulated sinter raw material and manufacturing method of sinter - Google Patents

Description

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

The sinter used in the blast furnace is called "sinter feed", which is the size of multiple brands of sinter ore (eg, "less than 10 mm" -indicated as "-10 mm" in the description below. Add water to the sintered compounding raw material, which is a mixture of auxiliary raw material powder such as limestone, blast furnace, and serpentine, miscellaneous raw material powder such as dust, scale, and return ore, and solid fuel such as powdered coke. Then, it is mixed-granulated, and the granulated sintering raw material thus obtained is charged into a Dwight-Lloyd type sintering machine and fired. Here, the sintered compounded raw materials usually aggregate with each other to form pseudo-particles because they contain water during granulation. This granulated sinter raw material for producing pseudo-partitioned sinter is useful for ensuring good aeration of the sinter raw material charging layer when loaded on the pallet of the sinter machine, and is sintered. It will be an effective existence for the smooth progress of the reaction.

It is considered that the granulated sintered raw material that has been made into pseudo-particles has a granulated shape, especially a larger shape, and better ventilation can be obtained. Therefore, various methods for improving the granulation property are studied. It has been. For example, Patent Document 1-5 relating to a method for adjusting the amount of fine powder adhering to coarse particles as nuclei particles (pretreatment method for sintering raw material) in order to improve the granulation property of iron ore powder. There is such a suggestion.

However, the techniques for producing granulated and sintered raw materials disclosed in these documents have the problem of high cost, and the appropriate particle size of the ore when mixing fine-grained iron ore into the granulated and sintered raw material. The value has not been considered.

In addition, there is also a proposal of a technique for crushing a high water of crystallization ore and then mixing it with other raw materials to granulate it into a granulated sintering raw material. (Patent Documents 6 and 7)

However, the fact is that the use of high water of crystallization ore is not preferable from the viewpoint of calorific value and packed bed.

In addition, there is a proposal of a technique (Patent Document 8) in which high porosity iron ore is crushed, mixed with other raw materials, and then granulated. It also has the characteristics of low Fe and high water of crystallization, and it is known that even if it is crushed, it adversely affects the operation of the sintering machine in terms of components.

Another method is a _{pretreatment method in which fine iron ore having a SiO 2} content of 3 to 6 mass% and particles larger than 63 μm having a mass of 90 mass% or more with respect to the total mass of fine iron ore is crushed and used (a pretreatment method). There is also a proposal of Patent Document 9). However, regarding this technique, proper compounding when using fine granules has not been studied, and the method of using the fine granule raw material in sintering is unknown.

Japanese Unexamined Patent Publication No. 2005-350770 Japanese Unexamined Patent Publication No. 2007-77512 Japanese Unexamined Patent Publication No. 2008-240159 Japanese Unexamined Patent Publication No. 2010-242226 Japanese Unexamined Patent Publication No. 2013-32568 Japanese Unexamined Patent Publication No. 2014-196548 Japanese Unexamined Patent Publication No. 2008-261016 Japanese Unexamined Patent Publication No. 2007-138244 Japanese Unexamined Patent Publication No. 2016-17211

The present invention overcomes the above-mentioned problems of the prior art, and in particular, even when a large amount of fine iron ore having a relative size of −500 μm is blended, the nuclear powder index described in detail later. A method for producing a granulated sintered raw material, which is effective in improving the productivity of the sintered ore as well as improving the granulation property, and sintering using this raw material. The purpose is to propose a method for producing ore.

The present invention solves the above-mentioned problems to be solved by producing a granulated sinter raw material using a sinter compounding raw material containing powdery and granular iron ore, and further using the granulated sinter raw material to sinter ore. It proposes a method of manufacturing. That is, first, in the production of the granulated sintered raw material, attention is paid to the nuclear powder index described in detail later, a sintered compound raw material having a nuclear powder index of 2.0 or more is used, and the baking according to the present invention is used. The production of ore is characterized by sintering using the granulation sintering raw material obtained as described above.

That is, in the present invention, first, when a sintered compound raw material containing powdered and granular iron ore is granulated to be a granulated sintered raw material, the sintered compound raw material has a particle ratio of −500 μm of 30 mass%. Nuclear powder index that is exceeded and is defined below;
Nuclear powder index = {(+ 1 mm particle ratio) + (-20 μm particle ratio)} / (-500 μm particle ratio)
We propose a method for producing a granulated sintering raw material, which is characterized by having a value of 2.0 or more.

Secondly, the present invention produces a sinter by granulating a sinter compounding raw material containing powdered and granular iron ore and calcining the obtained granulated sinter raw material with a sinter. In the method, the sintered compound raw material has a particle ratio of −500 μm exceeding 30 mass%, and has a nuclear powder index defined below;
Nuclear powder index = {(+ 1 mm particle ratio) + (-20 μm particle ratio)} / (-500 μm particle ratio)
We propose a method for producing a sinter, which is characterized by having a value of 2.0 or more.

In addition, in the present invention, the following configuration;
(1) The granulated sintering raw material must be granulated using quicklime as a binder.
(2) When a granulated sintered raw material is produced using the sintered compound raw material and quick lime, the quick lime is added to the exterior in the latter half of the granulation.
(3) At least a part of the powdered iron ore in the sinter compounding raw material contains particles having a size of -20 μm in an amount of 30 mass% or more.
Is a more preferred embodiment.

According to the present invention, the nuclear powder index indicating the blending ratio of powdered iron ore of +1 mm, -20 μm, and −500 μm should be within a suitable range of 2.0 or more, and calcination should be added as a binder. By adopting the main method, it is possible to obtain high granulation performance even under a large amount of fine iron ore, and finally to contribute to the improvement of sinter productivity. It is possible to establish and propose a desirable granulation sinter raw material and sinter manufacturing technology.

It is a figure which shows the relationship between the particle size and the air volume of the added iron ore with different fine powder ratios. It is a figure which shows the relationship between the maximum adhesive force and the ratio of −63 μm particles. It is a figure which shows the relationship between the maximum adhesive force and the ratio of -20 μm particles. It is a figure which shows the relationship between the ratio of −500 μm, and the granulation particle diameter. It is a figure which shows the relationship between the ratio of −20 μm, and the sintering production rate. It is a figure which shows the relationship between the nuclear powder index and the sintering production rate.

The inventors first investigated the influence of the particle size of the raw material (iron ore) on the granulation property when granulating the "sintered compound raw material" to produce the "granulated sintered raw material". That is, in this investigation, iron ore sieved to each particle size was transferred to the base formulation, and a granulation test and an aeration test were performed. As the raw material for the experiment, the raw materials (iron ores A to D) shown in Table 1 below were used (CW = water of crystallization). The iron ore B is obtained by crushing the iron ore A and sieving it to -1 mm (less than 1 mm), and adding a certain amount to control the air permeability. In this test, in particular, iron ore D, which is a crude concentrate, was crushed and iron ore sieved by a (63 to 125/125 to 250/250 to 500/500 to 1000) μm sieve was added. Then, as shown in Table 2 below, in order to investigate the influence of the particle size of the coarse concentrate, the above test was also conducted on the one containing no iron ore D (formulation 6) as a condition for the base formulation.

In each of the above tests, each sintered compound raw material 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 cylindrical container of 150 mmφ and 380 mmH. The air volume was measured at a negative pressure of 700 mmaq, indicating air permeability. In this test, the water content of the granulated product was changed in the range of 6 to 10 mass%, and the water content at the time of the best ventilation was used for each formulation, and the formulations 1 to 5 were 8 mass at all added particle sizes. % Was optimal, and in formulation 6, 9 mass% was optimal. In addition, the proper granulation water content increased in the compound 6 because of the large amount of ore C having a large amount of water of crystallization. An ore with a large amount of water of crystallization generally has many pores, and water permeates into the ore during granulation, so that more water is required than a dense ore. Further, regarding the formulations 1 to 5, although the particle size was different, the proper water content did not change because the ore type did not change.

As a result, in the air permeability test, as shown in FIG. 1, the air permeability of -63 μm (less than 63 μm) was better than that of the base formulation 6. However, it was found that a particle size of +63 μm causes deterioration of air permeability. Therefore, it was found that the addition of +63 μm particles adversely affects the granulation property and the air permeability. From this, it is considered that increasing the composition of the particles of −63 μm leads to the improvement of the air permeability. Summarizing the above, it can be said that when blending -1 mm (-1000 μm) particles, increasing the blending of -63 μm particles, that is, fine iron ore, is effective in improving air permeability.

By the way, the granulation phenomenon of powdered iron ore is a phenomenon in which fine iron ore is sequentially attached to the surface of nuclear particles. Therefore, the adhesion of fine iron ore to the surface of nuclear particles is important during granulation. Therefore, a shear test was conducted to measure the adhesive force that affects granulation. In this test, -500 μm powdered iron ore sieved with a 500 μm sieve was placed in a container (43 mmφ) containing a fixed mold and a movable mold, compressed at 200 kgf by an upper piston, and then compressed at 200 kgf. This was done by measuring the shear stress according to the normal stress by pulling the movable part in the horizontal direction with a pull gauge while reducing the normal stress. Here, as the adhesive force, the shear stress when the normal stress became 0 kgf was used. The test was performed on iron ore A and iron ores C to F in Table 3. The particle size of the sample was evaluated for each iron ore, one sieved to −500 μm and a sample prepared to 63 to 125 μm, and further evaluated the sample obtained by crushing iron ore D.

As a result, as shown in Table 3, FIG. 2 and FIG. 3 below, it was found that the adhesive force of iron ore increased as the ratio of −63 μm or −20 μm increased. Here, the ratios of −63 μm and −20 μm are the results of sieving to −500 μm, aligning to 63 to 125 μm, and measuring the particle size of the crushed iron ore D by the laser scattering / dispersion measurement method. In particular, when multiple regression analysis was performed using a quadratic function for the ratios of -63 μm and -20 μm and the adhesive force, it was 0.93 when the correlation coefficient was -63 μm, and 0.98 at -20 μm. It was found that the proportion of particles of -20 μm contributed more to the adhesive force.

In addition, from the test results with the same particle size of iron ore, it was found that even if the brand of iron ore changes, the adhesive strength does not increase without -20 μm. In this respect, in the conventional invention (Japanese Patent Laid-Open No. 2008-261016), it was considered that goethite or kaolinite is selectively crushed when crushed, so that the contribution rate to the adhesive force is high. In the present invention, it has been found that by making the particle size of iron ore finer, the adhesive force is greatly increased even in iron ore D having goethite and kaolinite of 0.1% or less (measured by XRD).

Next, a granulation test and a sintering test were carried out in which the ratio of −20 μm was changed. In this test, iron ore G, which is a fine-grained iron ore but has a small amount of -20 μm, and iron ore H, which has been crushed, were tested. The test conditions and results are shown in Table 4 below. Regarding iron ore A, the core / powder ratio is different between Case 1 and Case 2. Further, in this formulation, the test was conducted so that the basicity was 2.1 and the SiO _{2 was also constant.} In carrying out the test, the sample was granulated with a drum mixer for 6 minutes and calcined using a pan tester. When the sintered sinter cake is dropped once from a height of 2 m, the product has a particle size of +10 mm, and the weight is divided by (sinter cake weight-bedding ore weight) to obtain the yield. And said. The sintering production rate (t / (h · m ² )) was taken as a value obtained by dividing the weight of the product by the firing time and the cross-sectional area of the test pot.

As shown in FIG. 4, in case 1 where the amount of -20 μm is large, the granulated particle size increases even if the amount of fine powder (-500 μm), which is usually considered difficult to granulate, increases, while the case 2 where the amount of -20 μm is small. Then, it was found that the granulated particle size became smaller due to the increase in the fine powder. However, in Case 1 where the granulated particle diameter becomes large, it is clear that the production rate in sintering decreases as shown in FIG. 5, even though the granulated particles increase by -20 μm and the granulated particles become large. became.

In general, pseudo-particles, which are granulated and sintered raw materials obtained by granulating iron ore (raw material) in which nuclear particles and fine particles are mixed, have fine particles and particles slightly smaller than the nuclear particles attached around the nuclear particles. It usually has a (covered) structure. In the wet zone of the sintering machine, such pseudo-particles have a reduced strength because the coating layer portion absorbs moisture, which reduces voids in the packed bed (sintered raw material charging layer). May interfere with ventilation. In order to solve this problem, it is important to maintain the strength of the granulated particles (granulation and sintering raw material) in the wet zone.

As a method of maintaining the strength of the granulated sintered raw material in the wet zone, it is better to prevent the aggregate (+1 mm nuclei particles) that does not collapse even in the wet zone from decreasing with respect to the amount of fine powder, or rather to increase it. It is effective, and this makes it possible to improve the air permeability. That is, the +1 mm (1 mm or more) particles become nuclear particles during granulation and promote the granulation action, and since the particles themselves are large, they play an action of improving the air permeability during sintering. Further, in the layer in which the sintered raw material is charged, the aeration resistance increases in the wet zone where the water content increases and the strength of the granulated particles decreases and in the molten zone where the raw material melts, but +1 mm aggregate particles are present. By doing so, it works to suppress the decrease in air permeability.

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

In this regard, the inventors adversely affect the air permeability by adding the ratio of +1 mm particles that become nuclei during granulation and aggregate during sintering and the ratio of -20 μm particles that contribute to granulation. It was found that it can be arranged by the following nuclear powder index, which is the value divided by the particle ratio of −500 μm.
That is, the nuclear powder index can be expressed by the following formula (1).
[Equation 1]
Nuclear powder index = {(+ 1 mm particle ratio) + (-20 μm particle ratio)} / (-500 μm particle ratio)

FIG. 6 shows the relationship between the nuclear powder index and the sintering production rate. As can be seen from this figure and as will be clear from the examples described later, the sum of the particle ratios of (+1 mm and -20 μm) with respect to the −500 μm particles that adversely affect the sinterability of the granulated particles. ), That is, by setting the nuclear powder index to 2.0 or more, it is possible to produce a granulated sintered raw material for maintaining preferable sinterability even when the ratio of -500 μm particles is high. I found it.

Further, in the present invention, in order to suppress the influence of the sintering raw material charging layer on the sintering machine in the wet zone, a method of externally adding quicklime as a binder in the latter half of the granulation treatment process by the drum mixer is adopted. .. In the granulation treatment process, adding quicklime as a binder to the exterior has two effects. One of them is the action of absorbing water in the wet zone, leaving unreacted CaO with water, and is effective in suppressing the formation of slurry of pseudo particles. The other point is that Ca (OH) _{2 that} has reacted with water is on the outer surface side of the pseudo particles, which reacts with _{CO 2 in the exhaust gas to generate fine CaCO 3} and therefore the pseudo particles. A strong layer is formed on the surface, and it is possible to form a packed layer (sintered raw material charging layer) that is not easily crushed even in a wet zone.

[Example 1]
In this example, the following sample (basicity: 2.0, SiO ₂ : 5.0 mass%) was granulated with a drum mixer for 6 minutes and sintered using a pan tester. When the sintered sinter cake is dropped once from a height of 2 m, a product having a particle size of +10 mm is regarded as a product, and the value obtained by dividing the weight by (sinter cake weight-bedding ore weight) is defined as the yield. did. The sintering production rate (t / (h · m ² )) was taken as a 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, as shown in Table 5 and FIG. 6, Case 1-1, in which the sum of the particle ratios of +1 mm and -20 μm was increased 2.0 to 2.3 times with respect to the adversely affecting −500 μm particles. In Cases 3-1 and 3-3, even if fine iron ore containing a high proportion of -500 μm particles is contained, the other cases 1-2, 1-3, 3-2, 3-4 It was confirmed that a stable and high sintering production rate could be maintained.

[Example 2]
In this example, the result of examining the presence or absence of quicklime addition and the timing of addition will be described. As shown in Table 6 below, the nuclear powder index was set to 2.3, 2.2, and 2.2, respectively, and the production was performed for the example without quicklime and the example with quicklime (interior) and with quicklime (exterior). The effect on the rate was investigated. Other conditions are as follows.
In this example, a sample (basicity: 2.1, SiO ₂ : 4.7 mass%) is granulated with a drum mixer for 5 minutes, fired using a pan tester, and after sintering. When a sinter cake is dropped once from a height of 2 m, a product having a particle size of +10 mm is used as a product, and the value obtained by dividing the weight by (sinter cake weight-bedding ore weight) is used as the yield, and sintering production is performed. The ratio (t / (h · m ² )) was the value obtained by dividing the product weight by the firing time and the cross-sectional area of the test pot.

When the results were investigated for the effect of the presence or absence of quicklime on the production rate, the one with quicklime added showed better results.

It is considered that this is because the binder effect of quicklime increases the strength of the pseudo-particles in the cold, and CO2 at the time of sintering further supports the packed bed in the wet zone.

In this test, the effect of exteriorizing quicklime was also verified. That is, the following sample (basicity and SiO ₂ : constant) was granulated with a drum mixer for 5 minutes and sintered using a pan tester. In the case of exteriorizing quicklime, the exterior was added with quicklime at the stage of 1/10 of the granulation time of the drum mixer, and then firing was performed. When the sintered sinter cake is dropped once from a height of 2 m, the product has a particle size of +10 mm, and the value obtained by dividing the weight by (sinter cake weight-bedding ore weight) is used as the yield. The sintering production rate (t / (h · m ² )) was taken as a 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 better than that of the interior by exterior. That is, it was found that when fine powder was added, the production rate was further improved by exteriorizing quicklime. In the case of the addition of quicklime, it was confirmed that the production rate was higher than that of [Example 1] due to the effect of the addition of quicklime.

Claims (5)

When a sintered compounded raw material containing powdered and granular iron ore is granulated into a granulated sintered raw material, the sintered compounded raw material has a particle ratio of −500 μm exceeding 30 mass% and a particle ratio of +1 mm of 58 mass. % Or less, and the nuclear powder index defined below is 2.0 or more, which is a method for producing a granulated sintered raw material.
Nuclear powder index = {(+ 1 mm particle ratio) + (-20 μm particle ratio)} / (-500 μm particle ratio) The method for producing a granulated sintered raw material according to claim 1, wherein the granulated sintered raw material is granulated using quicklime as a binder. The granulated sintered raw material according to claim 1 or 2, wherein when the granulated sintered raw material is produced using the sintered blended raw material and the fresh lime, the fresh lime is added to the exterior in the latter half of the granulation. Manufacturing method. The structure according to any one of claims 1 to 3, wherein at least a part of the powdered iron ore in the sinter-blended raw material contains particles having a size of −20 μm in an amount of 30 mass% or more. Manufacturing method of grain sintering raw material. In a method for producing a sinter by granulating a sinter compounding raw material containing powdered and granular iron ore and firing the obtained granulated sinter raw material with a sinter machine, the sinter compounding raw material is used. Manufacture of sinter, characterized in that the particle ratio of −500 μm is more than 30 mass%, the particle ratio of +1 mm is 58 mass% or less, and the nuclear powder index defined below is 2.0 or more. Method.
Nuclear powder index = {(+ 1 mm particle ratio) + (-20 μm particle ratio)} / (-500 μm particle ratio)

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