JP5224917B6 - Manufacturing method of sintered raw material - Google Patents

Description

The present invention relates to a method for producing a sintered raw material.

In recent years, the supply of iron ore such as hematite, which has been conventionally used as the main stream in sintering machines, has decreased, and the supply of iron ore with a high crystal water content (3 mass% or more) has increased. This iron ore with a high crystallization water content has more fine powder than conventionally used iron ore, so if this iron ore is charged into a sintering machine without pre-treatment, the permeability of the sintering machine will be affected. This prevents the production of high-quality sintered ore with good productivity. For this reason, it is necessary to granulate the iron ore before charging it into the sintering machine, but it has the drawbacks of poor wettability with water and low granulation properties compared to conventionally used iron ore. Therefore, a technology to granulate it has become necessary.
For example, Patent Document 1 discloses a technique of pulverizing iron ore and limestone so that 80% by weight or more is 250 μm or less and producing granules in the presence of water. Further, Patent Document 2 discloses a technique for producing a granulated product of fine ore through two granulation processes.

Japanese Patent Application Publication No. 4-80327 Japanese Unexamined Patent Publication No. 53-123303

However, in the conventional pre-treatment method for sintering raw materials, there are still the following problems that need to be solved.
The method disclosed in Patent Document 1 requires the effort of pulverizing all the limestone that plays a role as a binder, and the pulverization increases manufacturing costs, making it uneconomical and resulting in very poor productivity of the granulated product. . In addition, if only 80% by weight or more is made up of pulverized particles with a diameter of 250 μm or less, the strength of the granules manufactured using the same, that is, the P-type granules, cannot be increased to the desired strength. When conveying granules via multiple belt conveyors, there is a risk that the granules may become powder during transfer.
Further, the method disclosed in Patent Document 2 has the possibility of improving the strength of the granulated product. However, for example, when manufacturing a granulated product in which fine powder is attached to coarse particles serving as core particles, that is, an S-type granulated product, the thickness of the deposited fine powder cannot be controlled. For this reason, if the adhesion thickness is thick, coke will be buried inside the granules, making it difficult to produce sintered ore with the desired quality, leading to a decrease in the yield of sintered ore, and productivity is lost.

The present invention was made in view of the above circumstances, and is capable of handling iron ore raw materials containing a larger amount of fine powder than before, and produces granules with improved granulation properties and strength than before. The purpose of the present invention is to provide a method for producing a sintered raw material that can produce sintered ore with high quality.

The method for producing a sintered raw material according to claim 1, which meets the above object, comprises two or more types of raw materials each including coarse particles with a sieve size of 1 mm or less and fine particles with a sieve size of 1 mm or less, and a crystal water content of some or all of them is 3 mass. % or more of iron ore to produce a sintering raw material, the method comprises:
The first granulator produces a sintered raw material consisting of granules S by attaching the fine powder and coke powder to the coarse particles that will become core particles, and the second granulator produces the fine powder. A sintering raw material consisting of granules P, which are pellets to be used, is manufactured.

Here, when manufacturing granules S (hereinafter also referred to as S-type granules) in which fine powder is attached to coarse particles that become core particles, the core particles (coarse iron ore or coarse coke) are When the thickness of fine powder adhesion increases, it becomes difficult for the granules to burn to the inside, and the productivity of the sintered ore in the sintering machine deteriorates. In addition, when producing granules P that are granulated with only fine powder or mainly with fine powder (hereinafter also referred to as P-type granules), it is necessary to It is necessary to crush everything down to the particle size, which places a heavy load on the crushing equipment and is not practical.

In the method for producing a sintering raw material according to claim 1, iron ores (also referred to as iron ore types) each containing coarse particles and fine powders include, for example, mara mamba ore (locality brand: West Angelus), pisolite ore (locality brand). : Yandy, Loeb River), high phosphorous Brockman ore, etc. can be used. In general, if the brand of origin differs, the component composition and particle size structure will change, so in this application, cases where the brand of origin differs are treated as different iron ore types.
Further, as the first and second granulating devices, for example, a drum mixer, an Eirich mixer, a disk pelletizer, a Prussia mixer, etc. can be used.

As the iron ore having a crystal water content of 3 mass% or more, for example, Maramamba ore (local brand: West Angelus), pisolite ore (local brand: Yandy, Robe River), high phosphorus Brockmann ore, etc. can be used. In general, different brands of origin will have different compositions of ingredients and particle size, so if the brands of origin are different, it is best to treat them as different types of iron ore.
Furthermore, the ratio of using iron ore with crystal water content of 3 mass% or more is 40 mass% or more of the new iron ore raw material (excluding return ore used as raw material after passing through the sintering machine). It is preferable that the iron ore has a crystal water content of 3 mass% or more. This is because when the amount exceeds 40 mass%, the increase in fine powder becomes significant and the effect of the invention becomes significant. This is because when the amount is less than 40 mass%, although the invention has an effect, it is not significant.

The method for producing a sintered raw material according to claim 1 uses the remaining fine powder that is not supplied to the first granulation device as a raw material for the second granulation device, so that the granulation property and strength are improved compared to the conventional method. Granules can be easily produced.
In this way, it is possible to provide a method for producing a sintering raw material that can be used with iron ore raw materials containing a larger amount of fine powder than conventional methods.

Next, embodiments embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention.
Here, FIG. 1 is an explanatory diagram of a method for producing a sintered raw material according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the influence of the fine powder adhesion thickness of S-type granules on the coke combustion index. FIG. 3 is an explanatory diagram showing the crushing strength required to suppress the collapse of the P-type granules, and FIG. 4 is an explanatory diagram showing the influence of the manufacturing conditions of the P-type granules on the crushing strength.

As shown in FIG. 1, the method for producing a sintering raw material according to an embodiment of the present invention uses three types of iron ores, each containing coarse particles and fine particles, namely pisolite ore, mara mamba ore, and high phosphorus blockman ore. S-type granules (granules S), which are made from ore and have fine powder attached to coarse particles that serve as core particles, and P-type granules (granules P), which are granulated mainly from fine powders. This is a method of manufacturing. In addition, the raw materials further include iron ore consisting essentially only of fine powder, that is, kneading dust generated in the steel mill, pellet feed (ore type: MBR-PF), and other iron ores. This will be explained in detail below.

Maramamba ore, pisolite ore, and high-phosphorus Brockmann ore are all also called limonite (Fe ₂ O ₃ .nH ₂ O), and are iron ores with crystal water content of 3 mass% or more, for example, about 10 mm ( In this embodiment, the particles range from coarse particles (about 8 mm) to fine particles of 250 μm or less.
This pisolite ore, coke breeze, other iron ores, and limestone are used to produce S-type granules, and Maramamba ore, high-phosphorus Brockmann ore, kneaded dust, and pellet feed are used to produce P-type granules. Manufacture things.

First, a method for manufacturing S-type granules will be explained.
As shown in FIG. 1, pisolite ore containing coarse particles and fine powder is sieved by a sieve sorter 10. In addition, in this embodiment, a sieve mesh of 3 mm is used as the sieve size of the sieve sorter 10, but the sieve size is not limited to this.
Since the iron ore on the sieve is coarse grained, it is used as core particles without treatment. On the other hand, the iron ore under the sieve is charged into the Eirich mixer 11, and is kneaded and granulated with a binder such as limestone.

The above-mentioned kneaded granules are charged into an S-type drum mixer (an example of a first granulation device) 12 together with coke powder, other iron ore, and limestone, and the coke powder and other powder are placed around the core particles. Fine powder (for example, 250 μm or less) contained in iron ore and limestone is deposited. As a result, S-type granules are produced in which the average thickness of the fine powder adhering to the periphery of the core particles is 50 to 300 μm. In addition, during the production of S-type granules, some of the particles with particle diameters exceeding 250 μm contained in coke breeze, other iron ore, and limestone are passed through the S-type drum mixer together with the S-type granules. It is discharged from within 12.

Here, the reason why the average thickness of fine powder adhesion of the S-type granules is defined in the range of 50 to 300 μm will be explained with reference to FIG. 2.
The average thickness of fine powder adhesion, which is the horizontal axis in FIG. 2, was calculated using the manufactured S-type granules according to the following procedure.
(1) First, the target raw material is completely separated into particles such as fine powder and coarse particles by washing with water, etc., and the bottom of the sieve is sieved in the order of sieving with sieve meshes of 5 mm, 2 mm, 1 mm, 0.5 mm, and 0.25 mm. Then, the weight ratio of each particle size section was determined (weight g of each particle size section when the whole particle size section is 100 g).

(2) Determine the representative particle diameters (7.5 mm, 3.5 mm, and 1.5 mm, respectively) for each section of 5 mm or more, less than 5 mm and 2 mm or more, and less than 2 mm and 1 mm or more, which will be core particles, and make the entire particle 100 g. The number of core particles for each representative particle size was calculated from the weight ratio of each particle size range in each case. At that time, the core particle density was set to 4 g/cm ³ .
(3) When distributing the fine powder of 0.25 mm or less, which is the powder adhering to the core particles, to each of the above-mentioned core particle sections, each core particle section is The weight of fine powder to be distributed was determined.
(4) The adhesion thickness of each core particle was calculated from the number of particles of each zone representative particle diameter of the core particles calculated in (2) and the weight of the fine powder to be distributed calculated and determined in (3). At that time, the bulk density of the adhered powder layer was set to 2 g/cm ³ .
(5) The adhering powder thickness of each core particle section was weighted and averaged by the weight ratio of each particle size section to obtain the fine powder adhering average thickness.

The coke combustion index, which is the vertical axis in Figure 2, corresponds to the yield of sintered ore obtained by sintering S-type granules, and as the coke combustion index increases, the yield of sintered ore increases. This shows that the yield is also improved.
FIG. 2 shows the relationship between the fine powder adhesion thickness (μm) and the coke combustion index in a test in which raw materials with various particle size distributions were granulated and then sintered in a pot test.
As shown in FIG. 2, the coke combustion index tended to increase as the thickness increased until the fine powder adhesion thickness reached 100 μm, and then decreased as the thickness increased.
Considering the above-mentioned factors to not affect the deterioration of the yield of sintered ore, the average thickness of fine powder adhesion is specified to be 50 to 300 μm, preferably the upper limit is 250 μm, and more preferably 220 μm. .

Based on the above knowledge, three types of S are currently used in operation: one with an average thickness of fine powder adhesion of 204 μm (currently), one with a thinner adhesion thickness of 88 μm, and one with a thicker adhesion thickness of 327 μm. Type granules were prepared, and each of the S-type granules was charged into a sintering machine, and the influence on the yield of sintered ore was investigated.
In addition, each S-type granule is manufactured with a constant amount of iron ore as a raw material, so the 327 μm S-type granule (pulverized only) is made by crushing the iron ore to make up the insufficient amount of fine powder. The 88 μm S-type granules are produced by attaching them around the core particles and charged into the sintering machine. It is charged into a sintering machine together with mold granules (pelletized). Here, the investigation results of 88 μm S-type granules are not the results of only S-type granules, but the amount of P-type granules blended is small (for example, S-type granules and P-type granules). (approximately 20 to 30 mass% of the total amount of granules), and since coke powder, which serves as a heat source, is not included in the P-type granules, the obtained results can roughly correspond to those of the S-type granules. Conceivable.
As a result of the investigation based on the above premise, a sintered ore yield in line with the coke combustion index shown in the pan test results shown in Figure 2 was obtained.

Next, a method for producing P-type granules will be explained.
As shown in FIG. 1, Maramamba ore and high-phosphorus Brockman ore, each containing coarse particles and fine particles, are sieved by a sieve sorter 13. Note that the sieve size of the sieve sorter 13 is set in the range of 0.5 to 10 mm (3 mm in this embodiment). The iron ore under the sieve that has been sieved by the sieve sorter 13 is pulverized by the pulverizer 15 and charged into the mixer 17 together with kneading dust and pellet feed (MBR-PF), where they are mixed. Note that the sieve sorter 13 and the crusher 15 each constitute a pre-processing device.
At this time, subsequent processing is performed according to the particle size distribution of the crushed iron ore used to produce the P-type granules.

When subsieved iron ore, which is the raw material for P-type granules, is crushed and sized so that 500 μm under is 90 mass% or more and 22 μm under is over 80 mass%, P-type drum mixer (second granulation (Example of apparatus) 18, and after being granulated using water (for example, 5 to 15 mass% in terms of external content), it is sieved by a sieve sorter 19. In addition, if subsieved iron ore, which is the raw material for P-type granules, is crushed and sized so that 500 μm under is 80 mass% or more and 22 μm under is more than 70 mass% and 80 mass% or less, P-type granules After being charged into a mixer 18 and granulated using water (for example, 5 to 15 mass% in terms of external content), it is sieved by a sieve sorter 19 and further dried by a dryer 20.
When subsieved iron ore, which is a raw material for P-type granules, is crushed and sized so that 500 μm under is 40 mass% or more and 22 μm under is 5 mass% or more and 70 mass% or less, P-type drum mixer 18, for example, an organic binder such as pulp waste liquid or cornstarch (for example, it is preferably 0.01 to 3 mass% in external content, and more preferably 0.1 to 3 mass%); and After being granulated using water (for example, 5 to 15 mass% in terms of external content), it is sieved in a sieve sorter 19 and further dried in a dryer 20.
Note that the drying is performed in an atmosphere set at 40° C. or higher and 250° C. or lower, for example, for about 20 to 60 minutes. In addition, when measuring the mass% of fine powder particles such as under 500 μm and under 22 μm, a laser diffraction scattering measuring instrument (MICROTRAC FRA type manufactured by Nikkiso Co., Ltd., measurement range: 0.1 to 700 μm) was used.

Here, the reason why the subsequent processing was changed depending on the particle size distribution of the crushed and sized iron ore will be explained.
When fine powder is used as a raw material for P-type granules (hereinafter also referred to as pellets), the strength (crushing strength) of the P-type granules is low, so it is necessary to increase this strength to an appropriate value. Therefore, if we define this necessary strength by taking into account the fact that the belt conveyor (not shown) has enough strength to be transferred five times or more (corresponding to the transfer of an actual machine), the diameter will be as shown in Figure 3. It can be seen that a strength of 2 kgf (2 kgf/10 mmφ/1 piece) or more is required per 10 mm P-type granule.
Therefore, a processing method that satisfies this requirement of 2 kgf/10 mmφ/1 piece or more will be explained with reference to FIG. 4. The raw materials used were Maramamba ore crushed to a size of 3 mm or less, pellet feed, and kneading dust.

As shown in Figure 4, (1) only pulverization, (2) pulverization and drying, and (3) pulverization, drying, and binder addition for the same average particle size, (1) → (2) →(3), the crushing strength of the pellets tended to increase. In addition, the amount of water used for granulation was 10 mass% externally, the amount of binder (pulp waste liquid) added was 1 mass% externally, and drying was performed at 250 ° C. for 30 minutes to remove the moisture contained in the granules. The moisture content was reduced to 5 mass% externally. Here, when iron ore is subjected to only pulverization treatment, if the average particle size is 20 μm or less (90 mass% or more under 500 μm, and over 80 mass% under 22 μm), the produced pellet is 2 kgf/10 mmφ/1 piece. The above conditions can be satisfied.

In addition, when this granulated product is further subjected to drying treatment, even if the average particle size is increased to 100 μm or less (500 μm under is 80 mass% or more, and 22 μm under is more than 70 mass% and 80 mass% or less), the produced pellets are 2kgf/10mmφ・1 or more conditions can be satisfied.
Furthermore, when drying the granules to which a binder has been added, the average particle size can be further increased to 700 μm or less (40 mass% or more of 500 μm or more, and 5 mass% or more and 70 mass% or less of 22 μm or less). The condition of 2kgf/10mmφ/1 or more pellets can be satisfied.
Based on the above, the above-described treatments were performed depending on the pulverized particle size.

The sieve mesh of the sieve sorter 19 that screens the granules granulated by the P-type drum mixer 18 is adjusted so that the granules with a particle size in the range of 1 to 10 mm can be sieved. There is. Note that granules with a particle size of less than 1 mm are charged into the mixer 17 again without being processed, and granules with a particle size of more than 10 mm are crushed in a crusher (not shown) and recycled again. It is charged into a mixer 17 and the particle size is adjusted.
As a result, the granules whose particle size has been adjusted to a range of 1 to 10 mm are subjected to drying treatment as necessary, as described above, to become P-type granules.

In addition, during the production of P-type granules, the iron ore on the sieve is generated by sieving Maramamba ore and high-phosphorus Brockmann ore through a sieve mesh set in the range of 0.5 mm to 10 mm of the sieve sorter 13. is not suitable as a raw material for P-type granules. This is because, as mentioned above, it is difficult to ensure the strength of the P-type granules produced without pulverization, and the crushing load is relatively large compared to subsieve iron ore, making it difficult to operate. This is because of the load involved. Therefore, the iron ore on the sieve is mainly used as the core particles of the S-type granules without being subjected to pulverization treatment.
In this way, the fine powder contained in the Maramamba ore and the high-phosphorus Brockman ore is adjusted in the amount of fine powder mixed by the sieve of the sieve sorter 13, that is, it is not supplied to the S-type drum mixer 12, and the S-type The remainder that is not supplied to the P-type drum mixer 12 as much as possible, that is, almost all of the fine powder, is used as a raw material for the P-type drum mixer 18.

Here, the size of the sieve mesh of the sieve sorter 13 is changed according to the average thickness of fine powder adhering to the S-type granules, and the size of the sieve mesh is changed depending on the average thickness of the fine powder adhering to the S-type granules. By adjusting the amount of coarse particles added to the S-type drum mixer 12, the average thickness of fine powder adhesion can be adjusted to a desired range of 50 to 300 μm.
For example, if the average thickness of fine powder adhesion of S-type granules increases due to a change in the particle size distribution of the iron ore used, use a sieve mesh close to 1 mm in the range of 1 mm or more and feed it to the S-type drum mixer 12. By increasing the amount of core particles in the S-type granules, it is possible to optimize the average thickness of fine powder adhesion. On the other hand, for example, if the average thickness of fine powder adhesion of the S-type granules decreases due to a change in the particle size distribution of the iron ore used, the S-type granules supplied to the S-type drum mixer 12 may be By reducing the amount of core particles in the mold granules, the average thickness of fine powder adhesion can be optimized.

In addition, the size of the sieve mesh of the sieve sorter 13 is changed depending on the manufacturing capacity of either or both of the P-type drum mixer 18 and the pre-processing device, and the amount of iron ore supplied to each device is adjusted. Can be controlled (changed).
For example, if there is margin in the production capacity of each device for producing P-type granules due to changes in the particle size distribution of the iron ore used, use a sieve with a sieve size close to 10 mm to obtain raw materials for producing P-type granules. supply can be increased. On the other hand, for example, if the production capacity of each device for producing P-type granules is insufficient due to changes in the particle size distribution of the iron ore used, use a sieve with a mesh size close to 0.5 mm to produce P-type granules. The amount of raw material supplied for production can be reduced. At this time, measures such as temporarily stocking (storing) the iron ore under the sieve and processing the stocked iron ore if there is sufficient capacity of each device to produce P-type granules are taken. , can also be used as needed.

In addition, when adjusting the sieve size of the sieve sorter 13, intermediate particles that are difficult to become core particles (for example, more than 250 μm and 1 mm or less) contained in the iron ore on the sieve are prevented from adhering to the S-type granules. It is often discharged from the S-type drum mixer 12. In addition, by subjecting the intermediate particles to a pulverization treatment, they can be used as a raw material for P-type granules or as a fine powder to which S-type granules are attached.
The S-type granules and P-type granules produced by the above method are stacked in a sintering machine without mixing, for example, so that 70 to 80 mass% of the total amount is S-type granules. 21 to produce sintered ore.
As a result, it is possible to handle iron ore raw materials containing a larger amount of fine powder than before, and produce granules with improved granulation properties and strength than before, producing sintered ore with good quality. can.

Although the present invention has been described above with reference to one embodiment, the present invention is not limited to the configuration described in the above-described embodiment, and the matters described in the claims It also includes other embodiments and modifications that can be considered within the scope of the above. For example, a case where a method for manufacturing a sintered raw material of the present invention is configured by combining some or all of the embodiments and modifications described above is also included within the scope of the present invention.
In addition, in the embodiment described above, a case has been described in which pisolite ore, mara mamba ore, and high-phosphorus Brockmann ore are used as three types of iron ore containing coarse particles and fine powder, respectively. For example, pisolite ore and mara mamba ore may be used, or other iron ores, such as magnetite (Fe ₃ O ₄ ), hematite (Fe ₂ O ₃ ), may be used. It is also possible to use . Note that it is of course possible to configure the raw material by adding other iron sources, such as iron sources generated within a steelworks, to these iron ores.
In the embodiment, when producing the P-type granules, if the particle size of the fine powder after pulverization and grading is 90 mass% or more under 500 μm and over 80 mass% under 22 μm, a binder is added. Although the powder was granulated without drying and charged into the sintering machine without drying, either or both of the addition of a binder and the drying may be performed as necessary. In addition, when the particle size of the fine powder after pulverization and grading is 80 mass% or more for 500 μm under and more than 70 mass% for 22 μm under and 80 mass% or less, it is granulated without adding a binder, dried and baked. Although the material is charged into a binder, a binder can be added as necessary.

FIG. 2 is an explanatory diagram of a method for producing a sintering raw material according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the influence of the thickness of fine powder adhesion of S-type granules on the coke combustion index. FIG. 2 is an explanatory diagram showing the crushing strength required to suppress the collapse of P-type granules. FIG. 2 is an explanatory diagram showing the influence of manufacturing conditions of P-type granules on crushing strength.

Explanation of symbols

10: Sieve sorter, 11: Eirich mixer, 12: Drum mixer for S type (first granulation device), 13: Sieve sorter, 15: Pulverizer, 17: Mixer, 18: Drum for P type Mixer (second granulation device), 19: Sieve sorter, 20: Dryer, 21: Sintering machine

Claims (1)

A sintering raw material is produced by pre-processing two or more types of iron ore, each containing coarse particles with a sieve size of 1 mm or less and fine particles with a sieve size of 1 mm or less, and in which the crystal water content of some or all of them is 3 mass% or more. A method,
The first granulator produces a sintered raw material consisting of granules S by attaching the fine powder and coke powder to the coarse particles that will become core particles, and the second granulator produces the fine powder. A method for producing a sintering raw material, which comprises producing a sintering raw material consisting of granules P, which are used pellets.

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